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BIOCHEMISTRY (222 journals)                  1 2     

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African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
American Journal of Biochemistry     Open Access   (Followers: 6)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 66)
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Annual Review of Biochemistry     Full-text available via subscription   (Followers: 49)
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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  
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Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 3)
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Biochemistry and Biophysics Reports     Open Access  
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Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 5)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 9)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
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Bit├ícora Digital     Open Access  
BMC Biochemistry     Open Access   (Followers: 14)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 7)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 5)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 4)
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Chemical and Biological Technologies for Agriculture     Open Access  
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Clinica Chimica Acta     Hybrid Journal   (Followers: 34)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 20)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 61)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
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: 7)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 9)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 4)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 21)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 6)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (Followers: 1)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
FABICIB     Open Access  
FEBS Letters     Hybrid Journal   (Followers: 58)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 4)
Food & Function     Full-text available via subscription   (Followers: 5)
Foundations of Modern Biochemistry     Full-text available via subscription  
Free Radicals and Antioxidants     Full-text available via subscription   (Followers: 3)
Frontiers in Molecular Biosciences     Open Access   (Followers: 2)
Frontiers in Natural Product Chemistry     Hybrid Journal  
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 9)
Green Chemistry     Full-text available via subscription   (Followers: 8)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 4)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 3)
Indian Journal of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Indonesian Biomedical Journal     Open Access  
Insect Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3)
International Journal of Biochemistry & Cell Biology     Hybrid Journal   (Followers: 6)
International Journal of Biochemistry and Biophysics     Open Access  
International Journal of Biological Chemistry     Open Access   (Followers: 4)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 5)
International Journal of Food Contamination     Open Access  
International Journal of Plant Physiology and Biochemistry     Open Access  
International Journal of Plant Research     Open Access   (Followers: 3)
International Journal of Secondary Metabolite     Open Access   (Followers: 1)
Invertebrate Immunity     Open Access   (Followers: 1)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 4)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 1)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 1)
Journal of Bioactive and Compatible Polymers     Hybrid Journal   (Followers: 2)
Journal of Biochemistry     Hybrid Journal   (Followers: 41)
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 174)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
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Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Chemical Biology     Hybrid Journal   (Followers: 1)
Journal of Chemical Neuroanatomy     Hybrid Journal  
Journal of Clinical Lipidology     Hybrid Journal   (Followers: 1)
Journal of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology     Hybrid Journal   (Followers: 3)
Journal of Drug Discovery and Therapeutics     Open Access   (Followers: 1)
Journal of Enzyme Inhibition and Medicinal Chemistry     Hybrid Journal   (Followers: 4)
Journal of Evolutionary Biochemistry and Physiology     Hybrid Journal  
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 3)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Investigational Biochemistry     Open Access   (Followers: 2)
Journal of Medical and Biomedical Sciences     Open Access  
Journal of Medical Biochemistry     Open Access   (Followers: 5)
Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
Journal of Molecular Biochemistry     Open Access   (Followers: 2)
Journal of Neurochemistry     Hybrid Journal   (Followers: 3)
Journal of Nutritional Biochemistry     Hybrid Journal   (Followers: 6)
Journal of Pediatric Biochemistry     Hybrid Journal   (Followers: 1)
Journal of Peptide Science     Hybrid Journal   (Followers: 24)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 1)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 5)
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 3)
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 7)
La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine     Hybrid Journal  
Marine Chemistry     Hybrid Journal   (Followers: 6)
Methods in Enzymology     Full-text available via subscription   (Followers: 11)
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Molecular inhibitors in targeted therapy     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
Mycology : An International Journal on Fungal Biology     Hybrid Journal   (Followers: 4)
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Plant Physiology and Biochemistry     Hybrid Journal   (Followers: 7)
Plasma Chemistry and Plasma Processing     Hybrid Journal   (Followers: 2)
Polymer Journal     Hybrid Journal   (Followers: 1)
Preparative Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)

        1 2     

Journal Cover Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2969 journals]
  • Examining the relationships between egg cortisol and oxidative stress in
           developing wild sockeye salmon (Oncorhynchus nerka)
    • Abstract: Publication date: Available online 15 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jessica J. Taylor, Natalie M. Sopinka, Samantha M. Wilson, Scott G. Hinch, David A. Patterson, Steven J. Cooke, William G. Willmore
      Maternally-derived hormones in oocytes, such as glucocorticoids (GCs), play a crucial role in embryo development in oviparous taxa. In fishes, maternal stressor exposure increases circulating and egg cortisol levels, the primary GC in fishes, as well as induces oxidative stress. Elevated egg cortisol levels modify offspring traits but whether maternal oxidative stress correlates with circulating and egg cortisol levels, and whether maternal/egg cortisol levels correlate with offspring oxidative stress have yet to be determined. The objective of this study was to examine the relationships among maternal and egg cortisol, and maternal and offspring oxidative stress to provide insight into the potential intergenerational effects of stressor exposure in sockeye salmon (Oncorhynchus nerka). Antioxidant concentration and oxidative stress were measured in maternal tissues (plasma, brain, heart and liver) as well as offspring developmental stages (pre-fertilization (PF), 24h post-fertilization, eyed, and hatch), and were compared to both naturally-occurring and experimentally-elevated (via cortisol egg bath) levels of cortisol in PF eggs. Oxygen radical absorptive capacity of tissues from maternal sockeye salmon was measured spectrophotometrically and was not correlated with maternal or PF egg cortisol concentrations. Also, naturally-occurring and experimentally-elevated cortisol levels in PF eggs (to mimic maternal stress) did not affect oxidative stress or antioxidant capacity of the offspring. We conclude that the metrics of maternal stress examined in sockeye salmon (i.e., maternal/egg cortisol, maternal oxidative stress) are independent of each other, and that egg cortisol content does not influence offspring oxidative stress.

      PubDate: 2016-06-18T18:34:03Z
  • Review: Linking physiology and biomineralization processes to ecological
           inferences on the life history of fishes
    • Abstract: Publication date: Available online 17 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): T.N. Loewen, B. Carriere, J.D. Reist, N.M. Halden, W.G. Anderson
      Biomineral chemistry is frequently used to infer life history events and habitat use in fishes; however, significant gaps remain in our understanding of the underlying mechanisms. Here we have taken a multidisciplinary approach to review the current understanding of element incorporation into biomineralized structures in fishes. Biominerals are primarily composed of calcium-based derivatives such as calcium carbonate found in otoliths and calcium phosphates found in scales, fins and bones. By focusing on non-essential life elements (strontium and barium) and essential life elements (calcium, zinc and magnesium), we attempt to connect several fields of study to synergise how physiology may influence biomineralization and subsequent inference of life history. Data provided in this review indicate that the presence of non-essential elements in biominerals of fish is driven primarily by hypo- and hyper-calcemic environmental conditions. The uptake kinetics between environmental calcium and its competing mimics define what is ultimately incorporated in the biomineral structure. Conversely, circannual hormonally driven variations likely influence essential life elements like zinc that are known to associate with enzyme function. Environmental temperature and pH as well as uptake kinetics for strontium and barium isotopes demonstrate the role of mass fractionation in isotope selection for uptake into fish bony structures. In consideration of calcium mobilisation, the action of osteoclast-like cells on calcium phosphates of scales, fins and bones likely plays a role in fractionation along with transport kinetics. Additional investigations into calcium mobilisation are warranted to understand differing views of strontium, and barium isotope fractionation between calcium phosphates and calcium carbonate structures in fishes.

      PubDate: 2016-06-18T18:34:03Z
  • Alterations in gene expression during fasting-induced atresia of early
           secondary ovarian follicles of coho salmon, Oncorhynchus kisutch
    • Abstract: Publication date: Available online 16 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Yoji Yamamoto, J. Adam Luckenbach, Graham Young, Penny Swanson
      Molecular processes that either regulate ovarian atresia or are consequences of atresia are poorly understood in teleost fishes. We hypothesized that feed restriction that perturbs normal ovarian growth and induces follicular atresia would alter ovarian gene expression patterns. Previtellogenic, two-year old coho salmon (Oncorhynchus kisutch) were subjected to prolonged fasting to induce atresia or maintained on a normal feeding schedule that would promote continued ovarian development. To identify genes that were specifically up- or down-regulated during oocyte growth in healthy, growing fish compared to fasted fish, reciprocal suppression subtractive hybridization (SSH) cDNA libraries were generated using ovaries from fed and fasted animals. Differential expression of genes identified by SSH was confirmed with quantitative PCR. The SSH library representing genes elevated in ovaries of fed fish relative to those of fasted fish contained steroidogenesis-related genes (e.g., hydroxy-delta-5-steroid dehydrogenase), Tgf-beta superfamily members (e.g., anti-Mullerian hormone) and cytoskeletal intermediate filament proteins (e.g., type I keratin s8). Overall, these genes were associated with steroid production, cell proliferation and differentiation, and ovarian epithelialization. The library representing genes elevated in ovaries of fasted fish relative to fed fish contained genes associated with apoptosis (e.g., programmed cell death protein 4), cortical alveoli (e.g., alveolin), the zona pellucida (e.g., zona pellucida protein c), and microtubules (e.g., microtubule associated protein tau). Elevated expression of this suite of genes was likely associated with the initiation of atresia and/or a reduced rate of follicle development in response to fasting. This study revealed ovarian genes involved in normal early secondary oocyte growth and potential early markers of atresia.

      PubDate: 2016-06-18T18:34:03Z
  • Duplicated CFTR isoforms in eels diverged in regulatory structures and
           osmoregulatory functions
    • Abstract: Publication date: Available online 17 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marty Kwok-Shing Wong, Supriya Pipil, Akira Kato, Yoshio Takei
      Two cystic fibrosis transmembrane conductance regulator (CFTR) isoforms, CFTRa and CFTRb, were cloned in Japanese eel and their structures and functions were studied in different osmoregulatory tissues in freshwater (FW) and seawater (SW) eels. Molecular phylogenetic results suggested that the CFTR duplication in eels occurred independently of the duplication event in salmonid. CFTRa was expressed in the intestine and kidney and downregulated in both tissues in SW eels, while CFTRb was specifically expressed in the gill and greatly upregulated in SW eels. Structurally, the CFTR isoforms are similar in most functional domains except the regulatory R domain, where the R domain of CFTRa is similar to that of human CFTR but the R domain of CFTRb is unique in having high intrinsic negative charges and fewer phosphorylation sites, suggesting divergence of isoforms in terms of gating properties and hormonal regulation. Immunohistochemical results showed that CFTR was localized on the apical regions of SW ionocytes, suggesting a Cl− secretory role as in other teleosts. In intestine and kidney, however, immunoreactive CFTR was mostly found in the cytosolic vesicles in FW eels, indicating that Cl− channel activity could be low at basal conditions, but could be rapidly increased by membrane insertion of the stored channels. Guanylin (GN), a known hormone that increases CFTR activity in mammalian intestine, failed to redistribute CFTR and to affect its expression in eel intestine. The results suggested that GN-independent CFTR regulation is present in eel intestine and kidney.

      PubDate: 2016-06-18T18:34:03Z
  • Oxidative stress in aquatic ecosystems: Selected papers from the Second
           International Conference
    • Abstract: Publication date: Available online 11 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Joanna Joyner-Matos, Doris Abele, José Pablo Vázquez Medina, Tania Zenteno-Savín

      PubDate: 2016-06-14T04:42:22Z
  • Acclimation temperature alters the relationship between growth and
           swimming performance among juvenile common carp (Cyprinus carpio)
    • Abstract: Publication date: Available online 13 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Xu Pang, Shi-Jian Fu, Yao-Guang Zhang
      Individual variation in growth, metabolism and swimming performance, their possible interrelationships, and the effects of temperature were investigated in 30 juvenile common carp (Cyprinus carpio) at two acclimation temperatures (15 and 25°C). We measured body mass, critical swimming speed (U crit), resting metabolic rate (RMR), active metabolic rate (AMR) and metabolic scope (MS) twice (28days apart) in both temperature groups. Fish acclimated to 25°C showed a 204% higher specific growth rate (SGR) than those acclimated to 15°C due to a 97% higher feeding rate (FR) and a 46% higher feed efficiency (FE). Among individuals, SGR was positively correlated with the FR and FE at both low and high temperatures. All measured variables (U crit, RMR and AMR) related to swimming except MS showed a high repeatability after adjusting for body mass (mass-independent). Fish acclimated to 25°C had a 40% higher U crit compared with 15°C acclimated fish, which was at least partially due to an improved metabolic capacity. AMR showed a 97% increase, and MS showed a 104% parallel increase with the higher acclimation temperature. Residual (mass-independent) U crit was positively correlated with residual RMR, AMR and MS, except for the residual RMR at high temperature. When acclimated to the lower temperature, both the residual and absolute U crit were negatively correlated with FR and FE and, hence, with SGR, suggesting a functional trade-off between growth and locomotion in fish acclimated to low temperatures. However, when acclimated to the higher temperature, this trade-off no longer existed; absolute U crit was positively correlated with SGR because individuals with rapid growth exhibited greatly increased body mass. The higher metabolic capacity at 25°C showed a positive effect on both swimming performance and growth rate (because of improved digestive efficiency) under the high-temperature condition, which we did not anticipate. Overall, these results indicate that temperature alters the relationship between growth and swimming performance of juvenile common carp. This change may be an adaptive strategy to seasonal temperature variation during their life history.

      PubDate: 2016-06-14T04:42:22Z
  • Role of Halloween genes in ecdysteroids biosynthesis of the swimming crab
           (Portunus trituberculatus): Implications from RNA interference and
           eyestalk ablation
    • Abstract: Publication date: Available online 4 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Xi Xie, Zhiye Liu, Mingxin Liu, Tian Tao, Xiquan Shen, Dongfa Zhu
      Molting, including metamorphosis molting in arthropods are controlled by the ecdysteroids that are synthesized and secreted by the crustacean Y-organ (YO) or the insect prothoracic gland (PG). The Halloween genes encoding the enzymes mainly involved in the biosynthesis of ecdysteroids are well studied in insects but not in crustaceans. Given the importance of Halloween genes in ecdysteroids biosynthesis, we have previously reported the cDNA cloning of disembodied (Dib) in P. trituberculatus. Here, cDNA sequences of another two Halloween genes, Spook (Spo) and Shadow (Sad), were further identified and characterized. The predicted amino acid sequences for these two Halloween genes of Portunus trituberculatus were compared to those of several other arthropods, and several typical domains of the cytochrome P450 mono-oxygenase (CYP) were identified. Similar to the tissue distribution of Dib, the Spo and Sad also showed high specificity to the YO. RNA interference (RNAi) of these 3 genes indicated they all play essential role in ecdysteroids biosynthesis. To investigate the relationships of the Halloween genes to the eyestalk neuropeptides such as molt-inhibiting hormone (MIH), effects of eyestalk ablation (ESA) on the expression of Dib, Spo and Sad were detected. Expression of Dib and Sad, but not Spo, was significantly induced by ESA. The result indicated that the inhibition of MIH in ecdysteroids biosynthesis may be partly through the transcriptional regulation of certain Halloween genes, such as Dib and Sad, while the Spo might not be the target for MIH signal.

      PubDate: 2016-06-08T04:14:24Z
  • Corrigendum to “Plasma leptin, glucose and non-esterified fatty acid
           variations in dromedary camels exposed to prolonged periods of
           underfeeding or dehydration” [Comp. Biochem. Physiol., A 166 (2013)
    • Abstract: Publication date: Available online 3 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Carole Delavaud, Mohammed Bengoumi, Bernard Faye, Didier Levieuxe, Yves Chilliard

      PubDate: 2016-06-08T04:14:24Z
  • Editorial Board
    • Abstract: Publication date: June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 196

      PubDate: 2016-06-03T02:49:32Z
  • The liquorice root derivative glycyrrhetinic acid can ameliorate
           ionoregulatory disturbance in rainbow trout (Oncorhynchus mykiss) abruptly
           exposed to ion-poor water
    • Abstract: Publication date: Available online 21 May 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chun Chih Chen, Dennis Kolosov, Scott P. Kelly
      To consider the idea that a dietary botanical supplement could act as an adaptogen in a teleost fish, the effect of a liquorice root derivative (18β-glycyrrhetinic acid, 18βGA) on rainbow trout following an acute ionoregulatory stressor was examined. Freshwater (FW) trout were fed a control or 18βGA supplemented diet (0, 5, or 50μg 18βGA/g diet) for 2weeks, then abruptly exposed to ion-poor water (IPW) for 24h. Following IPW exposure, muscle moisture content and serum cortisol levels elevated and serum [Na+] and/or [Cl−] reduced in control and 50μg/g 18βGA-fed fish. However, these endpoints were unaltered in 5μg/g 18βGA-fed fish. Gill tissue was investigated for potential mechanisms of 18βGA action by examining mRNA abundance of genes encoding corticosteroid receptors (CRs), 11β-hydroxysteroid dehydrogenase 2 (11β-hsd2), and tight junction (TJ) proteins, as well as Na+-K+-ATPase and H+-ATPase activity, and mitochondrion-rich cell (MRC) morphometrics. Following IPW exposure, CR and 11β-hsd2 mRNA, MRC fractional surface, Na+-K+-ATPase and H+-ATPase activity were unaltered or decreased in 50μg 18βGA fish, as was mRNA encoding select TJ proteins. In contrast, 5μg 18βGA-fed fish exhibited elevated 11β-hsd2 and CR mRNA abundance versus 50μg 18βGA-fed, and reduced MRC apical area as well as some differences in TJ protein mRNA abundance versus control fish. Data suggest that 18βGA, at low levels, may be adaptogenic in trout and might help to ameliorate ionoregulatory perturbation following IPW exposure. This seems to occur, in part, through 18βGA-induced alterations in the biochemistry and physiology of the gill.

      PubDate: 2016-06-03T02:49:32Z
  • Orexin-A stimulates the expression of GLUT4 in a glucose dependent manner
           in the liver of orange-spotted grouper (Epinephelus coioides)
    • Abstract: Publication date: Available online 2 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Cong Zhang, Caiyun Sun, Bin Wang, Peipei Yan, Amin Wu, Guokun Yang, Wensheng Li
      Orexins are hypothalamic neuropeptides involved in the central regulation of feeding behavior, sleep-wake cycle and other physiological functions. Orexin-A can regulate energy metabolism and increase glucose uptake, suggesting a role in glucose metabolism. In this study, we investigated the effects of orexin-A on GLUT4 mRNA and protein levels and the intracellular signaling mechanisms mediating orexin-A activity in the hepatocytes of grouper. Our results demonstrate that intraperitoneal injection of orexin-A increased the expression of GLUT4 in the liver, and this effect was significantly enhanced by co-injection of glucose. Treatment of primary cultured hepatocytes with either orexin-A or glucose alone had no effect on the expression of GLUT4, while co-treatment with orexin-A and glucose significantly increased the expression of GLUT4. This stimulatory effect was partially blocked by inhibitors to ERK1/2, JNK or p38 MAPK and was further blocked by an orexin receptor antagonist, which indicates that orexin-A could stimulate the expression of GLUT4 in a glucose dependent manner in primary hepatocytes via ERK1/2, JNK and p38 signaling. Our results suggest that orexin-A could play a pivotal role in stimulating glucose utilization in grouper, for a long-term goal, which might be useful in reducing costs in the aquaculture industry.

      PubDate: 2016-06-03T02:49:32Z
  • Editorial Board
    • Abstract: Publication date: July 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 197

      PubDate: 2016-06-03T02:49:32Z
  • Measurement of flying and diving metabolic rate in wild animals: review
           and recommendations
    • Abstract: Publication date: Available online 3 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kyle H. Elliott
      Animals’ abilities to fly long distances and dive to profound depths fascinate earthbound researchers. Due to the difficulty of making direct measurements during flying and diving, many researchers resort to modeling so as to estimate metabolic rate during each of those activities in the wild, but those models can be inaccurate. Fortunately, the miniaturization, customization and commercialization of biologgers has allowed researchers to increasingly follow animals on their journeys, unravel some of their mysteries and test the accuracy of biomechanical models. I provide a review of the measurement of flying and diving metabolic rate in the wild, paying particular attention to mass loss, doubly-labelled water, heart rate and accelerometry. Biologgers can impact animal behavior and influence the very measurements they are designed to make, and I provide seven guidelines for the ethical use of biologgers. If biologgers are properly applied, quantification of metabolic rate across a range of species could produce robust allometric relationships that could then be generally applied. As calibrating techniques for measuring flying and diving metabolic rate in captivity is difficult, I suggest that applying multiple techniques in the field to reinforce one another may be a viable alternative. The coupling of multi-sensor biologgers with biomechanical modeling promises to provide great improved precision in the measurement of flying and diving metabolic rate in wild animals.

      PubDate: 2016-06-03T02:49:32Z
  • Oxygen concentration affects upper thermal tolerance in a terrestrial
    • Abstract: Publication date: Available online 2 June 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Tanner K. Shea, P. Mason DuBois, Natalie M. Claunch, Nicolette E. Murphey, Kiley A. Rucker, Robert A. Brewster, Emily N. Taylor
      We tested the oxygen limitation hypothesis, which states that animals decline in performance and reach the upper limits of their thermal tolerance when the metabolic demand for oxygen at high temperatures exceeds the circulatory system's ability to supply adequate oxygen, in air-breathing lizards exposed to air with different oxygen concentrations. Lizards exposed to hypoxic air (6% O2) gaped, panted, and lost their righting response at significantly lower temperatures than lizards exposed to normoxic (21% O2) or hyperoxic (35% O2) air. A greater proportion of lizards in the hyperoxic treatment were able to withstand body temperatures above 44°C than in the normoxic treatment. We also found that female lizards had a higher panting threshold than male lizards, while sex had no effect on gaping threshold and loss of righting response. Body size affected the temperature at which lizards lost the righting response, with larger lizards losing the response at lower temperatures than smaller lizards when exposed to hypoxic conditions. These data suggest that oxygen limitation plays a mechanistic role in the thermal tolerance of lizards.

      PubDate: 2016-06-03T02:49:32Z
  • Effects of feed restriction on the upper temperature tolerance and heat
           shock response in juvenile green and white sturgeon
    • Abstract: Publication date: August 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 198
      Author(s): Seunghyung Lee, Silas S.O. Hung, Nann A. Fangue, Liran Haller, Christine E. Verhille, Juan Zhao, Anne E. Todgham
      The objective of the current study was to investigate the effects of feed restriction on whole-organism upper thermal tolerance and the heat shock response of green and white sturgeon to determine how changes in food amount might influence physiological performance of each species when faced with temperature stress. Two parallel feed restriction trials were carried out for juvenile green (202g; 222-day post hatch: dph) and white sturgeon (205g; 197-dph) to manipulate nutritional status at 12.5%, 25%, 50%, or 100% of optimum feeding rate (100% OFR were 1.6% and 1.8% body weight/day, respectively) for four weeks. Following the trials, the critical thermal maximum (CTMax, 0.3°C/min) of sturgeon (N =12/treatment/species) was assessed as an indicator of whole-organism upper thermal tolerance. To assess temperature sensitivity, sturgeon (N =9/treatment/species) were acutely transferred to two temperature treatments (28°C and 18°C as a handling control) for 2h followed by 2h of recovery at 18°C before being sacrificed, and gill, brain, and mucus sampled for measurements of 70-kDa heat shock protein levels (Hsc/Hsp70). Feeding rate had species-specific effects on CTMax in green and white sturgeon such that CTMax of green sturgeon decreased as the magnitude of feed restriction increased; whereas, CTMax of white sturgeon did not change with feed restriction. Elevated temperature (28°C) and feed restriction increased Hsc/Hsp70 levels in the gill tissue of green sturgeon, while heat shock increased Hsc/Hsp70 levels in the mucus of white sturgeon. Our results suggest that green sturgeon may be more susceptible to temperature stress under food-limited conditions.

      PubDate: 2016-06-03T02:49:32Z
  • A comparative study of vitellogenesis in Echinodermata: Lessons from the
           sea star
    • Abstract: Publication date: August 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 198
      Author(s): Khalid M. Alqaisi, Miles D. Lamare, Dave R. Grattan, Erin L. Damsteegt, Wolfgang J. Schneider, P. Mark Lokman
      The provision of yolk precursor proteins to the oviparous egg is crucial for normal embryo development. In Echinodermata, a transferrin-like yolk component termed major yolk protein (MYP) is a major precursor protein in Echinoidea and Holothuroidea. In contrast, in Asteroidea a single vitellogenin (Vtg) was recently identified, but its role as primary yolk protein remains unclear. To resolve the apparent MYP-Vtg dichotomy in sea stars and to understand the dynamics of candidate yolk protein gene expression during the reproductive cycle, we investigated the molecular structures of sea star Vtg and MYP and quantified their transcript levels during oogenesis. By combining protein sequencing of the predominant proteins in ovulated eggs of Patiriella regularis with ovarian transcriptome sequencing and molecular cloning, we characterized two cDNAs encoding two bona fide Vtgs (PrVtg1 and PrVtg2) and a partial cDNA encoding MYP (PrMYP). PrMYP mRNA was found in low abundance in growing oocytes, possibly as maternal transcripts for translation after ovulation. In contrast, PrVtg transcripts, whose levels varied during the reproductive cycle, were not found in developing oocytes – rather, they were detected in ovarian follicle cells and pyloric caeca, indicating an extra-oocytic origin. Vtg accumulating in oocytes was stored in the form of cleaved products, which constituted the most abundant yolk polypeptides in ovulated sea star eggs; their levels decreased during early embryonic and larval development. Together, these traits are the hallmarks of a classical yolk protein – and hence, we contend that Vtg, and not MYP, is the main yolk protein in asteroids.

      PubDate: 2016-06-03T02:49:32Z
  • Interspecific and environment-induced variation in hypoxia tolerance in
    • Abstract: Publication date: August 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 198
      Author(s): Brittney G. Borowiec, Kyle D. Crans, Fariborz Khajali, Nicole A. Pranckevicius, Alexander Young, Graham R. Scott
      Hypoxia tolerance is a plastic trait, and can vary between species. We compared hypoxia tolerance (hypoxic loss of equilibrium, LOE, and critical O2 tension, Pcrit) and traits that dictate O2 transport and metabolism in pumpkinseed (Lepomis gibbosus), bluegill (L. macrochirus), and the naturally occurring hybrid in different acclimation environments (wild versus lab-acclimated fish) and at different temperatures. Wild fish generally had lower Pcrit and lower PO2 at LOE in progressive hypoxia than lab-acclimated fish, but time to LOE in sustained hypoxia (PO2 of 2kPa) did not vary between environments. Wild fish also had greater gill surface area and higher haematocrit, suggesting that increased O2 transport capacity underlies the environmental variation in Pcrit. Metabolic (lactate dehydrogenase, LDH; pyruvate kinase, PK; citrate synthase; cytochrome c oxidase) and antioxidant (catalase and superoxide dismutase) enzyme activities varied appreciably between environments. Wild fish had higher protein contents across tissues and higher activities of LDH in heart, PK in brain, and catalase in brain, liver, and skeletal muscle. Otherwise, wild fish had lower activities for most enzymes. Warming temperature from 15 to 25°C increased O2 consumption rate, Pcrit, PO2 at LOE, and haemoglobin-O2 affinity, and decreased time to LOE, but pumpkinseed had ≥2-fold longer time to LOE than bluegill and hybrids across this temperature range. This was associated with higher LDH activities in the heart and muscle, and lower or similar antioxidant enzyme activities in several tissues. However, the greater hypoxia tolerance of pumpkinseed collapsed at 28°C, demonstrating that the interactive effects of hypoxia and warming temperature can differ between species. Overall, distinct mechanisms appear to underpin interspecific and environment-induced variation in hypoxia tolerance in sunfish.

      PubDate: 2016-06-03T02:49:32Z
  • Editorial Board
    • Abstract: Publication date: August 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 198

      PubDate: 2016-06-03T02:49:32Z
  • Sodium affects the sperm motility in the European eel
    • Abstract: Publication date: August 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 198
      Author(s): M. Carmen Vílchez, Marina Morini, David S. Peñaranda, Víctor Gallego, Juan F. Asturiano, Luz Pérez
      The role of seminal plasma sodium and activation media sodium on sperm motility was examined by selectively removing the element from these two media, in European eel sperm. Sperm size (sperm head area) was also measured using an ASMA (Automated Sperm Morphometry Analyses) system, in the different conditions. Intracellular sodium [Na+]i was quantitatively analyzed by first time in the spermatozoa from a marine fish species. Measurement of [Na+]i was done before and after motility activation, by Flow Cytometry, using CoroNa Green AM as a dye. Sperm motility activation induced an increase in [Na+]i, from 96.72mM in quiescent stage to 152.21mM post-activation in seawater. A significant decrease in sperm head area was observed post-activation in seawater. There was a notable reduction in sperm motility when sodium was removed from the seminal plasma, but not when it was removed from the activation media. Sodium removal was also linked to a significant reduction in sperm head area in comparison to the controls. Our results indicate that the presence of the ion Na+ in the seminal plasma (or in the extender medium) is necessary for the preservation of sperm motility in European eel, probably because it plays a role in maintaining an appropriate sperm cell volume in the quiescent stage of the spermatozoa.

      PubDate: 2016-06-03T02:49:32Z
  • Regulation of gill claudin paralogs by salinity, cortisol and prolactin in
           Mozambique tilapia (Oreochromis mossambicus)
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Christian K. Tipsmark, Jason P. Breves, D. Brett Rabeneck, Rebecca T. Trubitt, Darren T. Lerner, E. Gordon Grau
      In euryhaline teleosts, reorganization of gill tight junctions during salinity acclimation involves dynamic expression of specific claudin (Cldn) paralogs. We identified four transcripts encoding Cldn tight junction proteins in the tilapia gill transcriptome: cldn10c, cldn10e, cldn28a and cldn30. A tissue distribution experiment found cldn10c and cldn10e expression levels in the gill to be 100-fold higher than any other tissues examined. cldn28a and cldn30 levels in the gill were 10-fold greater than levels in other tissues. Expression of these genes in Mozambique tilapia was examined during acclimation to fresh water (FW), seawater (SW), and in response to hormone treatments. Transfer of tilapia from FW to SW elevated cldn10c and cldn10e, while cldn28a and cldn30 were stimulated following transfer from SW to FW. In hypophysectomized tilapia transferred to FW, pituitary extirpation induced reduced expression of cldn10c, cldn10e and cldn28a; these effects were mitigated equally by either prolactin or cortisol replacement. In vitro experiments with gill filaments showed that cortisol stimulated expression of all four cldns examined, suggesting a direct action of cortisol in situ. Our data indicate that elevated cldn10c and cldn10e expression is important during acclimation of tilapia to SW possibly by conferring ion specific paracellular permeability. On the other hand, expression of cldn28a and cldn30 appears to contribute to reorganization of branchial epithelium during FW acclimation. Hormone treatment experiments showed that particular FW- and SW-induced cldns are controlled by cortisol and prolactin.

      PubDate: 2016-06-03T02:49:32Z
  • Iron transport across the skin and gut epithelia of Pacific hagfish:
           Kinetic characterisation and effect of hypoxia
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Chris N. Glover, Som Niyogi, Tamzin A. Blewett, Chris M. Wood
      In most animals, the acquisition of the essential trace metal iron (Fe) is achieved by the gut, but in hagfishes, the skin is a nutrient absorbing epithelium, and thus may also play a role in Fe uptake. In the current study, the absorption of Fe, as Fe(II), across the intestinal and cutaneous epithelia of Pacific hagfish (Eptatretus cirrhatus) was investigated. Both epithelia absorbed Fe, with saturation at lower tested concentrations, superseded by a diffusive component at higher Fe exposure concentrations. Affinity constants (Km) of 9.4 and 137μM, and maximal Fe transport rates (Jmax) of 0.81 and 0.57nmolcm−2 h−1 were determined for the skin and the gut, respectively. This characterises the skin as a relatively high-affinity Fe transport epithelium. The majority of the absorbed Fe in the skin remained in the tissue, whereas in the gut, most absorbed Fe was found in the serosal fluid, suggesting distinct mechanisms of Fe handling between the two epithelia. To determine if reduced dissolved oxygen altered Fe transport, hagfish were subjected to hypoxia for 24h, before Fe transport was again assessed. Hypoxia had no effect on Fe transport across gut or skin, likely owing to the relative lack of change in haematological variables, and thus an unaltered Fe demand under such conditions. These data are the first to kinetically characterise the absorption of a nutritive trace metal across the epithelia of hagfish and add to the growing understanding of the role of the skin in nutritive transport in this group.

      PubDate: 2016-06-03T02:49:32Z
  • Fasting-induced daily torpor in desert hamsters (Phodopus roborovskii)
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Qing-Sheng Chi, Xin-Rong Wan, Fritz Geiser, De-Hua Wang
      Daily torpor is frequently expressed in small rodents when facing energetically unfavorable ambient conditions. Desert hamsters (Phodopus roborovskii, ~20g) appear to be an exception as they have been described as homeothermic. However, we hypothesized that they can use torpor because we observed reversible decreases of body temperature (Tb) in fasted hamsters. To test this hypothesis we (i) randomly exposed fasted summer-acclimated hamsters to ambient temperatures (Tas) ranging from 5 to 30°C or (ii) supplied them with different rations of food at Ta 23°C. All desert hamsters showed heterothermy with the lowest mean Tb of 31.4±1.9°C (minimum, 29.0°C) and 31.8±2.0°C (minimum, 29.0°C) when fasted at Ta of 23°C and 19°C, respectively. Below Ta 19°C, the lowest Tb and metabolic rate increased and the proportion of hamsters using heterothermy declined. At Ta 5°C, nearly all hamsters remained normothermic by increasing heat production, suggesting that the heterothermy only occurs in moderately cold conditions, perhaps to avoid freezing at extremely low Tas. During heterothermy, Tbs below 31°C with metabolic rates below 25% of those during normothermia were detected in four individuals at Ta of 19°C and 23°C. Consequently, by definition, our observations confirm that fasted desert hamsters are capable of shallow daily torpor. The negative correlation between the lowest Tbs and amount of food supply shows that heterothermy was mainly triggered by food shortage. Our data indicate that summer-acclimated desert hamsters can express fasting-induced shallow daily torpor, which may be of significance for energy conservation and survival in the wild.

      PubDate: 2016-06-03T02:49:32Z
  • Selenoprotein M gene expression, peroxidases activity and hydrogen
           peroxide concentration are differentially regulated in gill and
           hepatopancreas of the white shrimp Litopenaeus vannamei during hypoxia and
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Antonio García-Triana, Alma Beatriz Peregrino-Uriarte, Gloria Yepiz-Plascencia
      In many organisms, episodes of low O2 concentration (hypoxia) and the subsequent rise of O2 concentration (reoxygenation) result in the accumulation of reactive oxygen species and oxidative stress. Selenoprotein M (SelM), is a selenocysteine containing protein with redox activity involved in the antioxidant response. It was previously shown that in the white shrimp Litopenaeus vannamei, the silencing of SelM by RNAi decreased peroxidase activity in gill. In this work, we report the structure of the SelM gene (LvSelM) and its relative expression in hepatopancreas and gill after 24h of hypoxia followed by 1h of reoxygenation. The gene is composed by four exons interrupted by tree introns. In gills and hepatopancreas, SelM expression increased after 24h of hypoxia followed by 1h of reoxygenation, while peroxidases activity diminished in hepatopancreas but increased in gills. Hydrogen peroxide (H2O2) concentration was higher in hepatopancreas in response to hypoxia for 6h and did not change after 24 of hypoxia followed by reoxygenation; conversely, no change was detected in gill. SelM appears to be a key enzyme in gill oxidative stress regulation, since the higher expression is associated with an increase in peroxidases activity while maintaining H2O2 concentration. In contrast, in hepatopancreas there is a higher expression after hypoxia and reoxygenation for 24h, but peroxidases activity was lower and the change in H2O2 occurred after 6h of hypoxia and this level was maintained during reoxygenation.

      PubDate: 2016-06-03T02:49:32Z
  • Effects of thermal increase on aerobic capacity and swim performance in a
           tropical inland fish
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Laura H. McDonnell, Lauren J. Chapman
      Rising water temperature associated with climate change is increasingly recognized as a potential stressor for aquatic organisms, particularly for tropical ectotherms that are predicted to have narrow thermal windows relative to temperate ectotherms. We used intermittent flow resting and swimming respirometry to test for effects of temperature increase on aerobic capacity and swim performance in the widespread African cichlid Pseudocrenilabrus multicolor victoriae, acclimated for a week to a range of temperatures (2°C increments) between 24 and 34°C. Standard metabolic rate (SMR) increased between 24 and 32°C, but fell sharply at 34°C, suggesting either an acclimatory reorganization of metabolism or metabolic rate depression. Maximum metabolic rate (MMR) was elevated at 28 and 30°C relative to 24°C. Aerobic scope (AS) increased between 24 and 28°C, then declined to a level comparable to 24°C, but increased dramatically 34°C, the latter driven by the drop in SMR in the warmest treatment. Critical swim speed (Ucrit) was highest at intermediate temperature treatments, and was positively related to AS between 24 and 32°C; however, at 34°C, the increase in AS did not correspond to an increase in Ucrit, suggesting a performance cost at the highest temperature.

      PubDate: 2016-06-03T02:49:32Z
  • Synchronization to light and mealtime of the circadian rhythms of
           self-feeding behavior and locomotor activity of white shrimps (Litopenaeus
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Aline Dos Anjos Santos, José Fernando López-Olmeda, Francisco Javier Sánchez-Vázquez, Rodrigo Fortes-Silva
      The role of light and feeding cycles in synchronizing self-feeding and locomotor activity rhythms was studied in white shrimps using a new self-feeding system activated by photocell trigger. In experiment 1, shrimps maintained under a 12:12h light/dark (LD) photoperiod were allowed to self-feed using feeders connected to a photoelectric cell, while locomotor activity was recorded with a second photocell. On day 30, animals were subjected to constant darkness (DD) for 12days to check the existence of endogenous circadian rhythms. In the experiment 2, shrimps were exposed to both a 12:12h LD photoperiod and a fixed meal schedule in the middle of the dark period (MD, 01:00h). On day 20, shrimps were exposed to DD conditions and the same fixed feeding. On day 30, they were maintained under DD and fasted for 7days. The results revealed that under LD, shrimps showed a clear nocturnal feeding pattern and locomotor activity (81.9% and 67.7% of total daily food-demands and locomotor activity, respectively, at nighttime). Both feeding and locomotor rhythms were endogenously driven and persisted under DD with an average period length (τ) close to 24h (circadian) (τ=24.18±0.13 and 23.87±0.14h for locomotor and feeding, respectively). Moreover, Shrimp showed a daily food intake under LD condition (1.1±0.2gday−1 in the night phase vs. 0.2±0.1gday−1 in the light phase). Our findings might be relevant for some important shrimp aquaculture aspects, such as developing suitable feeding management on shrimp farms.

      PubDate: 2016-06-03T02:49:32Z
  • Characterization of heat shock cognate protein 70 gene and its
           differential expression in response to thermal stress between two wing
           morphs of Nilaparvata lugens (Stål)
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Kai Lu, Xia Chen, Wenting Liu, Qiang Zhou
      Previous studies have demonstrated differences in thermotolerance between two wing morphs of Nilaparvata lugens, the most serious pest of rice across the Asia. To reveal the molecular regulatory mechanisms underlying the differential thermal resistance abilities between two wing morphs, a full-length of transcript encoding heat shock cognate protein 70 (Hsc70) was cloned, and its expression patterns across temperature gradients were analyzed. The results showed that the expression levels of NlHsc70 in macropters increased dramatically after heat shock from 32 to 38°C, while NlHsc70 transcripts in brachypters remained constant under different temperature stress conditions. In addition, NlHsc70 expression in the macropters was significantly higher than that in brachypters at 1 and 2h recovery from 40°C heat shock. There was no significant difference in NlHsc70 mRNA expression between brachypters and macropters under cold shock conditions. Therefore, NlHsc70 was indeed a constitutively expressed member of the Hsp70 family in brachypters of N. lugens, while it was heat-inducible in macropters. Furthermore, the survival rates of both morphs injected with NlHsc70 dsRNA were significantly decreased following heat shock at 40°C or cold shock at 0°C for 1h. These results suggested that the up-regulation of NlHsc70 is possibly related to the thermal resistance, and the more effective inducement expression of NlHsc70 in macropters promotes a greater thermal tolerance under temperature stress conditions.

      PubDate: 2016-06-03T02:49:32Z
  • Is the kisspeptin system involved in responses to food restriction in
           order to preserve reproduction in pubertal male sea bass (Dicentrarchus
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Sebastián Escobar, Alicia Felip, Silvia Zanuy, Manuel Carrillo
      Previous works on European sea bass have determined that long-term exposure to restrictive feeding diets alters the rhythms of some reproductive/metabolic hormones, delaying maturation and increasing apoptosis during gametogenesis. However, exactly how these diets affect key genes and hormones on the brain–pituitary–gonad (BPG) axis to trigger puberty is still largely unknown. We may hypothesize that all these signals could be integrated, at least in part, by the kisspeptin system. In order to capture a glimpse of these regulatory mechanisms, kiss1 and kiss2 mRNA expression levels and those of their kiss receptors (kiss1r, kiss2r) were analyzed in different areas of the brain and in the pituitary of pubertal male sea bass during gametogenesis. Furthermore, other reproductive hormones and factors as well as the percentage of males showing full spermiation were also analyzed. Treated fish fed maintenance diets provided evidence of overexpression of the kisspeptin system in the main hypophysiotropic regions of the brain throughout the entire sexual cycle. Conversely, Gnrh1 and gonadotropin pituitary content and plasma sexual steroid levels were downregulated, except for Fsh levels, which were shown to increase during spermiation. Treated fish exhibited lower rates of spermiation as compared to control group and a delay in its accomplishment. These results demonstrate how the kisspeptin system and plasma Fsh levels are differentially affected by maintenance diets, causing a retardation, but not a full blockage of the reproductive process in the teleost fish European sea bass. This suggests that a hormonal adaptive strategy may be operating in order to preserve reproductive function in this species.

      PubDate: 2016-06-03T02:49:32Z
  • Digestive efficiencies of Cape white-eyes (Zosterops virens), red-winged
           starlings (Onychognathus morio) and speckled mousebirds (Colius striatus)
           fed varying concentrations of equicaloric glucose or sucrose artificial
           fruit diets
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Manqoba M. Zungu, Colleen T. Downs
      Digestive physiology is important for understanding the feeding behaviour of organisms. Specifically, studies on the digestive physiology of frugivorous and nectarivorous birds are important for elucidating their preference patterns in the wild and the selective pressures they exert on fruit pulp and nectar. In this study, digesta transit times and digestive efficiencies of three species of birds, the Cape white-eyes (Zosterops virens), red-winged starlings (Onychognathus morio) and speckled mousebirds (Colius striatus) were investigated on equicaloric glucose or sucrose artificial fruit diets. Three concentrations, approximating the natural range of sugar concentrations in sugary, bird-dispersed fruits were used: low (6.6%), medium (12.4%) and high (22%). Digesta transit times of birds increased with an increase in concentration for all diets but were generally higher on glucose diets. Intake rates, on the other hand, decreased with an increase in sugar concentration. All species of birds failed to maintain a constant assimilated energy intake on glucose diets but mousebirds and white-eyes maintained it on sucrose diets. Apparent assimilation efficiencies of glucose diets for all species were comparable and typical of those found in other frugivorous birds. However, assimilation efficiencies for sucrose diets differed widely with red-winged starlings displaying very low assimilation efficiencies and as a consequence; they lost significant body mass on all sucrose diets. These results demonstrate the importance of digestive physiology in explaining fruit selection patterns in frugivorous birds and how a seemingly trivial physiological trait can have dire ecological consequences.

      PubDate: 2016-06-03T02:49:32Z
  • Functional characterization of insulin-like growth factors in an ancestral
           fish species, the Shovelnose sturgeon Scaphirhynchus platorhynchus
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Carlin M. Fenn, Jacob W. Bledsoe, Brian C. Small
      Observations from the present study provide the first characterization of the GH-IGF axis in Shovelnose sturgeon Scaphirhynchus platorhynchus, an ancestral fish species. An initial characterization of steady-state IGF-I and IGF-II gene expression in multiple tissues was conducted using real-time RT-qPCR. Overall, the tissues had significantly different profiles of IGF-I gene expression, with the highest IGF-I expression observed in the liver. The highest IGF-II gene expression was also observed in the liver, with minimal or no detection in muscle. A comparison between IGF-I and IGF-II expression within individual tissues revealed higher levels of IGF-II than IGF-I mRNA in the spleen, stomach and trunk kidney, and higher levels of relative IGF-I mRNA expression in the intestine and muscle. The GH-IGF axis was further elucidated by observing the effects of exogenous GH on IGF-I and IGF-II expression in liver and muscle tissue. The results revealed a significant dose-dependent response of both hepatic IGF-I and IGF-II, and muscle IGF-I mRNA expression following rbGH administration. At the highest rbGH concentration (240μg/g BW), IGF-I mRNA levels in liver and muscle peaked significantly at 48h, indicating both hepatic and muscle IGF-I expression to be stimulated by GH. Hepatic IGF-II expression was also stimulated 48h following rbGH administration. Expression of IGF-II mRNA was not inducible in the muscle. Few studies have evaluated the effects of exogenous GH on IGF expression in ancestral vertebrate species, and as such, this research provides valuable insight into the evolution of the somatotropic axis in vertebrates.

      PubDate: 2016-06-03T02:49:32Z
  • Earthworms accumulate alanine in response to drought
    • Abstract: Publication date: September 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 199
      Author(s): Martin Holmstrup, Stine Slotsbo, Per G. Henriksen, Mark Bayley
      Earthworms have ecologically significant functions in tropical and temperate ecosystems and it is therefore important to understand how these animals survive during drought. In order to explore the physiological responses to dry conditions, we simulated a natural drought incident in a laboratory trial exposing worms in slowly drying soil for about one month, and then analyzed the whole-body contents of free amino acids (FAAs). We investigated three species forming estivation chambers when soils dry out (Aporrectodea tuberculata, Aporrectodea icterica and Aporrectodea longa) and one species that does not estivate during drought (Lumbricus rubellus). Worms subjected to drought conditions (< −2MPa) substantially increased the concentration of FAAs and in particular alanine that was significantly upregulated in all tested species. Alanine was the most important FAA reaching 250–650μmolg−1 dry weight in dehydrated Aporrectodea species and 300μmolg−1 dry weight in L. rubellus. Proline was only weakly upregulated in some species as were a few other FAAs. Species forming estivation chambers (Aporrectodea spp.) did not show a better ability to conserve body water than the non-estivating species (L. rubellus) at the same drought level. These results suggest that the accumulation of alanine is an important adaptive trait in drought tolerance of earthworms in general.

      PubDate: 2016-06-03T02:49:32Z
  • Distribution and dynamics of branchial ionocytes in houndshark reared in
           full-strength and diluted seawater environments
    • Abstract: Publication date: Available online 31 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Souichirou Takabe, Mayu Inokuchi, Yoko Yamaguchi, Susumu Hyodo
      In teleost fishes, it is well-established that the gill serves as an important ionoregulatory organ in addition to its primary function of respiratory gas exchange. In elasmobranchs, however, the ionoregulatory function of the gills is still incompletely understood. Although two types of ionocytes, Na+/K+-ATPase (NKA)-rich (type-A) cell and vacuolar-type H+-ATPase (V-ATPase)-rich (type-B) cell, have been found in elasmobranch fishes, these cells were considered to function primarily in acid–base regulation. In the present study, we examined ion-transporting proteins expressed in ionocytes of Japanese-banded houndshark, Triakis scyllium, reared in full-strength seawater (SW) and transferred to diluted (30%) SW. In addition to the upregulation of NKA and Na+/H+ exchanger type 3 (NHE3) mRNAs in the type-A ionocytes, we found that Na+, Cl− cotransporter (NCC, Slc12a3) is expressed in a subpopulation of the type-B ionocytes, and that the expression level of NCC mRNA was enhanced in houndsharks transferred to a low-salinity environment. These results suggest that elasmobranch gill ionocytes contribute to NaCl uptake in addition to the already described function of acid–base regulation, and that NCC is most probably one of the key molecules for hyper-osmoregulatory function of elasmobranch gills. The existence of two types of ionocytes (NHE3- and NCC-expressing cells) that are responsible for NaCl absorption seems to be a common feature in both teleosts and elasmobranchs for adaptation to a low salinity environment. A possible driving mechanism for NCC in type-B ionocytes is discussed.

      PubDate: 2016-04-01T23:32:05Z
  • Roles of mechanistic target of rapamycin and transforming growth
           factor-β signaling in the molting gland (Y-organ) of the blackback
           land crab, Gecarcinus lateralis
    • Abstract: Publication date: Available online 31 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ali M. Abuhagr, Kyle S. MacLea, Megan R. Mudron, Sharon A. Chang, Ernest S. Chang, Donald L. Mykles
      Molting in decapod crustaceans is controlled by molt-inhibiting hormone (MIH), an eyestalk neuropeptide that suppresses production of ecdysteroids by a pair of molting glands (Y-organs or YOs). Eyestalk ablation (ESA) activates the YOs, which hypertrophy and increase ecdysteroid secretion. At mid premolt, which occurs 7–14days post-ESA, the YO transitions to the committed state; hemolymph ecdysteroid titers increase further and the animal reaches ecdysis ~3weeks post-ESA. Two conserved signaling pathways, mechanistic target of rapamycin (mTOR) and transforming growth factor-β (TGF-β), are expressed in the Gecarcinus lateralis YO. Rapamycin, an mTOR antagonist, inhibits YO ecdysteroidogenesis in vitro. In this study, rapamycin lowered hemolymph ecdysteroid titer in ESA G. lateralis in vivo; levels were significantly lower than in control animals at all intervals (1–14days post-ESA). Injection of SB431542, an activin TGF-β receptor antagonist, lowered hemolymph ecdysteroid titers 7 and 14days post-ESA, but had no effect on ecdysteroid titers at 1 and 3days post-ESA. mRNA levels of mTOR signaling genes Gl-mTOR, Gl-Akt, and Gl-S6k were increased by 3days post-ESA; the increases in Gl-mTOR and Gl-Akt mRNA levels were blocked by SB431542. Gl-elongation factor 2 and Gl-Rheb mRNA levels were not affected by ESA, but SB431542 lowered mRNA levels at Days 3 and 7 post-ESA. The mRNA level of an activin TGF-β peptide, Gl-myostatin-like factor (Mstn), increased 5.5-fold from 0 to 3days post-ESA, followed by a 50-fold decrease from 3 to 7days post-ESA. These data suggest that (1) YO activation involves an up regulation of the mTOR signaling pathway; (2) mTOR is required for YO commitment; and (3) a Mstn-like factor mediates the transition of the YO from the activated to the committed state.

      PubDate: 2016-04-01T23:32:05Z
  • Effects of ph and bicarbonate on mitochondrial functions of marine
    • Abstract: Publication date: Available online 1 April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Fouzia Haider, Halina Falfushynska, Anna V. Ivanina, Inna M. Sokolova
      Estuarine organisms including mollusks are exposed to periodic oxygen deficiency (hypoxia) that leads to a decrease in intracellular pH and accumulation of bicarbonate (HCO3 -). These changes can affect cellular bioenergetics; however, their effects on mitochondria of estuarine mollusks are not well understood. We determined the interactive effects of bicarbonate (0-10 mM) and pH (7.2 and 6.5) on mitochondrial oxygen consumption (ṀO2), membrane potential (Δψ) and production of reactive oxygen species (ROS) in two common estuarine bivalves - hard clams Mercenaria mercenaria, and bay scallops Argopecten irradians. In both species, elevated HCO3 - levels suppressed ADP-stimulated (state 3) ṀO2 but had little effect on the resting (state 4) respiration. These effects were not mediated by the soluble adenylyl cyclase or cyclic AMP. Effects of the low pH (6.5) on mitochondrial traits were species-specific and depended on the substrate oxidized by the mitochondria. Mild acidosis (pH 6.5) had minimal effects on ṀO2 and Δψ of the bivalve mitochondria oxidizing pyruvate but led to increased rates of ROS production in clams (ROS production could not be measured in scallops). In succinate-respiring mitochondria of clams, mild acidosis suppressed ṀO2 and increased mitochondrial coupling, while in scallop mitochondria the effects of low pH were opposite. Suppression of mitochondrial oxidative phosphorylation by bicarbonate and/or acidosis may contribute to the metabolic rate depression during shell closure or environmental hypoxia/hypercapnia. These findings have implications for understanding the physiological mechanisms involved in regulation of mitochondrial bioenergetics during hypoxia exposure in estuarine bivalves.

      PubDate: 2016-04-01T23:32:05Z
  • Effects of warm acclimation on physiology and gonad development in the sea
           urchin Evechinus chloroticus
    • Abstract: Publication date: Available online 1 April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Natalí J. Delorme, Mary A. Sewell
      The physiology of the New Zealand sea urchin Evechinus chloroticus was evaluated through feeding, respiration, growth and gonad growth in adult animals acclimated for 90days at 18°C (annual mean temperature) and 24°C (ambient summer temperature (21°C) +3°C). Measured parameters with representative rates of assimilation efficiency were used to calculate scope for growth (SfG) for each treatment. All physiological parameters were negatively affected at 24°C, showing a decrease in feeding rate which coincided with negative growth and gonad development at the end of the acclimation period, and a decrease in respiration rate suggesting metabolic depression. Histology of gonad samples after the acclimation period also showed no gametic material in animals acclimated at 24°C. All animals acclimated at 24°C had negative growth, differing from the calculated SfG which indicated that the animals had sufficient energy for production. The results suggest that calculated SfG in echinoderms should be used together with actual measurements of growth in individuals as, by itself, SfG may underestimate the actual effect of ocean warming when animals are exposed to stressful conditions. Overall, considering the total loss of reproductive output observed in E. chloroticus at higher temperatures, an increase in seawater temperature could dramatically influence the persistence of northern populations of this species, leading to flow-on effects in the subtidal ecosystem.

      PubDate: 2016-04-01T23:32:05Z
  • Role of HIF-1 on phosphofructokinase and fructose 1, 6-bisphosphatase
           expression during hypoxia in the white shrimp Litopenaeus vannamei
    • Abstract: Publication date: Available online 29 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Keni Cota-Ruiz, Lilia Leyva-Carrillo, Alma B. Peregrino-Uriarte, Elisa M. Valenzuela-Soto, Teresa Gollas-Galván, Silvia Gómez-Jiménez, Jesús Hernández, Gloria Yepiz-Plascencia
      HIF-1 is a transcription factor that controls a widespread range of genes in metazoan organisms in response to hypoxia and is composed of α and β subunits. In shrimp, phosphofructokinase (PFK) and fructose bisphosphatase (FBP) are up-regulated in hypoxia. We hypothesized that HIF-1 is involved in the regulation of PFK and FBP genes in shrimp hepatopancreas under hypoxia. Long double stranded RNA (dsRNA) intramuscular injection was utilized to silence simultaneously both HIF-1 subunits, and then, we measured the relative expression of PFK and FBP, as well as their corresponding enzymatic activities in hypoxic shrimp hepatopancreas. The results indicated that HIF-1 participates in the up-regulation of PFK transcripts under short-term hypoxia since the induction caused by hypoxia (~1.6 and ~4.2-fold after 3 and 48h, respectively) is significantly reduced in the dsRNA animals treated. Moreover, PFK activity was significantly ~2.8-fold augmented after 3h in hypoxia alongside to an ~1.9-fold increment in lactate. However, when animals were dsRNA treated, both were significantly reduced. On the other hand, FBP transcripts were ~5.3-fold up-regulated in long-term hypoxic conditions (48h). HIF-1 is involved in this process since FBP transcripts were not induced by hypoxia when HIF-1 was silenced. Conversely, the FBP activity was not affected by hypoxia, which suggests its possible regulation at post-translational level. Taken together, these results position HIF-1 as a prime transcription factor in coordinating glucose metabolism through the PFK and FBP genes among others, in shrimp under low oxygen environments.

      PubDate: 2016-04-01T23:32:05Z
  • Rearing Mozambique tilapia in tidally-changing salinities: Effects on
           growth and the growth hormone/insulin-like growth factor I axis
    • Abstract: Publication date: Available online 23 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Benjamin P. Moorman, Yoko Yamaguchi, Darren T. Lerner, E. Gordon Grau, Andre P. Seale
      The growth hormone (GH)/insulin-like growth factor (IGF) axis plays a central role in the regulation of growth in teleosts and has been shown to be affected by acclimation salinity. This study was aimed at characterizing the effects of rearing tilapia, Oreochromis mossambicus, in a tidally-changing salinity on the GH/IGF axis and growth. Tilapia were raised in fresh water (FW), seawater (SW), or in a tidally-changing environment, in which salinity is switched between FW (TF) and SW (TS) every 6h, for 4months. Growth was measured over all time points recorded and fish reared in a tidally-changing environment grew significantly faster than other groups. The levels of circulating growth hormone (GH), insulin-like growth factor I (IGF-I), pituitary GH mRNA, gene expression of IGF-I, IGF-II, and growth hormone receptor 2 (GHR) in the muscle and liver were also determined. Plasma IGF-I was higher in FW and TS than in SW and TF tilapia. Pituitary GH mRNA was higher in TF and TS than in FW and SW tilapia. Gene expression of IGF-I in the liver and of GHR in both the muscle and liver changed between TF and TS fish. Fish growth was positively correlated with GH mRNA expression in the pituitary, and GHR mRNA expression in muscle and liver tissues. Our study indicates that rearing fish under tidally-changing salinities elicits a distinct pattern of endocrine regulation from that observed in fish reared in steady-state conditions, and may provide a new approach to increase tilapia growth rate and study the regulation of growth in euryhaline fish.

      PubDate: 2016-03-23T22:54:53Z
  • Temperature modulates testis steroidogenesis in European eel
    • Abstract: Publication date: Available online 21 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): David S. Peñaranda, Marina Morini, Helge Tveiten, M. Carmen Vílchez, Victor Gallego, Ron P. Dirks, Guido E.E.J.M. van den Thillart, Luz Pérez, Juan F. Asturiano
      This study evaluates the effects of temperature on hCG-induced spermatogenesis in European eel (Anguilla anguilla), subjected to three thermal regimes: T10: 10°C (first 4weeks), 15°C (next 3weeks) and 20°C (last 6weeks); T15: 15°C (first 4weeks) and 20°C (last 9weeks); and T20: constant 20°C for the duration of the experiment. At 10°C, maturation stopped in the A spermatogonial stage (SPG1), and no further maturation was observed until the temperature was ≥15°C. With the aim of explaining these results, the influence of temperature on steroidogenic enzyme gene expression and steroid synthesis was tested. The initial synthesis of androgens (T and 11-KT) increased at SPG1, and was not influenced by temperature. Likewise, the gene expression of the steroidogenic enzymes linked to androgen synthesis (aacyp11a1, aacyp17-I and aa11βHSD) also increased at SPG1. In contrast, no correlation was seen between the increase in E2 and the aacyp19a1 gene expression peak in the testes, with E2 increasing as a consequence of the seawater acclimation carried out before hormonal treatment, and peaking the aacyp19a1 gene expression at B spermatogonial stage (SPG2). Aacyp21 gene expression was also higher at SPG2, and this stage was only reached when the rearing temperature was ≥15°C. In conclusion, androgen synthesis is not dependent on temperature, but further maturation requires higher temperatures in order to induce a change in the steroidogenic pathway towards oestrogen and progestin synthesis. This study demonstrates that temperature plays a crucial role in European eel maturation, even perhaps controlling gonad development during the reproductive migration.

      PubDate: 2016-03-23T22:54:53Z
  • Daily rhythms of digestive enzyme activity and gene expression in gilthead
           seabream (Sparus aurata) during ontogeny
    • Abstract: Publication date: Available online 14 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): José Antonio Mata-Sotres, Francisco Javier Moyano, Gonzalo Martínez-Rodríguez, Manuel Yúfera
      In order to identify daily changes in digestive physiology in developing gilthead seabream larvae, the enzyme activity (trypsin, lipases and α–amylase) and gene expression (trypsinogen-try, chymotrypsinogen-ctrb, bile salt-activated lipase-cel1b, phospholipase A 2 -pla2 and α-amylase-amy2a) were measured during a 24hcycle in larvae reared under a 12h light/12h dark photoperiod. Larvae were sampled at 10, 18, 30 and 60days post hatch. In each sampling day, larvae were sampled every 3h during a complete 24hcycle. The enzyme activity and gene expression exhibited a marked dependent behavior to the light/darkness cycle in all tested ages. The patterns of activity and expression of all tested enzymes were compared to the feeding pattern found in the same larvae, which showed a rhythmic feeding pattern with a strong light synchronization. In the four tested ages, the activities of trypsin, and to a lesser extent lipases and amylase, were related to feeding activity. Molecular expression of the pancreatic enzymes tended to increase during the night, probably as an anticipation of the forthcoming ingestion of food that will take place during the next light period. It follows that the enzymatic activities are being regulated at translational and/or post-translational level. The potential variability of enzyme secretion along the whole day is an important factor to take into account in future studies. A particularly striking consequence of the present results is the reliability of studies based in only one daily sample taken at the same hour of the day, as those focused to assess ontogeny of digestive enzymes.

      PubDate: 2016-03-15T22:16:50Z
  • Assessing the reproducibility of fractional rates of protein synthesis in
           muscle tissue measured using the flooding dose technique
    • Abstract: Publication date: Available online 10 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ian D. McCarthy, James Brown
      The flooding dose technique of Garlick et al. (1980) has become the main method for measuring tissue and whole-animal rates of protein synthesis in ectotherms. However, single tissue samples are used to determine rates of protein synthesis and no studies have examined the pattern of flooding in large tissues such as the white muscle in fishes, which can comprise up to 55% of the wet body mass of a fish and which is poorly perfused. The present study has examined, for the first time, the patterns of flooding and measured rates of protein synthesis in five different regions of the white muscle in the Arctic charr Salvelinus alpinus ranging in size from 25g to 1.6kg following a flooding dose injection of L-3H-phenylalanine. The results indicate that the degree of flooding (i.e. free pool specific radioactivity relative to that of the injection solution) and elevation in free phenylalanine concentrations can vary between regions but the calculated fractional rates of protein synthesis were similar in four of the five regions studied. The variability in rates of protein synthesis increased with body size with greater variability observed between regions for fish >1kg in body mass. For consistency between studies, it is recommended that samples are taken from the epaxial muscle in the region below the dorsal fin when measuring fractional rates of white muscle synthesis in fishes.

      PubDate: 2016-03-10T21:46:31Z
  • Melatonin not only restores but also prevents the inhibition of the
           intestinal Ca2+ absorption caused by glutathione depleting drugs
    • Abstract: Publication date: Available online 9 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Vanessa Areco, Valeria Rodriguez, Ana Marchionatti, Agata Carpentieri, Nori Tolosa de Talamoni
      We have previously demonstrated that melatonin (MEL) blocks the inhibition of the intestinal Ca2+ absorption caused by menadione (MEN). The purpose of this study were to determine whether MEL not only restores but also prevents the intestinal Ca2+ absorption inhibited either by MEN or BSO, two drugs that deplete glutathione (GSH) in different ways, and to analyze the mechanisms by which MEN and MEL alter the movement of Ca2+ across the duodenum. To know this, chicks were divided into four groups: 1) controls, 2) MEN treated, 3) MEL treated, and 4) treated sequentially with MEN and MEL or with MEN and MEL at the same time. In a set of experiments, chicks treated with BSO or sequentially with BSO and MEL or with BSO and MEL at the same time were used. MEL not only restored but also prevented the inhibition of the chick intestinal Ca2+ absorption produced by either MEN or BSO. MEN altered the protein expression of molecules involved in the transcellular as well as in the paracellular pathway of the intestinal Ca2+ absorption. MEL restored partially both pathways through normalization of the O2 − levels. The nitrergic system was not altered by any treatment. In conclusion, MEL prevents or restores the inhibition of the intestinal Ca2+ absorption caused by different GSH depleting drugs. It might become one drug for the treatment of intestinal Ca2+ absorption under oxidant conditions having the advantage of low or null side effects.

      PubDate: 2016-03-10T21:46:31Z
  • Estimating the critical thermal maximum (CTmax) of bed bugs, Cimex
           lectularius: Comparing thermolimit respirometry with traditional visual
    • Abstract: Publication date: Available online 9 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Zachary C. DeVries, Stephen A. Kells, Arthur G. Appel
      Evaluating the critical thermal maximum (CT max) in insects has provided a number of challenges. Visual observations of endpoints (onset of spasms, loss of righting response, etc.) can be difficult to measure consistently, especially with smaller insects. To resolve this problem, Lighton and Turner (2004) developed a new technique: thermolimit respirometry (TLR). TLR combines real time measurements of both metabolism (V̇CO2) and activity to provide two independent, objective measures of CT max. However, several questions still remain regarding the precision of TLR and how accurate it is in relation to traditional methods. Therefore, we evaluated CT max of bed bugs using both traditional (visual) methods and TLR at three important metabolic periods following feeding (1 d, 9 d, and 21 d). Both methods provided similar estimates of CT max, although traditional methods produced consistently lower values (0.7–1°C lower than TLR). Despite similar levels of precision, TLR provided a more complete profile of thermal tolerance, describing changes in metabolism and activity leading up to the CT max, not available through traditional methods. In addition, feeding status had a significant effect on bed bug CT max, with bed bugs starved 9 d (45.19[±0.20]°C) having the greatest thermal tolerance, followed by bed bugs starved 1 d (44.64[±0.28]°C), and finally bed bugs starved 21 d (44.12[±0.28]°C). Accuracy of traditional visual methods in relation to TLR is highly dependent on the selected endpoint; however, when performed correctly, both methods provide precise, accurate, and reliable estimations of CT max .

      PubDate: 2016-03-10T21:46:31Z
  • Dopamine inhibits somatolactin Gene Expression in tilapia pituitary cells
           through the dopamine D2 receptors
    • Abstract: Publication date: Available online 10 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Quan Jiang, Anji Lian, Qi He
      Dopamine (DA) is an important neurotransmitter in the central nervous system of vertebrates and possesses key hypophysiotropic functions. Early studies have shown that DA has a potent inhibitory effect on somatolactin (SL) release in fish. However, the mechanisms responsible for DA inhibition of SL gene expression are largely unknown. To this end, tilapia DA type-1 (D1) and type-2 (D2) receptor transcripts were examined in the neurointermediate lobe (NIL) of the tilapia pituitary by real-time PCR. In tilapia, DA not only was effective in inhibiting SL mRNA levels in vivo and in vitro, but also could abolish pituitary adenylate cyclase-activating polypeptide (PACAP)- and salmon gonadotropin-releasing hormone (sGnRH)-stimulated SL gene expression at the pituitary level. In parallel studies, the specific D2 receptor agonists quinpirole and bromocryptine could mimic the DA-inhibited SL gene expression. Furthermore, the D2 receptor antagonists domperidone and (−)-sulpiride could abolish the SL response to DA or the D2 agonist quinpirole, whereas D1 receptor antagonists SCH23390 and SKF83566 were not effective in this respect. In primary cultures of tilapia NIL cells, D2 agonist quinpirole-inhibited cAMP production could be blocked by co-treatment with the D2 antagonist domperidone and the ability of forskolin to increase cAMP production was also inhibited by quinpirole. Using a pharmacological approach, the AC/cAMP pathway was shown to be involved in quinpirole-inhibited SL mRNA expression. These results provide evidence that DA can directly inhibit SL gene expression at the tilapia pituitary level via D2 receptor through the AC/cAMP-dependent mechanism.

      PubDate: 2016-03-10T21:46:31Z
  • Identification of a heat shock protein 90 gene involved in resistance to
           temperature stress in two wing-morphs of Nilaparvata lugens (Stål)
    • Abstract: Publication date: Available online 3 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kai Lu, Xia Chen, Wenting Liu, Qiang Zhou
      The brown planthopper, Nilaparvata lugens, is one of the most destructive pests damaging rice in Asia and exhibits wing dimorphism, with brachypters possessing severely reduced wings and macropters bearing fully developed wings. Previous studies have shown that macropters are more heat resistant than brachypters. To understand the molecular mechanism underlying the differential thermotolerance abilities of these two morphs, a full-length Hsp gene, NlHsp90 was cloned from N. lugen. Our results showed that the relative expression levels of NlHsp90 in N. lugens females increased with the rise of temperature. Interestingly, NlHsp90 in macropters females could be induced at lower temperature (32°C) than that in brachypters (34°C), and the NlHsp90 mRNA levels in macropters were significantly higher than those in brachypters from 34 to 40°C. In addition, the maximum expression levels of NlHsp90 were achieved much earlier in macropters, and NlHsp90 mRNA levels in macropters were significantly higher than those in brachypters from 1 to 6h of recovery after temperature stress. Furthermore, knockdown of NlHsp90 by dsRNA injection reduced survival in both morphs with a greater reduction in the macropters relative to that of the brachyters. These results indicated that NlHsp90 plays an important role for thermotolerance in N. lugens, and there is difference on induction between two morphs.

      PubDate: 2016-03-05T21:40:46Z
  • Thermal acclimation to cold alters myosin content and contractile
           properties of rainbow smelt, Osmerus mordax, red muscle
    • Abstract: Publication date: Available online 3 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): David J. Coughlin, Lisa P. Shiels, Seshuvardhan Nuthakki, Jacie L. Shuman
      Rainbow smelt (Osmerus mordax), a eurythermal fish, live in environments from −1.8 to 20°C, with some populations facing substantial annual variation in environmental temperature. These different temperature regimes pose distinct challenges to locomotion by smelt. Steady swimming performance, red muscle function and muscle myosin content were examined to assess the prediction that cold acclimation by smelt will lead to improved steady swimming performance and that any performance shift will be associated with changes in red muscle function and in its myosin heavy chain composition. Cold acclimated (4°C) smelt had a faster maximum steady swimming speed and swam with a higher tailbeat frequency than warm acclimated (10°C) smelt when tested at the same temperature (10°C). Muscle mechanics experiments demonstrated faster contractile properties in the cold acclimated fish when tested at 10°C. The red muscle of cold acclimated smelt had a shorter twitch times, a shorter relaxation times and a higher maximum shortening velocity. In addition, red muscle from cold acclimated fish displayed reduced thermal sensitivity to cold, maintaining higher force levels at 4°C compared to red muscle from warm acclimated fish. Immunohistochemistry suggests shifts in muscle myosin composition and a decrease in muscle cross-sectional area with cold acclimation. Dot blot analysis confirmed a shift in myosin content. Rainbow smelt do show a significant thermal acclimation response to cold. An examination of published values of maximum muscle shortening velocity in fishes suggests that smelt are particularly well suited to high levels of activity in very cold water.

      PubDate: 2016-03-05T21:40:46Z
  • Thermal impacts on the growth, development and ontogeny of critical
           swimming speed in Atlantic herring larvae
    • Abstract: Publication date: Available online 3 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marta Moyano, Björn Illing, Philip Peschutter, Klaus B. Huebert, Myron A. Peck
      Increases in swimming ability have a profound influence on larval fish growth and survival by increasing foraging success, predator avoidance and the ability to favorably influence transport. Understanding how development and environmental factors combine to influence swimming performance in aquatic organisms is particularly important during the transition from viscous to inertial environments. We measured the growth, development and ontogenetic changes in critical swimming speed (U crit ) in Atlantic herring (Clupea harengus) larvae reared at three temperatures (7, 11, 15°C). Temperature had a significant effect on growth rates (from 0.21 at 7°C to 0.34mm·d−1 at 15°C), and larval morphology-at-length (increased dry weight (DW), body height and developmental rate at warmer temperatures). Temperature-dependent differences in morphology influenced swimming performance (e.g. the exponential increase in U crit with increasing body size was faster at warmer temperatures). Larvae entered the transition to an inertial environment (Reynolds numbers ≥300) at body lengths between 15 (15°C) and 17mm (7°C). Inter-individual differences in U crit were not related to nutritional condition (RNA·DNA −1 or DNA·DW −1), but were negatively correlated to length-at-age, suggesting a trade-off between growth rate and locomotor activity. The U crit data from this and previously published studies suggest that Atlantic herring pass through four activity phases: 1) yolk-sac (<0.6cm·s−1), 2) pre-flexion (0.6–3.0cm·s−1, temperature effect changes with body size), 3) post-flexion (up to 6–8cm·s−1, Q 10 ~1.8–2.0), 4) juvenile–adult period (20–170cm·s−1).

      PubDate: 2016-03-05T21:40:46Z
  • Seawater acidification affects the physiological energetics and spawning
           capacity of the Manila clam Ruditapes philippinarum during gonadal
    • Abstract: Publication date: Available online 26 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Xian Xu, Feng Yang, Liqiang Zhao, Xiwu Yan
      Ocean acidification is predicted to have widespread implications for marine bivalve mollusks. While our understanding of its impact on their physiological and behavioral responses is increasing, little is known about their reproductive responses under future scenarios of anthropogenic climate change. In this study, we examined the physiological energetics of the Manila clam Ruditapes philippinarum exposed to CO2-induced seawater acidification during gonadal maturation. Three recirculating systems filled with 600 L of seawater were manipulated to three pH levels (8.0, 7.7, and 7.4) corresponding to control and projected pH levels for 2100 and 2300. In each system, temperature was gradually increased ca. 0.3°C per day from 10 to 20°C for 30days and maintained at 20°C for the following 40days. Irrespective of seawater pH levels, clearance rate (CR), respiration rate (RR), ammonia excretion rate (ER), and scope for growth (SFG) increased after a 30-day stepwise warming protocol. When seawater pH was reduced, CR, ratio of oxygen to nitrogen, and SFG significantly decreased concurrently, whereas ammonia ER increased. RR was virtually unaffected under acidified conditions. Neither temperature nor acidification showed a significant effect on food absorption efficiency. Our findings indicate that energy is allocated away from reproduction under reduced seawater pH, potentially resulting in an impaired or suppressed reproductive function. This interpretation is based on the fact that spawning was induced in only 56% of the clams grown at pH 7.4. Seawater acidification can therefore potentially impair the physiological energetics and spawning capacity of R. philippinarum.

      PubDate: 2016-02-29T21:17:16Z
  • Endocrine consequences of an acute stress under different thermal
           conditions: A study of corticosterone, prolactin, and thyroid hormones in
           the pigeon (Columbia livia)
    • Abstract: Publication date: Available online 24 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Frédéric Angelier, Charline Parenteau, Stéphanie Ruault, Nicole Angelier
      In the context of global change, the physiological and hormonal stress responses have received much attention because of their implications in terms of allostasis. However, most studies have focused on glucocorticoids only as the “common” response to stressors while neglecting other endocrine axes and hormones (e.g. prolactin, thyroid hormones) that play a crucial role in metabolic adjustments. Interestingly, the responsiveness of all these endocrine axes to stress may depend on the energetic context and this context-dependent stress response has been overlooked so far. In the wild, temperature can vary to a large extent within a short time window and ambient temperature may affect these metabolic-related endocrine axes, and potentially, their responsiveness to an acute stressor. Here, we explicitly tested this hypothesis by examining the effect of a standardized stress protocol on multiple hormonal responses in the rock pigeon (Columbia livia). We tested the effect of an acute restraint stress on (1) corticosterone levels, (2) prolactin levels, and (3) thyroid hormone levels (triiodothyronine, thyroxine) in pigeons that were held either at cool temperature (experimental birds) or at room temperature (control birds) during the stress protocol. Although we found a significant influence of restraint stress on most hormone levels (corticosterone, prolactin, and thyroxine), triiodothyronine levels were not affected by the restraint stress. This demonstrates that stressors can have significant impact on multiple endocrine mechanisms. Importantly, all of these hormonal responses to stress were not affected by temperature, demonstrating that the exposure to cold temperature does not affect the way these hormone levels change in response to handling stress. This suggests that some endocrine responses to temperature decreases may be overridden by the endocrine responses to an acute restraint stress.

      PubDate: 2016-02-24T20:44:35Z
  • Regional variation of gene regulation associated with storage lipid
           metabolism in American glass eels (Anguilla rostrata)
    • Abstract: Publication date: Available online 24 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mélanie Gaillard, Scott A. Pavey, Caroline L. Côté, Réjean Tremblay, Louis Bernatchez, Céline Audet
      Variation in gene regulation may be involved in the differences observed for life history traits within species. American eel (Anguilla rostrata ) is well known to harbour distinct ecotypes within a single panmictic population. We examined the expression of genes involved in the regulation of appetite as well as lipid and glycogen among glass eels migrating to different locations on the Canadian east coast and captured at two different periods of upstream migration. Gene expression levels of three reference and five candidate genes were analyzed by real-time PCR with Taqman probes in recently captured wild glass eels. All gene transcripts were detected in glass eels. Of the five candidate genes, bile salt activated and triacylglycerol lipases were respectively 7.65 and 3.25 times more expressed in glass eels from the St. Lawrence estuary than in those from Nova Scotia, and there was no effect related to the two-week difference in capture date. These two genes explained 82.41% of the dissimilarity between the two rivers. In contrast, glycogen phosphorylase, ghrelin, and leptin receptor genes showed no significant differences in gene transcription. These results confirmed at the molecular level an observation that was recently made at the phenotypic level: that glass eels from the St. Lawrence estuary have a greater capacity to use lipid reserves to sustain their metabolic needs. These observations add to the body of evidence supporting the hypothesis that regional phenotypic variation observed in American eel is determined early in life and that part of this variation is likely under genetic control. Keywords ecotypes, ghrelin, glycogen phosphorylase, leptin receptor, lipase, mRNA expression, transcriptomics

      PubDate: 2016-02-24T20:44:35Z
  • Gonadotropin and sf-1 regulation of cyp19a1a gene and aromatase activity
           during oocyte development in the rohu, L. rohita
    • Abstract: Publication date: Available online 23 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sujata Roy Moulik, Puja Pal, Suravi Majumder, Buddhadev Mallick, Shreyasi Gupta, Payel Guha, Sibsankar Roy, Dilip Mukherjee
      Cytochrome P450 aromatase (P450arom), a product of cyp19a1 gene, plays pivotal roles in vertebrate steroidogenesis and reproduction. In this study, we isolated partial cDNA encoding the ovarian (cyp19a1a) and brain (cyp19a1b) P450arom genes from adult female rohu, Labeo rohita and investigated the regulation of cyp19a1a by gonadotropin and SF-1. The cyp19a1a and cyp19a1b were expressed predominantly in the ovary and brain respectively, with quantity of the former attuned to reproductive cycle. To elucidate gonadotropin regulation of cyp19a1a mRNA expression and P450 aromatase activity for 17β-estradiol (E2) biosynthesis in vitro by the vitellogenic ovarian follicles, time- and dose-dependent studies were conducted with HCG and porcine FSH. Results demonstrated that HCG stimulated significantly higher expression of cyp19a1a mRNA and aromatase activity leading to increased biosynthesis of E2 than FSH. To understand the involvement of SF-1 to in the regulation of cyp19a1a and aromatase activity, ovarian follicles were incubated with increasing concentrations of HCG and expression of sf1gene and activation of SF-1 protein were measured. Results demonstrated that HCG significantly induced expression of sf1gene and activation of SF-1 protein suggesting a link between SF-1 and P450 aromatase activation in this fish ovary during gonadotropin-induced steroidogenesis.

      PubDate: 2016-02-24T20:44:35Z
  • Local adaptation to osmotic environment in killifish, Fundulus
           heteroclitus, is supported by divergence in swimming performance but not
           by differences in excess post-exercise oxygen consumption or aerobic scope
    • Abstract: Publication date: Available online 12 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Reid S. Brennan, Ruth Hwang, Michelle Tse, Nann Fangue, Andrew Whitehead
      Regulation of internal ion homeostasis is essential for fishes inhabiting environments where salinities differ from their internal concentrations. It is hypothesized that selection will act to reduce energetic costs of osmoregulation in a population's native osmotic habitat, producing patterns of local adaptation. Killifish, Fundulus heteroclitus, occupy estuarine habitats where salinities range from fresh water to seawater. Populations inhabiting an environmental salinity gradient differ in physiological traits associated with acclimation to acute salinity stress, consistent with local adaptation. Similarly, metabolic rates differ in populations adapted to different temperatures, but have not been studied in regard to salinity. We investigated evidence for local adaptation between populations of killifish native to fresh and brackish water habitats. Aerobic scope (the difference between minimum and maximum metabolic rates), excess post-exercise oxygen consumption, and swimming performance (time and distance to reach exhaustion) were used as proxies for fitness in fresh and brackish water treatments. Swimming performance results supported local adaptation; fish native to brackish water habitats performed significantly better than fresh water-native fish at high salinity while low salinity performance was similar between populations. However, results from metabolic measures did not support this conclusion; both populations showed an increase in resting metabolic rate and a decrease of aerobic scope in fresh water. Similarly, excess post-exercise oxygen consumption was higher for both populations in fresh than in brackish water. While swimming results suggest that environmentally dependent performance differences may be a result of selection in divergent osmotic environments, the differences between populations are not coupled with divergence in metabolic performance.

      PubDate: 2016-02-16T20:17:55Z
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