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BIOCHEMISTRY (205 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Chemical Biology     Full-text available via subscription   (Followers: 308)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 9)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 6)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 7)
Advances in Biological Chemistry     Open Access   (Followers: 5)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 6)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
African Journal of Biochemistry Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 6)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 180)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Polymer Science     Open Access   (Followers: 17)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 205)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 28)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 17)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 7)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 9)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access  
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 3)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 15)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 3)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
Biochemical Genetics     Hybrid Journal   (Followers: 2)
Biochemical Journal     Full-text available via subscription   (Followers: 16)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 3)
Biochemistry     Full-text available via subscription   (Followers: 222)
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 9)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 18)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 6)
Biochimie     Hybrid Journal   (Followers: 4)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 14)
BioDrugs     Full-text available via subscription   (Followers: 7)
Bioelectrochemistry     Hybrid Journal   (Followers: 3)
Biofuels     Hybrid Journal   (Followers: 7)
Biogeochemistry     Hybrid Journal   (Followers: 7)
BioInorganic Reaction Mechanisms     Full-text available via subscription   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 11)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 6)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 17)
BMC Biochemistry     Open Access   (Followers: 8)
BMC Chemical Biology     Open Access   (Followers: 4)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 3)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 5)
ChemBioChem     Hybrid Journal   (Followers: 2)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Journal     Hybrid Journal   (Followers: 20)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Full-text available via subscription   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 2)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 16)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 3)
Clinical Chemistry and Laboratory Medicine     Full-text available via subscription   (Followers: 5)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 3)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Current Chemical Biology     Hybrid Journal   (Followers: 2)

        1 2 3     

Journal Cover Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
   [7 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1095-6433
     Published by Elsevier Homepage  [2573 journals]
  • Neuropeptide Y promotes adipogenesis in chicken adipose cells in vitro
    • Abstract: Publication date: Available online 22 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Wei Zhang , Shiping Bai , Dongmin Liu , Mark Andrew Cline , Elizabeth Ruth Gilbert
      Neuropeptide Y is an evolutionarily conserved neurotransmitter that stimulates food intake in higher vertebrate species and promotes adipogenesis in mammals. The objective of this study was to determine if NPY also enhances adipogenesis in birds, using chickens as a model. The stromal-vascular fraction of cells was isolated from the abdominal fat of 14day-old broiler chicks and effects of exogenous chicken NPY on proliferation and differentiation determined. Based on a thymidine analog incorporation assay and gene expression analysis, there was no effect of NPY on proliferation during the first 12hours post-treatment in cells that were induced to proliferate. However, there were effects of NPY treatment on proliferation and lipid accumulation during the first 6days post-induction of differentiation. Neuropeptide Y supplementation during induction of differentiation was associated with greater glycerol-3-phosphate dehydrogenase activity and staining for neutral lipids, indicative of augmented lipid accumulation. This was also accompanied by increased proliferation during differentiation, which was characterized by up-regulation of proliferation and preadipocyte marker mRNA, and a greater number of proliferating cells in groups that were treated with NPY. Additionally, NPY treatment was associated with increased expression of fatty acid binding protein 4 and lipoprotein lipase during differentiation. In conclusion, these results suggest that NPY plays a role in promoting adipogenesis in chickens and that the mechanisms involve an increase in the synthesis of new preadipocytes and increased lipid synthesis and storage.

      PubDate: 2014-11-24T00:05:12Z
  • GnRH mRNA levels in male three-spined sticklebacks, Gasterosteus
           aculeatus, under different reproductive conditions
    • Abstract: Publication date: February 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 180
      Author(s): Yi Ta Shao , Yung Che Tseng , Chia-Hao Chang , Hong Young Yan , Pung Pung Hwang , Bertil Borg
      In vertebrates, reproduction is regulated by the brain–pituitary–gonad (BPG) axis, where the gonadotropin-releasing hormone (GnRH) is one of the key components. However, very little is known about the possible role of GnRH in the environmental and feedback control of fish reproduction. To investigate this, full-length gnrh2 (chicken GnRH II) and gnrh3 (salmon GnRH) sequences of male three-spined sticklebacks (Gasterosteus aculeatus), which are clustered with the taxa of the same GnRH type as other Euteleostei, were cloned and annotated. gnrh1 is absent in this species. The mRNA levels of gnrh2 and gnrh3 in the sticklebacks' brain were measured under breeding and post-breeding conditions as well as in castrated and sham-operated breeding fish and castrated/sham-operated fish kept under long-day (LD 16:8) and short-day (LD 8:16) conditions. Fully breeding males had considerably higher mRNA levels of gnrh2 and gnrh3 in the thalamus (Th) and in the telencephalon and preoptic area (T+POA), respectively, than post-breeding males. Sham-operated breeding males have higher gnrh3 mRNA levels than the corresponding castrated males. Moreover, higher gnrh2 mRNA levels in the Th and higher gnrh3 mRNA levels in the T+POA and hypothalamus (HypTh) were also found in long-day sham-operated males than in sham-operated fish kept under an inhibitory short day photoperiod. Nevertheless, gnrh2 and gnrh3 mRNA levels were not up-regulated in castrated males kept under long-day photoperiod, which suggests that positive feedbacks on the brain-pituitary-gonad axis are necessary for this response.

      PubDate: 2014-11-24T00:05:12Z
  • Methane emission by adult ostriches (Struthio camelus)
    • Abstract: Publication date: February 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 180
      Author(s): Samuel Frei , Marie T. Dittmann , Christoph Reutlinger , Sylvia Ortmann , Jean-Michel Hatt , Michael Kreuzer , Marcus Clauss
      Ostriches (Struthio camelus) are herbivorous birds with a digestive physiology that shares several similarities with that of herbivorous mammals. Previous reports, however, claimed a very low methane emission from ostriches, which would be clearly different from mammals. If this could be confirmed, ostrich meat would represent a very attractive alternative to ruminant—and generally mammalian—meat by representing a particularly low-emission agricultural form of production. We individually measured, by chamber respirometry, the amount of oxygen consumed as well as carbon dioxide and methane emitted from six adult ostriches (body mass 108.3±8.3kg) during a 24-hour period when fed a pelleted lucerne diet. While oxygen consumption was in the range of values previously reported for ostriches, supporting the validity of our experimental setup, methane production was, at 17.5±3.2Ld−1, much higher than previously reported for this species, and was of the magnitude expected for similar-sized, nonruminant mammalian herbivores. These results suggest that methane emission is similar between ostriches and nonruminant mammalian herbivores and that the environmental burden of these animals is comparable. The findings furthermore indicate that it appears justified to use currently available scaling equations for methane production of nonruminant mammals in paleo-reconstructions of methane production of herbivorous dinosaurs.

      PubDate: 2014-11-19T23:49:50Z
  • Expression of stress-related genes in the parthenogenetic forms of the pea
           aphid, Acyrthosiphon pisum
    • Abstract: Publication date: Available online 15 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Pavel Jedlička , Veronika Jedličková , How-Jing Lee
      Aphids are an economically important group of insects that have an intricate life cycle with seasonal polyphenism. This study aimed to explore the physiological background of aphid migration from unfavorable nutritional conditions to a new, intact host plant. Specifically, the relative expression of stress/metabolism-related genes and changes in metabolic reserves were determined for the winged and wingless forms of female pea aphids, Acyrthosiphon pisum, under two different nutritional conditions. The expression level was determined for the following sets of genes: the adipokinetic hormone (AKH) and its receptor, enzymes involved in carbohydrate and lipid metabolism, detoxifying enzymes, and genes encoding exoskeleton/cuticular proteins and cytoskeleton proteins. In both forms, the transcription of the adipokinetic hormone was upregulated during nutritional stress, whereas its receptor mRNA levels remained unchanged. Similarly, the expression of genes engaged in glycogen and triglyceride degradation was elevated. Glycogen reserves and phospholipids appeared to be used during stress. In comparison, nutrient rich reproductively active females of both forms appeared to use triglycerides. Moreover, we revealed changes in the mRNA level of the detoxifying genes delta-class glutathione S-transferase (GST-δ) and cytochrome P450 monooxygenase (CYP450), as well as the CP gene (which encodes exoskeleton/cuticular proteins) and the cofilin gene (the products of which influence cytoskeleton organization). These results indicate the possible correlation between nutritional stress, energy content, AKH, and the stress-related enzymes of different metabolic pathways in winged and wingless forms of A.pisum.

      PubDate: 2014-11-15T23:36:53Z
  • Development and characterization of an endothelial cell line from the
           bulbus arteriosus of walleye, Sander vitreus
    • Abstract: Publication date: Available online 15 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Nguyen T.K. Vo , Ci Chen , Lucy E.J. Lee , John S. Lumsden , Brian Dixon , Niels C. Bols
      A cell line has been developed from the bulbus arteriosus (BA) of the walleye (WE), Sander vitreus (Mitchill), and is termed WEBA. WEBA produced collagen I, and when held at confluency for days or weeks, spontaneously formed capillary-like tubes. WEBA cells bound fluorescently-labeled Ulex europaeus lectin agglutinin I (UEA-1), took up acetylated low density lipoprotein (Ac-LDL), stained for von Willebrand factor (vWF), and produced nitric oxide (NO). The cytoskeleton consisted at least of α- and β- tubulin, vimentin, and actin, with the actin organized into circumferential bundles. Immunofluorescence staining revealed at least two tight junction proteins, zonula occludens -1 (ZO-1) and claudin 3. Together these results suggest that WEBA is an endothelial cell line. Relatively high doses of 2,3,7,8-tetrachlorodibenzodioxin (TCDD) induced cytochrome P4501A (CYP1A) protein and 7-ethoxyresorufin o-deethylase (EROD) activity in WEBA. As one of the first fish endothelial and BA cell lines, WEBA should be useful in many disciplines in which the teleost cardiovascular system is a focus.

      PubDate: 2014-11-15T23:36:53Z
  • High consumption of fructose rather than glucose promotes a diet-induced
           obese phenotype in Drosophila melanogaster
    • Abstract: Publication date: Available online 15 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Bohdana M. Rovenko , Natalia V. Perkhulyn , Dmytro V. Gospodaryov , Alberto Sanz , Oleh V. Lushchak , Volodymyr I. Lushchak
      During the last twenty years, there has been a considerable scientific debate about the possible mechanisms of induction of metabolic disorders by reducing monosaccharides such as glucose or fructose. In this study, we report the metabolic rearrangement in response to consumption of these monosaccharides at concentrations ranging from 0.25 to 20% in a Drosophila model. Flies raised on high-glucose diet displayed delay in pupation and increased developmental mortality compared with fructose consumers. Both monosaccharides at high concentrations promoted an obese-like phenotype indicated by increased fly body mass, levels of uric acid, and circulating and stored carbohydrates and lipids; and decreased percentage of water in the body. However, flies raised on fructose showed lower levels of circulating glucose and higher concentrations of stored carbohydrates, lipids, and uric acid. The preferential induction of obesity caused by fructose in Drosophila was associated with increased food consumption and reduced mRNA levels of DILP2 and DILP5 in the brain of adult flies. Our data show that glucose and fructose differently affect carbohydrate and lipid metabolism in Drosophila in part by modulation of insulin/insulin-like growth factor signaling. Some reported similarities with effects observed in mammals make Drosophila as a useful model to study carbohydrate influence on metabolism and development of metabolic disorders.

      PubDate: 2014-11-15T23:36:53Z
  • Cold acclimation allows regulation of chloride secretion in a eurythermic
           teleost fish Fundulus heteroclitus
    • Abstract: Publication date: Available online 15 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Alicia M. Malone , Regina R.F. Cozzi , William S. Marshall
      Fundulus heteroclitus (mummichog or common killifish) is an ideal model for ion transport regulation in chloride cells of the opercular epithelium (OE) and the response to thermal challenge. Mummichogs were acclimated to warm (20 °C) and cold (5 °C) seawater and opercular epithelia dissected and mounted in isolated Ussing-style epithelia chambers. The α2 adrenergic agonist clonidine inhibited the Cl- secretion (measured as short-circuit current, Isc ), while the β-adrenergic agonist isoproterenol and 1.0 mM dibutyryl cyclic adenosine monophosphate (db-cAMP) plus 0.1 mM isobutyl methylxanthine (IBMX) stimulated I sc in OE from warm and cold acclimated fish, measured at 20 oC. In contrast, rapid cooling partially inhibited Isc , but totally blocked the inhibition by clonidine and stimulation by isoproterenol and db-cAMP+IBMX in OE from warm-acclimated fish, while OE from cold-acclimated animals responded normally at 5 oC. Warming epithelia from 5 oC to 20 oC restored Isc and stimulation by db-cAMP+IBMX markedly increased Isc to levels similar to warm acclimated epithelia, while isoproterenol was much less effective. The isoproterenol insensitivity suggests a downregulation of β-adrenergic receptors in the cold. We infer from present results and previous work (Buhariwalla et al. 2012) that cold shock of plasma membranes induces a phase shift from liquid to gel state that impaired plasma membrane protein mobility of necessary hormone regulatory functions, while cold acclimation preserved ion transport regulation via homeoviscous adaptation of plasma membrane lipids.

      PubDate: 2014-11-15T23:36:53Z
  • Rapid desiccation hardening changes the cuticular hydrocarbon profile of
           Drosophila melanogaster
    • Abstract: Publication date: Available online 9 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Joseph R. Stinziano , Richard J. Sové , Howard D. Rundle , Brent J. Sinclair
      The success of insects in terrestrial environments is due in large part to their ability to resist desiccation stress. Since the majority of water is lost across the cuticle, a relatively water-impermeable cuticle is a major component of insect desiccation resistance. Cuticular permeability is affected by the properties and mixing effects of component hydrocarbons, and changes in cuticular hydrocarbons can affect desiccation tolerance. A pre-exposure to a mild desiccation stress increases duration of desiccation survival in adult female Drosophila melanogaster, via a decrease in cuticular permeability. To test whether this acute response to desiccation stress is due to a change in cuticular hydrocarbons, we treated male and female D. melanogaster to a rapid desiccation hardening (RDH) treatment and used gas chromatography to examine the effects on cuticular hydrocarbon composition. RDH led to reduced proportions of unsaturated and methylated hydrocarbons compared to controls in females, but although RDH modified the cuticular hydrocarbon profile in males, there was no coordinated pattern. These data suggest that the phenomenon of RDH leading to reduced cuticular water loss occurs via an acute change in cuticular hydrocarbons that enhances desiccation tolerance in female, but not male, D. melanogaster.

      PubDate: 2014-11-11T23:10:26Z
  • Exogenous recombinant bovine growth hormone stimulates growth and hepatic
           IGF expression in shovelnose sturgeon Scaphirhynchus platorhynchus
    • Abstract: Publication date: Available online 8 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Carlin M. Fenn , Brian C. Small
      Sturgeon are a unique fish for physiological research, as they are long lived, slow growing, and late maturing. Furthermore, sturgeon growth hormones appear to share greater structural and molecular similarity with mammalian somatotropins than teleostean somatotropins. In this study, changes in insulin-like growth factor (IGF)-I and –II mRNA expression and corresponding whole body growth and composition following 6weeks of bi-weekly recombinant bovine growth hormone (rbGH) administration in shovelnose sturgeon Scaphirhynchus platorhynchus were evaluated. Fish were injected intraperitoneally with 240μg rbGH/g body weight or a sesame oil sham. Hepatic IGF-I and –II mRNA abundance was significantly higher (P≤0.02) in rbGH treated fish, as were length (P<0.001) and weight gain (P<0.001). In addition, proximate whole-body analysis demonstrated a significant (P<0.05) increase in protein composition of rbGH treated fish versus sham treated fish. There were no significant differences in whole-body moisture, lipid, or ash between the two treatments. These results demonstrate functional roles for GH and IGFs in the promotion of lean growth within this ancient fish species, and support the view that the functional effects of GH on hepatic IGF-I expression and somatic growth are conserved from chondostrean to teleostean fishes.

      PubDate: 2014-11-11T23:10:26Z
  • Two general-odorant binding proteins in Spodoptera litura are
           differentially tuned to sex pheromones and plant odorants
    • Abstract: Publication date: Available online 10 November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Nai-Yong Liu , Ke Yang , Yan Liu , Wei Xu , Alisha Anderson , Shuang-Lin Dong
      Moths have evolved a sensitive and sophisticated olfactory system to sense a variety of semiochemicals from the external environment. In chemosensory processes, the odorant binding protein (OBP) is an essential element for filtering, binding and transporting hydrophobic odorant molecules to the specific receptors. Here focusing on a major sub-class of lepidopteran OBPs, general-odorant binding proteins (GOBPs), we explored the relationship and functional difference between two GOBP members from a noctuid species Spodoptera litura. Using genomic DNA as the template, we demonstrated that SlitGOBP2 and three SlitPBPs are clustered on the same chromosome within a close proximity. qPCR results showed that two SlitGOBPs were primarily expressed in antennae at similar levels between females and males, but GOBP2 displayed much higher expression than GOBP1. Binding studies revealed that both SlitGOBP1 and 2 strongly bound C14-C16 alcohol-pheromone analogs with high affinities (Ki <1.0μM). However, SlitGOBP2 also strongly bound most acetate- and aldehyde-sex pheromone components and analogs, while SlitGOBP1 could not. For tested plant odorants, SlitGOBP1 showed a relatively broad ligand-binding spectrum with moderate affinities, while SlitGOBP2 was tuned to some compounds with strong binding activities (Ki <5.0μM). Finally, by molecular docking we explored the differences in protein structures and potential key residues in the binding pockets between the two SlitGOBPs. Taken together, our study strongly suggests that SlitGOBP2 and SlitPBPs evolved by gene duplication events, and two SlitGOBPs have functionally differentiated in odorant recognition.

      PubDate: 2014-11-11T23:10:26Z
  • Immune response, oxidative stress and dietary antioxidants in great tit
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Viviana Marri , Heinz Richner
      The activation of immune defences counteracts pathogens, but mounting an immune response is costly and can negatively impact life-history traits. Immune activation releases highly reactive species that kill pathogens but can also cause oxidative damage to host tissues, and these negative effects may therefore constrain further investment in immune responses. To offset these toxic effects, animals rely on a complex system of antioxidants. Here, we tested if vitamin E, a dietary antioxidant, can reduce oxidative damage induced by an immune challenge and thus enhance the immune response. In a 2×2 experimental design, we supplemented great tit nestlings with either vitamin E or a placebo, and then injected them with either a bacterial lipopolysaccharide (LPS), or a buffer solution (PBS) as a control. LPS-treated nestlings mounted an inflammatory response and increased antioxidant capacity, without any change in ROM (reactive oxygen metabolites), an index of early oxidative damage. These results suggest that the likely transient increase in reactive species of the LPS injection was counteracted by a rise in endogenous antioxidant defences that was independent of supplementary dietary antioxidants. Indeed, vitamin E supplementation neither affected oxidative status nor enhanced the immune response, suggesting that in our experimental condition great tit nestlings were not limited in vitamin E and in antioxidants in general. Overall, our results show that birds can mount an effective antioxidant response to face an immune challenge, and can therefore avoid stress caused by a transient increase in reactive species generated by immune activation.

      PubDate: 2014-11-11T23:10:26Z
  • Carbon dioxide sensitivity and its role in multifunctional neurons in the
           mollusk Onchidium
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Takako Nishi
      Intrinsically photoresponsive neurons in the abdominal ganglion of the amphibious mollusk Onchidium named Ip-1 and Ip-2 (Ip-1/2) react to several different stimuli. These neurons respond to light with slow hyperpolarization and to CO2 stimulation with slow depolarization. In this study, increasing the concentration of CO2 in the air caused hyperventilation and enlargement of the pneumostome in the intact animal. In a semi-intact preparation, pouring artificial seawater (ASW) with dissolved CO2 onto the central ganglia caused the previously closed pneumostome to open. In an ASW environment, Ip-1/2 neurons depolarized even under conditions of constant pH (alkaline ASW) and after dissolution of CO2. This depolarization prolonged the firing of action potentials in Ip-1/2 neurons. Adding protons (H+) to ASW caused Ip-1/2 depolarization only when the neurons' membranes were depolarized to a potential above the resting potential. Furthermore, in the presence of the carbonic anhydrase inhibitor acetazolamide (AZ), CO2-induced excitation in Ip-1/2 neurons was increased in both normal and alkaline ASW. These results suggest that when dissolved in ASW, CO2 directly induced the depolarizing response in Ip-1/2 neurons. Since Ip-1/2 neurons participate in pneumostome opening, these results suggest that increased CO2 levels in ASW directly stimulate CO2-sensitive central neurons, promoting ventilation.

      PubDate: 2014-11-07T22:35:25Z
  • Faecal particle size: Digestive physiology meets herbivore diversity
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Marcus Clauss , Patrick Steuer , Kerstin Erlinghagen-Lückerath , Jacques Kaandorp , Julia Fritz , Karl-Heinz Südekum , Jürgen Hummel
      In herbivore ecophysiology, comparative chewing efficiency has only recently received increased attention. This measure is best assessed on un-processed forage-only diets; corresponding comparative datasets are missing. We measured a faecal mean particle size (MPS [mm]) in 14 large herbivore species (body mass (M) range 60–4000kg; 8 ruminants and 6 hindgut fermenters) fed a consistent grass hay diet, in which intake, digesta mean retention times (MRT [h]) and digestive efficiency (as digestibility of faecal fibre measured by 96h cumulative in vitro gas production GP96h [ml per 200mg faecal fibre], and metabolic faecal nitrogen MFN [% organic faecal matter]) had been quantified simultaneously. MPS was generally lower in ruminants than in hindgut fermenters and increased with M in the total dataset, but was nearly constant among closely related taxa (e.g. within ruminants, within equids) irrespective of M. MPS (but not MRT) was significantly correlated to GP96h, whereas MRT (but not MPS) was significantly correlated to MFN, suggesting different effects of these factors on different aspects of digestibility. Combinations of measures including MPS mostly explained digestibility better than other combinations. The phylogenetic signal λ, which was mostly 1 when linking any single measure to digestibility, was estimated 0 in models that linked digestive efficiency to combinations of measures. These results support the intuitive concept that species diversification in large herbivores is tightly related to digestive physiology, and that chewing efficiency as measured by faecal particle size is an integral aspect of this scenario.

      PubDate: 2014-11-07T22:35:25Z
  • The combined effect of hypoxia and nutritional status on metabolic and
           ionoregulatory responses of common carp (Cyprinus carpio)
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Sofie Moyson , Hon Jung Liew , Marjan Diricx , Amit Kumar Sinha , Ronny Blust , Gudrun De Boeck
      In the present study, the combined effects of hypoxia and nutritional status were examined in common carp (Cyprinus carpio), a relatively hypoxia tolerant cyprinid. Fish were either fed or fasted and were exposed to hypoxia (1.5–1.8mg O2 L−1) at or slightly above their critical oxygen concentration during 1, 3 or 7days followed by a 7day recovery period. Ventilation initially increased during hypoxia, but fasted fish had lower ventilation frequencies than fed fish. In fed fish, ventilation returned to control levels during hypoxia, while in fasted fish recovery only occurred after reoxygenation. Due to this, C. carpio managed, at least in part, to maintain aerobic metabolism during hypoxia: muscle and plasma lactate levels remained relatively stable although they tended to be higher in fed fish (despite higher ventilation rates). However, during recovery, compensatory responses differed greatly between both feeding regimes: plasma lactate in fed fish increased with a simultaneous breakdown of liver glycogen indicating increased energy use, while fasted fish seemed to economize energy and recycle decreasing plasma lactate levels into increasing liver glycogen levels. Protein was used under both feeding regimes during hypoxia and subsequent recovery: protein levels reduced mainly in liver for fed fish and in muscle for fasted fish. Overall, nutritional status had a greater impact on energy reserves than the lack of oxygen with a lower hepatosomatic index and lower glycogen stores in fasted fish. Fasted fish transiently increased Na+/K+-ATPase activity under hypoxia, but in general ionoregulatory balance proved to be only slightly disturbed, showing that sufficient energy was left for ion regulation.

      PubDate: 2014-11-03T22:27:52Z
  • The magnitude of the naturally occurring isotopic enrichment of 13C in
           exhaled CO2 is directly proportional to exercise intensity in humans
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Marshall D. McCue , Celeste A. Passement , Miranda Rodriguez
      Due to various biochemical fractionation processes during lipid synthesis, the lipid molecules in the body contain substantially lower concentrations of 13C than the nonlipid molecules. Because of the isotopic differences between these two endogenous nutrient pools, any shift toward nonlipid fuel oxidation would be expected to increase in the δ13C of the exhaled breath. Interestingly, the possibility of whether or not an exercise-induced change actually occurs has been debated in literature for over two decades and researchers have still not reached a consensus. We measured ventilatory and metabolic variables before, during, and after exercise in forty-eight adults (n=25 females, n=23 males; 20.1±1.9years) assigned to either a resting treatment or one of three exercising treatments where they maintained a heart rate of 130, 150, or 170bpm for 56min. We found that the mean metabolic rates of the exercising groups increased 4.4-fold, 6.1-fold, and 7.7-fold above resting values, respectively. Exercise caused small increases in respiratory exchange ratios (e.g., from 0.83±0.08 to 0.86±0.10) indicative of increased carbohydrate oxidation, but these changes were too variable to be reliably correlated with exercise intensity. In contrast, the δ13C of the exhaled breath increased by 0.62±0.19‰, 1.14±0.29‰, and 1.79±0.50‰, respectively, for the three groups and was significantly correlated with the intensity of exercise. We also show that the isotopic difference of the lipid and nonlipids of the body is similar (~2.7‰) even when consuming bulk diets that are isotopically distinct (>8‰). If not corrected for, these exercise-induced changes in δ13C of the breath would be sufficiently large to skew the results of studies investigating the oxidative fates of exogenous nutritional supplements.

      PubDate: 2014-11-03T22:27:52Z
  • Fat mass and obesity associated (FTO) gene regulates gluconeogenesis in
           chicken embryo fibroblast cells
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Feng Guo , Yanhong Zhang , Chunxiao Zhang , Song Wang , Yingdong Ni , Ruqian Zhao
      Fat mass and obesity-associated (FTO) gene was found to be associated with energy homeostasis in mammals, yet the function of chicken FTO is less clear. In this study, chicken embryo fibroblast cells (DF-1) were transiently transfected to over-express (FTO+) or to knockdown (FTO−) the chicken FTO gene and were used for the functional analysis. FTO expression was significantly augmented in FTO+ cells while depressed in FTO− cells (P <0.05). FTO+ cells had significantly lower glucose yet higher lactic acid (LD) concentrations (P <0.05) in the culture media, which was associated with significantly up-regulated (P <0.05) mRNA expression of the rate-limiting gluconeogenic enzymes, glucose-6-phosphatase (G6PC) and the phosphoenolpyruvate carboxykinase-mitochondrial (PEPCK-m). The protein content and enzyme activity of G6PC were also significantly higher (P <0.05) in FTO+ cells. Moreover, CCAAT/enhancer-binding protein-beta (C/EBP-beta) and cAMP responsive element binding protein 1 (CREB1), which were found to transcriptionally regulate the expression of G6PC, were increased at the level of both mRNA (P <0.05) and protein (P <0.05) in FTO+ cells. ChIP analysis revealed significantly higher (P <0.05) binding of C/EBP-beta and phospho-CREB1 to G6PC gene promoter in FTO+ cells. In addition, the interaction of FTO and C/EBP-beta was significantly enhanced (P <0.05) in FTO+ cells. Opposite changes in G6PC expression and regulation were observed in FTO− cells. Our results indicate that chicken FTO regulates gluconeogenesis in DF-1 cells through enhanced transcriptional regulation of G6PC gene by C/EBP-beta and phospho-CREB1.

      PubDate: 2014-11-03T22:27:52Z
  • Baroreflex function in anurans from different environments
    • Abstract: Publication date: Available online 16 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Michael S. Hedrick , Kadi A. McNew , Dane A. Crossley II
      Anurans from terrestrial environments have an enhanced ability to maintain arterial blood pressure through lymph mobilization in response to desiccation or hemorrhage compared with semiaquatic or aquatic species. Because short term blood pressure homeostasis is regulated by arterial baroreceptors, we compared baroreflex function in three species of anurans that span a range of environments, dehydration tolerance and an ability to maintain arterial blood pressure with dehydration and hemorrhage. The cardiac limb of the baroreflex loop was studied using pharmacological manipulation of blood pressure with phenylephrine and sodium nitroprusside (20-200μgkg-1 each), and the resulting changes in heart rate were quantitatively analyzed using a four-parameter sigmoidal logistic function. Resting arterial blood pressure in the aquatic species, Xenopus laevis, was 3.6±0.3 kPa and was significantly less (P<0.005) than for the semiaquatic species, Lithobates catesbeianus (4.1±0.2 kPa), or the terrestrial species, Rhinella marina (4.7±0.2 kPa). Resting heart rates were equivalent in all three species. The maximal baroreflex gain was not different among the three species and ranged from 12.1 to 14.3 beats min-1 kPa-1 and occurred at mean arterial pressures (Pm) ranging from 3.0 to 3.8 kPa, which were slightly below the resting arterial blood pressures for each species. Mean arterial blood pressures at rest in the three species were near the saturation point of the baroreflex curve which provides the animals with a greater heart rate response range to hypotensive, rather than hypertensive, changes in blood pressure. This is consistent with the hypothesis that arterial baroreceptors are key sensory components that allow anurans to maintain arterial blood pressure possibly by mobilization of lymphatic return in response to hypotension.

      PubDate: 2014-10-17T10:00:22Z
  • mRNA levels of kisspeptins, kisspeptin receptors, and GnRH1 in the brain
           of chub mackerel during puberty
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Hirofumi Ohga , Hayato Adachi , Kojiro Matsumori , Ryoko Kodama , Mitsuo Nyuji , Sethu Selvaraj , Keitaro Kato , Shinji Yamamoto , Akihiko Yamaguchi , Michiya Matsuyama
      Kisspeptin (Kiss) and its cognate receptor (Kiss1R), implicated in the neuroendocrine control of GnRH secretion in mammals, have been proposed to be the key factors in regulating puberty. However, the mechanisms underlying the initiation of puberty in fish are poorly understood. The chub mackerel Scomber japonicus expresses two forms of Kiss (kiss1 and kiss2) and two Kiss receptor (kissr1 and kissr2) genes in the brain, which exhibit sexually dimorphic changes during the seasonal reproductive cycle. This indicates that the kisspeptin system plays an important role in gonadal recrudescence of chub mackerel; however, the involvement of the kisspeptin system in the pubertal process has not been identified. In the present study, we examined the mRNA expression of kiss1, kiss2, kissr1, kissr2, and gnrh1 (hypophysiotropic form) in the brain of a chub mackerel during puberty. In male fish, kiss2, kissr1 and kissr2 levels increased significantly at 14weeks post-hatch (wph), synchronously with an increase in type A spermatogonial populations in the testis; kiss2 and gnrh1 levels significantly increased at 22wph, just before the onset of meiosis in the testes. In female fish, kiss2 increased significantly at 14wph, synchronously with an increase in the number of perinucleolar oocytes in the ovary; kiss1 and kiss2 levels significantly increased concomitantly with an increase in the kissr1, kissr2, and gnrh1 levels at 24wph, just before the onset of vitellogenesis in oocytes. The present results suggest positive involvement of the kisspeptin–GnRH system in the pubertal process in the captive reared chub mackerel.

      PubDate: 2014-10-12T15:04:10Z
  • Seasonal variation in body mass, body temperature and thermogenesis in the
           Hwamei, Garrulax canorus
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Mei-Xiu Wu , Li-Meng Zhou , Li-Dan Zhao , Zhi-Jun Zhao , Wei-Hong Zheng , Jin-Song Liu
      The basal thermogenesis of birds is beginning to be viewed as a highly flexible physiological trait influenced by environmental fluctuations, particularly changes in ambient temperature (T a). Many birds living in regions with seasonal fluctuations in T a typically respond to cold by increasing their insulation and adjusting their metabolic rate. To understand these metabolic adaptations, body temperature (T b), metabolic rate (MR), thermal neutral zone (TNZ) and thermal conductance were measured within a range of temperatures from 5 to 40°C in free-living Hwamei, Garrulax canorus, in both winter and summer. Body mass was 61.2±0.3g in winter and 55.5±1.0g in summer, and mean T b was 41.6±0.1°C in winter and 42.3±0.1°C in summer. TNZ was between 28.3 and 35.1°C in winter and between 28.7 and 33.2°C in summer. The mean basal metabolic rate (BMR) within TNZ was 203.32±11.81ml O2 h−1 in winter and 168.99±6.45ml O2 h−1 in summer. Minimum thermal conductance was 3.73±0.09joulesg−1 h−1 °C−1 in winter and 3.26±0.06joulesg−1 h−1 °C−1 in summer. Birds caught in winter had higher body mass, MR, and more variable TNZ than those in summer. The increased winter BMR indicates improved ability to cope with cold and maintenance of a high T b. These results show that the Hwamei's metabolism is not constant, but exhibits pronounced seasonal phenotypic flexibility associated with maintenance of a high T b.

      PubDate: 2014-10-12T15:04:10Z
  • Detection of long-term influence of prenatal temperature stimulation on
           hypothalamic type-II iodothyronine deiodinase in juvenile female broiler
           chickens using a novel immunohistochemical amplification protocol
    • Abstract: Publication date: Available online 5 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Maaly Nassar , Ingrid Halle , Andreas Plagemann , Barbara Tzschentke
      It has been clearly shown that early environmental stimulation may have long-lasting influence on body functions. Because of the strong relationship between thermoregulation and other homeostatic linked physiological parameters, perinatal thermal manipulation will have also impact on other body functions like reproduction. As a maturation stimulant for later reproductive performance, hypothalamic type-2 iodothyronine deiodinase (Dio2) expression was investigated in 35 days old immature female broilers with and without embryonic temperature stimulation. For the first time, human-specific Dio2 primary antibodies combined with additional amplification enabled the immunohistochemical detection of hypothalamic Dio2 protein in birds. The novel protocol includes an additional amplification step involving swine-anti-rabbit/mouse/goat antibodies against both goat anti-Dio2 primary and rabbit anti-goat biotinylated secondary commercial antibodies in the standard diaminobenzidine protocol. But, significant Dio2 expression was exclusively found in perinatally short-term temperature stimulated hens. Caudal but not rostral hypothalamic slices revealed that elevating incubation temperature 1°C for 2 h daily, from day 18 of embryonic development until hatching, induced a statistical significant expression of Dio2 within the subcommisural organ and the median eminence. This ample expression of Dio2 protein within caudal but not rostral hypothalamic slices of embryonic temperature stimulated chickens, leads to the assumption of a novel physiological prospective for embryonic thermal manipulation involving the suppression of thyroid hormone and the boosting of hypothalamic Dio2-induced FSH secretion to considerably advance the age of photoinduced egg production. It could be also of practicable relevance for broiler breeder females, and needs further investigations.

      PubDate: 2014-10-08T14:27:11Z
  • Huddling reduces evaporative water loss in torpid Natterer’s bats,
           Myotis nattereri
    • Abstract: Publication date: Available online 5 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jan S. Boratyński , Craig K.R. Willis , Małgorzata Jefimow , Michał S. Wojciechowski
      Periodic arousals during hibernation consume most of the winter energy budget for hibernating mammals. Evaporative water loss (EWL) is thought to affect the frequency of arousals and thus energy balance might have dramatic implications for over-winter survival and fitness. We hypothesized that huddling affects EWL and energy expenditure in torpid mammals. We tested this hypothesis using bats as a model and predicted that, during torpor, EWL and energy expenditure of huddling individuals would be lower than in individuals that are not in a huddle. We measured EWL and metabolic rate of torpid Myotis nattereri (Kuhl, 1817) huddling in groups or roosting individually. Evaporative water loss in huddling individual bats was almost 30% lower than in solitary animals (P =0.03), even after correcting for the effects of metabolic rate. Our results suggest that conservation of water is a substantial benefit underlying huddling by bats during hibernation. Ultimately, huddling could reduce the total cost of hibernation by reducing the number of expensive periodic arousals from torpor caused by the need to supplement water.

      PubDate: 2014-10-08T14:27:11Z
  • Sequence, genomic organization and expression of ghrelin receptor in grass
           carp, Ctenopharyngodon idellus
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Wen-jing Cai , Xiao-chen Yuan , Yong-chao Yuan , Shou-qi Xie , Yuan Gong , Hang Su , Yang Qiao
      The growth hormone secretagogue-receptor (GHS-R) is an endogenous receptor for the gut hormone ghrelin. Here we report the identification and characterization of GHS-R1a in grass carp, Ctenopharyngodon idellus. The full-length GHS-R1a cDNA contained a 1803-bp coding domain sequence which encoded a peptide of 360 amino acid residues. Comparison analysis revealed that the amino acid sequences of GHS-R1a were highly conserved in vertebrates and shared 97% amino acid identity with zebrafish (Danio rerio), 96% with jian carp (Cyprinus carpio var. Jian) and 93% with goldfish (Carassius auratus). The GHS-R1a showed the highest level of mRNA expression in the pituitary, followed by the brain and liver, and the lowest expression was observed in the hindgut. Intraperitoneally injected with grass carp ghrelin (50, 100 and 150ng/g body weight (BW)), grass carp showed greater mRNA expression of GHS-R1a in the pituitary compared with saline injected at 0.5h postinjection. It was observed that food deprivation could promote the expression of ghrelin and GHS-R1a in the pituitary, demonstrating that nutritional status can influence the expression of both ghrelin and GHS-R1a in the pituitary. After a 2- or 4-week fast, plasma growth hormone (GH) increased, was positively correlated with ghrelin and GHS-R1a mRNA expression levels in the pituitary. These results suggested that the involvement of ghrelin/GHS-R1a systems in mediating the effects of nutritional status and ghrelin on growth processes in grass carp.

      PubDate: 2014-10-08T14:27:11Z
  • Temperature effects on baroreflex control of heart rate in the toad,
           Rhinella schneideri
    • Abstract: Publication date: Available online 28 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lucas A. Zena , Luciane H. Gargaglioni , Kênia C. Bícego
      For an adequate blood supply to support metabolic demands, vertebrates regulate blood pressure to maintain sufficient perfusion to avoid ischemia and other tissue damage like edema. Using a pharmacological approach (phenylephrine and sodium nitroprusside) we investigated baroreflex sensitivity at 15, 25, and 30°C in toads Rhinella schneideri. Baroreflex sensitivity presented a high thermal dependence (Q10 =1.9–4.1), and the HR–baroreflex curve was shifted up and to the right as temperature increased from 15 to 30°C. Baroreflex variables, namely, HR range, gain 50 (maximal gain) and normalized gain 50 increased 206, 235, and 160% from 15 to 30°C, respectively. The cardiac limb of the baroreflex response to pharmacological treatments was significantly blunted after full autonomic blockade. In addition, there was a clear baroreflex–HR response mainly to hypotension at all three temperatures tested. These findings indicate that toads present temperature dependence for cardiac limb of the barostatic response and the cardiac baroreflex response in R. schneideri is primarily hypotensive rather than hypertensive as well as crocodilians and mammals. Thus, the cardiac baroreflex compensation to changes in arterial pressure might present different patterns among amphibian species, since the previously reported bradycardic compensation to hypertension in some anurans was not observed in the toad used in the present study.

      PubDate: 2014-10-03T12:34:11Z
  • Diets labelled with 13C-starch and 15N-protein reveal daily rhythms of
           nutrient use in gilthead sea bream (Sparus aurata)
    • Abstract: Publication date: Available online 28 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Olga Felip , Josefina Blasco , Antoni Ibarz , Miguel Martín-Pérez , Jaume Fernández-Borràs
      Almost all functions in animals rely on daily rhythms, and mealtime can act as a rhythm-marker of nutrients assimilation and use. The aim of this research was to determine the effects of meal timing and food composition on carbohydrate use and protein retention of gilthead sea bream. Three groups of fish were fed twice a day (at 10am and at 5pm) for two months with two alternating diets: a commercial diet (Cd) and a high-carbohydrate, low-protein diet (Ed). The Ed/Cd group received the Ed diet in the morning and the Cd diet in the afternoon, and the Cd/Ed group received these diets in the reverse order. The Cd/Cd group only received the commercial diet (control group). After 56days of the feeding period, two force-feeding experiments (PF1 and PF2 for all three groups) measured the fate of a single meal labelled with 15N-protein and 13C-starch through the retention of both isotopes in the main organs and tissue reserves. In PF1 fish were fed at 10am (morning mealtime), and in PF2 at 5pm (afternoon mealtime). Fish were sampled at the next two mealtimes (PF1: 7 and 24h post-feeding, PF2: 17 and 24h post-feeding). Recovery of the labelled nutrients differed according to, first, the dietary regime, and second, the last meal received (Cd or Ed). Although the fish in the regimes with Ed diet received less protein each day, they compensated with higher protein retention combined with more use of carbohydrates for energy. Nevertheless, carbohydrates were not used as efficiently in the afternoon as in the morning. So, the use of carbohydrate for energy production and protein for growth can be improved by adjusting diet composition and mealtime.

      PubDate: 2014-10-03T12:34:11Z
  • Vasodilatory effects of homologous adrenomedullin 2 and adrenomedullin 5
           in isolated blood vessels of two species of eel
    • Abstract: Publication date: Available online 2 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Melissa S. Cameron , Shigenori Nobata , Yoshio Takei , John A. Donald
      In mammals, adrenomedullin (AM) is a potent vasodilator through signalling pathways that involve the endothelium. In teleost fishes, a family of five AMs are present (AM1/4, AM2/3 and AM5) with four homologous AMs (AM1, AM2/3 and AM5) recently cloned from the Japanese eel, Anguilla japonica. Both AM2 and AM5 have been shown to be strong in vivo vasodepressors in eel, but the mechanism of action of homologous AMs on isolated blood vessels has not been examined in teleost fish. In this study, both eel AM2 and AM5 caused a marked vasodilation of the dorsal aorta. However, only AM5 consistently dilated the small gonadial artery in contrast to AM2 that had no effect in most preparations. Neither AM2 nor AM5 had any effect when applied to the first afferent branchial artery; in contrast, eel ANP always caused a large vasodilation of the branchial artery. In the dorsal aorta, indomethacin significantly reduced the AM2 vasodilation, but had no effect on the AM5 vasodilation. In contrast, removal of the endothelium significantly enhanced the AM5 vasodilation only. In the gonadial artery, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) significantly reduced the AM5 vasodilation suggesting a role for soluble guanylyl cyclase in the dilation, but L-NNA and removal of the endothelium had no effect. The results of this study indicate that AM2 and AM5 have distinct vasodilatory effects that may be due to the peptides signalling via different receptors to regulate vascular tone in eel.

      PubDate: 2014-10-03T12:34:11Z
  • The effect of temperature and body size on metabolic scope of activity in
           juvenile Atlantic cod Gadus morhua L.
    • Abstract: Publication date: Available online 30 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Bjørn Tirsgaard , Jane W. Behrens , John F. Steffensen
      Changes in ambient temperature affect the physiology and metabolism and thus the distribution of fish. In this study we used intermittent flow respirometry to determine the effect of temperature (2, 5, 10, 15 and 20°C) and wet body mass (BM) (~30–460g) on standard metabolic rate (SMR, mgO2 h−1), maximum metabolic rate (MMR, mgO2 h−1) and metabolic scope (MS, mgO2 h−1) of juvenile Atlantic cod. SMR increased with BM irrespectively of temperature, resulting in an average scaling exponent of 0.87 (0.82–0.92). Q10 values were 1.8–2.1 at temperatures between 5 and 15°C but higher (2.6–4.3) between 2 and 5°C and lower (1.6–1.4) between 15 and 20°C in 200 and 450g cod. MMR increased with temperature in the smallest cod (50g) but in the larger cod MMR plateaued between 10, 15 and 20°C. This resulted in a negative correlation between the optimal temperature for MS (Topt) and BM, Topt being respectively 14.5, 11.8 and 10.9°C in a 50, 200 and 450g cod. Irrespective of BM cold water temperatures resulted in a reduction (30–35%) of MS whereas the reduction of MS at warm temperatures was only evident for larger fish (200 and 450g), caused by plateauing of MMR at 10°C and above. Warm temperatures thus seem favourable for smaller (50g) juvenile cod, but not larger for conspecifics (200 and 450g).

      PubDate: 2014-10-03T12:34:11Z
  • Life stage-related differences in fatty acid composition of an obligate
           ectoparasite, the deer ked (Lipoptena cervi)—Influence of blood
           meals and gender
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anne-Mari Mustonen , Reijo Käkelä , Tommi Paakkonen , Petteri Nieminen
      Metamorphosis and diet often influence fatty acid (FA) signatures (FAS) of insects. We investigated FAS in a hematophagous ectoparasite, the deer ked (Lipoptena cervi). Deer keds shed their wings upon attachment on the host and, thus, the FAS of an individual blood-fed imago/pupa in the fur of its host can be traced back to the blood FA profile of a single moose (Alces alces). Host blood and different life stages of deer keds were investigated for FA by gas chromatography. The FAS of life stages resembled each other more closely than the diet. Blood meals modified the FAS of both sexes but the FAS of the blood-fed females were closer to those of the prepupae/pupae. The parasitizing males had higher proportions of major saturated FA (SFA) and polyunsaturated FA (PUFA) than the females, which contained more monounsaturated FA (MUFA) with higher ratios of n-3/n-6 PUFA and unsaturated FA (UFA)/SFA. The proportions of 16:1n-7 were <1% in the blood but 18% (males) and 29% (females) in the blood-fed keds. Allocation of lipids to offspring by the females and possible accumulation of PUFA in male reproductive organs may have induced these sex-related differences. MUFA percentages and UFA/SFA ratios increased while SFA and many PUFA decreased from the reproducing females to the pupae. The diapausing pupae displayed lowered n-3/n-6 PUFA ratios and could have mobilized 16:0 and 18:3n-3 for the most fundamental metabolic processes. In conclusion, FAS are modified through the life stages of the deer ked possibly due to their different requirements.

      PubDate: 2014-09-20T08:14:15Z
  • Taking their breath away: Metabolic responses to low-oxygen levels in
           anchialine shrimps (Crustacea: Atyidae and Alpheidae)
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Justin C. Havird , Rebecca C. Vaught , Jeffrey R. Weeks , Yoshihisa Fujita , Michio Hidaka , Scott R. Santos , Raymond P. Henry
      Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial pressures decrease, but when a critical low level is reached, ventilation and aerobic metabolism shut down. Cave-adapted animals, including crustaceans, often show a reduced metabolic rate possibly owing in part to the hypoxic nature of such environments. However, metabolic rates have not been thoroughly explored in crustaceans from anchialine habitats (coastal ponds and caves), which can experience variable oxygenic regimes. Here, an atypical oxy-conforming pattern of oxygen uptake is reported in the Hawaiian anchialine atyid Halocaridina rubra, along with other unusual metabolic characteristics. Ventilatory rates are near-maximal in normoxia and did not increase appreciably as PO2 declined, resulting in a decline in VO2 during progressive hypoxia. Halocaridina rubra maintained in anoxic waters survived for seven days (the duration of the experiment) with no measureable oxygen uptake, suggesting a reliance on anaerobic metabolism. Supporting this, lactate dehydrogenase activity was high, even in normoxia, and oxygen debts were quickly repaid by an unusually extreme increase in oxygen uptake upon exposure to normoxia. In contrast, four related anchialine shrimp species from the Ryukyu Islands, Japan, exhibited physiological properties consistent with previously studied crustaceans. The unusual respiratory patterns found in H. rubra are discussed in the context of a trade-off in gill morphology for osmoregulatory ion transport vs. diffusion of respiratory gasses. Future focus on anchialine species may offer novel insight into the diversity of metabolic responses to hypoxia and other physiological challenges experienced by crustaceans.

      PubDate: 2014-09-20T08:14:15Z
  • Editorial Board
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178

      PubDate: 2014-09-20T08:14:15Z
  • Critical windows in embryonic development: Shifting incubation
           temperatures alter heart rate and oxygen consumption of Lake Whitefish
           (Coregonus clupeaformis) embryos and hatchlings
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): J. Eme , C.A. Mueller , R.G. Manzon , C.M. Somers , D.R. Boreham , J.Y. Wilson
      Critical windows are periods of developmental susceptibility when the phenotype of an embryonic, juvenile or adult animal may be vulnerable to environmental fluctuations. Temperature has pervasive effects on poikilotherm physiology, and embryos are especially vulnerable to temperature shifts. To identify critical windows, we incubated whitefish embryos at control temperatures of 2°C, 5°C, or 8°C, and shifted treatments among temperatures at the end of gastrulation or organogenesis. Heart rate (fH) and oxygen consumption (V. o 2) were measured across embryonic development, and V. o 2 was measured in 1day-old hatchlings. Thermal shifts, up or down, from initial incubation temperatures caused persistent changes in fH and V. o 2 compared to control embryos measured at the same temperature (2°C, 5°C, or 8°C). Most prominently, when embryos were measured at organogenesis, shifting incubation temperature after gastrulation significantly lowered V. o 2 or fH. Incubation at 2°C or 5°C through gastrulation significantly lowered V. o 2 (42% decrease) and fH (20% decrease) at 8°C, incubation at 2°C significantly lowered V. o 2 (40% decrease) and fH (30% decrease) at 5°C, and incubation at 5°C and 8°C significantly lowered V. o 2 at 2°C (27% decrease). Through the latter half of development, V. o 2 and fH in embryos were not different from control values for thermally shifted treatments. However, in hatchlings measured at 2°C, V. o 2 was higher in groups incubated at 5°C or 8°C through organogenesis, compared to 2°C controls (43 or 65% increase, respectively). Collectively, these data suggest that embryonic development through organogenesis represents a critical window of embryonic and hatchling phenotypic plasticity. This study presents an experimental design that identified thermally sensitive periods for fish embryos.

      PubDate: 2014-09-20T08:14:15Z
  • Effects of salinity on metabolic rate and branchial expression of genes
           involved in ion transport and metabolism in Mozambique tilapia
           (Oreochromis mossambicus)
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Aris Zikos , Andre P. Seale , Darren T. Lerner , E. Gordon Grau , Keith E. Korsmeyer
      This study investigated the effects of two rearing salinities, and acute salinity transfer, on the energetic costs of osmoregulation and the expression of metabolic and osmoregulatory genes in the gill of Mozambique tilapia. Using automated, intermittent-flow respirometry, measured standard metabolic rates (SMRs) of tilapia reared in seawater (SW, 130mgO2 kg−1 h−1) were greater than those reared in fresh water (FW, 103mgO2 kg−1 h−1), when normalized to a common mass of 0.05kg and at 25±1°C. Transfer from FW to 75% SW increased SMR within 18h, to levels similar to SW-reared fish, while transfer from SW to FW decreased SMR to levels similar to FW-reared fish. Branchial gene expression of Na+–K+–2Cl− cotransporter (NKCC), an indicator of SW-type mitochondria-rich (MR) cells, was positively correlated with SMR, while Na+–Cl− cotransporter (NCC), an indicator of FW-type MR cells, was negatively correlated. Principal Components Analysis also revealed that branchial expression of cytochrome c oxidase subunit IV (COX-IV), glycogen phosphorylase (GP), and a putative mitochondrial biogenesis regulator in fish, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), were correlated with a higher SMR, plasma osmolality, and environmental salinity, while expression of glycogen synthase (GS), PGC-1β, and nuclear respiratory factor 1 (NRF-1) had negative correlations. These results suggest that the energetic costs of osmoregulation are higher in SW than in FW, which may be related to the salinity-dependent differences in osmoregulatory mechanisms found in the gills of Mozambique tilapia.

      PubDate: 2014-09-20T08:14:15Z
  • Kisspeptin regulates the somatic growth-related factors of the cinnamon
           clownfish Amphiprion melanopus
    • Abstract: Publication date: Available online 15 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Na Na Kim , Young-Ung Choi , Heung-Sik Park , Choi Cheol Young Choi
      This study aimed to test the effects of kisspeptin (Kiss) on somatic growth in the cinnamon clownfish Amphiprion melanopus. We investigated the effects of Kiss treatment on the growth by measuring the mRNA expressions of the growth hormone (GH), insulin-like growth hormone factor (IGF-I), somatolactin (SL), and melatonin receptor (MT). The expression levels of GH and SL of the pituitary and IGF-I of the liver increased after Kiss treatment (in vivo and in vitro). In addition, the MT mRNA expression increased in the pituitary and brain after Kiss treatment (in vivo and in vitro). These results support the hypothesis that Kiss directly regulates the somatic growth-related factors, such as GH, SL, and MT, and IGF-I in the cinnamon clownfish. Further, injection of Kiss resulted in significantly higher levels of plasma melatonin than that in the control. We, therefore, conclude that Kiss plays a role in modulating growth and artificially induced rapid growth in cinnamon clownfish.

      PubDate: 2014-09-16T06:57:55Z
  • Effects of hypoxia on ionic regulation, glycogen utilization and
           antioxidative ability in the gills and liver of the aquatic air-breathing
           fish Trichogaster microlepis
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chun-Yen Huang , Hui-Chen Lin , Cheng-Huang Lin
      We examined the hypothesis that Trichogaster microlepis, a fish with an accessory air-breathing organ, uses a compensatory strategy involving changes in both behavior and protein levels to enhance its gas exchange ability. This compensatory strategy enables the gill ion-regulatory metabolism to maintain homeostasis during exposure to hypoxia. The present study aimed to determine whether ionic regulation, glycogen utilization and antioxidant activity differ in terms of expression under hypoxic stresses; fish were sampled after being subjected to 3 or 12 h of hypoxia and 12 h of recovery under normoxia. The air-breathing behavior of the fish increased under hypoxia. No morphological modification of the gills was observed. The expression of carbonic anhydrase II did not vary among the treatments. The Na+/K+-ATPase enzyme activity did not decrease, but increases in Na+/K+-ATPase protein expression and ionocyte levels were observed. The glycogen utilization increased under hypoxia as measured by glycogen phosphorylase protein expression and blood glucose level, whereas the glycogen content decreased. The enzyme activity of several components of the antioxidant system in the gills, including catalase, glutathione peroxidase, and superoxidase dismutase, increased in enzyme activity. Based on the above data, we concluded that T. microlepis is a hypoxia-tolerant species that does not exhibit ion-regulatory suppression but uses glycogen to maintain energy utilization in the gills under hypoxic stress. Components of the antioxidant system showed increased expression under the applied experimental treatments.

      PubDate: 2014-09-16T06:57:55Z
  • Antiviral activity of the inducible humoral immunity and its suppression
           by eleven BEN family members encoded in Cotesia plutellae bracovirus
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ramjan Ali , Yonggyun Kim
      Upon parasitization by some endoparasitoids, polydnaviruses (PDVs) play a crucial role in inducing host immunosuppression. This study reports a novel immunosuppressive activity against humoral immune responses by BEN family genes encoded in Cotesia plutellae bracovirus (CpBV). A total of 11 BEN family members are encoded in 10 different CpBV DNA segments. When the CpBV segments were individually injected, specific BEN genes were expressed and suppressed the expression of antimicrobial peptide (AMP) and prophenoloxidase genes following bacterial challenge. The suppressive activities of the BEN genes were reversed by injection of the double-stranded RNA (dsRNA) specific to each BEN gene. The suppression of the AMP gene expressions by the BEN genes were also confirmed using an inhibition zone assay against Gram-positive and -negative bacterial growth. The significance of the suppressive activity of BEN genes against humoral immune responses was analyzed in terms of suppression of antiviral activity by the host humoral immunity. When CpBV was incubated with the plasma obtained from the larvae challenged with bacteria, the immunized plasma severely impaired the expression activity of the viral genes. However, an expression of BEN gene significantly rescued the viral gene expression by suppressing humoral immune response. These results suggest that BEN family genes of CpBV play a crucial role in defending the antiviral response of the parasitized Plutella xylostella by inhibiting humoral immune responses.

      PubDate: 2014-09-16T06:57:55Z
  • Seasonal variations in reproductive activity of the blue crab, Callinectes
           sapidus: Vitellogenin expression and levels of vitellogenin in the
           hemolymph during ovarian development
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Willawan Thongda , J. Sook Chung , Naoaki Tsutsui , Nilli Zmora , Anna Katenta
      In general, season affects the physiology and behavior of most animals. Warmer temperatures accelerate growth and reproduction of ectotherms, whereas these processes are slowed or halted in colder temperatures. Female blue crabs, Callinectes sapidus inhabiting the Chesapeake Bay, exhibit a seasonal migratory behavior that is closely tied with spawning and the release of larvae. To better understand reproductive activities of the migratory adult females, we examined two reproductive parameters of these crabs sampled monthly (April-December, 2006): the levels of vitellogenin (VtG) in the hemolymph and VtG expression in the hepatopancreas and ovary. The full-length cDNA of VtG (CasVtG-ova) has been isolated from the ovary. The putative CasVtG sequence found in the ovary is >99% identical to that of the hepatopancreas and is related most closely to the sequences reported in other crab species. In female C. sapidus, the hepatopancreas produces over 99% of the total VtG toward the ovarian development. Ovarian stages 2 and 3 in the sampled females are characterized by significant high levels of VtG in hemolymph and VtG expression in both the hepatopancreas and ovary. However, during the southbound migration in fall, females at ovarian stages 2 and 3 have decreased VtG levels, compared to those in spring and summer. The decreased vitellogenesis activity during the fall migration suggests seasonal adaptation to ensure successful spawning and the larval release.

      PubDate: 2014-09-16T06:57:55Z
  • High blood oxygen affinity in the air-breathing swamp eel Monopterus albus
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Christian Damsgaard , Inge Findorf , Signe Helbo , Yigit Kocagoz , Rasmus Buchanan , Do Thi Thanh Huong , Roy E. Weber , Angela Fago , Mark Bayley , Tobias Wang
      The Asian swamp eel (Monopterus albus, Zuiew 1793) is a facultative air-breathing fish with reduced gills. Previous studies have shown that gas exchange seems to occur across the epithelium of the buccopharyngeal cavity, the esophagus and the integument, resulting in substantial diffusion limitations that must be compensated by adaptations in others steps of the O2 transport system to secure adequate O2 delivery to the respiring tissues. We therefore investigated O2 binding properties of whole blood, stripped hemoglobin (Hb), two major isoHb components and the myoglobin (Mb) from M. albus. Whole blood was sampled using indwelling catheters for blood gas analysis and determination of O2 equilibrium curves. Hb was purified to assess the effects of endogenous allosteric effectors, and Mb was isolated from heart and skeletal muscle to determine its O2 binding properties. The blood of M. albus has a high O2 carrying capacity [hematocrit (Hct) of 42.4±4.5%] and binds O2 with an unusually high affinity (P 50 =2.8±0.4mmHg at 27°C and pH7.7), correlating with insensitivity of the Hb to the anionic allosteric effectors that normally decrease Hb-O2 affinity. In addition, Mb is present at high concentrations in both heart and muscle (5.16±0.99 and 1.08±0.19mg ∙ g wet tissue-1, respectively). We suggest that the high Hct and high blood O2 affinity serve to overcome the low diffusion capacity in the relatively inefficient respiratory surfaces, while high Hct and Mb concentration aid in increasing the O2 flux from the blood to the muscles.

      PubDate: 2014-09-12T05:16:16Z
  • Pigment granule translocation in red ovarian chromatophores from the
           palaemonid shrimp Macrobrachium olfersi (Weigmann, 1836): Functional roles
           for the cytoskeleton and its molecular motors
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Sarah Ribeiro Milograna , Márcia Regina Ribeiro , Munira Muhammad Abdel Baqui , John Campbell McNamara
      The binding of red pigment concentrating hormone (RPCH) to membrane receptors in crustacean chromatophores triggers Ca2+/cGMP signaling cascades that activate cytoskeletal motors, driving pigment granule translocation. We investigate the distributions of microfilaments and microtubules and their associated molecular motors, myosin and dynein, by confocal and transmission electron microscopy, evaluating a functional role for the cytoskeleton in pigment translocation using inhibitors of polymer turnover and motor activity in vitro. Microtubules occupy the chromatophore cell extensions whether the pigment granules are aggregated or dispersed. The inhibition of microtubule turnover by taxol induces pigment aggregation and inhibits re-dispersion. Phalloidin-FITC actin labeling, together with tannic acid fixation and ultrastructural analysis, reveals that microfilaments form networks associated with the pigment granules. Actin polymerization induced by jasplaquinolide strongly inhibits RPCH-induced aggregation, causes spontaneous pigment dispersion, and inhibits pigment re-dispersion. Inhibition of actin polymerization by latrunculin-A completely impedes pigment aggregation and re-dispersion. Confocal immunocytochemistry shows that non-muscle myosin II (NMMII) co-localizes mainly with pigment granules while blebbistatin inhibition of NMMII strongly reduces the RPCH response, also inducing spontaneous pigment dispersion. Myosin II and dynein also co-localize with the pigment granules. Inhibition of dynein ATPase by erythro-9-(2-hydroxy-3-nonyl) adenine induces aggregation, inhibits RPCH-triggered aggregation, and inhibits re-dispersion. Granule aggregation and dispersion depend mainly on microfilament integrity although microtubules may be involved. Both cytoskeletal polymers are functional only when subunit turnover is active. Myosin and dynein may be the molecular motors that drive pigment aggregation. These mechanisms of granule translocation in crustacean chromatophores share various features with those of vertebrate pigment cells.

      PubDate: 2014-09-12T05:16:16Z
  • Osmoregulation and branchial plasticity after acute freshwater transfer in
           red drum, Sciaenops ocellatus
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Caroline J. Watson , Wiolene M. Nordi , Andrew J. Esbaugh
      Red drum, Sciaenops ocellatus, is an estuarine-dependent fish species commonly found in the Gulf of Mexico and along the coast of the southeastern United States. This economically important species has demonstrated freshwater tolerance; however, the physiological mechanisms and costs related to freshwater exposure remain poorly understood. The current study therefore investigated the physiological response of red drum using an acute freshwater transfer protocol. Plasma osmolality, Cl−, Mg2+ and Ca2+ were all significantly reduced by 24h post-transfer; Cl− and Mg2+ recovered to control levels by 7days post-transfer. No effect of transfer was observed on muscle water content; however, muscle Cl− was significantly reduced. Interestingly, plasma and muscle Na+ content was unaffected by freshwater transfer. Intestinal fluid was absent by 24h post-transfer indicating cessation of drinking. Branchial gene expression analysis showed that both CFTR and NKCC1 exhibited significant down-regulation at 8 and 24h post-transfer, respectively, although transfer had no impact on NHE2, NHE3 or Na+, K+ ATPase (NKA) activity. These general findings are supported by immunohistochemical analysis, which revealed no apparent NKCC containing cells in the gills at 7days post transfer while NKA cells localization was unaffected. The results of the current study suggest that red drum can effectively regulate Na+ balance upon freshwater exposure using already present Na+ uptake pathways while also down-regulating ion excretion mechanisms.

      PubDate: 2014-09-12T05:16:16Z
  • The role of metabolism for understanding the altitudinal segregation
           pattern of two potentially interacting lizards
    • Abstract: Publication date: Available online 3 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anamarija Žagar , Tatjana Simčič , Miguel A. Carretero , Al Vrezec
      Sympatric species belonging to the same ecological guild, that exhibit partial altitudinal segregation, can potentially interact when in areas of syntopic occurrence. Besides general species’ ecology, physiology can provide elusive answers about species interactions reflected in altitudinal patterns. Lizards Podarcis muralis and Iberolacerta horvathi subject to the rule of partial altitudinal segregation, while they strongly resemble in overall morphology and ecology (diet, daily and seasonal activity pattern), but show some degree of physiological dissimilarity. They have similar mean preferred body temperatures and its pattern of seasonal and daily variation but differ in the magnitude of seasonal variation. Since in ectotherms metabolism is highly dependent on body temperature, thermoregulation is expected to directly affect their metabolism. We compared metabolic rates of adult males of studied species from an area of sympatry, measured under two temperature regimes (20°C and 28°C) in search of interspecific differences in the response of metabolism to temperature change. Both species increased metabolic rates with temperature with a similar pattern. Secondly, we compared measures of electron transport activity from their tail tissues which provide values of species potential metabolic activity (enzymatic capacity). Species clearly differed in potential metabolic activity; I. horvathi attains higher values than P. muralis. No interspecific difference was detected in how species exploited this potential (calculated from the ratio of electron transport activity and metabolic rates). However, measures of electron transport activity showed higher potential metabolic activity of I. horvathi which together with the ability to thermoregulate more precisely could represent a higher competitive advantage over P. muralis in thermally more restrictive environments such as higher altitudes. Understanding of metabolism seems to provide valuable information for understanding recent distributional patterns as well as species interactions.

      PubDate: 2014-09-06T03:54:40Z
  • The actions of the renin–angiotensin system on cardiovascular and
           osmoregulatory function in embryonic chickens (Gallus gallus domesticus)
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Casey A. Mueller , Dane A. Crossley II , Warren W. Burggren
      Using embryonic chickens (Gallus gallus domesticus), we examined the role of the renin–angiotensin system (RAS) in cardiovascular and osmotic homeostasis through chronic captopril, an angiotensin-converting enzyme (ACE) inhibitor. Captopril (5mgkg−1 embryo wet mass) or saline (control) was delivered via the egg air cell daily from embryonic day 5–18. Mean arterial pressure (MAP), heart rate (ƒH), fluid osmolality and ion concentration, and embryonic and organ masses were measured on day 19. Exogenous angiotensin I (ANG I) injection did not change MAP or ƒH in captopril-treated embryos, confirming ACE inhibition. Captopril-treated embryos were significantly hypotensive, with MAP 15% lower than controls, which we attributed to the loss of vasoconstrictive ANG II action. Exogenous ANG II induced a relatively greater hypertensive response in captopril-treated embryos compared to controls. Changes in response to ANG II following pre-treatment with phentolamine (α-adrenergic antagonist) indicated a portion of the ANG II response was due to circulating catecholamines in captopril-treated embryos. An increase in MAP and ƒH in response to hexamethonium indicated vagal tone was also increased in the absence of ACE activity. Captopril-treated embryos had lower osmolality, lower Na+ and higher K+ concentration in the blood, indicating osmoregulatory changes. Larger kidney mass in captopril-treated embryos suggests disrupting the RAS may stimulate kidney growth by decreasing resistance at the efferent arteriole and increasing the fraction of cardiac output to the kidneys. This study suggests that the RAS, most likely through ANG II action, influences the development of the cardiovascular and osmoregulatory systems.

      PubDate: 2014-09-06T03:54:40Z
  • Cold hardiness and deacclimation of overwintering Papilio zelicaon pupae
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Caroline M. Williams , Annegret Nicolai , Laura V. Ferguson , Mark A. Bernards , Jessica J. Hellmann , Brent J. Sinclair
      Seasonally-acquired cold tolerance can be reversed at warm temperatures, leaving temperate ectotherms vulnerable to cold snaps. However, deacclimation, and its underlying mechanisms, has not been well-explored in insects. Swallowtail butterflies are widely distributed but in some cases their range is limited by low temperature and their cold tolerance is seasonally acquired, implying that they experience mortality resulting from deacclimation. We investigated cold tolerance and hemolymph composition of Anise swallowtail (Papilio zelicaon) pupae during overwintering in the laboratory, and after four days exposure to warm temperatures in spring. Overwintering pupae had supercooling points around −20.5°C and survived brief exposures to −30°C, suggesting partial freeze tolerance. Overwintering pupae had hemolymph osmolality of approximately 920mOsm, imparted by high concentrations of glycerol, K+ and Na+. After exposure to spring warming, supercooling points increased to approximately −17°C, and survival of a 1h exposure to −20°C decreased from 100% to 0%. This deacclimation was associated with decreased hemolymph osmolality and reduced glycerol, trehalose, Na+ and Ca2+ concentrations. We compared cold tolerance of pupae to weather conditions at and beyond the species' northern range boundary. Minimum temperatures at the range boundary approached the lower lethal temperature of pupae, and were colder north of the range, suggesting that cold hardiness may set northern range limits. Minimum temperatures following warm snaps were likely to cause mortality in at least one of the past three years. Cold snaps in the spring are increasing in frequency as a result of global climate change, so are likely to be a significant source of mortality for this species, and other temperate ectotherms.

      PubDate: 2014-09-06T03:54:40Z
  • The absence of ion-regulatory suppression in the gills of the aquatic
           air-breathing fish Trichogaster lalius during oxygen stress
    • Abstract: Publication date: Available online 3 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chun-Yen Huang , Hsueh-Hsi Lin , Cheng-Huang Lin , Hui-Chen Lin
      The strategy for most teleost to survive in hypoxic or anoxic conditions is to conserve energy expenditure, which can be achieved by suppressing energy-consuming activities such as ion regulation. However, an air-breathing fish can cope with hypoxic stress using a similar adjustment, as in most teleost, or by enhancing gas exchange ability, both behaviorally and physiologically. In the present study, we examined Trichogaster lalius, an air-breathing fish without apparent gill modification, for their gill ion-regulatory abilities and glycogen utilization under a hypoxic treatment. We recorded air-breathing frequency, branchial morphology, and the expression of ion-regulatory proteins (Na+/K+-ATPase and vacuolar-type H+-ATPase) in the 1st and 4th gills and labyrinth organ (LO), and the expression of glycogen utilization (GP, glycogen phosphorylase protein expression and glycogen content) and other protein responses (catalase, CAT; carbonic anhydranse II, CAII; heat shock protein 70, HSP70; hypoxia-inducible factor-1α, HIF-1α; proliferating cell nuclear antigen, PCNA; superoxidase dismutase, SOD) in the gills of T. lalius after 3days in hypoxic and restricted conditions. In contrast to our study on other air-breathing species, no morphological modification of the 1st and 4th gills was observed. The air-breathing behavior of the fish and CAII protein expression both increased under hypoxia. Ion-regulatory abilities were not suppressed in the hypoxic or restricted groups, but glycogen utilization, indicated as GP protein expression, was enhanced within the groups. The expression of HIF-1α, HSP70 and PCNA did not vary among the treatments. Regarding the antioxidant system, decreased CAT enzyme activity was observed among the groups. In conclusion, during hypoxic stress, T. lalius did not significantly reduce energy consumption but enhanced gas exchange ability and glycogen expenditure.

      PubDate: 2014-09-06T03:54:40Z
  • Assessing stimulus and subject influences on auditory evoked potentials
           and their relation to peripheral physiology in green treefrogs (Hyla
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Nathan P. Buerkle , Katrina M. Schrode , Mark A. Bee
      Anurans (frogs and toads) are important models for comparative studies of communication, auditory physiology, and neuroethology, but to date, most of our knowledge comes from in-depth studies of a relatively small number of model species. Using the well-studied green treefrog (Hyla cinerea), this study sought to develop and evaluate the use of auditory evoked potentials (AEPs) as a minimally invasive tool for investigating auditory sensitivity in a larger diversity of anuran species. The goals of the study were to assess the effects of frequency, signal level, sex, and body size on auditory brainstem response (ABR) amplitudes and latencies, characterize gross ABR morphology, and generate an audiogram that could be compared to several previously published audiograms for green treefrogs. Increasing signal level resulted in larger ABR amplitudes and shorter latencies, and these effects were frequency dependent. There was little evidence for an effect of sex or size on ABRs. Analyses consistently distinguished between responses to stimuli in the frequency ranges of the three previously-described populations of afferents that innervate the two auditory end organs in anurans. The overall shape of the audiogram shared prominent features with previously published audiograms. This study highlights the utility of AEPs as a valuable tool for the study of anuran auditory sensitivity.

      PubDate: 2014-09-06T03:54:40Z
  • To each its own: Thermoregulatory strategy varies among neonatal polar
    • Abstract: Publication date: Available online 21 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Linnea E. Pearson , Heather E.M. Liwanag , Mike O. Hammill , Jennifer M. Burns
      Cold environmental conditions and small body size often promote heat loss and may create thermoregulatory challenges for marine mammals born in polar regions. However, among polar-born phocid seal species there are variations in physical attributes and environmental conditions at birth, allowing for an interesting contrast in thermoregulatory strategy. We compared aspects of thermoregulatory strategies including morphometrics, sculp attributes (conductivity and resistance), nonshivering thermogenesis (NST via uncoupling protein 1; UCP1), and muscle thermogenesis (via enzyme activity) in neonatal harp (Pagophilus groenlandicus), hooded (Cystophora cristata), and Weddell seals (Leptonychotes weddellii). Harp seals are the smallest at birth (9.8±0.7kg), rely on lanugo (82.49±3.70% of thermal resistance), and are capable of NST through expression of UCP1 in brown adipose tissue (BAT). In contrast, hooded seal neonates (26.8±1.3kg) have 2.06±0.23cm of blubber, accounting for 38.19±6.07% of their thermal resistance. They are not capable of NST, as UCP1 is not expressed. The large Weddell seal neonates (31.5±4.9kg) rely on lanugo (89.85±1.25% of thermal resistance) like harp seals, but no evidence of BAT was found. Muscle enzyme activity was highest in Weddell seal neonates, suggesting they rely primarily on muscle thermogenesis. Similar total thermal resistance, combined with the marked differences in thermogenic capacity of NST and ST among species, strongly supports the idea that thermoregulatory strategy in neonate phocids is more closely tied to pups' surface area to volume ratio (SA:V) and potential for early water immersion rather than mass and ambient environmental conditions.

      PubDate: 2014-09-02T02:29:30Z
  • Testing the heat-invariant and cold-variability tolerance hypotheses
           across geographic gradients
    • Abstract: Publication date: Available online 23 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Francisco Bozinovic , María J.M. Orellana , Sebastián I. Martel , José M. Bogdanovich
      Changes in temperature across geographic gradients can occur on a wide temporal range, from fluctuations within hours as a result of day-night to those over many years. These events will drive many organisms towards their physiological limits of thermal tolerance. Recently, many reports support a limited scope for adaptive evolutionary responses to high temperatures, meaning a conserved heat tolerance among ectotherms in general. We address this problem and tested the heat and cold tolerance invariant–variant hypotheses in terrestrial isopods. We studied five different populations of Porcellio laevis and three populations of Porcellio scaber, spanning 30° S latitudinal gradient in Chile. The heat tolerance of woodlice was conserved with little variation along latitude and environmental temperatures, but cold tolerance decreases significantly with environmental temperatures and latitudes. Indeed, a significant and negative correlation was observed between cold tolerance and latitude. Also, significant and positive correlations were observed among cold tolerance and environmental temperatures. Conversely, heat tolerance was not significantly correlated with any of the environmental temperatures tested neither with latitude. This macrophysiological pattern indicated that heat and cold-tolerances of species and populations not always change across geographical gradients meaning that thermal tolerance responses to high temperatures may be evolutionary constrained.

      PubDate: 2014-09-02T02:29:30Z
  • Hearts of some Antarctic fishes lack mitochondrial creatine kinase
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): K.M. O'Brien , I.A. Mueller , J.I. Orczewska , K.R. Dullen , M. Ortego
      Creatine kinase (CK; EC functions as a spatial and temporal energy buffer, dampening fluctuations in ATP levels as ATP supply and demand change. There are four CK isoforms in mammals, two cytosolic isoforms (muscle [M-CK] and brain [B-CK]), and two mitochondrial isoforms (ubiquitous [uMtCK] and sarcomeric [sMtCK]). Mammalian oxidative muscle couples expression of sMtCK with M-CK, creating an energy shuttle between mitochondria and myofibrils. We hypothesized that the expression pattern and activity of CK would differ between hearts of red- and white-blooded Antarctic notothenioid fishes due to their striking differences in cardiac ultrastructure. Hearts of white-blooded icefishes (family Channichthyidae) have significantly higher mitochondrial densities compared to red-blooded species, decreasing the diffusion distance for ATP between mitochondria and myofibrils and potentially minimizing the need for CK. The distribution of CK isoforms was evaluated using western blotting and maximal activity of CK was measured in mitochondrial and cytosolic fractions and tissue homogenates of heart ventricles of red- and white-blooded notothenioids. Transcript abundance of sMtCK and M-CK was also quantified. Overall, CK activity is similar between hearts of red- and white-blooded notothenioids but hearts of icefishes lack MtCK and have higher activities of M-CK in the cytosol compared to red-blooded fishes. The absence of MtCK may compromise cardiac function under stressful conditions when ATP supply becomes limiting.

      PubDate: 2014-09-02T02:29:30Z
  • The peptide hormone cholecystokinin modulates the tonus and compliance of
           the bulbus arteriosus and pre-branchial vessels of the rainbow trout
           (Oncorhynchus mykiss)
    • Abstract: Publication date: Available online 4 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Henrik Seth , Michael Axelsson , Albin Gräns
      The bulbus arteriosus is a compliant structure between the ventricle and ventral aorta of teleost fish. It serves as a “wind-kessel” that dampens pressure variations during the cardiac cycle allowing a continuous flow of blood into the gills. The bulbus arteriosus receives sympathetic innervation and is affected by several circulating substances, indicating neurohumoral control. We have previously shown that the peptide hormone, cholecystokinin (CCK), affects the hemodynamics of the cardiovascular system in rainbow trout (Oncorhynchus mykiss) by increasing flow pulse amplitude without affecting cardiac output. We hypothesized that this could be explained by an altered tonus or compliance/distensibility of the bulbus arteriosus. Our results show that there is a substantial effect of CCK on the bulbus arteriosus. Concentrations of CCK that altered the cardiac function of in situ perfused hearts also contracted the bulbus arteriosus in vitro. Pressure–volume curves revealed a change in both the tonus and the compliance/distensibility of this structure. Furthermore, the stimulatory (constricting) effect of CCK was also evident in the ventricle and vasculature leading to the gills, but absent in the atrium, efferent branchial arteries and dorsal aorta. In conclusion, CCK alters the mechanical properties of the ventricle, bulbus arteriosus, ventral aorta and afferent gill vasculature, thus maintaining adequate branchial and systemic blood flow and pressure when cardiorespiratory demands change, such as after feeding.

      PubDate: 2014-08-08T00:31:18Z
  • How do measurement duration and timing interact to influence estimation of
           basal physiological variables of a nocturnal rodent?
    • Abstract: Publication date: Available online 7 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): M.K. Connolly , C.E. Cooper
      Metabolic rate and evaporative water loss are two commonly measured physiological variables. It is therefore important, especially for comparative studies, that these variables (and others) are measured under standardised conditions, of which a resting state during the inactive phase is part of the accepted criteria. Here we show how measurement duration and timing affect these criteria and impact on the estimation of basal metabolic rate (oxygen consumption and carbon dioxide production) and standard evaporative water loss of a small nocturnal rodent. Oxygen consumption, carbon dioxide production and evaporative water loss all decreased over the duration of an experiment. Random assortment of hourly values indicated that this was an animal rather than a random effect for up to 11h. Experimental start time also had a significant effect on measurement of physiological variables. A longer time period was required to achieve minimal carbon dioxide consumption and evaporative water loss when experiments commenced earlier in the day, however experiments with earlier start times had a lower overall estimates of minimal oxygen consumption and carbon dioxide production. For this species, measurement duration of at least 8h, ideally commencing between before the inactive phase at 03:00h and 05:00h, is required to obtain minimal standard values for physiological variables. Up to 80% of recently published studies measuring basal metabolic rate and/or evaporative water loss of small nocturnal mammals may overestimate basal values due to insufficiently long measurement duration.

      PubDate: 2014-08-08T00:31:18Z
  • A critical evaluation of automated blood gas measurements in comparative
           respiratory physiology
    • Abstract: Publication date: Available online 1 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Christian Lind Malte , Sashia Lindhøj Jakobsen , Tobias Wang
      Precise measurements of blood gases and pH are of pivotal importance to respiratory physiology. However, the traditional electrodes that could be calibrated and maintained at the same temperature as the experimental animal are increasingly being replaced by new automated blood gas analyzers. These are typically designed for clinical use and automatically heat the blood sample to 37°C for measurements. While most blood gas analyzers allow for temperature corrections of the measurements, the underlying algorithms are based on temperature-effects for human blood, and any discrepancies in the temperature dependency between the blood sample from a given species and human samples will bias measurements. In this study we review the effects of temperature on blood gases and pH and evaluate the performance of an automated blood gas analyzer (GEM Premier 3500). Whole blood obtained from pythons and freshwater turtles was equilibrated in rotating Eschweiler tonometers to a variety of known PO2's and PCO2's in gas mixtures prepared by Wösthoff gas mixing pumps and blood samples were measured immediately on the GEM Premier 3500. The pH measurements were compared to measurements using a Radiometer BMS glass capillary pH electrode kept and calibrated at the experimental temperature. We show that while the blood gas analyzer provides reliable temperature-corrections for PCO2 and pH, PO2 measurements were substantially biased. This was in agreement with the theoretical considerations and emphasizes the need for critical calibrations/corrections when using automated blood gas analyzers.

      PubDate: 2014-08-04T00:01:24Z
  • Exploring the consequences of mitochondrial differences arising through
           hybridization of sunfish
    • Abstract: Publication date: Available online 26 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): K. Mathers , J. Cox , Y. Wang , C.D. Moyes
      Previous studies have shown evidence of genomic incompatibility and mitochondrial enzyme dysfunction in hybrids of bluegill (Lepomis macrochirus Rafinesque) and pumpkinseed (L. gibbosus Linnaeus) sunfish (Davies et al., 2013 Physiol. Biochem. Zool. 85, 321–331). We assessed if these differences in mitochondria had an impact on metabolic processes that depend on mitochondrial function, specifically hypoxia tolerance and recovery from burst exercise. Bluegill, pumpkinseed, and their hybrids showed no difference in the critical oxygen tension (Pcrit) and no differences in tissue metabolites measured after exposure to 10% O2 for 30min. In contrast, loss of equilibrium (LOE) measurements showed that hybrids had reduced hypoxia tolerance and lacked the size-dependence in hypoxia tolerance seen in the parental species. However, we found no evidence of systematic differences in metabolite levels in fish after LOE. Furthermore, there were abundant glycogen reserves at the point of loss of equilibrium. The three genotypes did not differ in metabolite status at rest, showed an equal disruption at exhaustion, and similar metabolic profiles throughout recovery. Thus, we found no evidence of a mitochondria dysfunction in hybrids, and mitochondrial differences and oxidative metabolism did not explain the variation in hypoxia tolerance seen in the hybrid and two parental species.

      PubDate: 2014-07-26T23:36:34Z
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