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  Subjects -> BIOLOGY (Total: 2849 journals)
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BIOCHEMISTRY (215 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: 201)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 10)
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: 91)
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: 100)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 31)
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: 4)
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: 3)
Biochemistry     Full-text available via subscription   (Followers: 160)
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: 8)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 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: 20)
BMC Biochemistry     Open Access   (Followers: 8)
BMC Chemical Biology     Open Access   (Followers: 4)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 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: 9)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 3)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)

        1 2 3     

Journal Cover   Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [3 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2812 journals]
  • 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
       
  • A nutrigenomic approach to detect nutritional stress from gene expression
           in blood samples drawn from Steller sea lions
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Jérôme Spitz , Vanessa Becquet , David A.S. Rosen , Andrew W. Trites
      Gene expression profiles are increasingly being used as biomarkers to detect the physiological responses of a number of species to disease, nutrition, and other stressors. However, little attention has been given to using gene expression to assess the stressors and physiological status of marine mammals. We sought to develop and validate a nutrigenomic approach to quantify nutritional stress in Steller sea lions (Eumetopias jubatus). We subjected 4 female Steller sea lions to 3 feeding regimes over 70-day trials (unrestricted food intake, acute nutritional stress, and chronic nutritional stress), and drew blood samples from each animal at the end of each feeding regime. We then extracted the RNA of white blood cells and measured the response of 8 genes known to react to diet restriction in terrestrial mammals. Overall, we found that the genomic response of Steller sea lions experiencing nutritional stress was consistent with how terrestrial mammals respond to dietary restrictions. Our nutritionally stressed sea lions down-regulated some cellular processes involved in immune response and oxidative stress, and up-regulated pro-inflammatory responses and metabolic processes. Nutrigenomics appears to be a promising means to monitor nutritional status and contribute to mitigation measures needed to assist in the recovery of Steller sea lions and other at-risk species of marine mammals.


      PubDate: 2015-07-14T01:05:00Z
       
  • Anti-oxidative responses of zebrafish (Danio rerio) gill, liver and brain
           tissues upon acute cold shock
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Su Mei Wu , Jia-Hao Liu , Li-Hsin Shu , Ching Hsein Chen
      The present study seeks to detect oxidative damage and to compare anti-oxidative responses among liver, gills and brain of adult zebrafish that were cooled from 28°C (control) to 12°C (treatment) for 0–24h. The lipid peroxidation of liver, gill and brain tissues significantly increased at 1h after transfer, but reactive oxygen species in the treatment group increased significantly after 24h as compared to the control. The fish were found to develop a cascading anti-oxidative mechanism beginning with an increase in Cu/Zn-SOD levels, followed by increased CAT and GPx mRNA expressions in the three tissue types. Both smtB and mt2 mRNAs increased in the hepatic and brain tissues following 1h of cold stress, but only smtB exhibited a significant increase in the gills at 1h and 6h after transfer to 12°C. Furthermore, cellular apoptosis in the brain was not evident after cold shock, but liver and gills showed cellular apoptosis at 1–3h, with another peak in the liver at 6h after cold shock. The results suggest that the cold shock induced oxidative stress, and the enzymatic (SOD, GPx and CAT) and non-enzymatic (mt-2 and smt-B) mRNA expressions all play a role in the resulting anti-oxidation within 1–6h of cold shock. A functional comparison showed that the brain had the most powerful antioxidant defense system of the three tissue types since it had the highest smtB mRNA expression and a lower level of cell apoptosis than the liver and gills after exposure to cold stress.


      PubDate: 2015-07-14T01:05:00Z
       
  • Two cholecystokinin receptor subtypes are identified in goldfish, being
           the CCKAR involved in the regulation of intestinal motility
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): A.B. Tinoco , A.I. Valenciano , M. Gómez-Boronat , A.M. Blanco , L.G. Nisembaum , N. De Pedro , M.J. Delgado
      Cholecystokinin (CCK) plays a key role in the digestive physiology of vertebrates. However, very little is known about the role of CCK on intestinal functions in fish. The present study identifies two CCK receptor subtypes in a stomachless teleost, the goldfish (Carassius auratus), and investigates by using an in vitro system their involvement mediating the effects of the sulfated octapeptide of CCK (CCK-8S) on the motility of isolated proximal intestine. Partial-length mRNAs encoding two CCK receptor isoforms (CCKAR and CCKBR.I) were sequenced and the structural analysis showed that both receptors belong to the G-protein coupled receptor superfamily. Both goldfish CCK receptor sequences were more closely related to zebrafish sequences, sharing the lowest similarities with cavefish and tilapia. The highest expression of goldfish CCKAR was observed along the whole intestine whereas the CCKBR gen was predominantly expressed in the hypothalamus, vagal lobe and posterior intestine. Application of CCK-8S to the organ bath evoked a concentration-dependent contractile response in intestine strips. The contractions were not blocked by either tetrodotoxin or atropine, suggesting that CCK-8S acts on the gut smooth muscle directly. Preincubations of intestine strips with devazepide and L365,260 (CCKAR and CCKBR receptor selective antagonists) showed that the CCK-8S-induced contraction could be partially mediated by the CCKAR receptor subtype, which is also the most abundant CCK receptor found in gastrointestinal tissues. In conclusion, two CCK receptors with a differential distribution pattern has been identified in goldfish, and the CCKAR subtype is mainly involved in the regulation of intestinal motility by the CCK-8S.


      PubDate: 2015-07-14T01:05:00Z
       
  • 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
       
  • A sea urchin Na+K+2Cl− cotransporter is involved in the maintenance
           of calcification-relevant cytoplasmic cords in Strongylocentrotus
           droebachiensis larvae
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Wiebke C. Basse , Magdalena A. Gutowska , Ulrike Findeisen , Meike Stumpp , Sam Dupont , Daniel J. Jackson , Nina Himmerkus , Frank Melzner , Markus Bleich
      The cellular mechanisms of calcification in sea urchin larvae are still not well understood. Primary mesenchyme cells within the larval body cavity form a syncytium to secrete CaCO3 spicules from intracellular amorphous CaCO3 (ACC) stores. We studied the role of Na+K+2Cl− cotransporter (NKCC) in intracellular ACC accumulation and larval spicule formation of Strongylocentrotus droebachiensis. First, we incubated growing larvae with three different loop diuretics (azosemide, bumetanide, and furosemide) and established concentration-response curves. All loop diuretics were able to inhibit calcification already at concentrations that specifically inhibit NKCC. Calcification was most effectively inhibited by azosemide (IC50 =6.5μM), while larval mortality and swimming ability were not negatively impacted by the treatment. The inhibition by bumetanide (IC50 =26.4μM) and furosemide (IC50 =315.4μM) resembled the pharmacological fingerprint of the mammalian NKCC1 isoform. We further examined the effect of azosemide on the maintenance of cytoplasmic cords and on the occurrence of calcification vesicles using fluorescent dyes (calcein, FM1-43). Fifty micromolars of azosemide inhibited the maintenance of cytoplasmic cords and resulted in increased calcein fluorescence within calcification vesicles. The expression of NKCC in S. droebachiensis was verified by PCR and Western blot with a specific NKCC antibody. In summary, the pharmacological profile of loop diuretics and their specific effects on calcification in sea urchin larvae suggest that they act by inhibition of NKCC via repression of cytoplasmic cord formation and maintenance.


      PubDate: 2015-07-14T01:05:00Z
       
  • Energetic costs of protein synthesis do not differ between red- and
           white-blooded Antarctic notothenioid fishes
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Johanne M. Lewis , Theresa J. Grove , Kristin M. O’Brien
      Antarctic icefishes (Family Channichthyidae) within the suborder Notothenioidei lack the oxygen-binding protein hemoglobin (Hb), and six of the 16 species of icefishes lack myoglobin (Mb) in heart ventricle. As iron-centered proteins, Hb and Mb can promote the formation of reactive oxygen species (ROS) that damage biological macromolecules. Consistent with this, our previous studies have shown that icefishes have lower levels of oxidized proteins and lipids in oxidative muscle compared to red-blooded notothenioids. Because oxidized proteins are usually degraded by the 20S proteasome and must be resynthesized, we hypothesized that rates of protein synthesis would be lower in icefishes compared to red-blooded notothenioids, thereby reducing the energetic costs of protein synthesis and conferring a benefit to the loss of Hb and Mb. Rates of protein synthesis were quantified in hearts, and the fraction of oxygen consumption devoted to protein synthesis was measured in isolated hepatocytes and cardiomyocytes of notothenioids differing in the expression of Hb and cardiac Mb. Neither rates of protein synthesis nor the energetic costs of protein synthesis differed among species, suggesting that red-blooded species do not degrade and replace oxidatively modified proteins at a higher rate compared to icefishes but rather, persist with higher levels of oxidized proteins.


      PubDate: 2015-07-14T01:05:00Z
       
  • Transcript levels of the soluble sperm factor protein phospholipase C zeta
           1 (PLCζ1) increase through induced spermatogenesis in European eel
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Marina Morini , David S. Peñaranda , María C. Vílchez , Víctor Gallego , Rasoul Nourizadeh-Lillabadi , Juan F. Asturiano , Finn-Arne Weltzien , Luz Pérez
      Activation at fertilization of the vertebrate egg is triggered by Ca2+ waves. Recent studies suggest the phospholipase C zeta (PLCζ), a sperm-specific protein, triggers egg activation by an IP3-mediated Ca2+ release and allow Ca2+ waves at fertilization. In the present study we cloned, characterized, and phylogenetically positioned the European eel PLCζ (PLCζ1). It is 1521bp long, with 10 exons encoding an open reading frame of 506 amino acids. The amino acid sequence contains an EF-hand domain, X and Y catalytic domains, and a carboxy-terminal C2 domain, all typical of other PLCζ orthologous. The tissue distribution was studied, and the gene expression was determined in testis during induced sexual maturation at three different thermal regimes. Also, brain and pituitary expression was studied through sex maturation at constant temperature. plcζ1 was expressed in brain of male and female, in testis but not in ovaries. By first time in vertebrates, it is reported plcζ1 expression in the pituitary gland. Testis plcζ1 expression increased through spermatogenesis under all the thermal regimes, but being significantly elevated at lower temperatures. It was very low when testis contained only spermatogonia or spermatocytes, while maximum expression was found during spermiogenesis. These results support the hypothesis for an eel sperm-specific PLCζ1 inducing egg activation, similarly to mammals and some teleosts, but different from some other teleost species, which express this protein in ovaries, but not in testes.


      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
       
  • Differential impacts of elevated CO2 and acidosis on the energy budget of
           gill and liver cells from Atlantic cod, Gadus morhua
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): L.S. Stapp , C.M. Kreiss , H.O. Pörtner , G. Lannig
      Ocean acidification impacts fish and other marine species through increased seawater PCO2 levels (hypercapnia). Knowledge of the physiological mechanisms mediating effects in various tissues of fish is incomplete. Here we tested the effects of extracellular hypercapnia and acidosis on energy metabolism of gill and liver cells of Atlantic cod. Exposure media mimicked blood conditions in vivo, either during normo- or hypercapnia and at control or acidic extracellular pH (pHe). We determined metabolic rate and energy expenditure for protein biosynthesis, Na+/K+-ATPase and H+-ATPase and considered nutrition status by measurements of metabolic rate and protein biosynthesis in media with and without free amino acids (FAA). Addition of FAA stimulated hepatic but not branchial oxygen consumption. Normo- and hypercapnic acidosis as well as hypercapnia at control pHe depressed metabolic stimulation of hepatocytes. In gill cells, acidosis depressed respiration independent of PCO2 and FAA levels. For both cell types, depressed respiration was not correlated with the same reduction in energy allocated to protein biosynthesis or Na+/K+-ATPase. Hepatic energy expenditure for protein synthesis and Na+/K+-ATPase was even elevated at acidic compared to control pHe suggesting increased costs for ion regulation and cellular reorganization. Hypercapnia at control pHe strongly reduced oxygen demand of branchial Na+/K+-ATPase with a similar trend for H+-ATPase. We conclude that extracellular acidosis triggers metabolic depression in gill and metabolically stimulated liver cells. Additionally, hypercapnia itself seems to limit capacities for metabolic usage of amino acids in liver cells while it decreases the use and costs of ion regulatory ATPases in gill cells.


      PubDate: 2015-07-14T01:05:00Z
       
  • Expression analysis of HSP70 in the testis of Octopus tankahkeei under
           thermal stress
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Ling-Li Long , Ying-Li Han , Zhang Sheng , Chen Du , You-Fa Wang , Jun-Quan Zhu
      The gene encoding heat shock protein 70 (HSP70) was identified in Octopus tankahkeei by homologous cloning and rapid amplification of cDNA ends (RACE). The full-length cDNA (2471bp) consists of a 5′-untranslated region (UTR) (89bp), a 3′-UTR (426bp), and an open reading frame (1956bp) that encodes 651 amino acid residues with a predicted molecular mass of 71.8kDa and an isoelectric point of 5.34. Based on the amino acid sequence analysis and multiple sequence alignment, this cDNA is a member of cytoplasmic hsp70 subfamily of the hsp70 family and was designated as ot-hsp70. Tissue expression analysis showed that HSP70 expression is highest in the testes when all examined organs were compared. Immunohistochemistry analysis, together with hematoxylin–eosin staining, revealed that the HSP70 protein was expressed in all spermatogenic cells, but not in fibroblasts. In addition, O. tankahkeei were heat challenged by exposure to 32°C seawater for 2h, then returned to 13°C for various recovery time (0–24h). Relative expression of ot-hsp70 mRNA in the testes was measured at different time points post-challenge by quantitative real-time PCR. A clear time-dependent mRNA expression of ot-hsp70 after thermal stress indicates that the HSP70 gene is inducible. Ultrastructural changes of the heat-stressed testis were observed by transmission electron microscopy. We suggest that HSP70 plays an important role in spermatogenesis and testis protection against thermal stress in O. tankahkeei.


      PubDate: 2015-07-14T01:05:00Z
       
  • Physiological condition of bank voles (Myodes glareolus) during the
           increase and decline phases of the population cycle
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Petteri Nieminen , Otso Huitu , Heikki Henttonen , Mikko A.J. Finnilä , Liina Voutilainen , Juhani Itämies , Vesa Kärjä , Seppo Saarela , Toivo Halonen , Jari Aho , Anne-Mari Mustonen
      The dynamics of animal populations are greatly influenced by interactions with their natural enemies and food resources. However, quantifying the relative effects of these factors on demographic rates remains a perpetual challenge for animal population ecology. Food scarcity is assumed to limit the growth and to initiate the decline of cyclic herbivore populations, but this has not been verified with physiological health indices. We hypothesized that individuals in declining populations would exhibit signs of malnutrition-induced deterioration of physiological condition. We evaluated the association of body condition with population cycle phase in bank voles (Myodes glareolus) during the increase and decline phases of a population cycle. The bank voles had lower body masses, condition indices and absolute masses of particular organs during the decline. Simultaneously, they had lower femoral masses, mineral contents and densities. Hemoglobin and hematocrit values and several parameters known to respond to food deprivation were unaffected by the population phase. There were no signs of lymphopenia, eosinophilia, granulocytosis or monocytosis. Erythrocyte counts were higher and plasma total protein levels and tissue proportions of essential polyunsaturated fatty acids lower in the population decline. Ectoparasite load was lower and adrenal gland masses or catecholamine concentrations did not suggest higher stress levels. Food availability seems to limit the size of voles during the decline but they can adapt to the prevailing conditions without clear deleterious health effects. This highlights the importance of quantifying individual health state when evaluating the effects of complex trophic interactions on the dynamics of wild animal populations.


      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
       
  • Control of cardiorespiratory function in response to hypoxia in an
           air-breathing fish, the African sharptooth catfish, Clarias gariepinus
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): T.C. Belão , V.M. Zeraik , L.H. Florindo , A.L. Kalinin , C.A.C. Leite , F.T. Rantin
      We evaluated the role of the first pair of gill arches in the control of cardiorespiratory responses to normoxia and hypoxia in the air-breathing catfish, Clarias gariepinus. An intact group (IG) and an experimental group (EG, bilateral excision of first gill arch) were submitted to graded hypoxia, with and without access to air. The first pair of gill arches ablations reduced respiratory surface area and removed innervation by cranial nerve IX. In graded hypoxia without access to air, both groups displayed bradycardia and increased ventilatory stroke volume (V T), and the IG showed a significant increase in breathing frequency (f R). The EG exhibited very high f R in normoxia that did not increase further in hypoxia, this was linked to reduced O2 extraction from the ventilatory current (EO2) and a significantly higher critical O2 tension (PcO2) than the IG. In hypoxia with access to air, only the IG showed increased air-breathing, indicating that the first pair of gill arches excision severely attenuated air-breathing responses. Both groups exhibited bradycardia before and tachycardia after air-breaths. The f H and gill ventilation amplitude (V AMP) in the EG were overall higher than the IG. External and internal NaCN injections revealed that O2 chemoreceptors mediating ventilatory hypoxic responses (f R and V T) are internally oriented. The NaCN injections indicated that f R responses were mediated by receptors predominantly in the first pair of gill arches but V T responses by receptors on all gill arches. Receptors eliciting cardiac responses were both internally and externally oriented and distributed on all gill arches or extra-branchially. Air-breathing responses were predominantly mediated by receptors in the first pair of gill arches. In conclusion, the role of the first pair of gill arches is related to: (a) an elevated EO2 providing an adequate O2 uptake to maintain the aerobic metabolism during normoxia; (b) a significant bradycardia and increased f AB elicited by externally oriented O2 chemoreceptors; (c) increase in the ventilatory variables (f R and V AMP) stimulated by internally oriented O2 chemoreceptors.


      PubDate: 2015-07-14T01:05:00Z
       
  • The digestive morphophysiology of wild, free-living, giraffes
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): G. Mitchell , D.G. Roberts , S.J. van Sittert
      We have measured rumen-complex (rumen, reticulum, omasum, abomasum) and intestine (small and large combined) mass in 32 wild giraffes of both sexes with body masses ranging from 289 to 1441kg, and parotid gland mass, tongue length and mass, masseter and mandible mass in 9 other giraffes ranging in body mass from 181 to 1396kg. We have estimated metabolic and energy production rates, feed intake and home range size. Interspecific analysis of mature ruminants show that components of the digestive system increase linearly (Mb1) or positively allometric (Mb>1) with body mass while variables associated with feed intake scale with metabolic rate (Mb.75). Conversely, in giraffes ontogenetic increases in rumen-complex mass were negatively allometric (Mb<1), and increases in intestine mass, parotid gland mass, masseter mass, and mandible mass were isometric (Mb1). The relative masseter muscle mass (0.14% of Mb) and the relative parotid mass (0.03% of Mb) are smaller than in other ruminants. Increases in tongue length scale with head length0.72 and Mb.32 and tongue mass with Mb.69. Absolute mass of the gastrointestinal tract increased throughout growth but its relative mass declined from 20% to 15% of Mb. Rumen-complex fermentation provides ca 43% of daily energy needs, large intestine fermentation 24% and 33% by digestion of soluble carbohydrates, proteins, and lipids. Dry matter intake (kg) was 2.4% of body mass in juveniles and 1.6% in adults. Energy requirements increased from 35Mj/day to 190Mj/day. Browse production rate sustains a core home range of 2.2–11.8km2.


      PubDate: 2015-07-14T01:05:00Z
       
  • In vivo and in vitro effects of high-K+ stress on branchial expression of
           ROMKa in seawater-acclimated Mozambique tilapia
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Fumiya Furukawa , Soichi Watanabe , Andre P. Seale , Jason P. Breves , Darren T. Lerner , E. Gordon Grau , Toyoji Kaneko
      Recently, a teleost ortholog of renal outer medullary K+ channel (ROMK) expressed in gill ionocytes (ROMKa) has emerged as a primary K+-excreting pathway in fish. However, the mechanisms by which ROMKa expression is regulated in response to perturbations of plasma K+ levels are unknown. In this study, we aimed to identify potential links between the endocrine system and K+ regulation in a euryhaline fish. We assessed time-course changes in multiple endocrine parameters, including plasma cortisol and gene expression of branchial glucocorticoid and mineralocorticoid receptors (GR1, GR2, and MR) and pituitary hormones, in seawater (SW)-acclimated Mozambique tilapia (Oreochromis mossambicus) exposed to high-K+ (H-K) SW. Exposure to H-K SW elicited little effects on plasma cortisol or mRNA levels of GRs and pituitary hormones. Since plasma K+ and branchial ROMKa expression was increased within 6h after H-K treatment in vivo, the effect of high K+ was subsequently tested in a gill filament incubation experiment using media with differing K+ concentrations. ROMKa mRNA levels were induced following incubation of filaments in H-K medium for 6h. The present study is the first to demonstrate that the expression of ROMKa in teleost ionocytes can respond to high K+ conditions independent from systemic signaling.


      PubDate: 2015-07-14T01:05:00Z
       
  • Comparative ventilatory strategies of acclimated rats and burrowing
           plateau pika (Ochotona curzoniae) in response to hypoxic–hypercapnia
           
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Aurélien Pichon , Nicolas Voituron , Zhenzhong Bai , Florine Jeton , Wuren Tana , Dominique Marchant , Guoen Jin , Jean-Paul Richalet , Ri-Li Ge
      The objective of this study was to compare the different ventilatory strategies that help in coping with hypoxic–hypercapnia environment among two species: use acclimated rats and plateau pikas (Ochotona curzoniae) that live in Tibetan plateaus, and have been well adjusted to high altitude. Arterial blood samples taken at 4100m of elevation in acclimatized rats and adapted pikas revealed inter-species differences with lower hemoglobin and hematocrit and higher blood pH in pikas. A linear and significant increase in minute ventilation was observed in pikas, which help them to cope with hypoxic–hypercapnia. Pikas also displayed a high inspiratory drive and an invariant respiratory timing regardless of the conditions. Biochemical analysis revealed that N-methyl-D-aspartate receptor (NMDA) receptor gene and nNOS gene are highly conserved between rats and pikas, however pikas have higher expression of NMDA receptors and nNOS compared to rats at the brainstem level. Taken together, these results suggest that pikas have developed a specific ventilatory pattern supported by a modification of the NMDA/NO ventilatory central pathways to survive in extreme conditions imposed on the Tibetan plateaus. These physiological adaptive strategies help in maintaining a better blood oxygenation despite high CO2 concentration in burrows at high altitude.


      PubDate: 2015-07-14T01:05:00Z
       
  • Is winter worse for stressed fish' The consequences of exogenous
           cortisol manipulation on over-winter survival and condition of juvenile
           largemouth bass
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Thomas R. Binder , Constance M. O'Connor , Sarah H. McConnachie , Samantha M. Wilson , Michael A. Nannini , David H. Wahl , Steven J. Cooke
      Over-winter mortality is an important selective force for warm-water fish (e.g., centrarchids) that live in temperate habitats. Inherent challenges faced by fish during winter may be compounded by additional stressors that activate the hypothalamic–pituitary–interrenal axis, either before or during winter, leading to negative sub-lethal impacts on fish health and condition, and possibly reducing chance of survival. We used experimental cortisol manipulation to test the hypothesis that juvenile largemouth bass (Micropterus salmoides) exposed to semi-chronic elevation in cortisol prior to winter would experience higher levels of over-winter mortality, physiological alterations and impaired immune status relative to control and sham-treated bass. Over-winter survival in experimental ponds was high, averaging 83%, and did not differ among treatment groups. Over the study period, bass exhibited an average increase in mass of 19.4%, as well as a slight increase in Fulton's condition factor, but neither measure differed among groups. Hepatosomatic index in cortisol-treated bass was 23% lower than in control fish, suggesting lower energy status, but white muscle lipid content was similar across all groups. Lastly, there was no difference in spleen somatic index or parasite load among treatment groups, indicating no long-term immune impairment related to our cortisol manipulation. The current study adds to a growing body of literature on glucocorticoid manipulations where field-based findings are not consistent with laboratory-based conceptual understanding of multiple stressors. This suggests that field conditions may provide fish with opportunities to mitigate negative effects of some stressors.


      PubDate: 2015-07-14T01:05:00Z
       
  • Transport characteristics and morphology of the colon and coprodeum in two
           wild birds of different habitats, the rock ptarmigan (Lagopus mutus) and
           the common murre (Uria aalge)
    • Abstract: Publication date: September 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 187
      Author(s): Sighvatur S. Árnason , Vibeke S. Elbrønd , Gary Laverty
      Dietary salt intake in domestic fowl affects epithelial transport and morphology of the lower intestine (colon and coprodeum). This study investigated lower intestinal morphology and transport activity in two wild bird species with natural diets containing either low or high salt. Tissues from rock ptarmigan (Lagopus mutus) and common murres (Uria aalge) were sampled for histology and electrophysiological analyses. The ptarmigan exists on a low salt diet, while the murre lives on a high protein and high salt diet. The ptarmigan colon and coprodeum had villi/folds and crypts and the epithelium contained absorptive epithelial cells, mitochondria-rich cells and goblet cells. The colon had significant amiloride-inhibitable Isc, 5-15μA/cm2, with no glucose-stimulated Isc, and no significant phloridzin inhibition. The coprodeum also had high amiloride-inhibitable Isc. This transport pattern corresponded to that of chickens on low-salt diets. However, the ptarmigan colon also had a significant lysine/leucine-stimulated Isc of 3±1.0μA/cm2. The short U. aalge colon was similar to that of ptarmigans, but with no villi. It demonstrated a significant lysine/leucine-stimulated Isc (11±3.5μA/cm2) with no amiloride-inhibitable Isc, similar to the high-salt chicken colon, but with no Na+-glucose cotransport. The murre coprodeum was inert to all substances and showed high resistance (1000Ω·cm2), with a multilayered squamous epithelium. Despite some variations possibly associated with dietary protein intake, we conclude that natural high and low salt diets in different avian species are associated with different lower intestinal transport patterns, providing for post-renal adjustments in ion and water excretion.


      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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