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  Subjects -> BIOLOGY (Total: 2835 journals)
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BIOCHEMISTRY (212 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: 193)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 11)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 7)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 9)
Advances in Biological Chemistry     Open Access   (Followers: 5)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 8)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
African Journal of Biochemistry Research     Open Access   (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: 85)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Polymer Science     Open Access   (Followers: 20)
Amino Acids     Hybrid Journal   (Followers: 6)
Analytical Biochemistry     Hybrid Journal   (Followers: 94)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 32)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 17)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 8)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 10)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access   (Followers: 2)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 3)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 15)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 5)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 9)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 20)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 4)
Biochemistry     Full-text available via subscription   (Followers: 156)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 1)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 9)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 18)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 6)
Biochimie     Hybrid Journal   (Followers: 5)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 14)
BioDrugs     Full-text available via subscription   (Followers: 7)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofuels     Hybrid Journal   (Followers: 9)
Biogeochemistry     Hybrid Journal   (Followers: 9)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 11)
Biomaterials Research     Open Access  
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 7)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 19)
BMC Biochemistry     Open Access   (Followers: 12)
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  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 24)
Chemical Engineering Journal     Hybrid Journal   (Followers: 23)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 2)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 17)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
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: 10)
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)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)

        1 2 3     

Journal Cover   Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [3 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2800 journals]
  • Embryonic water uptake during pregnancy is stage- and fecundity-dependent
           in the snake Vipera aspis
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Olivier Lourdais, Sophie Lorioux, Andréaz Dupoué, Christian Wright, Dale F. DeNardo
      Water is a crucial resource that can profoundly impact the biology of terrestrial organisms. Early life stages are particularly sensitive to hydric constraints because water uptake is an important component of embryonic development. While amniotic eggs constitute a key innovation to terrestrial life, many vertebrates are viviparous wherein the mother must be the source of water for her developing embryos. Since most viviparous squamates are lecithotrophic (i.e., energy is supplied to the offspring as yolk deposited into pre-ovulated follicles), water is the predominant resource allocated from the mother to the offspring during development. Contrary to energy that can be stored (e.g., as fat reserves), water typically cannot be acquired in advance. Therefore, the embryos' need for water can impose significant constraints on the pregnant female. We detailed water flux during pregnancy in a viviparous snake, the aspic viper (Vipera aspis). We found that embryonic water uptake occurred mostly during the second half of pregnancy—a period dominated by somatic growth. We also found that, somewhat unexpectedly, changes in female plasma osmolality were negatively related to fecundity. This latter result suggests that water consumption by the female is especially important for large litter sizes, and thus may suggest an important sensitivity of reproductive females to environmental water availability.


      PubDate: 2015-08-28T07:15:36Z
       
  • The small heat shock protein, HSP30, is associated with aggresome-like
           inclusion bodies in proteasomal inhibitor-, arsenite-, and cadmium-treated
           Xenopus kidney cells
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Saad Khan, Imran Khamis, John J. Heikkila
      In the present study, treatment of Xenopus laevis A6 kidney epithelial cells with the proteasomal inhibitor, MG132, or the environmental toxicants, sodium arsenite or cadmium chloride, induced the accumulation of the small heat shock protein, HSP30, in total and in both soluble and insoluble protein fractions. Immunocytochemical analysis revealed the presence of relatively large HSP30 structures primarily in the perinuclear region of the cytoplasm. All three of the stressors promoted the formation of aggresome-like inclusion bodies as determined by immunocytochemistry and laser scanning confocal microscopy using a ProteoStat aggresome dye and additional aggresomal markers, namely, anti-γ-tubulin and anti-vimentin antibodies. Further analysis revealed that HSP30 co-localized with these aggresome-like inclusion bodies. In most cells, HSP30 was found to envelope or occur within these structures. Finally, we show that treatment of cells with withaferin A, a steroidal lactone with anti-inflammatory, anti-tumor, and proteasomal inhibitor properties, also induced HSP30 accumulation that co-localized with aggresome-like inclusion bodies. It is possible that proteasomal inhibitor or metal/metalloid-induced formation of aggresome-like inclusion bodies may sequester toxic protein aggregates until they can be degraded. While the role of HSP30 in these aggresome-like structures is not known, it is possible that they may be involved in various aspects of aggresome-like inclusion body formation or transport.


      PubDate: 2015-08-28T07:15:36Z
       
  • Delayed access of low body weight-selected chicks to food at hatch is
           associated with up-regulated pancreatic glucagon and glucose transporter
           gene expression
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Grace A. Parker, Lindsay H. Sumners, Xiaoling Zhao, Christa F. Honaker, Paul B. Siegel, Mark A. Cline, Elizabeth R. Gilbert
      Chickens selected for low (LWS) and high (HWS) juvenile body weight (BW) for 55 generations differ in BW by 10-fold at selection age. High (HWR) and low (LWR) body weight-relaxed lines have been random-bred since the 46th generation. Our objective was to evaluate the developmental and nutritional regulation of pancreatic mRNA abundance of pancreatic and duodenal homeobox 1 (PDX1), preproinsulin (PPI), preproglucagon (PPG), and glucose transporter 2 (GLUT2). At day of hatch (DOH) and days 1, 3, 7, and 15 (D1, 3, 7 and 15, respectively), pancreas was collected and real time PCR was performed in Experiment 1. In Experiment 2, HWS and LWS were fed or delayed access to food for 72h post-hatch, and pancreas collected at D15. There was an interaction of line and age for GLUT2 (P =0.001), PPI (P <0.0001), PPG (P =0.034), and PDX1 (P <0.0001). Expression was greater in chicks from LWR and LWS than HWR and HWS. There was an interaction of line and nutrition on PPG (P <0.0001) and GLUT2 (P =0.001) mRNA, where expression was similar among chicks that were fed but greater in LWS than HWS when chicks were delayed access to food. Thus, the first two weeks is important for maturation of pancreatic endocrine function. Long-term selection for BW is associated with differences in pancreas development, and delaying access to food at hatch may have persisting effects on glucose regulatory function.


      PubDate: 2015-08-28T07:15:36Z
       
  • Physiological and behavioral responses of the invasive amphipod,
           Dikerogammarus villosus, to ammonia
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Monika Normant-Saremba, Jochen Becker, Carola Winkelmann
      We studied the physiological and behavioral responses of the Ponto-Caspian amphipod Dikerogammarus villosus during exposure to four total ammonia concentrations (NH3 +NH4 +; Tot Amm): 0.003 (control), 0.06, 1.6, and 7.0mmol L−1 (0.042, 0.84, 22.4, and 98.0mg L−1) for a period of up to 12h at 21°C. During the transition period from the control to treatment concentration as well as during the first hour of exposure to 0.06 and 1.6mmol L−1, gammarids increased their locomotor activity, which was manifested in significantly higher routine metabolic rates compared to control conditions. At control conditions, the resting metabolic rate amounted to 0.98±0.26mW g−1 and significantly increased by 19 and 37% at 0.06 and 1.6mmol L−1, respectively. The highest examined [Tot Amm] caused a rapid and significant increase in resting metabolic rate by 37% within the first 4h of exposure before gammarids died. The exposure to elevated [Tot Amm] also resulted in a significant decreased RNA:DNA ratio and significantly higher glycogen concentrations compared to the control. We conclude that even a short exposure to Tot Amm of 0.06mmol L−1, which may occur in natural habitats, disturbs the physiology and behavior of D. villosus and leads to increased metabolic costs of the maintenance and reduced protein synthesis.


      PubDate: 2015-08-28T07:15:36Z
       
  • Broiler chicken adipose tissue dynamics during the first two weeks
           post-hatch
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Shiping Bai, Guoqing Wang, Wei Zhang, Shuai Zhang, Brittany Breon Rice, Mark Andrew Cline, Elizabeth Ruth Gilbert
      Selection of broiler chickens for growth has led to increased adipose tissue accretion. To investigate the post-hatch development of adipose tissue, the abdominal, clavicular, and subcutaneous adipose tissue depots were collected from broiler chicks at 4 and 14days post-hatch. As a percent of body weight, abdominal fat increased (P <0.001) with age. At day 4, clavicular and subcutaneous fat depots were heavier (P <0.003) than abdominal fat whereas at day 14, abdominal and clavicular weighed more (P <0.003) than subcutaneous fat. Adipocyte area and diameter were greater in clavicular and subcutaneous than abdominal fat at 4 and 14days post-hatch (P <0.001). Glycerol-3-phosphate dehydrogenase (G3PDH) activity increased (P <0.001) in all depots from day 4 to 14, and at both ages was greatest in subcutaneous, intermediate in clavicular, and lowest in abdominal fat (P <0.05). In clavicular fat, peroxisome proliferator-activated receptor-γ (PPARγ), CCAAT/enhancer binding protein (CEBP)α, CEBPβ, fatty acid synthase (FASN), fatty acid binding protein 4 (FABP4), lipoprotein lipase (LPL), neuropeptide Y (NPY), and NPY receptor 5 (NPYR5) mRNA increased and NPYR2 mRNA decreased from day 4 to 14 (P <0.001). Thus, there are site-specific differences in broiler chick adipose development, with larger adipocytes and greater G3PDH activity in subcutaneous fat at day 4, more rapid growth of abdominal fat, and clavicular fat intermediate for most traits. Adipose tissue expansion was accompanied by changes in gene expression of adipose-associated factors.


      PubDate: 2015-08-28T07:15:36Z
       
  • Claudins in a primary cultured puffer fish (Tetraodon nigroviridis) gill
           epithelium model alter in response to acute seawater exposure
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Phuong Bui, Scott P. Kelly
      Gill epithelium permeability and qualitative/quantitative aspects of gill claudin (cldn) tight junction (TJ) protein transcriptomics were examined with a primary cultured model gill epithelium developed using euryhaline puffer fish (Tetraodon nigroviridis) gills. The model was prepared using seawater-acclimated fish gills and was cultured on permeable cell culture filter supports. The model is composed of 1–2 confluent layers of gill pavement cells (PVCs), with the outer layer exhibiting prominent apical surface microridges and TJs between adjacent cells. During development of electrophysiological characteristics, the model exhibits a sigmoidal increase in transpithelial resistance (TER) and plateaus around 30kΩcm2. At this point paracellular movement of [3H]polyethylene glycol (PEG) 4000 was low at ~1.75cms−1 ×10−7. When exposed to apical seawater (SW) epithelia exhibit a marked decrease in TER while PEG flux remained unchanged for at least 6h. In association with this, transcript encoding cldn TJ proteins cldn3c, -23b, -27a, -27c, -32a and -33b increased during the first 6h while cldn11a decreased. This suggests that these proteins are involved in maintaining barrier properties between gill PVCs of SW fishes. Gill cldn mRNA abundance also altered 6 and 12h following abrupt SW exposure of puffer fish, but in a manner that differed qualitatively and quantitatively from the cultured model. This most likely reflects the cellular heterogeneity of whole tissue and/or the contribution of the endocrine system in intact fish. The current study provides insight into the physiological and transcriptomic response of euryhaline fish gill cells to a hyperosmotic environment.


      PubDate: 2015-08-16T05:29:23Z
       
  • Effect of temperature on oxidative stress, antioxidant levels and
           uncoupling protein expression in striped hamsters
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Si-Si Zhou, Li-Li Cao, Wei-Dong Xu, Jing Cao, Zhi-Jun Zhao
      According to the rate of living-free radical hypothesis, higher metabolic rates should increase reactive oxygen species (ROS) production. However, the “uncoupling to survive” hypothesis postulates that uncoupling proteins (UCPs) can decrease ROS production by lowering the potential of the inner mitochondrial membrane, in which case the correlation between metabolic rate and ROS levels would be a negative rather than positive. In this study, we examined energy intake, oxidative stress levels, antioxidant activity and the expression of UCPs in brown adipose tissue (BAT), and in the liver, heart, skeletal muscle and brain, of striped hamsters (Cricetulus barabensis) acclimated to either 5°C or 32.5°C. The energy intake of hamsters acclimated to 5°C increased by 70.7%, whereas the energy intake of hamsters acclimated to 32.5°C decreased by 31.3%, relative to hamsters kept at room temperature (21°C) (P <0.05). Malonadialdehyde (MDA) levels, total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-PX) activity in BAT significantly decreased in 5°C group, but increased in 32.5°C group, relative to the 21°C group. Neither ROS levels (i.e. H2O2 levels), nor antioxidants in skeletal muscle, liver, heart or brain tissue, were affected by temperature. UCP1 expression in BAT was significantly up-regulated in 5°C group, but down-regulated in 32.5°C group, relative to the 21°C group. UCP3 expression of skeletal muscle was also up-regulated significantly in hamsters acclimated to 5°C. These results suggest that the relationship between ROS levels and metabolic rate was negative, rather than positive. UCP1 expression in BAT may have played a role in lowering ROS levels.


      PubDate: 2015-08-16T05:29:23Z
       
  • Structural lipid changes and Na+/K+-ATPase activity of gill cells'
           basolateral membranes during saltwater acclimation in sea lamprey
           (Petromyzon marinus, L.) juveniles
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Maria João Lança, Maria Machado, Ana Filipa Ferreira, Bernardo Ruivo Quintella, Pedro Raposo de Almeida
      Seawater acclimation is a critical period for anadromous species and a process yet to be understood in lampreys. Considering that changes in lipid composition of the gill cells' basolateral membranes may disrupt the major transporter Na+K+-ATPase, the goal of this study was to detect changes at this level during juvenile sea lamprey seawater acclimation. The results showed that saltwater acclimation has a direct effect on the fatty acid composition of gill cells basolateral membrane's phospholipids. When held in full-strength seawater, the fatty acid profile of basolateral membrane's phospholipids suffered a restructure by increasing either saturation or the ratio between oleic acid and eicosapentaenoic acid. Simultaneously, the activity of Na+K+-ATPase revealed a significant and positive correlation with basolateral membrane's cholesterol content in the presence of highest salinity. Our results pointed out for lipid adjustments involving the functional transporter present on the gill cell basolateral membranes to ensure the role played by branchial Na+K+-ATPase in ion transport during saltwater acclimation process. The responses observed contributed to the strategy adopted by gill cell's basolateral membranes to compensate for osmotic and ionic stressors, to ensure the success of the process of seawater acclimation associated with the downstream trophic migration of juvenile sea lamprey.


      PubDate: 2015-08-16T05:29:23Z
       
  • Digestive enzyme activities in the guts of bonnethead sharks (Sphyrna
           tiburo) provide insight into their digestive strategy and evidence for
           microbial digestion in their hindguts
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Parth Jhaveri, Yannis P. Papastamatiou, Donovan P. German
      Few investigations have studied digestive enzyme activities in the alimentary tracts of sharks to gain insight into how these organisms digest their meals. In this study, we examined the activity levels of proteases, carbohydrases, and lipase in the pancreas, and along the anterior intestine, spiral intestine, and colon of the bonnethead shark, Sphyrna tiburo. We then interpreted our data in the context of a rate-yield continuum to discern this shark's digestive strategy. Our data show anticipated decreasing patterns in the activities of pancreatic enzymes moving posteriorly along the gut, but also show mid spiral intestine peaks in aminopeptidase and lipase activities, which support the spiral intestine as the main site of absorption in bonnetheads. Interestingly, we observed spikes in the activity levels of N-acetyl-β-d-glucosaminidase and β-glucosidase in the bonnethead colon, and these chitin- and cellulose-degrading enzymes, respectively, are likely of microbial origin in this distal gut region. Taken in the context of intake and relatively long transit times of food through the gut, the colonic spikes in N-acetyl-β-d-glucosaminidase and β-glucosidase activities suggest that bonnetheads take a yield-maximizing strategy to the digestive process, with some reliance on microbial digestion in their hindguts. This is one of the first studies to examine digestive enzyme activities along the gut of any shark, and importantly, the data match with previous observations that sharks take an extended time to digest their meals (consistent with a yield-maximizing digestive strategy) and that the spiral intestine is the primary site of absorption in sharks.


      PubDate: 2015-08-16T05:29:23Z
       
  • Cortisol affects metabolic and ionoregulatory responses to a different
           extent depending on feeding ration in common carp, Cyprinus carpio
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Hon Jung Liew, Angela Fazio, Caterina Faggio, Ronny Blust, Gudrun De Boeck
      Interacting effects of feeding and stress on corticoid responses in fish were investigated in common carp fed 3.0% or 0.5% body mass (BM) which received no implant, a sham or a cortisol implant (250mg/kg BM) throughout a 168hour post-implant period (168h-PI). At 12h-PI, cortisol implants elevated plasma cortisol, glucose and lactate. Plasma osmolality and ions remained stable, but cortisol increased gill and kidney Na+/K+ ATPase (NKA) and H+ ATPase activities. Gill NKA activities were higher at 3%-BM, whereas kidney H+ ATPase activity was greater at 0.5%-BM. Cortisol induced liver protein mobilization and repartitioned liver and muscle glycogen. At 3%-BM, this did not increase plasma ammonia, reflecting improved excretion efficiency concomitant with upregulation of Rhesus glycoprotein Rhcg-1 in gill. Responses in glucocorticoid receptors (GR1/GR2) and mineralocorticoid receptor (MR) to cortisol elevation were most prominent in kidney with increased expression of all receptors at 24h-PI at 0.5%-BM, but only GR2 and MR at 0.5%-BM. In the liver, upregulation of all receptors occurred at 24h-PI at 3%-BM, whilst only GR2 and MR were upregulated at 0.5%-BM. In the gill, there was a limited upregulation: GR2 and MR at 72h-PI and GR1 at 168h-PI at 3%-BM but only GR2 at 72h-PI at 0.5%-BM. Thus cortisol elevation led to similar expression patterns of cortisol receptors in both feeding regimes, while feeding affected the type of receptor that was induced. Induction of corticoid receptors occurred simultaneously with increases in Rhcg-1 mRNA expression (gill) but well after NKA and H+ ATPase activities increased (gill/kidney).


      PubDate: 2015-08-11T04:36:46Z
       
  • Evaluating hypoxia-inducible factor-1α mRNA expression in a pelagic
           fish, Pacific herring Clupea pallasii, as a biomarker for hypoxia exposure
           
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Halley E. Froehlich, Steven B. Roberts, Timothy E. Essington
      Hypoxia [dissolved oxygen (DO)<2mgL−1] is a major environmental perturbation for many aquatic ecosystems, particularly highly productive estuaries. Most research attention and understanding about the impacts of hypoxia on estuarine species has focused on the benthos, where hypoxia is most common. Although the pelagic zone is also susceptible to the effects of hypoxia, the biological interactions and consequences are not as well understood in marine environments because documenting exposure or avoidance of hypoxia is often difficult. Physiological biomarkers may provide a way to gain more detailed spatiotemporal information regarding species' exposure to hypoxia. Here, we identified and tested a hypoxia-specific responsive gene, hypoxia-inducible factor-1α (hif-1α), to evaluate its potential as a biomarker for hypoxia exposure in Pacific herring (Clupea pallasii). We conducted controlled laboratory experiments to establish the level of hepatic hif-1α elevated gene expression (>1 sd normoxic mean), exposure amplification (≥2hours), reduction rate (ca. 24hours), and some evidence of a lethal hypoxic limit (ca. 2mgL−1, ≥4hours). We then used these findings to evaluate the spatiotemporal patterns of hif-1α for Pacific herring in a seasonally hypoxia estuary, Hood Canal, Washington, USA. Although expression did not parallel the local hypoxic conditions in the estuary, herring from the more severe hypoxic year (2013) had a higher probability of having elevated mRNA levels. These patterns indicate that hepatic hif-1α levels may not be directly indicative of local DO levels for pelagic marine fish, but rather provide insight into hypoxia exposure over broader scales.


      PubDate: 2015-08-11T04:36:46Z
       
  • Surviving in a semi-marine habitat: Dietary salt exposure and salt
           secretion of a New Zealand intertidal skink
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Jordi Janssen, David R. Towns, Mark Duxbury, Ignas M.A. Heitkönig
      Species that inhabit marine and intertidal ecosystems face osmoregulatory challenges, risking dehydration and increased ion concentrations in the body. Lizards need to either tolerate or regulate these increased ion concentrations. In this study, we aim to understand how Suter's skink (Oligosoma suteri), an intertidal skink restricted to shoreline habitats, is able to cope with the physiological stress of living in an extreme salt environment. We determined the diet, prey species' salt content, and nasal and cloacal salt excretion on Rangitoto and Motutapu Islands in northern New Zealand, where the skinks have contrasting access to terrestrial invertebrates. Analysis of stable isotopes suggests inter- and intra-population variability in Suter's skink diets. Intertidal invertebrates under washed up seaweed appear to compose a major part of the diet of the Rangitoto population, while the Motutapu population showed evidence for a mixed diet of terrestrial and intertidal invertebrates. Sodium content of prey species decreased with an increasing distance from the seawater. Field secretion of cations through nasal glands consisted primarily of Na+, which is consistent with other marine and intertidal species. Sodium was also the primary cation in urine. In contrast, fecal cations consisted primarily of K+. This first study into the salt secretion of an intertidal skink species provides evidence of Suter's skink's plasticity in secreting excess ions through nasal salt glands. This likely enables it to deal with the challenges of living in a semi-marine habitat.


      PubDate: 2015-08-07T04:11:43Z
       
  • Editorial Board
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188




      PubDate: 2015-08-07T04:11:43Z
       
  • Molecular reproductive characteristics of the reef coral Pocillopora
           damicornis
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Luc R.A. Rougée, Robert H. Richmond, Abby C. Collier
      Coral reefs are an indispensible worldwide resource, accounting for billions of dollars in cultural, economic, and ecological services. An understanding of coral reproduction is essential to determining the effects of environmental stressors on coral reef ecosystems and their persistence into the future. Here, we describe the presence of and changes in steroidal hormones along with associated steroidogenic and steroid removal enzymes during the reproductive cycle of the brooding, pan-Pacific, hermaphroditic coral, Pocillopora damicornis. Detectable levels of 17β-estradiol, estrone, progesterone and testosterone were consistently detected over two consecutive lunar reproductive cycles in coral tissue. Intra-colony variation in steroid hormone levels ranged between 1.5- and 2.2-fold and were not statistically different. Activities of the steroidogenic enzymes 3β-hydroxysteroid dehydrogenase and cytochrome P450 (CYP) 17 dehydrogenase were detectable and did not fluctuate over the reproductive cycle. Aromatase-like activity was detected during the lunar reproductive cycle with no significant fluctuations. Activities of regeneration enzymes did not fluctuate over the lunar cycle; however, activity of the clearance enzyme UDP-glucuronosyl transferases increased significantly (ANOVA, post hoc p <0.01) during the two weeks before and after peak larval release (planulation), suggesting that the activity of this enzyme family may be linked to the reproductive state of the coral. Sulfotransferase enzymes could not be detected. Our findings provide the first data defining normal physiological and lunar/reproductive variability in steroidal enzymes in a coral species with respect to their potential role in coral reproduction.


      PubDate: 2015-08-07T04:11:43Z
       
  • Physiological responses of the ghost shrimp Neotrypaea uncinata (Milne
           Edwards 1837) (Decapoda: Thalassinidea) to oxygen availability and
           recovery after severe environmental hypoxia
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Félix P. Leiva, Mauricio A. Urbina, Juan Pablo Cumillaf, Paulina Gebauer, Kurt Paschke
      Hypoxia is a common and widespread phenomenon in aquatic ecosystems, imposing a significant challenge for the animals that inhabit such waters. In different habitats, however, the characteristics of these hypoxic events may differ, therefore imposing different challenges. We investigated the tolerance of adult ghost shrimp Neotrypaea uncinata (an intertidal mudflat dweller) to different partial pressures of oxygen (pO2), severe hypoxia (2kPa) and recovery from hypoxia after different exposure times, mimicking the natural tidal cycle (6h and 12h). We calculated critical oxygen tension and categorize the adult ghost shrimps as oxyregulators (R value=75.27%). All physiological measurements (metabolic rate, oxyhemocyanin, hemolymph protein and lactate concentrations) were affected by exposure to low partial pressures of oxygen, but most of them recovered (with exception of metabolic rate) control values (21kPa) after 6h under normoxic conditions. Low metabolic rate, high release of hemolymphatic proteins and anaerobic metabolism are suggested as response mechanisms to overcome hypoxic events during low tide.


      PubDate: 2015-08-07T04:11:43Z
       
  • Plasticity of thermal tolerance and metabolism but not water loss in an
           invasive reed frog
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Sarah J. Davies, Melodie A. McGeoch, Susana Clusella-Trullas
      Phenotypic plasticity may buffer the selection pressures on organisms that inhabit novel or rapidly-changing environments. We investigated plasticity of thermal tolerance, energetic and water loss traits and their interaction with behaviour in a small-bodied, arboreal anuran (Hyperolius marmoratus Rapp, Hyperoliidae) undergoing rapid range expansion into the winter rainfall region of South Africa. After short-term exposure to three temperatures (acclimation treatments) commonly encountered in their historical and novel ranges, frogs exhibited a broad thermal tolerance range (mean±s.d.: 42.1±2.9°C) and higher plasticity in CTmax than in CTmin. Resting metabolic rate was lowest in cold-acclimated animals, while active metabolic rates were lowest in warm-acclimated frogs, likely reflecting compensation towards energy conservation. Evaporative water loss was not significantly altered by the acclimation treatments in either resting or active animals, indicating limited plasticity in this trait compared to metabolism. Our results suggest that plasticity of temperature limits and metabolism may benefit this species in variable environments such as those encountered in its expanded range. Lack of plasticity in water loss during resting and activity suggests that these frogs rely on their high cutaneous resistance and behavioural means to buffer climate variation. This study highlights the importance of synergistic interactions between physiology and behaviour in determining amphibian responses to temperature variation.


      PubDate: 2015-07-29T21:02:11Z
       
  • Starvation beneficially influences the liver physiology and nutrient
           metabolism in Edwardsiella tarda infected red sea bream (Pagrus major)
    • Abstract: Publication date: November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 189
      Author(s): Sipra Mohapatra, Tapas Chakraborty, Sonoko Shimizu, Shintaro Urasaki, Takahiro Matsubara, Yoshitaka Nagahama, Kohei Ohta
      Dietary compromises, especially food restrictions, possess species-specific effects on the health status and infection control in several organisms, including fish. To understand the starvation-mediated physiological responses in Edwardsiella tarda infected red sea bream, especially in the liver, we performed a 20-day starvation experiment using 4 treatment (2 fed and 2 starved) groups, namely, fed-placebo, starved-placebo, fed-infected, and starved-infected, wherein bacterial exposure was done on the 11th day. In the present study, the starved groups showed reduced hepatosomatic index and drastic depletion in glycogen storage and vacuole formation. The fed-infected fish showed significant (P<0.05) increase in catalase and superoxide dismutase activity in relation to its starved equivalent. Significant (P<0.05) alteration in glucose and energy metabolism, as evident from hexokinase and glucose-6-phosphate dehydrogenase activity, was recorded in the starved groups. Interestingly, coinciding with the liver histology, PPAR (peroxisome proliferator activated receptors) α transcription followed a time-dependent activation in starved groups while PPARγ exhibited an opposite pattern. The transcription of hepcidin 1 and transferrin, initially increased in 0dai (days after infection) starved fish but reduced significantly (P<0.05) at later stages. Two-color immunohistochemistry and subsequent cell counting showed significant increase in P63-positive cells at 0dai and 5dai but later reduced slightly at 10dai. Similar results were also obtained in the lysosomal (cathepsin D) and non-lysosomal (ubiquitin) gene transcription level. All together, our data suggest that starvation exerts multidirectional responses, which allows for better physiological adaptations during any infectious period, in red sea bream.


      PubDate: 2015-07-22T01:31:11Z
       
  • Effects of feed restriction on salinity tolerance in white sturgeon
           (Acipenser transmontanus)
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Seunghyung Lee, James G. Fadel, Liran Y. Haller, Christine E. Verhille, Nann A. Fangue, Silas S.O. Hung
      A multistressor study was conducted to investigate interactive effects of nutritional status and salinity on osmoregulation of juvenile white sturgeon. Our hypothesis was that lower nutritional status would decrease the salinity tolerance of juvenile white sturgeon. A four-week feed restriction (12.5%, 25%, 50%, 100% of optimum feeding rate: OFR defined as the rate (% body weight per day) at which growth is maximal) trial was performed, and relevant indices of nutritional status were measured. Following the trial, sturgeon were acutely exposed to various salinities (0, 8, 16, 24ppt) for 120h, and relevant osmoregulatory measurements were made at 12, 72, and 120h post-salinity exposures. The feed-restriction trial resulted in a graded nutritional response with the most feed-restricted group (12.5% OFR) showing the lowest nutritional status. The salinity exposure trial showed clear evidence that lower nutritional status decreased the salinity tolerance of juvenile white sturgeon. Increasing salinities resulted in significant alterations in osmoregulatory indices of all feeding groups; however, a significantly slower acclimatory response to 24ppt was detected in the most feed-restricted group compared to the non-feed-restricted group (100% OFR). Furthermore, evaluation of the effect of nutritional status on the relationship between osmoregulatory measurements and body size showed that there was a significant negative relationship between osmoregulatory performance and body size within the most feed-restricted group. This suggests that there is a certain body size range (200–300g based on our finding) where juvenile white sturgeon can maximize osmoregulatory capacity at a salinity of 24ppt.


      PubDate: 2015-07-18T01:26:41Z
       
  • Elucidating the roles of gut neuropeptides on channel catfish feed intake,
           glycemia, and hypothalamic NPY and POMC expression
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Julie C. Schroeter, Carlin M. Fenn, Brian C. Small
      Both intrinsic and extrinsic factors modulate food intake and glycemia in vertebrates, in part through interactions with hypothalamic neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons. The objective of this project was to elucidate the effects of ghrelin (GHRL), gastrin-releasing peptide (GRP), cholecystokinin (CCK), glucagon-like peptide (GLP), pancreatic polypeptide (PP), and peptide YY (PYY) on appetite, glycemia, and hypothalamic expression of NPY and POMC in channel catfish. Catfish were injected intraperitoneally with a single peptide at concentrations of either 0 (control), 50, 100, or 200ng/g body weight (BW), respectively. Fish were allowed to recover for 30min, and then fed to satiation over 1 h. Feed intake was determined 1h post-feeding. Catfish injected with GHRL at 50 and 100 ng/g BW and GRP at 200 ng/g BW consumed significantly (P <0.05) less feed compared to controls. A tendency (P <0.1) to suppress feed intake was also observed in the 200 ng/g BW GHRL and PP treatments. PYY, CCK, and GLP had no effects on feed intake. Glycemia was not affected by GHRL, GRP, PP, and PYY treatments, but was suppressed by CCK. A tendency toward lower plasma glucose concentrations was observed in fish administered GLP at 50ng/g BW. Hypothalamic NPY expression was highly variable and not significantly affected by treatment. POMC expression was also variable, but tended to be reduced by the highest concentration of CCK. These results provide new insight into the roles and regulation of gut neuropeptides in catfish appetite and glycemia.


      PubDate: 2015-07-18T01:26:41Z
       
  • In vitro oxygen exposure promotes maturation of the oxygen sensitive
           contraction in pre-term chicken ductus arteriosus
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Henry Greyner, Edward M. Dzialowski
      The ductus arteriosus (DA) are O2-sensitive, embryonic blood vessels that serve as a right-to-left shunt in developing avian embryos. Prior to internal pipping, the chicken DA produces a weak O2-induced contraction. During hatching, the O2-sensitivity of the avian DA vessels increases significantly. To see if we could accelerate the maturation of chicken DA O2-sensitivity, we exposed the vessel in vitro to elevated O2 (25kPa) for 3-h prior to internal pipping on day 19 of incubation. The DA initially responded to increasing O2 with a weak contraction (0.15±0.04N/m) that significantly increased in strength (0.63±0.06N/m) during 3-h 25kPa O2 exposure. A tonic influence of nitric oxide, not present at low O2, appeared during the 3-h 25kPa O2 exposure. The long-term O2-induced contraction was mediated by both L-type Ca2+ channels and internal Ca2+ stores. The Rho-kinase pathway inhibitors Y-27632 and fasudil produced significant relaxation, suggesting a role for Ca2+ sensitization in the contractile response to the 3h of elevated O2. While the day 19 DA initially exhibited an immature contractile response to O2, maturation of the pathways regulating O2-induced contraction was accelerated by exposure to 25kPa O2, producing contractions similar in magnitude to those found during the final stage of hatching. This suggests that maturation of O2-sensitivity may be accelerated in vivo by increasing arterial O2 levels.


      PubDate: 2015-07-18T01:26:41Z
       
  • Cold acclimation increases levels of some heat shock protein and sirtuin
           isoforms in threespine stickleback
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Laura E. Teigen, Julieanna I. Orczewska, Jessica McLaughlin, Kristin M. O’Brien
      Molecular chaperones [heat shock proteins (HSPs)] increase in response to rapid changes in temperatures, but long-term acclimation to cold temperature may also warrant elevations in HSPs. In fishes, cold acclimation increases mitochondrial density and oxidative stress in some tissues, which may increase demand for HSPs. We hypothesized that levels of HSPs, as well as sirtuins (SIRTs), NAD-dependent deacetylases that mediate changes in metabolism and responses to oxidative stress (including increases in HSPs), would increase during cold acclimation of threespine stickleback (Gasterosteus aculeatus). Transcript levels of hsp70, hsc70, hsp60 and hsp90-α, sirts1–4, as well as protein levels of HSP60, HSP90 and HSC70 were quantified in liver and pectoral adductor muscle of stickleback during cold acclimation from 20°C to 8°C. In liver, cold acclimation stimulated a transient increase in mRNA levels of hsp60 and hsc70. Transcript levels of sirt1 and sirt2 also increased in response to cold acclimation and remained elevated. In pectoral muscle, mRNA levels of hsp60, hsp90-α, hsc70 and sirt1 all transiently increased in response to cold acclimation, while levels of sirts2–4 remained constant or declined. Similar to transcript levels, protein levels of HSC70 increased in both liver and pectoral muscle. Levels of HSP90 also increased in liver after 4weeks at 8°C. HSP60 remained unchanged in both tissues, as did HSP90 in pectoral muscle. Our results indicate that while both HSPs and SIRTs increase in response to cold acclimation in stickleback, the response is tissue and isoform specific, likely reflecting differences in metabolism and oxidative stress.


      PubDate: 2015-07-18T01:26:41Z
       
  • Maternally derived trypsin may have multiple functions in the early
           development of turbot (Scopthalmus maximus)
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Liang Chi, Qinghua Liu, Shihong Xu, Zhizhong Xiao, Daoyuan Ma, Jun Li
      Trypsin is an important serine protease that is considered to be involved in digestion of protein in teleost fish. Nevertheless, studies on trypsin/trypsinogen in fish embryos are very limited. In this study, the trypsinogen of turbot (Scophthalmus maximus) (tTG) was identified and the expression patterns and activity of trypsinogen/trypsin were investigated. The results showed that the tTG mRNA was evenly distributed in the oocytes and was also expressed along the yolk periphery in early embryos. At later embryo stages and 1days after hatching (dph), the tTG mRNA concentrated at the alimentary tract and head. Quantitative expression analysis showed that the tTG transcripts decreased after fertilization until the gastrula stage, then increased with the embryo and larvae development. This result was also confirmed by the specific activity analysis of trypsin and in-situ-hybridization (ISH). All of the results indicated that tTG in early embryo stages was maternally derived and expressed by itself after gastrula stages. Additionally, location of tTG mRNA in embryos and larvae was investigated; we considered that trypsin may have multiple functions during the embryo development process. Based on our results regarding trypsinogen in embryos and early development, we concluded that the trypsin/trypsinogen in turbot embryos was inherited from a maternal source and we suggested that trypsin in early development has multiple functions in the process of development.


      PubDate: 2015-07-18T01:26:41Z
       
  • Renal plasticity in response to feeding in the Burmese python, Python
           molurus bivittatus
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): A.J. Esbaugh , S.M. Secor , M. Grosell
      Burmese pythons are sit-and-wait predators that are well adapted to go long periods without food, yet subsequently consume and digest single meals that can exceed their body weight. These large feeding events result in a dramatic alkaline tide that is compensated by a hypoventilatory response that normalizes plasma pH; however, little is known regarding how plasma HCO3 − is lowered in the days post-feeding. The current study demonstrated that Burmese pythons contain the cellular machinery for renal acid–base compensation and actively remodel the kidney to limit HCO3 − reabsorption in the post-feeding period. After being fed a 25% body weight meal plasma total CO2 was elevated by 1.5-fold after 1day, but returned to control concentrations by 4days post-feeding (dpf). Gene expression analysis was used to verify the presence of carbonic anhydrase (CA) II, IV and XIII, Na+ H+ exchanger 3 (NHE3), the Na+ HCO3 − co-transporter (NBC) and V-type ATPase. CA IV expression was significantly down-regulated at 3dpf versus fasted controls. This was supported by activity analysis that showed a significant decrease in the amount of GPI-linked CA activity in isolated kidney membranes at 3dpf versus fasted controls. In addition, V-type ATPase activity was significantly up-regulated at 3dpf; no change in gene expression was observed. Both CA II and NHE3 expression was up-regulated at 3dpf, which may be related to post-prandial ion balance. These results suggest that Burmese pythons actively remodel their kidney after feeding, which would in part benefit renal HCO3 − clearance.


      PubDate: 2015-07-14T01:05:00Z
       
  • Sexual maturation and changes in water and salt transport components in
           the kidney and intestine of three-spined stickleback (Gasterosteus
           aculeatus L.)
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Steffen S. Madsen , Claus Weber , Andreas M. Nielsen , Mohammad Mohiseni , Maryline C. Bosssus , Christian K. Tipsmark , Bertil Borg
      Mature three-spined stickleback males use spiggin threads secreted from their kidney to glue together nest material. This requires strongly hypertrophied renal proximal tubular cells, which compromises renal osmoregulatory function during the breeding period. Experimental evidence suggests that the intestine takes over hypotonic fluid secretion at that stage but the mechanism is unexplored. To unravel the molecular mechanism we analyzed and compared transcript levels of several membrane proteins involved in water and salt transport in intestinal and renal tissues, in non-mature males (NM), mature males (MM), and mature females (MF). Aquaporin paralogs aqp1a, -3a, -8aa, -8ab, -10a, and -10b, two Na+,K+-ATPase alpha-1 subunit isoforms (nka547, nka976), Na+,K+,2Cl−-, and Na+,Cl−-cotransporters (nkcc1a, nkcc2, ncc), the cystic fibrosis transmembrane conductance regulator (cftr) and two claudin isoforms (cldn2, cldn15a) were expressed in the intestine and kidney in all groups. There were no differences in aqp and cldn expression between intestines of NM and MM; nkcc2 was lower and nka levels tended to be higher in intestines of MM than in NM. In the kidney, aqp1 and aqp8ab levels were lower in MM than in NM, whereas aqp3a, nkcc1a, cldn15a, and spiggin were markedly elevated. This was accompanied by marked hypertrophy of kidney tubules in MM. The data support an altered kidney function in terms of water handling in mature males, whereas there was no support for modified trans-epithelial water permeability or salt-secretory activity in the intestine of mature males. Salt-absorptive activity in the intestine may, however, be down-regulated during male maturation.


      PubDate: 2015-07-14T01:05:00Z
       
  • Localization of steroidogenic enzymes and Foxl2a in the gonads of mature
           zebrafish (Danio rerio)
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Morgane Caulier , François Brion , Edith Chadili , Cyril Turies , Benjamin Piccini , Jean-Marc Porcher , Yann Guiguen , Nathalie Hinfray
      In zebrafish, the identification of the cells expressing steroidogenic enzymes and their regulators is far from completely fulfilled though it could provide crucial information on the elucidation of the role of these enzymes. The aim of this study was to better characterize the expression pattern of steroidogenic enzymes involved in estrogen and androgen production (Cyp17-I, Cyp11c1, Cyp19a1a and Cyp19a1b) and one of their regulators (Foxl2a) in zebrafish gonads. By using immunohistochemistry, we localized the steroid-producing cells in mature zebrafish gonads and determined different expression patterns between males and females. All these steroidogenic enzymes and Foxl2a were detected both in the testis and ovary. In the testis, they were all localized both in Leydig and germ cells except Cyp19a1b which was only detected in germ cells. In the ovary, Cyp17-I, Cyp19a1a and Foxl2a were immunolocalized in both somatic and germ cells while Cyp19a1b was only detected in germ cells and Cyp11c1 in somatic cells. Moreover, Cyp19a1a and Foxl2a did not display exactly the same patterns of spatial localization but their expressions were correlated suggesting a possible regulation of cyp19a1a gene by Foxl2a in zebrafish. Comparative analysis revealed a dimorphic expression of Cyp11c1, Cyp19a1a, Cyp19a1b and Foxl2a between males and females. Overall, our study provides a detailed description of the expression of proteins involved in the biosynthesis of steroidal hormones at the cellular scale within gonads, which is critical to further elucidating the intimate roles of the enzymes and the use of the zebrafish as a model in the field of endocrinology.


      PubDate: 2015-07-14T01:05:00Z
       
  • Regional variation in energy storage strategies in American glass eels
           from Eastern Canada
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Mélanie Gaillard , Louis Bernatchez , Réjean Tremblay , Céline Audet
      Energy status was analyzed in glass eels captured during two early waves of arrival at the mouths of the Mersey River, Nova Scotia, Canada (MR), and Grande-Rivière-Blanche, Québec, Canada (GRB), and according to their salinity preference (freshwater, brackish, or saltwater). Glass eels captured in the GRB estuary were larger, more pigmented, and exhibited higher whole-body glycogen, phospholipid, and sterol and wax ester contents. Those from MR had a higher condition index and a higher whole-body triacylglycerol content, suggesting different patterns of storage and/or use of energy reserves. Within a river, a delay of two weeks in estuarine arrival was characterized by significantly lower energy reserves. No differences in energy storage were observed according to salinity preference. Thus, the results revealed the occurrence of different energy storage strategies according to glass eel migration distance and duration, but not according to salinity preference.


      PubDate: 2015-07-14T01:05:00Z
       
  • Characterization of six small HSP genes from Chironomus riparius (Diptera,
           Chironomidae): Differential expression under conditions of normal growth
           and heat-induced stress
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Raquel Martín-Folgar , Mercedes de la Fuente , Gloria Morcillo , José-Luis Martínez-Guitarte
      Small heat shock proteins (sHSPs) comprise the most numerous, structurally diverse, and functionally uncharacterized family of heat shock proteins. Several Hsp genes (Hsp 90, 70, 40, and 27) from the insect Chironomus riparius are widely used in aquatic toxicology as biomarkers for environmental toxins. Here, we conducted a comparative study and characterized secondary structure of the six newly identified sHsp genes Hsp17, Hsp21, Hsp22, Hsp23, Hsp24, and Hsp34. A characteristic α-crystallin domain is predicted in all the new proteins. Phylogenetic analysis suggests a strong relation to other sHSPs from insects and interesting evidence regarding evolutionary origin and duplication events. Comparative analysis of transcription profiles for Hsp27, Hsp70, and the six newly identified genes revealed that Hsp17, Hsp21, and Hsp22 are constitutively expressed under normal conditions, while under two different heat shock conditions these genes are either not activated or are even repressed (Hsp22). In contrast, Hsp23, Hsp24, and Hsp34 are significantly activated along with Hsp27 and Hsp70 during heat stress. These results strongly suggest functional differentiation within the small HSP subfamily and provide new data to help understand the coping mechanisms induced by stressful environmental stimuli.


      PubDate: 2015-07-14T01:05:00Z
       
  • Comparative methane emission by ratites: Differences in food intake and
           digesta retention level out methane production
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Samuel Frei , Jean-Michel Hatt , Sylvia Ortmann , Michael Kreuzer , Marcus Clauss
      Ratites differ in the anatomy of their digestive organs and their digesta excretion patterns. Ostriches (Struthio camelus) have large fermentation chambers and long digesta retention, emus (Dromaius novaehollandiae) have a short gut and short retention times, and rheas (Rhea americana) are intermediate. A recent study showed that ostriches produce as much methane (CH4) as expected for a similar-sized, non-ruminant mammalian herbivore. We hypothesized that emus and rheas produce less CH4 than ostriches. We individually measured, by chamber respirometry, the amount of O2 consumed as well as CO2 and CH4 emitted from six adult rheas (body mass 23.4±8.3kg) and two adult emus (33.5 and 32.0kg) during 23-hour periods on a pelleted lucerne diet. In contrast to previous studies, which classified emus as non-producers, we measured CH4 emissions at 7.39 and 6.25L/day for emus and 2.87±0.82L/day for rheas, which is close to values expected for similar-sized non-ruminant mammals for both species. O2 consumption was of a similar magnitude as reported previously. Across ratites, CH4 yield (L/kg dry matter intake) was positively correlated with mean retention time of food particles in the gut, similar to findings within ruminant species. In ratites, this relationship leads to similar body mass-specific CH4 production for a high intake/short retention and a low intake/long retention strategy. Therefore, when investigating CH4 production in herbivorous birds, it is advisable to consider various CH4 measures, not only yield or absolute daily amount alone.


      PubDate: 2015-07-14T01:05:00Z
       
  • Endocrine and immunological responses to adrenocorticotrophic hormone
           (ACTH) administration in juvenile harbor seals (Phoca vitulina) during
           winter and summer
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Mandy J. Keogh , Shannon Atkinson
      There is increasing interest in measuring endocrine and immune parameters in free-ranging seals and sea lions, but there is a lack of understanding in how an acute stress response, often associated with capture and handling, influences these parameters of interest. The main objective of this study was to assess the impact of a simulated stressor on both endocrine and immune parameters. During two seasons, exogenous adrenocorticotrophic hormone (ACTH) was administered to seven female juvenile harbor seals and the response of several hormones (cortisol, aldosterone, total and free thyroxine and total triiodothyronine) and immunological parameters (total and differential leukocyte counts and peripheral blood mononuclear cells (PBMC) proliferation) were assessed. Cortisol peaked at 165min (winter 203.1±84.7ng/ml; summer 205.3±65.7ng/ml) and remained significantly elevated 240min after ACTH infusion in both seasons. Aldosterone peaked at 90min (winter 359.3±249.3pg/ml; summer 294.1±83.7pg/ml) and remained elevated 240min after administration of ACTH in both seasons. An increase in circulating total white blood cells was driven primarily by the increase in neutrophils which occurred simultaneously with a decrease in lymphocytes leading to an overall increase in neutrophil to lymphocyte ratio. These findings demonstrate that a simulated stress response in juvenile harbor seals results in a predictable increase in both cortisol and aldosterone concentrations, and were associated with altered immunological parameters.


      PubDate: 2015-07-14T01:05:00Z
       
  • Is gill cortisol concentration a good acute stress indicator in fish'
           A study in rainbow trout and zebrafish
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Manuel Gesto , Juan Hernández , Marcos A. López-Patiño , José L. Soengas , Jesús M. Míguez
      Cortisol is the main biomarker of physiological stress in fish. It is usually measured in plasma, which requires blood collection. Though cortisol is produced in the anterior kidney, it can diffuse easily through cell membranes due to its lipophilic nature. Taking advantage of that, some non-invasive techniques have been developed to measure cortisol directly in the water from fish-holding tanks, in skin mucus or in scales. In this study, we explored the possibility to analyze fish cortisol from gill filaments as a reliable acute stress marker. Our results show that gill cortisol levels correlate well with plasma cortisol levels in both rainbow trout and zebrafish exposed or not to an acute stress protocol. Measuring cortisol in gill filaments increases the available possibilities for stress assessment in fish. Although this approach should yet be tested for its use with other stressors, it has several advantages: In relatively large fish (i.e. above 30g) gill cortisol levels could be measured in vivo. Sampling of gill biopsies is very fast and easy, and the procedure does not induce stress if properly performed, making it an ideal option for in vivo stress assessment. In small fish, the use of gill tissue to measure cortisol has important technical advantages with respect to the current methods using whole-body homogenates. Gill homogenates could be used directly for ELISA cortisol analysis, avoiding the need of tedious and expensive cortisol extraction protocols, and, since no organic solvent is required, contributing for a more environmentally friendly analysis.


      PubDate: 2015-07-14T01:05:00Z
       
  • The progressive onset of cholinergic and adrenergic control of heart rate
           during development in the green iguana, Iguana iguana
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Marina R. Sartori , Cleo A.C. Leite , Augusto S. Abe , Dane A. Crossley II , Edwin W. Taylor
      The autonomic control of heart rate was studied throughout development in embryos of the green iguana, Iguana iguana by applying receptor agonists and antagonists of the parasympathetic and sympathetic systems. Acetylcholine (Ach) slowed or stopped the heart and atropine antagonized the response to Ach indicating the presence of muscarinic cholinoceptors on the heart of early embryos. However, atropine injections had no impact on heart rate until immediately before hatching, when it increased heart rate by 15%. This cholinergic tonus increased to 34% in hatchlings and dropped to 24% in adult iguanas. Although epinephrine was without effect, injection of propranolol slowed the heart throughout development, indicating the presence of β-adrenergic receptors on the heart of early embryos, possibly stimulated by high levels of circulating catecholamines. The calculated excitatory tonus varied between 33% and 68% until immediately before hatching when it fell to 25% and 29%, a level retained in hatchlings and adults. Hypoxia caused a bradycardia in early embryos that was unaffected by injection of atropine indicating that hypoxia has a direct effect upon the heart. In later embryos and hatchlings hypoxia caused a tachycardia that was unaffected by injection of atropine. Subsequent injection of propranolol reduced heart rate both uncovering a hypoxic bradycardia in late embryos and abolishing tachycardia in hatchlings. Hypercapnia was without effect on heart rate in late stage embryos and in hatchlings.


      PubDate: 2015-07-14T01:05:00Z
       
  • Roles of leptin and ghrelin in adipogenesis and lipid metabolism of
           rainbow trout adipocytes in vitro
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Cristina Salmerón , Marcus Johansson , Maryam Asaad , Anna R. Angotzi , Ivar Rønnestad , Sigurd O. Stefansson , Elisabeth Jönsson , Björn Thrandur Björnsson , Joaquim Gutiérrez , Isabel Navarro , Encarnación Capilla
      Leptin and ghrelin are important regulators of energy homeostasis in mammals, whereas their physiological roles in fish have not been fully elucidated. In the present study, the effects of leptin and ghrelin on adipogenesis, lipolysis and on expression of lipid metabolism-related genes were examined in rainbow trout adipocytes in vitro. Leptin expression and release increased from preadipocytes to mature adipocytes in culture, but did not affect the process of adipogenesis. While ghrelin and its receptor were identified in cultured differentiated adipocytes, ghrelin did not influence either preadipocyte proliferation or differentiation, indicating that it may have other adipose-related roles. Leptin and ghrelin increased lipolysis in mature freshly isolated adipocytes, but mRNA expression of lipolysis markers was not significantly modified. Leptin significantly suppressed the fatty acid transporter-1 expression, suggesting a decrease in fatty acid uptake and storage, but did not affect expression of any of the lipogenesis or β-oxidation genes studied. Ghrelin significantly increased the mRNA levels of lipoprotein lipase, fatty acid synthase and peroxisome proliferator-activated receptor-β, and thus appears to stimulate synthesis of triglycerides as well as their mobilization. Overall, the study indicates that ghrelin, but not leptin seems to be an enhancer of lipid turn-over in adipose tissue of rainbow trout, and this regulation may at least partly be mediated through autocrine/paracrine mechanisms. The mode of action of both hormones needs to be further explored to better understand their roles in regulating adiposity in fish.


      PubDate: 2015-07-14T01:05:00Z
       
  • The neurotransmitters serotonin and glutamate accelerate the heart rate of
           the mosquito Anopheles gambiae
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Julián F. Hillyer , Tania Y. Estévez-Lao , Homa E. Mirzai
      Serotonin and glutamate are neurotransmitters that in insects are involved in diverse physiological processes. Both serotonin and glutamate have been shown to modulate the physiology of the dorsal vessel of some insects, yet until the present study, their activity in mosquitoes remained unknown. To test whether serotonin or glutamate regulate dorsal vessel physiology in the African malaria mosquito, Anopheles gambiae, live mosquitoes were restrained, and a video of the contracting heart (the abdominal portion of the dorsal vessel) was acquired. These adult female mosquitoes were then injected with various amounts of serotonin, glutamate, or a control vehicle solution, and additional videos were acquired at 2 and 10min post-treatment. Comparison of the videos taken before and after treatment revealed that serotonin accelerates the frequency of heart contractions, with the cardioacceleration being significantly more pronounced when the wave-like contractions of cardiac muscle propagate in the anterograde direction (toward the head). Comparison of the videos taken before and after treatment with glutamate revealed that this molecule is also cardioacceleratory. However, unlike serotonin, the activity of glutamate does not depend on whether the contractions propagate in the anterograde or the retrograde (toward the posterior of the abdomen) directions. Serotonin or glutamate induces a minor change or no change in the percentage of contractions and the percentage of the time that the heart contracts in the anterograde or the retrograde directions. In summary, this study shows that the neurotransmitters serotonin and glutamate increase the heart contraction rate of mosquitoes.


      PubDate: 2015-07-14T01:05:00Z
       
  • Existence of a photoinducible phase for ovarian development and
           photoperiod-related alteration of clock gene expression in a damselfish
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Yuki Takeuchi , Noriko Hada , Satoshi Imamura , Sung-Pyo Hur , Selma Bouchekioua , Akihiro Takemura
      The sapphire devil, Chrysiptera cyanea, is a reef-associated damselfish and their ovarian development can be induced by a long photoperiod. In this study, we demonstrated the existence of a photoinducible phase for the photoperiodic ovarian development in the sapphire devil. Induction of ovarian development under night-interruption light schedules and Nanda–Hamner cycles revealed that the photoinducible phase appeared in a circadian manner between ZT12 and ZT13. To characterize the effect of photoperiod on clock gene expression in the brain of this species, we determined the expression levels of the sdPer1, sdPer2, sdCry1, and sdCry2 clock genes under constant light and dark conditions (LL and DD) and photoperiodic (short and long photoperiods). The expression of sdPer1 exhibited clear circadian oscillation under both LL and DD conditions, while sdPer2 and sdCry1 expression levels were lower under DD than under LL conditions and sdCry2 expression was lower under LL than under DD conditions. These results suggest a key role for sdPer1 in circadian clock cycling and that sdPer2, sdCry1, and sdCry2 are light-responsive clock genes in the sapphire devil. After 1week under a long photoperiod, we observed photoperiod-related changes in sdPer1, sdPer2, and sdCry2 expression, but not in sdCry1 expression. These results suggest that the expression patterns of some clock genes exhibit seasonal variation according to seasonal changes in day length and that such seasonal alteration of clock gene expression may contribute to seasonal recognition by the sapphire devil.


      PubDate: 2015-07-14T01:05:00Z
       
  • Functional dynamics of claudin expression in Japanese medaka (Oryzias
           latipes): Response to environmental salinity
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Maryline C. Bossus , Steffen S. Madsen , Christian K. Tipsmark
      Salinity regulation of 13 claudin paralogs was investigated in osmoregulatory organs of euryhaline Japanese medaka. They were identified by blast-search in the medaka genome database based on representation in osmoregulatory organs of other teleosts. Our hypothesis was that, because of their sequence similarities to mammalian orthologs previously characterized as barrier- and ion-selective channel-forming proteins, these paralogs would respond to salinity according to expected modulation of osmoregulatory function. Cldn10c, -10d, -10e, -10f, -27a, -28a, -28b and -30c had 4- to 100-fold higher expression in gill than other examined organs. Two splice variants of cldn10b were predominantly expressed in kidney, while cldn15a, -15b and -25 were found mainly in intestine. In gills, cldn27a, -28a, -28b and -30c did not change between fresh water (FW) and seawater (SW)-acclimated fish, while cldn10c, -10d, -10e, and -10f were most abundant in SW. Short-term SW transfer induced up-regulation of cldn10 gill paralogs after 1day, decrease in cldn28b and no difference for cldn27a, -28a and -30c. The reverse pattern was observed after FW transfer of SW medaka. Intestinal cldn15a and -25 did not differ between FW and SW fish. However, cldn15b was 10-fold higher in FW than SW, suggesting a role in functional modulation of the intestine related to water and salt transport. In kidney, cldn10bs were elevated in SW fish, suggesting a role in paracellular ion transport in the marine nephron. Based on in silico analysis, most gill Cldn10s were predicted to form cation pores, whereas Cldn27a, 28a, 28b and 30c may increase epithelial resistance.


      PubDate: 2015-07-14T01:05:00Z
       
  • Development of a time-resolved fluoroimmunoassay for salmon insulin-like
           growth factor binding protein-1b
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Miki Fukuda , Nobuto Kaneko , Kohei Kawaguchi , Ernst M. Hevrøy , Akihiko Hara , Munetaka Shimizu
      In salmon plasma/serum, three major insulin-like growth factor binding proteins (IGFBPs) are consistently detected at 22-, 28- and 41-kDa. The 22-kDa form has been identified as IGFBP-1b and shown to increase under catabolic conditions. We developed a competitive time-resolved fluoroimmunoassay (TR-FIA) for salmon IGFBP-1b. Purified salmon IGFBP-1b was used for biotin-labeling, assay standard and antiserum production. The TR-FIA did not cross-react with the 41-kDa form (IGFBP-2b) but showed 3% cross-reactivity with the 28-kDa form (IGFBP-1a). It measured IGFBP-1b levels as low as 0.4ng/ml, and ED80 and ED20 were 0.9 and 24.6ng/ml, respectively. There appears to be little interference by IGF-I. Using the TR-FIA, serum IGFBP-1b levels were measured in individually-tagged underyearling masu salmon fed or fasted for 5weeks, or fasted for 3weeks followed by refeeding for 2weeks. Fasting for 3weeks significantly increased circulating IGFBP-1b levels, while it returned to the basal levels after prolonged fasting for additional 2weeks. Serum IGFBP-1b level negatively correlated with body weight, condition factor, specific growth rate and serum IGF-I level. During parr–smolt transformation of masu salmon, average circulating IGFBP-1b levels were the highest in May. There was a positive correlation between serum IGFBP-1b and IGF-I, which is in contrast to that in the fasting/feeding experiment. IGFBP-1b also showed a positive relationship with gill Na+, K+-ATPase activity. These results suggest that the relationship between circulating IGFBP-1b and IGF-I during smoltification differs from that during fasting and IGFBP-1b may play a role in the development of hypoosmoregulatory ability.


      PubDate: 2015-07-14T01:05:00Z
       
  • Comparative study of enzymatic antioxidants in muscle of elasmobranch and
           teleost fishes
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Marcela Vélez-Alavez , Juan A. De Anda-Montañez , Felipe Galván-Magaña , Tania Zenteno-Savín
      Exercise may cause an imbalance between pro-oxidants and antioxidants. In skeletal muscle, oxygen flow can increase considerably during vigorous exercise. The antioxidant system in athletes contributes to neutralize the concomitant rise in reactive oxygen species (ROS) production. The objective of this study was to compare the antioxidant system in muscle of three species of elasmobranchs and teleosts, considering differences in swimming capacity among species within each group and evolutionary differences between the two groups. Muscle samples were collected from elasmobranchs (Isurus oxyrinchus, Prionace glauca, Mustelus henlei) and teleosts (Totoaba macdonaldi, Kajikia audax and Coryphaena hippurus) in the coast of the Baja California peninsula, Mexico. The enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) was determined by spectrophotometry. The activity of the antioxidant enzymes CAT, GPx and GST was higher in elasmobranchs, as a group, than in teleosts. In fish species with high swimming capacities, P. glauca, K. audax and C. hippurus, antioxidant enzyme activity was higher in comparison with species with lower swimming capacities, M. henlei and T. macdonaldi. It is possible that antioxidant enzymes, particularly SOD, GPx and GST, contribute to avoidance of oxidative damage in teleost and elasmobranch species with higher swimming capacities. The antioxidant enzyme activities in fish appear to depend mainly on their swimming capacity and life style rather than the evolutionary group (elasmobranchs, teleosts).


      PubDate: 2015-07-14T01:05:00Z
       
  • Brain glycogen supercompensation after different conditions of induced
           hypoglycemia and sustained swimming in rainbow trout (Oncorhynchus mykiss)
           
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): A.M. Blanco , M. Gómez-Boronat , J. Pérez-Maceira , M.J. Mancebo , M. Aldegunde
      Brain glycogen is depleted when used as an emergency energy substrate. In mammals, brain glycogen levels rebound to higher than normal levels after a hypoglycemic episode and a few hours after refeeding or administration of glucose. This phenomenon is called glycogen supercompensation. However, this mechanism has not been investigated in lower vertebrates. The aim of this study was therefore to determine whether brain glycogen supercompensation occurs in the rainbow trout brain. For this purpose, short-term brain glucose and glycogen contents were determined in rainbow trout after being subjected to the following experimental conditions: i) a 5-day or 10-day fasting period and refeeding; ii) a single injection of insulin (4mgkg−1) and refeeding; and iii) sustained swimming and injection of glucose (500mgkg−1). Food deprivation during the fasting periods and insulin administration both induced a decrease in glucose and glycogen levels in the brain. However, only refeeding after 10days of fasting significantly increased the brain glycogen content above control levels, in a clear short-term supercompensation response. Unlike in mammals, prolonged exercise did not alter brain glucose or glycogen levels. Furthermore, brain glycogen supercompensation was not observed after glucose administration in fish undergoing sustained swimming. To our knowledge, this is the first study providing direct experimental evidence for the existence of a short-term glycogen supercompensation response in a teleost brain, although the response was only detectable after prolonged fasting.


      PubDate: 2015-07-14T01:05:00Z
       
  • Ammonia and urea excretion in the swimming crab Portunus trituberculatus
           exposed to elevated ambient ammonia-N
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Qin Ren , Luqing Pan , Qun Zhao , Lingjun Si
      In the present study of the swimming crab Portunus trituberculatus exposed to 0, 1, and 5mgL−1 NH4Cl, the effects of ammonia exposure on ammonia and urea content in hemolymph; activity of H+-ATPase (subunit A) and Na+/K+-ATPase (α-subunit) (NKA) in gills; mRNA expression levels of the crustacean Rh-like ammonia transporter (Rh), K+ Channel, Na+/K+/2Cl− co-transporter (NKCC), Na+/H+-exchanger (NHE), urea transporter (UT) and vesicle associated membrane protein (VAMP) in gills were investigated. The ultrastructure of gills was also evaluated. All these results in this study showed a dose-dependent effect with ammonia exposure concentration. The data displayed a significant increase in hemolymph ammonia and urea concentrations under ammonia exposure. The up-regulation of Rh mRNA together with up-regulation of K+-channel mRNA, NKA activity, down-regulation of NKCC and NHE mRNA suggested a coordinated protective response to maintain a relatively low ammonia concentration in the body fluids during ambient ammonia exposure. The up-regulation of VAMP, H+-ATPase activity along with the ultrastructure of gills suggested a mechanism of exocytotic ammonia excretion that may exit in the gill of P. trituberculatus. An increased production of urea and the up-regulated expression of UT suggested that the crab can detoxify elevated ammonia levels in the body fluids into urea when pathways of ammonia excretion are decreased after long term ammonia exposure.


      PubDate: 2015-07-14T01:05:00Z
       
  • Effect of salinity changes on olfactory memory-related genes and hormones
           in adult chum salmon Oncorhynchus keta
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Na Na Kim , Young Jae Choi , Sang-Gu Lim , Minhwan Jeong , Deuk-Hee Jin , Cheol Young Choi
      Studies of memory formation have recently concentrated on the possible role of N-methyl-d-aspartate receptors (NRs). We examined changes in the expression of three NRs (NR1, NR2B, and NR2C), olfactory receptor (OR), and adrenocorticotropic hormone (ACTH) in chum salmon Oncorhynchus keta using quantitative polymerase chain reaction (QPCR) during salinity change (seawater→50% seawater→freshwater). NRs were significantly detected in the diencephalon and telencephalon and OR was significantly detected in the olfactory epithelium. The expression of NRs, OR, and ACTH increased after the transition to freshwater. We also determined that treatment with MK-801, an antagonist of NRs, decreased NRs in telencephalon cells. In addition, a reduction in salinity was associated with increased levels of dopamine, ACTH, and cortisol (in vivo). Reductions in salinity evidently caused NRs and OR to increase the expression of cortisol and dopamine. We concluded that memory capacity and olfactory imprinting of salmon is related to the salinity of the environment during the migration to spawning sites. Furthermore, salinity affects the memory/imprinting and olfactory abilities, and cortisol and dopamine is also related with olfactory-related memories during migration.


      PubDate: 2015-07-14T01:05:00Z
       
  • Restriction of glucose and fructose causes mild oxidative stress
           independently of mitochondrial activity and reactive oxygen species in
           Drosophila melanogaster
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Bohdana M. Rovenko , Olga I. Kubrak , Dmytro V. Gospodaryov , Ihor S. Yurkevych , Alberto Sanz , Oleh V. Lushchak , Volodymyr I. Lushchak
      Our recent study showed different effects of glucose and fructose overconsumption on the development of obese phenotypes in Drosophila. Glucose induced glucose toxicity due to the increase in circulating glucose, whereas fructose was more prone to induce obesity promoting accumulation of reserve lipids and carbohydrates (Rovenko et al., Comp. Biochem. Physiol. A Mol. Integr. Physiol. 2015, 180, 75–85). Searching for mechanisms responsible for these phenotypes in this study, we analyzed mitochondrial activity, mitochondrial density, mtROS production, oxidative stress markers and antioxidant defense in fruit flies fed 0.25%, 4% and 10% glucose or fructose. It is shown that there is a complex interaction between dietary monosaccharide concentrations, mitochondrial activity and oxidative modifications to proteins and lipids. Glucose at high concentration (10%) reduced mitochondrial protein density and consequently respiration in flies, while fructose did not affect these parameters. The production of ROS by mitochondria did not reflect activities of mitochondrial complexes. Moreover, there was no clear connection between mtROS production and antioxidant defense or between antioxidant defense and developmental survival, shown in our previous study (Rovenko et al., Comp. Biochem. Physiol. A Mol. Integr. Physiol. 2015, 180, 75–85). Instead, mtROS and antioxidant machinery cooperated to maintain a redox state that determined survival rates, and paradoxically, pro-oxidant conditions facilitated larva survival independently of the type of carbohydrate. It seems that in this complex system glucose controls the amount of oxidative modification regulating mitochondrial activity, while fructose regulates steady-state mRNA levels of antioxidant enzymes.


      PubDate: 2015-07-14T01:05:00Z
       
  • The thermal stress response to diel vertical migration in the hyperiid
           amphipod Phronima sedentaria
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Leanne E. Elder , Brad A. Seibel
      The hyperiid amphipod Phronima sedentaria experiences a temperature change of 15°C during diel migration in the Eastern Tropical North Pacific (ETNP) from 8–10°C at depth to 25–27°C at night in the surface waters. The aim of this study was to determine if the natural temperature gradient experienced by P. sedentaria results in a thermal stress response. Individuals were initially exposed to their night time temperatures (23°C) and subsequently subjected to temperatures within and above the range they typically experience. In the Eastern Tropical North Pacific P. sedentaria tolerates its normal night-time temperature (~23°C), but only for the duration of its stay there (~9h). Longer exposures (24h) result in elevated heat shock protein (hsp) expression. 29°C results in hsp expression, increased lactate production and 50% mortality at all exposure durations. This represents an upper critical temperature. Understanding the adaptations of pelagic amphipods to their current environment will help predict the physiological impacts of global warming for amphipods and their predators.


      PubDate: 2015-07-14T01:05:00Z
       
  • Acute heat stress up-regulates neuropeptide Y precursor mRNA expression
           and alters brain and plasma concentrations of free amino acids in chicks
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Kentaro Ito , Mohammad A. Bahry , Yang Hui , Mitsuhiro Furuse , Vishwajit S. Chowdhury
      Heat stress causes an increase in body temperature and reduced food intake in chickens. Several neuropeptides and amino acids play a vital role in the regulation of food intake. However, the responses of neuropeptides and amino acids to heat-stress-induced food-intake regulation are poorly understood. In the current study, the hypothalamic mRNA expression of some neuropeptides related to food intake and the content of free amino acids in the brain and plasma was examined in 14-day-old chicks exposed to a high ambient temperature (HT; 40±1°C for 2 or 5h) or to a control thermoneutral temperature (CT; 30±1°C). HT significantly increased rectal temperature and plasma corticosterone level and suppressed food intake. HT also increased the expression of neuropeptide Y (NPY) and agouti-signaling protein (ASIP) precursor mRNA, while no change was observed in pro-opiomelanocortin, cholecystokinin, ghrelin, or corticotropin-releasing hormone precursor mRNA. It was further found that the diencephalic content of free amino acids – namely, tryptophan, leucine, isoleucine, valine and serine – was significantly higher in HT chicks with some alterations in their plasma amino acids in comparison with CT chicks. The induction of NPY and ASIP expression and the alteration of some free amino acids during HT suggest that these changes can be the results or causes the suppression of food intake.


      PubDate: 2015-07-14T01:05:00Z
       
  • Myoglobin oxygenation and autoxidation in three reptilian species
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Signe Helbo , Amanda G. Bundgaard , Angela Fago
      Differences between species in the oxygen (O2) affinity (P50) of myoglobin (Mb) may serve to fine tune O2 supply to cardiac and skeletal muscle in ectotherms. In support of this view, it has been shown that fish Mb O2 affinities differ between species when measured at the same temperature, but are in fact similar when adjusted for in vivo muscle temperatures, most likely to maintain intracellular O2 delivery in species adapted to different environments. It is unknown whether similar adaptations exist in the O2 affinity of Mb from reptiles, despite this group of ectothermic vertebrates displaying great variation in the tolerance to both temperature and hypoxia. In this study, we have purified Mb from muscle tissues of three reptilian species (turtle, tortoise and alligator) with different lifestyles. We have measured O2 binding characteristics and autoxidation rates of the three Mbs and measured the effects of temperature, lactate and blocking of reactive thiols on the O2 affinity of turtle Mb. Our data show that, at a constant temperature, reptilian Mbs have similar O2 affinities that are lower than those of mammalian Mbs, which may optimize intracellular O2 transport at lower body temperatures. Reptilian Mbs have lower autoxidation rates than both mammalian and fish Mbs, which may be beneficial during oxidative stress. Furthermore, the O2 affinity of turtle Mb is without allosteric control and independent of either lactate or thiol covalent modification. This study reveals some common adaptive patterns in the temperature-dependent regulation of Mb oxygenation in vertebrates.


      PubDate: 2015-07-14T01:05:00Z
       
  • Editorial Board
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187




      PubDate: 2015-07-14T01:05:00Z
       
  • Consequences of complex environments: Temperature and energy intake
           interact to influence growth and metabolic rate
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Zachary R. Stahlschmidt , Alicia D. Jodrey , Rachel L. Luoma
      The field of comparative physiology has a rich history of elegantly examining the effects of individual environmental factors on performance traits linked to fitness (e.g., thermal performance curves for locomotion). However, animals live in complex environments wherein multiple environmental factors co-vary. Thus, we investigated the independent and interactive effects of temperature and energy intake on the growth and metabolic rate of juvenile corn snakes (Pantherophis guttatus) in the context of shifts in complex environments. Unlike previous studies that imposed constant or fluctuating temperature regimes, we manipulated the availability of preferred thermal microclimates (control vs. relatively warm regimes) for eight weeks and allowed snakes to behaviorally thermoregulate among microclimates. By also controlling for energy intake, we demonstrate an interactive effect of temperature and energy on growth—relevant temperature shifts had no effect on snakes' growth when energy intake was low and a positive effect on growth when energy intake was high. Thus, acclimation to relatively warm thermal options can result in increased rates of growth when food is abundant in a taxon in which body size confers fitness advantages. Temperature and energy also interactively influenced metabolic rate—snakes in the warmer temperature regime exhibited reduced metabolic rate (O2 consumption rate at 25°C and 30°C) if they had relatively high energy intake. Although we advocate for continued investigation into the effects of complex environments on other traits, our results indicate that warming may actually benefit important life history traits in some taxa and that metabolic shifts may underlie thermal acclimation.


      PubDate: 2015-07-14T01:05:00Z
       
  • Role of the GH-IGF-1 system in Atlantic salmon and rainbow trout
           postsmolts at elevated water temperature
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Ernst M. Hevrøy , Christian K. Tipsmark , Sofie C. Remø , Tom Hansen , Miki Fukuda , Thomas Torgersen , Vibeke Vikeså , Pål A. Olsvik , Rune Waagbø , Munetaka Shimizu
      A comparative experiment with Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) postsmolts was conducted over 35days to provide insight into how growth, respiration, energy metabolism and the growth hormone (GH) and insulin-like growth factor 1 (IGF-1) system are regulated at elevated sea temperatures. Rainbow trout grew better than Atlantic salmon, and did not show reduced growth at 19°C. Rainbow trout kept at 19°C had increased blood hemoglobin concentration compared to rainbow trout kept at 13°C, while salmon did not show the same hemoglobin response due to increased temperature. Both species showed reduced length growth and decreased muscle glycogen stores at 19°C. Circulating IGF-1 concentration was higher in rainbow trout than in Atlantic salmon, but was not affected by temperature in either species. Plasma IGF-binding protein 1b (IGFBP-1b) concentration was reduced in Atlantic salmon reared at 19°C after 15days but increased in rainbow trout at 19 °C after 35days. The igfbp1b mRNA level in liver showed a positive correlation to plasma concentrations of glucose and IGFBP-1b, suggesting involvement of this binding protein in carbohydrate metabolism at 19°C. At this temperature muscle igfbp1a mRNA was down-regulated in both species. The muscle expression of this binding protein correlated negatively with muscle igf1 and length growth. The plasma IGFBP-1b concentration and igfbp1b and igfbp1a expression suggests reduced muscle igf1 signaling at elevated temperature leading to glucose allostasis, and that time course is species specific due to higher thermal tolerance in rainbow trout.


      PubDate: 2015-07-14T01:05:00Z
       
  • An appraisal of the use of an infrared digital monitoring system for
           long-term measurement of heart rate in reptilian embryos
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Marina R. Sartori , Edwin W. Taylor , Augusto S. Abe , Dane A. Crossley II
      Measurement of heart rate (f H) in embryonic reptiles has previously imposed some degree of invasive treatment on the developing embryo. Recently a non-invasive technique of f H detection from intact eggs was developed for commercial avian breeders and has since been used in biological research. This device uses infrared light, enabling it to detect heartbeats in very early embryos. However, infrared light is a source of heat and extended enclosure of an egg in the device is likely to affect temperature with consequent effects on physiological processes, including f H. We studied the effect of use of the monitor on the temperature of eggs and on f H in two species of reptiles, the snapping turtle (Chelydra serpentina) and the green iguana (Iguana iguana). Egg temperature increased from a room temperature of 27–28°C, by 26% in turtles and 14% in iguanas over 1h of enclosure, resulting in an increase in f H of 76–81% in turtles and 35–50% iguanas. These effects on f H can either be avoided by brief enclosure of each egg in the monitor or measured and accounted for during the design of long-term experiments.


      PubDate: 2015-07-14T01:05:00Z
       
  • Biochemical responses over time in common carp Cyprinus carpio (Teleostei,
           Cyprinidae) during fed supplementation with α-lipoic acid
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Alain D. Enamorado , Atila C. Martins , Juliana A. Flores , Marcelo Borges Tesser , Sergiane S. Caldas , Ednei G. Primel , José Maria Monserrat
      The current study aimed to evaluate the influence of lipoic acid (LA) supplementation (439.84±6.71mg LA/kg feed) on antioxidants responses throughout the time in intestine, liver and muscle of juvenile common carp Cyprinus carpio. Two experimental groups were fed during four weeks with a diet with or without LA. Glutathione-S-transferase (GST) activity, glutathione (GSH) content, antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (TBARS) were evaluated in these organs. Also, a technique to measure protein disulfide bonds and sulfhydryl groups was optimized for intestine samples. GST activity was significantly higher (p<0.05) in intestine after two weeks of supplementation. GSH content was also significantly higher (p<0.05) in intestine, liver and muscle of fish fed with LA after two and three weeks, respectively. Total capacity antioxidant against peroxyl radicals was significantly increased (p<0.05) in the muscle of animals fed with LA after the fourth week. Concentration of disulfide bonds was higher in the intestine of fish fed with LA but this group also showed higher concentration of sulfhydryl groups (p<0.05). It is concluded that supplementation with LA is a safe strategy to induce antioxidant responses and improves the antioxidant status in different organs of common carp. Two week of supplementation are required to induce antioxidant responses in intestine and liver and three week for muscle.


      PubDate: 2015-07-14T01:05:00Z
       
  • Hatching behavior of eastern long-necked turtles (Chelodina longicollis):
           The influence of asynchronous environments on embryonic heart rate and
           phenotype
    • Abstract: Publication date: October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 188
      Author(s): Jessica K. McGlashan , Fiona K. Loudon , Michael B. Thompson , Ricky-John Spencer
      Variable temperatures within a nest cause asynchronous development within clutches of freshwater turtle embryos, yet synchronous hatching occurs and is thought to be an important survival strategy for hatchlings. Metabolic compensation and circadian rhythms in heart rates of embryonic turtles indicate the potential of communication between embryos in a nest. Heart rates were used to identify metabolic circadian rhythms in clutches of an Australian freshwater turtle (Chelodina longicollis) and determine whether embryos metabolically compensate and hatch synchronously when incubated in asynchronous environments. The effects of a group environment during incubation on egg development and incubation period were also investigated during the final 3weeks of development. Chelodina longicollis hatch synchronously and metabolically compensate so that less advanced embryos catch up to more advanced clutch-mates. Heart rates of embryos remained stable from week 4–7 in asynchronous (M=89bpm) and synchronous (M=92bpm) groups and declined in the final 2weeks of incubation (M=72 and 77bpm). Circadian rhythms were present throughout development and diel heart rates of embryos in asynchronous groups showed less deviation from the mean (M=−0.5bpm) than synchronous groups (M=−4bpm). Eggs incubated in groups had a significantly shorter incubation period than eggs incubated individually. Phenotypic traits including size, performance, and growth of all hatchlings were not affected. Egg position within a turtle nest is important for coordinating development throughout incubation and facilitating synchronous hatching.


      PubDate: 2015-07-14T01:05:00Z
       
 
 
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