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BIOCHEMISTRY (214 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 8)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Chemical Biology     Full-text available via subscription   (Followers: 179)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
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African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 6)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 79)
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American Journal of Polymer Science     Open Access   (Followers: 20)
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Annual Review of Biochemistry     Full-text available via subscription   (Followers: 31)
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Asian Journal of Biochemistry     Open Access   (Followers: 1)
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Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
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Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 3)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 5)
ChemBioChem     Hybrid Journal   (Followers: 2)
Chemical and Biological Technologies for Agriculture     Open Access  
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Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
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ChemTexts     Hybrid Journal  
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 4)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 8)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 3)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)

        1 2 3     

Journal Cover   Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2812 journals]
  • Carotenoid-based coloration in cichlid fishes
    • Abstract: Publication date: July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 173
      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: 2015-06-20T16:50:39Z
  • Damage caused during hypoxia and reoxygenation in the locomotor muscle of
           the crab Neohelice granulata (Decapoda: Varunidae)
    • Abstract: Publication date: June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 172
      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 (0.5mgO2 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: 2015-06-20T16:50:39Z
  • Evidence for intraspecific endocrine disruption of Geukensia demissa
           (Atlantic ribbed mussel) in an urban watershed
    • Abstract: Publication date: September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 175
      Author(s): Zachery M. Halem , Dustin J. Ross , Rachel L. Cox
      Populations undergo physiological adaptations in response to environmental stressors. Our 5-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 that 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: 2015-06-20T16:50:39Z
  • Distinct patterns of water and osmolyte control between intertidal
           (Bunodosoma caissarum) and subtidal (Anemonia sargassensis) sea anemones
    • Abstract: Publication date: April 2011
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 158, Issue 4
      Author(s): Enelise M. Amado , Denilton Vidolin , Carolina A. Freire , Marta M. Souza
      Anemones are frequently found in rocky intertidal coasts. As they have highly permeable body surfaces, exposure to the air or to salinity variations inside tidal pools can represent intense osmotic and ionic challenges. The intertidal Bunodosoma caissarum has been compared with the subtidal Anemonia sargassensis concerning their response to air exposure or salinity changes. B. caissarum maintains tissue hydration through mucus production and dome-shape formation when challenged with air exposure or extreme salinities (fresh water or hypersaline seawater, 45psu) for 1–2h. Upon exposure to mild osmotic shocks for 6h (hyposmotic: 25psu, or hyperosmotic: 37psu), B. caissarum was able to maintain its coelenteron fluid (CF) osmolality stable, but only in 25psu. A. sargassensis CF osmolality followed the external medium in both salinities. Isolated cells of the pedal disc of B. caissarum showed full capacity for calcium-dependent regulatory volume decrease (RVD) upon 20% hyposmotic shock, at least partially involving the release of KCl via K+–Cl− cotransport, and also of organic osmolytes. Aquaporins (HgCl2-inhibited) likely participate in this process. Cells of A. sargassensis showed partial RVD, after 20min. Cells from both species were not capable of regulatory volume increase upon hyperosmotic shock (20%). Whole organism and cellular mechanisms allow B. caissarum to live in the challenging intertidal habitat, frequently facing air exposure and seawater dilution.

      PubDate: 2015-06-20T16:50:39Z
  • Differences in oxygen consumption and diel activity as adaptations related
           to microhabitat in Neotropical freshwater decapods (Crustacea)
    • Abstract: Publication date: December 2011
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 160, Issue 4
      Author(s): Marcelo Dalosto , Sandro Santos
      This study evaluated oxygen consumption (MO2) and diel activity in Aegla longirostri, Trichodactylus panoplus and Parastacus brasiliensis (three species of freshwater decapods that occur in sympatry), under two different conditions of O2 availability, limited and constant; and searched for the existence of a relationship between these two variables. The Kruskal–Wallis test showed that in all the species, MO2 was higher under constant O2 availability; T. panoplus and P. brasiliensis showed an oxygen-dependent pattern, while A. longirostri showed higher MO2 values and less variation in the values between the treatments, indicating a higher and more oxygen-independent metabolism. P. brasiliensis was more active in constant O2. A. longirostri was more active in limited O2 and did not show a clear diel activity in any case, showing behavioral changes when in unfavorable conditions. The Spearman's rank correlation analysis did not indicate any relationship between MO2 and activity. These results indicate a higher metabolism in A. longirostri. The less demanding metabolisms of P. brasiliensis and T. panoplus allow these species to occupy environments that are unavailable to A. longirostri due to differences in dissolved-oxygen concentrations.

      PubDate: 2015-06-20T16:50:39Z
  • Responses of free radical metabolism to air exposure or salinity stress,
           in crabs (Callinectes danae and C. ornatus) with different estuarine
    • Abstract: Publication date: October 2011
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 160, Issue 2
      Author(s): Carolina A. Freire , Valéria G. Togni , Marcelo Hermes-Lima
      The swimming crabs Callinectes danae and C. ornatus are found in bays and estuaries, but C. danae is more abundant in lower salinities, while C. ornatus remains restricted to areas of higher salinity. Experimental crabs of both species were submitted to: air exposure (Ae, 3h), reimmersion in 33‰ (control) sea water (SW) (Ri, 1h) following air exposure; hyposaline (Ho, 10‰ for 2h) or hypersaline (He, 40‰ for 2h) SW, then return to control 33‰ SW (RHo and RHe, for 1h). Hemolymph was sampled for osmolality and chloride determinations. Activity of antioxidant enzymes [glutathione peroxidase (GPX), catalase, glutathione-S-transferase] and levels of carbonyl proteins and lipid peroxidation (TBARS) were evaluated in hepatopancreas, muscle, anterior and posterior gills. In Ho groups, hemolymph concentrations were lower in both species, compared to He groups. C. danae displayed higher control activities of GPX (hepatopancreas and muscle) and catalase (all four tissues) than C. ornatus. C. ornatus presented increased activities of catalase and GPX in Ae, Ri, and He groups. Increased TBARS was seen in C. ornatus tissues (He group). The more euryhaline species displayed higher constitutive activities of antioxidant enzymes, and the less euryhaline species exhibited activation of these enzymes when exposed to air or hyper-salinity.

      PubDate: 2015-06-20T16:50:39Z
  • The breathing pattern and the ventilatory response to aquatic and aerial
           hypoxia and hypercarbia in the frog Pipa carvalhoi
    • Abstract: Publication date: July 2012
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 162, Issue 3
      Author(s): Elisa M. Fonseca , Glauber S.F. da Silva , Marcelo Fernandes , Humberto Giusti , Carolina R. Noronha-de-Souza , Mogens L. Glass , Kênia C. Bícego , Luciane H. Gargaglioni
      Anuran amphibians are known to exhibit an intermittent pattern of pulmonary ventilation and to exhibit an increased ventilatory response to hypoxia and hypercarbia. However, only a few species have been studied to date. The aquatic frog Pipa carvalhoi inhabits lakes, ponds and marshes that are rich in nutrients but low in O2. There are no studies of the respiratory pattern of this species and its ventilation during hypoxia or hypercarbia. Accordingly, the aim of the present study was to characterize the breathing pattern and the ventilatory response to aquatic and aerial hypoxia and hypercarbia in this species. With this purpose, pulmonary ventilation (VI) was directly measured by the pneumotachograph method during normocapnic normoxia to determine the basal respiratory pattern and during aerial and aquatic hypercarbia (5% CO2) and hypoxia (5% O2). Our data demonstrate that P. carvalhoi exhibits a periodic breathing pattern composed of single events (single breaths) of pulmonary ventilation separated by periods of apnea. The animals had an enhanced VI during aerial hypoxia, but not during aquatic hypoxia. This increase was strictly the result of an increase in the breathing frequency. A pronounced increase in VI was observed if the animals were simultaneously exposed to aerial and aquatic hypercarbia, whereas small or no ventilatory responses were observed during separately administered aerial or aquatic hypercarbia. P. carvalhoi primarily inhabits an aquatic environment. Nevertheless, it does not respond to low O2 levels in water, although it does so in air. The observed ventilatory responses to hypercarbia may indicate that this species is similar to other anurans in possessing central chemoreceptors.

      PubDate: 2015-06-20T16:50:39Z
  • Nitrogen excretion during embryonic development of the green iguana,
           Iguana iguana (Reptilia; Squamata)
    • Abstract: Publication date: October 2012
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 163, Issue 2
      Author(s): M.R. Sartori , E.W. Taylor , A.S. Abe
      Development within the cleidoic egg of birds and reptiles presents the embryo with the problem of accumulation of wastes from nitrogen metabolism. Ammonia derived from protein catabolism is converted into the less toxic product urea or relatively insoluble uric acid. The pattern of nitrogen excretion of the green iguana, Iguana iguana, was determined during embryonic development using samples from allantoic fluid and from the whole homogenized egg, and in hatchlings and adults using samples of blood plasma. Urea was the major excretory product over the course of embryonic development. It was found in higher concentrations in the allantoic sac, suggesting that there is a mechanism present on the allantoic membrane enabling the concentration of urea. The newly hatched iguana still produced urea while adults produced uric acid. The time course of this shift in the type of nitrogen waste was not determined but the change is likely to be related to the water relations associated with the terrestrial habit of the adult. The green iguana produces parchment-shelled eggs that double in mass during incubation due to water absorption; the eggs also accumulate 0.02mM of urea, representing 82% of the total measured nitrogenous residues that accumulate inside the allantois. The increase in egg mass and urea concentration became significant after 55days of incubation then were unchanged until hatching.

      PubDate: 2015-06-20T16:50:39Z
  • Vocal and territorial behavior in the Smith frog (Hypsiboas faber):
           Relationships with plasma levels of corticosterone and testosterone
    • Abstract: Publication date: November 2012
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 163, Issues 3–4
      Author(s): Vania Regina de Assis , Carlos Arturo Navas , Mary T. Mendonça , Fernando Ribeiro Gomes
      The possible trade-off between the roles of glucocorticoids as facilitators of energy substrate mobilization and neural inhibitors of sexual behavior during breeding season is under debate. We studied the relationship between calling and territorial behavior with plasma levels of corticosterone (CORT) and plasma levels of testosterone (T) across the breeding season of Hypsiboas faber, a large and territorial Neotropical treefrog. We investigated these relationships through focal observations of males calling naturally, followed by blood sampling for hormonal radioimmunoassay. We additionally used an experimental approach, which consisted of broadcasting recorded advertisement calls for 10min to simulate an invasion in the territory of the focal subjects, followed by behavioral observation and blood sampling for hormonal radioimmunoassay. Results showed a pattern of co-variation between CORT and T across the breeding season. Furthermore, individual variation in CORT and T was related to different aspects of behavior: individuals with higher CORT showed higher calling rates, and individuals with higher steroid levels, mainly T, showed higher responsivity to social stimulation by other males in the chorus. Experimental simulation of territorial intrusion by using playback of advertisement calls of this species did not elicit consistent changes in agonistic behavior and CORT, but decreased T in focal males.

      PubDate: 2015-06-20T16:50:39Z
  • Glutathione status and antioxidant enzymes in a crocodilian species from
           the swamps of the Brazilian Pantanal
    • Abstract: Publication date: October 2012
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 163, Issue 2
      Author(s): Marcelo Hermes-Lima , Cecília Carreiro , Daniel C. Moreira , Cássia Polcheira , Daniel P. Machado , Élida G. Campos
      In a previous study oxidative damage markers – lipid peroxidation and protein oxidation – were determined in organs of wild Caiman yacare captured in winter-2001 and summer-2002 at various developmental stages. An increase in oxidative damage occurred in the hatchling-juvenile transition (but not in the juvenile-adult transition) and winter–summer transition (in juveniles), suggesting that oxidative stress is associated with development and season. Herein the effect of development and season on glutathione (GSH) metabolism and the effect of development on the activity of antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase and glutathione S-transferase) and glucose 6-phosphate dehydrogenase were analyzed. The ratio GSSG:GSH-eq increased in lung, liver, kidney and brain by 1.8- to 4-fold in the embryo/hatchling to juvenile transition. No changes occurred in juvenile–adult transition. GSSG:GSH-eq across seasons was significantly elevated in summer. Total-glutathione content was mostly stable in various organs; in liver it increased in the embryo–juvenile transition. Enzyme activities were only determined in summer-animals (embryos, hatchlings and juveniles). For most antioxidant enzymes, activities increased from embryo/hatchling to juvenile in liver and Kidney. In lung, there was an inverse trend for enzyme activities and total glutathione content. Thus, increased metabolic rates during early caiman growth – in embryo–juvenile transition – appears to be related to redox imbalance as suggested by increased GSSG:GSH-eq and activation of antioxidant defenses. Differences in oxidative stress across seasons were related with summer–winter nocturnal temperatures. These results, as a whole, were interpreted in the context of ecological biochemistry.

      PubDate: 2015-06-20T16:50:39Z
  • Effect of starvation and refeeding on amino acid metabolism in muscle of
           crab Neohelice granulata previously fed protein- or carbohydrate-rich
    • Abstract: Publication date: January 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 164, Issue 1
      Author(s): Ricardo Pellegrino , Tiago Leal Martins , Charles Budaszewski Pinto , Vanessa Schein , Luiz Carlos Kucharski , Roselis Silveira Martins Da Silva
      The present study assesses the effects of starvation and refeeding on 1-[14C]-methyl aminoisobutyric acid (14C-MeAIB) uptake, 14C-total lipids, 14CO2 production from 14C-glycine, 14C-protein synthesis from 14C-leucine and Na+–K+-ATPase activity in jaw muscle of Neohelice granulata previously maintained on a carbohydrate-rich (HC) or high-protein (HP) diet. In N. granulata the metabolic adjustments during starvation and refeeding use different pathways according to the composition of the diet previously offered to the crabs. During starvation, 14CO2 production from 14C-glycine, and 14C-protein synthesis from 14C-leucine were reduced in HC-fed crabs. In crabs maintained on the HP or HC diet, 14C-total lipid synthesis increased after 15days of starvation. In crabs fed HP diet, 14C-MeAIB uptake and Na+–K+-ATPase activity decreased in refeeding state. In crabs refeeding HC diet, 14C-MeAIB uptake and 14CO2 production decreased during the refeeding. In contrast, the 14C-protein synthesis increased after 120h of refeeding. In both dietary groups, 14C-total lipid synthesis increased during refeeding. Changes in the carbon amino acid flux between different metabolic pathways in muscle are among the strategies used by this crab to face starvation and refeeding. Protein or carbohydrate levels in the diet administered to this crab modulate the carbon flux between the different metabolic pathways.

      PubDate: 2015-06-20T16:50:39Z
  • Role of brain nitric oxide in the cardiovascular control of bullfrogs
    • Abstract: Publication date: June 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 165, Issue 2
      Author(s): Lucas A. Zena , Luciane H. Gargaglioni , Kênia C. Bícego
      The goal of the present study was to determine if nitric oxide (NO) acting on the brain of bullfrog (Lithobates catesbeianus) is involved in arterial pressure and heart rate (HR) control by influencing sympathetic activity. We investigated the effect of intracerebroventricular injections of l-NMMA (a nonselective NO synthase inhibitor) on mean arterial blood pressure (MAP), HR and cutaneous vascular conductance (CVC) of pelvic skin after intravenous injection of α or β adrenergic blockers, prazosin or sotalol, respectively. Arterial pressure was directly measured by a telemetry sensor inserted in the aortic arch of animals. l-NMMA increased MAP, but did not change HR. This hypertensive response was inhibited by the pre-treatment with prazosin, but accentuated by sotalol. The effect of l-NMMA on MAP was also inhibited by i.v. injections of the ganglionic blocker, hexamethonium. Thus, NO acting on the brain of bullfrog seems to present a hypotensive effect influencing the sympathetic activity dependent on α and β adrenergic receptors in the periphery.

      PubDate: 2015-06-20T16:50:39Z
  • Direct relationship between osmotic and ionic conforming behavior and
           tissue water regulatory capacity in echinoids
    • Abstract: Publication date: March 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 164, Issue 3
      Author(s): Ivonete A. Santos , Giovanna C. Castellano , Carolina A. Freire
      Echinoderms are considered marine osmoconforming invertebrates. However, many are intertidal or live next to estuaries, tolerating salinity changes and showing extracellular gradients to dilute seawater. Three species of echinoids – Lytechinus variegatus, which can occur next to estuarine areas, the rocky intertidal Echinometra lucunter, and the mostly subtidal Arbacia lixula – were submitted to a protocol of stepwise (rate of 2–3psu/h) dilution, down to 15psu, or concentration, up to 45psu, of control seawater (35psu). Coelomic fluid samples were obtained every hour. The seawater dilution experiment lasted 8h, while the seawater concentration experiment lasted 6h. Significant gradients (40–90% above value in 15psu seawater) for osmolality, sodium, magnesium, and potassium were shown by L. variegatus and E. lucunter. A. lixula showed the smallest gradients, displaying the strongest conforming behavior. The esophagus of the three species was challenged in vitro with 20 and 50% osmotic shocks (hypo- and hyperosmotic). A. lixula, the most “conforming” species, showed the highest capacity to avoid swelling of its tissues upon the −50% hyposmotic shock, and was also the species less affected by salinity changes concerning the observation of spines and ambulacral feet movement in the whole-animal experiments. Thus, the most conforming species (A. lixula) displayed the highest capacity to regulate tissue water/volume, and was also the most euryhaline among the three studied species. In addition, tissues from all three species swelled much more than they shrank under osmotic shocks of same magnitude. This distinct trend to gain water, despite the capacity to hold some gradients upon seawater dilution, helps to explain why echinoderms cannot be fully estuarine, or ever enter fresh water.

      PubDate: 2015-06-20T16:50:39Z
  • How ubiquitous is endothelial NOS'
    • Abstract: Publication date: September 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 166, Issue 1
      Author(s): Fahima Syeda , David Hauton , Steven Young , Stuart Egginton
      The ability to regulate vascular tone is an essential cardiovascular control mechanism, with nitric oxide (NO) assumed to be a ubiquitous smooth muscle relaxant. However, the literature contains reports of vasoconstrictor, vasodilator and no response to nitroergic stimulation in non-mammalian vertebrates. We examined functional (branchial artery myography), structural (immunohistochemistry of skeletal muscle), proteomic (Western analysis) and genomic (RT-PCR, sequence orthologues, syntenic analysis) evidence for endothelial NO synthase (NOS3) in model and non-model fish species. A variety of nitrodilators failed to elicit any changes in vascular tone, although a dilatation to exogenous cyclic GMP was noted. NOS3 antibody staining does not localise to endothelial markers in cryosections, and gives rise to non-specific staining of Western blots. Abundant NOS2 mRNA was found in all species but NOS3 was not found in any fish, while putative orthologues are not flanked by similar genes to NOS3 in humans. We conclude that NOS3 does not exist in fish, and that previous reports of its presence may reflect use of antibodies raised against mammalian epitopes.

      PubDate: 2015-06-20T16:50:39Z
  • Cardiac hypertrophy and structural and metabolic remodeling related to
           seasonal dormancy in the first annual cycle in tegu lizards
    • Abstract: Publication date: July 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 165, Issue 3
      Author(s): Lilian Cristina da Silveira , Lucas Francisco R. do Nascimento , Alison Colquhoun , Augusto S. Abe , Silvia Cristina R. de Souza
      Morpho-functional adjustments in the heart of juvenile tegu lizards (Tupinambis merianae) were analyzed at distinct seasonal periods to investigate how the demands of growth and of energy saving are reconciled during the first annual cycle. The relative ventricular mass (Mv) was 31% and 69% larger in late autumn and winter dormancy, respectively, compared to early autumn. This effect did not persist during unfed arousal, suggesting that protein accumulates in the heart during hypometabolism and is degraded on arousal. Both the hypertrophy and the atrophy were disproportionate in the largest individuals. In contrast, Mv was smaller in lizards that were starved during spring activity compared to fed lizards, this effect being larger in smaller individuals. In late autumn and winter dormancy the spongy myocardium had 8% of the section area covered by lacunary spaces, which expanded after food intake during arousal and reached 29% in spring activity together with higher density of cardiomyocytes. Total and soluble proteins per mass unity were unchanged, and maximum activities of selected enzymes suggest sustained glycolytic and aerobic capacities during hypometabolism. Results indicate that important structural adjustments occur in the heart in anticipation of dormancy, and that the protein balance in the tissue is maintained at winter temperatures ~17°C.

      PubDate: 2015-06-20T16:50:39Z
  • Some euryhalinity may be more common than expected in marine
           elasmobranchs: The example of the South American skate Zapteryx
           brevirostris (Elasmobranchii, Rajiformes, Rhinobatidae)
    • Abstract: Publication date: September 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 166, Issue 1
      Author(s): Natascha Wosnick , Carolina A. Freire
      Elasmobranchs are essentially marine, but ~15% of the species occur in brackish or freshwater. The Brazilian marine coastal skate Zapteryx brevirostris, non-reported in nearby estuaries, was submitted to 35, 25, 15, and 5 psu, for 6 or 12h (n=6). Plasma was assayed for osmolality, urea, and ions (Na+, Cl−, K+, Mg2+). Muscle water content was determined, and the rectal gland, kidney and gills were removed for carbonic anhydrase (CA) and Na+,K+-ATPase (NKA) activities. The skate survived to all treatments. Plasma osmolality and urea levels decreased respectively by 27% and 38% after 12h in 5 psu (with respect to levels when in seawater), but plasma Na+, Cl−, and Mg2+ were well regulated. Plasma K+ showed some conformation after 12h. Muscle hydration was maintained. Branchial CA and NKA did not respond to salinity. Rectal gland NKA decreased upon seawater dilution, while renal NKA increased. This skate was shown to be partially euryhaline. The analysis of plasma urea of elasmobranchs in brackish and freshwater versus salinity and time—allied to the widespread occurrence of some euryhalinity in the group—led us to revisit the hypothesis of a brackish water habitat for elasmobranch ancestors.

      PubDate: 2015-06-20T16:50:39Z
  • Branchial O2 chemoreceptors in Nile tilapia Oreochromis niloticus: Control
           of cardiorespiratory function in response to hypoxia
    • Abstract: Publication date: September 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 166, Issue 1
      Author(s): Vivian M. Zeraik , Thiago C. Belão , Luiz Henrique Florindo , Ana L. Kalinin , F. Tadeu Rantin
      This study examined the distribution and orientation of gill O2 chemoreceptors in Oreochromis niloticus and their role in cardiorespiratory responses to graded hypoxia. Intact fish, and a group with the first gill arch excised (operated), were submitted to graded hypoxia and their cardiorespiratory responses (oxygen uptake - V ˙ O 2 , breathing frequency - f R, ventilatory stroke volume - V T, gill ventilation - V ˙ G , O2 extraction from the ventilatory current - EO2, and heart rate - f H) were compared. Their responses to bolus injections of NaCN into the bloodstream (internal) or ventilatory water stream (external) were also determined. The V ˙ O 2 of operated fish was significantly lower at the deepest levels of hypoxia. Neither reflex bradycardia nor ventilatory responses were completely abolished by bilateral excision of the first gill arch. EO2 of the operated group was consistently lower than the intact group. The responses to internal and external NaCN included transient decreases in f H and increases in f R and V amp (ventilation amplitude). These cardiorespiratory responses were attenuated but not abolished in the operated group, indicating that chemoreceptors are not restricted to the first gill arch, and are sensitive to oxygen levels in both blood and water.

      PubDate: 2015-06-20T16:50:39Z
  • Calcium transport in gill cells of Ucides cordatus, a mangrove crab living
           in variable salinity environments
    • Abstract: Publication date: October 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 166, Issue 2
      Author(s): V.P. Leite , F.P. Zanotto
      Crustaceans show discontinuous growth and have been used as a model system for studying cellular mechanisms of calcium transport, which is the main mineral found in their exoskeleton. Ucides cordatus, a mangrove crab, is naturally exposed to fluctuations in calcium and salinity. To study calcium transport in this species during isosmotic conditions, dissociated gill cells were marked with fluo-3 and intracellular Ca2+ change was followed by adding extracellular Ca2+ as CaCl2 (0, 0.1, 0.25, 0.50, 1.0 and 5mM), together with different inhibitors. For control gill cells, Ca2+ transport followed Michaelis–Menten kinetics with Vmax =0.137±0.001 ∆Ca2+i (μM×22.104 cells−1 ×180s−1; N=4; r2 =0.99); Km =0.989±0.027mM. The use of different inhibitors for gill cells showed that amiloride (Na+/Ca2+ exchange inhibitor) inhibited 80% of Ca2+ transport in gill cells (Vmax). KB-R, an inhibitor of Ca influx in vertebrates, similarly caused a decrease in Ca2+ transport and verapamil (Ca2+ channel inhibitor) had no effect on Ca2+ transport, while nifedipine (another Ca2+ channel inhibitor) caused a 20% decrease in Ca2+ affinity compared to control values. Ouabain, on the other hand, caused no change in Ca2+ transport, while vanadate increased the concentration of intracellular calcium through inhibition of Ca2+ efflux probably through the plasma membrane Ca2+-ATPase. Results show that transport kinetics for Ca2+ in these crabs under isosmotic conditions is lower compared to a hyper-regulator freshwater crab Dilocarcinus pagei studied earlier using fluorescent Ca2+ probes. These kinds of studies will help understanding the comparative mechanisms underlying the evolution of Ca transport in crabs living in different environments.

      PubDate: 2015-06-20T16:50:39Z
  • Effect of low pH exposure on Na+ regulation in two cichlid fish species of
           the Amazon
    • Abstract: Publication date: November 2013
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 166, Issue 3
      Author(s): Rafael M. Duarte , Marcio S. Ferreira , Chris M. Wood , Adalberto L. Val
      We evaluated the effects of acute exposure to low pH on Na+ regulation in two Amazon cichlids collected from natural ion-poor “blackwaters”, angelfish (Pterophyllum scalare) and discus (Symphysodon discus). Na+ uptake kinetic parameters, unidirectional Na+ fluxes, and net Cl− fluxes were determined at pH6.0 and 3.6. At pH6.0, both species presented low unidirectional Na+ flux rates, with kinetics showing a relatively low affinity for Na+ (angelfish Km =79, discus Km =268μmolL−1), with similar maximum transport capacities (Jmax ~535nmolg−1 h−1). Overall, there appeared to be high sensitivity to inhibition by low pH, yet low intrinsic branchial permeability limiting diffusive ion effluxes, resulting in relatively low net loss rates of Na+, the same strategy as seen previously in other blackwater cichlids, and very different from the strategy of blackwater characids. At low pH, Na+ uptake in angelfish was inhibited competitively (increased Km=166μmolL−1) and non-competitively (decreased Jmax =106nmolg−1 h−1), whereas in discus, only a decrease in Jmax (112nmolg−1 h−1) was statistically significant. An acute reduction in H+-ATPase activity, but not in Na+/K+-ATPase activity, in the gills of angelfish suggests a possible mechanism for this non-competitive inhibition at low pH. Discus fish were more tolerant to low pH than angelfish, as seen by lesser effects of exposure to pH3.6 on unidirectional Na+ uptake and efflux rates and net Na+ and Cl− loss rates. Overall, discus are better than angelfish in maintaining ionic balance under acidic, ion-poor conditions.

      PubDate: 2015-06-20T16:50:39Z
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