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  Subjects -> BIOLOGY (Total: 2575 journals)
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BIOCHEMISTRY (190 journals)                  1 2     

AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Chemical Biology     Full-text available via subscription   (Followers: 230)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 8)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 5)
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: 5)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 6)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 9)
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: 124)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 157)
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: 9)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 18)
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)
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 13)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 2)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
Biochemical Genetics     Hybrid Journal   (Followers: 2)
Biochemical Journal     Full-text available via subscription   (Followers: 14)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 2)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 3)
Biochemistry     Full-text available via subscription   (Followers: 163)
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: 4)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 8)
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: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 5)
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: 5)
BioInorganic Reaction Mechanisms     Full-text available via subscription   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 11)
Biomedicines     Open Access  
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: 18)
BMC Biochemistry     Open Access   (Followers: 8)
BMC Chemical Biology     Open Access   (Followers: 4)
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 Biology & Drug Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Journal     Hybrid Journal   (Followers: 16)
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: 3)
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)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 13)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 2)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (Followers: 2)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
FEBS Letters     Hybrid Journal   (Followers: 24)

        1 2     

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  [2563 journals]
  • PHA-induced inflammation is not energetically costly in the subterranean
           rodent Ctenomys talarum (tuco-tucos)
    • Abstract: Publication date: Available online 3 June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Julieta L. Merlo , Ana P. Cutrera , Facundo Luna , Roxana R. Zenuto
      Immune activity has been proposed to be associated with substantial costs, due to trade-offs with other functions or activities that share common resources and contribute to an animal's fitness. However, direct estimates of the cost of mounting an immune response are few and have been performed mainly in birds. Thus, further work is needed to clarify the relative costs of different components of the immune system and the role of environmental and life-history traits in modulating the costs of resistance. Within the components of immunity, inflammation is considered to be associated with a larger energetic expenditure. Here, we evaluated the energetic cost of the inflammatory response to phytohemagglutinin (PHA) in a wild population of a subterranean rodent, Ctenomys talarum, and the trade-offs between immune activity and reproduction. C. talarum develops an inflammatory response to PHA, but contrary to our predictions, this response was not associated with an increase in oxygen consumption regardless of reproductive status or sex. Our study shows that an immune challenge may not always result in a detectable energetic cost. We discuss the possibility that other currencies could be underlying the cost, such as micro-or macronutrients requirements, autoimmunity or oxidative stress.


      PubDate: 2014-06-07T16:03:50Z
       
  • Are there different requirements for trace elements in eumelanin- and
           pheomelanin-based color production' A case study of two passerine
           species
    • Abstract: Publication date: Available online 4 June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Piotr Zduniak , Adrian Surmacki , Kiraz Erciyas-Yavuz , Maria Chudzińska , Danuta Barałkiewicz
      Melanin is the most common pigment in animal integuments including bird plumage. It has been shown that several trace elements may play roles in the production and signaling function of melanin-colored plumage. We investigated coloration and content of various metal elements in the rectrices of two insectivorous passerines, Common Redstarts (Phoenicurus phoenicurus) and Blackcaps (Sylvia atricapilla), which have eumelanin- and pheomelanin-based coloration, respectively. We hypothesized that 1) the two species would differ in concentrations of metals important in melanin synthesis (Ca, Fe, Cu, Zn), 2) differences in metal concentration levels would be related to feather coloration. Our study confirmed the first prediction and provides the first evidence that selected elements may play a greater role in pheomelanin than in eumelanin synthesis. Concentrations of three elements considered as important in melanin synthesis (Ca, Fe, Zn) were 52% to 93% higher in rusty colored Common Redstart feathers compared to the dark gray Blackcap feathers. However, element concentrations were not correlated with feather coloration or sex in either species. Our study suggests that, of the two melanin forms, pheomelanin synthesis may bear higher costs associated with the acquisition of specific elements or limited elements may create trade-offs between ornamentation and other physiological functions. Our findings warrant further investigations designed to better understand the roles of macro- and microelements in the synthesis of both forms of melanin.


      PubDate: 2014-06-07T16:03:50Z
       
  • Seasonal changes and endocrine regulation of pejerrey (Odontesthes
           bonariensis) oogenesis in the wild
    • Abstract: Publication date: Available online 2 June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mariano Elisio , Tomás Chalde , Leandro A. Miranda
      The goal of this study was to evaluate the essential components controlling the brain–pituitary–gonad axis during pejerrey (Odontesthes bonariensis) oogenesis in the wild. Ovarian developmental stages from vitellogenesis up to ovulation were associated with increasing day length and water temperatures below 21°C (winter and beginning of spring). Gonadal regression was observed when water temperature exceeded this value or when photoperiod decreased. Most females were arrested at primary growth stage during summer (high temperature) or at cortical alveoli stage between autumn and beginning of winter (short photoperiod). Plasma E2 and transcript levels of fshr, cyp19a1b and cyp19a1a increased during vitellogenesis, while fshb remained high at all vitellogenic stages. A significant correlation between plasma sex steroids (T and E2) and cyp19a1b as well as lhcgr transcript levels was observed during vitellogenesis, suggesting a steroid positive feedback. Gnrh-I, Gth subunits and lhcgr transcript levels increased significantly during late vitellogenesis and final maturation. Present results suggest that pejerrey vitellogenesis is controlled by Fsh/Fshr, stimulating gonadal aromatase and estradiol synthesis. Moreover, the increase of testosterone and estradiol during final vitellogenesis could induce coordinately the functioning of the Gnrh/Lh system (perhaps through brain P450 aromatase stimulation and brain estradiol increase) and the gonadal Lhcgr synthesis to promote the final maturation of oocytes. All these stimulation mechanisms of gonadal development would be possible only under permissive environmental conditions.


      PubDate: 2014-06-07T16:03:50Z
       
  • Acute exposure to a common suspended sediment affects the swimming
           performance and physiology of juvenile salmonids
    • Abstract: Publication date: Available online 6 June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Barbara I. Berli , Matthew J.H. Gilbert , Allison L. Ralph , Keith B. Tierney , Patricia Burkhardt-Holm
      To study the effects of an acute exposure to turbidity generated by suspended sediment, we examined swimming performance (U crit) and related metabolic parameters in individual and groups of juvenile trout at three different concentrations of calcium carbonate. To investigate differences among strains or provenience, we compared one strain of rainbow trout (Oncorhynchus mykiss; RBT) and one strain of brown trout (Salmo trutta; BNT) from a common hatchery and one RBT strain from a separate hatchery. In general, trout swum individually or in groups exhibited a decrease in U crit as turbidity increased. Both RBT strains were more similar to each other and were impaired to a larger extent in swimming performance than BNT, which was less impacted. For groups, indicators of aerobic metabolism were elevated while those of anaerobic metabolism were depressed. Specifically, citrate synthase activities and glucose levels tended to be greater while plasma lactate and LDH activities were reduced. Lactate and LDH levels in individually swum trout under sediment exposure suggest a greater similarity of fish from the same provenience. We suggest that acute exposures to environmentally relevant turbidities generated by fine suspended sediment may cause a reduced U crit, and that these changes may be related to changes in the utilization of aerobic and anaerobic pathways.


      PubDate: 2014-06-07T16:03:50Z
       
  • The effects of exogenous cortisol on myostatin transcription in rainbow
           trout, Oncorhynchus mykiss
    • Abstract: Publication date: Available online 27 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Nicholas J. Galt , Jacob Michael Froehlich , Ethan A. Remily , Sinibaldo R. Romero , Peggy R. Biga
      Glucocorticoids (GCs) strongly regulate myostatin transcript levels in mammals via glucocorticoid response elements (GREs) in the myostatin promoter, and bioinformatics methods suggest that this regulatory mechanism is conserved among many vertebrates. However, the multiple myostatin genes found in some fishes may be an exception. In rainbow trout (Oncorhynchus mykiss), two genome duplication events have produced three putatively functional myostatin genes, myostatin-1a, -1b and -2a, which are ubiquitously and differentially expressed. In addition, in silico promoter analyses of the rainbow trout myostatin promoters have failed to identify putative GREs, suggesting a divergence in myostatin function. Therefore, we hypothesized that myostatin mRNA expression is not regulated by glucocorticoids in rainbow trout. In this study, both juvenile rainbow trout and primary trout myoblasts were treated with cortisol to examine the relationship between this glucocorticoid and myostatin mRNA expression. Results suggest that exogenous cortisol does not regulate myostatin-1a and -1b expression in vivo, as myostatin mRNA levels were not significantly affected by cortisol treatment in either red or white muscle tissue. In red muscle, myostatin-2a levels were significantly elevated in the cortisol treatment group relative to the control, but not the vehicle control, at both 12h and 24h post-injection. As such, it is unclear if cortisol was acting alone or in combination with the vehicle. Cortisol increased myostatin-1b expression in a dose-dependent manner in vitro. Further work is needed to determine if this response is the direct result of cortisol acting on the myostatin-1b promoter or through an alternative mechanism. These results suggest that regulation of myostatin by cortisol may not be as highly conserved as previously thought and support previous work that describes potential functional divergence of the multiple myostatin genes in fishes.


      PubDate: 2014-06-01T14:41:21Z
       
  • Molecular responses of fishes to elevated carbon dioxide
    • Abstract: Publication date: Available online 26 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Clark E. Dennis III , Daniel F. Kates , Matthew R. Noatch , Cory D. Suski
      Hypercarbia, or elevated carbon dioxide, is an environmental challenge that can have detrimental effects on the physiology and performance of aquatic organisms. With aquatic hypercarbia predicted to become more prevalent in the future due to global climate change, it is important to quantify how hypercarbia impacts aquatic organisms, especially fish. The impact of hypercarbia on the behavior and physiology of fishes has been well studied, but relatively few studies have examined the molecular processes that underlie resulting behavioral and physiological changes. In an effort to define the molecular response of fishes to acute hypercarbia exposure, bluegill (Lepomis macrochirus) and silver carp (Hypophthalmichthys molitrix) were exposed to either 30mgL-1 CO2 (pCO2 ≈15700 μatm) or ambient (10mgL-1 CO2; pCO2 ≈920 μatm) conditions for 1h and the expression of a variety of genes, across three tissues, were compared. Exposure to 30mgL-1 CO2 in bluegill and silver carp resulted in an increase in c-Fos, HIF1-α, and GR-2 transcripts, while silver carp alone showed increases in Hsp70 and Hsc70-2 mRNA. This study demonstrates that acute hypercarbia exposure impacts gene expression in a species and tissue specific manner, which can be useful in identifying potential mechanisms for hypercarbia tolerance between species, and pinpoint specific tissues that are sensitive to hypercarbia exposure.


      PubDate: 2014-06-01T14:41:21Z
       
  • Adipose tissue and liver metabolic responses to different levels of
           dietary carbohydrates in gilthead sea bream (Sparus aurata)
    • Abstract: Publication date: Available online 26 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marta Bou , Marijana Todorčević , Ramón Fontanillas , Encarnación Capilla , Joaquim Gutiérrez , Isabel Navarro
      This study analyzes the effects of replacing dietary lipids by carbohydrates and carbohydrates by fiber on gilthead sea bream growth, as well as lipid and glucose metabolism in adipose tissue and liver over the course of a 15-week feeding trial. Six different diets were formulated and fish were classified into two experimental groups sharing one diet. In the first group (LS), fish were fed four diets where lipids were reduced (23%–17%) by increasing carbohydrates (12%–28%) and, the second group (SF) consisted on three diets where the amount of carbohydrates (28%–11%) was exchanged at expenses of fiber (1%–18%). Differences in growth were not observed; nevertheless, the hepatosomatic index was positively related to dietary starch levels, apparently not due to enhanced hepatic lipogenesis, partly supported by unchanged G6PDH expression. In the LS group, lipogenic activity of adipose tissue was stimulated with low-lipid/high-carbohydrate diets by up-regulating G6PDH expression and a tendency to increase FAS, and promoted carbohydrate utilization versus fatty acid oxidation by modulating the transcription factors LXRα, PPARα and PPARβ expression. In the SF group, PPARs and LXRα increased parallel to fiber levels in adipose tissue. Furthermore, an adaptation of hepatic GK to dietary starch inclusion was observed in both groups; however, the lack of effects on G6Pase expression indicated that gluconeogenesis was not nutritionally regulated under the conditions examined. Overall, metabolic adaptations directed to an efficient use of dietary carbohydrates are present in gilthead sea bream, supporting the possibility of increasing the carbohydrate or fiber content in diets for aquaculture sustainability.


      PubDate: 2014-06-01T14:41:21Z
       
  • Editorial Board
    • Abstract: Publication date: August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 174




      PubDate: 2014-05-25T16:17:33Z
       
  • Ontogeny of non-shivering thermogenesis in Muscovy ducklings (Cairina
           moschata)
    • Abstract: Publication date: Available online 23 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Loïc Teulier , Jean-Louis Rouanet , Benjamin Rey , Damien Roussel
      In precocial birds, developing the capacity for early regulatory thermogenesis appears as a fundamental prerequisite for survival and growth in cold environments. However, the exact nature of these processes has not been thoroughly investigated. Several bird species, such as Muscovy ducks (Cairina moschata), develop muscular non-shivering thermogenesis when chronically exposed to cold. The aim of this study was to investigate the age-dependent development of non-shivering thermogenesis in ducklings reared either at thermoneutrality (25°C) or in the cold (4°C). Non-shivering thermogenesis was assessed weekly by simultaneously measuring whole body metabolic heat production and electromyographic activity during shivering at different temperatures ranging from 29°C to 0°C. We found that ducklings reared at thermoneutrality displayed a capacity for non-shivering thermogenesis during the first month of post-hatching life. This thermogenic mechanism increased further in ducklings chronically exposed to a cold environment, but it decreased over time when birds were kept in a thermoneutral environment.


      PubDate: 2014-05-25T16:17:33Z
       
  • Developmental acclimation to low or high humidity conditions affect
           starvation and heat resistance of Drosophila melanogaster
    • Abstract: Publication date: Available online 17 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ravi Parkash , Poonam Ranga , Dau Dayal Aggarwal
      Populations of several Drosophila species originating from tropical humid localities are more resistant to starvation as well as heat than populations from high latitudes but mechanistic bases of such physiological changes are largely unknown. In order to test whether humidity levels affect starvation survival and heat resistance, we investigated developmental acclimation effects of low to high humidity conditions on the storage and utilization of energy resources, body mass, starvation survival, heat knockdown and heat survival of Drosophila melanogaster. Isofemale lines reared under higher humidity (85% RH) stored significantly higher level of lipids and showed greater starvation survival hours but flies were smaller in body size. In contrast, lines reared at high humidity evidenced reduced levels of body lipids and starvation resistance. Starvation resistance and lipid storage level were higher in females than in males. However, the rate of utilization of lipids under starvation stress was lower for lines reared under higher humidity. Adult flies of lines reared at 65% RH and acclimated under high or low humidity condition for 200h also showed changes in resistance to starvation and heat stress but such effects were significantly lower as compared with developmental acclimation. Isofemale lines reared under higher humidity showed greater heat knockdown time as well as heat-shock survival. These laboratory observations on developmental and adult acclimation effects of low versus high humidity conditions have helped in explaining seasonal changes (rainy versus autumn) in resistance to starvation and heat of the wild-caught flies of D. melanogaster. Thus, we may suggest that wet versus drier conditions significantly affect starvation and heat resistance of D. melanogaster.


      PubDate: 2014-05-25T16:17:33Z
       
  • Inhibition of the cardiac ATP-dependent potassium current by KB-R7943
    • Abstract: Publication date: Available online 17 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Denis V. Abramochkin , Matti Vornanen
      KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea) was developed as a specific inhibitor of the sarcolemmal sodium–calcium exchanger (NCX) with potential experimental and therapeutic use. However, in cardiomyocytes KB-R7943 also effectively blocks several K+ currents including the delayed rectifier, IKr. Recently, the background inward rectifier (IK1) and the acetylcholine-induced inward rectifier (IKACh) were shown to be sensitive to KB-R7943 block in mammalian and fish cardiomyocytes. In the present study we analyze the effects of KB-R7943 on the ATP-dependent potassium current (IKATP) recorded by whole-cell patch-clamp in ventricular cardiomyocytes from a mammal (mouse) and a fish (crucian carp). IKATP was induced by external application of a mitochondrial uncoupler CCCP (3×10−7 M) and internal perfusion of the cell with ATP-free pipette solution. A weakly inwardly rectifying current with a large outward component, recorded in the presence of CCCP, was blocked with 10−5 M glibenclamide by 56.1±4.6% and 56.9±3.6% in crucian carp and mouse ventricular myocytes, respectively. In fish cardiomyocytes IKATP was blocked by KB-R7943 with an IC50 value of 3.14×10−7 M, while in mammalian cells IC50 was 2.8×10−6 M (P<0.05). 10−5 M KB-R7943 inhibited CCCP-induced IKATP by 99.9±0.13% and 97.5±1.2% in crucian carp and mouse ventricular myocytes, respectively. In crucian carp the IKATP is about an order of magnitude more sensitive to KB-R7943 than the background IK1, but in mammals IKATP and IK1 are almost equally sensitive to KB-R7943. Therefore, the ability of KB-R7943 to block IKATP should be taken into account together with INCX inhibition when investigating possible cardioprotective effects of this compound.


      PubDate: 2014-05-25T16:17:33Z
       
  • Alterations in gill structure in tropical reef fishes as a result of
           elevated temperatures
    • Abstract: Publication date: Available online 23 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): A.J. Bowden , N.M. Gardiner , C.S. Couturier , J.A.W. Stecyk , G.E. Nilsson , P.L. Munday , J.L. Rummer
      Tropical regions are expected to be some of the most affected by rising sea surface temperatures (SSTs) because seasonal temperature variations are minimal. As temperatures rise, less oxygen dissolves in water, but metabolic requirements of fish and thus, the demand for effective oxygen uptake, increases. Gill remodelling is an acclimation strategy well documented in freshwater cyprinids experiencing large seasonal variations in temperature and oxygen as well as an amphibious killifish upon air exposure. However, no study has investigated whether tropical reef fishes remodel their gills to allow for increased oxygen demands at elevated temperatures. We tested for gill remodelling in five coral reef species (Acanthochromis polyacanthus, Chromis atripectoralis, Pomacentrus moluccensis, Dascyllus melanurus and Cheilodipterus quinquelineatus) from populations in northern Papua New Guinea (2° 35.765' S; 150° 46.193' E). Fishes were acclimated for 12–14 days to 29 and 31°C, encompassing their seasonal range (29–31°C), and 33 and 34°C to account for end-of-century predicted temperatures. We measured lamellar perimeter, cross-sectional area, base thickness, and length for five filaments on the 2nd gill arches and qualitatively assessed 3rd gill arches via scanning electron microscopy (SEM). All species exhibited significant differences in the quantitative measurements made on the lamellae, but no consistent trends with temperature were observed. SEM only revealed alterations in gill morphology in P. moluccensis. The overall lack of changes in gill morphology with increasing temperature suggests that these near-equatorial reef fishes may fail to maintain adequate O2 uptake under future climate scenarios unless other adaptive mechanisms are employed.


      PubDate: 2014-05-25T16:17:33Z
       
  • Ecophysiology of native and alien invasive clams in an ocean warming
           context
    • Abstract: Publication date: Available online 15 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Patrícia Anacleto , Ana Luísa Maulvault , Vanessa M. Lopes , Tiago Repolho , Mário Diniz , Maria Leonor Nunes , António Marques , Rui Rosa
      Both climate change and biological invasions are among the most serious global environmental threats. Yet mechanisms underlying these eventual interactions remain unclear. The aim of this study was to undertake a comprehensive examination of the physiological and biochemical responses of native (Ruditapes decussatus) and alien invasive (Ruditapes philippinarum) clams to environmental warming. We evaluated thermal tolerance limits (CTMax), routine metabolic rates (RMR) and respective thermal sensitivity (Q10 values), critical oxygen partial pressure (Pcrit), heat shock response (HSP70/HSC70 levels), lipid peroxidation (MDA build-up) and antioxidant enzyme [glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD)] activities. Contrary to most studies that show that invasive species have a higher thermal tolerance than native congeners, here we revealed that the alien invasive and native species had similar CTMax values. However, warming had a stronger effect on metabolism and oxidative status of the native R. decussatus, as indicated by the higher RMR, HSP70/HSC70 and MDA levels, as well as GST, CAT and SOD activities. Moreover, we argue that the alien invasive clams, instead of up-regulating energetically expensive cellular responses, have evolved a less demanding strategy to cope with short-term environmental (oxidative) stress – pervasive valve closure. Although efficient during stressful short-term periods to ensure isolation and guarantee longer survival, such adaptive behavioural strategy entails metabolic arrest (and the enhancement of anaerobic pathways), which to some extent, will not be advantageous under the chronically warming conditions predicted in the future.


      PubDate: 2014-05-20T06:21:56Z
       
  • Derivation of a continuous myogenic cell culture from an embryo of common
           killifish, Fundulus heteroclitus
    • Abstract: Publication date: Available online 13 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sarah J. Gignac , Nguyen T.K. Vo , Michael S. Mikhaeil , J. Andrew N. Alexander , Deborah L. MacLatchy , Patricia M. Schulte , Lucy E.J. Lee
      The common killifish or mummichog (Fundulus heteroclitus) is an estuarine teleost increasingly used in comparative physiology, toxicology and embryology. Their ability to withstand extreme environmental conditions and ease of maintenance has made them popular aquatic research organisms. Scientific advances with most popular model organisms have been assisted with the availability of continuous cell lines; however, cell lines from F. heteroclitus appears to be unavailable. The development of a killifish cell line, KFE-5, derived from the mid trunk region of a late stage embryo is described here. KFE-5 grows well in Leibovitz’s L-15 media with 10% fetal bovine serum (FBS). This cell line has been passaged over 60 times in a span of three years, and cells at various passages have been successfully cryopreserved and thawed. The cells are mostly fibroblastic but contain myogenic cells that differentiate into mono-, bi- and multi-nucleated striated myocytes. Immunofluorescence detection of muscle specific antigens such as α-actinin, desmin, myosin confirms KFE-5 as a myogenic cell line. KFE-5 has a temperature preference for 26-28°C and has been shown to withstand temperatures up to 37°C. The cell line responds to chemical signals including growth factors, hormones and extracellular matrix components. KFE-5 could thus be useful not only for mummichog’s thermobiology but also for studies in fish muscle physiology and development.


      PubDate: 2014-05-15T06:27:24Z
       
  • H2S exposure elicits differential expression of candidate genes in fish
           adapted to sulfidic and non-sulfidic environments
    • Abstract: Publication date: Available online 9 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Michael Tobler , Chathurika Henpita , Brandon Bassett , Joanna L. Kelley , Jennifer H. Shaw
      Disentangling the effects of plasticity, genetic variation, and their interactions on organismal responses to environmental stressors is a key objective in ecological physiology. We quantified the expression of five candidate genes in response to hydrogen sulfide (H2S) exposure in fish (Poecilia mexicana, Poeciliidae) from a naturally sulfide-rich environment as well as an ancestral, non-sulfidic population to test for constitutive and environmentally dependent population differences in gene expression patterns. Common garden raised individuals that had never encountered environmental H2S during their lifetime were subjected to short or long term H2S exposure treatments or respective non-sulfidic controls. The expression of genes involved in responses to H2S toxicity (cytochrome c oxidase, vascular endothelial growth factor, and cytochrome P450-2J6), H2S detoxification (sulfide:quinone oxidoreductase), and endogenous H2S production (cystathionine γ lyase) was determined in both gill and liver tissues by real time PCR. The results indicated complex changes in expression patterns that – depending on the gene – not only differed between organs and populations, but also on the type of H2S exposure. Populations differences, both constitutive and H2S exposure dependent (i.e., plastic), in gene expression were particularly evident for sulfide:quinone oxidoreductase, vascular endothelial growth factor, and to a lesser degree for cytochrome P450-2J6. Our study uncovered putatively adaptive modifications in gene regulation that parallel previously documented adaptive changes in phenotypic traits.


      PubDate: 2014-05-10T06:28:20Z
       
  • Evidence for intraspecific endocrine disruption of Geukensia demissa
           (Atlantic ribbed mussel) in an urban watershed
    • Abstract: Publication date: Available online 9 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Zachery M. Halem , Dustin J. Ross , Rachel L. Cox
      Populations undergo physiological adaptations in response to environmental stressors. Our five-year bio-monitoring study of the Bronx River Estuary demonstrates comparatively low dissolved oxygen concentrations in this urbanized watershed. Additionally, our current results establish altered hormonal levels, resulting from endocrine disruption, in Geukensia demissa (Atlantic ribbed mussel) from the Bronx River Estuary. No studies have yet investigated a correlation between low dissolved oxygen and endocrine disruption in field-collected bivalves. Testosterone, estradiol, and progesterone levels were collected from male and female mussels in the oxygen depleted Bronx River and well-oxygenated Greenwich Cove. Bronx River mussels exhibited higher testosterone levels and lower estradiol levels than Greenwich Cove mussels. The resulting abnormal hormonal ratio seems to indicate that environmental conditions in the Bronx River facilitate an allosteric inhibition of the cytochrome P450 aromatase enzyme, which aids conversion of testosterone to estradiol. Low progesterone levels suggest Bronx River mussels are experiencing a delay in sexual maturation, and morphometric data show a stalling of shell and tissue growth. To confirm that the mussels collected from both sites are the same species, the universal mitochondrial cytochrome c oxidase subunit I gene was analyzed, through DNA barcoding. Minimal sequential heterogeneity confirmed the mussels are the same species. Such findings suggest intraspecific divergence in various endocrine processes, resulting from environmentally induced stress.


      PubDate: 2014-05-10T06:28:20Z
       
  • Tracheole investment does not vary with body size among bumblebee (Bombus
           impatiens) sisters
    • Abstract: Publication date: Available online 9 May 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jessica R. Vogt , Megan K. Dillon , Michael E. Dillon
      Body size is a key organism trait with critical implications for the physiology, life history, and ecology of organisms. Modern insects vary in body mass by over 6 orders of magnitude, but are small by comparison to many other metazoan taxa. The small size of modern insects may reflect limitations imposed by their open respiratory systems which rely, in part, on diffusion. Diffusion rates decline with distance such that, absent compensation, the capacity for larger insects to deliver oxygen to their tissues may be compromised. To compensate, larger grasshoppers, beetles, and bumblebees devote proportionally more of their body volume to the respiratory system, as demonstrated by hypermetric scaling of tracheal volume with body mass>1. Among bumblebee sisters, total respiratory volume scaled with mass2.6, but it is unclear at what level or levels of the tracheal system (main tracheal trunks, air sacs, tracheoles) bumblebees express this extreme hypermetry. Here we use transmission electron microscopy to examine morphology of tracheoles in bumblebee flight muscle among sister bumblebees varying nearly four-fold in body mass. Neither tracheole density nor tracheole diameter changed with body mass. The total cross-sectional area of tracheoles was also invariant with body mass. Together, these results reveal that bumblebees do not compensate for size-related limitations on oxygen delivery by increasing investment at the level of the tracheoles.


      PubDate: 2014-05-10T06:28:20Z
       
  • Euechinoidea and Cidaroidea respond differently to ocean acidification
    • Abstract: Publication date: Available online 29 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marie Collard , Aurélie Dery , Frank Dehairs , Philippe Dubois
      The impact of the chemical changes in the ocean waters due to the increasing atmospheric CO2 depends on the ability of an organism to control extracellular pH. Among sea urchins, this seems specific to the Euechinoidea, sea urchins except Cidaroidea. However, Cidaroidea survived two ocean acidification periods: the Permian-Trias and the Cretaceous-Tertiary crises. We investigated the response of these two sea urchin groups to reduced seawater pH with the tropical cidaroid Eucidaris tribuloides, the sympatric euechinoid Tripneustes ventricosus and the temperate euechinoid Paracentrotus lividus. Both euechinoids showed a compensation of the coelomic fluid pH due to increased buffer capacity at reduced seawater pH. This was linked to an increased concentration of DIC in the coelomic fluid and thus of bicarbonate ions (most probably originating from the surrounding seawater as isotopic signature of the carbon - δ13C - were similar). On the other hand, the cidaroid showed no changes within the coelomic fluid. Moreover, the δ13C of the coelomic fluid did not match that of the seawater and was not significantly different between the urchins from the different treatments. Feeding rate was not affected in any species. While euechinoids are able to regulate their extracellular acid-base balance, many questions are still unanswered on the costs of this capacity. On the contrary, cidaroids do not seem affected by a reduced seawater pH. Further investigations need to be undertaken to cover more species, physiological and metabolic parameters in order to determine if energy trade-offs occur and how this mechanism of compensation is distributed among sea urchins.


      PubDate: 2014-04-30T06:27:37Z
       
  • Feeding induces translocation of vacuolar proton ATPase and pendrin to the
           membrane of leopard shark (Triakis semifasciata) mitochondrion-rich gill
           cells
    • Abstract: Publication date: Available online 16 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jinae N. Roa , Christian L. Munévar , Martin Tresguerres
      In this study we characterized mitochondrion-rich (MR) cells and regulation of acid/base (A/B) relevant ion-transporting proteins in leopard shark (Triakis semifasciata) gills. Immunohistochemistry revealed that leopard shark gills posses two separate cell populations that abundantly express either Na+/K+-ATPase (NKA) or V-H+-ATPase (VHA), but not both ATPases together. Co-immunolocalization with mitochondrial Complex IV demonstrated, for the first time in shark gills, that both NKA- and VHA-rich cells are also MR cells, and that all MR cells are either NKA- or VHA-rich cells. Additionally we localized the anion exchanger pendrin to VHA-rich cells, but not NKA-rich cells. In starved sharks, VHA was localized throughout the cell cytoplasm and pendrin was present at the apical pole (but not in the membrane). However, in a significant number of gill cells from fed leopard sharks, VHA translocated to the basolateral membrane (as previously described in dogfish), and pendrin translocated to the apical membrane. Our results highlight the importance of translocation of ion-transporting proteins to the cell membrane as a regulatory mechanism for A/B regulation.


      PubDate: 2014-04-20T06:44:38Z
       
  • Expressional regulation of key hepatic enzymes of intermediary metabolism
           in European seabass (Dicentrarchus labrax) during food deprivation and
           refeeding
    • Abstract: Publication date: Available online 18 April 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ivan Viegas , Albert Caballero-Solares , João Rito , Marina Giralt , Miguel A. Pardal , Isidoro Metón , John G. Jones , Isabel V. Baanante
      We hypothesized that the analysis of mRNA level and activity of key enzymes in amino acid and carbohydrate metabolism in a feeding/fasting/refeeding setting could improve our understanding of how a carnivorous fish, like the European seabass (Dicentrarchus labrax), responds to changes in dietary intake at the hepatic level. To this end cDNA fragments encoding genes for cytosolic and mitochondrial alanine aminotransferase (cALT; mALT), pyruvate kinase (PK), glucose 6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) were cloned and sequenced. Measurement of mRNA levels through quantitative real-time PCR performed in livers of fasted seabass revealed a significant increase in cALT (8.5-fold induction) while promoting a drastic 45-fold down-regulation of PK in relation to the levels found in fed seabass. These observations were corroborated by enzyme activity meaning that during food deprivation an increase in the capacity of pyruvate generation happened via alanine to offset the reduction in pyruvate derived via glycolysis. After a 3-day refeeding period cALT returned to control levels while PK was not able to rebound. No alterations were detected in the expression levels of G6PDH while 6PGDH revealed to be more sensitive specially to fasting, as confirmed by a significant 5.7-fold decrease in mRNA levels with no recovery after refeeding. Our results indicate that in early stages of refeeding, the liver prioritized the restoration of systemic normoglycemia and replenishment of hepatic glycogen. In a later stage, once regular feeding is re-established, dietary fuel may then be channeled to glycolysis and de novo lipogenesis.


      PubDate: 2014-04-20T06:44:38Z
       
  • 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
       
  • 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
       
  • 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
       
 
 
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