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BIOTECHNOLOGY (227 journals)                  1 2 | Last

Showing 1 - 200 of 227 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
Advances in Bioscience and Biotechnology     Open Access   (Followers: 15)
Advances in Genetic Engineering & Biotechnology     Hybrid Journal   (Followers: 8)
African Journal of Biotechnology     Open Access   (Followers: 6)
Algal Research     Partially Free   (Followers: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Bioinformatics Research     Open Access   (Followers: 8)
American Journal of Polymer Science     Open Access   (Followers: 30)
Animal Biotechnology     Hybrid Journal   (Followers: 10)
Annales des Sciences Agronomiques     Full-text available via subscription  
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 42)
Applied Bioenergy     Open Access  
Applied Biosafety     Hybrid Journal  
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 62)
Applied Mycology and Biotechnology     Full-text available via subscription   (Followers: 5)
Arthroplasty Today     Open Access   (Followers: 1)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 2)
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: 4)
Bio-Algorithms and Med-Systems     Hybrid Journal   (Followers: 1)
Bio-Research     Full-text available via subscription   (Followers: 2)
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  
Biofuels     Hybrid Journal   (Followers: 11)
Biofuels Engineering     Open Access   (Followers: 1)
Biological & Pharmaceutical Bulletin     Full-text available via subscription   (Followers: 5)
Biological Cybernetics     Hybrid Journal   (Followers: 10)
Biomarkers and Genomic Medicine     Open Access   (Followers: 5)
Biomarkers in Drug Development     Partially Free   (Followers: 1)
Biomaterials Research     Open Access   (Followers: 4)
BioMed Research International     Open Access   (Followers: 6)
Biomédica     Open Access  
Biomedical Engineering Research     Open Access   (Followers: 7)
Biomedical glasses     Open Access  
Biomedical Reports     Full-text available via subscription  
BioMedicine     Open Access  
Bioprinting     Hybrid Journal  
Bioresource Technology Reports     Hybrid Journal  
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 22)
Biosimilars     Open Access   (Followers: 1)
Biosurface and Biotribology     Open Access  
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
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: 7)
Biotechnology & Biotechnological Equipment     Open Access   (Followers: 5)
Biotechnology Advances     Hybrid Journal   (Followers: 33)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 160)
Biotechnology and Bioprocess Engineering     Hybrid Journal   (Followers: 6)
Biotechnology and Genetic Engineering Reviews     Hybrid Journal   (Followers: 14)
Biotechnology and Health Sciences     Open Access   (Followers: 1)
Biotechnology and Molecular Biology Reviews     Open Access   (Followers: 1)
Biotechnology Annual Review     Full-text available via subscription   (Followers: 7)
Biotechnology for Biofuels     Open Access   (Followers: 11)
Biotechnology Frontier     Open Access   (Followers: 2)
Biotechnology Journal     Hybrid Journal   (Followers: 16)
Biotechnology Law Report     Hybrid Journal   (Followers: 4)
Biotechnology Letters     Hybrid Journal   (Followers: 34)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Biotechnology Reports     Open Access  
Biotechnology Research International     Open Access   (Followers: 2)
Biotechnology Techniques     Hybrid Journal   (Followers: 10)
Biotecnología Aplicada     Open Access  
Biotribology     Hybrid Journal  
BMC Biotechnology     Open Access   (Followers: 16)
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)
Contributions to Tobacco Research     Open Access   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biotechnology     Hybrid Journal   (Followers: 20)
Crop Breeding and Applied Biotechnology     Open Access   (Followers: 4)
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: 14)
Current trends in Biotechnology and Pharmacy     Open Access   (Followers: 9)
EBioMedicine     Open Access  
Electronic Journal of Biotechnology     Open Access   (Followers: 1)
Entomologia Generalis     Full-text available via subscription  
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: 13)
Food Science and Biotechnology     Hybrid Journal   (Followers: 9)
Frontiers in Bioengineering and Biotechnology     Open Access   (Followers: 6)
Frontiers in Systems Biology     Open Access   (Followers: 2)
Fungal Biology and Biotechnology     Open Access   (Followers: 1)
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  
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)
IIOAB Letters     Open Access  
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: 1)
Indonesian Journal of Biotechnology     Open Access   (Followers: 1)
Industrial Biotechnology     Hybrid Journal   (Followers: 18)
International Biomechanics     Open Access  
International Journal of Bioinformatics Research and Applications     Hybrid Journal   (Followers: 15)
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: 2)
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)
Journal of Biometrics & Biostatistics     Open Access   (Followers: 3)
Journal of Bioterrorism & Biodefense     Open Access   (Followers: 6)
Journal of Petroleum & Environmental Biotechnology     Open Access   (Followers: 2)
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: 6)
Journal of Applied Biomedicine     Open Access   (Followers: 3)
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 Biosecurity, Biosafety and Biodefense Law     Hybrid Journal   (Followers: 3)
Journal of Biotechnology     Hybrid Journal   (Followers: 68)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chitin and Chitosan Science     Full-text available via subscription  
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: 7)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 3)
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: 16)
Journal of Integrative Bioinformatics     Open Access  
Journal of International Biotechnology Law     Hybrid Journal   (Followers: 3)
Journal of Medical Imaging and Health Informatics     Full-text available via subscription  
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 14)
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: 2)
Journal of Organic and Biomolecular Simulations     Open Access  
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 6)
Journal of Science and Applications : Biomedicine     Open Access  
Journal of the Mechanical Behavior of Biomedical Materials     Hybrid Journal   (Followers: 11)
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: 5)
Messenger     Full-text available via subscription  
Metabolic Engineering Communications     Open Access   (Followers: 4)
Metalloproteinases In Medicine     Open Access  
Microalgae Biotechnology     Open Access   (Followers: 2)
Microbial Biotechnology     Open Access   (Followers: 9)
MicroMedicine     Open Access   (Followers: 3)
Molecular and Cellular Biomedical Sciences     Open Access  
Molecular Biotechnology     Hybrid Journal   (Followers: 16)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Nanobiomedicine     Open Access  
Nanobiotechnology     Hybrid Journal   (Followers: 3)
Nanomaterials and Nanotechnology     Open Access  
Nanomaterials and Tissue Regeneration     Open Access  
Nanomedicine and Nanobiology     Full-text available via subscription  
Nanomedicine Research Journal     Open Access  
Nanotechnology Reviews     Hybrid Journal   (Followers: 5)
Nature Biotechnology     Full-text available via subscription   (Followers: 521)
Network Modeling and Analysis in Health Informatics and Bioinformatics     Hybrid Journal   (Followers: 3)
New Biotechnology     Hybrid Journal   (Followers: 4)
Nigerian Journal of Biotechnology     Open Access  
Nova Biotechnologica et Chimica     Open Access  
NPG Asia Materials     Open Access  
npj Biofilms and Microbiomes     Open Access  
OA Biotechnology     Open Access  
Plant Biotechnology Journal     Open Access   (Followers: 10)
Plant Biotechnology Reports     Hybrid Journal   (Followers: 4)
Preparative Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)

        1 2 | Last

Journal Cover Journal of Experimental Biology
  [SJR: 1.815]   [H-I: 135]   [25 followers]  Follow
   Full-text available via subscription Subscription journal
   ISSN (Print) 0022-0949 - ISSN (Online) 1477-9145
   Published by Company of Biologists, The Homepage  [5 journals]
  • Farewell Steve and welcome Pat and Katie [NEWS]
    • Authors: Knight K.
      Abstract: Kathryn Knight

      PubDate: 2018-03-14T08:18:41-07:00
      DOI: 10.1242/jeb.180083
      Issue No: Vol. 221, No. 5 (2018)
  • Negligible differences in metabolism and thermal tolerance between diploid
           and triploid Atlantic salmon (Salmo salar) [RESEARCH ARTICLE]
    • Authors: Bowden, A. J; Andrewartha, S. J, Elliott, N. G, Frappell, P. B, Clark, T. D.
      Abstract: Alyssa J. Bowden, Sarah J. Andrewartha, Nick G. Elliott, Peter B. Frappell, and Timothy D. Clark

      The mechanisms that underlie thermal tolerance in aquatic ectotherms remain unresolved. Triploid fish have been reported to exhibit lower thermal tolerance than diploids, offering a potential model organism to better understand the physiological drivers of thermal tolerance. Here, we compared triploid and diploid juvenile Atlantic salmon (Salmo salar) in freshwater to investigate the proposed link between aerobic capacity and thermal tolerance. We measured specific growth rates (SGR) and resting (aerobic) metabolic rates (RMR) in freshwater at 3, 7 and 9 weeks of acclimation to 10, 14 and 18°C. Additionally, maximum metabolic rates (MMR) were measured at 3 and 7 weeks of acclimation, and critical thermal maxima (CTmax) were measured at 9 weeks. Mass, SGR and RMR differed between ploidies across all temperatures at the beginning of the acclimation period, but all three metrics were similar across ploidies by week 7. Aerobic scope (MMR–RMR) remained consistent across ploidies, acclimation temperatures and time. At 9 weeks, CTmax was independent of ploidy, but correlated positively with acclimation temperature despite the similar aerobic scope between acclimation groups. Our findings suggest that acute thermal tolerance is not modulated by aerobic scope, and the altered genome of triploid Atlantic salmon does not translate to reduced thermal tolerance of juvenile fish in freshwater.
      PubDate: 2018-03-13T06:50:14-07:00
      DOI: 10.1242/jeb.166975
      Issue No: Vol. 221, No. 5 (2018)
  • Limits to sustained energy intake. XXVII. Trade-offs between first and
           second litters in lactating mice support the ecological context hypothesis
    • Authors: Vaanholt, L. M; Duah, O. A, Balduci, S, Mitchell, S. E, Hambly, C, Speakman, J. R.
      Abstract: Lobke M. Vaanholt, Osei A. Duah, Suzanna Balduci, Sharon E. Mitchell, Catherine Hambly, and John R. Speakman

      Increased reproductive effort may lead to trade-offs with future performance and impact offspring, thereby influencing optimal current effort level. We experimentally enlarged or reduced litter size in mice during their first lactation, and then followed them through a successive unmanipulated lactation. Measurements of food intake, body mass, milk energy output (MEO), litter size and litter mass were taken. Offspring from the first lactation were also bred to investigate their reproductive success. In their first lactation, mothers with enlarged litters (n=9, 16 pups) weaned significantly smaller pups, culled more pups, and increased MEO and food intake compared with mothers with reduced litters (n=9, 5 pups). In the second lactation, no significant differences in pup mass or litter size were observed between groups, but mothers that had previously reared enlarged litters significantly decreased pup mass, MEO and food intake compared with those that had reared reduced litters. Female offspring from enlarged litters weaned slightly smaller pups than those from reduced litters, but displayed no significant differences in any of the other variables measured. These results suggest that females with enlarged litters suffered from a greater energetic burden during their first lactation, and this was associated with lowered performance in a successive reproductive event and impacted on their offspring's reproductive performance. Female ‘choice’ about how much to invest in the first lactation may thus be driven by trade-offs with future reproductive success. Hence, the ‘limit’ on performance may not be a hard physiological limit. These data support the ecological context hypothesis.
      PubDate: 2018-03-13T06:50:14-07:00
      DOI: 10.1242/jeb.170902
      Issue No: Vol. 221, No. 5 (2018)
  • Pheromones modulate responsiveness to a noxious stimulus in honey bees
    • Authors: Rossi, N; d'Ettorre, P, Giurfa, M.
      Abstract: Natacha Rossi, Patrizia d'Ettorre, and Martin Giurfa

      Pheromones are chemical substances released into the environment by an individual, which trigger stereotyped behaviors and/or physiological processes in individuals of the same species. Yet, a novel hypothesis has suggested that pheromones not only elicit innate responses but also contribute to behavioral plasticity by affecting the subjective evaluation of appetitive or aversive stimuli. To test this hypothesis, we exposed bees to three pheromonal components whose valence was either negative (i.e. associated with aversive events: isopentyl acetate and 2-heptanone) or positive (i.e. associated with appetitive events: geraniol). We then determined the effect of this exposure on the subjective evaluation of aversive stimuli by quantifying responsiveness to a series of increasing electric shock voltages before and after exposure. Two experiments were conducted varying the time lapse between shock series (15 min in experiment 1, and 24 h in experiment 2). In experiment 1, we observed a general decrease of shock responsiveness caused by fatigue, due to the short lapse of time between the two series of shocks. This decrease could only be counteracted by isopentyl acetate. The enhancing effect of isopentyl acetate on shock responsiveness was also found in experiment 2. Conversely, geraniol decreased aversive responsiveness in this experiment; 2-heptanone did not affect aversive responsiveness in any experiment. Overall, our results demonstrate that certain pheromones modulate the salience of aversive stimuli according to their valence. In this way, they would affect the motivation to engage in aversive responses, thus acting as modulators of behavioral plasticity.
      PubDate: 2018-03-13T06:50:14-07:00
      DOI: 10.1242/jeb.172270
      Issue No: Vol. 221, No. 5 (2018)
  • Mouse mums consider their futures [INSIDE JEB]
    • Authors: Gilman C.
      Abstract: Casey Gilman

      PubDate: 2018-03-13T06:50:14-07:00
      DOI: 10.1242/jeb.177139
      Issue No: Vol. 221, No. 5 (2018)
  • Pheromones fiddle with bee perception [INSIDE JEB]
    • Authors: Knight K.
      Abstract: Kathryn Knight

      PubDate: 2018-03-13T06:50:14-07:00
      DOI: 10.1242/jeb.178426
      Issue No: Vol. 221, No. 5 (2018)
  • Cold temperature represses daily rhythms in the liver transcriptome of a
           stenothermal teleost under decreasing day length [RESEARCH ARTICLE]
    • Authors: Prokkola, J. M; Nikinmaa, M, Lewis, M, Anttila, K, Kanerva, M, Ikkala, K, Seppänen, E, Kolari, I, Leder, E. H.
      Abstract: Jenni M. Prokkola, Mikko Nikinmaa, Mario Lewis, Katja Anttila, Mirella Kanerva, Kaisa Ikkala, Eila Seppänen, Irma Kolari, and Erica H. Leder

      The climate-change-driven increase in temperature is occurring rapidly and decreasing the predictability of seasonal rhythms at high latitudes. It is therefore urgent to understand how a change in the relationship between photoperiod and temperature can affect ectotherms in these environments. We tested whether temperature affects daily rhythms of transcription in a cold-adapted salmonid using high-throughput RNA sequencing. Arctic char (Salvelinus alpinus) from a subarctic population were reared at a high and a low temperature (15 and 8°C) for 1 month under natural, decreasing day length during late summer. Liver transcriptomes were compared between samples collected in the middle and towards the end of the light period and in the middle of the dark period. Daily variation in transcription was lower in fish from the low temperature compared with strong daily variation in warm-acclimated fish, suggesting that cold temperatures dampen the cycling of transcriptional rhythms under a simultaneously decreasing day length. Different circadian clock genes had divergent expression patterns, responding either by decreased expression or by increased rhythmicity at 15°C compared with 8°C. The results point out mechanisms that can affect the ability of fish to adapt to increasing temperatures caused by climate change.
      PubDate: 2018-03-12T11:06:38-07:00
      DOI: 10.1242/jeb.170670
      Issue No: Vol. 221, No. 5 (2018)
  • Carbonic anhydrase expression in the branchial ionocytes of rainbow trout
    • Authors: Brannen, M; Gilmour, K. M.
      Abstract: Michael Brannen and Kathleen M. Gilmour

      Rainbow trout (Oncorhynchus mykiss) exposed to acid–base challenges activate branchial mechanisms for the excretion of acid–base equivalents. Current models of branchial acid–base excretion in freshwater rainbow trout propose two main ionocyte types: the peanut lectin agglutinin-positive (PNA+) mitochondrion-rich cell or ionocyte is believed to secrete HCO3– in exchange for Cl–, whereas H+ secretion is thought to occur across PNA– ionocytes in exchange for Na+. Both HCO3– and H+ are supplied by intracellular hydration of CO2 catalysed by cytosolic carbonic anhydrase (CAc). Immunohistochemical approaches revealed that under control conditions, CAc was detectable in 92.3±1.0% (N=11) of PNA– ionocytes, and the abundance of PNA– ionocytes increased in response to systemic acidosis elicited by 72 h exposure to water of low pH (nominally pH 4.5), hypercapnia (1% CO2, nominally 7.6 Torr) or hyperoxia (achieved by gassing water with pure O2), as did the abundance of PNA– ionocytes that exhibited immunofluorescence for CAc. However, just 4.3±0.6% (N=11) of PNA+ ionocytes expressed detectable CAc under control conditions. Marked increases in the abundance of CAc-positive PNA+ ionocytes were detected following exposure of trout to a base load via recovery from hypercapnia or base infusion (72 h infusion with 140 mmol l–1 NaHCO3). The percentage of CAc-positive PNA+ ionocytes also was increased in trout treated with cortisol (10 mg kg–1 hydrocortisone 21-hemisuccinate daily for 7 days). These results suggest that regulation of CA within PNA+ ionocytes and/or the abundance of CAc-positive PNA+ ionocytes plays a role in activating base secretion in response to systemic alkalosis.
      PubDate: 2018-03-12T10:55:20-07:00
      DOI: 10.1242/jeb.164582
      Issue No: Vol. 221, No. 5 (2018)
  • Sticky tree frogs can also get a grip [INSIDE JEB]
    • Authors: Knight K.
      Abstract: Kathryn Knight

      PubDate: 2018-03-12T10:45:53-07:00
      DOI: 10.1242/jeb.177642
      Issue No: Vol. 221, No. 5 (2018)
  • The biomechanics of tree frogs climbing curved surfaces: a gripping
           problem [RESEARCH ARTICLE]
    • Authors: Hill, I. D. C; Dong, B, Barnes, W. J. P, Ji, A, Endlein, T.
      Abstract: Iain D. C. Hill, Benzheng Dong, W. Jon P. Barnes, Aihong Ji, and Thomas Endlein

      The adhesive mechanisms of climbing animals have become an important research topic because of their biomimetic implications. We examined the climbing abilities of hylid tree frogs on vertical cylinders of differing diameter and surface roughness to investigate the relative roles of adduction forces (gripping) and adhesion. Tree frogs adhere using their toe pads and subarticular tubercles, the adhesive joint being fluid-filled. Our hypothesis was that on an effectively flat surface (adduction forces on the largest 120 mm diameter cylinder were insufficient to allow climbing), adhesion would effectively be the only means by which tree frogs could climb, but on the 44 and 13 mm diameter cylinders, frogs could additionally utilise adduction forces by gripping the cylinder either with their limbs outstretched or by grasping around the cylinder with their digits, respectively. The frogs' performance would also depend on whether the surfaces were smooth (easy to adhere to) or rough (relatively non-adhesive). Our findings showed that climbing performance was highest on the narrowest smooth cylinder. Frogs climbed faster, frequently using a ‘walking trot’ gait rather than the ‘lateral sequence walk’ used on other cylinders. Using an optical technique to visualise substrate contact during climbing on smooth surfaces, we also observed an increasing engagement of the subarticular tubercles on the narrower cylinders. Finally, on the rough substrate, frogs were unable to climb the largest diameter cylinder, but were able to climb the narrowest one slowly. These results support our hypotheses and have relevance for the design of climbing robots.
      Keywords: Comparative biomechanics of movement
      PubDate: 2018-03-12T10:45:52-07:00
      DOI: 10.1242/jeb.168179
      Issue No: Vol. 221, No. 5 (2018)
  • Auditory neural networks involved in attention modulation prefer
           biologically significant sounds and exhibit sexual dimorphism in anurans
    • Authors: Xue, F; Yue, X, Fan, Y, Cui, J, Brauth, S. E, Tang, Y, Fang, G.
      Abstract: Fei Xue, Xizi Yue, Yanzhu Fan, Jianguo Cui, Steven E. Brauth, Yezhong Tang, and Guangzhan Fang

      Allocating attention to biologically relevant stimuli in a complex environment is critically important for survival and reproductive success. In humans, attention modulation is regulated by the frontal cortex, and is often reflected by changes in specific components of the event-related potential (ERP). Although brain networks for attention modulation have been widely studied in primates and avian species, little is known about attention modulation in amphibians. The present study aimed to investigate the attention modulation networks in an anuran species, the Emei music frog (Babina daunchina). Male music frogs produce advertisement calls from within underground nest burrows that modify the acoustic features of the calls, and both males and females prefer calls produced from inside burrows. We broadcast call stimuli to male and female music frogs while simultaneously recording electroencephalographic (EEG) signals from the telencephalon and mesencephalon. Granger causal connectivity analysis was used to elucidate functional brain networks within the time window of ERP components. The results show that calls produced from inside nests which are highly sexually attractive result in the strongest brain connections; both ascending and descending connections involving the left telencephalon were stronger in males while those in females were stronger with the right telencephalon. Our findings indicate that the frog brain allocates neural attention resources to highly attractive sounds within the window of early components of ERP, and that such processing is sexually dimorphic, presumably reflecting the different reproductive strategies of males and females.
      PubDate: 2018-03-09T07:03:03-08:00
      DOI: 10.1242/jeb.167775
      Issue No: Vol. 221, No. 5 (2018)
  • Through the eye of a lizard: hue discrimination in a lizard with ventral
           polymorphic coloration [RESEARCH ARTICLE]
    • Authors: Perez i de Lanuza, G; Abalos, J, Bartolome, A, Font, E.
      Abstract: Guillem Perez i de Lanuza, Javier Abalos, Alicia Bartolome, and Enrique Font

      Colour polymorphisms are thought to be maintained by complex evolutionary processes, some of which require that the colours of the alternative morphs function as chromatic signals to conspecifics. Unfortunately, a key aspect of this hypothesis has rarely been studied: whether the study species perceives its own colour variation as discrete rather than continuous. The European common wall lizard (Podarcis muralis) presents a striking colour polymorphism: the ventral surface of adults of both sexes may be coloured orange, white, yellow or with a mosaic of scales combining two colours (orange–white, orange–yellow). Here, we used a discrimination learning paradigm to test whether P. muralis is capable of discriminating colour stimuli designed to match the ventral colours of conspecifics. We trained 20 lizards to eat from colour-coded wells bored in wooden blocks. Blocks had four colour-coded wells (orange, white, yellow and an achromatic control), but only one contained food (mealworm larvae). After six trials, the lizards performed significantly better than expected by chance, showing a decrease in both the number of wells explored and the latency to finding the food. Using visual modelling techniques, we found that, based on their spectral properties and the lizards' cone sensitivities, the ventral colours of P. muralis correspond to discrete rather than continuous colour categories, and that colour discriminability (i.e. distance in perceptual space) varies depending on the morphs compared, which may have implications for signal detection and discrimination. These results suggest that P. muralis can discriminate hue differences matching their own ventral colour variation.
      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.169565
      Issue No: Vol. 221, No. 5 (2018)
  • Slow swimming exhausts fish [OUTSIDE JEB]
    • Authors: Stenum J.
      Abstract: Jan Stenum

      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.169854
      Issue No: Vol. 221, No. 5 (2018)
  • Salmon nourish their children even after death [OUTSIDE JEB]
    • Authors: Stawski C.
      Abstract: Clare Stawski

      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.169896
      Issue No: Vol. 221, No. 5 (2018)
  • An off-the-(nar)whal stress response [OUTSIDE JEB]
    • Authors: Regan M. D.
      Abstract: Matthew D. Regan

      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.169904
      Issue No: Vol. 221, No. 5 (2018)
  • Flying is not for the small-hearted [OUTSIDE JEB]
    • Authors: Joyce W.
      Abstract: William Joyce

      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.169912
      Issue No: Vol. 221, No. 5 (2018)
  • Disembodying the invisible: electrocommunication and social interactions
           by passive reception of a moving playback signal [RESEARCH ARTICLE]
    • Authors: Worm, M; Kirschbaum, F, von der Emde, G.
      Abstract: Martin Worm, Frank Kirschbaum, and Gerhard von der Emde

      Mormyrid weakly electric fish have a special electrosensory modality that allows them to actively sense their environment and to communicate with conspecifics by emitting sequences of electric signals. Electroreception is mediated by different types of dermal electroreceptor organs for active electrolocation and electrocommunication, respectively. During electrocommunication, mormyrids exhibit stereotyped discharge sequences and locomotor patterns, which can be induced by playback of electric signals. This raises the question: what sensory information is required to initiate and sustain social interactions, and which electrosensory pathway mediates such interactions' By experimentally excluding stimuli from vision and the lateral line system, we show that Mormyrus rume proboscirostris can rely exclusively on its electrosensory system to track a mobile source of electric communication signals. Detection of electric playback signals induced discharge cessations, followed by double-pulse patterns. The animals tried to interact with the moving signal source and synchronized their discharge activity to the playback. These behaviors were absent in control trials without playback. Silencing the electric organ in some fish did not impair their ability to track the signal source. Silenced fish followed on trajectories similar to those obtained from intact animals, indicating that active electrolocation is no precondition for close-range interactions based on electrocommunication. However, some silenced animals changed their strategy when searching for the stationary playback source, which indicates passive sensing. Social interactions among mormyrids can therefore be induced and mediated by passive reception of electric communication signals without the need for perception of the location of the signal source through other senses.
      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.172890
      Issue No: Vol. 221, No. 5 (2018)
  • Early career researchers: an interview with Yossi Yovel [CONVERSATION]
    • Abstract:

      Yossi Yovel is an Assistant Professor at Tel-Aviv University, Israel, where he studies bat echolocation. He received his joint honours Bachelor's degree in Biology and Physics before moving to complete his PhD with Hans-Ulrich Schnitzler at University of Tübingen, Germany, in 2008. He then completed postdocs at the Weizmann Institute, Israel, and University of Chicago, USA.
      PubDate: 2018-03-07T06:19:52-08:00
      DOI: 10.1242/jeb.179069
      Issue No: Vol. 221, No. 5 (2018)
  • Aquatic acidification: a mechanism underpinning maintained oxygen
           transport and performance in fish experiencing elevated carbon dioxide
           conditions [REVIEW]
    • Authors: Hannan, K. D; Rummer, J. L.
      Abstract: Kelly D. Hannan and Jodie L. Rummer

      Aquatic acidification, caused by elevating levels of atmospheric carbon dioxide (CO2), is increasing in both freshwater and marine ecosystems worldwide. However, few studies have examined how acidification will affect oxygen (O2) transport and, therefore, performance in fishes. Although data are generally lacking, the majority of fishes investigated in this meta-analysis exhibited no effect of elevated CO2 at the level of O2 uptake, suggesting that they are able to maintain metabolic performance during a period of acidosis. Notably, the mechanisms that fish employ to maintain performance and O2 uptake have yet to be verified. Here, we summarize current data related to one recently proposed mechanism underpinning the maintenance of O2 uptake during exposure to aquatic acidification, and reveal knowledge gaps that could be targeted for future research. Most studies have examined O2 uptake rates while fishes were resting and did not calculate aerobic scope, even though aerobic scope can aid in predicting changes to whole-animal metabolic performance. Furthermore, research is lacking on different age classes, freshwater species and elasmobranchs, all of which might be impacted by future acidification conditions. Finally, this Review further seeks to emphasize the importance of developing collaborative efforts between molecular, physiological and ecological approaches in order to provide more comprehensive predictions as to how future fish populations will be affected by climate change.
      Keywords: Ecophysiology: responses to environmental stressors and change
      PubDate: 2018-03-07T05:33:51-08:00
      DOI: 10.1242/jeb.154559
      Issue No: Vol. 221, No. 5 (2018)
  • Biomechanical mechanisms underlying exosuit-induced improvements in
           walking economy after stroke [RESEARCH ARTICLE]
    • Authors: Bae, J; Awad, L. N, Long, A, O'Donnell, K, Hendron, K, Holt, K. G, Ellis, T. D, Walsh, C. J.
      Abstract: Jaehyun Bae, Louis N. Awad, Andrew Long, Kathleen O'Donnell, Katy Hendron, Kenneth G. Holt, Terry D. Ellis, and Conor J. Walsh

      Stroke-induced hemiparetic gait is characteristically asymmetric and metabolically expensive. Weakness and impaired control of the paretic ankle contribute to reduced forward propulsion and ground clearance – walking subtasks critical for safe and efficient locomotion. Targeted gait interventions that improve paretic ankle function after stroke are therefore warranted. We have developed textile-based, soft wearable robots that transmit mechanical power generated by off-board or body-worn actuators to the paretic ankle using Bowden cables (soft exosuits) and have demonstrated the exosuits can overcome deficits in paretic limb forward propulsion and ground clearance, ultimately reducing the metabolic cost of hemiparetic walking. This study elucidates the biomechanical mechanisms underlying exosuit-induced reductions in metabolic power. We evaluated the relationships between exosuit-induced changes in the body center of mass (COM) power generated by each limb, individual joint power and metabolic power. Compared with walking with an exosuit unpowered, exosuit assistance produced more symmetrical COM power generation during the critical period of the step-to-step transition (22.4±6.4% more symmetric). Changes in individual limb COM power were related to changes in paretic (R2=0.83, P=0.004) and non-paretic (R2=0.73, P=0.014) ankle power. Interestingly, despite the exosuit providing direct assistance to only the paretic limb, changes in metabolic power were related to changes in non-paretic limb COM power (R2=0.80, P=0.007), not paretic limb COM power (P>0.05). These findings contribute to a fundamental understanding of how individuals post-stroke interact with an exosuit to reduce the metabolic cost of hemiparetic walking.
      Keywords: Comparative biomechanics of movement
      PubDate: 2018-03-07T05:33:51-08:00
      DOI: 10.1242/jeb.168815
      Issue No: Vol. 221, No. 5 (2018)
  • Benefits of hyperbaric oxygen pretreatment for decompression sickness in
           Bama pigs [RESEARCH ARTICLE]
    • Authors: Qing, L; Yi, H.-j, Wang, Y.-w, Zhou, Q, Ariyadewa, D. K, Xu, W.-g.
      Abstract: Long Qing, Hong-jie Yi, Ye-wei Wang, Quan Zhou, Dinesh K. Ariyadewa, and Wei-gang Xu

      Decompression sickness (DCS) occurs when ambient pressure is severely reduced during diving and aviation. Hyperbaric oxygen (HBO) pretreatment has been shown to exert beneficial effects on DCS in rats via heat-shock proteins (HSPs). We hypothesized that HBO pretreatment will also reduce DCS via HSPs in swine models. In the first part of our investigation, six swine were subjected to a session of HBO treatment. HSP32, 60, 70 and 90 were detected, before and at 6, 12, 18, 24 and 30 h following exposure in lymphocytes. In the second part of our investigation, another 10 swine were randomly assigned into two groups (five per group). All swine were subjected to two simulated air dives in a hyperbaric chamber with an interval of 7 days. Eighteen hours before each dive, the swine were pretreated with HBO or air: the first group received air pretreatment prior to the first dive and HBO pretreatment prior to the second; the second group were pretreated with HBO first and then air. Bubble loads, skin lesions, inflammation and endothelial markers were detected after each dive. In lymphocytes, all HSPs increased significantly (P
      PubDate: 2018-03-07T05:33:51-08:00
      DOI: 10.1242/jeb.171066
      Issue No: Vol. 221, No. 5 (2018)
  • Malpighian tubules of Trichoplusia ni: recycling ions via gap junctions
           and switching between secretion and reabsorption of Na+ and K+ in the
           distal ileac plexus [RESEARCH ARTICLE]
    • Authors: Kolosov, D; Piermarini, P. M, O'Donnell, M. J.
      Abstract: Dennis Kolosov, Peter M. Piermarini, and Michael J. O'Donnell

      The functional kidney in insects consists of the Malpighian tubules and hindgut. Malpighian tubules secrete ions and fluid aiding in hydromineral homeostasis, acid–base balance and metabolic waste excretion. In many insects, including lepidopterans, the Malpighian tubule epithelium consists of principal cells (PCs) and secondary cells (SCs). The SCs in the Malpighian tubules of larvae of the lepidopteran Trichoplusia ni have been shown to reabsorb K+, transporting it in a direction opposite to that in the neighbouring PCs that secrete K+. One of the mechanisms that could enable such an arrangement is a gap junction (GJ)-based coupling of the two cell types. In the current study, we have immunolocalized GJ protein Innexin-2 to the PC–PC and SC–PC cell–cell borders. We have demonstrated that GJs in the SC-containing region of the Malpighian tubules enable Na+ and K+ reabsorption by the SCs. We also demonstrated that in ion-loaded animals, PCs switch from Na+/K+ secretion to reabsorption, resulting in an ion-transporting phenotype similar to that of tubules with pharmacologically blocked GJs. Concomitantly, mRNA abundance encoding GJ proteins was downregulated. Finally, we observed that such PC-based reabsorption was only present in the distal ileac plexus connected to the rectal complex. We propose that this plasticity in the PC function in the distal ileac plexus is likely to be aimed at providing an ion supply for the SC function in this segment of the tubule.
      PubDate: 2018-03-07T05:33:51-08:00
      DOI: 10.1242/jeb.172296
      Issue No: Vol. 221, No. 5 (2018)
  • Cold tolerance is linked to osmoregulatory function of the hindgut in
           Locusta migratoria [RESEARCH ARTICLE]
    • Authors: Gerber, L; Overgaard, J.
      Abstract: Lucie Gerber and Johannes Overgaard

      There is growing evidence that maintenance of ion and water balance determines cold tolerance in many insects. The hindgut of terrestrial insects is critical for maintaining organismal homeostasis as it regulates solute and water balance of the haemolymph. Here, we used ex vivo everted gut sacs of Locusta migratoria to examine the effects of temperature (0–30°C), thermal acclimation, hypoxia, and ionic and osmotic forces on bulk water and ion (Na+, K+ and Cl–) movement across the rectal epithelium. These findings were related to simultaneous in vivo measurements of water and ion balance in locusts exposed to similar temperatures. As predicted, we observed a critical inhibition of net water and ion reabsorption at low temperature that was proportional to the in vivo loss of water and ion homeostasis. Further, cold-acclimated locusts, which are known to defend ion and water balance at low temperature, were characterised by improved reabsorptive capacity at low temperature. These findings strongly support the hypothesis that transport mechanisms in the hindgut at low temperature are essential for cold tolerance. The loss of osmoregulatory capacity at low temperature was primarily caused by reduced active transport, while rectal paracellular permeability to fluorescein isothiocyanate dextran was unchanged at 0 and 30°C. During cold exposure, water reabsorption was independent of major cation gradients across the epithelia, while a reduction in mucosal Cl– availability and an increase in mucosal osmolality markedly depressed water reabsorption. These findings are discussed in the context of existing knowledge and with suggestions for future physiological studies on cold acclimation and adaptation in insects.
      PubDate: 2018-03-07T05:33:51-08:00
      DOI: 10.1242/jeb.173930
      Issue No: Vol. 221, No. 5 (2018)
  • The loss of hemoglobin and myoglobin does not minimize oxidative stress in
           Antarctic icefishes [RESEARCH ARTICLE]
    • Authors: O'Brien, K. M; Crockett, E. L, Philip, J, Oldham, C. A, Hoffman, M, Kuhn, D. E, Barry, R, McLaughlin, J.
      Abstract: Kristin M. O'Brien, Elizabeth L. Crockett, Jacques Philip, Corey A. Oldham, Megan Hoffman, Donald E. Kuhn, Ronald Barry, and Jessica McLaughlin

      The unusual pattern of expression of hemoglobin (Hb) and myoglobin (Mb) among Antarctic notothenioid fishes provides an exceptional model system for assessing the impact of these proteins on oxidative stress. We tested the hypothesis that the lack of oxygen-binding proteins may reduce oxidative stress. Levels and activity of pro-oxidants and small-molecule and enzymatic antioxidants, and levels of oxidized lipids and proteins in the liver, oxidative skeletal muscle and heart ventricle were quantified in five species of notothenioid fishes differing in the expression of Hb and Mb. Levels of ubiquitinated proteins and rates of protein degradation by the 20S proteasome were also quantified. Although levels of oxidized proteins and lipids, ubiquitinated proteins, and antioxidants were higher in red-blooded fishes than in Hb-less icefishes in some tissues, this pattern did not persist across all tissues. Expression of Mb was not associated with oxidative damage in the heart ventricle, whereas the activity of citrate synthase and the contents of heme were positively correlated with oxidative damage in most tissues. Despite some tissue differences in levels of protein carbonyls among species, rates of degradation by the 20S proteasome were not markedly different, suggesting either alternative pathways for eliminating oxidized proteins or that redox tone varies among species. Together, our data indicate that the loss of Hb and Mb does not correspond with a clear pattern of either reduced oxidative defense or oxidative damage.
      PubDate: 2018-03-01T07:40:12-08:00
      DOI: 10.1242/jeb.162503
      Issue No: Vol. 221, No. 5 (2018)
  • The reluctant visitor: an alkaloid in toxic nectar can reduce olfactory
           learning and memory in Asian honey bees [RESEARCH ARTICLE]
    • Authors: Zhang, J; Wang, Z, Wen, P, Qu, Y, Tan, K, Nieh, J. C.
      Abstract: Junjun Zhang, Zhengwei Wang, Ping Wen, Yufeng Qu, Ken Tan, and James C. Nieh

      The nectar of the thunder god vine, Tripterygium hypoglaucum, contains a terpenoid, triptolide (TRP), that may be toxic to the sympatric Asian honey bee, Apis cerana, because honey produced from this nectar is toxic to bees. However, these bees will forage on, recruit for, and pollinate this plant during a seasonal dearth of preferred food sources. Olfactory learning plays a key role in forager constancy and pollination, and we therefore tested the effects of acute and chronic TRP feeding on forager olfactory learning, using proboscis extension reflex conditioning. At concentrations of 0.5–10 µg TRP ml–1, there were no learning effects of acute exposure. However, memory retention (1 h after the last learning trial) significantly decreased by 56% following acute consumption of 0.5 µg TRP ml–1. Chronic exposure did not alter learning or memory, except at high concentrations (5 and 10 µg TRP ml–1). TRP concentrations in nectar may therefore not significantly harm plant pollination. Surprisingly, TRP slightly increased bee survival, and thus other components in T. hypoglaucum honey may be toxic. Long-term exposure to TRP could have colony effects but these may be ameliorated by the bees’ aversion to T. hypoglaucum nectar when other food sources are available and, perhaps, by detoxification mechanisms. The co-evolution of this plant and its reluctant visitor may therefore likely illustrate a classic compromise between the interests of both actors.
      PubDate: 2018-03-01T07:40:12-08:00
      DOI: 10.1242/jeb.168344
      Issue No: Vol. 221, No. 5 (2018)
  • Size-dependent avoidance of a strong magnetic anomaly in Caribbean spiny
           lobsters [RESEARCH ARTICLE]
    • Authors: Ernst, D. A; Lohmann, K. J.
      Abstract: David A. Ernst and Kenneth J. Lohmann

      On a global scale, the geomagnetic field varies predictably across the Earth's surface, providing animals that migrate long distances with a reliable source of directional and positional information that can be used to guide their movements. In some locations, however, magnetic minerals in the Earth's crust generate an additional field that enhances or diminishes the overall field, resulting in unusually steep gradients of field intensity within a limited area. How animals respond to such magnetic anomalies is unclear. The Caribbean spiny lobster, Panulirus argus, is a benthic marine invertebrate that possesses a magnetic sense and is likely to encounter magnetic anomalies during migratory movements and homing. As a first step toward investigating whether such anomalies affect the behavior of lobsters, a two-choice preference experiment was conducted in which lobsters were allowed to select one of two artificial dens, one beneath a neodymium magnet and the other beneath a non-magnetic weight of similar size and mass (control). Significantly more lobsters selected the control den, demonstrating avoidance of the magnetic anomaly. In addition, lobster size was found to be a significant predictor of den choice: lobsters that selected the anomaly den were significantly smaller as a group than those that chose the control den. Taken together, these findings provide additional evidence for magnetoreception in spiny lobsters, raise the possibility of an ontogenetic shift in how lobsters respond to magnetic fields, and suggest that magnetic anomalies might influence lobster movement in the natural environment.
      PubDate: 2018-03-01T07:40:12-08:00
      DOI: 10.1242/jeb.172205
      Issue No: Vol. 221, No. 5 (2018)
  • Lizards assess complex social signals by lateralizing colour but not
           motion detection [SHORT COMMUNICATION]
    • Authors: Batabyal, A; Thaker, M.
      Abstract: Anuradha Batabyal and Maria Thaker

      Vertebrates lateralize many behaviours including social interactions. Social displays typically comprise multiple components, yet our understanding of how these are processed comes from studies that typically examine responses to the dominant component or the complex signal as a whole. Here, we examined laterality in lizard responses to determine whether receivers separate the processing of motion and colour signal components in different brain hemispheres. In Psammophilus dorsalis, males display colours that dynamically change during courtship and aggressive interactions. We tested the visual grasp reflex of both sexes using robotic stimuli that mimicked two signal components: (1) multiple speeds of head-bobbing behaviour and (2) multiple colours. We found no laterality in response to different motion stimuli, indicating that motion similarly attracts attention from the two visual fields across sexes. Notably, receivers showed left visual field dominance to colours, especially when males were exposed to ‘aggression-specific’ colours and females to ‘courtship-specific’ colours.
      PubDate: 2018-03-01T07:40:12-08:00
      DOI: 10.1242/jeb.173252
      Issue No: Vol. 221, No. 5 (2018)
  • Light exposure enhances urea absorption in the fluted giant clam, Tridacna
           squamosa, and up-regulates the protein abundance of a light-dependent urea
           active transporter, DUR3-like, in its ctenidium [RESEARCH ARTICLE]
    • Authors: Chan, C. Y. L; Hiong, K. C, Boo, M. V, Choo, C. Y. L, Wong, W. P, Chew, S. F, Ip, Y. K.
      Abstract: Christabel Y. L. Chan, Kum C. Hiong, Mel V. Boo, Celine Y. L. Choo, Wai P. Wong, Shit F. Chew, and Yuen K. Ip

      Giant clams live in nutrient-poor reef waters of the Indo-Pacific and rely on symbiotic dinoflagellates (Symbiodinium spp., also known as zooxanthellae) for nutrients. As the symbionts are nitrogen deficient, the host clam has to absorb exogenous nitrogen and supply it to them. This study aimed to demonstrate light-enhanced urea absorption in the fluted giant clam, Tridacna squamosa, and to clone and characterize the urea active transporter, DUR3-like, from its ctenidium (gill). Results indicate that T. squamosa could absorb exogenous urea, and the rate of urea uptake in light was significantly higher than that in darkness. The DUR3-like coding sequence obtained from its ctenidium comprised 2,346 bp, encoding a protein of 782 amino acids and 87.0 kDa. DUR3-like was expressed strongly in the ctenidium, outer mantle and kidney. Twelve hours of exposure to light had no significant effect on the transcript level of ctenidial DUR3-like. However, between hour 3 and hour 12 h of light exposure, the DUR3-like protein abundance increased progressively in the ctenidium, and became significantly greater than the control at hour 12. The DUR3-like had an apical localization in the epithelia of the ctenidial filaments and tertiary water channels. Taken together, these results indicate that the DUR3-like might participate in light-enhanced urea absorption in the ctenidium of T. squamosa. When made available to the symbiotic zooxanthellae that are known to possess urease, the absorbed urea can be metabolized to NH3 and CO2 to support amino acid synthesis and photosynthesis, respectively, during insolation.
      PubDate: 2018-03-14T10:22:42-07:00
      DOI: 10.1242/jeb.176313
  • Hand pressures during arboreal locomotion in captive bonobos (Pan
           paniscus) [RESEARCH ARTICLE]
    • Authors: Samuel, D. S; Nauwelaerts, S, Stevens, J. M. G, Kivell, T. L.
      Abstract: Diana S. Samuel, Sandra Nauwelaerts, Jeroen M. G. Stevens, and Tracy L. Kivell

      Evolution of the human hand has undergone a transition from use during locomotion to use primarily for manipulation. Previous comparative morphological and biomechanical studies have focused on potential changes in manipulative abilities during human hand evolution, but few have focused on functional signals for arboreal locomotion. Here, we provide this comparative context though the first analysis of hand loading in captive bonobos during arboreal locomotion. We quantify pressure experienced by the fingers, palm and thumb in bonobos during vertical locomotion, suspension and arboreal knuckle-walking. Results show that pressure experienced by the fingers is significantly higher during knuckle-walking compared with similar pressures experienced by the fingers and palm during suspensory and vertical locomotion. Peak pressure is most often experienced at or around the third digit in all locomotor modes. Pressure quantified for the thumb is either very low or absent, despite the thumb making contact with the substrate during all suspensory and vertical locomotor trials. Unlike chimpanzees, the bonobos do not show a rolling pattern of digit contact with the substrate during arboreal knuckle-walking but, instead, digits 3 and 4 typically touch down first and digit 5 almost always made contact with the substrate. These results have implications for interpreting extant and fossilised hand morphology; we expect bonobo (and chimpanzee) bony morphology to primarily reflect the biomechanical loading of knuckle-walking, while functional signals for arboreal locomotion in fossil hominins are most likely to appear in the fingers, particularly digit 3, and least likely to appear in the morphology of the thumb.
      PubDate: 2018-03-14T10:22:42-07:00
      DOI: 10.1242/jeb.170910
  • Environmental acoustic cues guide the biosonar attention of a highly
           specialised echolocator [RESEARCH ARTICLE]
    • Authors: Lattenkamp, E. Z; Kaiser, S, Kaucic, R, Grossmann, M, Koselj, K, Goerlitz, H. R.
      Abstract: Ella Z. Lattenkamp, Samuel Kaiser, Rozle Kaucic, Martina Grossmann, Klemen Koselj, and Holger R. Goerlitz

      Sensory systems experience a trade-off between maximizing the detail and amount of sampled information. This trade-off is particularly pronounced in sensory systems that are highly specialized for a single task and thus experience limitations in other tasks. We hypothesised that combining sensory input from multiple streams of information may resolve this trade-off and improve detection and sensing reliability. Specifically, we predicted that perceptive limitations experienced by animals reliant on specialised active echolocation can be compensated for by the phylogenetically older and less specialised process of passive hearing. We tested this hypothesis in greater horseshoe bats, which possess morphological and neural specialisations allowing them to identify fluttering prey in dense vegetation using echolocation only. At the same time, their echolocation system is both spatially and temporally severely limited. Here we show that greater horseshoe bats employ passive hearing to initially detect and localise prey-generated and other environmental sounds, and then raise vocalisation level and concentrate the scanning movements of their sonar beam on the sound source for further investigation with echolocation. These specialised echolocators thus supplement echo-acoustic information with environmental acoustic cues, enlarging perceived space beyond their biosonar range. Contrary to our predictions, we did not find consistent preferences for prey-related acoustic stimuli, indicating the use of passive acoustic cues also for detection of non-prey objects. Our findings suggest that even specialised echolocators exploit a wide range of environmental information, and that phylogenetically older sensory systems can support the evolution of sensory specialisations by compensating for their limitations.
      PubDate: 2018-03-14T10:22:41-07:00
      DOI: 10.1242/jeb.165696
  • Energetic costs of performance in trained and untrained Anolis
           carolinensis lizards [SHORT COMMUNICATION]
    • Authors: Lailvaux, S. P; Wang, A. Z, Husak, J. F.
      Abstract: Simon P. Lailvaux, Andrew Z. Wang, and Jerry F. Husak

      The energetic costs of performance constitute a non-trivial component of animals’ daily energetic budgets. However, we currently lack an understanding of how those costs are partitioned among the various stages of performance development, maintenance, and production. We manipulated individual investment in performance by training Anolis carolinensis lizards for endurance or sprinting ability. We then measured energetic expenditure both at rest and immediately following exercise to test whether such training alters the maintenance and production costs of performance. Trained lizards had lower resting metabolic rates than controls, suggestive of a maintenance saving associated with enhanced performance as opposed to a cost. Production costs also differed, with sprint-trained lizards incurring the largest energetic performance cost and experiencing the longest recovery times compared to endurance trained and control animals. Although performance training modifies metabolism, production costs are probably the key drivers of trade-offs between performance and other life-history traits in this species.
      PubDate: 2018-03-12T08:22:56-07:00
      DOI: 10.1242/jeb.176867
  • The consequences of seasonal fasting during the dormancy of tegu lizards
           (Salvator merianae) on their postprandial metabolic response [RESEARCH
    • Authors: Gavira, R. S. B; Sartori, M. R, Gontero-Fourcade, M. N, Gomes, B. F, Abe, A. S, Andrade, D. V.
      Abstract: Rodrigo S. B. Gavira, Marina R. Sartori, Manuel N. Gontero-Fourcade, Bruna F. Gomes, Augusto S. Abe, and Denis V. Andrade

      Tegu lizards (Salvator merianae) aestivate for up to 5 months during Brazil's winter, when they retreat to burrows and halt most activities. Dormant tegus reduce their gastrointestinal (GI) mass, which allows a substantial energy economy. This strategy however, implies that the first post-dormancy digestion would be more costly than subsequent feeding episodes due to GI atrophy. To address this, we determined the postprandial metabolic response (SDA) of the first (M1), second (M2) and several (RM) feeding episodes after tegus' dormancy. Another group of tegus (PF) was subjected to an extra 50-days fasting period after arousal. Glucose, triglycerides, and uric acid levels were checked before and after feeding. M1 digestion lasted twice as long and cost two-fold more when compared to M2 or RM, in agreement with the idea that GI atrophy inflates digestion cost at the first post-dormancy meal. SDA response was similar in M2 and RM suggesting that the GI tract was fully reorganized after the first feeding. SDA cost was equal in PF and RM implying that the change in state per se (dormant-to-arousal) triggers the regrowth of GI, independently of feeding. Fasting M1 presented higher triglycerides and lower uric acid levels than fed tegus, indicating that fasting is mainly sustained by fat storages. Our results showed that seasonal fasting imposes an extra digestion cost to tegus following their next feeding, which is fully paid during their first digestion. This surplus cost, however, may be negligible compared to the overall energetic savings provisioned from GI tract atrophy during the dormancy period.
      PubDate: 2018-03-12T08:22:56-07:00
      DOI: 10.1242/jeb.176156
  • The effects of lateral line ablation and regeneration in schooling giant
           danios [RESEARCH ARTICLE]
    • Authors: Mekdara, P. J; Schwalbe, M. A. B, Coughlin, L. L, Tytell, E. D.
      Abstract: Prasong J. Mekdara, Margot. A. B. Schwalbe, Laura L. Coughlin, and Eric D. Tytell

      Fish use multiple sensory systems, including vision and their lateral line system, to maintain position and speed within a school. Although previous studies have shown that ablating the lateral line alters schooling behavior, no one has examined how the behavior recovers as the sensory system regenerates. We studied how schooling behavior changes in giant danios Devario aequipinnatus when their lateral line system is chemically ablated and after the sensory hair cells regenerate. We found that fish could school normally immediately after chemical ablation, but that they had trouble schooling one to two weeks after the chemical treatment, when the hair cells had fully regenerated. We filmed groups of giant danios with two high-speed cameras and reconstructed the 3D positions of each fish within a group. One fish in the school was treated with gentamycin to ablate all hair cells. Both types of neuromasts, canal and superficial, were completely ablated after treatment but fully regenerated after one week. We quantified the structure of the school using nearest neighbor distance, bearing, elevation, and the cross-correlation of velocity between each pair of fish. Treated fish maintained a normal position within the school immediately after the lateral line ablation, but could not school normally one or two weeks after treatment, even though the neuromasts had fully regenerated. By four to eight weeks post-treatment, the treated fish could again school normally. These results demonstrate that the behavioral recovery after lateral line ablation is a longer process than the regeneration of the hair cells themselves.
      PubDate: 2018-03-12T08:22:56-07:00
      DOI: 10.1242/jeb.175166
  • A simple model predicts energetically optimised jumping in dogs [RESEARCH
    • Authors: Daniels, K. A. J; Burn, J. F.
      Abstract: Katherine A. J. Daniels and J. F. Burn

      It is generally accepted that animals move in a way that minimises energy use during regular gait and there is evidence that the principle might extend more generally to locomotor behaviour and manoeuvres. Jumping during locomotion is a useful manoeuvre that contributes to the versatility of legged locomotion and is within the repertoire of many terrestrial animals. We describe a simple ballistic model that can be used to identify a single unique trajectory of the body's centre of mass that minimises the mechanical work to initiate a jump, regardless of the approach velocity or take-off position. The model was used to show that domestic dogs (Canis lupus familiaris) demonstrate complex anticipatory control of locomotor behaviour by systematically using jump trajectories close to those that minimised the mechanical energy of jumps over raised obstacles. It is unclear how the dogs acquired the complex perception and control necessary to exhibit the observed behaviour. The model may be used to investigate whether animals adopt energetically optimised behaviour in any similarly-constrained ballistic task.
      PubDate: 2018-03-12T08:22:56-07:00
      DOI: 10.1242/jeb.167379
  • Critical thermal limits of bumble bees (Bombus impatiens) are marked by
           stereotypical behaviors and are unchanged by acclimation, age, or feeding
           status [RESEARCH ARTICLE]
    • Authors: Oyen, K. J; Dillon, M. E.
      Abstract: K. Jeannet Oyen and Michael E. Dillon

      Critical thermal limits often determine species distributions for diverse ectotherms and have become a useful tool for understanding past and predicting future range shifts in response to changing climates. Despite recently documented population declines and range shifts of bumble bees (genus Bombus), the few measurements of thermal tolerance available for the group have relied on disparate measurement approaches. We describe a novel stereotypical behavior expressed by bumble bee individuals during entry into chill coma. This behavioral indicator of CTmin occurred at ambient temperatures of 3-5 °C (~7-9 °C core temperatures) and was accompanied by a pronounced CO2 pulse, indicative of loss of spiracle function. CTmax was indicated by the onset of muscular spasms prior to entering an unresponsive state and occurred at ambient temperatures of ~52-55 °C (42-44 °C core temperatures). Measurements of CTmin and CTmax were largely unaffected by acclimation, age, or feeding status, but faster ramping rates significantly increased CTmax and decreased CTmin. This high-throughput approach allows rapid measurement of critical thermal limits for large numbers of bees, facilitating large-scale comparisons among bumble bee populations and species – a key step in determining current and future effects of climate on these critical pollinators.
      PubDate: 2018-03-12T08:22:56-07:00
      DOI: 10.1242/jeb.165589
  • Photoreceptor specialization and the visuomotor repertoire of the
           primitive chordate Ciona [RESEARCH ARTICLE]
    • Authors: Salas, P; Vinaithirthan, V, Newman-Smith, E, Kourakis, M. J, Smith, W. C.
      Abstract: Priscilla Salas, Vall Vinaithirthan, Erin Newman-Smith, Matthew J. Kourakis, and William C. Smith

      The swimming tadpole larva of Ciona has one of the simplest central nervous systems known, with only 177 neurons. Despite its simplicity, the Ciona CNS shares common structure with the CNS of its close chordate relatives, the vertebrates. The recent completion of a larval Ciona CNS connectome creates enormous potential for detailed understanding of chordate CNS function, yet our understanding of Ciona larval behavior is incomplete. We show here that Ciona larvae have a surprisingly rich and dynamic set of visual responses, including a looming-object escape behavior characterized by erratic circular swims, as well as negative phototaxis characterized by sustained directional swims. Making use of mutant lines, we show that these two behaviors are mediated by distinct groups of photoreceptors. The Ciona connectome predicts that these two behavioral responses should act through distinct, but overlapping, visuomotor pathways, and that the escape behavior is likely to be integrated into a broader startle behavior.
      PubDate: 2018-03-06T02:47:31-08:00
      DOI: 10.1242/jeb.177972
  • Conserved spatio-temporal patterns of suction-feeding flows across aquatic
           vertebrates: a comparative flow visualization study [RESEARCH ARTICLE]
    • Authors: Jacobs, C; Holzman, R.
      Abstract: Corrine Jacobs and Roi Holzman

      Suction feeding is a widespread prey capture strategy among aquatic vertebrates. It is almost omnipresent across fishes, and has repeatedly evolved in other aquatic vertebrates. By rapidly expanding the mouth cavity, suction-feeders generate a fluid flow outside of their mouth, drawing prey inside. Fish and other suction feeding organisms display remarkable trophic diversity, echoed in the diversity of their skull and mouth morphologies. Yet, it is unclear how variable suction flows are across species, and whether variation in suction flows supports trophic diversity. Using a high-speed flow visualization technique, we characterized the spatio-temporal patterns in the flow fields produced during feeding in 14 species of aquatic suction feeders. We found that suction-feeding hydrodynamics are highly conserved across species. Suction flows affected only a limited volume of ~1 gape diameter away from the mouth, and peaked around the timing of maximal mouth opening. The magnitude of flow speed increased with increasing mouth diameter and, to a lesser extent, with decreasing time to peak gape opening. Other morphological, kinematic and behavioral variables played a minor role in shaping suction-feeding dynamics. We conclude that the trophic diversity within fishes, and likely other aquatic vertebrates, is not supported by a diversity of mechanisms that modify the characteristics of suction flow. Rather, we suggest that suction feeding supports such trophic diversity due to the general lack of strong trade-offs with other mechanisms that contribute to prey capture.
      PubDate: 2018-03-06T02:47:31-08:00
      DOI: 10.1242/jeb.174912
  • Emersion behaviour underlies variation in gill morphology and aquatic
           respiratory function in the amphibious fish Kryptolebias marmoratus
    • Authors: Turko, A. J; Tatarenkov, A, Currie, S, Earley, R. L, Platek, A, Taylor, D. S, Wright, P. A.
      Abstract: A. J. Turko, A. Tatarenkov, S. Currie, R. L. Earley, A. Platek, D. S. Taylor, and P. A. Wright

      Fishes acclimated to hypoxic environments often increase gill surface area to improve O2 uptake. In some species, surface area is increased via reduction of an interlamellar cell mass (ILCM) that fills water channels between gill lamellae. Amphibious fishes, however, may not increase gill surface area in hypoxic water because these species can instead leave water and breathe air. To differentiate between these possibilities, we compared wild amphibious mangrove rivulus Kryptolebias marmoratus from two habitats that varied in O2 availability – a hypoxic freshwater pool versus nearly anoxic crab burrows. Fish captured from crab burrows had less gill surface area, as ILCMs were enlarged by ~32%, increased rates of normoxic O2 consumption, and increased critical O2 tension compared to fish from the freshwater pool. Thus, wild mangrove rivulus do not respond to near-anoxic water by decreasing metabolism or increasing O2 extraction. Instead, fish from the crab burrow habitat spent 3-fold more time out of water, which probably caused the observed changes in gill morphology and respiratory phenotype. We also tested whether critical O2 tension is influenced by genetic heterozygosity, as K. marmoratus is one of only two hermaphroditic vertebrate species that can produce both self-fertilized (inbred) or out-crossed (more heterozygous) offspring. We found no evidence for inbreeding depression, suggesting that self-fertilization does not impair respiratory function. Overall, our results demonstrate that amphibious fishes that inhabit hypoxic aquatic habitats can use a fundamentally different strategy than fully aquatic water-breathing fishes, relying on escape behaviour rather than metabolic depression or increased O2 extraction ability.
      PubDate: 2018-03-06T02:47:31-08:00
      DOI: 10.1242/jeb.168039
  • Anti-diuretic action of a CAPA neuropeptide against a subset of diuretic
           hormones in the disease vector, Aedes aegypti. [RESEARCH ARTICLE]
    • Authors: Sajadi, F; Curcuruto, C, Al Dhaheri, A, Paluzzi, J.-P. V.
      Abstract: Farwa Sajadi, Carmela Curcuruto, Afra Al Dhaheri, and Jean-Paul V. Paluzzi

      The mosquito, Aedes aegypti, is a vector responsible for transmitting various pathogens to humans, and their prominence as chief vectors of human disease is largely due to their anthropophilic blood feeding behaviour. Larval stage mosquitoes must deal with the potential dilution of their haemolymph in fresh water, whereas the haematophagus A. aegypti female faces the challenge of excess ion and water intake after a blood meal. The excretory system, comprised of the Malpighian tubules (MTs) and hindgut, is strictly controlled by neuroendocrine factors, responsible for the control of diuresis across all developmental stages. The highly-studied insect MTs are influenced by a variety of diuretic hormones, and in some insects, anti-diuretic factors. In the present study, we investigated the effects of AedaeCAPA-1 on larval and adult female A. aegypti MTs stimulated with various diuretic factors including serotonin (5-HT), a corticotropin-related factor (CRF) diuretic peptide, a calcitonin-related diuretic hormone (DH31), and a kinin-related diuretic peptide. Overall, our findings establish that AedaeCAPA-1 specifically inhibits secretion of larval and adult MTs stimulated by 5-HT and DH31, whilst having no activity on MTs stimulated by other diuretic factors. Furthermore, although AedaeCAPA-1 acts as an anti-diuretic, it does not influence the relative proportions of cations transported by adult MTs, thus maintaining the kaliuretic activity of 5-HT and natriuretic activity of DH31. In addition, we tested the effects of the second messenger cGMP in adult MTs. Here, we established that cGMP displays similar effects as AedaeCAPA-1, strongly inhibiting 5-HT and DH31-stimulated fluid secretion, but with only minor effects on CRF-stimulated diuresis. Interestingly, although AedaeCAPA-1 has no inhibitory activity on kinin-stimulated fluid secretion, cGMP strongly inhibited fluid secretion by this diuretic hormone, which targets stellate cells specifically. Collectively, these results support that AedaeCAPA-1 inhibits select diuretic factors acting on the principal cells and this likely involves cGMP as a second messenger. Kinin-stimulated diuresis, which targets stellate cells, is also inhibited by cGMP suggesting that another anti-diuretic factor in addition to AedaeCAPA-1 exists and may utilize cGMP as a second messenger.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.177089
  • Brain mitochondrial bioenergetics change with rapid and prolonged shifts
           in aggression in the honey bee, Apis mellifera [RESEARCH ARTICLE]
    • Authors: Rittschof, C. C; Vekaria, H. J, Palmer, J. H, Sullivan, P. G.
      Abstract: Clare C. Rittschof, Hemendra J. Vekaria, Joseph H. Palmer, and Patrick G. Sullivan

      Neuronal function demands high-level energy production, and as such, a decline in mitochondrial respiration characterizes brain injury and disease. A growing number of studies, however, link brain mitochondrial function to behavioral modulation in non-diseased contexts. In the honey bee, we show for the first time that an acute social interaction, which invokes an aggressive response, may also cause a rapid decline in brain mitochondrial bioenergetics. The degree and speed of this decline has only been previously observed in the context of brain injury. Furthermore, in the honey bee, age-related increases in aggressive tendency are associated with increased baseline brain mitochondrial respiration, as well as increased plasticity in response to metabolic fuel type in vitro. Similarly, diet restriction and ketone body feeding, which commonly enhance mammalian brain mitochondrial function in vivo, cause increased aggression. Thus, even in normal behavioral contexts, brain mitochondria show a surprising degree of variation in function over both rapid and prolonged timescales, with age predicting both baseline function and plasticity in function. These results suggest that mitochondrial function is integral to modulating aggression-related neuronal signaling. We hypothesize that variation in function reflects mitochondrial calcium buffering activity, and that shifts in mitochondrial function signal to the neuronal soma to regulate gene expression and neural energetic state. Modulating brain energetic state is emerging as a critical component of the regulation of behavior in non-diseased contexts.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.176917
  • Suppression of reactive oxygen species generation in heart mitochondria
           from anoxic turtles: the role of complex I S-nitrosation [RESEARCH
    • Authors: Bundgaard, A; James, A. M, Joyce, W, Murphy, M. P, Fago, A.
      Abstract: Amanda Bundgaard, Andrew M. James, William Joyce, Michael P. Murphy, and Angela Fago

      Freshwater turtles (Trachemys scripta) are among the very few vertebrates capable of tolerating severe hypoxia and reoxygenation without suffering from damage to the heart. As myocardial ischemia and reperfusion causes a burst of mitochondrial reactive oxygen species (ROS) in mammals, the question arises as to whether, and if so how, this ROS burst is prevented in the turtle heart. We find here that heart mitochondria isolated from turtles acclimated to anoxia produce less ROS than mitochondria from normoxic turtles when consuming succinate. As succinate accumulates in the hypoxic heart and is oxidised when oxygen returns this suggest an adaptation to lessen ROS production. Specific S-nitrosation of complex I can lower ROS in mammals and here we show that turtle complex I activity and ROS production can also be strongly depressed in vitro by S-nitrosation. While we can detect in vivo endogenous S-nitrosated complex I in turtle heart mitochondria, these levels are unaffected upon anoxia acclimation. Thus while heart mitochondria from anoxia-acclimated turtles generate less ROS and have a lower aerobic capacity than those from normoxic turtles, this is not due to decreases in complex I activity or expression levels. Interestingly, in-gel activity staining reveals that most complex I of heart mitochondria from normoxic and anoxic turtles forms stable supercomplexes with other respiratory enzymes and, in contrast to mammals, these are not disrupted by dodecyl maltoside. Taken together, these results show that, although S-nitrosation of complex I is a potent mechanism to prevent ROS formation upon reoxygenation after anoxia in vitro, this is not a major cause of the suppression of ROS production by anoxic turtle heart mitochondria.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.174391
  • Food consumption increases cell proliferation in the python brain [Short
    • Authors: Habroun, S. S; Schaffner, A. A, Taylor, E. N, Strand, C. R.
      Abstract: Stacy S. Habroun, Andrew A. Schaffner, Emily N. Taylor, and Christine R. Strand

      Pythons are model organisms for investigating physiological responses to food intake. While systemic growth in response to food consumption is well documented, what occurs in the brain is currently unexplored. In this study, male ball pythons (Python regius) were used to test the hypothesis that food consumption stimulates cell proliferation in the brain. We used 5-bromo-12’-deoxyuridine as a cell-birth marker to quantify and compare cell proliferation in the brain of fasted snakes and those at two and six days after a meal. Throughout the telencephalon, cell proliferation was significantly increased in the six-day group, with no difference between the two-day group and controls. Systemic postprandial plasticity occurs quickly after a meal is ingested, during the period of active digestion; however, the brain displays a surge of cell proliferation after most digestion and absorption is complete.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.173377
  • Thermal analysis of ice and glass transitions in insects that do and do
           not survive freezing [RESEARCH ARTICLE]
    • Authors: Rozsypal, J; Moos, M, Simek, P, Kostal, V.
      Abstract: Jan Rozsypal, Martin Moos, Petr Simek, and Vladimir Kostal

      Some insects rely on the strategy of freeze tolerance for winter survival. During freezing, extracellular body water transitions from the liquid to solid phase and cells undergo freeze-induced dehydration. Here we present results of a thermal analysis (from differential scanning calorimetry) of ice fraction dynamics during gradual cooling after inoculative freezing in variously acclimated larvae of two drosophilid flies, Drosophila melanogaster and Chymomyza costata. Although the species and variants ranged broadly between 0 and close to 100% survival of freezing, there were relatively small differences in ice fraction dynamics. For instance, the maximum ice fraction (IFmax) ranged between 67.9 and 77.7% total body water (TBW). The C. costata larvae showed statistically significant phenotypic shifts in parameters of ice fraction dynamics (melting point and IFmax) upon entry into diapause, cold-acclimation, and feeding on a proline-augmented diet. These differences were mostly driven by colligative effects of accumulated proline (ranging between 6 and 487–1 TBW) and other metabolites. Our data suggest that these colligative effects per se do not represent a sufficient mechanistic explanation for high freeze tolerance observed in diapausing, cold-acclimated C. costata larvae. Instead, we hypothesize that accumulated proline exerts its protective role via a combination of mechanisms. Specifically, we found a tight association between proline-induced stimulation of glass transition in partially-frozen body liquids (vitrification) and survival of cryopreservation in liquid nitrogen.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.170464
  • Fight, fatigue, and flight: narrowing of attention to a threat compensates
           for decreased anti-predator vigilance [RESEARCH ARTICLE]
    • Authors: Ota K.
      Abstract: Kazutaka Ota

      Fighting carries predation risk because animals have limited attention, constraining their ability to simultaneously engage in aggression and anti-predator vigilance. However, the influence of interspecific aggression and fatigue on the predation cost of fighting is seldom examined, although both are unignorable aspects of fighting. Here, I incorporated both factors in a series of field experiments on the cichlid Lamprologus ocellatus. If territorial males respond more strongly to conspecific territorial intruders than heterospecific intruders, then they should delay escape more frequently during intraspecific fighting than interspecific fighting. Consequently, although I predict that vigilance would be decreased as fighting progresses in both fighting, intraspecific aggression should decrease vigilance more than interspecific aggression. Males were also exposed to a predator approaching at different (slow or fast) speeds during these fighting bouts. Delays in predator detection and flight initiation were quantified and these predictions were tested. As predicted, males were responded more strongly to intraspecific intruders, resulting in slower predator detection and fleeing times than when encountering interspecific intruders. Furthermore, flight latency decreased with increasing fight duration, suggesting that fatigue negatively influenced escape responses. However, contrary to prediction, the vigilance decrement rate was faster in response to slow predators than to rapid predators, and was not influenced by intruder identity. This suggests that fighting males reserve their attention for information critical to their survival and are less vigilant toward a less-threatening (slow approaching) predator. This cognitive allocation may be an adaptive compensation for fatigue-related low vigilance during fighting.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.168047
  • Effects of long-term sucrose overfeeding on rat brown adipose tissue: a
           structural and immunohistochemical study [RESEARCH ARTICLE]
    • Authors: Velickovic, K. D; Ukropina, M. M, Glisic, R. M, Cakic-Milosevic, M. M.
      Abstract: Ksenija D. Velickovic, Mirela M. Ukropina, Radmila M. Glisic, and Maja M. Cakic-Milosevic

      The aim of this study was to determine the effects of long-term sucrose overfeeding on functional capacity and ultrastructural characteristics of the rat brown adipose tissue (BAT). For the study, sixteen male Wistar rats, chow-fed and kept under standard laboratory conditions were divided into 2 equal groups. The rats from a control group drank tap water, while those from a sucrose overfed group were allowed to drink 10% sucrose solution for 21 days. Structural changes of BAT were analysed at the level of light and electron microscopy on routinely prepared tissue sections or using immunohistochemical staining, in combination with stereological methods. Obtained results have shown that significantly increased energy intake in sucrose overfed rats did not result in elevated body mass gain. The light microscopy analysis revealed that the BAT acquired the appearance of a thermogenically active tissue, with intensified vascularisation, reduced size of brown adipocytes and increased multilocularity. At the ultrastructural level, mitochondria of brown adipocytes became more abundant, enlarged, and contained more cristae in comparison to control animals. The immunoexpression of uncoupling protein 1 (UCP1) and noradrenaline, as markers of BAT thermogenic status was increased, while the pattern of PGC1α was slightly modified. Taken together, the results of this investigation indicated that BAT possesses the ability to increase thermogenic capacity/activity in response to high energy intake and to prevent body mass gain. These findings are particularly relevant in the view of recent reports on the existence of functional BAT in adult humans and its potential use to combat obesity.
      PubDate: 2018-03-01T06:23:21-08:00
      DOI: 10.1242/jeb.166538
  • The effect of air resistance on the jump performance of a small parasitoid
           wasp, Anagyrus pseudococci (Encyrtidae) [RESEARCH ARTICLE]
    • Authors: Urca, T; Ribak, G.
      Abstract: Tomer Urca and Gal Ribak

      The distance a small insect moves through air during a jump is limited by the launch velocity at take-off and by air resistance. The launch velocity is limited by the length of the jumping legs and the maximum power that the jump apparatus can provide for pushing against the ground. The effect of air resistance is determined by the insect mass-to-area ratio. Both limitations are highly dependent on the body size, making high jumps a challenge for smaller insects. We studied both effects in the tiny Encyrtid wasp Anagyrus pseudococci. Males are smaller than females (mean body length 1.2 and 1.8 mm, respectively), but both sexes take-off in a powerful jump. Using high-speed cameras, we analyzed the relationship between take-off kinematics and distance traveled through air. We show that the velocity, acceleration and mass-specific power while leaving the ground places A. pseudococci among the most prominent jumpers of the insect world. However, the absolute distance moved through air is modest compared to other jumping insects, due to air resistance acting on the small body. A biomechanical model suggests that air resistance reduces the jump distance of these insects by 49%, compared to jumping in the absence of air resistance. The effect of air resistance is more pronounced in the smaller males resulting in a segregation of the jumping performance between sexes. The limiting effect of air resistance is inversely proportional to body mass, seriously constraining jumping as a form of moving through air in these and other small insects.
      PubDate: 2018-02-27T08:20:33-08:00
      DOI: 10.1242/jeb.177600
  • High activity before breeding improves reproductive performance by
           enhancing mitochondrial function and biogenesis [RESEARCH ARTICLE]
    • Authors: Zhang, Y; Brasher, A. L, Park, N. R, Taylor, H. A, Kavazis, A. N, Hood, W. R.
      Abstract: Yufeng Zhang, Adam L. Brasher, Noel R. Park, Halie A. Taylor, Andreas N. Kavazis, and Wendy R. Hood

      Understanding of physiological responses of organisms is typically based on data collected during an isolated event. Although many fundamental insights have been gained from these studies, evaluating the response to a single event ignores the fact that each individual has experienced a unique set of events throughout its life that may have altered its physiology. The idea that prior experiences can influence subsequent performance is known as a carry-over effect. Carry-over effects may explain much of the variation in performance found among individuals. For example, high physical activity has been shown to improve mitochondrial respiratory function and biogenesis and reduce oxidative stress and has been linked to improved health and longevity. In this study, we asked if the bioenergetic differences between active and inactive individuals carry over to impact performance in a subsequent reproductive event and alter a females' reproductive outcome. Female mice that had access to running wheel for a month before mating gave birth to a larger litter and weaned a heavier litter, indicating that high physical activity had a positive carry-over effect to reproduction. Mice that ran also displayed higher mitochondria respiration and biogenesis with no changes in endogenous antioxidant enzymes. These results provide a mechanistic framework for how the conditions that animals experience before breeding can impact reproductive outcomes.
      PubDate: 2018-02-27T08:20:33-08:00
      DOI: 10.1242/jeb.177469
  • Molecular and functional characterization of the Gulf toadfish serotonin
           transporter (SERT; SLC6A4) [RESEARCH ARTICLE]
    • Authors: Amador, M. H. B; McDonald, M. D.
      Abstract: Molly H. B. Amador and M. Danielle McDonald

      The serotonin transporter (SERT) functions in the uptake of the neurotransmitter serotonin (5-HT) from the extracellular milieu and is the molecular target of the selective serotonin reuptake inhibitors (SSRIs), a common group of antidepressants. The current study comprehensively assesses the sequence, tissue distribution, transport kinetics, and physiological function of a teleost SERT. The 2,022-bp toadfish SERT sequence encodes a protein of 673 amino acids, which shows 83% similarity to zebrafish SERT and groups with SERT of other teleosts in phylogenetic analysis. SERT mRNA is ubiquitous in tissues and is expressed at high levels in the heart and, within the brain, in the cerebellum. SERT cRNA expressed in Xenopus laevis oocytes demonstrates a Km value of 2.08±0.45 µM, similar to previously reported Km values for zebrafish and human SERT. Acute systemic blockade of SERT by intraperitoneal administration of the SSRI fluoxetine (FLX) produces a dose-dependent increase in plasma 5-HT, indicating effective inhibition of 5-HT uptake from the circulation. As teleosts lack platelets, which are important 5-HT sequestration sites in mammals, the FLX-induced increase in plasma 5-HT suggests that toadfish tissues may normally be responsible for maintaining low 5-HT concentrations in the bloodstream.
      PubDate: 2018-02-27T08:20:33-08:00
      DOI: 10.1242/jeb.170928
  • HSP90 regulates larval settlement of the bryozoan Bugula neritina through
           NO pathway [RESEARCH ARTICLE]
    • Authors: Yang, X.-X; Zhang, Y, Wong, Y.-H, Qian, P.-Y.
      Abstract: Xiao-Xue Yang, Yu Zhang, Yue-Him Wong, and Pei-Yuan Qian

      The larvae of many sessile marine invertebrates go through a settlement process, during which the planktonic larvae attach to a substrate and metamorphose into sessile juveniles. Larval attachment and metamorphosis (herein defined as "settlement") are complex processes mediated by many signaling pathways. Nitric oxide (NO) signaling is one of the pathways that inhibits larval settlement in marine invertebrates across different phyla. NO is synthesized by NO synthase (NOS), which is a client of molecular chaperon heat shock protein 90 (HSP90). In the present study, we provide evidence that NO, a gaseous messenger, regulates larval settlement of B. neritina. By using pharmacological bioassays and western blotting, we demonstrated that NO inhibits larval settlement of B. neritina and that NO signals occur mainly in the sensory organ of swimming larvae. The settlement rate of B. neritina larvae decreased after heat shock treatment. Inhibition of HSP90 induced larval settlement, and attenuated the inhibition of NO donors during larval settlement. In addition, the expression level of both HSP90 and NOS declined upon settlement. These results demonstrate that HSP90 regulates the larval settlement of B. neritina by interacting with the NO pathway.
      PubDate: 2018-02-27T08:20:33-08:00
      DOI: 10.1242/jeb.167478
  • Miniaturisation decreases visual navigational competence in ants [RESEARCH
    • Authors: Palavalli-Nettimi, R; Narendra, A.
      Abstract: Ravindra Palavalli-Nettimi and Ajay Narendra

      Evolution of smaller body size in a given lineage, called miniaturisation, is commonly observed in many animals including ants. It affects various morphological features and is hypothesized to result in inferior behavioural capabilities, possibly owing to smaller sensory organs. To test this hypothesis, we studied whether reduced spatial resolution of compound eyes influences obstacle detection or obstacle avoidance in five different species of ants. We trained all ant species to travel to a sugar feeder. During their return journeys, we placed an obstacle close to the nest entrance. We found that ants with higher spatial resolution exited the corridor, the area covered between either ends of the obstacle, on average 10 cm earlier suggesting they detected the obstacle earlier in their path. Ants with the lowest spatial resolution changed their viewing directions only when they were close to the obstacle. We discuss the effects of miniaturisation on visual navigational competence in ants.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.177238
  • Stress and disease resilience differences related to emergence time for
           first feeding in farmed rainbow trout (Oncorhynchus mykiss) [RESEARCH
    • Authors: Gesto, M; Madsen, L, Andersen, N. R, Jokumsen, A.
      Abstract: Manuel Gesto, Lone Madsen, Nikolaj R. Andersen, and Alfred Jokumsen

      Salmonid individuals show a relatively high variability in the time required to abandon the gravel nest where they hatch, the so-called "emergence time". Different behavioral and physiological traits have been shown to be associated to that emergence time in wild salmonids. In general, early- and late-emerging fish have traits resembling those of proactive and reactive stress coping styles, respectively. Proactive fish are considered to be more resilient to stress and probably to disease, so it was hypothesized that fish with different emergence time have different ability to resist repeated episodes of stress without suffering deleterious effects on their welfare or health status. In this study, rainbow trout eyed eggs were hatched and larvae were fractionated according to their emergence time (Early fraction: first 20 % of fish to emerge; Intermediate fraction: mid 20 %; Late fraction: last 20 %). When the fish were four months old, part of the fish were exposed to a daily repeated stress protocol for 15 days. The next day, both naïve and repeatedly-stressed fish were exposed to an acute stress challenge. Different plasma (cortisol, glucose, lactate) as well as CNS (serotonergic activity) stress markers were assessed to evaluate the stress resilience of the different fractions. Furthermore, an intraperitoneal infection challenge with Flavobacterium psychrophilum was carried out to assess the disease resilience of the different emergence fractions. Altogether, the results showed that fish from different fractions displayed different activation of the hypothalamus-pituitary-interrenal axis, pointing to a higher stress resilience in the fish with shorter emergence times. However, those differences were not reflected in the ability of the different fractions to grow and perform well in terms of growth, or in the ability to overcome the infection with the bacteria, which was similar for all the emergence fractions. This suggests that discriminating fish according to emergence time would probably have little effect in improving the performance and the welfare of farmed fish.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.174623
  • The membrane pacemaker hypothesis: novel tests during the ontogeny of
           endothermy [RESEARCH ARTICLE]
    • Authors: Price, E. R; Sirsat, T. S, Sirsat, S. K. G, Curran, T, Venables, B. J, Dzialowski, E. M.
      Abstract: Edwin R. Price, Tushar S. Sirsat, Sarah K. G. Sirsat, Thomas Curran, Barney J. Venables, and Edward M. Dzialowski

      The ‘membrane pacemaker’ hypothesis proposes a biochemical explanation for among-species variation in resting metabolism, based on the positive correlation between membrane docosahexaenoic acid (DHA) and metabolic rate. We tested this hypothesis using a novel model, altricial red-winged blackbird nestlings, predicting that the proportion of DHA in muscle and liver membranes should increase with the increasing metabolic rate of the nestling as it develops endothermy. We also used a dietary manipulation, supplementing the natural diet with fish oil (high DHA) or sunflower oil (high linoleic acid) to alter membrane composition and then assessed metabolic rate. In support of the membrane pacemaker hypothesis, DHA proportions increased in membranes from pectoralis muscle, muscle mitochondria, and liver during post-hatch development. By contrast, elevated dietary DHA had no effect on resting metabolic rate, despite causing significant changes to membrane lipid composition. During cold challenges, higher metabolic rates were achieved by birds that had lower DHA and higher linoleic acid in membrane phospholipids. Given the mixed support for this hypothesis, we conclude that correlations between membrane DHA and metabolic rate are likely spurious, and should be attributed to a still-unidentified confounding variable.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.174466
  • Acid-base regulation in the air-breathing swamp eel (Monopterus albus) at
           different temperatures [RESEARCH ARTICLE]
    • Authors: Thinh, P. V; Phuong, N. T, Brauner, C. J, Huong, D. T. T, Wood, A. T, Kwan, G. T, Conner, J. L, Bayley, M, Wang, T.
      Abstract: Phan Vinh Thinh, Nguyen Thanh Phuong, Colin J. Brauner, Do Thi Thanh Huong, Andrew T. Wood, Garfield T. Kwan, Justin L. Conner, Mark Bayley, and Tobias Wang

      Vertebrates reduce arterial blood pH (pHa) when body temperature increases. In water-breathers this response occurs primarily by reducing plasma HCO3– levels with small changes in the partial pressure of CO2 (PCO2). In contrast, air-breathers mediate the decrease in pHa by increasing arterial PCO2 (PaCO2) at constant plasma HCO3– by reducing lung ventilation relative to metabolic CO2 production. Much less is known in bimodal breathers that utilize both water and air. Here, we characterize the influence of temperature on arterial acid-base balance and intracellular pH (pHi) in the bimodal breathing swamp eel, Monopterus albus. This teleost uses the buccopharyngeal cavity for gas exchange and has very reduced gills. When exposed to ecologically relevant temperatures (20, 25, 30 and 35°C) for 24 and 48h, pHa decreased by -0.025 pH units/°C (U/°C) in association with an increased PaCO2, but without changes in plasma [HCO3–]. Intracellular pH (pHi) was also reduced with increased temperature. The slope of pHi of liver and muscle was -0.014 and -0.019 U/°C, while the heart muscle showed a smaller reduction (-0.008U/°C). When exposed to hypercapnia (7 or 14 mmHg) at either 25 or 35°C, Monopterus albus elevated plasma [HCO3–] and therefore seemed to defend the new pHa set-point, demonstrating an adjusted control of acid-base balance with temperature. Overall, the effects of temperature on acid-base balance in Monopterus albus resemble air-breathing amniotes, and we discuss the possibility that this pattern of acid-base balance results from a progressive transition in CO2 excretion from water to air as temperature rises.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.172551
  • Emptying and refilling of slime glands in Atlantic (Myxine glutinosa) and
           Pacific (Eptatretus stoutii) hagfishes [RESEARCH ARTICLE]
    • Authors: Schorno, S; Gillis, T. E, Fudge, D. S.
      Abstract: Sarah Schorno, Todd E. Gillis, and Douglas S. Fudge

      Hagfishes are known for their unique defensive slime, which they use to ward off gill breathing predators. While much is known about the slime cells (gland thread cells and gland mucous cells), little is known about how long slime gland refilling takes, or how slime composition changes with refilling or repeated stimulation of the same gland. Slime glands can be individually electro-stimulated to release slime, and this technique was used to measure slime gland refilling times for Atlantic and Pacific hagfish. The amount of exudate produced, the composition of exudate, and the morphometrics of slime cells were analyzed during refilling, and as a function of stimulation number when full glands were stimulated in rapid succession. Complete refilling of slime glands for both species took three to four weeks, with Pacific hagfish achieving faster absolute rates exudate recovery than Atlantics. We found significant changes in composition of exudate and morphometrics of slime cells from Pacific hagfish during refilling. Over successive stimulations of full Pacific glands, multiple boluses of exudate were released, with exudate composition, but not thread cell morphometrics, changing significantly. Finally, histological examination of slime glands revealed slime cells retained in glands after exhaustion. Discrepancies in volume of cells released that can be explained by contraction of striated muscle alone suggests other mechanisms may be involved in the exudate ejection. Our results provide a first look at the process and timing of slime gland refilling in hagfishes, and raise new questions about how refilling is achieved at the cellular level.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.172254
  • Detection and direction discrimination of single vortex rings by harbour
           seals (Phoca vitulina) [RESEARCH ARTICLE]
    • Authors: Krüger, Y; Hanke, W, Miersch, L, Dehnhardt, G.
      Abstract: Yvonne Krüger, Wolf Hanke, Lars Miersch, and Guido Dehnhardt

      Harbour seals possess highly sensitive vibrissae that enable them to track hydrodynamic trails left behind by a swimming fish. Most of these trails contain vortex rings as a main hydrodynamic component. They may reveal information about their generator as the trails differ depending on the fish species, the fish's body shape, size, and swimming style. Additionally, fish generate single vortex rings in diverse natural situations. In this study, the ability of blindfolded stationary harbour seals to detect and analyse single vortex rings regarding directional information has been investigated. In three different behavioural experiments, the animals were trained to respond to single artificially generated vortex rings. The results show that harbour seals are able to respond to a variety of different vortex rings upon vibrissal stimulation. The investigation of the minimum hydrodynamically perceivable angle revealed that it is at least as small as 5.7°, which was the smallest adjustable angle. Moreover, harbour seals are capable of analysing the travel direction of a vortex ring perceived by the mystacial pads irrespective of whether the vibrissae were stimulated ipsilaterally or contralaterally. In situations in which no complex hydrodynamic trail is available, it is advantageous for a hunting seal to be able to extract information from a single vortex ring.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.170753
  • Three-dimensional analysis of the fast-start escape response of the least
           killifish, Heterandria formosa [RESEARCH ARTICLE]
    • Authors: Fleuren, M; van Leeuwen, J. L, Quicazan-Rubio, E. M, Pieters, R. P. M, Pollux, B. J. A, Voesenek, C. J.
      Abstract: Mike Fleuren, Johan L. van Leeuwen, Elsa M. Quicazan-Rubio, Remco P. M. Pieters, Bart J. A. Pollux, and Cees J. Voesenek

      Fish make C-starts to evade predator strikes. Double-bend (DB) C-starts consist of three stages: Stage 1, in which the fish rapidly bends into a C-shape; Stage 2, in which the fish bends in the opposite direction; and a variable Stage 3. In single-bend (SB) C-starts, the fish immediately straightens after Stage 1. Despite fish moving in 3D space, fast-start responses of adult fish have mainly been studied in a horizontal plane. Using automated 3D tracking of multi-camera high-speed video sequences, we show that both SB and DB fast-starts by adult female least killifish (Heterandria formosa) often contain a significant vertical velocity component, and large changes in pitch (DB: up to 43 deg) and roll (DB: up to 77 deg) angles. Upwards and downwards elevation changes are correlated with changes in pitch angle of the head; movement in the horizontal plane is correlated with changes in yaw angle of the head. With respect to the stimulus, escape heading correlates with the elevation of the fish at the onset of motion. Irrespective of the initial orientation, fish can escape in any horizontal direction. In many cases, the centre of mass barely accelerates during Stage 1. However, it does accelerate in the final direction of the escape in other instances, indicating that Stage 1 can serve a propulsive role in addition to its preparatory role for Stage 2. Our findings highlight the importance of large-scale 3D analyses of fast-start manoeuvres of adult fish in uncovering the versatility of fish escape repertoire.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.168609
  • Kinematics of swimming of the manta ray: three-dimensional analysis of
           open water maneuverability [RESEARCH ARTICLE]
    • Authors: Fish, F. E; Kolpas, A, Crossett, A, Dudas, M. A, Moored, K. W, Bart-Smith, H.
      Abstract: Frank E. Fish, Allison Kolpas, Andrew Crossett, Michael A. Dudas, Keith W. Moored, and Hilary Bart-Smith

      For aquatic animals, turning maneuvers represent a locomotor activity that may not be confined to a single coordinate plane, making analysis difficult particularly in the field. To measure turning performance in a three-dimensional space for the manta ray (Mobula birostris), a large open-water swimmer, scaled stereo video recordings were collected. Movements of the cephalic lobes, eye and tail base were tracked to obtain three-dimensional coordinates. A mathematical analysis was performed on the coordinate data to calculate the turning rate and curvature (1/turning radius) as a function of time by numerically estimating the derivative of manta trajectories through three-dimensional space. Principal component analysis (PCA) was used to project the three-dimensional trajectory onto the two-dimensional turn. Smoothing splines were applied to these turns. These are flexible models that minimize a cost function with a parameter controlling the balance between data fidelity and regularity of the derivative. Data for 30 sequences of rays performing slow, steady turns showed the highest 20% of values for the turning rate and smallest 20% of turn radii were 42.65±16.66 deg s–1 and 2.05±1.26 m, respectively. Such turning maneuvers fall within the range of performance exhibited by swimmers with rigid bodies.
      PubDate: 2018-02-27T08:20:32-08:00
      DOI: 10.1242/jeb.166041
  • The stomatogastric nervous system of the medicinal leech: its anatomy,
           physiology and associated aminergic neurons [RESEARCH ARTICLE]
    • Authors: Mesce, K. A; Alania, M, Gaudry, Q, Puhl, J. G.
      Abstract: Karen A. Mesce, Magda Alania, Quentin Gaudry, and Joshua G. Puhl

      Blood feeding is an essential and signature activity of the medicinal leech species, Hirudo verbana. Despite keen interest in understanding the neuronal substrates of this behavior, a major component of the nervous system associated with feeding has remained overlooked. In this study, for the first time, we report on the presence and characteristics of five stomatogastic ganglia (STGs) comprising the visceral stomatogastric nervous system (STN) of the leech. Although Hanke (1948) provided a brief report that a ring of three ganglia (not five) was associated with the cephalic ganglia, this information was never integrated into subsequent neurobiological studies of feeding. Here, the anatomical features of the STGs are described as are the morphological and electrophysiological characteristics of neurons originating in them. We also determined that two of the five STGs (STG-1 and STG-3) each contained two relatively large (ca. 40 µm diameter) serotonergic neurons. The STN was also richly invested by dopaminergic and serotonergic arborizations, however, no intrinsic dopaminergic somata were observed. The trajectory of the serotonergic LL neuron, a command-like cell for feeding, was documented to project directly to the STN and not to the jaw and pharyngeal musculature as previously reported, thus reopening the important question of how the LL cell activates and coordinates biting activity with pharyngeal swallowing. Additional studies revealed that the LL cell is excited by blood serum applied to the lip and is strongly inhibited by dopamine. These findings provide a new foundation for understanding the regulation and modulation of feeding neural networks.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.175687
  • Antibacterial activity of male and female sperm-storage organs in ants
    • Authors: Davila, F; Botteaux, A, Bauman, D, Cherasse, S, Aron, S.
      Abstract: Francisco Davila, Anne Botteaux, David Bauman, Sarah Cherasse, and Serge Aron

      Bacteria can damage sperm and thus reduce the reproductive success of both males and females; selection should therefore favour the evolution of antimicrobial protection. Eusocial hymenopterans might be particularly affected by such bacterial infections because of their mating ecology. In both sexes, mating is restricted to a short window early in the adult stage; there are no further chances to mate later in life. Males die shortly after mating, but queens use the acquired sperm to fertilise their eggs for years, sometimes decades. The reproductive success of both sexes is, thus, ultimately sperm-limited, which maintains strong selection for high sperm viability before and after storage. We tested the antibacterial activity of the contents of the male and female sperm-storage organs—the accessory testes and the spermatheca, respectively. As our study species, we used the bacterium Escherichia coli and the garden ant Lasius niger whose queens can live for several decades. Our results provide the first empirical evidence that male and female sperm-storage organs display different antibacterial activity. While the contents of the accessory testes actually enhanced bacterial growth, the contents of the spermatheca strongly inhibited it. Furthermore, mating appears to activate the general immune system in queens. However, antimicrobial activity in both the spermatheca and the control tissue (head-thorax homogenate) declined rapidly post mating, consistent with a trade-off between immunity and reproduction. Overall, this study suggests that ejaculates undergo an immune ‘flush’ at the time of mating, allowing storage of sperm cells free of bacteria.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.175158
  • Testing the parasite mass burden effect on host behaviour alteration in
           the Schistocephalus-stickleback system [SHORT COMMUNICATION]
    • Authors: Grecias, L; Valentin, J, Aubin-Horth, N.
      Abstract: Lucie Grecias, Julie Valentin, and Nadia Aubin-Horth

      Many parasites with complex life cycles modify their intermediate host's behaviour, which has been proposed to increase transmission to their definitive host. This behavioural change could result from the parasite actively manipulating its host, but could also be explained by a mechanical effect, where the parasite's physical presence affects host behaviour. We created an artificial internal parasite using silicone injections in the body cavity to test this mechanical effect hypothesis. We used the Schistocephalus solidus - threespine stickleback (Gasterosteus aculeatus) system, as this cestode can reach up to 92% of its fish host mass. Our results suggest that the mass burden brought by this macroparasite alone is not sufficient to cause behavioural changes in its host. Furthermore, our results show that wall-hugging (thigmotaxis), a measure of anxiety in vertebrates, is significantly reduced in Schistocephalus-infected sticklebacks, unveiling a new altered component of behaviour that may result from manipulation by this macroparasite.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.174748
  • Differential immune-gene expression in sperm storage organs of
           leaf-cutting ants [RESEARCH ARTICLE]
    • Authors: Cherasse, S; Baer, B, Schiott, M, Boomsma, J. J.
      Abstract: Sarah Cherasse, Boris Baer, Morten Schiott, and Jacobus J. Boomsma

      Leaf-cutting ant queens mate with multiple males during a single nuptial flight and store sperm for up to two decades. During mating, males transfer sperm from their accessory testes to the queen bursa copulatrix from where it enters the spermatheca, an insect sperm storage organ that has become highly specialised in long-lived ant queens who never re-mate later in life. Long-term storage without the possibility to obtain new sperm creates an immune defence dilemma, because recognition of non-self cells eliminates infections but may also target irreplaceable sperm and reduce lifetime reproductive success. We therefore hypothesised that non-specific immune responses, like pathogen melanisation, should be silenced in the spermatheca, because they rely on general non-self recognition, but that specific responses such as antimicrobial peptides are activated instead because they specifically target pathogenic bacteria and/or fungi. The maintenance of uninfected sperm cells by males before mating is not constrained by non-self recognition meaning immune regulation might be more liberal in male reproductive organs. To test this hypothesis, we measured gene expression of two antimicrobial peptides, abaecin and defensin, and prophenoloxidase, an important enzyme of the melanisation pathway, in male accessory glands and testes and in queen bursae copulatrix and spermathecae of Acromyrmex echinatior and Atta colombica leaf-cutting ants. As expected, prophenoloxidase expression was low in reproductive organs that sustain prolonged contact with sperm whereas antimicrobial peptides showed average to high expression, indicating that leaf-cutting ants invest in specific rather than generalist immune defences for pathogen protection in organs that store sperm.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.173435
  • Measuring metabolic rates of small terrestrial organisms by
    • Authors: Tomlinson, S; Dalziell, E. L, Withers, P. C, Lewandrowski, W, Dixon, K. W, Merritt, D. J.
      Abstract: Sean Tomlinson, Emma L. Dalziell, Philip C. Withers, Wolfgang Lewandrowski, Kingsley W. Dixon, and David J. Merritt

      We explore a recent innovative variation of closed-system respirometry for terrestrial organisms, whereby pO2 is repeatedly measured fluorometrically in a constant-volume chamber over multiple time points. We outline a protocol that aligns this technology with the broader literature on aerial respirometry, including the calculations required to accurately convert O2 depletion to metabolic rate (MR). We identify a series of assumptions, and sources of error associated with this technique, including thresholds where O2 depletion becomes limiting, that impart errors to the calculation and interpretation of MR. Using these adjusted calculations, we found that the resting MR of five species of angiosperm seeds ranged from 0.011 to 0.640 mL.g–1.h–1, consistent with published seed MR. This innovative methodology greatly expands the lower size limit of terrestrial organisms that can be measured, and offers the potential for measuring MR changes over time as a result of physiological processes of the organism.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.172874
  • Intestinal {alpha} -glycosidase transcriptional responses during
           development and diet adjustment in altricial birds [SHORT COMMUNICATION]
    • Authors: Gatica-Sosa, C; Brzek, P, Magallanes, M, Karasov, W. H, Caviedes-Vidal, E.
      Abstract: Claudia Gatica-Sosa, Pawel Brzek, Melisa Magallanes, William H. Karasov, and Enrique Caviedes-Vidal

      We describe developmental changes in maltasic activity and its mRNA through adulthood, and in response to increase in dietary starch. We studied house sparrows (HOSP; Passer domesticus L.), which undergo a natural switch from insects to starch-containing seed diet during development, and zebra finch (ZEBF; Taeniopygia guttata V.), which have a relatively fixed starchy-seed diet during development. In ZEBF, in whom maltasic activity increased with age but not with dietary starch, α –glycosidase (AG) mRNA was not affected by either age or dietary starch level. In HOSP nestlings, in whom maltasic activity increased with age and with added starch, AG mRNA was higher on diet with added starch but did not increase with age. These results are consistent with the idea that the apparent programmed developmental increase in maltasic activity is not mainly under transcriptional control of AG mRNA, whereas induction of maltasic activity by increased dietary starch is.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.171827
  • Enzyme polymorphism, oxygen and injury: a lipidomic analysis of
           flight-induced oxidative damage in a SDH-polymorphic insect [RESEARCH
    • Authors: Pekny, J. E; Smith, P. B, Marden, J. H.
      Abstract: Julianne E. Pekny, Philip B. Smith, and James H. Marden

      When active tissues receive insufficient oxygen to meet metabolic demand, succinate accumulates and has two fundamental effects: it causes ischemia-reperfusion injury while also activating the hypoxia-inducible factor pathway (HIF). The Glanville fritillary butterfly (Melitaea cinxia) possesses a balanced polymorphism in Sdhd, shown previously to affect HIF pathway activation and tracheal morphology and used here to experimentally test the hypothesis that variation in succinate dehydrogenase affects oxidative injury. We stimulated butterflies to fly continuously in a respirometer (3 min duration), which typically caused episodes of exhaustion and recovery, suggesting a potential for cellular injury from hypoxia and reoxygenation in flight muscles. Indeed, flight muscle from butterflies flown on consecutive days had lipidomic profiles similar to rested paraquat-injected butterflies, but distinct from rested untreated butterflies. Many butterflies showed a decline in flight metabolic rate (FMR) on Day 2, and there was a strong inverse relationship between the ratio of Day 2 to Day 1 FMR and the abundance of sodiated adducts of phosphatidylcholines and coenzyme Q (CoQ). This result is consistent with elevation of sodiated lipids caused by disrupted intracellular ion homeostasis in mammalian tissues after hypoxia-reperfusion. Butterflies carrying the Sdhd M allele had higher abundance of lipid markers of cellular damage, but the association was reversed in field-collected butterflies, where focal individuals typically flew for seconds at a time rather than continuously. These results indicate that Glanville fritillary flight muscles can be injured by episodes of high exertion, but injury severity appears to be determined by an interaction between SDH genotype and behavior (prolonged vs. intermittent flight).
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.171009
  • Task-specific sensory coding strategies are matched to detection and
           discrimination performance [RESEARCH ARTICLE]
    • Authors: Allen, K. M; Marsat, G.
      Abstract: K. M. Allen and G. Marsat

      The acquisition of sensory information is limited by the neural encoding method used, constraining perceptual abilities. The most relevant aspects of stimuli may change as behavioral context changes, making efficient encoding of information more challenging. Sensory systems must balance rapid detection of a stimulus with perception of fine details that enable discrimination between similar stimuli. We show that in a species of weakly electric fish, Apteronotus leptorhynchus, two coding strategies are employed for these separate behavioral tasks. Using communication signals, we demonstrate a strong correlation between neural coding strategies and behavioral performance on a discrimination task. Extracellular recordings of pyramidal cells within the electrosensory lateral line lobe of alert fish show two distinct response patterns, either burst discharges with little variation between different signals of the same category, or a graded, heterogeneous response that contains sufficient information to discriminate between signals with slight variations. When faced with a discrimination-based task, the behavioral performance of the fish closely matches predictions based on coding strategy. Comparisons of these results with neural and behavioral responses observed in other model systems suggest that our study highlights a general principle in the way sensory systems utilize different neural codes.
      PubDate: 2018-02-14T06:36:26-08:00
      DOI: 10.1242/jeb.170563
  • Avian thermoregulation in the heat: evaporative cooling capacity and
           thermal tolerance in two Australian parrots [RESEARCH ARTICLE]
    • Authors: McWhorter, T. J; Gerson, A. R, Talbot, W. A, Smith, E. K, McKechnie, A. E, Wolf, B. O.
      Abstract: Todd J. McWhorter, Alexander R. Gerson, William A. Talbot, Eric Krabbe Smith, Andrew E. McKechnie, and Blair O. Wolf

      Avian orders differ in their thermoregulatory capabilities and tolerance of high environmental temperatures. Evaporative heat loss, and the primary avenue whereby it occurs, differs amongst taxa. Although Australian parrots (Psittaciformes) have been impacted by mass mortality events associated with extreme weather events (heat waves), their thermoregulatory physiology has not been well-characterized. We quantified the upper limits to thermoregulation under extremely hot conditions in two Australian parrots: the mulga parrot (Psephotellus varius; ~55 g) and the galah (Eolophus roseicapilla; ~265 g). At air temperatures (Ta) exceeding body temperature (Tb), both species showed increases in Tb to maximum values around 43–44°C, accompanied by rapid increases in resting metabolic rate above clearly defined upper critical limits of thermoneutrality and increases in evaporative water loss (EWL) to levels equivalent to 700–1000% of baseline rates at thermoneutral Ta.Maximum cooling capacity, quantified as the fraction of metabolic heat production dissipated evaporatively, ranged from 1.71 to 1.79, consistent with the known range for parrots, similar to the corresponding range in passerines, and well below the corresponding ranges for columbids and caprimulgids. Heat tolerance limit (HTL, the maximum Ta tolerated) ranged from 44-55°C, similar to the range reported for passerines, but lower than reported for columbids and caprimulgids. Our data suggest that heat tolerance in parrots is similar to that of passerines. We argue that understanding how thermoregulatory capacity and heat tolerance vary across avian orders is vital for predicting how climate change and the associated increase in frequency of extreme weather events may impact avian populations in the future.
      PubDate: 2018-02-13T09:13:48-08:00
      DOI: 10.1242/jeb.168930
  • Environmental calcium and variation in yolk sac size influence swimming
           performance in larval lake sturgeon (Acipenser fulvescens) [RESEARCH
    • Authors: Deslauriers, D; Svendsen, J. C, Genz, J, Wall, A. J, Baktoft, H, Enders, E. C, Anderson, W. G.
      Abstract: David Deslauriers, Jon C. Svendsen, Janet Genz, Alex J. Wall, Henrik Baktoft, Eva C. Enders, and W. Gary Anderson

      In many animal species, performance in the early life stages strongly affects recruitment to the adult population; however, factors that influence early life history stages are often the least understood. This is particularly relevant for lake sturgeon, Acipenser fulvescens, living in areas where environmental calcium concentrations are declining, partly due to anthropogenic activity. As calcium is important for muscle contraction and fatigue resistance, declining calcium levels could constrain swimming performance. Similarly, swimming performance could be influenced by variation in yolk sac volume, because the yolk sac is likely to affect drag forces during swimming. Testing swimming performance of larval A. fulvescens reared in four different calcium treatments spanning the range of 4-132 mg l–1 [Ca2+], this study found no treatment effects on the sprint swimming speed. A novel test of volitional swimming performance, however, revealed reduced swimming performance in the low calcium environment. Specifically, volitionally swimming larvae covered a shorter distance before swimming cessation in the low calcium environment compared to the other treatments. Moreover, sprint swimming speed in larvae with a large yolk sac was significantly slower than in larvae with a small yolk sac, regardless of body length variation. Thus, elevated maternal allocation (i.e., more yolk) was associated with reduced swimming performance. Data suggest that larvae in low calcium environments or with a large yolk sac exhibit reduced swimming performance and could be more susceptible to predation or premature downstream drift. Our study reveals how environmental factors and phenotypic variation influence locomotor performance in a larval fish.
      PubDate: 2018-02-13T09:13:48-08:00
      DOI: 10.1242/jeb.164533
  • Biomechanics of omnidirectional strikes in flat spiders [RESEARCH ARTICLE]
    • Authors: Zeng, Y; Crews, S.
      Abstract: Yu Zeng and Sarah Crews

      Many ambush predators attack prey using rapid strikes, but these strikes are typically only anteriorly directed. However, a predator may attack laterally- and posteriorly-oriented prey if it can couple the strikes with rapid body reorientation. Here, we examined omnidirectional strikes in flattie spiders (Selenopidae), a group of sit-and-wait ambush predators found on open surfaces. These spiders attack prey throughout their entire peripheral range using rapid strikes that consist of rapid translation and rotation toward the prey. These spiders ambush with radially oriented, long, laterigrade legs in a ready-to-fire status. Once prey is detected, the spider maneuvers toward prey using a single flexion of the legs closest to the prey, which is assisted by 0–3 extension strides by contralateral legs. The within-stance joint actions by a few legs generate a large resultant force pointing to the prey and a large turning moment. Furthermore, the turning speed is enhanced by rapid midair leg adductions, which effectively reduce the spiders’ moment of inertia during angular acceleration. Our results demonstrate a novel hunting behavior with high maneuverability that is generated with effectively controlled reconfigurations of long, laterigrade legs. These results provide insights for understanding the diversity of animal legs and developing highly maneuverable multi-legged robots.
      PubDate: 2018-02-12T04:45:14-08:00
      DOI: 10.1242/jeb.166512
  • Distinct physiological, biochemical and morphometric adjustments in the
           malaria vectors Anopheles gambiae and An. coluzzii as means to survive to
           dry season conditions in Burkina Faso [RESEARCH ARTICLE]
    • Authors: Hidalgo, K; Montazeau, C, Siaussat, D, Braman, V, Trabalon, M, Simard, F, Renault, D, Mouline, K.
      Abstract: K. Hidalgo, C. Montazeau, D. Siaussat, V. Braman, M. Trabalon, F. Simard, D. Renault, and K. Mouline

      Aestivation and dispersive migration are the two strategies evoked in literature to explain the way by which malaria vectors, Anopheles coluzzii and An. gambiae, survive the harsh climatic conditions of the dry season in sub-Saharan Africa. However, the physiological mechanisms regulating these two strategies are unknown. Here, mosquito species were submitted to controlled environmental parameters mimicking the rainy and dry seasons conditions of south-western Burkina Faso. Survival strategies were studied through morphometric (wing length), ecophysiological (respiratory gas exchanges), biochemical (cuticular hydrocarbons composition) and molecular (AKH mRNA expression levels) parameters of which variations are classically considered as hallmarks of aestivation and dispersion mechanisms in various insects. Our results showed that ecophysiological and morphometric adjustments are put in place in both species to prevent water losses during the dry season. However, the classical metabolic rate modifications expected as signatures of aestivation and migration were not evidenced here, highlighting specific and original physiological mechanisms sustaining survival in malaria mosquitoes during the dry season. Differences in epicuticular hydrocarbons composition and AKH levels of expression were found between the permanent and temporary An. coluzzii populations, illustrating the great phenotypic plasticity of this mosquito species. Altogether, our work underlines the diverse and complex pattern of changes occurring in the two mosquito species and at the population level to cope with the dry season and highlights potential targets of future control tools.
      PubDate: 2018-01-29T05:32:44-08:00
      DOI: 10.1242/jeb.174433
  • Vibration-guided mate searching in treehoppers: directional accuracy and
           sampling strategies in a complex sensory environment [RESEARCH ARTICLE]
    • Authors: Gibson, J. S; Cocroft, R. B.
      Abstract: Jeremy S. Gibson and Reginald B. Cocroft

      Animal movement decisions involve an action-perception cycle in which sensory flow influences motor output. Key aspects of the action-perception cycle involved in movement decisions can be identified by integrating path information with measurement of environmental cues. We studied mate searching in insects for which the primary sensory cues are mechanical vibrations traveling through the tissues of living plants. We mapped search paths of male thornbug treehoppers locating stationary females through an exchange of vibrational signals. At each of the males’ sampling locations, we used two-dimensional laser vibrometry to measure stem motion produced by female vibrational signals. We related properties of the vibrational signals to the males’ movement direction, inter-sample distance, and accuracy. Males experienced gradients in signal amplitude and in the whirling motion of the plant stem, and these gradients were influenced to varying degrees by source distance and local stem properties. Males changed their sampling behavior during the search, making longer inter-sample movements farther from the source where uncertainty is higher. The primary directional cue used by searching males was the direction of wave propagation, and males made more accurate decisions when signal amplitude was higher, when time delays were longer between front and back legs, and when female responses were short in duration. The whirling motion of plant stems, including both the eccentricity and the major axes of motion, is a fundamental feature of vibrational environments on living plants, and we show for the first time that it has important influences on the decisions of vibrationally-homing insects.
      PubDate: 2018-01-24T05:00:41-08:00
      DOI: 10.1242/jeb.175083
  • Renoguanylin stimulates apical CFTR translocation and decreases HCO3-
           secretion through PKA activity in the Gulf toadfish (Opsanus beta)
    • Authors: Ruhr, I. M; Schauer, K. L, Takei, Y, Grosell, M.
      Abstract: Ilan M. Ruhr, Kevin L. Schauer, Yoshio Takei, and Martin Grosell

      The guanylin peptides – guanylin, uroguanylin, and renoguanylin (RGN) – are endogenously produced hormones in teleost fish enterocytes that are activators of guanylyl cyclase-C (GC-C) and are potent modulators of intestinal physiology, particularly in seawater teleosts. Most notably, they reverse normal net ion-absorbing mechanisms that are vital to water absorption, an important process for seawater teleost survival. The role of guanylin-peptide stimulation of the intestine remains unclear, but it is hypothesized to facilitate the removal of solids from the intestine by providing fluid to enable their removal by peristalsis. The present study uses one member of these peptides – RGN – to provide evidence for the prominent role that protein kinase A (PKA) plays in mediating the effects of guanylin-peptide stimulation in the posterior intestine of the Gulf toadfish (Opsanus beta). Protein kinase G is shown to not mediate the intracellular effects of RGN, despite previous evidence showing that GC-C activation leads to higher cyclic guanosine monophosphate formation. RGN is shown to reverse the absorptive short-circuit current and increase conductance in the Gulf toadfish intestine. These effects are correlated to increased trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl– channel to the apical membrane, which are negated by PKA inhibition. Moreover, RGN decreases HCO3– secretion, likely by limiting the exchange activity of SLC26a6 (a HCO3–/Cl– antiporter), a reduction that is enhanced by PKA inhibition. RGN seems to alter PKA activity in the posterior intestine to recruit CFTR to the apical membrane and reduce HCO3– secretion.
      PubDate: 2018-01-22T03:50:28-08:00
      DOI: 10.1242/jeb.173948
  • Ammonia excretion and acid-base regulation in the American horseshoe crab,
           Limulus polyphemus [RESEARCH ARTICLE]
    • Authors: Hans, S; Quijada-Rodriguez, A. R, Allen, G. J. P, Onken, H, Treberg, J. R, Weihrauch, D.
      Abstract: Stephanie Hans, Alex R. Quijada-Rodriguez, Garett J. P. Allen, Horst Onken, Jason R. Treberg, and Dirk Weihrauch

      Many studies have investigated ammonia excretion and acid-base regulation in aquatic arthropods, yet current knowledge of marine chelicerates is non-existent. In American horseshoe crabs (Limulus polyphemus), book gills bear physiologically distinct regions: dorsal and ventral half-lamellae, and central mitochondria-rich (CMRA) and peripheral mitochondria-poor areas (PMPA). CMRA and ventral half-lamella exhibited characteristics important to ammonia excretion and/or acid-base regulation as supported by high expression levels of Rhesus-protein 1 (LpRh-1), cytoplasmic carbonic anhydrase (CA-2), and hyperpolarization-activated cyclic nucleotide-gated K+ channel (HCN) compared to PMPA and dorsal half-lamella. The half-lamellae displayed remarkable differences; the ventral epithelium was ion-leaky whilst the dorsal counterpart possessed an exceptionally tight epithelium. LpRh-1 was more abundant than LpRh-2 in all investigated tissues, but LpRh-2 was more prevalent in the PMPA than CMRA. Ammonia influx associated with high ambient ammonia (HAA) treatment was counteracted by intact animals and complemented by upregulation of branchial CA-2, V-type H+-ATPase (HAT), HCN, and LpRh-1 mRNA expression. The dorsal epithelium demonstrated characteristics of active ammonia excretion, however, an influx was observed across the ventral epithelium due to the tissue's high ion conductance, although the influx rate was not proportionately high considering the ~3-fold inwardly-directed ammonia gradient. Novel findings suggest a role for the coxal gland in excretion and maintaining hemolymph ammonia regulation under HAA. Hypercapnic exposure induced compensatory respiratory acidosis and partial metabolic depression. Functional differences between 2 halves of a branchial lamella may be physiologically beneficial in reducing backflow of waste products into adjacent lamellae, especially in fluctuating environments where ammonia levels can increase.
      PubDate: 2018-01-18T07:51:26-08:00
      DOI: 10.1242/jeb.151894
  • Sleep deprivation negatively impacts reproductive output in Drosophila
           melanogaster [RESEARCH ARTICLE]
    • Authors: Potdar, S; Daniel, D. K, Thomas, F. A, Lall, S, Sheeba, V.
      Abstract: Sheetal Potdar, Danita K. Daniel, Femi A. Thomas, Shraddha Lall, and Vasu Sheeba

      Most animals sleep or exhibit a sleep-like state, yet the adaptive significance of this phenomenon remains unclear. Although reproductive deficits are associated with lifestyle induced sleep deficiencies, how sleep loss affects reproductive physiology is poorly understood, even in model organisms. We aimed to bridge this mechanistic gap by impairing sleep in female fruit flies and testing its effect on egg output. We find that sleep deprivation by feeding caffeine or by mechanical perturbation results in decreased egg output. Transient activation of wake-promoting dopaminergic neurons decreases egg output in addition to sleep levels, thus demonstrating a direct negative impact of sleep deficit on reproductive output. Similarly, loss-of-function mutation in dopamine transporter fumin (fmn) leads to both significant sleep loss and lowered fecundity. This demonstration of a direct relationship between sleep and reproductive fitness indicates a strong driving force for the evolution of sleep.
      PubDate: 2018-01-04T06:44:29-08:00
      DOI: 10.1242/jeb.174771
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