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BIOTECHNOLOGY (244 journals)                  1 2 | Last

Showing 1 - 200 of 244 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
Advanced Biomedical Research     Open Access  
Advances in Bioscience and Biotechnology     Open Access   (Followers: 17)
Advances in Genetic Engineering & Biotechnology     Hybrid Journal   (Followers: 9)
Advances in Regenerative Medicine     Open Access   (Followers: 3)
African Journal of Biotechnology     Open Access   (Followers: 6)
Algal Research     Partially Free   (Followers: 11)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Bioinformatics Research     Open Access   (Followers: 7)
American Journal of Polymer Science     Open Access   (Followers: 33)
Amylase     Open Access  
Anadolu University Journal of Science and Technology : C Life Sciences and Biotechnology     Open Access  
Animal Biotechnology     Hybrid Journal   (Followers: 8)
Annales des Sciences Agronomiques     Full-text available via subscription  
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 45)
Applied Biosafety     Hybrid Journal  
Applied Food Biotechnology     Open Access   (Followers: 3)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 67)
Applied Mycology and Biotechnology     Full-text available via subscription   (Followers: 4)
Arthroplasty Today     Open Access   (Followers: 1)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 1)
Asia Pacific Biotech News     Hybrid Journal   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 9)
Asian Pacific Journal of Tropical Biomedicine     Open Access   (Followers: 2)
Australasian Biotechnology     Full-text available via subscription   (Followers: 1)
Banat's Journal of Biotechnology     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 5)
Beitr?ge zur Tabakforschung International/Contributions to Tobacco Research     Open Access   (Followers: 3)
Bio-Algorithms and Med-Systems     Hybrid Journal   (Followers: 2)
Bio-Research     Full-text available via subscription   (Followers: 4)
Bioactive Materials     Open Access   (Followers: 1)
Biocatalysis and Agricultural Biotechnology     Hybrid Journal   (Followers: 4)
Biocybernetics and Biological Engineering     Full-text available via subscription   (Followers: 5)
Bioethics UPdate     Hybrid Journal   (Followers: 1)
Biofuels     Hybrid Journal   (Followers: 11)
Biofuels Engineering     Open Access   (Followers: 1)
Biological & Pharmaceutical Bulletin     Full-text available via subscription   (Followers: 4)
Biological Cybernetics     Hybrid Journal   (Followers: 10)
Biomarkers and Genomic Medicine     Open Access   (Followers: 3)
Biomaterials Research     Open Access   (Followers: 4)
BioMed Research International     Open Access   (Followers: 4)
Biomédica     Open Access  
Biomedical and Biotechnology Research Journal     Open Access  
Biomedical Engineering Research     Open Access   (Followers: 6)
Biomedical Glasses     Open Access  
Biomedical Reports     Full-text available via subscription  
BioMedicine     Open Access  
Biomedika     Open Access  
Bioprinting     Hybrid Journal   (Followers: 1)
Bioresource Technology Reports     Hybrid Journal   (Followers: 1)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 21)
Biosensors Journal     Open Access  
Biosimilars     Open Access   (Followers: 1)
Biosurface and Biotribology     Open Access  
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 1)
BioTechniques : The International Journal of Life Science Methods     Full-text available via subscription   (Followers: 28)
Biotechnologia Acta     Open Access   (Followers: 1)
Biotechnologie, Agronomie, Société et Environnement     Open Access   (Followers: 2)
Biotechnology     Open Access   (Followers: 8)
Biotechnology & Biotechnological Equipment     Open Access   (Followers: 4)
Biotechnology Advances     Hybrid Journal   (Followers: 34)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 159)
Biotechnology and Bioprocess Engineering     Hybrid Journal   (Followers: 6)
Biotechnology and Genetic Engineering Reviews     Hybrid Journal   (Followers: 13)
Biotechnology and Health Sciences     Open Access   (Followers: 1)
Biotechnology and Molecular Biology Reviews     Open Access   (Followers: 2)
Biotechnology Annual Review     Full-text available via subscription   (Followers: 5)
Biotechnology for Biofuels     Open Access   (Followers: 10)
Biotechnology Frontier     Open Access   (Followers: 2)
Biotechnology Journal     Hybrid Journal   (Followers: 17)
Biotechnology Law Report     Hybrid Journal   (Followers: 4)
Biotechnology Letters     Hybrid Journal   (Followers: 34)
Biotechnology Progress     Hybrid Journal   (Followers: 41)
Biotechnology Reports     Open Access  
Biotechnology Research International     Open Access   (Followers: 1)
Biotechnology Techniques     Hybrid Journal   (Followers: 10)
Biotecnología Aplicada     Open Access  
Bioteknologi (Biotechnological Studies)     Open Access  
BIOTIK : Jurnal Ilmiah Biologi Teknologi dan Kependidikan     Open Access  
Biotribology     Hybrid Journal   (Followers: 1)
BMC Biotechnology     Open Access   (Followers: 17)
Cell Biology and Development     Open Access  
Chinese Journal of Agricultural Biotechnology     Full-text available via subscription   (Followers: 4)
Communications in Mathematical Biology and Neuroscience     Open Access  
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computer Methods and Programs in Biomedicine     Hybrid Journal   (Followers: 8)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biotechnology     Hybrid Journal   (Followers: 20)
Crop Breeding and Applied Biotechnology     Open Access   (Followers: 3)
Current Bionanotechnology     Hybrid Journal  
Current Biotechnology     Hybrid Journal   (Followers: 4)
Current Opinion in Biomedical Engineering     Hybrid Journal   (Followers: 1)
Current Opinion in Biotechnology     Hybrid Journal   (Followers: 55)
Current Pharmaceutical Biotechnology     Hybrid Journal   (Followers: 9)
Current Research in Bioinformatics     Open Access   (Followers: 13)
Current Trends in Biotechnology and Chemical Research     Open Access   (Followers: 3)
Current trends in Biotechnology and Pharmacy     Open Access   (Followers: 8)
DNA and RNA Nanotechnology     Open Access  
EBioMedicine     Open Access  
Electronic Journal of Biotechnology     Open Access  
Entomologia Generalis     Full-text available via subscription   (Followers: 1)
Environmental Science : Processes & Impacts     Full-text available via subscription   (Followers: 4)
Experimental Biology and Medicine     Hybrid Journal   (Followers: 3)
Folia Medica Indonesiana     Open Access  
Food Bioscience     Hybrid Journal  
Food Biotechnology     Hybrid Journal   (Followers: 9)
Food Science and Biotechnology     Hybrid Journal   (Followers: 8)
Frontiers in Bioengineering and Biotechnology     Open Access   (Followers: 6)
Frontiers in Systems Biology     Open Access   (Followers: 2)
Fungal Biology and Biotechnology     Open Access   (Followers: 2)
GM Crops and Food: Biotechnology in Agriculture and the Food Chain     Full-text available via subscription   (Followers: 1)
GSTF Journal of BioSciences     Open Access  
HAYATI Journal of Biosciences     Open Access  
Horticultural Biotechnology Research     Open Access  
Horticulture, Environment, and Biotechnology     Hybrid Journal   (Followers: 11)
IEEE Transactions on Molecular, Biological and Multi-Scale Communications     Hybrid Journal   (Followers: 1)
IET Nanobiotechnology     Hybrid Journal   (Followers: 2)
IN VIVO     Full-text available via subscription   (Followers: 4)
Indian Journal of Biotechnology (IJBT)     Open Access   (Followers: 2)
Indonesia Journal of Biomedical Science     Open Access   (Followers: 2)
Indonesian Journal of Biotechnology     Open Access   (Followers: 1)
Indonesian Journal of Medicine     Open Access  
Industrial Biotechnology     Hybrid Journal   (Followers: 18)
International Biomechanics     Open Access  
International Journal of Bioinformatics Research and Applications     Hybrid Journal   (Followers: 14)
International Journal of Biomechatronics and Biomedical Robotics     Hybrid Journal   (Followers: 4)
International Journal of Biomedical Research     Open Access   (Followers: 2)
International Journal of Biotechnology     Hybrid Journal   (Followers: 5)
International Journal of Biotechnology and Molecular Biology Research     Open Access   (Followers: 4)
International Journal of Biotechnology for Wellness Industries     Partially Free   (Followers: 1)
International Journal of Environment, Agriculture and Biotechnology     Open Access   (Followers: 5)
International Journal of Functional Informatics and Personalised Medicine     Hybrid Journal   (Followers: 4)
International Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
International Journal of Nanotechnology and Molecular Computation     Full-text available via subscription   (Followers: 3)
International Journal of Radiation Biology     Hybrid Journal   (Followers: 4)
Iranian Journal of Biotechnology     Open Access  
ISABB Journal of Biotechnology and Bioinformatics     Open Access  
Italian Journal of Food Science     Open Access   (Followers: 1)
JMIR Biomedical Engineering     Open Access  
Journal of Biometrics & Biostatistics     Open Access   (Followers: 3)
Journal of Bioterrorism & Biodefense     Open Access   (Followers: 6)
Journal of Petroleum & Environmental Biotechnology     Open Access   (Followers: 1)
Journal of Advanced Therapies and Medical Innovation Sciences     Open Access  
Journal of Advances in Biotechnology     Open Access   (Followers: 5)
Journal Of Agrobiotechnology     Open Access  
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 7)
Journal of Animal Science and Biotechnology     Open Access   (Followers: 4)
Journal of Applied Biomedicine     Open Access   (Followers: 2)
Journal of Applied Biotechnology     Open Access   (Followers: 2)
Journal of Applied Biotechnology Reports     Open Access   (Followers: 2)
Journal of Applied Mathematics & Bioinformatics     Open Access   (Followers: 5)
Journal of Biologically Active Products from Nature     Hybrid Journal   (Followers: 1)
Journal of Biomaterials and Nanobiotechnology     Open Access   (Followers: 6)
Journal of Biomedical Photonics & Engineering     Open Access  
Journal of Biomedical Practitioners     Open Access  
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Bioprocessing & Biotechniques     Open Access  
Journal of BioScience and Biotechnology     Open Access  
Journal of Biosecurity Biosafety and Biodefense Law     Hybrid Journal   (Followers: 3)
Journal of Biotechnology     Hybrid Journal   (Followers: 63)
Journal of Biotechnology and Strategic Health Research     Open Access   (Followers: 1)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 9)
Journal of Chitin and Chitosan Science     Full-text available via subscription   (Followers: 1)
Journal of Colloid Science and Biotechnology     Full-text available via subscription  
Journal of Commercial Biotechnology     Full-text available via subscription   (Followers: 6)
Journal of Crop Science and Biotechnology     Hybrid Journal   (Followers: 3)
Journal of Ecobiotechnology     Open Access  
Journal of Essential Oil Research     Hybrid Journal   (Followers: 2)
Journal of Experimental Biology     Full-text available via subscription   (Followers: 25)
Journal of Genetic Engineering and Biotechnology     Open Access   (Followers: 5)
Journal of Ginseng Research     Open Access  
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 18)
Journal of Integrative Bioinformatics     Open Access  
Journal of Medical Imaging and Health Informatics     Full-text available via subscription  
Journal of Molecular Biology and Biotechnology     Open Access  
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 13)
Journal of Nano Education     Full-text available via subscription  
Journal of Nanobiotechnology     Open Access   (Followers: 4)
Journal of Nanofluids     Full-text available via subscription   (Followers: 1)
Journal of Organic and Biomolecular Simulations     Open Access  
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)
Journal of Science and Applications : Biomedicine     Open Access  
Journal of the Mechanical Behavior of Biomedical Materials     Hybrid Journal   (Followers: 13)
Journal of Trace Elements in Medicine and Biology     Hybrid Journal   (Followers: 1)
Journal of Tropical Microbiology and Biotechnology     Full-text available via subscription  
Journal of Yeast and Fungal Research     Open Access   (Followers: 1)
Marine Biotechnology     Hybrid Journal   (Followers: 4)
Meat Technology     Open Access  
Messenger     Full-text available via subscription  
Metabolic Engineering Communications     Open Access   (Followers: 4)
Metalloproteinases In Medicine     Open Access  
Microbial Biotechnology     Open Access   (Followers: 10)
MicroMedicine     Open Access   (Followers: 3)
Molecular and Cellular Biomedical Sciences     Open Access   (Followers: 1)
Molecular Biotechnology     Hybrid Journal   (Followers: 13)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Nanobiomedicine     Open Access  
Nanobiotechnology     Hybrid Journal   (Followers: 2)

        1 2 | Last

Journal Cover
Journal of Experimental Biology
Journal Prestige (SJR): 1.611
Citation Impact (citeScore): 3
Number of Followers: 25  
  Full-text available via subscription Subscription journal
ISSN (Print) 0022-0949 - ISSN (Online) 1477-9145
Published by Company of Biologists, The Homepage  [5 journals]
  • Using a shell as a wing: pairing of dissimilar appendages in atlantiid
           heteropod swimming [SHORT COMMUNICATION]
    • Authors: Karakas, F; D'Oliveira, D, Maas, A. E, Murphy, D. W.
      Abstract: Ferhat Karakas, Daniel D'Oliveira, Amy E. Maas, and David W. Murphy

      Atlantiid heteropods are zooplanktonic marine snails which have a calcium carbonate shell and single swimming fin. They actively swim to hunt prey and vertically migrate. Previous accounts of atlantiid heteropod swimming described these animals sculling with the swimming fin while the shell passively hung beneath the body. Here, we show, via high-speed stereophotogrammetric measurements of body, fin and shell kinematics, that the atlantiid heteropod Atlanta selvagensis actively flaps both the swimming fin and shell in a highly coordinated wing-like manner in order to swim in the intermediate Reynolds number regime (Re=10–100). The fin and shell kinematics indicate that atlantiid heteropods use unsteady hydrodynamic mechanisms such as clap-and-fling and delayed stall. Unique features of atlantiid heteropod swimming include the coordinated pairing of dissimilar appendages, use of the clap and fling mechanism twice during each stroke cycle, and the fin's extremely large stroke amplitude, which exceeds 180 deg.
      PubDate: 2018-12-07T01:32:09-08:00
      DOI: 10.1242/jeb.192062
      Issue No: Vol. 221, No. 23 (2018)
  • Side-swimming plankton snail flaps shell like a fin [INSIDE JEB]
    • Authors: Knight K.
      Abstract: Kathryn Knight

      PubDate: 2018-12-07T01:32:09-08:00
      DOI: 10.1242/jeb.194746
      Issue No: Vol. 221, No. 23 (2018)
  • High field metabolic rates of wild harbour porpoises [RESEARCH ARTICLE]
    • Authors: Rojano-Donate, L; McDonald, B. I, Wisniewska, D. M, Johnson, M, Teilmann, J, Wahlberg, M, Hojer-Kristensen, J, Madsen, P. T.
      Abstract: Laia Rojano-Donate, Birgitte I. McDonald, Danuta M. Wisniewska, Mark Johnson, Jonas Teilmann, Magnus Wahlberg, Jakob Hojer-Kristensen, and Peter T. Madsen

      Reliable estimates of field metabolic rates (FMRs) in wild animals are essential for quantifying their ecological roles, as well as for evaluating fitness consequences of anthropogenic disturbances. Yet, standard methods for measuring FMR are difficult to use on free-ranging cetaceans whose FMR may deviate substantially from scaling predictions using terrestrial mammals. Harbour porpoises (Phocoena phocoena) are among the smallest marine mammals, and yet they live in cold, high-latitude waters where their high surface-to-volume ratio suggests high FMRs to stay warm. However, published FMR estimates of harbour porpoises are contradictory, with some studies claiming high FMRs and others concluding that the energetic requirements of porpoises resemble those of similar-sized terrestrial mammals. Here, we address this controversy using data from a combination of captive and wild porpoises to estimate the FMR of wild porpoises. We show that FMRs of harbour porpoises are up to two times greater than for similar-sized terrestrial mammals, supporting the hypothesis that small, carnivorous marine mammals in cold water have elevated FMRs. Despite the potential cost of thermoregulation in colder water, harbour porpoise FMRs are stable over seasonally changing water temperatures. Varying heat loss seems to be managed via cyclical fluctuations in energy intake, which serve to build up a blubber layer that largely offsets the extra costs of thermoregulation during winter. Such high FMRs are consistent with the recently reported high feeding rates of wild porpoises and highlight concerns about the potential impact of human activities on individual fitness and population dynamics.
      PubDate: 2018-12-06T14:50:25-08:00
      DOI: 10.1242/jeb.185827
      Issue No: Vol. 221, No. 23 (2018)
  • Porpoises have higher metabolic rates than thought to keep warm in cold
           water [INSIDE JEB]
    • Authors: Knight K.
      Abstract: Kathryn Knight

      PubDate: 2018-12-06T14:50:25-08:00
      DOI: 10.1242/jeb.194712
      Issue No: Vol. 221, No. 23 (2018)
  • Innate visual preferences and behavioral flexibility in Drosophila
    • Authors: Grabowska, M. J; Steeves, J, Alpay, J, Van De Poll, M, Ertekin, D, van Swinderen, B.
      Abstract: Martyna J. Grabowska, James Steeves, Julius Alpay, Matthew Van De Poll, Deniz Ertekin, and Bruno van Swinderen

      Visual decision making in animals is influenced by innate preferences as well as experience. Interaction between hard-wired responses and changing motivational states determines whether a visual stimulus is attractive, aversive or neutral. It is, however, difficult to separate the relative contribution of nature versus nurture in experimental paradigms, especially for more complex visual parameters such as the shape of objects. We used a closed-loop virtual reality paradigm for walking Drosophila to uncover innate visual preferences for the shape and size of objects, in a recursive choice scenario allowing the flies to reveal their visual preferences over time. We found that Drosophila melanogaster display a robust attraction/repulsion profile for a range of object sizes in this paradigm, and that this visual preference profile remains evident under a variety of conditions and persists into old age. We also demonstrate a level of flexibility in this behavior: innate repulsion to certain objects could be transiently overridden if these were novel, although this effect was only evident in younger flies. Finally, we show that a neuromodulatory circuit in the fly brain, Drosophila neuropeptide F (dNPF), can be recruited to guide visual decision making. Optogenetic activation of dNPF-expressing neurons converted a visually repulsive object into a more attractive object. This suggests that dNPF activity in the Drosophila brain guides ongoing visual choices, to override innate preferences and thereby provide a necessary level of behavioral flexibility in visual decision making.
      PubDate: 2018-12-05T01:02:48-08:00
      DOI: 10.1242/jeb.185918
      Issue No: Vol. 221, No. 23 (2018)
  • An attempt to select non-genetic variation in resistance to starvation and
           reduced chill coma recovery time in Drosophila melanogaster [RESEARCH
    • Authors: Menezes, B. F; Salces-Ortiz, J, Muller, H, Burlet, N, Martinez, S, Fablet, M, Vieira, C.
      Abstract: Bianca F. Menezes, Judit Salces-Ortiz, Heloïse Muller, Nelly Burlet, Sonia Martinez, Marie Fablet, and Cristina Vieira

      Phenotypic variance is attributed to genetic and non-genetic factors, and only the former are presumed to be inherited and thus suitable for the action of selection. Although increasing amounts of data suggest that non-genetic variability may be inherited, we have limited empirical data in animals. Here, we performed an artificial selection experiment using Drosophila melanogaster inbred lines. We quantified the response to selection for a decrease in chill coma recovery time and an increase in starvation resistance. We observed a weak response to selection in the inbred and outbred lines, with variability across lines. At the end of the selection process, differential expression was detected for some genes associated with epigenetics, the piRNA pathway and canalization functions. As the selection process can disturb the canalization process and increase the phenotypic variance of developmental traits, we also investigated possible effects of the selection process on the number of scutellar bristles, fluctuating asymmetry levels and fitness estimates. These results suggest that, contrary to what was shown in plants, selection of non-genetic variability is not straightforward in Drosophila and appears to be strongly genotype dependent.
      PubDate: 2018-12-05T01:02:48-08:00
      DOI: 10.1242/jeb.186254
      Issue No: Vol. 221, No. 23 (2018)
  • Distinct metabolic adjustments arise from acclimation to constant hypoxia
           and intermittent hypoxia in estuarine killifish (Fundulus heteroclitus)
    • Authors: Borowiec, B. G; McClelland, G. B, Rees, B. B, Scott, G. R.
      Abstract: Brittney G. Borowiec, Grant B. McClelland, Bernard B. Rees, and Graham R. Scott

      Many fish experience daily cycles of hypoxia in the wild, but the physiological strategies for coping with intermittent hypoxia are poorly understood. We examined how killifish adjust O2 supply and demand during acute hypoxia, and how these responses are altered after prolonged acclimation to constant or intermittent patterns of hypoxia exposure. We acclimated killifish to normoxia (~20 kPa O2), constant hypoxia (2 kPa) or intermittent cycles of nocturnal hypoxia (12 h:12 h normoxia:hypoxia) for 28 days, and then compared whole-animal O2 consumption rates (MO2) and tissue metabolites during exposure to 12 h of hypoxia followed by reoxygenation in normoxia. Normoxia-acclimated fish experienced a pronounced 27% drop in MO2 during acute hypoxia, and modestly increased MO2 upon reoxygenation. They strongly recruited anaerobic metabolism during acute hypoxia, indicated by lactate accumulation in plasma, muscle, liver, brain, heart and digestive tract, as well as a transient drop in intracellular pH, and they increased hypoxia inducible factor (HIF)-1α protein abundance in muscle. Glycogen, glucose and glucose-6-phosphate levels suggested that glycogen supported brain metabolism in hypoxia, while the muscle used circulating glucose. Acclimation to constant hypoxia caused a stable ~50% decrease in MO2 that persisted after reoxygenation, with minimal recruitment of anaerobic metabolism, suggestive of metabolic depression. By contrast, fish acclimated to intermittent hypoxia maintained sufficient O2 transport to support normoxic MO2, modestly recruited lactate metabolism and increased MO2 dramatically upon reoxygenation. Both groups of hypoxia-acclimated fish had similar glycogen, ATP, intracellular pH and HIF-1α levels as normoxic controls. We conclude that different patterns of hypoxia exposure favour distinct strategies for matching O2 supply and O2 demand.
      PubDate: 2018-12-05T01:02:48-08:00
      DOI: 10.1242/jeb.190900
      Issue No: Vol. 221, No. 23 (2018)
  • Deciphering function of the pulmonary arterial sphincters in loggerhead
           sea turtles (Caretta caretta) [RESEARCH ARTICLE]
    • Authors: Garcia-Parraga, D; Lorenzo, T, Wang, T, Ortiz, J.-L, Ortega, J, Crespo-Picazo, J.-L, Cortijo, J, Fahlman, A.
      Abstract: Daniel Garcia-Parraga, Teresa Lorenzo, Tobias Wang, Jose-Luis Ortiz, Joaquin Ortega, Jose-Luis Crespo-Picazo, Julio Cortijo, and Andreas Fahlman

      To provide new insight into the pathophysiological mechanisms underlying gas emboli (GE) in bycaught loggerhead sea turtles (Caretta caretta), we investigated the vasoactive characteristics of the pulmonary and systemic arteries, and the lung parenchyma (LP). Tissues were opportunistically excised from recently dead animals for in vitro studies of vasoactive responses to four different neurotransmitters: acetylcholine (ACh; parasympathetic), serotonin (5HT), adrenaline (Adr; sympathetic) and histamine. The significant amount of smooth muscle in the LP contracted in response to ACh, Adr and histamine. The intrapulmonary and systemic arteries contracted under both parasympathetic and sympathetic stimulation and when exposed to 5HT. However, proximal extrapulmonary arterial (PEPA) sections contracted in response to ACh and 5HT, whereas Adr caused relaxation. In sea turtles, the relaxation in the pulmonary artery was particularly pronounced at the level of the pulmonary artery sphincter (PASp), where the vessel wall was highly muscular. For comparison, we also studied tissue response in freshwater sliders turtles (Trachemys scripta elegans). Both PEPA and LP from freshwater sliders contracted in response to 5HT, ACh and also Adr. We propose that in sea turtles, the dive response (parasympathetic tone) constricts the PEPA, LP and PASp, causing a pulmonary shunt and limiting gas uptake at depth, which reduces the risk of GE during long and deep dives. Elevated sympathetic tone caused by forced submersion during entanglement with fishing gear increases the pulmonary blood flow causing an increase in N2 uptake, potentially leading to the formation of blood and tissue GE at the surface. These findings provide potential physiological and anatomical explanations on how these animals have evolved a cardiac shunt pattern that regulates gas exchange during deep and prolonged diving.
      PubDate: 2018-12-04T00:57:37-08:00
      DOI: 10.1242/jeb.179820
      Issue No: Vol. 221, No. 23 (2018)
  • Bite force and cranial bone strain in four species of lizards [RESEARCH
    • Authors: Ross, C. F; Porro, L. B, Herrel, A, Evans, S. E, Fagan, M. J.
      Abstract: Callum F. Ross, Laura B. Porro, Anthony Herrel, Susan E. Evans, and Michael J. Fagan

      In vivo bone strain data provide direct evidence of strain patterns in the cranium during biting. Compared with those in mammals, in vivo bone strains in lizard skulls are poorly documented. This paper presents strain data from the skulls of Anolis equestris, Gekko gecko, Iguana iguana and Salvator merianae during transducer biting. Analysis of variance was used to investigate effects of bite force, bite point, diet, cranial morphology and cranial kinesis on strain magnitude. Within individuals, the most consistent determinants of variance in bone strain magnitude were gauge location and bite point, with the importance of bite force varying between individuals. Inter-site variance in strain magnitude – strain gradient – was present in all individuals and varied with bite point. Between individuals within species, variance in strain magnitude was driven primarily by variation in bite force, not gauge location or bite point, suggesting that inter-individual variation in patterns of strain magnitude is minimal. Between species, variation in strain magnitude was significantly impacted by bite force and species membership, as well as by interactions between gauge location, species and bite point. Independent of bite force, species differences in cranial strain magnitude may reflect selection for different cranial morphology in relation to feeding function, but what these performance criteria are is not clear. The relatively low strain magnitudes in Iguana and Uromastyx compared with those in other lizards may be related to their herbivorous diet. Cranial kinesis and the presence or absence of postorbital and supratemporal bars are not important determinants of inter-specific variation in strain magnitude.
      PubDate: 2018-12-04T00:57:37-08:00
      DOI: 10.1242/jeb.180240
      Issue No: Vol. 221, No. 23 (2018)
  • How do baleen whales stow their filter' A comparative biomechanical
           analysis of baleen bending [RESEARCH ARTICLE]
    • Authors: Werth, A. J; Rita, D, Rosario, M. V, Moore, M. J, Sformo, T. L.
      Abstract: Alexander J. Werth, Diego Rita, Michael V. Rosario, Michael J. Moore, and Todd L. Sformo

      Bowhead and right whale (balaenid) baleen filtering plates, longer in vertical dimension (≥3–4 m) than the closed mouth, presumably bend during gape closure. This has not been observed in live whales, even with scrutiny of video-recorded feeding sequences. To determine what happens to the baleen during gape closure, we conducted an integrative, multifactorial study including materials testing, functional (flow tank and kinematic) testing and histological examination. We measured baleen bending properties along the dorsoventral length of plates and anteroposterior location within a rack of plates via mechanical (axial bending, composite flexure, compression and tension) tests of hydrated and air-dried tissue samples from balaenid and other whale baleen. Balaenid baleen is remarkably strong yet pliable, with ductile fringes, and low stiffness and high elasticity when wet; it likely bends in the closed mouth when not used for filtration. Calculation of flexural modulus from stress/strain experiments shows that the balaenid baleen is slightly more flexible where it emerges from the gums and at its ventral terminus, but kinematic analysis indicates plates bend evenly along their whole length. Fin and humpback whale baleen has similar material properties but less flexibility, with no dorsoventral variation. The internal horn tubes have greater external and hollow luminal diameter but lower density in the lateral relative to medial baleen of bowhead and fin whales, suggesting a greater capacity for lateral bending. Baleen bending has major consequences not only for feeding morphology and energetics but also for conservation given that entanglement in fishing gear is a leading cause of whale mortality.
      PubDate: 2018-12-04T00:57:37-08:00
      DOI: 10.1242/jeb.189233
      Issue No: Vol. 221, No. 23 (2018)
  • Vultures respond to challenges of near-ground thermal soaring by varying
           bank angle [RESEARCH ARTICLE]
    • Authors: Williams, H. J; Duriez, O, Holton, M. D, Dell'Omo, G, Wilson, R. P, Shepard, E. L. C.
      Abstract: Hannah J. Williams, Olivier Duriez, Mark D. Holton, Giacomo Dell'Omo, Rory P. Wilson, and Emily L. C. Shepard

      Many large birds rely on thermal soaring flight to travel cross-country. As such, they are under selective pressure to minimise the time spent gaining altitude in thermal updrafts. Birds should be able to maximise their climb rates by maintaining a position close to the thermal core through careful selection of bank angle and airspeed; however, there have been few direct measurements of either parameter. Here, we apply a novel methodology to quantify the bank angles selected by soaring birds using on-board magnetometers. We couple these data with airspeed measurements to parameterise the soaring envelope of two species of Gyps vulture, from which it is possible to predict ‘optimal’ bank angles. Our results show that these large birds respond to the challenges of gaining altitude in the initial phase of the climb, where thermal updrafts are weak and narrow, by adopting relatively high, and conserved, bank angles (25–35 deg). The bank angle decreased with increasing altitude, in a manner that was broadly consistent with a strategy of maximising the rate of climb. However, the lift coefficients estimated in our study were lower than those predicted by theoretical models and wind-tunnel studies. Overall, our results highlight how the relevant currency for soaring performance changes within individual climbs: when thermal radius is limiting, birds vary bank angle and maintain a constant airspeed, but speed increases later in the climb in order to respond to decreasing air density.
      PubDate: 2018-12-03T00:56:25-08:00
      DOI: 10.1242/jeb.174995
      Issue No: Vol. 221, No. 23 (2018)
  • Hydrodynamics of linear acceleration in bluegill sunfish, Lepomis
           macrochirus [RESEARCH ARTICLE]
    • Authors: Wise, T. N; Schwalbe, M. A. B, Tytell, E. D.
      Abstract: Tyler N. Wise, Margot A. B. Schwalbe, and Eric D. Tytell

      In their natural habitat, fish rarely swim steadily. Instead they frequently accelerate and decelerate. Relatively little is known about how fish produce extra force for acceleration in routine swimming behavior. In this study, we examined the flow around bluegill sunfish Lepomis macrochirus during steady swimming and during forward acceleration, starting at a range of initial swimming speeds. We found that bluegill produce vortices with higher circulation during acceleration, indicating a higher force per tail beat, but they do not substantially redirect the force. We quantified the flow patterns using high speed video and particle image velocimetry and measured acceleration with small inertial measurement units attached to each fish. Even in steady tail beats, the fish accelerates slightly during each tail beat, and the magnitude of the acceleration varies. In steady tail beats, however, a high acceleration is followed by a lower acceleration or a deceleration, so that the swimming speed is maintained; in unsteady tail beats, the fish maintains the acceleration over several tail beats, so that the swimming speed increases. We can thus compare the wake and kinematics during single steady and unsteady tail beats that have the same peak acceleration. During unsteady tail beats when the fish accelerates forward for several tail beats, the wake vortex forces are much higher than those at the same acceleration during single tail beats in steady swimming. The fish also undulates its body at higher amplitude and frequency during unsteady tail beats. These kinematic changes likely increase the fluid dynamic added mass of the body, increasing the forces required to sustain acceleration over several tail beats. The high amplitude and high frequency movements are also likely required to generate the higher forces needed for acceleration. Thus, it appears that bluegill sunfish face a trade-off during acceleration: the body movements required for acceleration also make it harder to accelerate.
      Keywords: Comparative biomechanics of movement
      PubDate: 2018-11-30T00:48:57-08:00
      DOI: 10.1242/jeb.190892
      Issue No: Vol. 221, No. 23 (2018)
  • High accuracy at low frequency: detailed behavioural classification from
           accelerometer data [RESEARCH ARTICLE]
    • Authors: Tatler, J; Cassey, P, Prowse, T. A. A.
      Abstract: Jack Tatler, Phillip Cassey, and Thomas A. A. Prowse

      Accelerometers are a valuable tool for studying animal behaviour and physiology where direct observation is unfeasible. However, giving biological meaning to multivariate acceleration data is challenging. Here, we describe a method that reliably classifies a large number of behaviours using tri-axial accelerometer data collected at the low sampling frequency of 1 Hz, using the dingo (Canis dingo) as an example. We used out-of-sample validation to compare the predictive performance of four commonly used classification models (random forest, k-nearest neighbour, support vector machine, and naïve Bayes). We tested the importance of predictor variable selection and moving window size for the classification of each behaviour and overall model performance. Random forests produced the highest out-of-sample classification accuracy, with our best-performing model predicting 14 behaviours with a mean accuracy of 87%. We also investigated the relationship between overall dynamic body acceleration (ODBA) and the activity level of each behaviour, given the increasing use of ODBA in ecophysiology as a proxy for energy expenditure. ODBA values for our four ‘high activity’ behaviours were significantly greater than all other behaviours, with an overall positive trend between ODBA and intensity of movement. We show that a random forest model of relatively low complexity can mitigate some major challenges associated with establishing meaningful ecological conclusions from acceleration data. Our approach has broad applicability to free-ranging terrestrial quadrupeds of comparable size. Our use of a low sampling frequency shows potential for deploying accelerometers over extended time periods, enabling the capture of invaluable behavioural and physiological data across different ontogenies.
      PubDate: 2018-11-29T00:56:11-08:00
      DOI: 10.1242/jeb.184085
      Issue No: Vol. 221, No. 23 (2018)
  • Water pH limits extracellular but not intracellular pH compensation in the
           CO2-tolerant freshwater fish Pangasianodon hypophthalmus [SHORT
    • Authors: Sackville, M. A; Shartau, R. B, Damsgaard, C, Hvas, M, Phuong, L. M, Wang, T, Bayley, M, Thanh Huong, D. T, Phuong, N. T, Brauner, C. J.
      Abstract: Michael A. Sackville, Ryan B. Shartau, Christian Damsgaard, Malthe Hvas, Le My Phuong, Tobias Wang, Mark Bayley, Do Thi Thanh Huong, Nguyen Thanh Phuong, and Colin J. Brauner

      Preferentially regulating intracellular pH (pHi) confers exceptional CO2 tolerance on fish, but is often associated with reductions in extracellular pH (pHe) compensation. It is unknown whether these reductions are due to intrinsically lower capacities for pHe compensation, hypercarbia-induced reductions in water pH or other factors. To test how water pH affects capacities and strategies for pH compensation, we exposed the CO2-tolerant fish Pangasianodon hypophthalmus to 3 kPa PCO2 for 20 h at an ecologically relevant water pH of 4.5 or 5.8. Brain, heart and liver pHi was preferentially regulated in both treatments. However, blood pHe compensation was severely reduced at water pH 4.5 but not 5.8. This suggests that low water pH limits acute pHe but not pHi compensation in fishes preferentially regulating pHi. Hypercarbia-induced reductions in water pH might therefore underlie the unexplained reductions to pHe compensation in fishes preferentially regulating pHi, and may increase selection for preferential pHi regulation.
      PubDate: 2018-11-28T07:57:13-08:00
      DOI: 10.1242/jeb.190413
      Issue No: Vol. 221, No. 23 (2018)
  • MicroRNAs regulate survival in oxygen-deprived environments [RESEARCH
    • Authors: English, S. G; Hadj-Moussa, H, Storey, K. B.
      Abstract: Simon G. English, Hanane Hadj-Moussa, and Kenneth B. Storey

      Some animals must endure prolonged periods of oxygen deprivation to survive. One such extreme model is the northern crayfish (Orconectes virilis), that regularly survives year-round hypoxic and anoxic stresses in its warm stagnant summer waters and in its cold, ice-locked winter waters. To elucidate the molecular underpinnings of anoxia resistance in this natural model, we surveyed the expression profiles of 76 highly conserved microRNAs in crayfish hepatopancreas and tail muscle from normoxic, acute 2 h anoxia, and chronic 20 h anoxia exposures. MicroRNAs are known to regulate a diverse array of cellular functions required for environmental stress adaptations, and here we explored their role in anoxia tolerance. The tissue-specific anoxia responses observed herein, with 22 anoxia-responsive microRNAs in the hepatopancreas and only four in muscle, suggest that microRNAs facilitate a reprioritization of resources to preserve crucial organ functions. Bioinformatic microRNA target enrichment analysis predicted that the anoxia-downregulated microRNAs in hepatopancreas targeted Hippo signalling, suggesting that cell proliferation and apoptotic signalling are highly regulated in this liver-like organ during anoxia. Compellingly, miR-125-5p, miR-33-5p and miR-190-5p, all known to target the master regulator of oxygen deprivation responses HIF1 (hypoxia inducible factor-1), were anoxia downregulated in the hepatopancreas. The anoxia-increased transcript levels of the oxygen-dependent subunit HIF1α highlight a potential critical role for miRNA-HIF targeting in facilitating a successful anoxia response. Studying the cytoprotective mechanisms in place to protect against the challenges associated with surviving in oxygen-poor environments is critical to elucidating the vast and substantial role of microRNAs in the regulation of metabolism and stress in aquatic invertebrates.
      PubDate: 2018-11-28T07:57:13-08:00
      DOI: 10.1242/jeb.190579
      Issue No: Vol. 221, No. 23 (2018)
  • Spectral sensitivity in ray-finned fishes: diversity, ecology and shared
           descent [RESEARCH ARTICLE]
    • Authors: Schweikert, L. E; Fitak, R. R, Caves, E. M, Sutton, T. T, Johnsen, S.
      Abstract: Lorian E. Schweikert, Robert R. Fitak, Eleanor M. Caves, Tracey T. Sutton, and Sönke Johnsen

      A major goal of sensory ecology is to identify factors that underlie sensory-trait variation. One open question centers on why fishes show the greatest diversity among vertebrates in their capacity to detect color (i.e. spectral sensitivity). Over the past several decades, max values (photoreceptor class peak sensitivity) and chromacy (photoreceptor class number) have been cataloged for hundreds of fish species, yet the ecological basis of this diversity and the functional significance of high chromacy levels (e.g. tetra- and pentachromacy) remain unclear. In this study, we examined phylogenetic, physiological and ecological patterns of spectral sensitivity of ray-finned fishes (Actinoptergyii) via a meta-analysis of data compiled from 213 species. Across the fishes sampled, our results indicate that trichromacy is most common, ultraviolet max values are not found in monochromatic or dichromatic species, and increasing chromacy, including from tetra- to pentachromacy, significantly increases spectral sensitivity range. In an ecological analysis, multivariate phylogenetic latent liability modeling was performed to analyze correlations between chromacy and five hypothesized predictors (depth, habitat, diet, body coloration, body size). In a model not accounting for phylogenetic relatedness, each predictor with the exception of habitat significantly correlated with chromacy: a positive relationship in body color and negative relationships with body size, diet and depth. However, after phylogenetic correction, the only remaining correlated predictor was depth. The findings of this study indicate that phyletic heritage and depth are important factors in fish spectral sensitivity and impart caution about excluding phylogenetic comparative methods in studies of sensory trait variation.
      PubDate: 2018-11-27T07:54:32-08:00
      DOI: 10.1242/jeb.189761
      Issue No: Vol. 221, No. 23 (2018)
  • Glucocorticoid-temperature association is shaped by foraging costs in
           individual zebra finches [SHORT COMMUNICATION]
    • Authors: Jimeno, B; Hau, M, Verhulst, S.
      Abstract: Blanca Jimeno, Michaela Hau, and Simon Verhulst

      Glucocorticoid (GC) levels vary with environmental conditions, but the functional interpretation of GC variation remains contentious. A primary function is thought to be metabolic, mobilizing body reserves to match energetic demands. This view is supported by temperature-dependent GC levels, although reports of this effect show unexplained heterogeneity. We hypothesized that the temperature effect on GC concentrations will depend on food availability through its effect on the energy spent to gather the food needed for thermoregulation. We tested this hypothesis in zebra finches living in outdoor aviaries with manipulated foraging conditions (i.e. easy versus hard), by relating within-individual differences in baseline GCs between consecutive years to differences in ambient temperature. In agreement with our hypothesis, we found the GC–temperature association to be significantly steeper in the hard foraging environment. This supports the metabolic explanation of GC variation, underlining the importance of accounting for variation in energy expenditure when interpreting GC variation.
      PubDate: 2018-11-27T07:52:31-08:00
      DOI: 10.1242/jeb.187880
      Issue No: Vol. 221, No. 23 (2018)
  • Correction: Size-dependent physiological responses of the branching coral
           Pocillopora verrucosa to elevated temperature and PCO2
           (doi:10.1242/jeb.146381) [CORRECTION]
    • Authors: Edmunds, P. J; Burgess, S. C.
      Abstract: Peter J. Edmunds and Scott C. Burgess

      PubDate: 2018-11-27T07:52:31-08:00
      DOI: 10.1242/jeb.194753
      Issue No: Vol. 221, No. 23 (2018)
  • Common guillemot (Uria aalge) eggs are not self-cleaning [RESEARCH
    • Authors: Jackson, D; Thompson, J. E, Hemmings, N, Birkhead, T. R.
      Abstract: Duncan Jackson, Jamie E. Thompson, Nicola Hemmings, and Timothy R. Birkhead

      Birds are arguably the most evolutionarily successful extant vertebrate taxon, in part because of their ability to reproduce in virtually all terrestrial habitats. Common guillemots, Uria aalge, incubate their single egg in an unusual and harsh environment; on exposed cliff ledges, without a nest, and in close proximity to conspecifics. As a consequence, the surface of guillemot eggshells is frequently contaminated with faeces, dirt, water and other detritus, which may impede gas exchange or facilitate microbial infection of the developing embryo. Despite this, guillemot chicks survive incubation and hatch from eggs heavily covered with debris. To establish how guillemot eggs cope with external debris, we tested three hypotheses: (1) contamination by debris does not reduce gas exchange efficacy of the eggshell to a degree that may impede normal embryo development; (2) the guillemot eggshell surface is self-cleaning; (3) shell accessory material (SAM) prevents debris from blocking pores, allowing relatively unrestricted gas diffusion across the eggshell. We showed that natural debris reduces the conductance of gases across the guillemot eggshell by blocking gas exchange pores. Despite this problem, we found no evidence that guillemot eggshells are self-cleaning, but instead showed that the presence of SAM on the eggshell surface largely prevents pore blockages from occurring. Our results demonstrate that SAM is a crucial feature of the eggshell surface in a species with eggs that are frequently in contact with debris, acting to minimise pore blockages and thus ensure a sufficient rate of gas diffusion for embryo development.
      PubDate: 2018-11-27T00:47:16-08:00
      DOI: 10.1242/jeb.188466
      Issue No: Vol. 221, No. 23 (2018)
  • Mucky guillemot eggs are definitely not self-cleaning [INSIDE JEB]
    • Authors: Knight K.
      Abstract: Kathryn Knight

      PubDate: 2018-11-27T00:47:16-08:00
      DOI: 10.1242/jeb.194720
      Issue No: Vol. 221, No. 23 (2018)
  • Adaptive frequency shifts of echolocation sounds in Miniopterus
           fuliginosus according to the frequency-modulated pattern of jamming sounds
    • Authors: Maitani, Y; Hase, K, Kobayasi, K. I, Hiryu, S.
      Abstract: Yosuke Maitani, Kazuma Hase, Kohta I. Kobayasi, and Shizuko Hiryu

      When flying in a group, echolocating bats have to separate their own echoes from pulses and echoes belonging to other individuals to extract only the information necessary for their own navigation. Previous studies have demonstrated that frequency-modulated (FM) bats change the terminal frequencies (TFs) of downward FM pulses under acoustic interference. However, it is not yet clear which acoustic characteristics of the jamming signals induce the TF shift according to the degree of acoustic interference. In this study, we examined changes in the acoustic characteristics of pulses emitted by Miniopterus fuliginosus while presenting jamming stimuli with different FM patterns to the bat flying alone. Bats significantly altered their TFs when responding to downward (dExp) and upward (uExp) exponential FM sounds as well as to a constant-frequency (CF) stimulus, by approximately 1–2 kHz (dExp: 2.1±0.9 kHz; uExp: 1.7±0.3 kHz; CF: 1.3±0.4 kHz) but not for linear FM sounds. The feature common to the spectra of these three jamming stimuli is a spectrum peak near the TF frequency, demonstrating that the bats shift the TF to avoid masking of jamming sounds on the TF frequency range. These results suggest that direct frequency masking near the TF frequency range induces the TF shift, which simultaneously decreases the similarity between their own echolocation sounds and jamming signals.
      PubDate: 2018-11-26T04:54:22-08:00
      DOI: 10.1242/jeb.188565
      Issue No: Vol. 221, No. 23 (2018)
  • Latency for facultative expression of male-typical courtship behaviour by
           female bluehead wrasses depends on social rank: the 'priming/gating
           hypothesis [RESEARCH ARTICLE]
    • Authors: Price, S. M; Luong, K, Bell, R. S, Rose, G. J.
      Abstract: Sarah M. Price, Kyphuong Luong, Rickesha S. Bell, and Gary J. Rose

      Although socially controlled sex transformation in fishes is well established, the underlying mechanisms are not well understood. Particularly enigmatic is behavioural transformation, in which fish can rapidly switch from exhibiting female to male-typical courtship behaviours following removal of ‘supermales’. Bluehead wrasses are a model system for investigating environmental control of sex determination, particularly the social control of sex transformation. Here, we show that the onset of this behavioural transformation was delayed in females that occupied low-ranking positions in the female dominance hierarchy. We also establish that expression of male-typical courtship behaviours in competent initial-phase (IP) females is facultative and gated by the presence of terminal-phase (TP) males. Dominant females displayed reliable TP male-typical courtship behaviours within approximately 2 days of the removal of a TP male; immediately following reintroduction of the TP male, however, females reverted back to female-typical behaviours. These results demonstrate a remarkable plasticity of sexual behaviour and support a ‘priming/gating’ hypothesis for the control of behavioural transformation in bluehead wrasses.
      Keywords: Neuroethology
      PubDate: 2018-11-26T03:54:33-08:00
      DOI: 10.1242/jeb.180901
      Issue No: Vol. 221, No. 23 (2018)
  • Evidence that Rh proteins in the anal papillae of the freshwater mosquito
           Aedes aegypti are involved in the regulation of acid-base balance in
           elevated salt and ammonia environments [RESEARCH ARTICLE]
    • Authors: Durant, A. C; Donini, A.
      Abstract: Andrea C. Durant and Andrew Donini

      Aedes aegypti commonly inhabit ammonia-rich sewage effluents in tropical regions of the world where the adults are responsible for the spread of disease. Studies have shown the importance of the anal papillae of A. aegypti in ion uptake and ammonia excretion. The anal papillae express ammonia transporters and Rhesus (Rh) proteins which are involved in ammonia excretion and studies have primarily focused on understanding these mechanisms in freshwater. In this study, effects of rearing larvae in salt (5 mmol l–1 NaCl) or ammonia (5 mmol l–1 NH4Cl) on physiological endpoints of ammonia and ion regulation were assessed. In anal papillae of NaCl-reared larvae, Rh protein expression increased, NHE3 transcript abundance decreased and NH4+ excretion increased, and this coincided with decreased hemolymph [NH4+] and pH. We propose that under these conditions, larvae excrete more NH4+ through Rh proteins as a means of eliminating acid from the hemolymph. In anal papillae of NH4Cl-reared larvae, expression of an apical ammonia transporter and the Rh proteins decreased, the activities of NKA and VA decreased and increased, respectively, and this coincided with hemolymph acidification. The results present evidence for a role of Rh proteins in acid–base balance in response to elevated levels of salt, whereby ammonia is excreted as an acid equivalent.
      PubDate: 2018-11-26T02:41:10-08:00
      DOI: 10.1242/jeb.186866
      Issue No: Vol. 221, No. 23 (2018)
  • Genetic accommodation and the role of ancestral plasticity in the
           evolution of insect eusociality [COMMENTARY]
    • Authors: Jones, B. M; Robinson, G. E.
      Abstract: Beryl M. Jones and Gene E. Robinson

      For over a century, biologists have proposed a role for phenotypic plasticity in evolution, providing an avenue for adaptation in addition to ‘mutation-first’ models of evolutionary change. According to the various versions of this idea, the ability of organisms to respond adaptively to their environment through phenotypic plasticity may lead to novel phenotypes that can be screened by natural selection. If these initially environmentally induced phenotypes increase fitness, then genetic accommodation can lead to allele frequency change, influencing the expression of those phenotypes. Despite the long history of ‘plasticity-first’ models, the importance of genetic accommodation in shaping evolutionary change has remained controversial – it is neither fully embraced nor completely discarded by most evolutionary biologists. We suggest that the lack of acceptance of genetic accommodation in some cases is related to a lack of information on its molecular mechanisms. However, recent reports of epigenetic transgenerational inheritance now provide a plausible mechanism through which genetic accommodation may act, and we review this research here. We also discuss current evidence supporting a role for genetic accommodation in the evolution of eusociality in social insects, which have long been models for studying the influence of the environment on phenotypic variation, and may be particularly good models for testing hypotheses related to genetic accommodation. Finally, we introduce ‘eusocial engineering’, a method by which novel social phenotypes are first induced by environmental modification and then studied mechanistically to understand how environmentally induced plasticity may lead to heritable changes in social behavior. We believe the time is right to incorporate genetic accommodation into models of the evolution of complex traits, armed with new molecular tools and a better understanding of non-genetic heritable elements.
      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.153163
      Issue No: Vol. 221, No. 23 (2018)
  • Size slows animals response to surprise [OUTSIDE JEB]
    • Authors: Stenum J.
      Abstract: Jan Stenum

      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.170233
      Issue No: Vol. 221, No. 23 (2018)
  • Birds and bats: masters of hovering [OUTSIDE JEB]
    • Authors: Stawski C.
      Abstract: Clare Stawski

      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.170282
      Issue No: Vol. 221, No. 23 (2018)
  • Some like it warm - usually women [OUTSIDE JEB]
    • Authors: Regan M. D.
      Abstract: Matthew D. Regan

      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.170290
      Issue No: Vol. 221, No. 23 (2018)
  • A breath of fresh air for lungless salamanders [OUTSIDE JEB]
    • Authors: Joyce W.
      Abstract: William Joyce

      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.170308
      Issue No: Vol. 221, No. 23 (2018)
  • Potential role of the anterior lateral line in sound localization in
           toadfish (Opsanus tau) [RESEARCH ARTICLE]
    • Authors: Cardinal, E. A; Radford, C. A, Mensinger, A. F.
      Abstract: Emily A. Cardinal, Craig A. Radford, and Allen F. Mensinger

      Male oyster toadfish (Opsanus tau) acoustically attract females to nesting sites using a boatwhistle call. The rapid speed of sound underwater combined with the close proximity of the otolithic organs makes inner ear interaural time differences an unlikely mechanism to localize sound. To determine the role that the mechanosensory lateral line may play in sound localization, microwire electrodes were bilaterally implanted into the anterior lateral line nerve to record neural responses to vibrational stimuli. Highest spike rates and strongest phase-locking occurred at distances close to the fish and decreased as the stimulus was moved further from the fish. Bilateral anterior lateral line neuromasts displayed differential directional sensitivity to incoming vibrational stimuli, which suggests the potential for the lateral line to be used for sound localization in the near field. The present study also demonstrates that the spatially separated neuromasts of the toadfish may provide sufficient time delays between sensory organs for determining sound localization cues. Multimodal sensory input processing through both the inner ear (far field) and lateral line (near field) may allow for effective sound localization in fish.
      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.180679
      Issue No: Vol. 221, No. 23 (2018)
  • Endotoxin rapidly desensitizes the gonads to kisspeptin-induced
           luteinizing hormone release in male Siberian hamsters (Phodopus sungorus)
    • Authors: Long, K. L. P; Bailey, A. M, Greives, T. J, Legan, S. J, Demas, G. E.
      Abstract: Kimberly L. P. Long, Allison M. Bailey, Timothy J. Greives, Sandra J. Legan, and Gregory E. Demas

      Activation of the immune system induces rapid reductions in hypothalamic-pituitary–gonadal (HPG) axis activity, which in turn decreases secretion of sex steroids. This response is likely adaptive for survival by temporarily inhibiting reproduction to conserve energy; however, the physiological mechanisms controlling this response remain unclear. The neuropeptide kisspeptin is a candidate to mediate the decrease in sex hormones seen during sickness through its key regulation of the HPG axis. In this study, the effects of acute immune activation on the response to kisspeptin were assessed in male Siberian hamsters (Phodopus sungorus). Specifically, an immune response was induced in animals by a single treatment of lipopolysaccharide (LPS), and reproductive hormone concentrations were determined in response to subsequent injections of exogenous kisspeptin. Saline-treated controls showed a robust increase in circulating testosterone in response to kisspeptin; however, this response was blocked in LPS-treated animals. Circulating luteinizing hormone (LH) levels were elevated in response to kisspeptin in both LPS- and saline-treated groups and, thus, were unaffected by LPS treatment, suggesting gonad-level inhibition of testosterone release despite central HPG activation. In addition, blockade of glucocorticoid receptors by mifepristone did not attenuate the LPS-induced inhibition of testosterone release, suggesting that circulating glucocorticoids do not mediate this phenomenon. Collectively, these findings reveal that acute endotoxin exposure rapidly renders the gonads less sensitive to HPG stimulation, thus effectively inhibiting sex hormone release. More broadly, these results shed light on the effects of immune activation on the HPG axis and help elucidate the mechanisms controlling energy allocation and reproduction.
      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.185504
      Issue No: Vol. 221, No. 23 (2018)
  • High experience levels delay recruitment but promote simultaneous
           time-memories in honey bee foragers [RESEARCH ARTICLE]
    • Authors: Van Nest, B. N; Otto, M. W, Moore, D.
      Abstract: Byron N. Van Nest, Matthew W. Otto, and Darrell Moore

      Honey bee (Apis mellifera) foragers can remember both the location and time of day food is collected and, even in the absence of a reward, reconnoiter the food source at the appropriate time on subsequent days. This spatiotemporal memory (time-memory) is linked to the circadian clock and enables foragers to synchronize their behavior with floral nectar secretion rhythms, thus eliminating the need to rediscover productive food sources each day. Here, we asked whether the establishment of one time-memory influences the formation of another time-memory at the same time of day. In other words, can two time-place memories with the same ‘time-stamp’ co-exist' We simultaneously trained two groups of foragers from a single hive to two separate feeders at the same restricted time of day. After 5 days of training, one feeder was shut off. The second feeder continued being productive 4 more days. Our results showed that (1) foragers with high experience levels at the first source were significantly more likely than low-experience foragers to maintain fidelity to their original source and resist recruitment to the alternative source, (2) nearly one-third of foragers demonstrated multiple, overlapping time-memories by visiting both feeders at the correct time and (3) significantly more high-experience than low-experience foragers exhibited this multitasking behavior. The ability to maintain and act upon two different, yet contemporaneous, time-memories gives the forager bee a previously unknown level of versatility in attending to multiple food sources. These findings have major implications for understanding the formation and management of circadian spatiotemporal memories.
      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.187336
      Issue No: Vol. 221, No. 23 (2018)
  • Serotonin: octopus love potion' [OUTSIDE JEB]
    • Authors: Nadler L. E.
      Abstract: Lauren E. Nadler

      PubDate: 2018-11-26T01:05:44-08:00
      DOI: 10.1242/jeb.193698
      Issue No: Vol. 221, No. 23 (2018)
  • Social stress increases plasma cortisol and reduces forebrain cell
           proliferation in subordinate male zebrafish (Danio rerio) [RESEARCH
    • Authors: Tea, J; Alderman, S. L, Gilmour, K. M.
      Abstract: Jonathan Tea, Sarah L. Alderman, and Kathleen M. Gilmour

      Many animals, including zebrafish (Danio rerio), form social hierarchies through competition for limited resources. Socially subordinate fish may experience chronic stress, leading to prolonged elevation of the glucocorticoid stress hormone cortisol. Since elevated cortisol levels can impair neurogenesis, the present study tested the hypothesis that social stress suppresses cell proliferation in the telencephalon of subordinate zebrafish via a cortisol-mediated mechanism. Cell proliferation was assessed using incorporation of the thymidine analogue, 5-bromo-2'-deoxyuridine (BrdU). After 48 and 96 h of social interaction, subordinate male zebrafish exhibited elevated plasma cortisol concentrations and significantly lower numbers of BrdU+ cells in the dorsal but not ventral regions of the telencephalon compared to dominant or group-housed control male fish. After a two-week recovery in a familiar group of conspecifics, the number of BrdU+ cells that co-labeled with a neuronal marker (NeuN) was modestly reduced in previously subordinate male fish, suggesting that the reduction of cell proliferation during social stress may result in fewer cells recruited into the neuronal population. In contrast to male social hierarchies, subordinate female zebrafish did not experience elevated plasma cortisol, and the numbers of BrdU+ cells in the dorsal telencephalon were comparable among dominant, subordinate, and group-housed control female fish. Treating male zebrafish with metyrapone, a cortisol synthesis inhibitor, blocked the cortisol response to social subordination and attenuated the suppression of brain cell proliferation in the dorsal telencephalon of subordinate fish. Collectively, these data support a role for cortisol in regulating adult neurogenesis in the telencephalon of male zebrafish during social stress.
      PubDate: 2018-12-10T02:10:01-08:00
      DOI: 10.1242/jeb.194894
  • Nitrogen handling in the elasmobranch gut: a role for microbial urease
    • Authors: Wood, C. M; Liew, H. J, De Boeck, G, Hoogenboom, J. L, Anderson, W. G.
      Abstract: Chris M. Wood, Hon Jung Liew, Gudrun De Boeck, J. Lisa Hoogenboom, and W. Gary Anderson

      Ureotelic elasmobranchs require nitrogen for both protein growth and urea-based osmoregulation, and therefore are probably nitrogen-limited in nature. Mechanisms exist for retaining and/or scavenging nitrogen at gills, kidney, rectal gland, and gut, but as yet, the latter are not well characterized. Intestinal sac preparations of the Pacific spiny dogfish shark (Squalus acanthias suckleyi) incubated in vitro strongly reabsorbed urea from the lumen after feeding, but mucosal fluid ammonia concentrations increased with incubation time. Phloretin (0.25 mmol L–1, which blocked urea reabsorption) greatly increased the rate of ammonia accumulation in the lumen. A sensitive [14C]urea-based assay was developed to examine the potential role of microbial urease in this ammonia production. Urease activity was detected in chyme/intestinal fluid and intestinal epithelial tissue of both fed and fasted sharks. Urease was not present in gall-bladder bile. Urease activities were highly variable among animals, but generally greater in chyme than in epithelia, and greater in fed than in fasted sharks. Comparable urease activities were found in chyme and epithelia of the Pacific spotted ratfish (Hydrolagus colliei), a ureotelic holocephalan, but were much lower in ammonotelic teleosts. Urease activity in dogfish chyme was inhibited by acetohydroxamic acid (1 mmol L–1) and by boiling. Treatment of dogfish gut sac preparations with acetohydroxamic acid blocked ammonia production, changing net ammonia accumulation into net ammonia absorption. We propose that microbial urease plays an important role in nitrogen handling in the elasmobranch intestine, allowing some urea-N to be converted to ammonia and then reabsorbed for amino acid synthesis or reconversion to urea.
      PubDate: 2018-12-10T02:10:01-08:00
      DOI: 10.1242/jeb.194787
  • Traction reinforcement in prehensile feet of harvestmen (Arachnida,
           Opiliones) [RESEARCH ARTICLE]
    • Authors: Wolff, J. O; Wiegmann, C, Wirkner, C. S, Koehnsen, A, Gorb, S. N.
      Abstract: Jonas O. Wolff, Chantal Wiegmann, Christian S. Wirkner, Alexander Koehnsen, and Stanislav N. Gorb

      Prehensile and gripping organs are recurring structures in different organisms that enhance friction by the reinforcement and redirection of normal forces. The relationship between organ structure and biomechanical performance is poorly understood, despite a broad relevance for microhabitat choice, movement ecology and biomimetics. Here, we present the first study of the biomechanics of prehensile feet in long-legged harvestmen. These arachnids exhibit the strongest sub-division of legs among arthropods, permitting extreme hyper-flexion (i.e. curling up the foot tip). We found that despite the lack of adhesive foot pads, these moderately sized arthropods are able to scale vertical smooth surfaces, if the surface is curved. The comparison of three species of harvestmen differing in leg morphology show that traction reinforcement by foot wrapping depends on the degree of leg sub-division, not leg length. Differences are explained by adaptation to different microhabitats on trees. The exponential increase of foot section length from distal to proximal introduces a gradient of flexibility that permits adaptation to a wide range of surface curvature while maintaining integrity at strong flexion. A pulley system of the claw depressor tendon ensures the controlled flexion of the high number of adesmatic joints in the harvestman foot. These results contribute to the general understanding of foot function in arthropods and showcase an interesting model for the biomimetic engineering of novel transportation systems and surgical probes.
      PubDate: 2018-12-10T02:10:01-08:00
      DOI: 10.1242/jeb.192187
  • Orienting to polarized light at night--matching lunar skylight to
           performance in a nocturnal beetle [RESEARCH ARTICLE]
    • Authors: Foster, J. J; Kirwan, J. D, el Jundi, B, Smolka, J, Khaldy, L, Baird, E, Byrne, M. J, Nilsson, D.-E, Johnsen, S, Dacke, M.
      Abstract: James J. Foster, John D. Kirwan, Basil el Jundi, Jochen Smolka, Lana Khaldy, Emily Baird, Marcus J. Byrne, Dan-Eric Nilsson, Sönke Johnsen, and Marie Dacke

      For polarized light to inform behaviour, the typical range of degrees of polarization observable in the animal's natural environment must be above the threshold for detection and interpretation. Here we present the first investigation of the degree of linear polarization threshold for orientation behaviour in a nocturnal species, with specific reference to the range of degrees of polarization measured in the night sky. An effect of lunar phase on the degree of polarization of skylight was found, with smaller illuminated fractions of the moon's surface corresponding to lower degrees of polarization in the night sky. We found that South African dung beetle Escarabaeus satyrus (Boheman, 1860) can orient to polarized light for a range of degrees of polarization similar to that observed in diurnal insects, reaching a lower threshold between 0.04 and 0.32, possibly as low as 0.11. For degrees of polarization lower than 0.23, as measured on a crescent moon night, orientation performance was considerably weaker than that observed for completely linearly-polarized stimuli, but was nonetheless stronger than in the absence of polarized light.
      PubDate: 2018-12-10T02:10:01-08:00
      DOI: 10.1242/jeb.188532
  • Do arthropods feel anxious during molts' [SHORT COMMUNICATION]
    • Authors: Bacque-Cazenave, J; Berthomieu, M, Cattaert, D, Fossat, P, Delbecque, J. P.
      Abstract: Julien Bacque-Cazenave, Marion Berthomieu, Daniel Cattaert, Pascal Fossat, and Jean Paul Delbecque

      The molting process of arthropods, chiefly controlled by ecdysteroids, is generally considered very stressful. Our previous investigations have shown that crayfish, after having experienced stressing situations, display anxiety-like behavior (ALB), characterized by aversion to light in a dark/light plus-maze (DLPM). In the present experiments, the spontaneous exploratory behavior of isolated crayfish was analyzed in a DLPM at different stages of their molt cycle. All tested animals displayed transitory aversion to light similar to ALB, before and, mostly, after molting, but not during intermolt. Injection of ecdysteroids into intermolt animals elicited ALB after a delay of 4 days, suggesting a long-term, possibly indirect, hormonal effect. Importantly, ecdysteroid-induced ALB was suppressed by the injection of an anxiolytic benzodiazepine. Thus, molts and their hormonal control impose internal stress on crayfish, leading to aversion behavior that has the main characteristics of anxiety. These observations are possibly generalizable to many other arthropods.
      PubDate: 2018-12-10T02:10:01-08:00
      DOI: 10.1242/jeb.186999
  • Hif-1{alpha} paralogs play a role in the hypoxic ventilatory response of
           larval and adult zebrafish (Danio rerio) [RESEARCH ARTICLE]
    • Authors: Mandic, M; Tzaneva, V, Careau, V, Perry, S. F.
      Abstract: Milica Mandic, Velislava Tzaneva, Vincent Careau, and Steve F. Perry

      Hypoxia inducible factor (Hif) 1α, an extensively studied transcription factor, is involved in the regulation of many biological processes in hypoxia including the hypoxic ventilatory response. In zebrafish, there are two paralogs of Hif-1α (Hif-1A and Hif-1B), but little is known about the specific roles or potential sub-functionalization of the paralogs in response to hypoxia. Using knockout lines of Hif-1α paralogs, we examined their involvement in the hypoxic ventilatory response, measured as ventilation frequency (fV) in larval and adult zebrafish (Danio rerio). In wild-type zebrafish, fV increased across developmental time [4 days post fertilization (dpf), 7 dpf, 10 dpf and 15 dpf] in response to hypoxia (55 mmHg). In contrast, the Hif-1B knockout fish did not exhibit an increase in hypoxic fV at 4 dpf. Similar to wild-types, as larvae of all knockout lines developed, the magnitude of fV increased but to a lesser degree than in the wild-type larvae, until 15 dpf at which point there was no difference among the genotypes. In adult zebrafish, only in Hif-1B knockout fish was there an attenuation in fV during sustained exposure to 30 mmHg for 1 h but no effect when exposed for a shorter duration to progressive hypoxia. The mechanism of action of Hif-1α, in part, may be through its downstream target, nitric oxide synthase (NOS), and its product, nitric oxide (NO). Overall, the effect of each Hif-1α paralog on the hypoxic ventilatory response of zebrafish varies over development and is dependent on the type of hypoxic stress.
      PubDate: 2018-12-05T01:07:14-08:00
      DOI: 10.1242/jeb.195198
  • Detailed movement and laterality of fin-biting behaviour with special
           mouth morphology in Genyochromis mento in Lake Malawi [RESEARCH ARTICLE]
    • Authors: Takeuchi, Y; Hata, H, Maruyama, A, Yamada, T, Nishikawa, T, Fukui, M, Zatha, R, Rusuwa, B, Oda, Y.
      Abstract: Yuichi Takeuchi, Hiroki Hata, Atsushi Maruyama, Takuto Yamada, Takuma Nishikawa, Makiko Fukui, Richard Zatha, Bosco Rusuwa, and Yoichi Oda

      Several vertebrates, including fish, exhibit behavioural laterality and associated morphological asymmetry. Laterality may increase individual fitness, and foraging strength, accuracy, and speed. However, little is known about which behaviours are affected by laterality or what fish species exhibit obvious laterality. Previous research on the predatory behaviour of the scale-eating Lake Tanganyika cichlid Perissodus microlepis indicates behavioural laterality that reflects asymmetric jaw morphology. The Lake Malawi cichlid Genyochromis mento feeds on the fins of other fish, a behaviour that G. mento developed independently from the Tanganyikan Perissodini scale-eaters. We investigated stomach contents and behavioural laterality of predation in aquarium to clarify the functional roles and evolution of laterality in cichlids. We also compared the behavioural laterality and mouth asymmetry of G. mento and P. microlepis. The diet of G. mento mostly includes fin fragments, but also scales of several fish species. Most individual G. mento specimens showed significant attack bias favouring the skew mouth direction. However, there was no difference in success rate between attacks from the preferred side and those from the non-preferred side, and no lateralized kinetic elements in predation behaviour. G. mento showed weaker laterality than P. microlepis, partly because of their different feeding habits, the phylogenetic constraints from their shorter evolutionary history, and their origin from ancestor Haplochromini omnivorous/herbivorous species. Taken together, this study provides new insights into the functional roles of behavioural laterality: Predatory fish aiming for prey that show escape behaviours frequently exhibit lateralized behaviour in predation.
      PubDate: 2018-12-03T02:38:40-08:00
      DOI: 10.1242/jeb.191676
  • Interspecific variation in brain mitochondrial complex I and II capacity
           and ROS emission in marine sculpins [RESEARCH ARTICLE]
    • Authors: Lau, G. Y; Richards, J. G.
      Abstract: Gigi Y. Lau and Jeffrey G. Richards

      Environmental hypoxia presents a metabolic challenge for animals because it inhibits mitochondrial respiration and can lead to the generation of reactive oxygen species (ROS). We investigated the interplay between O2 use for aerobic respiration and ROS generation among sculpin fishes (Cottidae, Actinopterygii) that are known to vary in whole-animal hypoxia tolerance. We hypothesized that mitochondria from hypoxia tolerant sculpins would show more efficient O2 use with a higher phosphorylation efficiency and lower ROS emission. We showed that brain mitochondria from more hypoxia tolerant sculpins had lower complex I and higher complex II flux capacities compared with less hypoxia tolerant sculpins, but these differences were not related to variation in phosphorylation efficiency (ADP/O) or mitochondrial coupling (respiratory control ratio). The hypoxia tolerant sculpin had higher mitochondrial H2O2 emission per O2 consumed (H2O2/O2) under oligomycin-induced state 4 conditions compared to less hypoxia tolerant sculpin. An in vitro redox challenge experiment revealed species differences in how well mitochondria defend their glutathione redox status when challenged with high levels of reduced glutathione, but the redox challenge elicited the same H2O2/O2 in all species. Furthermore, in vitro anoxia-recovery lowered absolute H2O2 emission (H2O2/mg mitochondrial protein) in all species and negatively impacted state 3 respiration rates in some species, but the responses were not related to hypoxia tolerance. Overall, we clearly demonstrate a relationship between hypoxia tolerance and complex I and II flux capacities in sculpins, but the differences in complex flux capacity do not appear to be directly related to variation in ROS metabolism.
      PubDate: 2018-12-03T02:38:40-08:00
      DOI: 10.1242/jeb.189407
  • Comparison of spatiotemporal gait characteristics between vertical
           climbing and horizontal walking in primates [RESEARCH ARTICLE]
    • Authors: Granatosky, M. C; Schmitt, D, Hanna, J.
      Abstract: Michael C. Granatosky, Daniel Schmitt, and Jandy Hanna

      During quadrupedal walking, most primates utilize diagonal sequence diagonal couplet gaits, large limb excursions, and hindlimb-biased limb-loading. These gait characteristics are thought to be basal to the Order, but the selective pressure underlying these gait changes remains unknown. Some researchers have examined these characteristics during vertical climbing and propose that primate quadrupedal gait characteristics may have arisen due to the mechanical challenges of moving on vertical supports. Unfortunately, these studies are usually limited in scope and do not account for varying strategies based on body size or phylogeny. Here, we test the hypothesis that the spatiotemporal gait characteristics that are used during horizontal walking in primates are also present during vertical climbing irrespective of body size and phylogeny. We examined footfall patterns, diagonality, speed, and stride length in eight species of primates across a range of body masses. We found that during vertical climbing primates slow down, keep more limbs in contact with the substrate at any one time, and increase the frequency of lateral sequence gaits compared to horizontal walking. Taken together these characteristics are assumed to increase stability during locomotion. Phylogenetic relatedness and body size differences have little influence on locomotor patterns observed across species. These data reject the idea that the suite of spatiotemporal gait features observed in primates during horizontal walking are in some way evolutionarily linked to selective pressures associated with mechanical requirements of vertical climbing. These results also highlight the importance of behavioral flexibility for negotiating the challenges of locomotion in an arboreal environment.
      PubDate: 2018-12-03T02:38:40-08:00
      DOI: 10.1242/jeb.185702
  • The locomotor kinematics and ground reaction forces of walking giraffes
    • Authors: Basu, C; Wilson, A. M, Hutchinson, J. R.
      Abstract: Christopher Basu, Alan M. Wilson, and John R. Hutchinson

      Giraffes (Giraffa camelopardalis Linnaeus 1758) possess specialised anatomy. Their disproportionately elongate limbs and neck confer recognised feeding advantages, but little is known about how their morphology affects locomotor function. In this study, we examined the stride parameters and ground reaction forces from three adult giraffes in a zoological park, across a range of walking speeds. The patterns of GRFs during walking indicate that giraffes, similar to other mammalian quadrupeds, maintain a forelimb-biased weight distribution. The angular excursion of the neck has functional links with locomotor dynamics in giraffes, and was exaggerated at faster speeds. The horizontal accelerations of the neck and trunk were out of phase, compared with the vertical accelerations which were intermediate between in and out of phase. Despite possessing specialised morphology, giraffes’ stride parameters were broadly predicted from dynamic similarity, facilitating the use of other quadrupedal locomotion models to generate testable hypotheses in giraffes.
      PubDate: 2018-12-03T02:38:40-08:00
      DOI: 10.1242/jeb.159277
  • The respiratory mechanics of the yacare caiman (Caiman yacare Daudine)
    • Authors: Reichert, M. N; de Oliveira, P. R. C, Souza, G. M. P. R, Moranza, H. G, Restan, W. A. Z, Abe, A. S, Klein, W, Milsom, W. K.
      Abstract: Michelle N. Reichert, Paulo R. C. de Oliveira, George M. P. R. Souza, Henriette G. Moranza, Wilmer A. Z. Restan, Augusto S. Abe, Wilfried Klein, and William K. Milsom

      The structure and function of crocodilian lungs are unique compared to other reptiles. We examine the extent to which this, and the semi-aquatic lifestyle of crocodilians affect their respiratory mechanics. We measured changes in intratracheal pressure in adult and juvenile caiman (Caiman yacare) during static and dynamic lung volume changes. Respiratory mechanics of juvenile caiman were additionally measured while floating in water and submerged at 30°, 60°, and 90° to the water's surface. The static compliance of the juvenile pulmonary system (2.89±0.22 mL cmH2O 100g–1) was greater than that of adults (1.2±0.41 ml cmH2O 100g–1), suggesting that the system stiffens as the body wall becomes more muscular and keratinized in adults. For both age groups, the lungs were much more compliant than the body wall, offering little resistance to air flow (15.35 and 4.25 for lungs, versus 3.39 and 1.67 mL cmH2O 100g–1 for body wall, in juveniles and adults respectively). Whole system dynamic mechanics decreased with increasing ventilation frequency (fR), but was unaffected by changes in tidal volume (VT). The vast majority of work of breathing was required to overcome elastic forces, however work to overcome resistive forces increased proportionally with fR. Work of breathing was higher in juvenile caiman submerged in water at 90°, due to an increase in work to overcome both elastic and flow resistive forces. The lowest power of breathing was found to occur at high fR and low VT for any given minute ventilation (VE) in caiman of all ages.
      PubDate: 2018-11-29T01:13:48-08:00
      DOI: 10.1242/jeb.193037
  • Dolphin echolocation behaviour during active long-range target approaches
    • Authors: Ladegaard, M; Mulsow, J, Houser, D. S, Jensen, F. H, Johnson, M, Madsen, P. T, Finneran, J. J.
      Abstract: Michael Ladegaard, Jason Mulsow, Dorian S. Houser, Frants Havmand Jensen, Mark Johnson, Peter Teglberg Madsen, and James J. Finneran

      Echolocating toothed whales generally adjust click intensities and rates according to target range to ensure that echoes from targets of interest arrive before a subsequent click is produced, presumably facilitating range estimation from the delay between clicks and returning echoes. However, this click-echo-click paradigm for dolphin biosonar is mostly based on experiments with stationary animals echolocating fixed targets at ranges below ~120 m. Therefore, we trained two bottlenose dolphins instrumented with a sound recording tag to approach a target from ranges up to 400 m and either touch the target (subject TRO) or detect a target orientation change (subject SAY). We show that free-swimming dolphins dynamically increase interclick interval (ICI) out to target ranges of ~100 m. TRO consistently kept ICIs above the two-way travel-time (TWTT) for target ranges shorter than ~100 m, whereas SAY switched between clicking at ICIs above and below the TWTT for target ranges down to ~25 m. Source levels changed on average by 17log10(target range), but with considerable variation for individual slopes (4.1 standard deviations for by-trial random effects), demonstrating that dolphins do not adopt a fixed automatic-gain-control matched to target range. At target ranges exceeding ~100 m, both dolphins frequently switched to click packet production in which interpacket intervals exceeded the TWTT, but ICIs were shorter than the TWTT. This study shows that echolocation following the click-echo-click paradigm is not a fixed echolocation strategy in dolphins, and we demonstrate the first use of click packets for free-swimming dolphins when solving an echolocation task.
      PubDate: 2018-11-26T03:08:27-08:00
      DOI: 10.1242/jeb.189217
  • AMGSEFLamide, a member of a broadly conserved peptide family, modulates
           multiple neural networks in Homarus americanus [RESEARCH ARTICLE]
    • Authors: Dickinson, P. S; Dickinson, E. S, Oleisky, E. R, Rivera, C. D, Stanhope, M. E, Stemmler, E. A, Hull, J. J, Christie, A. E.
      Abstract: Patsy S. Dickinson, Evyn S. Dickinson, Emily R. Oleisky, Cindy D. Rivera, Meredith E. Stanhope, Elizabeth A. Stemmler, J. Joe Hull, and Andrew E. Christie

      Recent genomic/transcriptomic studies have identified a novel peptide family whose members share the carboxyl terminal sequence –GSEFLamide. However, the presence/identity of the predicted isoforms of this peptide group have yet to be confirmed biochemically, and no physiological function has yet been ascribed to any member of this peptide family. To determine the extent to which GSEFLamides are conserved within the Arthropoda, we searched publicly accessible databases for genomic/transcriptomic evidence of their presence. GSEFLamides appear to be highly conserved within the Arthropoda, with the possible exception of the Insecta, in which sequence evidence was limited to the more basal orders. One crustacean in which GSEFLamides have been predicted using transcriptomics is the lobster, Homarus americanus. Expression of the previously published transcriptome-derived sequences was confirmed by RT-PCR of brain and eyestalk ganglia cDNAs; mass spectral analyses confirmed the presence of all six of the predicted GSEFLamide isoforms, IGSEFLamide, MGSEFLamide, AMGSEFLamide, VMGSEFLamide, ALGSEFLamide, and AVGSEFLamide, in Homarus brain extracts. AMGSEFLamide, of which there are multiple copies in the cloned transcripts, was the most abundant isoform detected in the brain. Because the GSEFLamides are present in the lobster nervous system, we hypothesized that they might function as neuromodulators, as is common for neuropeptides. We thus asked whether AMGSEFLamide modulates the rhythmic outputs of the cardiac ganglion and the stomatogastric ganglion. Physiological recordings showed that AMGSEFLamide potently modulates the motor patterns produced by both ganglia, suggesting that the GSEFLamides may serve as important and conserved modulators of rhythmic motor activity in arthropods.
      PubDate: 2018-11-21T01:43:28-08:00
      DOI: 10.1242/jeb.194092
  • The function of the ophiuroid nerve ring: how a decentralized nervous
           system controls coordinated locomotion [RESEARCH ARTICLE]
    • Authors: Clark, E. G; Kanauchi, D, Kano, T, Aonuma, H, Briggs, D. E. G, Ishiguro, A.
      Abstract: Elizabeth G. Clark, Daichi Kanauchi, Takeshi Kano, Hitoshi Aonuma, Derek E. G. Briggs, and Akio Ishiguro

      Echinoderms lack a centralized nervous control system yet each extant echinoderm class has evolved unique and effective strategies for locomotion. Brittle stars (Ophiuroidea) stride swiftly over the seafloor by coordinating motions of their five muscular arms. Their arms consist of many repeating segments, requiring them to use a complex control system to coordinate motions among segments and between arms. We conducted in vivo experiments with brittle stars to analyze the functional role of the nerve ring, which connects the nerves in each arm. These experiments were designed to determine how the ophiuroid nervous system performs complex decision-making and locomotory actions under decentralized control. Our results show that brittle star arms must be connected by the nerve ring for coordinated locomotion, but information can travel bidirectionally around the nerve ring so that it circumvents the severance. Evidence presented indicates that ophiuroids rely on adjacent nerve ring connections for sustained periodic movements. The number of arms connected via the nerve ring is correlated positively with the likelihood that the animal will show coordinated locomotion, indicating that integrated nerve ring tissue is critical for control. The results of the experiments should provide a basis for the advancement of complex artificial decentralized systems.
      PubDate: 2018-11-21T01:43:28-08:00
      DOI: 10.1242/jeb.192104
  • Caught red-handed: behaviour of brood thieves in an Indian ant [RESEARCH
    • Authors: Paul, B; Annagiri, S.
      Abstract: Bishwarup Paul and Sumana Annagiri

      Theft of resources is ubiquitous in the animal kingdom. An evolutionary arms race between thieves and their victims is expected. Though several studies have documented inter- and intraspecific theft of resources in different taxa, studies that delve into the behaviour of thieves and the factors that influence their behaviour have not been undertaken. In the current study on primitively eusocial ant Diacamma indicum we caught brood thieves red-handed, i.e. we observed them in the act of stealing brood and examined their behaviour. Thieves were persistent in their attempts though they faced aggression in the victim colony. Receiving aggression or failure to steal in the previous attempt negatively impacted thieves’ drive to reattempt. Successful thieves exited from victim nests about three times faster than others who were procuring brood from unguarded nests to avoid the risks associated with theft. On examining the factors that caused thieves to increase their exit speed using a series of experiments, we found that indirect cues of foreign colonies presence like odour or mere presence of foreign ants did not induce these changes in thieves. Thus we conclude that these ant thieves only respond to the direct threat posed by aggressive foreign ants. In this comprehensive study using behavioural experiments we reveal the simple rules of engagement between victims and brood thieves. Keywords: Diacamma indicum, Primitively eusocial, Ponerinae, Intraspecific stealing,
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.193755
  • Identification of novel circadian transcripts in the zebrafish retina
    • Authors: Ramasamy, S; Sharma, S, Iyengar, B. R, Vellarikkal, S. K, Sivasubbu, S, Maiti, S, Pillai, B.
      Abstract: Soundhar Ramasamy, Surbhi Sharma, Bharat Ravi Iyengar, Shamsudheen Karuthedath Vellarikkal, Sridhar Sivasubbu, Souvik Maiti, and Beena Pillai

      High fecundity, transparent embryos for monitoring the rapid development of organs and the availability of a well-annotated genome has made zebrafish a model organism of choice for developmental biology and neurobiology. This vertebrate model, a favourite in chronobiology studies, shows striking circadian rhythmicity in behaviour. Here, we identify novel genes in the zebrafish genome, which are expressed in the zebrafish retina. We further resolve the expression pattern over time and tentatively assign specific novel transcripts to retinal bipolar cells of the inner nuclear layer. Using chemical ablation and free run experiments we segregate the transcripts that are rhythmic when entrained by light from those that show sustained oscillations in the absence of external cues. The transcripts reported here with rigorous annotation and specific functions in circadian biology provide the groundwork for functional characterisation of novel players in the zebrafish retinal clock.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.192195
  • Effectiveness and efficiency of two distinct mechanisms for take-off in a
           derbid planthopper insect [RESEARCH ARTICLE]
    • Authors: Burrows, M; Ghosh, A, Yeshwanth, H. M, Dorosenko, M, Sane, S. P.
      Abstract: M. Burrows, A. Ghosh, H. M. Yeshwanth, M. Dorosenko, and S. P. Sane

      Analysis of the kinematics of take-off in the planthopper Proutista moesta (Hemiptera, Fulgoroidea, family Derbidae) from high speed videos showed that individual insects used two distinct mechanisms involving different appendages. The first was a fast take-off (55.7% of 106 take-offs by 11 insects) propelled by a synchronised movement of the two hind legs and without participation of the wings. The body was accelerated in 1 ms or less to a mean take-off velocity of 1.7 m s–1 while experiencing average forces of more than 150 times gravity. The power required from the leg muscles implicated a power-amplification mechanism. Such take-offs propelled the insect along its trajectory a mean distance of 7.9 mm in the first 5 ms after take-off. The second and slower take-off mechanism (44.3% of take-offs) was powered by beating movements of the wings alone with no discernible contribution from the hind legs. The resulting mean acceleration time was 16 times slower at 17.3 ms, the mean final velocity was six times lower at 0.27 m s–1, the g forces experienced were 80 times lower and the distance moved in 5 ms after take-off was 7 times shorter. The power requirements could be readily met by direct muscle contraction. The results suggest a testable hypothesis that the two mechanisms serve distinct behavioural actions; the fast take-offs could enable escape from predators; the slow take-offs that exert much lower ground reaction forces could enable take-off from more flexible substrates while also displacing the insect in a slower and more controllable trajectory.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.191494
  • Determinants of optimal leg use strategy: horizontal to vertical
           transition in the parkour wall climb [RESEARCH ARTICLE]
    • Authors: Croft, J. L; Schroeder, R. T, Bertram, J. E. A.
      Abstract: James L. Croft, Ryan T. Schroeder, and John E. A. Bertram

      This study examined the mechanics of the horizontal to vertical transition used by parkour athletes in wall climbing. The study serves as an alternative assessment of leg control strategy for a task related to normal running, but where the functional options differ substantially, so can expose the movement control priorities required to successfully complete the task. Ground reaction forces were measured in several expert parkour athletes and centre of mass trajectory was calculated from force plates embedded in the ground and the wall. Empirical measures were compared with movements predicted by a work-based control optimization model. The model captured the fundamental dynamics of the transition, so allowed an exploration of parameter sensitivity for success at the maneuver (run-up speed, foot placement, etc.). The optimal transition of both the model and the parkour athletes used a common intermediate run-up speed and appears determined largely by a trade-off of positive and negative leg work that accomplishes the task with minimum overall work.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.190983
  • Lateral line sensitivity in free swimming toadfish, Opsanus tau [RESEARCH
    • Authors: Mensinger, A. F; Van Wert, J. C, Rogers, L. S.
      Abstract: Allen F. Mensinger, Jacey C. Van Wert, and Loranzie S. Rogers

      A longstanding question in aquatic animal sensory physiology is the impact of self-generated movement on lateral line sensitivity. One hypothesis is that efferent modulation of the sensory hair cells cancels self-generated noise and allows fish to sample their surroundings while swimming. In the current experiments, microwire electrodes were chronically implanted into the anterior lateral line nerve of oyster toadfish and neural activity was monitored during forward movement. Fish were allowed to freely swim or were moved by a tethered sled. In all cases, neural activity increased during movement with no evidence of efferent modulation. The anterior lateral line of moving fish responded to a vibrating sphere or the tail oscillations of a robotic fish, indicating that the lateral line also remains sensitive to outside stimulus during self-generated movement. The results suggest that during normal swim speeds, lateral line neuromasts are not saturated and retain the ability to detect external stimuli without efferent modulation.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.190587
  • Object features and T4/T5 motion detectors modulate the dynamics of bar
           tracking by Drosophila [RESEARCH ARTICLE]
    • Authors: Keles, M. F; Mongeau, J.-M, Frye, M. A.
      Abstract: Mehmet F. Keles, Jean-Michel Mongeau, and Mark A. Frye

      Visual objects can be discriminated by static spatial features such as luminance or dynamic features such as relative movement. Flies track a solid dark vertical bar moving on a bright background, a behavioral reaction so strong that for a rigidly tethered fly, the steering trajectory is phase advanced relative to the moving bar, apparently in anticipation of its future position. By contrast, flickering bars that generate no coherent motion, or whose surface texture moves in the direction opposite to the bar generate steering responses that lag behind the stimulus. It remains unclear how the spatial properties of a bar influence behavioral response dynamics. We show that a dark bar defined by its luminance contrast to the uniform background drives a co-directional steering response that is phase-advanced relative to the response to a textured bar defined only by its motion relative to a stationary textured background. The textured bar drives an initial contra-directional turn and phase-locked tracking. The qualitatively distinct response dynamics could indicate parallel visual processing of a luminance versus motion-defined object. Calcium imaging shows that T4/T5 motion detecting neurons are more responsive to a solid dark bar than a motion defined bar. Genetically blocking T4/T5 neurons eliminates the phase-advanced co-directional response to the luminance-defined bar, leaving the orientation response largely intact. We conclude that T4/T5 neurons mediate a co-directional optomotor response to a luminance defined bar, thereby driving phase-advanced wing kinematics, whereas separate unknown visual pathways elicit the contra-directional orientation response.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.190017
  • Changes of gene expression but not cytosine methylation are associated
           with male parental care reflecting behavioural state, social context, and
           individual flexibility [RESEARCH ARTICLE]
    • Authors: Cunningham, C. B; Ji, L, McKinney, E. C, Benowitz, K. M, Schmitz, R. J, Moore, A. J.
      Abstract: C. B. Cunningham, L. Ji, E. C. McKinney, K. M. Benowitz, R. J. Schmitz, and A. J. Moore

      Behaviour is often on the front line response to changing environments. Recent studies show behavioural changes are associated with changes of gene expression; however, these studies have primarily focused on discrete behavioural states. We build on these studies by addressing additional contexts that produce qualitatively similar behavioural changes. We measured levels of gene expression and cytosine methylation, which is hypothesized to regulate the transcriptional architecture of behavioural transitions, within the brain during male parental care of the burying beetle Nicrophorus vespilloides in a factorial design. Male parenting is a suitably plastic behaviour because while male N. vespilloides typically do not provide direct care (i.e., feed offspring) when females are present, levels of feeding by a male equivalent to the female can be induced by removing the female. We examined three different factors: behavioural state (caring vs non-caring), different social contexts (with or without a female mate), and individual flexibility (if a male switched to direct care after his mate was removed). The greatest number of differentially expressed genes were associated with behavioural state, followed by social contexts, and lastly by individual flexibility. Cytosine methylation was not associated with changes of gene expression in any of the conditions. Our results suggest a hierarchical association between gene expression and the different factors, but that this process is not controlled by cytosine methylation. Our results further suggest that the extent a behaviour is transient plays an underappreciated role in determining its underpinning molecular mechanisms.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.188649
  • Encoding lateralization of jump kinematics and eye use in a locust via
           bio-robotic artifacts [RESEARCH ARTICLE]
    • Authors: Romano, D; Benelli, G, Stefanini, C.
      Abstract: Donato Romano, Giovanni Benelli, and Cesare Stefanini

      The effect of earlier exposure to lateral sensory stimuli in shaping the response to subsequent symmetric stimuli represents an important overlooked issue in neuroethology, with special reference to arthropods. In this research, we investigated the hypothesis to "program" jumping escape direction as well as surveillance orientation, in young and adult individuals of Locusta migratoria, as an adaptive consequence of prior exposure to directional-biased predator approaches generated by a robotic leopard gecko, Eublepharis macularius. The manipulation of the jumping escape direction was successfully achieved in young locusts, although young L. migratoria did not exhibit innately lateralized jumping escapes. Jumping escape direction was successfully manipulated also in adult locusts exhibiting innate lateralized jumping escape at individual level. The innate lateralization of each instar of L. migratoria in using a preferential eye during surveillance was not affected by prior lateralized exposure to the robotic gecko. Our results indicate a high plasticity of those escape motor outputs, that are occurring almost in real time with the perceived stimuli, making them greatly adaptable and compliant to environmental changes, to be effective and reliable. In addition, surveillance lateralization innately occurs at population-level in each instar of L. migratoria. Therefore, its low forgeability by environmental factors would avoid disorganization at swarm level and improving swarm coordination during group tasks. These findings are consistent with the fact that, as in vertebrates, in insects the right hemisphere is specialized in controlling fear and escape functions.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.187427
  • Developmental carry over effects of ocean warming and acidification in
           corals from a potential climate refugium, Gulf of Aqaba [RESEARCH ARTICLE]
    • Authors: Bellworthy, J; Menoud, M, Krueger, T, Meibom, A, Fine, M.
      Abstract: Jessica Bellworthy, Malika Menoud, Thomas Krueger, Anders Meibom, and Maoz Fine

      Coral reefs are degrading from the effects of anthropogenic activities including climate change. Under this stress, their ability to survive depends upon existing phenotypic plasticity, but also transgenerational adaptation. Parental effects are ubiquitous in nature, yet empirical studies of these effects in corals are scarce, particularly in the context of climate change. This study exposed mature colonies of the common reef building coral Stylophora pistillata from the Gulf of Aqaba to seawater conditions likely to occur just beyond the end of this century during the peak planulae brooding season (Representative Concentration Pathway 8.5: pH –0.4 and +5°C beyond present day). Parent and planulae physiology were assessed at multiple time-points during the experimental incubation. After five weeks incubation, parent colony's physiology exhibited limited treatment-induced changes. All significant time-dependent changes in physiology occurred in both ambient and treatment conditions. Planulae were also resistant to future ocean conditions with protein content, symbiont density, photochemistry, survival, and settlement success not significantly different compared to ambient conditions. High variability in offspring physiology was independent of parental or offspring treatments and indicate the use of bet-hedging strategy in this population. This study thus demonstrates weak climate change associated carry over effects. Furthermore, planulae display temperature and pH resistance similar to adult colonies and therefore do not represent a larger future population size bottleneck. The findings add support to the emerging hypothesis that the Gulf of Aqaba may serve as a climate change coral refugium aided by these corals’ inherent broad physiological resistance.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.186940
  • A gyroscopic advantage: phylogenetic patterns of compensatory movements in
           frogs [RESEARCH ARTICLE]
    • Authors: Frydlova, P; Sedlackova, K, Zampachova, B, Kurali, A, Hybl, J, Skoda, D, Kutilek, P, Landova, E, Cerny, R, Frynta, D.
      Abstract: Petra Frydlova, Kristyna Sedlackova, Barbora Zampachova, Aniko Kurali, Jan Hybl, David Skoda, Patrik Kutilek, Eva Landova, Rudolf Cerny, and Daniel Frynta

      Head and eye compensatory movements known as vestibulo-ocular and vestibulo-cervical reflexes are essential to stay orientated in space while moving. We have used a previously developed methodology focused on the detailed mathematical description of head compensatory movements in frogs without the need for any surgical procedures on the examined specimens. Our comparative study comprising 35 species of frogs from different phylogenetic background revealed species specific head compensatory abilities ensuring gaze stabilization. Moreover, we found a strong phylogenetical signal highlighting the great ability of compensatory head movements in families of Pyxicephalidae and Rhacophoridae from Natatanura group. On the other hand, families of Dendrobatidae and Microhylidae exhibited only poor or no head compensatory movements. Contrary to our expectation, the results did not corroborate an ecomorphological hypothesis anticipating a close relationship between ecological parameters and the head compensatory movements. We did not find any positive association between a more complex (3D structured, arboreal or aquatic) habitats as well as more saltatory behaviour and elevated abilities of head compensatory movements. Moreover, we found compensatory movements in most basal Archeobatrachia giving an indication of common ancestry of these abilities in frogs but variously pronounced in particular families. We hypothesize that the uncovered proper gaze stabilization during locomotion provided by the higher head compensatory abilities can improve or even enable visual perception of the prey. We interpret this completely novel finding as a possible gyroscopic advantage in a foraging context. We discuss putative consequences of such advanced neuromotor skills for diversification and ecological success of Natatanura group.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.186544
  • Phenotypic flexibility in respiratory traits is associated with improved
           aerial respiration in an amphibious fish out of water [RESEARCH ARTICLE]
    • Authors: Blanchard, T. S; Whitehead, A, Dong, Y. W, Wright, P. A.
      Abstract: T. S. Blanchard, A. Whitehead, Y. W. Dong, and P. A. Wright

      Amphibious fishes have evolved multiple adaptive strategies for respiring out of water, but there has been less focus on reversible plasticity. We tested the hypothesis that when amphibious fishes leave water, enhanced respiratory performance on land is the result of rapid functional phenotypic flexibility of respiratory traits. We acclimated four isogenic strains of Kryptolebias marmoratus to air for 0, 1, 3 or 7 days. We compared respiratory performance out of water with traits linked to the O2 cascade. Aerial O2 consumption rate was measured over a step-wise decrease in O2 levels. There were significant differences between strains, but time out of water had the largest impact on measured parameters. K. marmoratus had improved respiratory performance (lower aerial critical oxygen tension (Pcrit), higher regulation index (RI)) after only 1 day of air exposure and these changes were strongly associated with the change in hematocrit and dorsal cutaneous angiogenesis. Additionally, we found that 1-hour of air exposure induced the expression of four angiogenesis-associated genes, vegfa, angpt2, pecam-1 and efna1 in the skin. After 7 days in air, respiratory traits were not significantly linked to the variation in either aerial Pcrit or RI. Overall, our data indicate that there are two phases involved in the enhancement of aerial respiration; an initial rapid response (1 day) and a delayed response (7 days). We found evidence for the hypothesis that respiratory performance on land in amphibious fishes is the result of rapid flexibility in both O2 uptake and O2 carrying capacity.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.186486
  • Wing morphology, flight type and migration distance predict accumulated
           fuel load in birds [RESEARCH ARTICLE]
    • Authors: Vincze, O; Vagasi, C. I, Pap, P. L, Palmer, C, Moller, A. P.
      Abstract: Orsolya Vincze, Csongor I. Vagasi, Peter Laszlo Pap, Colin Palmer, and Anders Pape Moller

      Birds often accumulate large fat and protein reserves to fuel long-distance flights. While it is well known that species that fly the longest accumulate the largest amounts of fuel, considerable cross-species variation in fuel load is seen after controlling for overall migration distance. It remains unclear whether this variation can be explained by aerodynamic attributes of different species, despite obvious ecological and conservation implications. Here we collected data on wing morphology, flight type, migration distance and fuel load from 213 European bird species and explored three questions: (1) Does maximum fuel load relate to migration distance across species'; (2) Does wing morphology, as described by wing aspect ratio and wing loading, influence maximum fuel load, and; (3) Does flight type influence maximum fuel load' Our results indicate that maximum fuel load increases with migration across species, but residual variance is high. Our results indicate that maximum fuel load is also correlated with migration distance, but again residual variance is high. The latter variance is explained by aspect ratio and flight type, while wing loading and body mass explain little variance. Birds with slender wings accumulate less fuel than species with low wing aspect ratio when covering a similar migration distance. Continuously flapping species accumulate the largest amounts of fuel, followed by flapping and soaring, flapping and gliding species, while the smallest fuel loads were observed in birds with passerine-type flight. These results highlight complex eco-evolutionary adaptations to migratory behaviour, pointing toward the importance of energy-minimisation.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.183517
  • Age related responses to injury and repair in insect cuticle [RESEARCH
    • Authors: O'Neill, M; DeLandro, D, Taylor, D.
      Abstract: M. O'Neill, D. DeLandro, and D. Taylor

      The ability of female adult desert locusts (Schistocerca Gregaria) to repair injuries to their exoskeletons and restore mechanical strength over the course of their natural life was evaluated. It was discovered that younger insects are more capable of repairing injuries, displaying no significant decreases in failure strength, stiffness or bending moment to failure after 3 weeks of repair. Older insects in contrast were only capable of repairing to 70% of their original strength. Both older and younger insects carry out targeted deposition to repair injuries. Different mechanisms of failure were also examined and it was discovered that the cuticle of older insects is more susceptible to crack growth due to a large decrease in fracture toughness with age, making them more sensitive to scalpel cuts and punctures. The biological mechanisms that drive these changes are still under investigation.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.182253
  • Cyclic nature of the REM sleep-like state in the cuttlefish Sepia
           officinalis [RESEARCH ARTICLE]
    • Authors: Iglesias, T. L; Boal, J. G, Frank, M. G, Zeil, J, Hanlon, R. T.
      Abstract: Teresa L. Iglesias, Jean G. Boal, Marcos G. Frank, Jochen Zeil, and Roger T. Hanlon

      Sleep is a state of immobility characterized by three key criteria: an increased threshold of arousal, rapid reversal to an alert state, and evidence of homeostatic "rebound sleep" in which there is an increase of time spent in this quiescent state following sleep deprivation. Common European cuttlefish, Sepia officinalis, show states of quiescence during which they meet the last two of these three criteria, yet also show spontaneous bursts of arm and eye movements that accompany rapid changes in chromatophore patterns in the skin. Here we report that this rapid-eye movement sleep-like (REMS-like) state is cyclic in nature. Iterations of the REMS-like state last 2.42±0.22 min (±SE) and alternate with 34.01±1.49 min of the quiescent sleep-like state. These states alternate for durations lasting 176.89±36.71 min. We found clear evidence that this REMS-like state (i) occurs in animals younger than previously reported; (ii) follows an ultradian pattern; (iii) includes intermittent dynamic chromatophore patterning, representing fragments of normal patterning seen in the waking state for a wide range of signaling and camouflage; and (iv) shows variability in the intensity of expression of these skin patterns between and within individuals. These data suggest that cephalopods, which are molluscs with an elaborate brain and complex behavior, possess a sleep-like state that resembles behaviorally the vertebrate REM sleep state, although the exact nature and mechanism of this form of sleep may differ from that of vertebrates.
      PubDate: 2018-11-16T04:08:22-08:00
      DOI: 10.1242/jeb.174862
  • Deletion of a specific exon in the voltage-gated calcium channel,
           cacophony, causes disrupted locomotion in Drosophila larvae [RESEARCH
    • Authors: Lembke, K. M; Law, A. D, Ahrar, J, Morton, D. B.
      Abstract: Kayly M. Lembke, Alexander D. Law, Jasmine Ahrar, and David B. Morton

      Tar DNA binding protein 43 (TDP-43) is an RNA binding protein that regulates transcription, translation, and alternative splicing of mRNA. We have shown previously that null mutations of the Drosophila orthologue, Tar DNA-binding homologue (tbph), causes severe locomotion defects in larvae that are mediated by a reduction in the expression of the type II voltage-gated calcium channel, cacophony (cac). We also showed that TDP-43 regulates the inclusion of alternatively spliced exons of cacophony; tbph mutants showed significantly increased expression of cacophony isoforms lacking exon 7, a particularly notable finding as only one out of the 15 predicted isoforms lacks exon 7. To investigate the function of exon 7, we generated Drosophila mutant lines with a deletion that eliminates exon 7. This deletion phenocopies many defects in tbph mutants: a reduction in cacophony protein expression, locomotion defects in male and female third instar larvae, disrupted larval motor output, and also reduced activity levels in adult male flies. All these defects were rescued by expression of cacophony transcripts containing exon 7. By contrast, expression of a cacophony cDNA lacking exon 7 resulted in reduced cacophony protein levels and failed to rescue larval locomotion.
      PubDate: 2018-11-05T01:29:04-08:00
      DOI: 10.1242/jeb.191106
  • The role of parasitism in the energy management of a free-ranging bird
    • Authors: Hicks, O; Burthe, S. J, Daunt, F, Newell, M, Chastel, O, Parenteau, C, Green, J. A.
      Abstract: Olivia Hicks, Sarah J. Burthe, Francis Daunt, Mark Newell, Olivier Chastel, Charline Parenteau, and Jonathan A. Green

      Parasites often prompt sub-lethal costs to the host by eliciting immune responses. These costs can be hard to quantify but are crucial to our understanding of their host's ecology. Energy is a fundamental currency to quantify these costs, as energetic trade-offs often exist between key fitness-related processes. Daily energy expenditure (DEE) comprises of resting metabolic rate (RMR) and energy available for activity which are linked via the energy management strategy of an organism. Parasitism may play a role in the balance between self-maintenance and activity, as immune costs can be expressed in elevated RMR. Therefore, understanding energy use in the presence of parasitism enables mechanistic elucidation of potential parasite costs. Using a gradient of natural parasite load and proxies for RMR and DEE in a wild population of breeding European shags (Phalacrocorax aristotelis), we tested the effect of parasitism on maintenance costs as well as the relationship between proxies for RMR and DEE. We found a positive relationship between parasite load and our RMR proxy in females but not males and no relationship between proxies for RMR and DEE. This provides evidence for increased maintenance costs in individuals with higher parasite loads and suggests the use of an allocation energy management strategy, whereby an increase to RMR creates restrictions on energy allocation to other activities. This is likely to have fitness consequences as energy allocated to immunity is traded-off against reproduction. Our findings demonstrate that understanding energy management strategies alongside fitness drivers is central to understanding the mechanisms by which these drivers influence individual fitness.
      PubDate: 2018-11-05T01:29:04-08:00
      DOI: 10.1242/jeb.190066
  • Transforming growth factor-beta 1 (TGF-{beta}1) induces the
           differentiation of rainbow trout (Oncorhynchus mykiss) cardiac fibroblasts
           into myofibroblasts [RESEARCH ARTICLE]
    • Authors: Johnston, E. F; Gillis, T. E.
      Abstract: Elizabeth F. Johnston and Todd E. Gillis

      The collagen content of the rainbow trout heart increases in response to cold acclimation, and decreases with warm acclimation. This ability to remodel the myocardial extracellular matrix (ECM) makes these fish useful models to study the cellular pathways involved in collagen regulation in the vertebrate heart. Remodeling of the ECM in the mammalian heart is regulated, in part, by myofibroblasts which arise from pre-existing fibroblasts in response to transforming growth factor-beta 1 (TGF-β1). We have previously demonstrated that treatment of cultured rainbow trout cardiac fibroblasts with human TGF-β1 causes an increase in collagen production. Here we show that repetitive treatment of rainbow trout cardiac fibroblasts with a physiologically relevant concentration of human recombinant TGF-β1 results in a ~29-fold increase in phosphorylated small mothers against decapentaplegic 2 (pSmad2); a 2.9-fold increase in vinculin protein, a 1.2-fold increase in cellular size and a 3-fold increase in filamentous actin (F-actin). These are common markers of the transition of fibroblasts to myofibroblasts. Cells treated with TGF-β1 also had highly organized cytoskeletal alpha-smooth muscle actin, as well as increased transcript abundances of mmp-9, timp-2, and col1a1. Furthermore, using gelatin zymography, we demonstrate that TGF-β1 treatment causes a 5.3-fold increase in gelatinase activity. Together, these results demonstrate that trout cardiac fibroblasts have the capacity to differentiate into myofibroblasts and that this cell type can increase extracellular collagen turnover via gelatinase activity. Cardiac myofibroblasts are, therefore, likely involved in the remodeling of the cardiac ECM in the trout heart during thermal acclimation.
      PubDate: 2018-11-05T01:29:04-08:00
      DOI: 10.1242/jeb.189167
  • Periodic, moderate water flow reversibly increases hair bundle density and
           size in Nematostella vectensis [RESEARCH ARTICLE]
    • Authors: Campbell, A; Dykes, A, Mire, P.
      Abstract: Allison Campbell, Ashlyn Dykes, and Patricia Mire

      Animals employ hair bundles on hair cells to detect flow, vibrations, and gravity. Hair bundles on sea anemone tentacles detect nearby vibrations in the water column produced by prey movements and then regulate discharge of cnidae to capture prey. This study investigates (i): the progressive effects of periodic water flow on hair bundle morphology and density of hair bundles and cnidae in sea anemones, (ii): the reversibility of the flow response and (iii): the ability of the response to be expedited with increased flow duration. Linear density of hair bundles along tentacles and each hair bundle's dimensions was measured in anemones exposed to flow and in the absence of flow. With increasing days of flow, hair bundles in anemones exposed to flow for one hour every week day for twenty days increased in density and grew longer and wider at bases and middles whereas controls did not. Time courses fit to a linear function exhibited significantly larger positive slopes from animals exposed to flow compared to controls. Hair bundles in anemones exposed to flow for three hours each day increased in linear density, length, base-width and middle-width after ten days of flow and returned to control levels after ten days following cessation of flow. An apparent increase in density of cnidae with flow barely missed statistical significance. Therefore, anemone hair bundles are dynamically and reversibly modified by periodic, moderate flow to become more abundant and robust. These findings may have relevance to hair cells in acoustico-lateralis systems of higher animals.
      PubDate: 2018-11-05T01:29:04-08:00
      DOI: 10.1242/jeb.181081
  • Diapause-associated changes in the lipid and metabolite profile of the
           Asian tiger mosquito, Aedes albopictus [RESEARCH ARTICLE]
    • Authors: Batz, Z. A; Armbruster, P. A.
      Abstract: Zachary A. Batz and Peter A. Armbruster

      Diapause is an alternative life-history strategy that allows organisms to enter developmental arrest in anticipation of unfavorable conditions. Diapause is widespread among insects and plays a key role in enhancing overwinter survival as well as defining the seasonal and geographic distributions of populations. Next generation sequencing has greatly advanced our understanding of the transcriptional basis for this crucial adaptation but less is known about regulation of embryonic diapause physiology at the metabolite level. Here, we characterized the lipid and metabolite profile of embryonic diapause in the Asian tiger mosquito, Aedes albopictus. We used an untargeted approach to capture the relative abundance of 250 lipids and 241 metabolites. We observed adjustments associated with increased energy storage, including an accumulation of lipids, the formation of larger lipid droplets, and increased lipogenesis, as well as metabolite shifts suggesting reduced energy utilization. We also found changes in neuroregulatory- and insulin-associated metabolites with potential roles in diapause regulation. Finally, we detected a group of unidentified, diapause-specific metabolites which have similar physical properties steroids/steroid derivatives and may be associated with the ecdysteroidal regulation of embryonic diapause in Ae. albopictus. Together, these results deepen our understanding of the metabolic regulation of embryonic diapause and identify key targets for future investigations.
      PubDate: 2018-11-01T01:29:07-07:00
      DOI: 10.1242/jeb.189480
  • Underlying mechanisms and ecological context of variation in exploratory
           behavior of the Argentine ant, Linepithema humile [RESEARCH ARTICLE]
    • Authors: Page, H; Sweeney, A, Pilko, A, Pinter-Wollman, N.
      Abstract: Hannah Page, Andrew Sweeney, Anna Pilko, and Noa Pinter-Wollman

      Uncovering how and why animals explore their environment is fundamental for understanding population dynamics, the spread of invasive species, species interactions etc. In social animals, individuals within a group can vary in their exploratory behavior and the behavioral composition of the group can determine its collective success. Workers of the invasive Argentine ant (Linepithema humile) exhibit individual variation in exploratory behavior, which affects the colony's collective nest selection behavior. Here we examine the mechanisms underlying this behavioral variation in exploratory behavior and determine its implications for the ecology of this species. We first establish that individual variation in exploratory behavior is repeatable and consistent across situations. We then show a relationship between exploratory behavior and the expression of genes that have been previously linked with other behaviors in social insects. Specifically, we find a negative relationship between exploratory behavior and the expression of the foraging (Lhfor) gene. Finally, we determine how colonies allocate exploratory individuals in natural conditions. We find that ants from inside the nest are the least exploratory individuals, while workers on newly formed foraging trails are the most exploratory individuals. Furthermore, we found temporal differences throughout the year – in early-mid spring, when new resources emerge, workers are more exploratory than at the end of winter, potentially allowing the colony to find and exploit new resources. These findings reveal the importance of individual variation in behavior for the ecology of social animals.
      PubDate: 2018-11-01T01:29:07-07:00
      DOI: 10.1242/jeb.188722
  • Temperature and dehydration effects on metabolism, water uptake, and the
           partitioning between respiratory and cutaneous evaporative water loss in a
           terrestrial toad [RESEARCH ARTICLE]
    • Authors: Senzano, L. M; Andrade, D. V.
      Abstract: Luis Miguel Senzano and Denis Vieira Andrade

      Terrestrial anurans often experience fluctuations in body temperature and hydration state, which are known to influence evaporative water loss through the skin (EWLSkin) and lungs (EWLResp). These effects arises from associated changes in skin permeability, metabolism and lung ventilation. Herein, we determined the rates of EWLSkin and EWLResp in the terrestrial toad, Rhinella schneideri, at different temperatures and hydration states. We measured oxygen uptake rates to verify whether alterations in the partitioning between EWLSkin and EWLResp were associated to metabolic induced changes in pulmonary gas exchange. We also measured the influence of hydration and temperature on water uptake (WU) through the skin. Finally, since estimates of skin resistance to evaporation (Rs) are usually inferred from total evaporative water loss (EWLTotal), under the assumption of negligible EWLResp, we calculate the potential error in accepting this assumption, under different temperature and hydration states. EWLSkin and EWLResp increased with temperature, but this response was greater for EWLResp, which was attributed to the temperature-induced elevation in metabolism and lung ventilation. Dehydration caused a decrease in the relative contribution of EWLSkin to EWLTotal, mirrored by the concurrent increase in the contribution of EWLResp, at all temperatures. Thus, Rs increased with dehydration. WU rates were dictated by dehydration with little influence of temperature. The partitioning between EWLSkin and EWLResp was affected by both temperature and hydration state and, under some set of conditions, considering EWLResp as negligible led to significant errors in the assessment of skin resistance to evaporation.
      PubDate: 2018-11-01T01:29:07-07:00
      DOI: 10.1242/jeb.188482
  • Forelimb position affects facultative bipedal locomotion in lizards
    • Authors: Kinsey, C. T; McBrayer, L. D.
      Abstract: Chase T. Kinsey and Lance D. McBrayer

      Recent work indicates that bipedal posture in lizards is advantageous during obstacle negotiation (Parker and McBrayer, 2016). However, little is known about how bipedalism occurs beyond a lizard's acceleratory threshold. Furthermore, no study to date has examined the effects of forelimb position on the body center of mass in the context of bipedalism. This study quantified the frequency of bipedalism when sprinting with vs. without an obstacle at 0.8 meters from initiating a sprint. Forelimb positions were quantified during bipedal running at the start of a sprint and when crossing an obstacle. Two species with contrasting body forms (and thus different body center of mass; BCoM) were studied (Sceloporus woodi, Aspidoscelis sexlineata) to assess potential variation due to body plan and obstacle crossing behavior. No significant difference in frequency of bipedalism was observed in S. woodi with or without an obstacle. However, A. sexlineata primarily used a bipedal posture when sprinting. Forelimb positions were variable in S. woodi and stereotyped in A. sexlineata. Caudal extension of the forelimbs helped shift the BCoM posteriorly and transition to, or maintain, a bipedal posture in A. sexlineata, but not S. woodi. The posterior shift in BCoM, aided by more caudally placed forelimbs, helps raise the trunk from the ground, regardless of obstacle presence. The body plan, specifically the length of the trunk and tail, and forelimb position work together with acceleration to shift the BCoM posteriorly to transition to a bipedal posture. Thus, species exhibit morphological and behavioral adjustments to transition to and maintain facultative bipedalism while sprinting.
      PubDate: 2018-10-26T04:24:49-07:00
      DOI: 10.1242/jeb.185975
  • Diet and ambient temperature interact to shape plasma fatty acid
           composition, basal metabolic rate, and oxidative stress in great tits
    • Authors: Andersson, M. N; Nilsson, J, Nilsson, J.-A, Isaksson, C.
      Abstract: Martin N. Andersson, Johan Nilsson, Jan-Ake Nilsson, and Caroline Isaksson

      Diet and ambient temperature affect animal physiology, survival and reproductive success. However, knowledge of how these environmental factors interact to shape physiological processes and life-history traits of birds and other animals is largely lacking. By exposing adult great tits (Parus major) to two contrasting diets (saturated or unsaturated fatty acids; SFA and UFA, respectively) and ambient temperatures (3°C versus 20°C) that the birds encounter in nature, we investigated the effects of these two factors on several physiological parameters. Our results show that diet and ambient temperature interact to affect the composition of plasma fatty acids, basal metabolic rate (BMR), and oxidative stress, which are thought to affect the life-history and survival of individuals. Specifically, birds provided the SFA-rich diet had higher mass-specific BMR and oxidative stress (levels of lipid peroxidation) after exposure to low compared to high ambient temperature, whereas the opposite pattern was evident for the UFA-provided birds. Surprisingly, the SFA-provided birds had higher relative levels of monounsaturated fatty acids compared to the UFA-provided birds at low ambient temperature, whereas the opposite, and expected, pattern was found at the high temperature. Although the present study focuses on the physiological implications of the dietxtemperature interaction, our results might also be important for the leading theories of ageing, which currently do not take interactions between environmental factors into account. In addition, the present results are important for wildlife management due to anthropogenic feeding of wild animals across variable and changing climatic conditions.
      PubDate: 2018-10-25T00:36:40-07:00
      DOI: 10.1242/jeb.186759
  • Sleep regulates visual selective attention in Drosophila [RESEARCH
    • Authors: Kirszenblat, L; Ertekin, D, Goodsell, J, Zhou, Y, Shaw, P. J, van Swinderen, B.
      Abstract: Leonie Kirszenblat, Deniz Ertekin, Joseph Goodsell, Yanqiong Zhou, Paul J. Shaw, and Bruno van Swinderen

      Although sleep deprivation is known to impair attention in humans and other mammals, the underlying reasons are not well understood, and whether similar effects are present in non-mammalian species is not known. We therefore sought to investigate whether sleep is important for optimizing attention in an invertebrate species, the genetic model Drosophila melanogaster. We developed a high-throughput paradigm to measure visual attention in freely-walking Drosophila, using competing foreground/background visual stimuli. We found that whereas sleep-deprived flies could respond normally to either stimulus alone, they were more distracted by background cues in a visual competition task. Other stressful manipulations such as starvation, heat exposure, and mechanical stress had no effects on visual attention in this paradigm. In contrast to sleep deprivation, providing additional sleep using the GABA-A agonist 4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridine-3-ol (THIP) did not affect attention in wild-type flies, but specifically improved attention in the learning mutant dunce. Our results reveal a key function of sleep in optimizing attention processes in Drosophila, and establish a behavioral paradigm that can be used to explore the molecular mechanisms involved.
      PubDate: 2018-10-24T05:17:26-07:00
      DOI: 10.1242/jeb.191429
  • Rafting on floating fruit is effective for oceanic dispersal of flightless
           weevils [RESEARCH ARTICLE]
    • Authors: Yeh, H.-Y; Tseng, H.-Y, Lin, C.-P, Liao, C.-P, Hsu, J.-Y, Huang, W.-S.
      Abstract: Hui-Ying Yeh, Hui-Yun Tseng, Chung-Ping Lin, Chen-Pan Liao, Jung-Ya Hsu, and Wen-San Huang

      Terrestrial species, especially non-vagile ones (those unable to fly or swim), cannot cross oceans without exploiting other animals or floating objects. However, the colonisation history of flightless Pachyrhynchus weevils, inferred from genetic data, reveals their ability to travel long distances to colonise remote islands. Here, we used captive-bred P. jitanasaius to analyse (i) the physiological tolerance of weevils (egg, larva and adult stages) to different levels of salinity; (ii) the survival rate of larvae in a simulated ocean environment in the laboratory; and (iii) the survival rate of larvae in a field experiment in the ocean using fruit of the fish poison tree floating on the Kuroshio Current in the Pacific Ocean. We found that the survival rate of larvae in seawater was lower than in fresh water, although if the larvae survived 7 days of immersion in seawater, some emerged as adults in the subsequent rearing process. No adults survived for more than 2 days, regardless of salinity level. After floating separately for 6 days in salt water in the laboratory and in the Kuroshio Current, two of 18 larvae survived in the fruit. This study provides the first empirical evidence that P. jitanasaius larvae can survive ‘rafting’ on ocean currents and that the eggs and larvae of these weevils have the highest probability to cross the oceanic barrier. This ability may facilitate over-the-sea dispersal of these flightless insects and further shape their distribution and speciation pattern in the Western Pacific islands.
      PubDate: 2018-10-23T02:31:47-07:00
      DOI: 10.1242/jeb.190488
  • Measurement and modelling of primary sex ratios for species with
           temperature-dependent sex determination [RESEARCH ARTICLE]
    • Authors: Massey, M. D; Holt, S. M, Brooks, R. J, Rollinson, N.
      Abstract: Melanie D. Massey, Sarah M. Holt, Ronald J. Brooks, and Njal Rollinson

      For many oviparous animals, incubation temperature influences sex through temperature-dependent sex determination (TSD). Although climate change may skew sex ratios in species with TSD, few available methods predict sex under natural conditions, fewer still are based on mechanistic hypotheses of development, and field tests of existing methods are rare. We propose a new approach that calculates the probability of masculinization (PM) in natural nests. This approach subsumes the mechanistic hypotheses describing the outcome of TSD, by integrating embryonic development with the temperature-sex reaction norm. Further, we modify a commonly used method of sex ratio estimation, the Constant Temperature Equivalent (CTE), to provide quantitative estimates of sex ratios. We test our new approaches using snapping turtles (Chelydra serpentina). We experimentally manipulate nests in the field, and find that the PM method is better supported than the modified CTE, explaining 69% of the variation in sex ratios across 27 semi-natural nests. Next, we use the PM method to predict variation in sex ratios across 14 natural nests over two years, explaining 67% of the variation. We suggest that the PM approach is effective and broadly-applicable to species with TSD, particularly for forecasting how sex ratios may respond to climate change. Interestingly, we also found that the modified CTE explained up to 64% of variation in sex ratios in a Type II TSD species, suggesting our modifications will be useful for future research. Finally, our data suggest that the Algonquin Park population of snapping turtles possesses resilience to biased sex ratios under climate change.
      PubDate: 2018-10-23T02:31:47-07:00
      DOI: 10.1242/jeb.190215
  • Scaling of claw sharpness: mechanical constraints reduce attachment
           performance in larger insects [RESEARCH ARTICLE]
    • Authors: Pattrick, J. G; Labonte, D, Federle, W.
      Abstract: Jonathan G. Pattrick, David Labonte, and Walter Federle

      Claws are the most widespread attachment devices in animals, but comparatively little is known about the mechanics of claw attachment. A key morphological parameter in determining attachment ability is claw sharpness; however, there is a conflict between sharpness and fracture resistance. Sharper claws can interlock on more surfaces but are more likely to break. Body size interacts with this conflict such that larger animals should have much blunter claws and consequently poorer attachment ability than smaller animals. This expected size-induced reduction in attachment performance has not previously been investigated, and it is unclear how animals deal with this effect, and if it indeed exists. We explored the scaling of claw sharpness with body size using four insect species (Nauphoeta cinerea, Gromphadorhina portentosa, Atta cephalotes and Carausius morosus) each covering a large size range. The scaling of claw sharpness varied significantly between species, suggesting that they face different pressures regarding claw function. Attachment forces were measured for A. cephalotes and G. portentosa (which had different scaling of claw sharpness) on several rough surfaces using a centrifuge setup. As expected, attachment performance was poorer in larger animals. Firstly, larger animals were more likely to slip, though this effect depended on the scaling of claw sharpness. Secondly, when they gripped, they attached with smaller forces relative to their weight. This size-induced reduction in attachment performance has significant implications for the attachment ability of larger animals on rough surfaces.
      PubDate: 2018-10-23T02:31:46-07:00
      DOI: 10.1242/jeb.188391
  • Mechanical behavior of shark vertebral centra at biologically relevant
           strains [RESEARCH ARTICLE]
    • Authors: Ingle, D. I; Natanson, L. J, Porter, M. E.
      Abstract: D. I. Ingle, L. J. Natanson, and M. E. Porter

      Cartilaginous shark skeletons experience axial deformation at the intervertebral joints, but also within the mineralized cartilaginous centrum, which can compress to between 3 - 8% of its original length in a free-swimming shark. Previous studies have focused on shark centra mechanical properties when loaded to failure, and our goal was to determine properties when compressed to a biologically relevant strain. We selected vertebrae from six shark species and from the anterior and posterior regions of the vertebral column. Centra were x-radiographed to measure double cone proportion and apex angles, and were mechanically tested at three displacement rates to 4% strain. We determined the variation in toughness and stiffness of vertebral centra among shark species, ontogenetic stages, testing strain rates, and compared anterior and posterior regions of the vertebral column. Our results suggest that toughness and stiffness, which are positively correlated, may be operating in concert to support lateral body undulations, while providing efficient energy transmission and return in these swift-swimming apex predators. We analyzed the contribution of double cone proportion and apex angles to centra mechanical behavior. We found that the greatest stiffness and toughness were in the youngest sharks and from the posterior body, and there was significant interspecific variation. Significant inverse correlations were found between mechanical properties and double cone apex angles suggesting that properties can be partially attributed to the angle forming the double cone apex. These comparative data highlight the importance of understanding cartilaginous skeleton mechanics under wide variety of loading conditions representative of swimming behaviors seen in the wild.
      PubDate: 2018-10-23T02:31:46-07:00
      DOI: 10.1242/jeb.188318
  • Interactions between corticosterone phenotype, environmental stressor
           pervasiveness and irruptive movement-related survival [RESEARCH ARTICLE]
    • Authors: Jessop, T. S; Webb, J, Dempster, T, Feit, B, Letnic, M.
      Abstract: Tim S. Jessop, Jonathan Webb, Tim Dempster, Benjamin Feit, and Mike Letnic

      Animals use irruptive movement to avoid exposure to stochastic and pervasive environmental stressors that impact fitness. Beneficial irruptive movements transfer individuals from high-stress areas (conferring low fitness) to alternate localities that may improve survival or reproduction. However, being stochastic, environmental stressors can limit an animal's preparatory capacity to enhance irruptive movement performance. Thus individuals must rely on standing, or rapidly induced, physiological and behavioural responses. Rapid elevation of glucocorticoid hormones in response to environmental stressors are widely implicated in adjusting physiological and behaviour processes that could influence irruptive movement capacity. However, there remains little direct evidence to demonstrate that corticosterone regulated movement performance, nor the interaction with the pervasiveness of environmental stress, confers adaptive movement outcomes. Here we compared how movement-related survival of cane toads (Rhinella marina) varied with three different experimental corticosterone phenotypes across four increments of increasing environmental stressor pervasiveness (i.e. distance from water in a semi-arid landscape). Our results indicated that toads with phenotypically increased corticosterone levels attained higher movement-related survival compared to individuals with control or lowered corticosterone phenotypes. However, the effects of corticosterone phenotypes on movement-related survival to some extent co-varied with stressor pervasiveness. Thus our study demonstrates how the interplay among an individual's corticosterone phenotype and movement capacity alongside the arising costs of movement and the pervasiveness of the environmental stressor can affect survival outcomes.
      PubDate: 2018-10-23T02:31:46-07:00
      DOI: 10.1242/jeb.187930
  • Flight energetics, caste dimorphism and scaling properties in the
           bumblebee Bombus impatiens [RESEARCH ARTICLE]
    • Authors: Billardon, F; Darveau, C.-A.
      Abstract: Fannie Billardon and Charles-A. Darveau

      Animal size affects energetics of locomotion. Using female caste dimorphism in bumblebees, we assessed how body mass impacted morphological and physiological traits linked with flight. The allometric relationships obtained for workers wing surface area, wingbeat frequency, flight and resting metabolic rates could predict the trait values of queens that are more than four-fold larger. Flight success of queens decreased over time in part due to a large increase in body mass, and decrease in traits linked with flight, namely wingbeat frequency, metabolic rate, and the activity of metabolic enzymes tended to decrease. After taking into account temporal changes, body mass, flight wingbeat frequency and metabolic rate were repeatable. Finally, we found significant family resemblance for all traits measured, indicating that shared genes and/or environmental effects impact phenotypic variation. Together, we here show that the functional association between body morphology and flight physiology is robust, providing further insights into the mechanistic basis of metabolic rate scaling patterns during locomotion in animals.
      PubDate: 2018-10-23T02:31:46-07:00
      DOI: 10.1242/jeb.187807
  • Subspecies differences in thermal acclimation of mitochondrial function
           and the role of uncoupling proteins in killifish [RESEARCH ARTICLE]
    • Authors: Bryant, H. J; Chung, D. J, Schulte, P. M.
      Abstract: Heather J. Bryant, Dillon J. Chung, and Patricia M. Schulte

      Thermal effects on mitochondrial efficiency and ATP production can influence whole-animal thermal tolerance and performance. Thus, organisms may have the capacity to alter mitochondrial processes through acclimation or adaptation to mitigate these effects. One possible mechanism is through the action of uncoupling proteins (UCPs) which can decrease the proton motive force independent of the production of ATP. To test this hypothesis, we examined the mRNA expression patterns of UCP isoforms and characterized the effects of thermal acclimation and putative local thermal adaptation on mitochondrial capacity, proton leak, and P/O ratios in two subspecies of Atlantic killifish (Fundulus heteroclitus). Ucp1 was the dominant isoform in liver and was more highly expressed in northern killifish. We found that cold acclimation increased mitochondrial capacity (state III and maximum substrate oxidation capacity), state II membrane potential, proton leak, and P/O ratios in northern, but not southern killifish liver mitochondria. Palmitate-induced mitochondrial uncoupling was detected in northern, but not southern, killifish liver mitochondria, consistent with the differences in mRNA expression between the subspecies. Taken together, our data suggest that mitochondrial function is more plastic in response to thermal acclimation in northern killifish than southern killifish and that UCP1 may play a role in regulating the proton motive force in northern, but not southern killifish in response to thermal acclimation. These data demonstrate the potential for adaptive variation in mitochondrial plasticity in response to cold.
      PubDate: 2018-10-23T02:31:46-07:00
      DOI: 10.1242/jeb.186320
  • Altered thermoregulation as a driver of host behaviour in
           glochidia-parasitised fish [RESEARCH ARTICLE]
    • Authors: Horky, P; Slavik, O, Douda, K.
      Abstract: Pavel Horky, Ondrej Slavik, and Karel Douda

      Parasites alter their host behaviour and vice versa as a result of mutual adaptations in the evolutionary arms race. One of these adaptations involves changes in host thermoregulation, which has the potential to harm the parasite and thereby act as a defence mechanism. We used a model of the brown trout Salmo trutta experimentally parasitised with ectoparasitic larvae called glochidia from the endangered freshwater pearl mussel Margaritifera margaritifera to reveal whether parasitation alters fish behavioural thermoregulation. A study based on radio telemetry temperature sensors was performed during almost one year M. margaritifera parasitic stage. Glochidia infested S. trutta altered its thermoregulation through active searching for habitats with different thermal regimes. General preference for lower temperature of infested fish varied, being sometimes above, sometimes below the temperature preferred by uninfested individuals. Infested fish also preferred different temperatures across localities, while uninfested fish maintained their thermal preference no matter which stream they inhabited. Glochidia further induced the expression of a behavioural syndrome among S. trutta personality traits, suggesting that it might increase the probability that the fish host would occur in the glochidia temperature optimum. Our findings present the first evidence that thermoregulation plays a fundamental role in the relationship of affiliated mussels and their fish hosts. Incorporating thermoregulation issue in the study of this relationship can help to interpret results from previous behavioural studies as well as to optimise management measures related to endangered mussels.
      PubDate: 2018-10-23T02:31:46-07:00
      DOI: 10.1242/jeb.184903
  • Jet-paddling jellies: swimming performance in the Rhizostomeae jellyfish
           Catostylus mosaicus (Quoy and Gaimard, 1824) [RESEARCH ARTICLE]
    • Authors: Neil, T. R; Askew, G. N.
      Abstract: Thomas R. Neil and Graham N. Askew

      Jellyfish are a successful and diverse class of animals that swim via jet propulsion, with swimming performance and propulsive efficiency being related to the animal's feeding ecology and body morphology. The Rhizostomeae jellyfish lack tentacles but possess four oral lobes and eight trailing arms at the centre of their bell, giving them a body morphology quite unlike that of other free-swimming medusae. The implications of this body morphology on the mechanisms by which thrust is produced are unknown. Here we determined the wake structure and propulsive efficiency in the blue-blubber jellyfish Catostylus mosaicus; order Rhizostomeae). The animal is propelled during both bell contraction and bell relaxation by different thrust generating mechanisms. During bell contraction, a jet of fluid is expelled from the subumbrellar cavity, which results from the interaction between the counter-rotating stopping (from the preceding contraction cycle) and starting vortices, creating a vortex superstructure and propulsion. This species is also able to utilize passive energy recapture, that increases the animal's swimming velocity towards the end of the bell expansion phase when the bell diameter is constant. The thrust produced during this phase is the result of the flexible bell margin manoeuvring the stopping vortex into the subumbrellar cavity during bell relaxation, enhancing its circulation, and creating a region of high pressure on the inner surface of the bell and, consequently, thrust. These mechanisms of thrust generation result in C. mosaicus having a relatively high propulsive efficiency compared to other swimmers, indicating that economical locomotion could be a contributing factor in the ecological success of these medusan swimmers.
      PubDate: 2018-10-22T06:33:00-07:00
      DOI: 10.1242/jeb.191148
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