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BIOCHEMISTRY (215 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 8)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Chemical Biology     Full-text available via subscription   (Followers: 232)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 11)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 7)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 9)
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Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 8)
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Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 11)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 7)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 121)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Polymer Science     Open Access   (Followers: 21)
Amino Acids     Hybrid Journal   (Followers: 6)
Analytical Biochemistry     Hybrid Journal   (Followers: 123)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 35)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 20)
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Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 10)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access   (Followers: 2)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 3)
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Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
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Biochemistry     Full-text available via subscription   (Followers: 198)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 1)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 11)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 5)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 6)
Biochimie     Hybrid Journal   (Followers: 5)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 14)
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BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
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BioMolecular Concepts     Hybrid Journal   (Followers: 2)
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Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 22)
BMC Biochemistry     Open Access   (Followers: 12)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 3)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 6)
ChemBioChem     Hybrid Journal   (Followers: 3)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 22)
Chemical Engineering Journal     Hybrid Journal   (Followers: 24)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 2)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 18)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 4)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 10)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 3)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)

        1 2 3     

Journal Cover   Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [3 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2801 journals]
  • The potential impacts of migratory difficulty, including warmer waters and
           altered flow conditions, on the reproductive success of salmonid fishes
    • Abstract: Publication date: Available online 18 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Miriam Fenkes, Holly A. Shiels, John L. Fitzpatrick, Robert L. Nudds
      Climate change and urbanisation of watercourses affect water temperatures and current flow velocities in river systems on a global scale. This represents a particularly critical issue for migratory fish species with complex life histories that use rivers to reproduce. Salmonids are migratory keystone species that provide substantial economical value to ecosystems and human societies. Consequently, a comprehensive understanding of the effects of environmental stressors on their reproductive success is critical in order to ensure their continued abundance during future climatic change. Salmonids are capital breeders, relying entirely on endogenous energy stores to fuel return migration to their natal spawning sites and reproduction upon arrival. Metabolic rates and cost of transport en-route increase with temperature and at extreme temperatures, swimming is increasingly fuelled anaerobically, resulting in an oxygen debt and reduced capacity to recover from exhaustive exercise. Thermally challenged salmonids also produce less viable gametes, which themselves are affected by water temperature after release. Passage through hydrological barriers and temperature changes both affect energy expenditure. As a result, important energetic trade-offs emerge between extra energy used during migration and that available for other facets of the reproductive cycle, such as reproductive competition and gamete production. However, studies identifying these trade-offs are extremely sparse. This review focuses on the specific locomotor responses of salmonids to thermal and hydrological challenges, identifying gaps in our knowledge and highlighting the potential implications for key aspects of their reproduction.

      PubDate: 2015-11-21T03:35:32Z
  • Seasonal variation in baseline and maximum whole-body glucocorticoid
           concentrations in a small-bodied stream fish independent of habitat
    • Abstract: Publication date: February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 192
      Author(s): Cassia B. Belanger, Marilyn N. Vera-Chang, Thomas W. Moon, Jonathan D. Midwood, Cory D. Suski, Steven J. Cooke
      Alterations to natural habitats are becoming more common due to changes in anthropogenic land use. As such, there is increasing interest in determining how wild animals adapt and respond to environmental stressors. The glucocorticoid (GC) stress response enables animals to react appropriately to environmental challenges but can be affected by many factors, two of which are habitat quality and time of year (i.e., season). This study tested whether baseline and maximum (stress-induced) whole-body cortisol concentrations varied in relation to habitat quality and season using wild central mudminnows (Umbra limi) collected from two connected streams differing in habitat quality in each of four seasons. Overall, baseline and maximum cortisol levels did not differ significantly between the two systems but there was evidence of a seasonal effect. Baseline cortisol levels in the fall and summer were significantly (P <0.01) lower than those in winter and spring and maximum cortisol levels in the summer were significantly lower (P <0.01) than those in the spring. Inconsistent with the prevailing paradigm, our results indicate that habitat quality does not always influence baseline GCs or the stress response. In contrast, baseline and maximum GCs in this species do vary seasonally. As such, seasonality should be considered in the interpretation of stress response data especially when using small-bodied stream fish as biological indicators.

      PubDate: 2015-11-21T03:35:32Z
  • Salinity Effects on Plasma Ion Levels, Cortisol, and Osmolality in Chinook
           salmon Following Lethal Sampling
    • Abstract: Publication date: Available online 18 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Heather A. Stewart, David L.G. Noakes, Karen M. Cogliati, James T. Peterson, Martin H. Iversen, Carl B. Schreck
      Studies on hydromineral balance in fishes frequently employ measurements of electrolytes following euthanasia. We tested the effects of fresh- or salt- water euthanasia baths of tricaine mesylate (MS-222) on plasma magnesium (Mg2+) and sodium (Na+) ions, cortisol and osmolality in fish exposed to saltwater challenges, and the ion and steroid hormone fluctuations over time following euthanasia in juvenile spring Chinook salmon (Oncorhynchus tshawytscha). Salinity of the euthanasia bath affected plasma Mg2+ and Na+ concentrations as well as osmolality, with higher concentrations in fish euthanized in saltwater. Time spent in the bath positively affected plasma Mg2+ and osmolality, negatively affected cortisol, and had no effect on Na+ concentrations. The difference of temporal trends in plasma Mg2+ and Na+ suggests that Mg2+ may be more sensitive to physiological changes and responds more rapidly than Na+. When electrolytes and cortisol are measured as endpoints after euthanasia, care needs to be taken relative to time after death and the salinity of the euthanasia bath.

      PubDate: 2015-11-21T03:35:32Z
  • Impact of different temperatures on survival and energy metabolism in the
           Asian citrus psyllid, Diaphorina citri Kuwayama
    • Abstract: Publication date: Available online 18 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ibrahim El-Shesheny, Faraj Hijaz, Ibrahim El-Hawary, Ibrahim Mesbah, Nabil Killiny
      Temperature influences the life history and metabolics parameters of insects. Asian citrus psyllid (ACP), Diaphorina citri is a tropical and subtropical pest. ACP invaded new regions around the world and threatened the citrus industry as a vector for Huanglongbing (HLB) disease. ACP is widely distributed and can survive high (up to 45°C) and low temperatures (as low as -6 °C). The precise mechanism of temperature tolerance in ACP is poorly understood. We investigated adult survival, cellular energy balance, gene expression, and nucleotides and sugar-nucleotides changes under the effect of different temperature regimes (0 °C to 45 °C with 5 °C intervals). The optimum temperatures for survival were 20 and 25 °C. Low temperatures of 0 °C and 5 °C caused 50% mortality after 2 and 4 days respectively, while one day at high temperature (40 °C and 45 °C) caused more than 95% mortality. The lowest quantity of ATP (3.69±1.6 ng/insect) and the maximum ATPase enzyme activities (57.43±7.6 μU/insect) were observed at 25 °C. Correlation between ATP quantities and ATPase activity was negative. Gene expression of hsp70, V-type proton ATPase catalytic subunit A and ATP synthase α subunit matched these results. Twenty-four nucleotides and sugar-nucleotides were quantified using HPLC in ACP adults maintained at low, high, and optimum temperatures. The nucleotide profiles were different among treatments. The ratios between AMP:ATP and ADP:ATP were significantly decreased and positively correlated to adults survival, whereas the adenylate energy charge was increased in response to low and high temperatures. Exploring energy metabolic regulation in relation with adult survival might help in understanding the physiological basis of how ACP tolerates newly invaded regions.

      PubDate: 2015-11-21T03:35:32Z
  • Effects of wintertime fasting and seasonal adaptation on AMPK and ACC in
           hypothalamus, adipose tissue and liver of the raccoon dog (Nyctereutes
    • Abstract: Publication date: Available online 18 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sanni Kinnunen, Satu Mänttäri, Karl-Heinz Herzig, Petteri Nieminen, Anne-Mari Mustonen, Seppo Saarela
      The raccoon dog (Nyctereutes procyonoides) is a canid with autumnal fattening and passive wintering strategy. We examined the effects of wintertime fasting and seasonality on AMP-activated protein kinase (AMPK), a regulator of metabolism, and its target, acetyl-CoA carboxylase (ACC) on the species. Twelve farmed raccoon dogs (eleven females/one male) were divided into two groups: half were fasted for ten weeks in December–March (winter fasted) and the others were fed ad libitum (winter fed). A third group (autumn fed, eight females) was fed ad libitum and sampled in December. Total AMPK, ACC and their phosphorylated forms (pAMPK, pACC) were measured from hypothalamus, liver, intra-abdominal (iWAT) and subcutaneous white adipose tissues (sWAT). The fasted animals lost 32% and the fed 20% of their body mass. Hypothalamic AMPK expression was lower and pACC levels higher in the winter groups compared to the autumn fed group. Liver pAMPK was lower in the winter fasted group, with consistently decreased ACC and pACC. AMPK and pAMPK were down-regulated in sWAT and iWAT of both winter groups, with a parallel decline in pACC in sWAT. The responses of AMPK and ACC to fasting were dissimilar to the effects observed previously in non-seasonal mammals and also hibernators. Differences between the winter fed and autumn fed groups indicate that the functions of AMPK and ACC could be regulated in a season-dependent manner. Furthermore, the distinctive effects of prolonged fasting and seasonal adaptation on AMPK–ACC pathway could contribute to the wintering strategy of the raccoon dog.

      PubDate: 2015-11-21T03:35:32Z
  • Purine metabolism in response to hypoxic conditions associated with
           breath-hold diving and exercise in erythrocytes and plasma from bottlenose
           dolphins (Tursiops truncatus)
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Iris del Castillo Velasco-Martínez, Claudia J. Hernández-Camacho, Lía C. Méndez-Rodríguez, Tania Zenteno-Savín
      In mammalian tissues under hypoxic conditions, ATP degradation results in accumulation of purine metabolites. During exercise, muscle energetic demand increases and oxygen consumption can exceed its supply. During breath-hold diving, oxygen supply is reduced and, although oxygen utilization is regulated by bradycardia (low heart rate) and peripheral vasoconstriction, tissues with low blood flow (ischemia) may become hypoxic. The goal of this study was to evaluate potential differences in the circulating levels of purine metabolism components between diving and exercise in bottlenose dolphins (Tursiops truncatus). Blood samples were taken from captive dolphins following a swimming routine (n=8) and after a 2min dive (n=8). Activity of enzymes involved in purine metabolism (hypoxanthine guanine phosphoribosyl transferase (HGPRT), inosine monophosphate deshydrogenase (IMPDH), xanthine oxidase (XO), purine nucleoside phosphorylase (PNP)), and purine metabolite (hypoxanthine (HX), xanthine (X), uric acid (UA), inosine monophosphate (IMP), inosine, nicotinamide adenine dinucleotide (NAD+), adenosine, adenosine monophosphate (AMP), adenosine diphosphate (ADP), ATP, guanosine diphosphate (GDP), guanosine triphosphate (GTP)) concentrations were quantified in erythrocyte and plasma samples. Enzymatic activity and purine metabolite concentrations involved in purine synthesis and degradation, were not significantly different between diving and exercise. Plasma adenosine concentration was higher after diving than exercise (p=0.03); this may be related to dive-induced ischemia. In erythrocytes, HGPRT activity was higher after diving than exercise (p=0.007), suggesting an increased capacity for purine recycling and ATP synthesis from IMP in ischemic tissues of bottlenose dolphins during diving. Purine recycling and physiological adaptations may maintain the ATP concentrations in bottlenose dolphins after diving and exercise.

      PubDate: 2015-11-13T03:12:29Z
  • Molecular cloning and characterization of Siamese crocodile (Crocodylus
           siamensis) copper, zinc superoxide dismutase (CSI-Cu,Zn-SOD) gene
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Penporn Sujiwattanarat, Parinya Pongsanarakul, Yosapong Temsiripong, Theeranan Temsiripong, Charin Thawornkuno, Yoshinobu Uno, Sasimanas Unajak, Yoichi Matsuda, Kiattawee Choowongkomon, Kornsorn Srikulnath
      Superoxide dismutase (SOD, EC is an antioxidant enzyme found in all living cells. It regulates oxidative stress by breaking down superoxide radicals to oxygen and hydrogen peroxide. A gene coding for Cu,Zn-SOD was cloned and characterized from Siamese crocodile (Crocodylus siamensis; CSI). The full-length expressed sequence tag (EST) of this Cu,Zn-SOD gene (designated as CSI-Cu,Zn-SOD) contained 462bp encoding a protein of 154 amino acids without signal peptides, indicated as intracellular CSI-Cu,Zn-SOD. This agreed with the results from the phylogenetic tree, which indicated that CSI-Cu,Zn-SOD belonged to the intracellular Cu,Zn-SOD. Chromosomal location determined that the CSI-Cu,Zn-SOD was localized to the proximal region of the Siamese crocodile chromosome 1p. Several highly conserved motifs, two conserved signature sequences (GFHVHEFGDNT and GNAGGRLACGVI), and conserved amino acid residues for binding copper and zinc (His47, His49, His64, His72, His81, Asp84, and His120) were also identified in CSI-Cu,Zn-SOD. Real-time PCR analysis showed that CSI-Cu,Zn-SOD mRNA was expressed in all the tissues examined (liver, pancreas, lung, kidney, heart, and whole blood), which suggests a constitutively expressed gene in these tissues. Expression of the gene in Escherichia coli cells followed by purification yielded a recombinant CSI-Cu,Zn-SOD, with Km and Vmax values of 6.075mM xanthine and 1.4×10−3 mmolmin−1 mg−1, respectively. This Vmax value was 40 times lower than native Cu,Zn-SOD (56×10−3 mmolmin−1 mg−1), extracted from crocodile erythrocytes. This suggests that cofactors, protein folding properties, or post-translational modifications were lost during the protein purification process, leading to a reduction in the rate of enzyme activity in bacterial expression of CSI-Cu,Zn-SOD.

      PubDate: 2015-11-13T03:12:29Z
  • Circulatory changes associated with the closure of the ductus arteriosus
           in hatching emu (Dromaius novaehollandiae)
    • Abstract: Publication date: Available online 5 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lauren Castilla, Warren Burggren, David Muirhead, Thomas C. Nelson, Edward M. Dzialowski
      In developing avian embryos, the right and left ductus arteriosi (DA) allow for a shunt of systemic venous return away from the lungs to the body and chorioallantoic membrane (CAM). Unlike in mammals where the transition from placental respiration to lung respiration is instantaneous, in birds the transition from embryonic CAM respiration to lung respiration can take over 24h. To understand the physiological consequences of this long transition we examined changes and DA morphological changes during hatching in the emu (Dromaius novaehollandiae), a primitive ratite bird. By tracking microspheres injected into a CAM vein, we observed no change in DA blood flow between the pre-pipped to internally pipped stages. Two hours after external pipping, however, a significant decrease in DA blood flow occurred, evident from a decreased systemic blood flow and subsequent increased lung blood flow. Upon hatching, the right-to-left shunt disappeared. These physiological changes in DA blood flow correspond with a large decrease in DA lumen diameter from the pre-pipped stages to Day 1 hatchlings. Upon hatching, the right-to-left shunt disappeared and, at the same time apoptosis of smooth muscle cells began remodeling the DA for permanent closure. After the initial smooth muscle contraction, the lumen disappeared as intimal cushioning formed, the internal elastic lamina degenerated, and numerous cells underwent regulated apoptosis. The DA closed rapidly between the initiation of external pipping and hatching, resulting in circulatory patterns similar to the adult. This response is most likely produced by increased DA constriction in response to increased arterial oxygen levels and the initiation of vessel remodeling.

      PubDate: 2015-11-09T15:41:53Z
  • A comparative study of the response to repeated chasing stress in Atlantic
           salmon (Salmo salar L.) parr and post-smolts
    • Abstract: Publication date: Available online 7 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Angelico Madaro, Rolf Erik Olsen, Tore S. Kristiansen, Lars O.E. Ebbesson, Gert Flik, Marnix Gorissen
      When Atlantic salmon parr migrate from fresh water towards the sea, they undergo extensive morphological, neural, physiological and behavioural changes. Such changes have the potential to affect their responsiveness to various environmental factors that impose stress. In this study we compared the stress responses in parr and post-smolt salmon following exposure to repeated chasing stress (RCS) for three weeks. At the end of this period, all fish were challenged with a novel stressor and sampled before (T0) and after 1h (T1). Parr had a higher growth rate than post-smolts. Plasma cortisol declined in the RCS groups within the first week suggesting a rapid habituation/desensitisation of the endocrine stress axis. As a result of the desensitised HPI axis, RCS groups showed a reduced cortisol response when exposed to the novel stressor. In preoptic area (POA) crf mRNA levels were higher in all post-smolt groups compared to parr. 11βhsd2 decreased by RCS and by the novel stressor in post-smolt controls (T1), whereas no effect of either stress was seen in parr. The grs were low in all groups except for parr controls. In pituitary, parr controls had higher levels of crf1r mRNA than the other parr and post-smolt groups, whilst pomcb was higher in post-smolt control groups. Overall, 11βhsd2 transcript abundance in parr was lower than post-smolt groups; after the novel stressor pomcs, grs and mr were up-regulated in parr control (T1). In summary, we highlight differences in the central stress response between parr and post-smolt salmon following RCS.

      PubDate: 2015-11-09T15:41:53Z
  • Corrigendum to “The digestive morphophysiology of wild, free-living,
           giraffes” [Comp. Biochem. Physiol., A 187 (2015) 119–129]
    • Abstract: Publication date: Available online 3 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): G. Mitchell, D.G. Roberts, S.J. van Sittert

      PubDate: 2015-11-05T15:39:42Z
  • Sexual dimorphism in baseline urinary corticosterone metabolites and their
           association with body-condition indices in a peri-urban population of the
           common Asian toad (Duttaphrynus melanostictus)
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Edward J. Narayan, Narahari P. Gramapurohit
      Field endocrinology research through the quantification of glucocorticoids or stress hormones in free-living wildlife is crucial for assessing their physiological responses towards pervasive environmental changes. Urinary corticosterone metabolite (UCM) enzyme–immunoassay (EIA) has been validated for numerous amphibian species as a non-invasive measure of physiological stress. Body-condition indices (BCIs) have also been widely used in amphibians as an indirect measure of animal health. Field endocrinology research on amphibian species in Asia is limited. In this study, we validated a UCM EIA in a peri-urban sub-population of the common Asian toad (Duttaphrynus melanostictus) in Pune, Maharashtra, India. We determined the baseline levels of UCMs in male (n=39) and female (n=19) toads. Secondly, we used a standard capture handling protocol to quantify changes in UCMs during short-term captivity. We also determined BCIs in the male and female toads using Fulton's index (K) and residual condition index (RCI). The results showed that mean baseline levels of UCMs were significantly higher in male toads than in females. There was no significant change in mean levels of UCMs of males and females between capture and captivity (0–12h). This highlights plausible habituation of the species to the peri-urban environment. Associations between UCMs with BCIs (K and R) were positive in male toads but negative in females. In conclusion, our UCMs EIA can be applied with BCIs to assess health of the Asian toads. We also suggest that direct fitness parameters such as sperm and oocyte quality, reproductive ecology and immunocompetence measurements should be applied in combination with these conservation physiology tools to quantify the fitness consequences of pervasive environmental changes on native amphibians.

      PubDate: 2015-11-01T10:20:18Z
  • Validation of the flooding dose technique to determine fractional rates of
           protein synthesis in a model bivalve species, the blue mussel (Mytilus
           edulis L.)
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Ian D. McCarthy, Ruth Nicholls, Shelagh K. Malham, Nia M. Whiteley
      For the first time, use of the flooding dose technique using 3H-Phenylalanine is validated for measuring whole-animal and tissue-specific rates of protein synthesis in the blue mussel Mytilus edulis (61mm shell length; 4.0g fresh body mass). Following injection, the phenylalanine-specific radioactivities in the gill, mantle and whole-animal free pools were elevated within one hour and remained elevated and stable for up to 6h following injection of 3H-phenylalanine into the posterior adductor muscle. Incorporation of 3H-phenylalanine into body protein was linear over time following injection and the non-significant intercepts for the regressions suggested incorporation into body protein occurred rapidly after injection. These results validate the technique for measuring rates of protein synthesis in mussels. There were no differences in the calculated rates following 1–6h incubation in gill, mantle or whole-animal and fractional rates of protein synthesis from the combined time course data were 9.5±0.8%d−1 for the gill, 2.5±0.3%d−1 for the mantle and 2.6±0.3%d−1 for the whole-animal, respectively (mean values±SEM). The whole-animal absolute rate of protein synthesis was calculated as 18.9±0.6mg protein day−1. The use of this technique in measuring one of the major components of maintenance metabolism and growth will provide a valuable and convenient tool in furthering our understanding of the protein metabolism and energetics of this keystone marine invertebrate and its ability to adjust and respond to fluctuations, such as that expected as a result of climate change.

      PubDate: 2015-11-01T10:20:18Z
  • Metabolic rate, evaporative water loss and thermoregulatory state in four
           species of bats in the Negev desert
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Agustí Muñoz-Garcia, Paloma Larraín, Miriam Ben-Hamo, Ariovaldo Cruz-Neto, Joseph B. Williams, Berry Pinshow, Carmi Korine
      Life in deserts is challenging for bats because of their relatively high energy and water requirements; nevertheless bats thrive in desert environments. We postulated that bats from desert environments have lower metabolic rates (MR) and total evaporative water loss (TEWL) than their mesic counterparts. To test this idea, we measured MR and TEWL of four species of bats, which inhabit the Negev desert in Israel, one species mainly restricted to hyper-arid deserts (Otonycteris hemprichii), two species from semi-desert areas (Eptesicus bottae and Plecotus christii), and one widespread species (Pipistrellus kuhlii). We also measured separately, in the same individuals, the two components of TEWL, respiratory water loss (RWL) and cutaneous evaporative water loss (CEWL), using a mask. In all the species, MR and TEWL were significantly reduced during torpor, the latter being a consequence of reductions in both RWL and CEWL. Then, we evaluated whether MR and TEWL in bats differ according to their geographic distributions, and whether those rates change with T a and the use of torpor. We did not find significant differences in MR among species, but we found that TEWL was lowest in the species restricted to desert habitats, intermediate in the semi-desert dwelling species, and highest in the widespread species, perhaps a consequence of adaptation to life in deserts. Our results were supported by a subsequent analysis of data collected from the literature on rates of TEWL for 35 bat species from desert and mesic habitats.

      PubDate: 2015-11-01T10:20:18Z
  • Differential distribution of lipids in epidermis, gastrodermis and hosted
           Symbiodinium in the sea anemone Anemonia viridis
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Johana Revel, Lionel Massi, Mohamed Mehiri, Marc Boutoute, Patrick Mayzaud, Laure Capron, Cécile Sabourault
      Cnidarian–dinoflagellate symbiosis mainly relies on nutrient recycling, thus providing both partners with a competitive advantage in nutrient-poor waters. Essential processes related to lipid metabolism can be influenced by various factors, including hyperthermal stress. This can affect the lipid content and distribution in both partners, while contributing to symbiosis disruption and bleaching. In order to gain further insight into the role and distribution of lipids in the cnidarian metabolism, we investigated the lipid composition of the sea anemone Anemonia viridis and its photosynthetic dinoflagellate endosymbionts (Symbiodinium). We compared the lipid content and fatty acid profiles of the host cellular layers, non-symbiotic epidermal and symbiont-containing gastrodermal cells, and those of Symbiodinium, in a mass spectrometry-based assessment. Lipids were more concentrated in Symbiodinium cells, and the lipid class distribution was dominated by polar lipids in all tissues. The fatty acid distribution between host cell layers and Symbiodinium cells suggested potential lipid transfers between the partners. The lipid composition and distribution was modified during short-term hyperthermal stress, mainly in Symbiodinium cells and gastrodermis. Exposure to elevated temperature rapidly caused a decrease in polar lipid C18 unsaturated fatty acids and a strong and rapid decrease in the abundance of polar lipid fatty acids relative to sterols. These lipid indicators could therefore be used as sensitive biomarkers to assess the physiology of symbiotic cnidarians, especially the effect of thermal stress at the onset of cnidarian bleaching. Overall, the findings of this study provide some insight on key lipids that may regulate maintenance of the symbiotic interaction.

      PubDate: 2015-10-28T10:11:25Z
  • Vitamin A and arachidonic acid altered the skeletal mineralization in
           Atlantic cod (Gadus morhua) larvae without any interactions on the
           transcriptional level
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Kai Kristoffer Lie, Karen Kvalheim, Josef Daniel Rasinger, Torstein Harboe, Andreas Nordgreen, Mari Moren
      The main object of this study was to evaluate the impact of different levels of vitamin A (VA) and arachidonic acid (ARA) in relation to eicosapentaenoic acid (EPA) on mineralization and gene expression in Atlantic cod larvae (Gadus morhua). First-feeding larvae were fed enriched rotifers from start-feeding until 29days post hatch (dph). Larvae in four tanks were fed one of the following diets: control (EPA/ARA ratio: 15.8, 0.9μg VA g−1), control+VA (EPA/ARA ratio: 15.8, 7.8μg VA g−1), High ARA (EPA/ARA ratio: 0.9, 1.5μg VA g−1) or High ARA+VA (EPA/ARA ratio: 0.9, 12.0μg VA g−1). Larvae fed High ARA+VA were shorter at 29dph compared to the other groups and had significantly less mineralized bones when comparing larvae of similar size, showing interaction effects between VA and ARA. Although transcriptomic analysis did not reveal any interaction effects, a higher number of genes were differentially expressed in the high ARA fed larvae compared to control+VA fed larvae. Furthermore, bglap1, bglap2 and col10a1 were all down-regulated in larvae fed High ARA-diets and to a greater extent than larvae fed VA supplemented diet, indicating an additive effect on mineralization. In conclusion, this study showed that the dietary increase in ARA and VA altered the skeletal metabolism during larval development, most likely through signaling pathways specific for each nutrient rather than an interaction. The present study also demonstrates that VA could affect the larval response to ARA, even within the accepted non-toxic/non-deficient range.

      PubDate: 2015-10-28T10:11:25Z
  • Effect of sulfide, osmotic, and thermal stresses on taurine transporter
           mRNA levels in the gills of the hydrothermal vent-specific mussel
           Bathymodiolus septemdierum
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Ikumi Nakamura-Kusakabe, Toshihiro Nagasaki, Azusa Kinjo, Mieko Sassa, Tomoko Koito, Kei Okamura, Shosei Yamagami, Toshiro Yamanaka, Shinji Tsuchida, Koji Inoue
      Hydrothermal vent environmental conditions are characterized by high sulfide concentrations, fluctuating osmolality, and irregular temperature elevations caused by vent effluents. These parameters represent potential stressors for organisms that inhabit the area around hydrothermal vents. Here, we aimed to obtain a better understanding of the adaptation mechanisms of marine species to hydrothermal vent environments. Specifically, we examined the effect of sulfide, osmolality, and thermal stress on the expression of taurine transporter (TAUT) mRNA in the gill of the deep-sea mussel Bathymodiolus septemdierum, which is a dominant species around hydrothermal vent sites. We analyzed TAUT mRNA levels by quantitative real-time polymerase chain reaction (PCR) in the gill of mussels exposed to sulfide (0.1 or 1mg/L Na2S·9H2O), hyper- (115% seawater) and hypo- (97.5%, 95.5%, and 85% seawater) osmotic conditions, and thermal stresses (12°C and 20°C) for 24 and 48h. The results showed that mussels exposed to relatively low levels of sulfide (0.1mg/L) and moderate heat stress (12°C) exhibited higher TAUT mRNA levels than the control. Although hyper- and hypo-osmotic stress did not significantly change TAUT mRNA levels, slight induction was observed in mussels exposed to low osmolality. Our results indicate that TAUT is involved in the coping mechanism of mussels to various hydrothermal vent stresses.

      PubDate: 2015-10-28T10:11:25Z
  • Abundance of specific mRNA transcripts impacts hatching success in
           European eel, Anguilla anguilla L
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Christoffer Rozenfeld, Ian A.E. Butts, Jonna Tomkiewicz, Jose-Luis Zambonino-Infante, David Mazurais
      Maternal mRNA governs early embryonic development in fish and variation in abundance of maternal transcripts may contribute to variation in embryonic survival and hatch success in European eel, Anguilla anguilla. Previous studies have shown that quantities of the maternal gene products β-tubulin, insulin-like growth factor 2 (igf2), nucleoplasmin (npm2), prohibitin 2 (phb2), phosphatidylinositol glycan biosynthesis class F protein 5 (pigf5), and carnitine O-palmitoyltransferase liver isoform-like 1 (cpt1) are associated with embryonic developmental competence in other teleosts. Here, the relations between relative mRNA abundance of these genes in eggs and/or embryos and egg quality, was studied and analyzed. We compared egg quality of the two groups: i) batches with hatching and ii) batches with no hatching. Results showed no significant differences in relative mRNA abundance between the hatch and no hatching groups for any of the selected genes at 0, 2.5, and 5HPF. However, at 30HPF the hatch group showed significantly higher abundance of cpt1a, cpt1b, β-tubulin, phb2, and pigf5 transcripts than the no hatch group. Therefore, these results indicate that up-regulation of the transcription of these genes in European eel after the mid-blastula transition, may be needed to sustain embryonic development and hatching success.

      PubDate: 2015-10-28T10:11:25Z
  • Role of PACAP on testosterone and 17β-estradiol production in the
           testis of wall lizard Podarcis sicula
    • Abstract: Publication date: Available online 27 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Luigi Rosati, Marina Prisco, Maria Maddalena Di Fiore, Alessandra Santillo, Salvatore Valiante, Piero Andreuccetti, Marisa Agnese
      Pituitary adenylate cyclase-activating peptide (PACAP) is a neuropeptide that in mammalian testis is involved in the control of testosterone and 17β-estradiol synthesis. A similar involvement was recently postulated in the testis of a non mammalian vertebrate, the wall lizard Podarcis sicula. Indeed, we reported the presence of PACAP and its receptors throughout the reproductive cycle within both germ and somatic cells. Now, we investigated the effects of PACAP on steroidogenesis in significant periods of Podarcis reproductive cycle: winter stasis, reproductive period and summer stasis. Using different in vitro treatments, in absence or presence of receptor antagonists, we demonstrated that in Podarcis sicula testis PACAP is involved in the control of testosterone and 17β-estradiol production. In particular we demonstrated that treatment with PACAP induced a testosterone increase only in stasis periods (Winter and Summer stasis); differently they induced a 17β-estradiol production in all periods analyzed (Summer stasis, Winter stasis and Reproductive period).

      PubDate: 2015-10-28T10:11:25Z
  • Metabolic activity and behavior of the invasive amphipod Dikerogammarus
           villosus and two common Central European gammarid species (Gammarus
           fossarum, Gammarus roeselii): Low metabolic rates may favor the invader
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Jochen Becker, Christian Ortmann, Markus A. Wetzel, Jochen H.E. Koop
      The Ponto-Caspian amphipod Dikerogammarus villosus is one of the most successful invaders in Central European rivers. Contrary to studies on its ecology, ecophysiological studies comparing the species' physiological traits are scarce. In this context, in particular the metabolic activity of the invasive species has rarely been considered and, moreover, the few existing studies on this species report strongly deviating results. The purpose of this study was to assess the metabolic activity and behavior of D. villosus and other common European amphipod species (Gammarus fossarum, Gammarus roeselii) in relation to temperatures covering the thermal regime of the invaded habitats. Based on direct calorimetric measurements of metabolic heat dissipation at three temperature levels (5°C, 15°C and 25°C), we found the routine metabolic rate of D. villosus to be significantly lower than that of the other studied gammarid species at the medium temperature level. The estimated resting metabolic rate indicated a similar trend. At 5°C and 25°C, both routine and resting metabolic rate did not differ between species. Compared to G. fossarum and G. roeselii, D. villosus exhibited lower locomotor activity at the low and medium temperatures (5°C and 15°C). In contrast, its locomotor activity increased at the high experimental temperature (25°C). G. fossarum and G. roeselii were apparently more active than D. villosus at all studied temperatures. We conclude that D. villosus has both physiological and behavioral adaptations that lead to a reduction in metabolic energy expenditure, which is assumed to be beneficial and might contribute to its invasive success.

      PubDate: 2015-10-28T10:11:25Z
  • Role of calcium on the initiation of sperm motility in the European eel
    • Abstract: Publication date: Available online 11 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Luz Pérez, M. Carmen Vílchez, Víctor Gallego, Marina Morini, David S. Peñaranda, Juan F. Asturiano
      Sperm from European eel males treated with hCGrec was washed in a calcium free extender, and sperm motility was activated both in the presence (seawater, SW) and in the absence of calcium (NaCl+EDTA), and treated with calcium inhibitors or modulators. The sperm motility parameters were evaluated by a computer-assisted sperm analysis (CASA) system, and changes in the [Ca2+]i fluorescence (and in [Na+]i in some cases) were evaluated by flow cytometry. After sperm motility was activated in a medium containing Ca2+ (seawater, SW) the intracellular fluorescence emitted by Ca2+ increased 4-6-fold compared to the levels in quiescent sperm. However, whilst sperm activation in a Ca-free media (NaCl+EDTA) resulted in a percentage of motility similar to seawater, the [Ca2+]i levels did not increase at all. This result strongly suggests that increasing [Ca2+]i is not a pre-requisite for the induction of sperm motility in European eel sperm. Several sperm velocities (VCL, VSL, VAP) decreased when sperm was activated in the Ca-free activator, thus supporting the theory that Ca2+ has a modulatory effect on sperm motility. The results indicate that a calcium/sodium exchanger (NCX) which is inhibited by bepridil and a calcium calmodulin kinase (inhibited by W-7), are involved in the sperm motility of the European eel. Our results indicate that the increase in [Ca2+]i concentrations during sperm activation is due to an influx from the external medium, but, unlike in most other species, it does not appear to be necessary for the activation of motility in European eel sperm.

      PubDate: 2015-10-11T23:55:26Z
  • Exogenous administration of chronic corticosterone affects hepatic
           cholesterol metabolism in broiler chickens showing long or short tonic
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Jie Liu, Yujing Duan, Yun Hu, Lili Sun, Song Wang, Wenyan Fu, Yingdong Ni, Ruqian Zhao
      Tonic immobility (TI) is an innate characteristic of animals related to fear or stress response. Animals can be classified into long TI (LTI) and short TI (STI) phenotypes based on TI test duration. In this study, effect of TI phenotype, chronic corticosterone administration (CORT), and their interaction on cholesterol metabolism in liver was evaluated in broilers. LTI broilers showed higher level of cholesterol in liver compared to STI chickens (p<0.05), and CORT significantly increased hepatic cholesterol content (p<0.01). Real-time PCR results showed that both TI and CORT potentially altered ABCA1 and CYP7A1 gene expressions (0.05<p<0.1), while there was no significant interaction of CORT and TI on both gene expressions. CORT treatment significantly increased the level of SREBP2 (p=0.00), LDLR (p<0.05), GR (p<0.05) and 11β-HSD2 (p<0.05) protein abundance in liver. However, TI phenotype only affected hepatic HMGCR protein expression, and LTI broilers showed higher level of HMGCR protein expression in liver than STI (p<0.05). These results indicate that chronic CORT administration causes hepatic cholesterol accumulation in broiler chickens mainly by enhancing cholesterol synthesis and uptake into liver. LTI chickens had higher amount of total cholesterol in liver, which might be associated with an increase of hepatic HMGCR protein expression. However, there is no interaction between TI and CORT on cholesterol metabolism in liver of broilers.

      PubDate: 2015-10-11T23:55:26Z
  • Acclimation of killifish to thermal extremes of hot spring: Transcription
           of gonadal and liver heat shock genes
    • Abstract: Publication date: Available online 11 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Arash Akbarzadeh, Erica H. Leder
      Some killifish species are known to thrive in the thermal extreme of hot springs, and it is likely that they have evolved novel mechanisms to achieve thermal tolerance. In this study, we explored the hypothesis that killifish acclimate to thermal extremes through regulation of genes involved in stress and metabolism. We examined the liver and gonadal transcription of heat shock proteins (hsp70, hsp90ɑ, hsp90b), glucokinase (gck), and high mobility group b1 (hmgb1) protein in wild killifish species from hot springs and rivers using quantitative real-time PCR. Moreover, we exposed a river killifish species Aphanius dispar to a long-term thermal regime of hot spring (37-40°C) and examined the liver transcription of the heat shock genes. Hot spring killifish with temperature 37–40°C showed a significant, strong upregulation of liver hsp90a, while gck mRNA expression was the highest in river killifish. The results of mRNA expression in gonadal (ovary and testis) tissues of male and female killifish showed that the transcripts of both isoforms of hsp90 were much more upregulated in testis of males than ovary of females. Moreover, the testicular transcript levels of hsp90a, hsp90b and hsp70 were higher in hot spring killifish than the river ones. The results of the common garden experiments showed that the transcripts of hsp70, hsp90b and hmgb1were mildly induced (>twofold) at the time when temperature reached to 37-40°C, while the transcripts of the other paralog encoding for hsp90a was strongly induced (17 fold increase). The level of hsp70 and hsp90b transcripts decreased from their initial levels after long-term exposure to elevated temperatures, while hsp90a was dramatically more upregulated when fish were maintained in thermal extreme (42-fold change higher than in ambient temperature). Moreover, liver gck transcript levels were strongly affected by temperature, so that significant downregulation of gck transcripts was observed at the time when temperature was raised to 37-40 °C (80-fold decrease) and during exposure to long term thermal extreme (56-fold decrease). It can be concluded that the regulation of heat shock genes particularly hsp90a might be a key factor of the acclimation of fish to high temperature environments like hot springs.

      PubDate: 2015-10-11T23:55:26Z
  • Editorial Board
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190

      PubDate: 2015-10-11T23:55:26Z
  • Avian energetics: The passerine/non-passerine dichotomy
    • Abstract: Publication date: Available online 9 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Brian K. McNab
      Whether passerines collectively have a higher mean mass-independent basal rate of metabolism than the mean of other birds has been controversial. The conclusion that no difference exists was based on phylogenetic analyses. Higher basal rates, however, have been repeatedly seen in passerines and demonstrated by ANCOVA analyses. Several studies indicated that the mean mass-independent basal rate of passerines is > 30% higher than the collective mean of other birds. Yet, at least three non-passerine orders of 25 have mean mass-independent basal rates equal to that of passerines. They are Anseriformes, Charadriiformes, and Procellariiformes, all characterized by an active lifestyle, including migratory and pelagic habits. In contrast, sedentary ducks endemic to islands have low basal rates. The high basal rates in temperate passerines correlate with migratory habits and life in cool to cold environments, the absence of these factors being partly responsible for the lower basal rates in most tropical passerines. The principal difference in energetics among non-passerines, between passerines and most non-passerines, and among passerines reflects the frequency of habits associated with high or low mass-independent energy expenditures, the habits correlating with body composition. The mean mass-independent basal rate in tropical passerines is slightly lower than in temperate passerines which implies that the collective mean in passerines would be somewhat lower if tropical passerines were included in proportion to their diversity. However, their inclusion will not eliminate the difference presently seen between passerines and other birds because the difference between tropical and temperate passerines is less than that between passerines and other birds.

      PubDate: 2015-10-11T23:55:26Z
  • Methane production by two non-ruminant foregut-fermenting herbivores: The
           collared peccary (Pecari tajacu) and the pygmy hippopotamus (Hexaprotodon
    • Abstract: Publication date: Available online 9 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Catharina Vendl, Samuel Frei, Marie Theres Dittmann, Samuel Furrer, Sylvia Ortmann, Arne Lawrenz, Bastian Lange, Adam Munn, Michael Kreuzer, Marcus Clauss
      Methane (CH4) production varies between herbivore species, but reasons for this variation remain to be elucidated. Here, we report open-circuit chamber respiration measurements of CH4 production in four specimens each of two non-ruminant mammalian herbivores with a complex forestomach but largely differing in body size, the collared peccary (Pecari tajacu, mean body mass 17kg) and the pygmy hippopotamus (Hexaprotodon liberiensis, 229kg) fed lucerne-based diets. In addition, food intake, digestibility and mean retention times were measured in the same experiments. CH4 production averaged 8 and 72L/d, 18 and 19L/kg dry matter intake, and 4.0 and 4.2% of gross energy intake for the two species, respectively. When compared with previously reported data on CH4 production in other non-ruminant and ruminant foregut-fermenting as well as hindgut-fermenting species, it is evident that neither the question whether a species is a foregut fermenter or not, or whether it ruminates or not, is of the relevance previously suggested to explain variation in CH4 production between species. Rather, differences in CH4 production between species on similar diets appear related to species-specific differences in food intake and digesta retention kinetics.

      PubDate: 2015-10-11T23:55:26Z
  • Physiological responses to digestion in low salinity in the crabs Carcinus
           maenas and Cancer irroratus
    • Abstract: Publication date: Available online 10 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chantelle M. Penney, Richard L. Patton, Nia M. Whiteley, William R. Driedzic, Iain J. McGaw
      Osmoregulation and digestion are energetically demanding, and crabs that move into low salinity environments to feed must be able to balance the demands of both processes. Achieving this balance may pose greater challenges for weak than for efficient osmoregulators. This study examined the rate of oxygen consumption (MO2) of Carcinus maenas (efficient osmoregulator) and Cancer irroratus (weak osmoregulator) as a function of feeding and hyposaline stress. The MO2 increased 2-fold in both species following feeding. The MO2 increased and remained elevated in fasted crabs during acute hyposaline exposure. When hyposaline stress occurred after feeding, C. maenas responded with an immediate summation of the MO2 associated with feeding and hyposaline stress, whereas C. irroratus reacted with a partial summation of responses in a salinity of 24‰, but were unable to sum responses in 16‰. C. irroratus exhibited longer gut transit times. This may be due to an inability to regulate osmotic water onload as efficiently as C. maenas. Mechanical digestion in crabs can account for a significant portion of SDA, and a short term interruption led to the delay in summation of metabolic demands. Although protein synthesis is reported to account for the majority of SDA, this did not appear to be the case here. Protein synthesis rates were higher in C. irroratus but neither feeding or salinity affected protein synthesis rates of either species which suggests that protein synthesis can continue in low salinity as long as substrates are available.

      PubDate: 2015-10-11T23:55:26Z
  • Bacteria-killing ability of fresh blood plasma compared to frozen blood
    • Abstract: Publication date: Available online 9 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anne C. Jacobs, Jeanne M. Fair
      In recent years, the bacteria-killing assay (BKA) has become a popular technique among ecoimmunologists. New variations of that assay allow researchers to use smaller volumes of blood, an important consideration for those working on small-bodied animals. However, this version of the assay requires access to a lab with a Nanodrop spectrophotometer, something that may not be available in the field. One possible solution is to freeze plasma for transport; however, this assumes that frozen plasma samples will give comparable results to fresh ones. We tested this assumption using plasma samples from three species of birds: chickens (Gallus gallus), ash-throated flycatchers (Myiarchus cinerascens), and western bluebirds (Sialia mexicana). Chicken plasma samples lost most or all of their bacterial killing ability after freezing. This did not happen in flycatchers and bluebirds; however, frozen plasma did not produce results comparable to those obtained using fresh plasma. We caution researchers using the BKA to use fresh samples whenever possible, and to validate the use of frozen samples on a species-by-species basis.

      PubDate: 2015-10-11T23:55:26Z
  • Plasticity of protective mechanisms only partially explains interactive
           effects of temperature and UVR on upper thermal limits
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): Pippa Kern, Rebecca L. Cramp, Frank Seebacher, Ensiyeh Ghanizadeh Kazerouni, Craig E. Franklin
      Temperature and ultraviolet radiation (UVR) are key environmental drivers that are linked in their effects on cellular damage. Exposure to both high temperatures and UVR can cause cellular damage that result in the up-regulation of common protective mechanisms, such as the induction of heat shock proteins (Hsps) and antioxidants. As such, the interactive effects of these stressors at the cellular level may determine physiological limits, such as thermal tolerance. Furthermore, antioxidant activity is often thermally sensitive, which may lead to temperature dependent effects of UVR exposure. Here we examined the interactive effects of temperature and UVR on upper thermal limits, Hsp70 abundance, oxidative damage and antioxidant (catalase) activity. We exposed Limnodynastes peronii tadpoles to one of three temperature treatments (constant 18°C, constant 28°C and daily fluctuations between 18 and 28°C) in the presence or absence of UVR. Tadpoles were tested for upper thermal limits (CTmax), induction of Hsp70, oxidative damage and catalase activity. Our results show that CTmax was influenced by an interactive effect between temperature and UVR treatment. For tadpoles kept in cold temperatures, exposure to UVR led to cross-tolerance to high temperatures, increasing CTmax. Plasticity in this trait was not fully explained by changes in the lower level mechanistic traits examined. These results highlight the difficulty in predicting the mechanistic basis for the interactive effects of multiple stressors on whole animal traits. Multifactorial studies may therefore be required to understand how complex mechanistic processes shape physiological tolerances, and determine responses to environmental variation.

      PubDate: 2015-10-08T08:55:32Z
  • Coronary blood flow in the anesthetized American alligator (Alligator
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Bjarke Jensen, Magnus Elfwing, Ruth M. Elsey, Tobias Wang, Dane A. Crossley
      Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American alligators (Alligator mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressure.

      PubDate: 2015-10-08T08:55:32Z
  • Plasma levels of follicle-stimulating and luteinizing hormones during the
           reproductive cycle of wild and cultured Senegalese sole (Solea
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): François Chauvigné, Elvira Fatsini, Neil Duncan, Judith Ollé, Silvia Zanuy, Ana Gómez, Joan Cerdà
      The intensive culture of the Senegalese sole (Solea senegalensis) is hampered by the low or null fertilization rates exhibited by the first generation (F1) of reared males. To investigate the regulation of the reproductive processes in this species by the pituitary gonadotropins follicle-stimulating and luteinizing hormones (Fsh and Lh, respectively), we developed a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) for Lh measurements. Quantification of the Fsh and Lh plasma levels in cultured sole using the Lh ELISA developed here, and a previously developed ELISA for Fsh, indicated that in both males and females circulating Fsh steadily increased during autumn and winter and prior to the major spawning in spring, whereas an Lh surge occurred specifically during spawning. The increase in Fsh was associated with a rise of plasma levels of the steroid hormones testosterone (T), 11-ketotestosterone (11-KT) and estradiol-17β (E2), but that of Lh was concomitant with a strong decline of the levels of E2 in females and of 11-KT in males, possibly reflecting a rapid steroidogenic shift promoting the final maturation of gametes. Comparison of the plasma levels of gonadotropins and steroids between wild and F1 fish during autumn and spring revealed that F1 males showed significantly lower plasma Lh titres compared to wild males, whereas the levels of T and 11-KT were similar or more elevated in the F1 fish. These data suggest that an impaired Lh secretion during spawning, and perhaps altered Lh-mediated mechanisms in the testis, may be underlying causes for the low reproductive performance of Senegalese sole F1 males.

      PubDate: 2015-10-08T08:55:32Z
  • Energy metabolism of hyperthyroid-induced gilthead sea bream Sparus aurata
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Luis Vargas-Chacoff, Ignacio Ruiz-Jarabo, Francisco J. Arjona, Raúl Laiz-Carrión, Gert Flik, Peter H.M. Klaren, Juan M. Mancera
      Thyroid hormones, in particular 3,5,3′-triiodothyronine or T3, are involved in multiple physiological processes in mammals such as protein, fat and carbohydrate metabolism. However, the metabolic actions of T3 in fish are still not fully elucidated. We therefore tested the effects of T3 on Sparus aurata energy metabolism and osmoregulatory system, a hyperthyroid-induced model that was chosen. Fish were implanted with coconut oil depots (containing 0, 2.5, 5.0 and 10.0μgT3/g body weight) and sampled at day 3 and 6 post-implantation. Plasma levels of free T3 as well as glucose, lactate and triglyceride values increased with increasing doses of T3 at days 3 and 6 post-implantation. Changes in plasma and organ metabolite levels (glucose, glycogen, triglycerides, lactate and total α amino acid) and enzyme activities related to carbohydrate, lactate, amino acid and lipid pathways were detected in organs involved in metabolism (liver) and osmoregulation (gills and kidney). Our data implicate that the liver uses amino acids as an energy source in response to the T3 treatment, increasing protein catabolism and gluconeogenic pathways. The gills, the most important extruder of ammonia, are fuelled not only by amino acids, but also by lactate. The kidney differs significantly in its substrate preference from the gills, as it obtained metabolic energy from lactate but also from lipid oxidation processes. We conclude that in S. aurata lipid catabolism and protein turnover are increased as a consequence of experimentally induced hyperthyroidism, with secondary osmoregulatory effects.

      PubDate: 2015-10-08T08:55:32Z
  • Heat and oxidative stress alter the expression of orexin and its related
           receptors in avian liver cells
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Elizabeth Greene, Stephanie Khaldi, Peter Ishola, Walter Bottje, Takeshi Ohkubo, Nicholas Anthony, Sami Dridi
      Orexins (A and B) or hypocretins (1 and 2) are hypothalamic orexigenic neuropeptides that are involved in the regulation of several physiological processes in mammals. Recently, orexin has been shown to activate the hypothalamic-pituitary-adrenal (HPA) stress axis and emerging evidences identify it as a stress modulator in mammals. However, the regulation of orexin system by stress itself remains unclear. Here, we investigate the effects of heat, 4-Hydroxynonenal (4-HNE) and hydrogen peroxide (H2O2) stress on the hepatic expression of orexin (ORX) and its related receptors (ORXR1/2) in avian species. Using in vivo and in vitro models, we found that heat stress significantly down-regulated ORX and ORXR1/2 mRNA and protein abundances in quail liver and LMH cells. H2O2, however, decreased ORX protein and increased ORX mRNA levels in a dose dependent manner (P <0.05). The absence of correlation between orexin mRNA and protein levels suggests that H2O2 treatment modulates post-transcriptional mechanisms. 4-HNE had a biphasic effect on orexin system expression, with a significant up-regulation at low doses (10 and 20μM) and a significant down-regulation at a high dose (30μM). Taken together, our data indicated that hepatic orexin system could be a molecular signature in the heat and oxidative stress response.

      PubDate: 2015-10-08T08:55:32Z
  • Dietary glutamine supplementation effects on amino acid metabolism,
           intestinal nutrient absorption capacity and antioxidant response of
           gilthead sea bream (Sparus aurata) juveniles
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): F. Coutinho, C. Castro, E. Rufino-Palomares, B. Ordóñez-Grande, M.A. Gallardo, A. Oliva-Teles, H. Peres
      A study was undertaken to evaluate dietary glutamine supplementation effects on gilthead sea bream performance, intestinal nutrient absorption capacity, hepatic and intestinal glutamine metabolism and oxidative status. For that purpose gilthead sea bream juveniles (mean weight 13.0g) were fed four isolipidic (18% lipid) and isonitrogenous (43% protein) diets supplemented with 0, 0.5, 1 and 2% glutamine for 6weeks. Fish performance, body composition and intestinal nutrient absorption capacity were not affected by dietary glutamine levels. Hepatic and intestinal glutaminase (GlNase), glutamine synthetase (GSase), alanine aminotransferase, aspartate aminotransferase and glutamate dehydrogenase activities were also unaffected by dietary glutamine supplementation. In the intestine GlNase activity was higher and GSase/GlNase ratio was two-fold lower than in the liver, suggesting a higher use of glutamine for energy production by the intestine than by the liver. The liver showed higher catalase and glucose-6-phosphate dehydrogenase activities, while the intestine presented higher glutathione peroxidase and glutathione reductase activities and oxidised glutathione content, which seems to reveal a higher glutathione dependency of the intestinal antioxidant response. Total and reduced glutathione contents in liver and intestine and superoxide dismutase activity in the intestine were enhanced by dietary glutamine, though lipid peroxidation values were not affected. Overall, differences between liver and intestine glutamine metabolism and antioxidant response were identified and the potential of dietary glutamine supplementation to gilthead sea bream's antioxidant response was elucidated.

      PubDate: 2015-10-08T08:55:32Z
  • Brain size and thermoregulation during the evolution of the genus Homo
    • Abstract: Publication date: Available online 3 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel E. Naya, Hugo Naya, Enrique P. Lessa
      Several hypotheses have been proposed to explain the evolution of an energetically costly brain in the genus Homo. Some of these hypotheses are based on the correlation between climatic factors and brain size recorded for this genus during the last millions of years. In this study, we propose a complementary climatic hypothesis that is based on the mechanistic connection between ambient temperature, thermoregulatory costs, and size of internal organs that exist in endothermic species. Specifically, we hypothesized that global cooling during the last 3.2 my may have imposed an increased energy expenditure for thermoregulation, which in the case of hominids could represent an evolutionary driver for the evolution of an expanded, heat generating brain, or, at the very least, it could imply the relaxation of a negative selection pressure acting upon the size of this energetically expensive organ. To test this idea, here we (1) assess variation in the energetic costs of thermoregulation and brain maintenance for the last 3.2 my, and (2) evaluate the relationship between Earth temperature and brain maintenance cost for the same period, taking into account the effects of body mass and fossil age. We found that: (1) the increase in thermoregulatory costs is greater than those associated with brain enlargement, and, at the same time, the energetic cost associated with brain enlargement represent an important fraction (between 47.5% and 82.5%) of the increase in energy needed for thermoregulation; (2) fossil age is a better predictor of brain maintenance cost than Earth temperature, suggesting that (at least) another factor correlated with time was more relevant than ambient temperature in brain size evolution; and (3) there is a significant negative correlation between the energetic cost of brain and Earth temperature, even after accounting for the effect of body mass and fossil age. Thus, our results expand the current energetic framework for the study of brain size evolution in our lineage by suggesting that the fall in Earth temperature that occurred during the last millions of years may have facilitated brain enlargement.

      PubDate: 2015-10-08T08:55:32Z
  • Field studies on the annual activity and the metabolic responses of a land
           snail population living in high altitude
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Alexandra Staikou, George Tachtatzis, Konstantinos Feidantsis, Basile Michaelidis
      In the context of the metabolic cold adaptation hypothesis (MCA), we investigated a) the life and activity cycle characteristics and b) the metabolic responses of the endemic land snail species Cattania trizona olympica living at 1100m altitude in Olympus mountain (Greece). Field observations on the annual activity cycle of C. trizona olympica revealed that snails' activity was restricted mainly between the end of May and September, when the higher temperatures were recorded, while first matings were recorded in July and the last ones in mid September indicating a restricted favorable time period for reproduction. The activities of enzymes of intermediate metabolism showed a periodic seasonal pattern of change which seems to be closely related to the pattern of annual changes of air temperature and most of them exhibited higher activities during the coldest and warmest periods of the year. Moreover the data indicate a distinct differentiation of fuel oxidation during arousal and reproductive periods with lipid oxidation, apart from carbohydrates, contributing significantly to ATP turnover during reproductive activity. The higher enzymatic activities, determined in the tissues of C. trizona olympica than the corresponding ones determined in the tissues of the land snail species living at low altitudes, might indicate higher sensitivity of the intermediate metabolism and ATP turnover in C. trizona olympica to changes in environmental factors. Although the latter seems to be in line with the MCA hypothesis, it needs further investigation on metabolic rates to support it.

      PubDate: 2015-10-03T08:45:24Z
  • Effects of nicotine on the digestive performance of nectar-feeding birds
           reflect their relative tolerance to this alkaloid
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): S. Lerch-Henning, S.W. Nicolson
      The paradox of secondary metabolites, toxic defence compounds produced by plants, in nectar and fruits is well known. Deterrence of feeding by nectarivorous and frugivorous birds is better understood than the effect of these chemicals on the digestive performance of birds. Digestive parameters such as transit time and sugar assimilation are important in assessing nutrient utilization and deterrence may be related to post-ingestive effects involving these parameters. Nectar and many fruits contain mainly sugars and water, and avian consumers compensate for low sugar content in their diet by increasing food intake: this may also increase their intake of secondary metabolites. We investigated how the alkaloid nicotine, naturally present in nectar of Nicotiana species, influences compensatory feeding and digestive performance of nectar-feeding birds. High nicotine concentration negatively affected compensatory feeding and apparent assimilation efficiency of white-bellied sunbirds Cinnyris talatala and Cape white-eyes Zosterops virens; but nicotine slowed gut transit time only in the latter species. In contrast, food intake and digestive performance of dark-capped bulbuls Pycnonotus tricolor was unaffected by nicotine up to a concentration of 50μM. Bulbuls are primarily frugivorous; hence, they are more exposed to secondary metabolites than sunbirds and possibly white-eyes. Because their diet is richer in toxins, frugivorous birds may have evolved more efficient detoxification strategies than those of specialist nectar-feeding birds.

      PubDate: 2015-09-30T02:06:33Z
  • Experimentally increased temperature and hypoxia affect stability of
           social hierarchy and metabolism of the Amazonian cichlid Apistogramma
    • Abstract: Publication date: Available online 24 September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daiani Kochhann, Derek Felipe Campos, Adalberto Luis Val
      The primary goal of this study was to understand how changes in temperature and oxygen could influence social behaviour and aerobic metabolism of the Amazonian dwarf cichlid Apistogramma agassizii. Social hierarchies were established over a period of 96h by observing the social interactions, feeding behaviour and shelter use in groups of four males. In the experimental environment, temperature was increased to 29°C in the high-temperature treatment, and oxygen lowered to 1.0mg.L−1 O2 in the hypoxia treatment. After the stabilization period, fish were maintained at this control condition for 96h to allow hierarchies to stabilise. The control condition was maintained at 26°C and 6.6mg.L−1 O2. After the experimental exposure, metabolism was measured as routine metabolic rate (RMR) and electron transport system (ETS) activity. There was a reduction in hierarchy stability at high temperatures. Aggression levels changed after environmental changes. Dominant and subdominant fish at high temperatures increased their biting, compared to dominant fish from controls. In contrast, dominant fish exposed to hypoxia decreased their aggressive acts compared to all other fish. Shelter use decreased in dominant fish under control and hypoxic conditions. Dominant fish from undisturbed environments eat more than their subordinates. There was a decrease of RMR in fish exposed to the hypoxic environment when compared to fish from control or high-temperature environment independently of social position. Dominant fish had higher RMR than their subordinates in the control condition. ETS activity increased in fish exposed to high temperatures; however, there was no effect on social rank. Our study reinforces the importance of environmental changes for the maintenance of hierarchies and their characteristics and highlight that most of the changes occur in the dominant position.

      PubDate: 2015-09-26T02:03:28Z
  • Does metabolic rate and evaporative water loss reflect differences in
           migratory strategy in sexually dimorphic hoverflies'
    • Abstract: Publication date: Available online 15 September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sean Tomlinson, Myles H.M. Menz
      A typical explanation for ecologically stable strategies that apply to, or are exploited by only a proportion of a population is bet hedging, where lifetime fitness is maximised by individuals reducing their annual variance in reproductive success. Such variable strategies offset reduced reproductive rate against increased reproductive success. One such is partial migration, where only a proportion of a population moves seasonally to avoid inclement climatic conditions, while some individuals may endure the challenges of overwintering. The idea of bet hedging, however, may overlook unseen costs to maintaining a breadth of options in physiological resilience, implied by encountering a broad range of environmental conditions. We investigated the physiological correlates of partial migration by measuring standard metabolic rates, rates of evaporative water loss, and estimating upper and lower thermal tolerance in males and females of two hoverfly species, Episyrphus balteatus and Eristalis tenax. In central Europe, females of these species may either migrate or overwinter, whereas males may migrate south to the Mediterranean, but have not been found overwintering. There was sexual dimorphism in both species, where female Ep. balteatus were lighter than males, but female Er. tenax were heavier than males. While allometrically-corrected metabolic rate in both species increased with temperature, the most parsimonious models included no sex-specific differences in metabolic rate for either species. Evaporative water loss of both species also increased with temperature, but was higher for females of both species than males, across the measured temperature range. Assuming that resting metabolism is congruent with the activity requirements of migration, highly consistent thermal tolerance and metabolic rate suggests that any given fly could migrate, although water loss patterns suggest that females may be less-well adapted to Mediterranean climates. We infer that partial migration probably results from the ecological imperatives of their reproductive strategies, and studies on the physiology of actively migrating and overwintering individuals may be insightful.

      PubDate: 2015-09-18T01:41:44Z
  • Intraspecific variation in the energetics of the Cabrera vole
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): Elena Castellanos-Frías, Rosa García-Perea, Julio Gisbert, Francisco Bozinovic, Emilio Virgós
      Basal metabolic rate (BMR) is an intensively topic studied in ecophysiology for the purpose of understanding energy budgets of the species, variations of energy expenditure during their diary activities and physiological acclimatization to the environment. Establishing how the metabolism is assembled to the environment can provide valuable data to improve conservation strategies of endangered species. In this sense, metabolic differences associated to habitats have been widely reported in the interspecific level, however little is known about the intraspecific view of BMR under an environmental gradient. In this study, we researched the effect of the habitat on metabolic rate of an Iberian endemic species: Iberomys cabrerae. Animals were captured in different subpopulations of its altitudinal range and their MR was studied over a thermal gradient. MR was analyzed through a Linear Mixed Model (LMM) in which, in addition to thermal effects, the bioclimatic zone and sex also influenced the metabolism of the species. The beginning of thermoneutrality zone was set on 26.5°C and RMR was 2.3ml O2 g−1 h−1, intermediate between both bioclimatic zones. Supramediterranean subpopulations started the Tlc earlier (24.9°C) and had higher RMR than the mesomediterranean ones (26.9°C). The thermal environment together with primary productivity conditions could explain this difference in the metabolic behaviour of the Cabrera voles.

      PubDate: 2015-09-14T01:21:24Z
  • Fasting for 21days leads to changes in adipose tissue and liver physiology
           in juvenile checkered garter snakes (Thamnophis marcianus)
    • Abstract: Publication date: Available online 7 September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mary Davis, Renee Jessee, Matthew Close, Xiangping Fu, Robert Settlage, Guoqing Wang, Mark A. Cline, Elizabeth R. Gilbert
      Snakes often undergo periods of prolonged fasting and, under certain conditions, can survive multiple years without food. Despite this unique phenomenon, there are relatively few reports of the physiological adaptations to fasting in snakes. At post-prandial day 1 (fed) or 21 (fasting), brain, liver, and adipose tissues were collected from juvenile checkered garter snakes (Thamnophis marcianus). There was greater glycerol-3-phosphate dehydrogenase (G3PDH)-specific activity in the liver of fasted than fed snakes (P =0.01). The mRNA abundance of various fat metabolism–associated factors was measured in brain, liver, and adipose tissue. Lipoprotein lipase (LPL) mRNA was greater in fasted than fed snakes in the brain (P =0.04). Adipose triglyceride lipase (ATGL; P =0.006) mRNA was greater in the liver of fasted than fed snakes. In adipose tissue, expression of peroxisome proliferator-activated receptor (PPAR)γ (P =0.01), and fatty acid binding protein 4 (P =0.03) was greater in fed than fasted snakes. Analysis of adipocyte morphology revealed that cross-sectional area (P =0.095) and diameter (P =0.27) were not significantly different between fed and fasted snakes. Results suggest that mean adipocyte area can be preserved during fasting by dampening lipid biosynthesis while not changing rates of lipid hydrolysis. In the liver, however, extensive lipid remodeling may provide energy and lipoproteins to maintain lipid structural integrity during energy restriction. Because the duration of fasting was not sufficient to change adipocyte size, results suggest that the liver is important as a short-term provider of energy in the snake.

      PubDate: 2015-09-10T08:27:09Z
  • Editorial Board
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189

      PubDate: 2015-09-10T08:27:09Z
  • Analysis of steroidogenic pathway key transcripts in interrenal cells
           isolated by laser microdissection (LMD) in stressed rainbow trout
    • Abstract: Publication date: Available online 7 September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Camino Fierro-Castro, María Carmen Santa-Cruz, Marta Hernández-Sánchez, Mariana Teles, Lluís Tort
      An assessment of the key transcripts expression of the steroidogenesis-related genes in rainbow trout subjected to either acute or chronic stress was performed in both interrenal cells and whole head kidney tissue. The analysis of interrenal cells was possible thanks to the use, for the first time in this specific type of cells, of the technique of laser microdissection (LMD) which allows to isolate specific cells and process them independently of other surrounding cells in the tissue. The results indicated that both acute and chronic stressors induced a significant up-regulation of the steroidogenesis-related genes with a higher but expected degree in the isolated cells. In addition, under acute stress a delay between cortisol levels and transcript expression was found. Under chronic stress a clear relation between plasma cortisol levels, mRNA transcription and interrenal tissue area was observed, since all parameters were concomitantly increased at day 5 after stress. Moreover results indicated that the LMD technique allowed ascertaining with more precision and accuracy whether and when the steroidogenesis-related genes were significantly expressed, disregarding the noise produced by other cells present in the head kidney. Results also showed a typical physiological response in plasma parameters and a positive relationship between plasma cortisol data and transcript abundance in isolated cells. The present results may help to better understand the mechanisms behind the interrenal response to stress challenges in fish.

      PubDate: 2015-09-10T08:27:09Z
  • Measuring subcutaneous temperature and differential rates of rewarming
           from hibernation and daily torpor in two species of bats
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): Shannon E. Currie, Gerhard Körtner, Fritz Geiser
      Prolonged and remote measurement of body temperature (Tb) in undisturbed small hibernators was not possible in the past because of technological limitations. Although passive integrated transponders (PITs) have been used previously to measure subcutaneous temperature (Tsub) during daily torpor in a small marsupial, no study has attempted to use these devices at Tbs below 10°C. Therefore, we investigated whether subcutaneous interscapular PITs can be used as a viable tool for measuring Tb in a small hibernating bat (Nyctophilus gouldi; Ng) and compared it with measurements of Tb during daily torpor in a heterothermic bat (Syconycteris australis; Sa). The precision of transponders was investigated as a function of ambient temperature (Ta) and remote Tsub readings enabled us to quantify Tsub–Tb differentials during steady-state torpor and arousal. Transponders functioned well outside the manufacturer's recommended range, down to ~5°C. At rest, Tsub and rectal Tb (Trec) were strongly correlated for both bat species (Ng r2 =0.88; Sa r2 =0.95) and this was also true for N. gouldi in steady-state torpor (r2 =0.93). During induced rewarming Tsub increased faster than Trec in both species. Our results demonstrate that transponders can be used to provide accurate remote measurement of Tb in two species of bats during different physiological states, both during steady-state conditions and throughout dynamic phases such as rewarming from torpor. We show that, at least during rewarming, regional heterothermy common to larger hibernators and other hibernating bats is also present in bats capable of daily torpor.

      PubDate: 2015-09-05T07:58:45Z
  • Differential coral bleaching—Contrasting the activity and response
           of enzymatic antioxidants in symbiotic partners under thermal stress
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): Thomas Krueger, Thomas D. Hawkins, Susanne Becker, Stefanie Pontasch, Sophie Dove, Ove Hoegh-Guldberg, William Leggat, Paul L. Fisher, Simon K. Davy
      Mass coral bleaching due to thermal stress represents a major threat to the integrity and functioning of coral reefs. Thermal thresholds vary, however, between corals, partly as a result of the specific type of endosymbiotic dinoflagellate (Symbiodinium sp.) they harbour. The production of reactive oxygen species (ROS) in corals under thermal and light stress has been recognised as one mechanism that can lead to cellular damage and the loss of their symbiont population (Oxidative Theory of Coral Bleaching). Here, we compared the response of symbiont and host enzymatic antioxidants in the coral species Acropora millepora and Montipora digitata at 28°C and 33°C. A. millepora at 33°C showed a decrease in photochemical efficiency of photosystem II (PSII) and increase in maximum midday excitation pressure on PSII, with subsequent bleaching (declining photosynthetic pigment and symbiont density). M. digitata exhibited no bleaching response and photochemical changes in its symbionts were minor. The symbiont antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and catalase peroxidase showed no significant upregulation to elevated temperatures in either coral, while only catalase was significantly elevated in both coral hosts at 33°C. Increased host catalase activity in the susceptible coral after 5days at 33°C was independent of antioxidant responses in the symbiont and preceded significant declines in PSII photochemical efficiencies. This finding suggests a potential decoupling of host redox mechanisms from symbiont photophysiology and raises questions about the importance of symbiont-derived ROS in initiating coral bleaching.

      PubDate: 2015-09-05T07:58:45Z
  • Oxidative stress and antioxidant status in a lizard Phrynocephalus
           vlangalii at different altitudes or acclimated to hypoxia
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): Yang Zhang, Shiwei Liang, Jianzheng He, Yucheng Bai, Yonggang Niu, Xiaolong Tang, Dongqin Li, Qiang Chen
      Oxidative stress is a major challenge for the survival of animals living on plateaus; however, lifelong exposure to high altitudes could generate certain adaptabilities which make them more tolerant to these environments. The aim of the present study was to compare the oxidative stress and antioxidant status between low altitude (LA, 2900m) and high altitude (HA, 4200m) populations of Phrynocephalus vlangalii. The results showed that malondialdehyde levels in the HA populations decreased significantly in the brain, but markedly increased in the muscle and had no significant difference in the liver compared to LA populations. The activity of catalase in the brain was much higher in HA than LA. Except for total antioxidant capacity and glutathione reductase, other antioxidants were similar between the two populations in livers. By contrast, the levels of most antioxidants in muscle decreased markedly with elevation. We also explored the effects of hypoxia on oxidative damage and antioxidant defenses in P. vlangalii. The lizards were acclimated in a simulated hypoxic chamber (15% O2 and 8% O2) for 6weeks. The results showed that in the 8% O2 group, the levels of malondialdehyde, catalase, glutathione and total antioxidant capacity in the brain, and malondialdehyde, catalase and superoxide dismutase in the liver were significantly higher than the 15% O2 group. These findings indicate that in this species the oxidative stress and antioxidant capacity are subject to altitude and hypoxia and this lizard may have acquired some ability to deal with the oxidative stress.

      PubDate: 2015-09-01T07:36:27Z
  • Dynamics of blood viscosity regulation during hypoxic challenges in the
           chicken embryo (Gallus gallus domesticus)
    • Abstract: Publication date: December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 190
      Author(s): Zachary F. Kohl, Dane A. Crossley, Hiroshi Tazawa, Warren W. Burggren
      Hypoxia in chicken embryos increases hematocrit (Hct), blood O2 content, and blood viscosity. The latter may limit O2 transport capacity (OTC) via increased peripheral resistance. Hct increase may result from increased nucleated red blood cell concentration ([RBC]) and mean corpuscular volume (MCV) or reduced plasma volume. We hypothesized changes in Hct, hemoglobin concentration ([Hb]), [RBC] and MCV and their effects on viscosity would reduce OTC. Five experimental treatments that increase Hct were conducted on day 15 embryos: 60min water submergence with 60min recovery in air; exposure to 15% O2 with or without 5% CO2 for 24 h with 6 h recovery; or exposure to 10% O2 with or without 5% CO2 for 120 min with 120 min recovery. Control Hct, [Hb], [RBC], MCV, and viscosity were approximately 26%, 9g%, 2.0 106 μL−1, 130μm3, and 1.6mPas, respectively. All manipulations increased Hct and blood viscosity without changing blood osmolality (276mmolkg−1). Increased viscosity was attributed to increased [RBC] and MCV in submerged embryos, but solely MCV in embryos experiencing 10% O2 regardless of CO2. Blood viscosity in embryos exposed to 15% O2 increased via increased MCV alone, and viscosity was constant during recovery despite increased [RBC]. Consequently, blood viscosity was governed by MCV and [RBC] during submergence, while MCV was the strongest determinant of blood viscosity in extrinsic hypoxia with or without hypercapnia. Increased Hct and blood O2 content did not compensate for the effect of increased viscosity on OTC during these challenges.

      PubDate: 2015-09-01T07:36:27Z
  • Surviving in a semi-marine habitat: Dietary salt exposure and salt
           secretion of a New Zealand intertidal skink
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Jordi Janssen, David R. Towns, Mark Duxbury, Ignas M.A. Heitkönig
      Species that inhabit marine and intertidal ecosystems face osmoregulatory challenges, risking dehydration and increased ion concentrations in the body. Lizards need to either tolerate or regulate these increased ion concentrations. In this study, we aim to understand how Suter's skink (Oligosoma suteri), an intertidal skink restricted to shoreline habitats, is able to cope with the physiological stress of living in an extreme salt environment. We determined the diet, prey species' salt content, and nasal and cloacal salt excretion on Rangitoto and Motutapu Islands in northern New Zealand, where the skinks have contrasting access to terrestrial invertebrates. Analysis of stable isotopes suggests inter- and intra-population variability in Suter's skink diets. Intertidal invertebrates under washed up seaweed appear to compose a major part of the diet of the Rangitoto population, while the Motutapu population showed evidence for a mixed diet of terrestrial and intertidal invertebrates. Sodium content of prey species decreased with an increasing distance from the seawater. Field secretion of cations through nasal glands consisted primarily of Na+, which is consistent with other marine and intertidal species. Sodium was also the primary cation in urine. In contrast, fecal cations consisted primarily of K+. This first study into the salt secretion of an intertidal skink species provides evidence of Suter's skink's plasticity in secreting excess ions through nasal salt glands. This likely enables it to deal with the challenges of living in a semi-marine habitat.

      PubDate: 2015-08-07T04:11:43Z
  • Physiological responses of the ghost shrimp Neotrypaea uncinata (Milne
           Edwards 1837) (Decapoda: Thalassinidea) to oxygen availability and
           recovery after severe environmental hypoxia
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Félix P. Leiva, Mauricio A. Urbina, Juan Pablo Cumillaf, Paulina Gebauer, Kurt Paschke
      Hypoxia is a common and widespread phenomenon in aquatic ecosystems, imposing a significant challenge for the animals that inhabit such waters. In different habitats, however, the characteristics of these hypoxic events may differ, therefore imposing different challenges. We investigated the tolerance of adult ghost shrimp Neotrypaea uncinata (an intertidal mudflat dweller) to different partial pressures of oxygen (pO2), severe hypoxia (2kPa) and recovery from hypoxia after different exposure times, mimicking the natural tidal cycle (6h and 12h). We calculated critical oxygen tension and categorize the adult ghost shrimps as oxyregulators (R value=75.27%). All physiological measurements (metabolic rate, oxyhemocyanin, hemolymph protein and lactate concentrations) were affected by exposure to low partial pressures of oxygen, but most of them recovered (with exception of metabolic rate) control values (21kPa) after 6h under normoxic conditions. Low metabolic rate, high release of hemolymphatic proteins and anaerobic metabolism are suggested as response mechanisms to overcome hypoxic events during low tide.

      PubDate: 2015-08-07T04:11:43Z
  • Plasticity of thermal tolerance and metabolism but not water loss in an
           invasive reed frog
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Sarah J. Davies, Melodie A. McGeoch, Susana Clusella-Trullas
      Phenotypic plasticity may buffer the selection pressures on organisms that inhabit novel or rapidly-changing environments. We investigated plasticity of thermal tolerance, energetic and water loss traits and their interaction with behaviour in a small-bodied, arboreal anuran (Hyperolius marmoratus Rapp, Hyperoliidae) undergoing rapid range expansion into the winter rainfall region of South Africa. After short-term exposure to three temperatures (acclimation treatments) commonly encountered in their historical and novel ranges, frogs exhibited a broad thermal tolerance range (mean±s.d.: 42.1±2.9°C) and higher plasticity in CTmax than in CTmin. Resting metabolic rate was lowest in cold-acclimated animals, while active metabolic rates were lowest in warm-acclimated frogs, likely reflecting compensation towards energy conservation. Evaporative water loss was not significantly altered by the acclimation treatments in either resting or active animals, indicating limited plasticity in this trait compared to metabolism. Our results suggest that plasticity of temperature limits and metabolism may benefit this species in variable environments such as those encountered in its expanded range. Lack of plasticity in water loss during resting and activity suggests that these frogs rely on their high cutaneous resistance and behavioural means to buffer climate variation. This study highlights the importance of synergistic interactions between physiology and behaviour in determining amphibian responses to temperature variation.

      PubDate: 2015-07-29T21:02:11Z
  • Starvation beneficially influences the liver physiology and nutrient
           metabolism in Edwardsiella tarda infected red sea bream (Pagrus major)
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Sipra Mohapatra, Tapas Chakraborty, Sonoko Shimizu, Shintaro Urasaki, Takahiro Matsubara, Yoshitaka Nagahama, Kohei Ohta
      Dietary compromises, especially food restrictions, possess species-specific effects on the health status and infection control in several organisms, including fish. To understand the starvation-mediated physiological responses in Edwardsiella tarda infected red sea bream, especially in the liver, we performed a 20-day starvation experiment using 4 treatment (2 fed and 2 starved) groups, namely, fed-placebo, starved-placebo, fed-infected, and starved-infected, wherein bacterial exposure was done on the 11th day. In the present study, the starved groups showed reduced hepatosomatic index and drastic depletion in glycogen storage and vacuole formation. The fed-infected fish showed significant (P<0.05) increase in catalase and superoxide dismutase activity in relation to its starved equivalent. Significant (P<0.05) alteration in glucose and energy metabolism, as evident from hexokinase and glucose-6-phosphate dehydrogenase activity, was recorded in the starved groups. Interestingly, coinciding with the liver histology, PPAR (peroxisome proliferator activated receptors) α transcription followed a time-dependent activation in starved groups while PPARγ exhibited an opposite pattern. The transcription of hepcidin 1 and transferrin, initially increased in 0dai (days after infection) starved fish but reduced significantly (P<0.05) at later stages. Two-color immunohistochemistry and subsequent cell counting showed significant increase in P63-positive cells at 0dai and 5dai but later reduced slightly at 10dai. Similar results were also obtained in the lysosomal (cathepsin D) and non-lysosomal (ubiquitin) gene transcription level. All together, our data suggest that starvation exerts multidirectional responses, which allows for better physiological adaptations during any infectious period, in red sea bream.

      PubDate: 2015-07-22T01:31:11Z
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