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  Subjects -> BIOLOGY (Total: 2541 journals)
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BIOCHEMISTRY (188 journals)                  1 2     

AAPS PharmSciTech     Hybrid Journal   (4 followers)
Acetic Acid Bacteria     Open Access   (1 follower)
ACS Chemical Biology     Full-text available via subscription   (171 followers)
ACS Chemical Neuroscience     Full-text available via subscription   (10 followers)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (8 followers)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (5 followers)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (6 followers)
Advances in Biological Chemistry     Open Access   (5 followers)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (5 followers)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (6 followers)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (8 followers)
African Journal of Biochemistry Research     Open Access  
African Journal of Chemical Education     Open Access  
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (3 followers)
American Journal of Biochemistry     Open Access   (5 followers)
American Journal of Biochemistry and Biotechnology     Open Access   (80 followers)
American Journal of Biochemistry and Molecular Biology     Open Access   (7 followers)
Amino Acids     Hybrid Journal   (7 followers)
Analytical Biochemistry     Hybrid Journal   (121 followers)
Annals of Clinical Biochemistry     Hybrid Journal   (1 follower)
Annual Review of Biochemistry     Full-text available via subscription   (25 followers)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (8 followers)
Applied Biochemistry and Biotechnology     Hybrid Journal   (17 followers)
Applied Biochemistry and Microbiology     Hybrid Journal   (6 followers)
Applied Organometallic Chemistry     Hybrid Journal   (3 followers)
Archives of Biochemistry and Biophysics     Hybrid Journal   (9 followers)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (1 follower)
Archives Of Physiology And Biochemistry     Hybrid Journal   (1 follower)
Asian Journal of Biochemistry     Open Access   (1 follower)
Bangladesh Journal of Medical Biochemistry     Open Access   (2 followers)
BBR : Biochemistry and Biotechnology Reports     Open Access   (2 followers)
Biochemical and Biophysical Research Communications     Hybrid Journal   (13 followers)
Biochemical and Molecular Medicine     Full-text available via subscription   (2 followers)
Biochemical Engineering Journal     Hybrid Journal   (8 followers)
Biochemical Genetics     Hybrid Journal   (1 follower)
Biochemical Journal     Full-text available via subscription   (14 followers)
Biochemical Pharmacology     Hybrid Journal   (5 followers)
Biochemical Society Transactions     Full-text available via subscription   (2 followers)
Biochemical Systematics and Ecology     Hybrid Journal   (2 followers)
Biochemistry     Full-text available via subscription   (122 followers)
Biochemistry (Moscow)     Hybrid Journal   (3 followers)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (4 followers)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (4 followers)
Biochemistry and Cell Biology     Full-text available via subscription   (8 followers)
Biochemistry and Molecular Biology Education     Hybrid Journal   (2 followers)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (1 follower)
Biochemistry Research International     Open Access   (3 followers)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (3 followers)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (16 followers)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (5 followers)
Biochimie     Hybrid Journal   (4 followers)
Bioconjugate Chemistry     Full-text available via subscription   (13 followers)
BioDrugs     Full-text available via subscription   (7 followers)
Bioelectrochemistry     Hybrid Journal   (3 followers)
Biofuels     Full-text available via subscription   (7 followers)
Biogeochemistry     Hybrid Journal   (5 followers)
BioInorganic Reaction Mechanisms     Full-text available via subscription   (1 follower)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (8 followers)
Biomedicines     Open Access  
BioMolecular Concepts     Full-text available via subscription   (2 followers)
Bioscience, Biotechnology, and Biochemistry     Open Access   (6 followers)
Biosimilars     Open Access   (1 follower)
Biotechnology and Applied Biochemistry     Hybrid Journal   (17 followers)
BMC Biochemistry     Open Access   (8 followers)
BMC Chemical Biology     Open Access   (4 followers)
Carbohydrate Polymers     Hybrid Journal   (8 followers)
Cell Biochemistry and Biophysics     Hybrid Journal   (5 followers)
Cell Biochemistry and Function     Hybrid Journal   (3 followers)
Cellular Physiology and Biochemistry     Open Access   (3 followers)
Central European Journal of Chemistry     Hybrid Journal   (5 followers)
ChemBioChem     Hybrid Journal   (2 followers)
Chemical Biology & Drug Design     Hybrid Journal   (23 followers)
Chemical Engineering Journal     Hybrid Journal   (16 followers)
Chemical Senses     Hybrid Journal   (1 follower)
Chemical Speciation and Bioavailability     Full-text available via subscription   (1 follower)
Chemico-Biological Interactions     Hybrid Journal   (2 followers)
Chemistry & Biodiversity     Hybrid Journal   (5 followers)
Chemistry & Biology     Full-text available via subscription   (16 followers)
Chemistry and Ecology     Hybrid Journal   (1 follower)
Clinical Biochemist Reviews     Full-text available via subscription   (1 follower)
Clinical Biochemistry     Hybrid Journal   (3 followers)
Clinical Chemistry and Laboratory Medicine     Full-text available via subscription   (4 followers)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (5 followers)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (2 followers)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (4 followers)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (3 followers)
Comprehensive Biochemistry     Full-text available via subscription   (1 follower)
Computational Biology and Chemistry     Hybrid Journal   (8 followers)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (2 followers)
Current Chemical Biology     Hybrid Journal   (1 follower)
Current Opinion in Chemical Biology     Hybrid Journal   (13 followers)
Current Opinion in Lipidology     Hybrid Journal   (2 followers)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (2 followers)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
FEBS Letters     Hybrid Journal   (24 followers)
FEBS Open Bio     Open Access   (1 follower)

        1 2     

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  [2556 journals]
  • Editorial Board
    • Abstract: Publication date: July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 173




      PubDate: 2014-04-15T16:22:13Z
       
  • Assessing the energetic costs and trade-offs of a PHA-induced inflammation
           in the subterranean rodent Ctenomys talarum: Immune response in growing
           tuco-tucos
    • Abstract: Publication date: Available online 12 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ana Paula Cutrera , Facundo Luna , Julieta L. Merlo , María Belén Baldo , Roxana R. Zenuto
      A traditional approach used to assess whether immune defense is costly is to explore the existence of trade-offs between immunity and other functions; however, quantitative studies of the energetic costs associated with the activation of the immune system are scarce. We assessed the magnitude of a PHA-triggered immune response and the associated energetic costs in 60-day old Ctenomys talarum. We expected that the magnitude of the macroscopic inflammatory response to PHA is lower in young tuco-tucos compared with that of adults, given the allocation of substantial energy to growth, and that the magnitude of the inflammation is lower in male pups compared to females, due to the higher investment in growth of the larger sex. Concomitantly, we expected that the pups challenged with PHA show an increase in oxygen consumption compared to control animals and that a positive association exists between magnitude of the PHA-induced inflammation and oxygen consumption. Contrary to what was expected, young tuco-tucos mounted a higher inflammatory response compared with adults and there were no differences in the magnitude of this response between sexes. The inflammatory response induced by a PHA injection did not represent a significant energetic cost for young tuco-tucos. There were no differences in oxygen consumption between PHA-injected and control animals, and tuco-tucos that mounted a higher inflammatory response to PHA did not show higher oxygen consumption. Energy expenditure, however, is not the only physiological cost involved in trade-offs between immune response and various functions of the organism, and other currencies are discussed.


      PubDate: 2014-04-15T16:22:13Z
       
  • Adenosinergic regulation of the cardiovascular system in the red-eared
           slider Trachemys scripta
    • Abstract: Publication date: Available online 12 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): William Joyce , Tobias Wang
      Few studies have investigated adenosinergic regulation of the cardiovascular system in reptiles. The haemodynamic effect of a bolus intra-arterial adenosine injection (2.5μMkg−1) was investigated in nine anaesthetised red-eared sliders (Trachemys scripta). Adenosine caused a transient bradycardia, which was accompanied by systemic vasodilatation as evidenced by an increase in systemic flow and a decrease in systemic pressure. Meanwhile, pulmonary flow fell significantly. Both the bradycardia and increase in systemic conductance were significantly attenuated by theophylline (4mgkg−1), demonstrating an involvement of P1 receptors. These results suggest that adenosine is likely to play a significant role in reptile cardiovascular physiology. In turtles specifically, adenosinergic regulation may be particularly relevant during periods of apnoea.


      PubDate: 2014-04-15T16:22:13Z
       
  • Corrigendum to “Variability in swimming performance and underlying
           physiology in rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo
           trutta)” [Comp. Biochem. Physiol., A 163 (2012) 350–356]
    • Abstract: Publication date: Available online 8 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Allison L. Ralph , Barbara I. Berli , Patricia Burkhardt-Holm , Keith B. Tierney



      PubDate: 2014-04-10T16:15:17Z
       
  • Physiological indices of stress in wild and captive garter snakes:
           Correlations, repeatability, and ecological variation
    • Abstract: Publication date: Available online 5 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Amanda M. Sparkman , Anne M. Bronikowski , Shelby Williams , Shikha Parsai , Whitney Manhart , Maria G. Palacios
      Glucocorticoids and leukocyte ratios have become the most widespread variables employed to test hypotheses regarding physiological stress in wild and captive vertebrates. Little is known, however, regarding how these two indices of stress covary in response to stressors, their repeatability within individuals, and differences in response time upon capture. Furthermore, few studies compare stress indices between captive and wild populations, to assess potential alteration of stress physiology in captivity. To address these issues, we examined corticosterone (CORT) and heterophil to lymphocyte (H:L) ratios in two ecotypes of the garter snake Thamnophis elegans. We found that CORT and H:L ratios were not correlated within individuals, and both variables showed little or no repeatability over a period of months. CORT levels, but not H:L ratios, were higher for individuals sampled after ten min from the time of capture. However, both variables showed similar patterns of ecotypic variation, and both increased over time in gravid females maintained in captivity for four months. We suggest that CORT and H:L ratios are both useful, but disparate indices of stress in this species, and may show complex relationships to each other and to ecological and anthropogenic variables.


      PubDate: 2014-04-10T16:15:17Z
       
  • Phenotypic flexibility in passerine birds: Seasonal variation in fuel
           storage, mobilization and transport
    • Abstract: Publication date: Available online 3 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Eric T. Liknes , Christopher G. Guglielmo , David L. Swanson
      Winter acclimatization in small birds living in cold climates produces a winter phenotype characterized by upregulation of metabolic rates to meet enhanced thermoregulatory demands. We measured several key aspects of fuel storage, mobilization and transport in summer and winter to determine whether black-capped chickadees (Poecile atricapillus), white-breasted nuthatches (Sitta carolinensis), and house sparrows (Passer domesticus) seasonally modulate these attributes to meet enhanced winter thermoregulatory demands. In addition, we exposed birds to thermoneutral (control) and severe cold exposure treatments to determine whether acute cold exposure influenced fuel storage, mobilization or transport. Carcass lipid mass and pectoralis intramuscular lipid did not vary significantly between seasons or temperature treatments for any of the study species. Muscle glycogen varied significantly seasonally only for chickadee supracoracoideus and leg muscles, and did not vary among warm or cold treatments for any species. Pectoralis fatty acid binding protein (FABPc) was significantly elevated in winter for chickadees and nuthatches, but not for sparrows. Plasma metabolites showed little consistent variation in response to season or acute cold exposure. Thus, fuel storage and mobilization do not appear to be major targets of adjustment associated with seasonal metabolic flexibility in these species, but modulation of intracellular lipid transport by FABPc may be an important contributor to seasonal phenotypes in some species of small birds.


      PubDate: 2014-04-05T11:17:02Z
       
  • Influence of domestication process on immune response to repeated emersion
           stressors in Eurasian perch (Perca fluviatilis, L.)
    • Abstract: Publication date: Available online 25 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): J. Douxfils , S. Lambert , C. Mathieu , S. Milla , S.N.M. Mandiki , E. Henrotte , N. Wang , M. Dieu , M. Raes , C. Rougeot , P. Kestemont
      Domestication might be a possible way to reduce the physiological response to long-term stressors and deleterious effects on immunity. The present study aimed to evaluate the chronic immune response induced by repeated emersions and the possible impact of domestication by comparing farmed Eurasian perch with short (F1) and long (F4) captive-life history. In a first experiment, fish were exposed to a single emersion and physiological stress response was measured in the short term to characterize fish sensitivity to the tested stressor. Serum cortisol and glucose elevated within 6h post-stress and splenosomatic index (SSI) decreased within 48h, indicating that the species was affected by emersion stressor. In a second experiment, F1 and F4 generations were submitted to repeated water emersions (3 times/week during 44days). On day 9, 18 and 44, samplings were performed 48h post-stressor to highlight any sustained disruption of immune system. Serum cortisol, glucose, SSI and lysozyme activity were evaluated and serum proteome was analyzed using 2D-DIGE. Any of the tested variables were affected by repeated emersions and proteomic analysis only revealed that alpha-2 macroglobulins (a2M) were up-regulated in the serum of stressed individuals. Domestication also resulted in up-regulation of five a2M isoforms and down-regulation of complement C3 and Ig light chain proteins, independently of any stressor exposure. In conclusion, the results suggested that repeated emersions are not severe stressors for Eurasian perch, probably explaining why domestication had no influence on fish responses. Changes associated with domestication are highly complex and certainly need further investigations.


      PubDate: 2014-03-26T07:40:29Z
       
  • Carotenoid-based coloration in cichlid fishes
    • Abstract: Publication date: Available online 22 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kristina M. Sefc , Alexandria C. Brown , Ethan D. Clotfelter
      Animal colors play important roles in communication, ecological interactions and speciation. Carotenoid pigments are responsible for many yellow, orange and red hues in animals. Whereas extensive knowledge on the proximate mechanisms underlying carotenoid coloration in birds has led to testable hypotheses on avian color evolution and signaling, much less is known about the expression of carotenoid coloration in fishes. Here, we promote cichlid fishes (Perciformes: Cichlidae) as a system in which to study the physiological and evolutionary significance of carotenoids. Cichlids include some of the best examples of adaptive radiation and color pattern diversification in vertebrates. In this paper, we examine fitness correlates of carotenoid pigmentation in cichlids and review hypotheses regarding the signal content of carotenoid-based ornaments. Carotenoid-based coloration is influenced by diet and body condition and is positively related to mating success and social dominance. Gaps in our knowledge are discussed in the last part of this review, particularly in the understanding of carotenoid metabolism pathways and the genetics of carotenoid coloration. We suggest that carotenoid metabolism and transport are important proximate mechanisms responsible for individual and population-differences in cichlid coloration that may ultimately contribute to diversification and speciation.


      PubDate: 2014-03-26T07:40:29Z
       
  • Thermoregulatory development and behavior of Ctenomys talarum pups during
           brief repeated postnatal isolation
    • Abstract: Publication date: Available online 22 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): María Belén Baldo , Facundo Luna , Cristian E. Schleich , C. Daniel Antenucci
      In altricial mammals, the role of the mother and siblings throughout pup´s early ontogeny are critical to determine “normal” development in neonates. It has been reported that variations in parental investment during pups´ development affect thermoregulatory capacity, growth patterns, brain development and behavior during lifetime, such as spatial learning and memory in adults. Ctenomys talarum (tuco-tucos) is a solitary subterranean rodent, who inhabits complex burrows and exhibits developed spatial orientation abilities. Tuco-tuco´s pups display an altricial development, spending more than 80% of the time in contact with the mother. Throughout weaning period, pups display active exploratory behavior and improvements in their spatial capabilities. Then, we determined the effect of repeated brief postnatal isolations on the acquisition of physiological thermoregulation and the development of spatial learning capabilities in tuco-tuco’s pups. As occurs in wild animals, daily brief isolations (30min) did not affect the acquisition of adult´s body temperature nor resting metabolic rate´s development pattern. Moreover, behavioral response and adult spatial abilities of isolated pups were similar to the observed in not separated ones. Then, during periods of mother´s absence, minor physiological and behavioral adjustments, such as shivering and postural changes, are required to keep C. talarum pups within allostasis.


      PubDate: 2014-03-26T07:40:29Z
       
  • A comparative study of reproductive and metabolic responses to
           administration of exogenous melatonin and aldosterone in xeric and mesic
           spiny mice populations
    • Abstract: Publication date: Available online 24 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Elena Bukovetzky , Abraham Haim
      A comparative study of reproduction revealed differences between desert-adapted Acomys russatus and Mediterranean Acomys cahirinus populations with respect to the environmental cues used for reproductive activity. Long day (LD) conditions, were noted as initial reproductive cue for both populations. This research is a follow up comparative endocrine and metabolic study in regards to reproduction where LD-acclimated mice mice were treated with, exogenous aldosterone (ALDO) and melatonin (MLT). Only the reproductive system of A. russatus females was significantly affected by both hormones. In A. cahirinus females, MLT decreased leptin levels, while in A. russatus, a treatment with both hormones increased leptin levels. In A. russatus males, MLT affect both, reproductive and metabolic functions. However, in A. cahirinus males, ALDO and MLT treatments caused an increase in leptin levels, and decrease in Free Fatty Acid (FFA) levels, respectively. Correlations between leptin and FFA in general were affected by both MLT and ALDO treatments in A. russatus males and A. cahirinus females. Our results support the general idea, that although the reproductive system of A. russatus responded to an osmotic stress, in our case expressed by ALDO treatment, which can be considered as an ultimate signal, where, photoperiod changes are an initial signal.


      PubDate: 2014-03-26T07:40:29Z
       
  • Editorial Board
    • Abstract: Publication date: June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 172




      PubDate: 2014-03-26T07:40:29Z
       
  • Thermal stress alters expression of genes involved in one carbon and DNA
           methylation pathways in Atlantic cod embryos
    • Abstract: Publication date: Available online 16 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kaja H. Skjærven , Kristin Hamre , Samuel Penglase , Roderick Nigel Finn , Pål A. Olsvik
      One-carbon (1-C) metabolism is essential for normal embryonic development through its regulation of DNA methylation and cell proliferation. With consideration to the potential future anthropogenic oceanic warming, we studied effects of both acute and continuous thermal stress (10°C) during Atlantic cod embryo development on the expression levels of genes associated with the 1-C metabolism, including DNA methyltransferases. We conducted a phylogenetic analysis of vertebrate DNA methyltransferases to determine the number and similarity of DNMT found in Atlantic cod. This analysis revealed that Atlantic cod have one maintenance dnmt (dnmt1) and five de novo DNMTs (dnmt4, dnmt3, dnmt3b, dnmt3aa, dnmt3ab). Stage specific changes in expression levels occurred for all genes analysed. The effect of acute thermal stress was evaluated during early development. Compared to controls these experiments showed significant alterations in expression levels of several genes, that in some instances were reversed at later stages of development. A significant effect of continuous thermal stress was found in gastrula embryos where lower mRNA expression levels of 1-C metabolism, de novo DNMT’s and cell proliferation genes were detected. One exception was the maintenance DNMT, which was only sensitive to acute and not continuous thermal stress. DNA methylation status indicated that blastula embryos were hypomethylated compared to spermatozoa and late gastrula stages. In post-gastrula stage, however, continuous thermal stress resulted in a higher degree of DNA methylation compared to controls. These data reveal that the regulation of epigenetically important transcripts in the 1-C metabolism of Atlantic cod embryos is sensitive to thermal stress.


      PubDate: 2014-03-21T06:53:21Z
       
  • Editorial Board
    • Abstract: Publication date: May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 171




      PubDate: 2014-03-16T07:30:56Z
       
  • Editorial Board
    • Abstract: Publication date: April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 170




      PubDate: 2014-03-11T07:31:57Z
       
  • Thermal tolerance in juvenile King George whiting (Silliginodes punctata)
           reduces as fish age and this reduction coincides with migration to deeper
           colder water
    • Abstract: Publication date: Available online 5 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): C.A. Meakin , J.G. Qin , L.D. Pogson , C.A. Abbott
      Heat shock proteins (HSP) are sensitive and readily produced under thermal stress in many fish species and thus serve as a useful stress bio-indicator. Two experiments were conducted to test the hypothesis that King George whiting Sillaginodes punctata (KGW) approaching sexual maturity exhibit a decrease in HSP production and that exposure to high temperatures provokes HSP production in juvenile whiting. Both adult and juvenile whiting expressed significant increases in HSP69 in response to temperature shocks of 24, 26, 28 and 30 ºC. Juvenile whiting had significantly higher HSP69 than adults and expressed more HSP69 at 24 and 26 ºC. No mortalities were observed in juvenile fish at 30 ºC while 50% of adults suffered mortality at 30 ºC. Following exposure of juveniles to 24, 26 and 28 ºC, HSP69 was measured at 24, 96 and 168 h. HSP69 peaked at 96 h and returned to the 24 h level after 168 h exposure. This study indicates that juveniles can cope with high temperatures better than adults, which offers a partial explanation to fish movement patterns in nature where younger fish inhabit near shore waters and then migrate to deep water towards maturation. Further, this work implies that KGW growth and recruitment can be affected by increasing temperatures due to global warming.


      PubDate: 2014-03-11T07:31:57Z
       
  • Oxidative stress decreases with elevation in the lizard Psammodromus
           algirus
    • Abstract: Publication date: Available online 3 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Senda Reguera , Francisco J. Zamora-Camacho , Cristina E. Trenzado , Ana Sanz , Gregorio Moreno-Rueda
      Oxidative stress is considered one of the main ecological and evolutionary forces. Several environmental stressors vary geographically and thus organisms inhabiting different sites face different oxidant environments. Nevertheless, there is scarce information about how oxidative damage and antioxidant defences vary geographically in animals. Here we study how oxidative stress varies from lowlands (300–700m asl) to highlands (2200–2500m asl) in the lizard Psammodromus algirus. To accomplish this, antioxidant enzymatic activity (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase) and lipid peroxidation were assayed in tissue samples from the lizards’ tail. Lipid peroxidation was higher in individuals from lowlands than from highlands, indicating higher oxidative stress in lowland lizards. These results suggest that environmental conditions are less oxidant at high elevations with respect to low ones. Therefore, our study shows that oxidative stress varies geographically, which should have important consequences for our understanding of geographic variation in physiology and life-history of organisms.


      PubDate: 2014-03-06T07:37:30Z
       
  • Species- and sex-specific responses and recovery of wild, mature pacific
           salmon to an exhaustive exercise and air exposure stressor
    • Abstract: Publication date: Available online 4 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Michael R. Donaldson , Scott G. Hinch , Ken M. Jeffries , David A. Patterson , Steven J. Cooke , Anthony P. Farrell , Kristina M. Miller
      Despite the common mechanisms that underlie vertebrate responses to exhaustive exercise stress, the magnitude and the timecourse of recovery can be context-specific. Here, we examine how wild, adult male and female pink (Oncorhynchus gorbuscha) and sockeye (O. nerka) salmon respond to and recover from an exhaustive exercise and air exposure stressor, designed to simulate fisheries capture and handling. We follow gill tissue gene expression for genes active in cellular stress, cell maintenance, and apoptosis as well as plasma osmoregulatory, stress, and reproductive indices. The stressor initiated a major stress response as indicated by increased normalized expression of two stress-responsive genes, transcription factor JUNB and cytochrome C (pink salmon only). The stressor resulted in increased plasma ions cortisol, lactate, and depressed estradiol (sockeye salmon only). Gene expression and plasma variables showed a general recovery by 24h post-stressor. Species- and sex-specific patterns were observed in stress response and recovery, with pink salmon mounting a higher magnitude stress response for plasma variables and sockeye salmon exhibiting a higher and more variable gene expression profile. These results highlight species- and sex-specific responses of migrating Pacific salmon to simulated fisheries encounters, which contribute new knowledge towards understanding the consequences of fisheries capture-and-release.


      PubDate: 2014-03-06T07:37:30Z
       
  • Chickens from lines artificially selected for juvenile low and high body
           weight differ in glucose homeostasis and pancreas physiology
    • Abstract: Publication date: Available online 5 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): L.H. Sumners , W. Zhang , X. Zhao , C.F. Honaker , S. Zhang , M.A. Cline , P.B. Siegel , E.R. Gilbert
      Artificial selection of White Plymouth Rock chickens for juvenile (d 56) body weight resulted in two divergent genetic lines; hypophagic low weight (LWS) chickens and hyperphagic obese high weight (HWS) chickens, with the latter more than 10-fold heavier than the former at selection age. A study was designed to investigate glucose regulation and pancreas physiology in selection age LWS and HWS chickens. Oral glucose tolerance and insulin sensitivity tests revealed differences in threshold sensitivity to insulin and glucose clearance rate between the lines. Results from real-time PCR showed greater pancreatic mRNA expression of four glucose regulatory genes (preproinsulin, PPI; preproglucagon, PPG; glucose transporter 2, GLUT2; and pancreatic duodenal homeobox 1, Pdx1) in LWS, than HWS chickens. Histological analysis of pancreas revealed that HWS chickens have larger pancreatic islets, less pancreatic islet mass, and more pancreatic inflammation than LWS chickens, all of which presumably contribute to impaired glucose metabolism.


      PubDate: 2014-03-06T07:37:30Z
       
  • Relating diving behavior and antioxidant status: Insights from oxidative
           stress biomarkers in the blood of two distinct divers, Mirounga leonina
           and Arctocephalus australis
    • Abstract: Publication date: Available online 5 March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): B.P.H. Righetti , P.C. Simões-Lopes , M.M. Uhart , D. Wilhelm Filho
      Pinnipeds rely upon diving to perform essential activities, including foraging. As pulmonated animals, oxygen privation experienced during submergence represents a considerable challenge both physiologically and biochemically. Routine exposure to hypoxia and the rapid transitions between ischemia/reperfusion of tissues leads to extremely high reactive oxygen species (ROS) production, which must be opposed by antioxidant defenses to avoid oxidative stress. The diving behaviors and capabilities of pinnipeds are very diverse, resulting in distinct metabolic responses among species. To assess whether these characteristics reflect the antioxidant status of two marine diving mammals with distinct diving capacities, oxidative stress biomarkers were measured in the blood of Arctocephalus australis (n=11) and Mirounga leonina (n=12). All of the biomarkers analyzed in M. leonina were significantly higher than those of A. australis, suggesting that higher antioxidant content is needed to counteract the high ROS production associated with the long submergence times (24.3 ± 5.6 min) of this species, which are nearly ten times greater than those of A. australis (2.8±0.5 min). Thus, the constitutive antioxidant defenses of both species are of distinct magnitudes due to their inherent diving capacity.


      PubDate: 2014-03-06T07:37:30Z
       
  • Yolk contributes steroid to the multidimensional endocrine environment of
           embryos of Niveoscincus metallicus, a viviparous skink with a moderately
           complex placenta
    • Abstract: Publication date: Available online 21 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Laura M. Parsley , Erik Wapstra , Susan M. Jones
      Maternally-derived testosterone (T) and 17-β-oestradiol (E2) provide epigenetic mechanisms by which mothers can actively influence offspring phenotype. In amniotes, maternal steroids may be derived from yolk or transferred across the placenta according to parity mode. Viviparous reptiles utilise both a yolk and a placenta to support their developing embryos, but it has not yet been confirmed whether yolk is a source of maternal T and E2 in such species. We investigated this question using the viviparous lizard Niveoscincus metallicus as our model species. We measured T and E2 in the yolks during vitellogenesis, immediately post ovulation and at progressive stages of gestation. Our results confirm that yolk is a substantial source of T and E2 in N. metallicus. Contrary to the pattern seen in many oviparous species, we did not observe a marked decline in yolk concentrations of either T or E2 after the initiation of sexual differentiation in the embryos. Rather, we found no statistically significant decline in yolk concentrations of both T and E2 post ovulation. In viviparous reptiles that utilise both yolk and placenta to nourish their embryos, yolk likely plays an important role in these dynamics but that role is not yet clear. Further research is warranted to understand the importance of yolk steroids in the endocrine environment of the developing viviparous reptile.


      PubDate: 2014-02-24T12:15:40Z
       
  • Melatonin-mediated effects on killifish reproductive axis
    • Abstract: Publication date: Available online 15 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Francesco Lombardo , Giorgia Gioacchini , Adele Fabbrocini , Michela Candelma , Raffaele D'Adamo , Elisabetta Giorgini , Oliana Carnevali
      The aim of this study was to investigate the melatonin-mediated effects upon the neuroendocrine axis of the brackish killifish (Fundulus heteroclitus), a suitable experimental model to study reproductive events. The ability of melatonin to enhance reproductive capacity (fecundity, embryo survival and hatching rate) inducing the transcriptional activity of Gonadotropin Releasing Hormone (gnrh), Luteinizing Hormone Receptor (lhr) and melatonin receptor (mtnr) was investigated in adult females. Moreover, the melatonin-mediated enhancement of killifish sperm motility and velocity was found consistent with higher fecundity of melatonin-exposed fishes. As a further extent, Fourier Transform Infrared (FT-IR) microspectroscopy evidenced a reduction of lipids unsaturation level on isolated spermatozoa from treated males. Moreover, the reduction of mtnr gene expression during embryo development and lower biometric parameters documented in larvae from melatonin-exposed parents suggest that melatonin acts as an hormonal mediator able to transfer the environmental signal to oocytes and then to embryos as inheritance of adaptive environmental changes. These results support the positive role of melatonin on killifish reproduction and its role as maternal factor on embryo and larval development.


      PubDate: 2014-02-19T07:21:32Z
       
  • Damage caused during hypoxia and reoxygenation in the locomotor muscle of
           the crab Neohelice granulata (Decapoda: Varunidae)
    • Abstract: Publication date: Available online 15 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Márcio Alberto Geihs , Marcelo Alves Vargas , Luiz Eduardo Maia Nery
      The aim of this work was to determine whether different durations of severe hypoxia (0.5 mgO2.L-1) followed by reoxygenation cause damage to the locomotor muscle of the crab Neohelice granulata. We evaluated reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial membrane potential, and aerobic fiber area of the locomotor muscle after different periods of hypoxia (1, 4, or 10h) followed by 30 or 120min of reoxygenation. Additionally, changes in cell volume, mitochondrial dysfunction, and infiltration of hemocytes were evaluated after hypoxia and a subsequent 2, 24, or 48h of reoxygenation. After hypoxia, neither ROS nor LPO increased. However, mitochondrial membrane potential and aerobic fiber area decreased in a time-dependent manner. After reoxygenation, the ROS and LPO levels increased and mitochondrial membrane potential decreased, but these quickly recovered in crabs exposed to 4h of hypoxia. On the other hand, alterations of mitochondria resulted in morphological changes in aerobic fibers, which required more time to recover during reoxygenation after 10h of hypoxia. The locomotor muscles of the crab N. granulata suffer damage after hypoxia and reoxygenation. The intensity of this damage is dependent on the duration of hypoxia. In all experimental situations analyzed, the locomotor muscle of this crab was capable of recovery.


      PubDate: 2014-02-19T07:21:32Z
       
  • Effect of hypoxia on specific dynamic action and postprandial
           cardiovascular physiology in rainbow trout (Oncorhynchus mykiss)
    • Abstract: Publication date: Available online 15 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Erika J. Eliason , Anthony P. Farrell
      Fish routinely encounter hypoxic environments, which may have detrimental effects on digestion and performance. The present study measured oxygen consumption (MO2), gastrointestinal blood flow (GBF), cardiac output (V b) and heart rate (f H) in rainbow trout Oncorhynchus mykiss at 10–11.5°C while exposed to a 1.5h step-wise hypoxia treatment (80, 60 and 40% saturation=16.7, 12.6, 8.4 kPa, respectively), which began 4h after being fed 1% of their body mass. GBF and f H significantly decreased by 41 and 25-29%, respectively, at the most severe hypoxia step (40% saturation), while MO2 and V b were maintained throughout the entire hypoxia exposure. Thus, GBF and f H were more sensitive to hypoxia than MO2 or V b in digesting rainbow trout. Subsequent to the hypoxic exposure, the fish were returned to normoxia and monitored for a total of 50h after feeding. While the magnitude of SDA was unaffected, peak postprandial MO2 was reduced by 17% and the duration of specific dynamic action (SDA) was prolonged by 6h in hypoxia-treated fish when compared to control fish. In conclusion, digestive performance was compromised both during and after the hypoxic exposure, which could lead to negative effects on growth.


      PubDate: 2014-02-19T07:21:32Z
       
  • Gill tissue lipids of salmon (Salmo salar L.) presmolts and smolts from
           anadromous and landlocked populations
    • Abstract: Publication date: Available online 16 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Y. Itokazu , R. Käkelä , J. Piironen , X.L. Guan , P. Kiiskinen , M. Vornanen
      Composition of membrane lipids from the gills of juvenile Atlantic salmon (Salmo salar) in presmolt and smolt phases of development were compared among anadromous and non-anadromous populations. Three stocks migrating from spawning rivers to either lake (landlocked stock), brackish water or full strength sea water were grown under common garden conditions, and gill lipids and their acyl and alkenyl chains were examined in February (presmolts) and at the end of May (smolts) by mass spectrometry and gas–liquid chromatography. The most remarkable changes upon transition from the presmolt phase to the smolt phase were: (i) increase in the cholesterol/phospholipid ratio, (ii) decrease in the abundance of phosphatidylinositol (PI) content, (iii) increase in the amount of sulphatides, (iv) increase in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) species with two highly unsaturated acyl chains, and finally (v) convergence of interstock differences in PC and PE species composition towards a similar lipid composition. Increases in the gill membrane content of cholesterol and sulphatides are discussed as pre-adaptation of salmon gills for salt-secretion, which may occur by increases in membrane microdomains (rafts) harboring ion channels and pumps. The decreases of PI were likely related to adjusting the gill membrane permeability to ions by diminishing prostanoid production. Similarity of those changes among three salmon stocks and the convergence of initially (presmolt phase) different PC and PE species profiles between the stocks towards similar lipid composition suggests that smoltification process of the gill epithelium is largely similar in anadromous and landlocked populations.


      PubDate: 2014-02-19T07:21:32Z
       
  • Esophageal desalination is mediated by Na+, H+ exchanger-2 in the gulf
           toadfish (Opsanus beta)
    • Abstract: Publication date: Available online 16 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Andrew J. Esbaugh , Martin Grosell
      Esophageal desalination is a crucial step in the gastrointestinal water absorption pathway, as this pre-intestinal processing establishes the osmotic conditions necessary for water absorption. Previous work has shown that esophageal Na+ absorption is amiloride sensitive; however, it is as yet unclear if Na+, H+ exchangers (NHE) or Na+ channels (ENaC) are responsible. The purpose of the current study was therefore to investigate the roles that NHE isoforms may play in this process in a marine teleosts, the gulf toadfish (Opsanus beta), as well as what role NHE isoforms may play in the downstream intestinal Na+ transport. A combination of symmetrical current clamp and asymmetrical voltage clamp experiments showed the esophagus to contain both an ion absorptive current (Isc =0.83±0.68) and serosal side negative transepithelial potential (TEP=−4.9±0.6). 22Na uptake (J Na m→s) was inhibited by 0.5mM EIPA, with no effect of 0.1mM amiloride, 1mM furosemide or 1mM thiazide. A Cl- free saline reduced J Na m→s by 40% while also reducing conductance and reversing TEP. These results suggest that both transcellular and paracellular components contribute to esophageal Na+ transport, with transcellular transport mediated by NHE. The NHE1, NHE2 and NHE3 genes were amplified and tissue distribution analysis by real-time PCR showed high NHE2 expression levels in the esophagus and stomach. Little NHE3 expression was observed throughout the gastrointestinal tract, and NHE2 expression was absent from the intestine. Hypersalinity (60ppt) had no effect on the expression profile of NHE2, slc4a2, scl26a6, CAc or V-type ATPase (β-subunit), suggesting that esophageal desalination is less flexible in response to osmotic stress than the intestine.


      PubDate: 2014-02-19T07:21:32Z
       
  • Tolerance of Venerupis philippinarum to salinity: Osmotic and metabolic
           aspects
    • Abstract: Publication date: Available online 17 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Vanessa Carregosa , Etelvina Figueira , Ana M. Gil , Sara Pereira , Joana Pinto , Amadeu M.V.M. Soares , Rosa Freitas
      In the last few decades, attention has been focused on the impacts of contamination in marine benthic populations, while the responses of aquatic organisms to natural alterations, namely changes in salinity, have received little attention. In fact, salinity is one of the dominant environmental factors affecting marine bivalves. The ebb and flood of the tide, combined with fresh water inputs from rivers or heavy rainy events, and with extreme dry and hot seasons, can dramatically alter water salinity. Therefore, the salinity of a certain environment can restrict the spatial distribution of a given population, which is especially important when assessing the spread of an invasive species into a new environment. In the present study, the main objective was to understand how clam Venerupis philippinarum copes with salinity changes and, hence biochemical and metabolomic alterations, taking place in individuals submitted to a wide range of salinities were investigated. The results showed that V. philippinarum presented high mortality at lower salinities (0 and 7g/L) but tolerated high salinities (35 and 42g/L). The quantification of ionic content revealed that, clams had the capacity to maintain ionic homeostasis along the salinity gradient, mainly changing the concentration of Na, but also with the influence of Mg and Ca. The results showed a decrease in protein content at lower salinities (0 to 21g/L). Glycogen and glucose increased with increasing salinity gradient. 1H Nuclear Magnetic Resonance (NMR) spectra of clams aqueous extracts revealed different metabolite profiles at 7, 28 and 42g/L salinities, thus enabling metabolite changes to be measured in relation to salinity.


      PubDate: 2014-02-19T07:21:32Z
       
  • Identification of ecdysteroid signaling late-response genes from different
           tissues of the Pacific white shrimp, Litopenaeus vannamei
    • Abstract: Publication date: Available online 17 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Zhaoying Qian , Shulin He , Tao Liu , Yongjie Liu , Fujun Hou , Qiao Liu , Xianzong Wang , Xiao Mi , Ping Wang , Xiaolin Liu
      Ecdysteroids initiate signaling along multiple pathways that regulate various aspects of development, maturation, and reproduction in arthropods. This study was carried out to seek the late target genes of ecdysteroid signaling from different tissues of the Pacific white shrimp, Litopenaeus vannamei. In the present study, eight isoforms of ecdysteroid receptor (EcR), two isoforms of retinoic acid X receptor (RXR), and one homolog of E75 were characterized from L. vannamei. The overall protein sequences and specific functional sites of EcR, RXR and E75 among crustacean species were found highly conserved. Tissue-specific, development stage-specific, and molt stage-specific expression patterns of LvEcR, LvRXR, and LvE75 were detected by qPCR. Double stranded RNA (dsRNA)-mediated RNA interference (RNAi) of any one of the three genes LvEcR, LvRXR and LvE75 caused specific expression changes of the other two, and resulted in corresponding expression changes of two molting related genes Cathepsin-L (LvCHSL) and Hemocyanin (LvHCyn) in the hepatopancreas, two chitin metabolism related genes chitin synthase (LvChS) and chitinase isoenzyme (LvChi2) in the epidermis, and two muscle growth related genes LvActin and myosin heavy chain (LvMHC) in the muscle. In correspondence, after in vivo injections of 20 hydroxyecdysone, specific expression changes of LvEcR, LvRXR, LvE75, LvCHSL and LvHCyn in the hepatopancreas, LvEcR, LvRXR, LvE75, LvChS and LvChi2 in the epidermis, and LvEcR, LvRXR, LvE75, LvActin and LvMHC in the muscle were also observed, respectively. Results in our study indicate multiple functions of ecdysteroids signaling in L. vannamei and the function may be time- and space- specific; ecdysteroids may act through different pathways via its functional receptor heterodimer EcR-RXR and the early responsive gene E75 to perform specific regulation roles on the target genes in different shrimp tissues; LvCHSL and LvHCyn in the hepatopancreas, LvChS and LvChi2 in the epidermis, and LvActin and LvMHC in the muscle are potential targets for ecdysteroids control. This is the first report on nuclear receptors in the economically important shrimp L. vannamei.


      PubDate: 2014-02-19T07:21:32Z
       
  • Cellular metabolic rates in cultured primary dermal fibroblasts and
           myoblast cells from fast-growing and control Coturnix quail.
    • Abstract: Publication date: Available online 14 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ana Gabriela Jimenez , Clara Cooper-Mullin , Nicholas B. Anthony , Joseph B. Williams
      Fibroblast cells have been extensively used in research, including in medicine, physiology, physiological-ecology, and conservation biology. However, whether the physiology of fibroblasts reflects the physiology of other cell types in the same animal is unknown. Dermal fibroblasts are responsible for generating connective tissue and involved in wound healing, but generally, this cell type is thought to be metabolically inactive until it is required at the site of tissue damage. Thus, one might question whether fibroblasts are a representative model system to portray the metabolic profile of the whole organism, as compared with cells isolated from other tissues, like muscle, brain or kidneys. To explore whether fibroblasts have the same metabolic profile as do myoblast cells, we cultured cells from day-old chicks of quail (Coturnix coturnix japonica) selected for fast-growth or normal growth (our control group). Our results suggest that isolated primary fibroblasts and myoblast cells had higher rates of glycolysis, oxygen consumption and more mitochondria in the fast-growing line than in the control line. Our findings lend support for the idea that fibroblasts are a representative cell system to characterize the whole organism metabolic signature at the cellular-level. These data are striking, however, because fibroblasts had higher rates of metabolism for every parameter measured than myoblast cells isolated from the same individuals.


      PubDate: 2014-02-14T22:21:30Z
       
  • Purine nucleoside phosphorylase and xanthine oxidase activities in
           erythrocytes and plasma from marine, semiaquatic and terrestrial mammals
    • Abstract: Publication date: Available online 13 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Roberto I. López-Cruz , Myrna Barjau Pérez-Milicua , Daniel E. Crocker , Ramón Gaxiola-Robles , Jaime Bernal , Alejandro de la Rosa , José P. Vázquez-Medina , Tania Zenteno-Savín
      Purine nucleoside phosphorylase (PNP) and xanthine oxidase (XO) are key enzymes involved in the purine salvage pathway. PNP metabolizes purine bases to synthetize purine nucleotides whereas XO catalyzes the oxidation of purines to uric acid. In humans, PNP activity is reported to be high in erythrocytes and XO activity to be low in plasma; however, XO activity increases after ischemic events. XO activity in plasma of northern elephant seals has been reported during prolonged fasting and rest and voluntary associated apneas. The objective of this study was to analyze circulating PNP and XO activities in marine mammals adapted to tolerate repeated cycles of ischemia/reperfusion associated with diving (bottlenose dolphin, northern elephant seal) in comparison with semiaquatic (river otter) and terrestrial mammals (human, pig). PNP activities in plasma and erythrocytes, as well as XO activity in plasma, from all species were quantified by spectrophotometry. No clear relationship in circulating PNP or XO activity could be established between marine, semiaquatic and terrestrial mammals. Erythrocytes from bottlenose dolphins and humans are highly permeable to nucleosides and glucose, intraerythrocyte PNP activity may be related to a release of purine nucleotides from the liver. High-energy costs will probably mean a higher ATP degradation rate in river otters, as compared to northern elephant seals or dolphins. Lower erythrocyte PNP activity and elevated plasma XO activity in northern elephant seal could be associated with fasting and/or sleep- and dive-associated apneas.


      PubDate: 2014-02-14T22:21:30Z
       
  • Purinoceptors exert negative inotropic effects on the heart in all major
           groups of reptiles
    • Abstract: Publication date: Available online 9 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): William Joyce , Hans Gesser , Tobias Wang
      The few and fragmentary studies on purinergic regulation of the reptile heart have reached equivocal conclusions. Indeed, unlike fish, amphibians, and mammals, it has been suggested the turtle heart lacks purinoceptors. Here, we study the effect of adenosine and ATP on isolated heart strips from three species of reptiles: the red-eared slider (Trachemys scripta), the ball python (Python regius) and the spectacled caiman (Caiman crocodilus). Both adenosine and ATP markedly decreased contractility in atria from all three species. This was attenuated by theophylline, suggesting the response is mediated by P1 receptors. Ventricles were less sensitive, although high concentrations of the adenyl compounds evoked decreases in contractility. Our study suggests cardiac purinoceptors are ubiquitous across reptiles, and may play an important and underappreciated role in reptile cardiovascular physiology.


      PubDate: 2014-02-10T07:27:36Z
       
  • Time course of the acute response of the North Pacific spiny dogfish shark
           (Squalus suckleyi) to low salinity
    • Abstract: Publication date: Available online 8 February 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Samuel C. Guffey , Greg G. Goss
      Dogfish are considered stenohaline sharks but are known to briefly enter estuaries. The acute response of North Pacific spiny dogfish (Squalus suckleyi) to lowered salinity was tested by exposing sharks to 21‰ salinity for 48h. Temporal trends in blood pH, plasma osmolality, CO2, HCO3 –, Na+, Cl-, K+, and urea concentrations, and in the rates of urea efflux and O2 consumption, were quantified. The rate of O2 consumption exhibited cyclic variation and was significantly depressed by lowered salinity. After 9h, plasma [Cl-] stabilized at 9% below initial levels, while plasma [Na+] decreased by more than 20% within the first 12h. Plasma [urea] dropped by 15% between 4 and 6h, and continued to decrease. The rate of urea efflux increased over time, peaking after 36h at 72% above the initial rate. Free-swimming sharks subjected to the same salinity challenge survived over 96h and differed from cannulated sharks with respect to patterns of Na+ and urea homeostasis. This high-resolution study reveals that dogfish exposed to 21‰ salinity can maintain homeostasis of Cl- and pH, but Na+ and urea continue to be lost, likely accounting for the inability of the dogfish to fully acclimate to reduced salinity.


      PubDate: 2014-02-10T07:27:36Z
       
  • Isolation and mRNA expression analysis of aquaporin isoforms in marine
           medaka Oryzias dancena, a euryhaline teleost
    • Abstract: Publication date: Available online 28 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Yi Kyung Kim , Sang Yoon Lee , Byoung Soo Kim , Dong Soo Kim , Yoon Kwon Nam
      We have identified six putative aquaporin (AQP) genes from marine medaka Oryzias dancena (named odAQPs 1, 3, 8, 10, 11 and 12). The marine medaka AQP cDNAs encode polypeptides of 259–298 amino acids, respectively. Topology predictions showed six transmembrane domains, five connecting loops, and cytoplasmic N- and C-terminal domains, all of which is conserved among AQP molecules. Although asparagine–proline–alanine (NPA) motifs are highly conserved in most odAQP isoforms, several AQPs revealed variant types of motifs such as asparagine–proline–proline (NPP), asparagine–proline–valine (NPV) or/and asparagine–proline–serine (NPS) motifs. The phylogenic analysis showed that marine medaka AQPs had closet relationship with Japanese ricefish (medaka; Oryzias latipes) counterparts. Reverse transcription (RT)-PCR analyses showed that marine medaka AQP transcripts would be expressed in not only osmoregulatory tissues but also nonosmoregulatory tissues, and also that the expression levels of certain AQP isoforms in nonosmoregulatory tissues were readily comparable or even higher than those in typically known osmoregulatory organs. Although the overall tissue distribution patterns of AQPs were not significantly different between 0- and 30-ppt acclimated fish, the expression levels under different salinities were largely variable among isoforms and tissues. This is the first report to investigate tissue expression profiles of teleostean AQPs 11 and 12 during the long-term acclimation to freshwater and salted water.


      PubDate: 2014-01-31T22:17:12Z
       
  • Glucose metabolic gene expression in growth hormone transgenic coho salmon
    • Abstract: Publication date: Available online 29 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Stéphane Panserat , Biju Sam Kamalam , Jeanne Fournier , Elisabeth Plagnes-Juan , Krista Woodward , Robert H. Devlin
      Salmonids are generally known to be glucose intolerant. However, previous studies have shown that growth hormone (GH) transgenic coho salmon display modified nutritional regulation of glycolysis and lipogenesis compared to non-transgenic fish, suggesting the potential for better use of glucose in GH transgenic fish. To examine this in detail, GH transgenic and non-transgenic coho salmon were subjected to glucose tolerance test and subsequent metabolic assessments. After intra-peritoneal injection of 250mg/kg glucose, we analysed post-injection kinetics of glycaemia and expression of several key target genes highly involved in glucose homeostasis in muscle and liver tissues. Our data show no significant differences in plasma glucose levels during peak hyperglycaemia (3–6h after injection), demonstrating a similar glucose tolerance between transgenic and non transgenic. However, and unrelated to the hyperglycaemic episode, GH transgenic fish return to a slightly lower basal glycaemia values 24h after injection. Correspondingly, GH transgenic fish exhibited higher mRNA levels of glucokinase (GK) and glucose-6-phosphate dehydrogenase (G6PDH) in liver, and glucose transporter (GLUT4) in muscle. These data suggest that these metabolic actors may be involved in different glucose use in GH transgenic fish, which would be expected to influence the glucose challenge response. Overall, our data demonstrate that GH transgenic coho salmon may be a pertinent animal model for further study of glucose metabolism in carnivorous fish.


      PubDate: 2014-01-31T22:17:12Z
       
  • Characterization of the endocrine, digestive and morphological adjustments
           of the intestine in response to food deprivation and torpor in cunner,
           Tautogolabrus adspersus
    • Abstract: Publication date: Available online 30 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): James Hayes , Hélène Volkoff
      The cunner, Tautogolabrus adspersus, is a marine teleost endemic to the cold waters of the Northwest Atlantic Ocean. The cunner is non-migratory and is known for its remarkable ability to endure the freezing winter months with little to no food by entering a torpid/dormant state. To evaluate the physiological strategies employed by the cunner’s intestinal tract to withstand food deprivation, fish were sampled for their gut after a four-week period of acute food deprivation during their summer (active/feeding) state, as well as after 4months of overwinter fasting. Digestive capacity was evaluated by measuring digestive enzyme activity and related mRNA transcript expression for trypsin, alkaline phosphatase, alanine aminopeptidase and lipase. In order to assess how gut hormones affect/are affected by acute fasting and torpor, we examined the intestinal mRNA expression of several putative appetite regulators, i.e. CCK, apelin, orexin and mTOR. Short-term summer fasting induced a reduction in the activity, but not the transcript expression, of all digestive enzymes examined as well as a reduction in gut apelin mRNA. Torpor induced a reduction in the activity of all enzymes with the exception of alanine aminopeptidase, and a decrease in mRNA levels of alanine aminopeptidase, orexin, CCK and mTOR. Our results suggest that both acute and long-term fasting induces a reduction in the intestinal function of cunner, as evidenced by an overall decrease in the activities of digestive enzymes and mRNA expression of several factors involved in feeding and digestion.


      PubDate: 2014-01-31T22:17:12Z
       
  • Editorial Board
    • Abstract: Publication date: March 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 169




      PubDate: 2014-01-27T12:16:08Z
       
  • Vitamin C and E concentrations in muscle of elasmobranch and teleost fish
    • Abstract: Publication date: Available online 25 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marcela Vélez-Alavez , Lía C. Méndez-Rodriguez , Juan A. De Anda Montañez , C. Humberto Mejía , Felipe Galván-Magaña , Tania Zenteno-Savín
      In fish, vitamins are part of the first line of the antioxidant defense, they are directly related to stress and disease, and they are involved in the maintenance of various physiological processes and metabolic reactions. In general, fish are unable to synthesize vitamin C due to a deficiency in gulonolactone oxidase (GLO), the enzyme responsible for its de novo synthesis. Vitamin E is involved in the immune response and perhaps one of its main physiological functions is to protect membranes from oxidative damage (lipid peroxidation) associated to free radical production. In fish muscle, vitamin E has an important role as an antioxidant in vivo and its content is highly related to the stability of lipids and fats. The aim of this study was to determine the content of vitamins C and E in muscle from different species of elasmobranch and teleost fish. The concentrations of vitamin C and E were determined by high performance liquid chromatography (HPLC). The concentration of vitamin C found for the group of elasmobranchs was lower (p =0.001) than that for teleosts. For Mustelus henlei vitamin C was found in only one individual; in Tetrapturus audax and Totoaba macdonaldi vitamin C concentration was below the detection limit. The concentration of vitamin E was lower in the group of elasmobranchs (p =0.03) compared with teleosts. The main differences in the antioxidant system between teleosts and elasmobranchs appear to be the specific type and levels of antioxidant compounds, as well as the synergistic interactions among the antioxidants present in their tissues.


      PubDate: 2014-01-27T12:16:08Z
       
  • Occurrence of parotoid glands in tadpoles of the tropical frog, C
           linotarsus curtipes and their role in predator deterrence
    • Abstract: Publication date: Available online 24 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sachin M. Gosavi , Prashant S. Gaikwad , Narahari P. Gramapurohit , Ameeta Ravi Kumar
      Tadpoles of the tropical bicolored frog, Clinotarsus curtipes are unique in having parotoid glands secreting a white viscous fluid and are structurally similar to granular glands from other amphibians. To ascertain the involvement of these glands and their secretion in predator deterrence, it was tested against a predatory fish, Clarias gariepinus, using a paired choice behavioral assay. The results showed that the fish avoid eating C. curtipes tadpoles when paired with tadpoles of a sympatric species, Sylvirana temporalis. While the fish fed on C. curtipes tadpoles whose parotoid glands were surgically removed, they did not touch those with intact glands, suggesting a role for the parotid gland secretion in predator deterrence. Histochemical and biochemical analyses of the gland secretion revealed the presence of high concentrations of proteins, lipids, and alkaloids. SDS-PAGE showed the presence of proteins with prominent bands at 17 and 50kDa. The presence of other small molecules (950–2000amu) as detected by LC-MS showed the presence of five major peaks. Peaks 1 and 2 are probably tetrodotoxin and/or its analogs. Peaks 3 and 5 are possibly bufalin and arginosuccinic acid, respectively while peak 4 remains unidentified. Thus, secretion of parotoid glands of larval C. curtipes contains chemicals which, either alone or in combination, might be responsible for deterring predators.


      PubDate: 2014-01-27T12:16:08Z
       
  • Brainstem mechanisms controlling cardiovascular reflexes in channel
           catfish
    • Abstract: Publication date: Available online 13 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): J. Turesson , M.S. Hedrick , L. Sundin , M.L. Burleson
      Microinjections of kynurenic acid and kainic acid into the general visceral nucleus (nGV), homologous to the mammalian nucleus tractus solitarius of the medulla, in anesthestized, spontaneously breathing catfish were used to identify central areas and mechanisms controlling resting normoxic heart rate and blood pressure and the cardiovascular responses to hypoxia. Kynurenic acid, an antagonist of ionotropic glutamate receptors, significantly reduced resting normoxic heart rate but did not block the bradycardia associated with aquatic hypoxia. Kainic acid (an excitotoxic glutamatergic receptor agonist) also significantly reduced normoxic heart rate, but blocked the hypoxia-induced bradycardia. Neither kynurenic acid nor kainic acid microinjections affected blood pressure in normoxia or hypoxia. The results of this study indicate that glutamatergic receptors in the nGV are involved in the maintenance of resting heart rate and the destruction of these neurons with kainic acid abolishes the bradycardia associated with aquatic hypoxia.


      PubDate: 2014-01-15T04:32:43Z
       
  • Dietary live yeast alters metabolic profiles, protein biosynthesis and
           thermal stress tolerance of Drosophila melanogaster
    • Abstract: Publication date: Available online 14 January 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Hervé Colinet , David Renault
      The impact of nutritional factors on insect’s life-history traits such as reproduction and lifespan has been excessively examined; however, nutritional determinant of insect’s thermal tolerance has not received a lot of attention. Dietary live yeast represents a prominent source of proteins and amino acids for laboratory-reared drosophilids. In this study, Drosophila melanogaster adults were fed on diets supplemented or not with live yeast. We hypothesized that manipulating nutritional conditions through live yeast supplementation would translate into altered physiology and stress tolerance. We verified how live yeast supplementation affected body mass characteristics, total lipids and proteins, metabolic profiles and cold tolerance (acute and chronic stress). Females fed with live yeast had increased body mass and contained more lipids and proteins. Using GC/MS profiling, we found distinct metabolic fingerprints according to nutritional conditions. Metabolite pathway enrichment analysis corroborated that live yeast supplementation was associated with amino acid and protein biosyntheses. The cold assays revealed that the presence of dietary live yeast greatly promoted cold tolerance. Hence, this study conclusively demonstrates a significant interaction between nutritional conditions and thermal tolerance.


      PubDate: 2014-01-15T04:32:43Z
       
  • Oxidative damage and brain concentrations of free amino acid in chicks
           exposed to high ambient temperature
    • Abstract: Publication date: Available online 31 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Vishwajit S. Chowdhury , Shozo Tomonaga , Taro Ikegami , Edi Erwan , Kentaro Ito , John F. Cockrem , Mitsuhiro Furuse
      High ambient temperatures (HT) reduce food intake and body weight in young chickens, and HT can cause increased expression of hypothalamic neuropeptides. The mechanisms by which HT act, and the effects of HT on cellular homeostasis in the brain, are however not well understood. In the current study lipid peroxidation and amino acid metabolism were measured in the brains of 14 d old chicks exposed to HT (35°C for 24 or 48h) or to control thermoneutral temperature (CT; 30°C). Malondialdehyde (MDA) was measured in the brain to determine the degree of oxidative damage. HT increased body temperature and reduced food intake and body weight gain. HT also increased diencephalic oxidative damage after 48h, and altered some free amino acid concentrations in the diencephalon. Diencephalic MDA concentrations were increased by HT and time, with the effect of HT more prominent with increasing time. HT altered cystathionine, serine, tyrosine and isoleucine concentrations. Cystathionine was lower in HT birds compared with CT birds at 24h, whilst serine, tyrosine and isoleucine were higher at 48h in HT birds. An increase in oxidative damage and alterations in amino acid concentrations in the diencephalon may contribute to the physiological, behavioral and thermoregulatory responses of heat-exposed chicks.


      PubDate: 2014-01-03T22:26:22Z
       
  • The lamellae-free-type pseudobranch of the euryhaline milkfish (Chanos
           
    • Abstract: Publication date: Available online 31 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sheng-Hui Yang , Chao-Kai Kang , Hsiu-Ni Kung , Tsung-Han Lee
      In teleosts, the pseudobranch is hemibranchial, with a gill-like structure located near the first gill. We hypothesized that the pseudobranch of the milkfish might exhibit osmoregulatory ability similar to that of the gills. In this study, the obtained Na+, K+-ATPase (NKA) activity and protein abundance profiles showed that these parameters were higher in the pseudobranchs of the seawater (SW)- than the freshwater (FW)-acclimated milkfish, opposite the situation in the gills. The pseudobranch of the milkfish contained two types of NKA-immunoreactive cells, chloride cells (CCs) and pseudobranch-type cells (PSCs). To further clarify the roles of CCs and PSCs in the pseudobranch, we investigated the distributions of two ion transporters: the Na+, K+, 2Cl- cotransporter (NKCC) and the cystic fibrosis transmembrane conductance regulator (CFTR). NKCC on the basolateral membrane and CFTR on the apical membrane were found only in pseudobranchial CCs of SW-acclimated individuals. Taken together, the results distinguished NKA-IR CCs and PSCs in the pseudobranch of milkfish using antibodies against NKCC and CFTR as markers. In addition, increases in the numbers and sizes of CCs as well as in NKA expression observed upon salinity challenge indicated the potential roles of pseudobranchs in hypo-osmoregulation in this euryhaline teleost.


      PubDate: 2014-01-03T22:26:22Z
       
  • Metabolic and locomotor responses of juvenile paddlefish Polyodon spathula
           to hypoxia and temperature
    • Abstract: Publication date: Available online 22 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel L. Aboagye , Peter J. Allen
      Hypoxia is an increasing problem in the natural habitats that the paddlefish (Polyodon spathula) has historically inhabited, and a potential problem in managed culture conditions. However, the effects of hypoxia on paddlefish are not well understood. In order to understand the effects of hypoxia on juvenile paddlefish, acute hypoxia tolerance, aerobic metabolic rates and swimming capabilities were measured under normoxic (PO2 =140–155mm Hg) and hypoxic (PO2 =62–70mm Hg) conditions at 18°C and 26°C. The results showed that paddlefish acclimated to 18°C and 26°C had routine metabolic rates of 211mg/kg/h and 294mg/kg/h, respectively, with a corresponding Q10 of 1.5. At 18°C and 26°C, paddlefish had a critical partial pressure of oxygen (PO2crit) of 74mm Hg and 89mm Hg, respectively. Paddlefish had a lethal oxygen threshold of 31.0mm Hg and 37.0mm Hg at 18°C and 26°C, respectively. Further, paddlefish exhibited a reduction in swimming capability when exposed to hypoxia with a 24% and 41% decrease in Ucrit at 18°C and 26°C, respectively. Therefore, paddlefish are relatively sensitive to hypoxia, and at temperatures from 18–26°C require a dissolved oxygen concentration≥4.7mg/L to maintain basal aerobic metabolism and >2.0mg/L to survive under acute hypoxia.


      PubDate: 2013-12-25T12:16:23Z
       
  • Effects of salinity on growth and ion regulation of juvenile alligator gar
           Atractosteus spatula
    • Abstract: Publication date: Available online 22 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel E. Schwarz , Peter J. Allen
      The alligator gar (Atractosteus spatula) is a primitive euryhaline fish, found primarily in estuaries and freshwater drainages associated with the northern Gulf of Mexico. However, the extent of its hypo-osmotic regulatory abilities is not well understood. In order to determine how salinity affects growth rates and ionic and osmoregulation, juvenile alligator gar (330days after hatch; 185g) were exposed to 4 different salinities (0, 8, 16, and 24ppt) for a 30-day period. Specific growth rate, plasma osmolality and ion concentrations, gill and gastrointestinal tract Na+, K+-ATPase activities, and drinking rate were compared. Juvenile alligator gar were able to tolerate hyperosmotic salinities up to 24ppt for a 30day period, albeit with decreased growth resulting largely from decreased food consumption. Plasma osmolality and ionic concentrations were elevated in hyperosmotic salinities, and drinking rates and gastrointestinal tract Na+, K+-ATPase activities increased, particularly in the pyloric caeca, presumably the primary location of water absorption. Therefore, juvenile alligator gar<1year of age are capable of prolonged exposure to hyperosmotic salinities, but, based on the inference of these data, require access to lower salinities for long-term survival.


      PubDate: 2013-12-25T12:16:23Z
       
  • Corrigendum to “Molecular cloning of cDNA of gonadotropin-releasing
           hormones in the Chinese sturgeon (Acipenser sinensis) and the effect of
           17β-estradiol on gene expression” [Comp. Biochem. Physiol. A
           166, (2013) 529–537]
    • Abstract: Publication date: Available online 17 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Huamei Yue , Huan Ye , Xihua Chen , Hong Cao , Chuangju Li



      PubDate: 2013-12-21T07:23:43Z
       
  • Seasonal changes in humidity impact drought resistance in tropical
           Drosophila leontia: Testing developmental effects of thermal versus
           humidity changes
    • Abstract: Publication date: Available online 15 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ravi Parkash , Poonam Ranga
      D. leontia is native to highly humid equatorial tropical habitats but its desiccation sensitivity (~10h) is not consistent with its abundance during the drier autumn season in the subtropical regions. We have tested the effects of developmental acclimation on desiccation resistance and water balance related traits of D. leontia collected during rainy and autumn seasons. The isofemale lines of seasonal populations were reared under ecologically relevant growth temperatures (18 or 26°C) or humidity conditions (35 or 85 % RH) but tested at different times under identical experimental conditions. The larvae as well as flies reared under two thermal conditions (18 or 26°C) showed no effect on desiccation related traits as well as storage and utilization of energy metabolites. In contrast, for D. leontia reared under low humidity (35% RH), significant changes at larval as well adult stages include increase in the desiccation resistance as well as cuticular lipid quantity, reduced levels of rate of body water loss, higher storage of carbohydrates but lower rate of utilization of carbohydrates as compared with flies reared at high humidity (85% RH). D. leontia has responded to rearing under low humidity conditions by increasing its desiccation resistance but not due to changes in the growth temperatures. These laboratory observations on seasonal populations highlight differences due to rearing conditions but not due to seasons. Further, direct analysis of wild-caught seasonal populations has shown trends similar to developmental acclimation effects. For wild caught flies, there are significant seasonal differences i.e. higher desiccation resistance as well as cuticular lipid quantity but reduced rate of water loss for autumn than rainy season flies. Thus, our laboratory observations are relevant for understanding seasonal adaptations of natural populations of tropical D. leontia to wet-dry conditions in the wild.


      PubDate: 2013-12-17T22:19:01Z
       
  • Determinants and repeatability of the specific dynamic response of the
           corn snake, Pantherophis guttatus
    • Abstract: Publication date: Available online 17 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sarah Crocker-Buta , Stephen M. Secor
      Ingesting, digesting, absorbing, and assimilating a meal are all energy consuming processes that accumulate to form the specific dynamic action (SDA) of the meal. Sensitive to digestive demand, SDA is theoretically fixed to a given meal size and type. In this study, we explore the effects of digestive demand by altering relative meal size on the postprandial metabolic profile and SDA of the corn snake, Pantherophis guttatus. We also examined the effects of body temperature on the SDA response while controlling for meal size and type and assessed whether these responses are highly repeatable under the same conditions. Additionally, the effects of body mass on SDA were investigated by feeding snakes the same relative and absolute meal size. With increases in digestive demand (meals from 5% to 45% of body mass), P. guttatus responded with incremental increases in the postprandial peak in oxygen consumption ( V ˙ O2), the duration of the significantly elevated V ˙ O2, and SDA. Body temperature had an observable impact on the postprandial metabolic profile, decreasing the duration and increasing the peak V ˙ O2, however, body temperature did not significantly alter SDA. Regardless of temperature, and hence duration, snakes expended the same amount of energy in digesting a given meal. This was additionally borne out when testing the individual repeatability of the SDA response, individual P. guttatus exhibited nearly identical postprandial responses to the same meal. Over a 90-fold range in body mass, and fed meals equaling 25% of body mass, P. guttatus exhibited an isometric relationship between SDA and body mass. When fed a set 10-gram meal, snakes regardless of body size expended the same amount of energy on digestion and assimilation. Characteristically, P. guttatus experience a rapid postprandial increase in metabolic rate that peaks and gradually descends to prefeeding levels. The magnitude of that response (quantified as SDA) varies as a function of digestive demand (i.e., meal size); however, when demand is fixed, SDA is constant regardless of body temperature and body size.


      PubDate: 2013-12-17T22:19:01Z
       
  • Digestive flexibility during fasting in fish: A review
    • Abstract: Publication date: Available online 14 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Natalia Zaldua , Daniel E. Naya
      Digestive flexibility is important because it allows an animal to maximize energy and nutrient return from the diet consumed, and also to reduce the maintenance costs associated with one of the body’s most expensive systems in terms of energy and protein requirements. Two different patterns of digestive flexibility have been described for vertebrates, one for species in which metabolic costs of homeostasis are relatively high and the gut is rarely empty (e.g., mammals and birds), and one for species in which metabolic costs of homeostasis are relatively low and the gut usually spends long periods of time empty (e.g., amphibians and reptiles). In this review we analyze the information on digestive tract down-regulation during fasting in fish, in order to evaluate the extent to which digestive flexibility in fish conforms to that in other species. We found that: (1) Gut size decay during long-term fasting in fish appears to be almost linear with time, even for very long fasting periods. Thus, gut size temporal dynamics in fish during long-term fasting resemble those observed in some mammals species; (2) By contrast, histological changes during fasting in fish are more similar to those described for amphibians and reptiles; (3) Data on enterocyte turnover rates indicate that cell turnover times in fish are relatively short, and although longer than those observed in mammals, they are not very different from those reported for birds. In conclusion, current data suggest that both mechanisms, cell turnover rates and change in epithelial configuration, probably are involved in digestive tract regulation in fish.


      PubDate: 2013-12-17T22:19:01Z
       
  • Carbonic anhydrase induction in euryhaline crustaceans is rate-limited at
           the post-transcriptional level
    • Abstract: Publication date: Available online 12 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Reed T. Mitchell , Raymond P. Henry
      The transfer of euryhaline crustaceans from full-strength seawater to low salinity results in both a rapid up-regulation of carbonic anhydrase (CA; EC 4.2.1.1) mRNA and a slow induction of CA activity. There is a delay of several days between the two processes, which is attributed to the time required to synthesize new enzyme. These delays may also be due to limitations in the cellular uptake of Zn, which is a required post-translational active site modification to CA. To investigate these processes, the euryhaline crabs, Callinectes sapidus and Carcinus maenas, were acclimated to salinities below their isosmotic points (22.5 and 25ppt, respectively) for 7days to activate the physiological and molecular mechanisms of osmoregulation. CA mRNA increased 90-fold in C. sapidus and 2-fold in C. maenas within 6h; whereas it took 48h for the initial increases in CA activity (120% and 31%), and 4 to 7days for new acclimated levels (300% and 100%, respectively). Crabs were then transferred to lower salinities (10 and 15ppt) to induce further CA activity and to determine if previous increases in CA mRNA reduced the time required for subsequent CA induction. Additionally, the expression of the Zn transporter ZIP1 was examined in C. sapidus at 35 and 22.5ppt. In both species, prior CA mRNA elevation failed to accelerate the rate of CA induction. Levels of CA mRNA did not change in either crab following transfer from intermediate to low salinity. Taken together, these results show that the timecourse of CA induction at low salinity is not limited by the expression of CA mRNA, but by the synthesis of new enzyme from an existing pool of mRNA. No increases in ZIP1 expression occurred at low salinity, therefore these delays may be the due to the limits of cellular Zn uptake.


      PubDate: 2013-12-14T04:37:52Z
       
  • Smelling salt: Calcium as an odourant for fathead minnows
    • Abstract: Publication date: Available online 12 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): William A. Dew , Greg G. Pyle
      Calcium plays an essential role in olfactory sensory neuron function. Studies with fish have indicated that in addition to being involved in olfactory signalling, calcium is itself an odourant. In this study we used fathead minnows (Pimephales promelas) and employed two different techniques; electro-olfactography (EOG), a neurophysiological technique that measures olfactory acuity at the olfactory epithelium, and a behavioural choice assay using a trough maze. The results demonstrate that calcium and a known odourant L-arginine are cross-adaptive, that calcium induces an EOG response in a concentration-dependent manner, and that calcium induces a strong avoidance behaviour. The behavioural avoidance was also demonstrated to be olfactory-dependent. Taken together, the results demonstrate that calcium is a potent odourant for fathead minnows. Being able to smell calcium may represent an ability to sense and avoid areas with significant changes in ionic strength, thereby avoiding physiological stress.


      PubDate: 2013-12-14T04:37:52Z
       
  • Effects of environmental enrichment on growth, aggressive behaviour and
           brain monoamines of gilthead seabream Sparus aurata reared under different
           social conditions
    • Abstract: Publication date: Available online 8 December 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Alkisti Batzina , Christina Dalla , Zeta Papadopoulou-Daifoti , Nafsika Karakatsouli
      The presence of blue or red-brown substrate on tank bottom has been previously reported as an efficient means of environmental enrichment for gilthead seabream. The present study aimed to investigate whether this enrichment is still beneficial when gilthead seabream is reared under different social conditions (i.e. a lower 4.9kgm-3 and a higher 9.7kgm-3 density). Water exchange was adjusted according to fish biomass to exclude density effects on water quality. In the enriched tanks single-colour glass gravel was used as substrate (Blue and Red-Brown substrate, or BS and RBS respectively), while control tanks had no gravel. Growth, aggressive behaviour and size distribution results indicated that the lower density created a less favourable social environment. In both densities studied, BS enhanced growth, suppressed aggression and reduced brain serotonergic activity. In the condition of intense social interactions (i.e. the lower density) BS also reduced brain dopaminergic activity. These results along with the negative correlations observed between brain monoamines and fish body mass, indicated that substrate and density effects are socially-induced. However, there may be several biotic and/or abiotic factors interfering with substrate effects that should be investigated before the practical use of a substrate in land-based intensive aquaculture.


      PubDate: 2013-12-10T07:19:02Z
       
 
 
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