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BIOCHEMISTRY (230 journals)                  1 2     

Showing 1 - 0 of 0 Journals sorted alphabetically
AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Central Science     Open Access   (Followers: 6)
ACS Chemical Biology     Full-text available via subscription   (Followers: 206)
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: 7)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9)
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: 17)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
American Journal of Biochemistry     Open Access   (Followers: 7)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 65)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 14)
American Journal of Polymer Science     Open Access   (Followers: 23)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical Biochemistry     Hybrid Journal   (Followers: 148)
Angiogenesis     Hybrid Journal   (Followers: 3)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 53)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 45)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 6)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 21)
Archives of Insect Biochemistry and Physiology     Hybrid Journal  
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
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: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 19)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 4)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 15)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 26)
Biochemical Pharmacology     Hybrid Journal   (Followers: 9)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 4)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 3)
Biochemistry     Full-text available via subscription   (Followers: 254)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 3)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Biophysics Reports     Open Access  
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 14)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 5)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 6)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 8)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 6)
Biochimie     Hybrid Journal   (Followers: 7)
Biochimie Open     Open Access  
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 30)
BioDrugs     Full-text available via subscription   (Followers: 8)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofuels     Hybrid Journal   (Followers: 10)
Biogeochemistry     Hybrid Journal   (Followers: 12)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 24)
Biomaterials Research     Open Access   (Followers: 4)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 24)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 45)
Bitácora Digital     Open Access  
BMC Biochemistry     Open Access   (Followers: 14)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 5)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 6)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
ChemBioChem     Hybrid Journal   (Followers: 6)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 22)
Chemical Engineering Journal     Hybrid Journal   (Followers: 32)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
Chemistry and Ecology     Hybrid Journal  
ChemTexts     Hybrid Journal  
Clinica Chimica Acta     Hybrid Journal   (Followers: 36)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 19)
Clinical Chemistry     Full-text available via subscription   (Followers: 67)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 60)
Clinical Lipidology     Full-text available via subscription   (Followers: 1)
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 7)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 3)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 5)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Medicinal Chemistry     Hybrid Journal   (Followers: 15)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 25)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 6)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (Followers: 1)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
FABICIB     Open Access  
FEBS Letters     Hybrid Journal   (Followers: 60)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 4)
Food & Function     Full-text available via subscription   (Followers: 5)
Foundations of Modern Biochemistry     Full-text available via subscription  
Free Radicals and Antioxidants     Full-text available via subscription   (Followers: 4)
Frontiers in Molecular Biosciences     Open Access   (Followers: 2)
Frontiers in Natural Product Chemistry     Hybrid Journal  
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 12)
Green Chemistry     Full-text available via subscription   (Followers: 9)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 4)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 3)
Indian Journal of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Indonesian Biomedical Journal     Open Access  
Insect Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3)
International Journal of Biochemistry & Cell Biology     Hybrid Journal   (Followers: 7)
International Journal of Biochemistry and Biophysics     Open Access   (Followers: 1)
International Journal of Biological Chemistry     Open Access   (Followers: 4)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 6)
International Journal of Food Contamination     Open Access  
International Journal of Plant Physiology and Biochemistry     Open Access  
International Journal of Plant Research     Open Access   (Followers: 3)
International Journal of Secondary Metabolite     Open Access   (Followers: 1)
Invertebrate Immunity     Open Access   (Followers: 1)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 5)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 2)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 2)
Journal of Bioactive and Compatible Polymers     Hybrid Journal   (Followers: 2)
Journal of Biochemistry     Hybrid Journal   (Followers: 43)
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 186)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 7)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Chemical Biology     Hybrid Journal   (Followers: 1)
Journal of Chemical Neuroanatomy     Hybrid Journal  
Journal of Clinical Lipidology     Hybrid Journal   (Followers: 1)
Journal of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology     Hybrid Journal   (Followers: 4)
Journal of Drug Discovery and Therapeutics     Open Access  
Journal of Enzyme Inhibition and Medicinal Chemistry     Hybrid Journal   (Followers: 3)
Journal of Evolutionary Biochemistry and Physiology     Hybrid Journal  
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 3)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 6)
Journal of Investigational Biochemistry     Open Access   (Followers: 2)
Journal of Medical and Biomedical Sciences     Open Access  
Journal of Medical Biochemistry     Open Access   (Followers: 4)
Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
Journal of Molecular Biochemistry     Open Access   (Followers: 3)
Journal of Molecular Diagnostics     Hybrid Journal   (Followers: 7)
Journal of Neurochemistry     Hybrid Journal   (Followers: 3)
Journal of Nutritional Biochemistry     Hybrid Journal   (Followers: 7)
Journal of Pediatric Biochemistry     Hybrid Journal   (Followers: 1)
Journal of Peptide Science     Hybrid Journal   (Followers: 23)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 1)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 5)
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 4)
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 7)
La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine     Hybrid Journal  
Lab on a Chip     Full-text available via subscription   (Followers: 35)
Marine Chemistry     Hybrid Journal   (Followers: 6)
Methods in Enzymology     Full-text available via subscription   (Followers: 11)
Molecular and Biochemical Parasitology     Hybrid Journal   (Followers: 2)
Molecular and Cellular Biochemistry     Hybrid Journal   (Followers: 4)
Molecular Aspects of Medicine     Hybrid Journal   (Followers: 4)
Molecular Informatics     Hybrid Journal   (Followers: 4)
Molecular inhibitors in targeted therapy     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
Mycology : An International Journal on Fungal Biology     Hybrid Journal   (Followers: 6)
Natural Products and Bioprospecting     Open Access   (Followers: 3)
Nature Chemical Biology     Full-text available via subscription   (Followers: 72)
Nature Communications     Open Access   (Followers: 140)
Neurosignals     Open Access  
Novelty in Biomedicine     Open Access  
Ocean Acidification     Open Access   (Followers: 3)
Organic & Biomolecular Chemistry     Full-text available via subscription   (Followers: 90)
Peptidomics     Open Access  
Pesticide Biochemistry and Physiology     Hybrid Journal   (Followers: 4)
Pflugers Archiv European Journal of Physiology     Hybrid Journal   (Followers: 3)
Pharmaceutical Bioprocessing     Full-text available via subscription   (Followers: 1)
Pharmacognosy Magazine     Open Access   (Followers: 2)

        1 2     

Journal Cover Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [SJR: 0.939]   [H-I: 84]   [5 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [3039 journals]
  • Nuclear and membrane progestin receptors in the European eel:
           characterization and expression in vivo through spermatogenesis
    • Abstract: Publication date: Available online 11 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marina Morini, David S. Peñaranda, María C. Vílchez, Rasoul Nourizadeh-Lillabadi, Anne-Gaëlle Lafont, Sylvie Dufour, Juan F. Asturiano, Finn-Arne Weltzien, Luz Pérez
      Characterization of all the progestin receptor genes (PRs) found in the European eel has been performed. There were five membrane PRs (mPRs): mPRα (alpha), mPRAL1 (alpha-like1), mPRAL2 (alpha-like2), mPRγ (gamma), mPRδ (delta) and two nuclear PRs (nPRs or PGRs): pgr1 and pgr2. In silico studies showed that the C and E(F) domains of Pgr are well conserved among vertebrates whereas the A/B domain is not. Phylogeny and synteny analyses suggest that eel duplicated pgr (pgr1 and pgr2) originated from the teleost-specific third whole genome duplication (3R). mPR phylogeny placed three eel mPRs together with the mPRα clade, being termed mPRα, mPRAL1 and mPRAL2, while the other two eel mPRs clustered with mPRγ and mPRδ clades, respectively. The in vivo study showed differential expression patterns along the brain-pituitary-gonad axis. An increase in nPR transcripts was observed in brain (in pgr1) and pituitary (in pgr1 and pgr2) through the spermatogenesis, from the spermatogonia B/spermatocyte stage to the spermiation stage. In the testis, mPRγ, mPRδ and pgr2 transcripts showed the highest levels in testis with A spermatogonia as dominant germ cell, while the highest mPRα, mPRAL1 and mPRAL2 transcripts were observed in testis from spermiating males, where the dominant germ cell were spermatozoa. Further studies should elucidate the role of both nuclear and membrane progestin receptors on eel spermatogenesis.

      PubDate: 2017-02-17T01:17:39Z
  • Molecular cloning, mRNA expression and characterization of membrane-bound
           hemoglobin in oriental river prawn Macrobrachium nipponense
    • Abstract: Publication date: Available online 10 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Shengming Sun, Fujun Xuan, Hongtuo Fu, Jian Zhu, Xianping Ge, Xugan Wu
      Most hemoglobins are respiratory proteins and are ubiquitous in animals, bacteria, fungi, protists, and plants. In this study, we describe a membrane-bound hemoglobin in the oriental river prawn Macrobrachium nipponense (MnHb), which also expresses hemocyanin. MnHb cDNA was cloned using the rapid amplification of cDNA ends (RACE) approach, which afforded a 1201bp gene encoding a 193 amino acid polypeptide. Bioinformatic evaluation suggested MnHb is membrane anchored by N-myristoylation, and immunofluorescence confirmed its location in the membrane of chief cells in the gill. The effect of hypoxia on MnHb expression was investigated, and reverse transcription PCR (RT-PCR) and Western blotting showed that MnHb was expressed almost exclusively in the gill. Quantitative RT-PCR revealed a significant increase in expression after 6h of hypoxia, and levels peaked at 24h due to oxidative stress. Exposure of cultured prawns to the stress inducer H2O2 significantly up-regulated the expression of MnHb in a dose-dependent manner. MnHb may have a role in protecting cell membrane lipids from damage by reactive oxygen species.

      PubDate: 2017-02-11T00:09:51Z
  • Molecular cloning, characterization, and temporal expression of the clock
           genes period and timeless in the oriental river prawn Macrobrachium
           nipponense during female reproductive development
    • Abstract: Publication date: Available online 10 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): SuHua Chen, Hui Qiao, HongTuo Fu, Shengming Sun, WenYi Zhang, ShuBo Jin, Yongsheng Gong, Sufei Jiang, Weiyi Xiong, YanWu
      The circadian clock is crucial for sustaining rhythmic biochemical, physiological, and behavioral processes in living creatures. In this study, we isolated and characterized two circadian clock genes in Macrobrachium nipponense, period (Mnper) and timeless (Mntim). The complete Mnper cDNA measures 4283bp in length with an open reading frame encoding 1292 amino acids, including functional domains such as PER-ARNT-SIM (PAS), cytoplasmic localization domain (CLD), TIM interaction site (TIS), and nuclear localization signal (NLS). The deduced Mntim protein comprises1540 amino acids with functional domains such as PER interaction site (PIS), NLS, and CLD. Tissue distribution analyses showed that the two genes were highly expressed in the eyestalk and brain in both males and females, as well as being expressed in the ovary. The expression profiles of Mnper and Mntim were determined in the eyestalk, brain, and ovary under simulated breeding season and non-breeding season conditions. The expression profiles of both Mnper and Mntim appeared to be unaffected in the eyestalk. However, the expression of both genes exhibited significant seasonal variations in the brain, and thus we assumed the brain to be their functional location. The expression profiles under different simulated seasons and the variations during different ovarian stages indicate that both genes might be involved with female reproduction. Especially the mRNA levels in the brain varied greatly during these stages indicating that the clock function in the brain is closely related to ovarian development and female reproduction. And the reproductive roles of clock genes need to be elucidated.

      PubDate: 2017-02-11T00:09:51Z
  • The influence of mechanical ventilation on physiological parameters in
           ball pythons (Python regius)
    • Abstract: Publication date: Available online 10 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sashia L. Jakobsen, Catherine J.A. Williams, Tobias Wang, Mads F. Bertelsen
      Mechanical ventilation is widely recommended for reptiles during anesthesia, and while it is well-known that their low ectothermic metabolism requires much lower ventilation than in mammals, very little is known about the influence of ventilation protocol on the recovery from anesthesia. Here, 15 ball pythons (Python regius) were induced and maintained with isoflurane for 60min at one of three ventilation protocols (30, 125, or 250ml min−1 kg−1 body mass) while an arterial catheter was inserted, and ventilation was then continued on 100% oxygen at the specified rate until voluntary extubation. Mean arterial blood pressure and heart rate (HR) were measured, and arterial blood samples collected at 60, 80, 180min and 12 and 24h after intubation. In all three groups, there was evidence of a metabolic acidosis, and snakes maintained at 30ml min−1 kg−1 experienced an additional respiratory acidosis, while the two other ventilation protocols resulted in normal or low arterial PCO2. In general, normal acid-base status was restored within 12h in all three protocols. HR increased by 143±64% during anesthesia with high mechanical ventilation (250ml/min/kg) in comparison with recovered values. Recovery times after mechanical ventilation at 30, 125, or 250ml min−1 kg−1 were 289±70, 126±16, and 68±7min, respectively. Mild overventilation may result in a faster recovery, and the associated lowering of arterial PCO2 normalised arterial pH in the face of metabolic acidosis.

      PubDate: 2017-02-11T00:09:51Z
  • Effects of pinealectomy on the neuroendocrine reproductive system and
           locomotor activity in male European sea bass, Dicentrarchus labrax
    • Abstract: Publication date: Available online 8 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mairi Cowan, José A. Paullada-Salmerón, José Fernando López-Olmeda, Francisco Javier Sánchez-Vázquez, José A. Muñoz-Cueto
      The seasonally changing photoperiod controls the timing of reproduction in most fish species, however, the transduction of this photoperiodic information to the reproductive axis is still unclear. This study explored the potential role of two candidate neuropeptide systems, gonadotropin-inhibitory hormone (Gnih) and kisspeptin, as mediators between the pineal organ (a principle transducer of photoperiodic information) and reproductive axis in male European sea bass, Dicentrarchus labrax. Two seven-day experiments of pinealectomy (Px) were performed, in March (end of reproductive season) and August (resting season). Effects of Px and season on the brain expression of gnih (sbgnih) and its receptor (sbgnihr), kisspeptins (kiss1, kiss2) and their receptors (kissr2, kissr3) and gonadotropin-releasing hormone (gnrh1, gnrh2, gnrh3) and the main brain receptor (gnrhr-II-2b) genes, plasma melatonin levels and locomotor activity rhythms were examined. Results showed that Px reduced night-time plasma melatonin levels. Gene expression analyses demonstrated a sensitivity of the Gnih system to Px in March, with a reduction in sbgnih in the mid-hindbrain, a region with bilateral connections to the pineal organ. In August, kiss2 levels increased in Px animals but not in controls. Significant differences in expression were observed for diencephalic sbgnih, sbgnihr, kissr3 and tegmental gnrh2 between seasons. Recordings of locomotor activity following surgery revealed a change from light-synchronised to free-running rhythmic behavior. Altogether, the Gnih and Kiss2 sensitivity to Px and seasonal differences observed for Gnih and its receptor, Gnrh2, and the receptor for Kiss2 (Kissr3), suggested they could be mediators involved in the relay between environment and seasonal reproduction.

      PubDate: 2017-02-11T00:09:51Z
  • An experimental evaluation of the role of the stress axis in mediating
           predator-prey interactions in wild marine fish
    • Abstract: Publication date: Available online 7 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Michael J. Lawrence, Erika J. Eliason, Jacob W. Brownscombe, Kathleen M. Gilmour, John W. Mandelman, Steven J. Cooke
      The hypothalamic-pituitary-interrenal (HPI) axis, through corticosteroid secretion, is an integral mechanism regulating internal homeostasis when vertebrates are faced with a stressor. However, continued HPI-axis stimulation can produce homeostatic overload, where corticosteroids are detrimental to organismal function. This overload condition may play an important role in mediating predator-prey interactions, because chronically/previously stressed animals may have higher rates of predator-induced mortality. However, the mechanism(s) underlying this observation are unknown. Using fish as models, we hypothesized that chronic stress would increase predation susceptibility owing to a poor physiological state (e.g. homeostatic overload) with corresponding sub-optimal changes in predator-avoidance behaviour. As cortisol is also required in low quantities to help regulate basic metabolic functions in fish, we expected that a glucocorticoid receptor antagonist (GR; e.g. homeostatic failure) may produce similar effects. Schoolmaster snapper (Lutjanus apodus) were given intraperitoneal implants of cocoa butter impregnated with nothing (sham; 5ml/kg body weight (BW)), cortisol (50mg/kg BW) or the GR antagonist RU486 (100mg/kg BW). At 24-h post-implantation, fish were tethered to the seafloor and observed for behavioural metrics associated with predation. Blood samples were collected from a subset of fish to assess the physiological consequences of the implants. Cortisol- and RU486-implanted fish both had significantly higher plasma cortisol concentrations than sham fish, with blood glucose and plasma urea being elevated only in the former. Further, anti-predator behaviours and predation mortality did not differ significantly among treatments. Despite changes in physiological state, predation susceptibility was unaffected, a finding that may reflect the complex relationships linking the physiology and behaviour of an organism as well as potential tethering artefacts.

      PubDate: 2017-02-11T00:09:51Z
  • Temperature dependent growth, feeding, nutritional condition and aerobic
           metabolism of juvenile spiny lobster, Sagmariasus verreauxi
    • Abstract: Publication date: Available online 5 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Quinn P. Fitzgibbon, Cedric J. Simon, Gregory G. Smith, Chris G. Carter, Stephen C. Battaglene
      We examined the effects of temperature on the growth, feeding, nutritional condition and aerobic metabolism of juvenile spiny lobster, Sagmariasus verreauxi, in order to determine if temperature acclimated aerobic scope correlates with optimum for growth and to establish the thermal tolerance window for this emerging aquaculture species. Juvenile lobsters (initial weight=10.95±0.47g) were reared (n =7) at temperatures from 11.0 to 28.5°C for 145days. All lobsters survived from 14.5 to 25.0°C while survival was reduced at 11.0°C (86%) and all lobsters died at 28.5°C. Lobster specific growth rate and specific feed consumption displayed a unimodal response with temperature peaking at 21.5°C. Lobster standard, routine and maximum metabolic rates, and aerobic scope all increased exponentially up to maximum non-lethal temperature. Optimum temperature for growth did not correspond to that for maximum aerobic scope suggesting that aerobic scope is not an effective predictor of the thermal optimum of spiny lobsters. Plateauing of specific feed consumption beyond 21.5°C suggests that temperature dependent growth of lobsters is limited by capacity to ingest or digest sufficient food to meet increasing maintenance metabolic demands at high temperatures. The nutritional condition of lobsters was not influenced by temperature and feed conversion ratio was improved at lower temperatures. These findings add to a growing body of evidence questioning the generality of aerobic scope to describe the physiological thermal boundaries of aquatic ectotherms and suggest that feed intake plays a crucial role in regulating performance at thermal extremes.

      PubDate: 2017-02-11T00:09:51Z
  • Understanding evolutionary variation in basal metabolic rate: an analysis
           in subterranean rodents
    • Abstract: Publication date: Available online 4 February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Facundo Luna, Hugo Naya, Daniel E. Naya
      Understanding how evolutionary variation in energetic metabolism arises is central to several theories in animal biology. Basal metabolic rate (BMR) –i.e., the minimum rate of energy necessary to maintain thermal homeostasis in endotherms– is a highly informative measure to increase our understanding, because it is determined under highly standardized conditions. In this study we evaluate the relationship between taxa- and mass-independent (residual) BMR and ten environmental factors for 34 subterranean rodent species. Both conventional and phylogenetically informed analyses indicate that ambient temperature is the major determinant of residual BMR, with both variables inversely correlated. By contrast, other environmental factors that have been shown to affect residual BMR in endotherms, such as habitat productivity and rainfall, were not significant predictors of residual BMR in this group of species. Then, the results for subterranean rodents appear to support a central prediction of the obligatory heat model (OHM), which is a mechanistic model aimed to explain the evolution of residual BMR. Specifically, OHM proposes that during the colonization of colder environments, individuals with greater masses of metabolically expensive tissues (and thus with greater BMR) are favored by natural selection due to the link between greater masses of metabolically expensive tissues and physiological capacities. This way, natural selection should establishes a negative correlation between ambient temperature and both internal organ size and residual BMR.

      PubDate: 2017-02-04T23:14:40Z
  • Identification of the putative goldfish (Carassius auratus) magnesium
           transporter SLC41a1 and functional regulation in the gill, kidney, and
           intestine in response to dietary and environmental manipulations
    • Abstract: Publication date: Available online 24 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Vladimir Kodzhahinchev, Drago Kovacevic, Carol Bucking
      While magnesium requirements for teleost fish highlight the physiological importance of this cation for homeostasis, little is known regarding the molecular identity of transporters responsible for magnesium absorption or secretion. The recent characterization of the vertebrate magnesium transporter solute carrier 41a1 (SLC41a1) in the kidney of a euryhaline fish has provided a glimpse of possible moieties involved in piscine magnesium regulation. The present study obtained a novel SLC41a1 coding sequence for Carassius auratus and demonstrated ubiquitous expression in all tissues examined. Transcriptional regulation of SLC41a1 in response to dietary and environmental magnesium concentrations was observed across tissues. Specifically, decreased environmental magnesium correlated with decreased expression of SLC41a1 in the intestine, whereas the gill and kidney were unaffected. Dietary magnesium restriction correlated with decreased expression of SLC41a1 in the intestine and gill, while again no effects were detected in the kidney. Finally, elevated dietary magnesium correlated with increased expression of SLC41a1 in the kidney, while expression in the intestine and gill remained stable. Plasma magnesium was maintained in all treatments, and dietary assimilation efficiency increased with decreased dietary magnesium. Consumption of a single meal failed to impact SLC41a1 expression, and transcript abundance remained stable over the course of digestion in all treatments. Transcriptional regulation occurred between 7 and 14days following dietary and environmental manipulations and short-term regulation (e.g. <24h) was not observed. Overall the data supports transcriptional regulation of SLC41a1 reflecting a possible role in magnesium loss or secretion across tissues in fish.

      PubDate: 2017-01-29T22:40:01Z
  • An energetic perspective on tissue regeneration: The costs of tail
           autotomy in growing geckos
    • Abstract: Publication date: Available online 24 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Zuzana Starostová, Lumír Gvoždík, Lukáš Kratochvíl
      Tail autotomy is a crucial antipredatory lizard response, which greatly increases individual survival, but at the same time also compromises locomotor performance, sacrifices energy stores and induces a higher burden due to the ensuing response of regenerating the lost body part. The potential costs of tail autotomy include shifts in energy allocation and metabolic rates, especially in juveniles, which invest their energy primarily in somatic growth. We compared the metabolic rates and followed the growth of juvenile males with and without regenerating tails in the Madagascar ground gecko (Paroedura picta), a nocturnal ground-dwelling lizard. Geckos with intact tails and those that were regrowing them grew in snout-vent-length at similar rates for 22weeks after autotomy. Tail regeneration had a negligible influence on body mass-corrected metabolic rate measured at regular intervals throughout the regenerative process. We conclude that fast-growing juveniles under the conditions of unrestricted food can largely compensate for costs of tail loss and regeneration in their somatic growth without a significant impact on the total individual body mass-corrected metabolic rate.

      PubDate: 2017-01-29T22:40:01Z
  • Interspecific variation and plasticity in hemoglobin nitrite reductase
           activity and its correlation with oxygen affinity in vertebrates
    • Abstract: Publication date: Available online 18 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Frank B. Jensen, Rasmus A.H. Kolind, Natashia S. Jensen, Gabriella Montesanti, Tobias Wang
      Deoxygenated hemoglobin (Hb) is a nitrite reductase that reduces naturally occurring nitrite to nitric oxide (NO), supplying physiological relevant NO under hypoxic conditions. The nitrite reductase activity is modulated by the allosteric equilibrium between the R and T structures of Hb that also determines oxygen affinity. In the present study we investigated nitrite reductase activity and O2 affinity in Hbs from ten different vertebrate species under identical conditions to disclose interspecific variations and allow an extended test for a correlation between the rate constant for nitrite reduction and O2 affinity. We also tested plastic changes in Hb properties via addition of T-structure-stabilizing organic phosphates (ATP and GTP). The decay in deoxyHb during its reaction with nitrite was exponential-like in ectotherms (Atlantic hagfish, carp, crucian carp, brown trout, rainbow trout, cane toad, Indian python and red-eared slider turtle), while it was sigmoid in mammals (harbor porpoise and rabbit). Typically, hypoxia-tolerant species showed a faster reaction than intolerant species. Addition of ATP and GTP decreased O2 affinity and slowed the rate of nitrite reduction in a concentration-dependent manner. The initial second order rate constant of the deoxyHb-mediated nitrite reduction showed a strong curvilinear correlation with oxygen affinity among all ectothermic vertebrates, and the relationship also applied to plastic variations of Hb properties via organic phosphates. The relationship predicts high nitrite reductase activity in hypoxic tolerant species with high Hb-O2 affinity and reveals that the decrease in erythrocyte ATP and/or GTP during acclimation to hypoxia in ectotherms increases the erythrocyte NO generating capacity.

      PubDate: 2017-01-22T22:01:26Z
  • Ex utero Culture of Viviparous Embryos of the Lizard, Zootoca vivipara,
           Provides Insights into Calcium Homeostasis during Development
    • Abstract: Publication date: Available online 18 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Tom W. Ecay, James R. Stewart, Greg Wiessner, Benoit Heulin
      The chorioallantoic membrane resides adjacent to either the inner surface of the egg shell or uterine epithelium in oviparous and viviparous reptiles, respectively. Chorionic cells face the shell or uterine epithelium and transport calcium to underlying embryonic capillaries. Calcium transport activity of the chorioallantois increases in the final stages of development coincident with rapid embryonic growth and skeletal ossification. We excised embryos from viviparous Zootoca vivipara females at a stage prior to significant calcium accumulation and incubated them ex utero with and without calcium to test the hypothesis that chorioallantois calcium transport activity depends on developmental stage and not calcium availability. We measured calcium uptake by monitoring incubation media calcium content and chorioallantois expression of calbindin-D28K, a marker for transcellular calcium transport. The pattern of calcium flux to the media differed by incubation condition. Eggs in 0mM calcium exhibited little variation in calcium gain or loss. For eggs in 2mM calcium, calcium flux to the media was highly variable and was directed inward during the last 3days of the experiment such that embryos gained calcium. Calbindin-D28K expression increased under both incubation conditions but was significantly higher in embryos incubated with 2mM calcium. We conclude that embryos respond to calcium availability, yet significant calcium accumulation is developmental stage dependent. These observations suggest the chorioallantois exhibits a degree of functional plasticity that facilitates response to metabolic or environmental fluctuations.

      PubDate: 2017-01-22T22:01:26Z
  • Developmental changes and day-night expression of the
           gonadotropin-inhibitory hormone system in the European sea bass: Effects
           of rearing temperature
    • Abstract: Publication date: Available online 18 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): José A. Paullada-Salmerón, Guillaume Henri Loentgen, Mairi Cowan, María Aliaga-Guerrero, María del Carmen Rendón-Unceta, José A. Muñoz-Cueto
      The role of rearing temperature on fish development, sex differentiation and puberty has been largely addressed, but the impact of water temperature on the ontogeny of the main neuroendocrine systems controlling reproduction has received little attention. Gonadotropin-inhibitory hormone (Gnih) has been shown to act on gonadotropin-releasing hormone (Gnrh) neurons and on the pituitary to inhibit gonadotropin release and synthesis in vertebrates, including sea bass, Dicentrarchus labrax. In the present study we investigated the effects of rearing temperature during the thermosensitive period (5–60days post-fertilization, dpf) on the expression of the Gnih gene (gnih) and its receptor (gnihr). Animals were maintained under two different conditions, low temperature (LT, 15°C) or high temperature (HT, 21°C), throughout the thermosensitive period and sampled from 5 to 360 dpf at mid-light (ML) and mid-dark (MD). Our results showed significant effects of temperature on gnih and gnihr expression during the thermosensitive period, with higher transcript levels under LT condition. Some differences were also evident after the completion of the sex differentiation process. Moreover, we revealed daily variations in the developmental expression of gnih and gnihr, with higher diurnal mRNA levels at early stages (until 25 dpf), and a shift to higher nocturnal expression levels at 300–360 dpf, which corresponded with the beginning of the winter (reproductive season). To the best of our knowledge, this work represents the first study reporting the effects of rearing temperature on the transcription of Gnih system genes, as well as its daily variations during the development of a fish species.

      PubDate: 2017-01-22T22:01:26Z
  • Dual estrogenic regulation of the nuclear progestin receptor and
           spermatogonial renewal during gilthead seabream (Sparus aurata)
    • Abstract: Publication date: Available online 15 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): François Chauvigné, Janmejay Parhi, Judith Ollé, Joan Cerdà
      Studies in teleosts suggest that progestins have crucial functions during early spermatogenesis. However, the role of the different progestin receptors in these mechanisms is poorly understood. In this work, we investigated the expression pattern and hormonal regulation of the classical nuclear progestin receptor (Pgr) in the gilthead seabream at three different stages of spermatogenesis: the resting (postspawning) phase, onset of spermatogenesis, and spermiation. Immunolocalization experiments using a seabream specific Pgr antibody revealed that the receptor was expressed in Sertoli and Leydig cells, and also in a subset of spermatogonia type A, throughout spermatogenesis. Short-term treatment of testis explants with 17β-estradiol (E2) increased pgr mRNA expression at all stages, while the progestin 17α,20β-dihydroxy-4-pregnen-3-one (17,20βP) had the opposite effect. At the resting stage, Sertoli cell Pgr expression was positively correlated with the occurrence of proliferating spermatogonia type A in the tubules, and both processes were incremented in vitro by E2 likely through the estrogen receptor alpha (Era) expressed in Sertoli and Leydig cells. In contrast, treatment with 17,20βP downregulated Pgr expression in somatic cells. The androgen 11-ketotestosterone (11-KT) upregulated pgr expression in Leydig cells and promoted the proliferation of mostly spermatogonia type B, but only during spermiation. No relationship between the changes in the cell type-specific expression of the Pgr with the entry into meiosis of germ cells was found. These data suggest a differential steroid regulation of Pgr expression during seabream spermatogenesis and the potential interplay of the E2/Era and 17,20βP/Pgr pathways for the maintenance of spermatogonial renewal rather than entry into meiosis.

      PubDate: 2017-01-15T19:05:24Z
  • Glucose, Amino Acids and Fatty Acids Directly Regulate Ghrelin and
           NUCB2/Nesfatin-1 in the Intestine and Hepatopancreas of Goldfish
           (Carassius auratus) In Vitro
    • Abstract: Publication date: Available online 13 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Juan Ignacio Bertucci, Ayelén Melisa Blanco, Luis Fabián Canosa, Suraj Unniappan
      Ghrelin and nesfatin-1 are two peptidyl hormones primarily involved in food intake regulation. We previously reported that the amount of dietary carbohydrates, protein and lipids modulates the expression of these peptides in goldfish in vivo. In the present work, we aimed to characterize the effects of single nutrients on ghrelin and nesfatin-1 in the intestine and hepatopancreas. First, immunolocalization of ghrelin and NUCB2/nesfatin-1 in goldfish hepatopancreas cells was studied by immunohistochemistry. Second, the effects of 2 and 4h-long exposures of cultured intestine and hepatopancreas sections to glucose, L-tryptophan, oleic acid, linolenic acid (LNA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on ghrelin and nesfatin-1 gene and protein expression were studied. Co-localization of ghrelin and NUCB2/nesfatin-1 in the cytoplasm of goldfish hepatocytes was found. Exposure to glucose led to an upregulation of preproghrelin and a downregulation of nucb2/nesfatin-1 in the intestine. L-tryptophan mainly decreased the expression of both peptides in intestine and hepatopancreas. All fatty acids in general downregulated NUCB2/nesfatin-1 in the intestine, but only the longer and highly unsaturated fatty acids inhibit preproghrelin. EPA exposure led to a decrease in preproghrelin, and an increase in nucb2/nesfatin-1 expression in hepatopancreas after 2h. These results show that macronutrients exert a dose- and time-dependent regulation of ghrelin and nesfatin-1 in intestine and hepatopancreas. This study indicates that macronutrients modulate ghrelin and NUCB2/nesfatin-1, and suggests a role for these hormones in the digestive process and nutrient metabolism.

      PubDate: 2017-01-15T19:05:24Z
  • Na+/K+-ATPase activity in the anoxic turtle (Trachemys scripta) brain at
           different acclimation temperature
    • Abstract: Publication date: Available online 13 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jonathan A.W. Stecyk, Anthony P. Farrell, Matti Vornanen
      Survival of prolonged anoxia requires a balance between cellular ATP demand and anaerobic ATP supply from glycolysis, especially in critical tissues such as the brain. To add insight into the ATP demand of the brain of the anoxia-tolerant red-eared slider turtle (Trachemys scripta) during prolonged periods of anoxic submergence, we quantified and compared the number of Na+-K+-ATPase units and their molecular activity in brain tissue from turtles acclimated to either 21°C or 5°C and exposed to either normoxia or anoxia (6h 21°C; 14 d at 5°C). Na+-K+-ATPase activity and density per g tissue were similar at 21°C and 5°C in normoxic turtles. Likewise, anoxia exposure at 21°C did not induce any change in Na+-K+-ATPase activity or density. In contrast, prolonged anoxia at 5°C significantly reduced Na+-K+-ATPase activity by 55%, which was largely driven by a 50% reduction of the number of Na+-K+-ATPase units without a change in the activity of existing Na+-K+-ATPase pumps or α-subunit composition. These findings are consistent with the “channel arrest” hypothesis to reduce turtle brain Na+-K+-ATPase activity during prolonged, but not short-term anoxia, a change that likely helps them overwinter under low temperature, anoxic conditions.

      PubDate: 2017-01-15T19:05:24Z
  • Molecular characterization and functional analysis of a salmon louse
           (Lepeophtheirus salmonis, Krøyer 1838) heme peroxidase with a potential
           role in extracellular matrixes
    • Abstract: Publication date: Available online 11 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Aina-Cathrine Øvergård, Christiane Eichner, Frank Nilsen, Sussie Dalvin
      Heme peroxidases are the most abundant type of peroxidase catalyzing a H2O2-dependent oxidation of a wide variety of substrates. They are involved in numerous processes like the innate immune response, hormone and prostaglandin synthesis and crosslinking of proteins within extracellular matrixes (ECM) as well as molecules within the cuticle and chorion of arthropods and nematodes. In the present study, a Lepeophtheirus salmonis heme peroxidase (LsHPX) 1 was characterized. Amino acids in the active site of heme peroxidases were conserved, and the predicted protein sequence showed the highest similarity to genes annotated as chorion peroxidases and genes suggested to be involved in cuticle hardening or adhesion. LsHPX1 exhibited a dynamic expression during ontogenesis and during the nauplius molting cycle. Transcripts were localized to muscle cells near the muscle-tendon junction, in nerve tissue especially at neuromuscular junctions, subcuticular epithelium, subepithelial cells facing the hemolymph, exocrine glands within the subepithelial tissue and in isolated cells within the testis. Knock-down of LsHPX1 in nauplius larvae decreased the swimming activity of emerging copepodids. Histological analysis of knock-down animals revealed increased spacing between myofibers and changes in subepithelial and exocrine gland tissue. Considering these results, the potential role of LsHPX1 in crosslinking molecules of salmon louse ECMs is discussed.

      PubDate: 2017-01-15T19:05:24Z
  • Different age-dependent performance in Drosophila wild-type Canton-S and
           the white mutant w1118 flies
    • Abstract: Publication date: Available online 10 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Shuang Qiu, Chengfeng Xiao, R Meldrum Robertson
      Aging has significant effects on the locomotor performance of insects including Drosophila. Using a protocol for the high-throughput analysis of fly locomotion in a restricted space, we re-examined age-dependent behavioral characteristics in adult Drosophila. There are multiple important wild-type and background lines including the Canton-S strain and the w1118 strain, which has a null mutation of the white gene. Under standard rearing conditions, we found similar survival curves and median lifespans in Canton-S (50days) and w1118 (54days) strains, however, w1118 flies maintained stable body mass for up to 43days, whereas Canton-S flies gained body mass at young age, followed by a gradual decline. We also tested the behavioral performance of young and old flies. Compared with young w1118 flies (5–10days), old w1118 flies (40–45days) had an increased boundary preference during locomotion in small circular arenas, and increased speed of locomotor recovery from anoxia. Old Canton-S files, however, exhibited unchanged boundary preference and reduced recovery speed from anoxia relative to young flies. In addition, old w1118 flies showed decreased path length per minute and reduced 0.2s path increment compared with young flies, whereas old Canton-S flies displayed the same path length per minute and the same 0.2s path increment compared with young flies. We conclude that age-dependent behavioral and physiological changes differ between Canton-S and w1118 flies. These results illustrate that phenotypic differences between strains can change qualitatively, as well as quantitatively, as the animals age.

      PubDate: 2017-01-15T19:05:24Z
  • Salinity alters snakeskin and mesh transcript abundance and permeability
           in midgut and Malpighian tubules of larval mosquito, Aedes aegypti
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Sima Jonusaite, Andrew Donini, Scott P. Kelly
      This study examined the distribution and localization of the septate junction (SJ) proteins snakeskin (Ssk) and mesh in osmoregulatory organs of larval mosquito (Aedes aegypti), as well as their response to altered environmental salt levels. Ssk and mesh transcripts and immunoreactivity were detected in tissues of endodermal origin such as the midgut and Malpighian tubules of A. aegypti larvae, but not in ectodermally derived hindgut and anal papillae. Immunolocalization of Ssk and mesh in the midgut and Malpighian tubules indicated that both proteins are concentrated at regions of cell-cell contact between epithelial cells. Transcript abundance of ssk and mesh was higher in the midgut and Malpighian tubules of brackish water (BW, 30% SW) reared A. aegypti larvae when compared with freshwater (FW) reared animals. Therefore, [3H]polyethylene glycol (MW 400Da, PEG-400) flux was examined across isolated midgut and Malpighian tubule preparations as a measure of their paracellular permeability. It was found that PEG-400 flux was greater across the midgut of BW versus FW larvae while the Malpighian tubules of BW-reared larvae had reduced PEG-400 permeability in conjunction with increased Cl− secretion compared to FW animals. Taken together, data suggest that Ssk and mesh are found in smooth SJs (sSJs) of larval A. aegypti and that their abundance alters in association with changes in epithelial permeability when larvae reside in water of differing salt content. This latter observation suggests that Ssk and mesh play a role in the homeostatic control of salt and water balance in larval A. aegypti.

      PubDate: 2017-01-07T17:51:35Z
  • Geographic variation and within-individual correlations of physiological
           stress markers in a widespread reptile, the common garter snake
           (Thamnophis sirtalis)
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Eric J. Gangloff, Amanda M. Sparkman, Kaitlyn G. Holden, Caitlyn J. Corwin, Madeline Topf, Anne M. Bronikowski
      Characterizing the baseline and stress-induced hormonal, metabolite, and immune profiles of wild animals is important to assess the impacts of variable environments, including human-induced landscape changes, on organismal health. Additionally, the extent to which these profiles are coordinated across physiological systems within individuals remains an important question in understanding how stressors can differentially affect aspects of an individual's physiology. Here, we present data from wild populations of the common garter snake (Thamnophis sirtalis) on both baseline and stress-induced biomarkers: plasma corticosterone (CORT) concentration, plasma glucose concentration, and whole blood heterophil:lymphocyte ratio. Using a standardized restraint protocol with individuals from populations in disparate portions of this species' range – the Sierra Nevada Mountains of California and the plains of Iowa – we collected blood plasma samples at nine time points over three days. Both CORT and glucose response curves differed between georegions, with Iowa snakes attaining higher glucose concentration and maintaining elevated CORT and glucose levels for a longer duration. Additionally, both the total amount and proportional increases of CORT and glucose were lower in larger and therefore older snakes, suggesting ontogenetic shifts in stress perception or response. Within-individual correlation among the three physiological indicators was significant at the time of capture, absent after 3h in captivity, and partially restored after 3days in captivity, demonstrating the effect of stress on the relationships among these physiological systems. Together, these results provide further evidence for the great physiological flexibility of ectothermic tetrapods in maintaining homeostasis across a range of factors.

      PubDate: 2017-01-07T17:51:35Z
  • Extreme intra-clutch egg size dimorphism is not coupled with corresponding
           differences in antioxidant capacity and stable isotopes between eggs
    • Abstract: Publication date: Available online 4 January 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Maud Poisbleau, Michaël Beaulieu, Nina Dehnhard, Laurent Demongin, Gilles Lepoint, Nicolas Sturaro, Marcel Eens
      Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. In crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. Here, we assessed whether antioxidant and isotopic composition could underlie these differences between eggs within clutches of southern rockhopper penguins (Eudyptes chrysocome chrysocome). The second-laid egg had higher total antioxidant capacity than the first-laid egg, although this was not due to higher antioxidant concentration but to its higher mass. This suggests that resources are allocated by females at a constant rate in both eggs within clutches. Accordingly, we found a strong correlation for isotopic compositions between eggs suggesting that resources were allocated similarly to each egg within the clutch. Overall, we found little evidence for a significant role of antioxidant and isotopic compositions to explain differences in terms of embryo/chick development between eggs in crested penguins. However, since our results suggest a constant rate of antioxidant transfer from females to eggs, limiting the mass of the first-laid egg might represent a strategy for females to spare antioxidant defences and preserve self-maintenance.

      PubDate: 2017-01-07T17:51:35Z
  • Effects of seasonal acclimatization on action potentials and sarcolemmal
           K+ currents in roach (Rutilus rutilus) cardiac myocytes
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Ahmed Badr, Minna Hassinen, Mohamed F. El-Sayed, Matti Vornanen
      Temperature sensitivity of electrical excitability is a potential limiting factor for high temperature tolerance of ectotherms. The present study examines whether heat resistance of electrical excitability of cardiac myocytes is modified by seasonal thermal acclimatization in roach (Rutilus rutilus), a eurythermal teleost species. To this end, temperature dependencies of ventricular action potentials (APs), and atrial and ventricular K+ currents were measured from winter-acclimatized (WiR) and summer-acclimatized (SuR) roach. Under patch-clamp recording conditions, ventricular APs could be triggered over a wide range of temperatures (4–43°C) with prominent changes in resting membrane potential (RMP), AP duration and amplitude. In general, APs of SuR were slightly more tolerant to high temperatures than those of WiR, e.g. the break point temperature (T BP) of RMP was 37.6±0.4°C in WiR and 41±1°C in SuR (p<0.05). Of the two major cardiac K+ currents, the inward rectifier K+ current (IK1) was particularly heat resistant in both SuR (T BP 39.4±0.4°C) and WiR (T BP 40.0±0.4°C) ventricular myocytes. The delayed rectifier K+ current (IKr) was not as heat resistant as IK1. Surprisingly, IKr of WiR tolerated heat better (T BP 31.9±0.8°C) than IKr of SuR (T BP 24.1±0.5°C) (p<0.05). IKr (Erg2) channel transcripts of both atrial and ventricular myocytes were up-regulated in WiR. IK1 (Kir2) channel transcripts were not affected by seasonal acclimatization, although ventricular IK1 current was up-regulated in summer. Collectively, these findings show that thermal tolerance limits of K+ currents in isolated myocytes between seasonally acclimatized roach are much less pronounced than the heat sensitivity of ECG variables in intact fish.

      PubDate: 2016-12-29T14:24:59Z
  • Rates of oxygen uptake increase independently of changes in heart rate in
           late stages of development and at hatching in the green iguana, Iguana
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Marina R. Sartori, Augusto S. Abe, Dane A. Crossley, Edwin W. Taylor
      Oxygen consumption (VO2), heart rate (f H), heart mass (Mh) and body mass (Mb) were measured during embryonic incubation and in hatchlings of green iguana (Iguana iguana). Mean f H and VO2 were unvarying in early stage embryos. VO2 increased exponentially during the later stages of embryonic development, doubling by the end of incubation, while f H was constant, resulting in a 2.7-fold increase in oxygen pulse. Compared to late stage embryos, the mean inactive level of VO2 in hatchlings was 1.7 fold higher, while f H was reduced by half resulting in a further 3.6 fold increase in oxygen pulse. There was an overall negative correlation between mean f H and VO2 when data from hatchlings was included. Thus, predicting metabolic rate as VO2 from measurements of f H is not possible in embryonic reptiles. Convective transport of oxygen to supply metabolism during embryonic incubation was more reliably indicated as an index of cardiac output (COi) derived from the product of f H and Mh. However, a thorough analysis of factors determining rates of oxygen supply during development and eclosion in reptiles will require cannulation of blood vessels that proved impossible in the present study, to determine oxygen carrying capacity by the blood and arteriovenous oxygen content difference (A-V diff), plus patterns of blood flow.

      PubDate: 2016-12-29T14:24:59Z
  • A comparison of blood nitric oxide metabolites and hemoglobin functional
           properties among diving mammals
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Angela Fago, Daniel Garcia Parraga, Elin E. Petersen, Niels Kristensen, Lea Giouri, Frank B. Jensen
      The ability of marine mammals to hunt prey at depth is known to rely on enhanced oxygen stores and on selective distribution of blood flow, but the molecular mechanisms regulating blood flow and oxygen transport remain unresolved. To investigate the molecular mechanisms that may be important in regulating blood flow, we measured concentration of nitrite and S-nitrosothiols (SNO), two metabolites of the vasodilator nitric oxide (NO), in the blood of 5 species of marine mammals differing in their dive duration: bottlenose dolphin, South American sea lion, harbor seal, walrus and beluga whale. We also examined oxygen affinity, sensitivity to 2,3-diphosphoglycerate (DPG) and nitrite reductase activity of the hemoglobin (Hb) to search for possible adaptive variations in these functional properties. We found levels of plasma and red blood cells nitrite similar to those reported for terrestrial mammals, but unusually high concentrations of red blood cell SNO in bottlenose dolphin, walrus and beluga whale, suggesting enhanced SNO-dependent signaling in these species. Purified Hbs showed similar functional properties in terms of oxygen affinity and sensitivity to DPG, indicating that reported large variations in blood oxygen affinity among diving mammals likely derive from phenotypic variations in red blood cell DPG levels. The nitrite reductase activities of the Hbs were overall slightly higher than that of human Hb, with the Hb of beluga whale, capable of longest dives, having the highest activity. Taken together, these results underscore adaptive variations in circulatory NO metabolism in diving mammals but not in the oxygenation properties of the Hb.

      PubDate: 2016-12-29T14:24:59Z
  • Dynamic interactions between corticosterone, corticosteroid binding
           globulin and testosterone in response to capture stress in male breeding
           Eurasian tree sparrows
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Yaqing Li, Yanfeng Sun, Jesse S. Krause, Mo Li, Xuelu Liu, Weiwei Zhu, Yao Yao, Yuefeng Wu, Dongming Li
      In birds, corticosterone (CORT), testosterone (T), and corticosteroid binding globulin (CBG) are involved in modulating the trade-off between reproduction and survival. In response to acute stress, increased total plasma CORT is a ubiquitous phenomenon while T levels can decrease, or remain unchanged. Since CORT and T bind competitively with CBG in birds, the underlying regulatory mechanisms and consequences of their dynamic interactions remain largely unknown. Here, we studied the dynamic changes of total CORT, T, and CBG, and estimated free and bound CORT and T in response to capture stress in male Eurasian tree sparrows (Passer montanus) across the nest building, egg-laying, and nestling stages. We predicted that free, bound and total hormone concentrations would increase for CORT and decrease for T in response to acute stress, and the relative magnitude of these changes would vary with life history stage. We found that baseline and stressed-induced CORT values did not vary across breeding sub-stages. However, total and bound CORT increased with stress while free remained unchanged. Baseline levels of total, free and bound T were highest during the nest building and it was the only stage in which all measures of T were affected by stress. Regardless of breeding stage or restraint stress, we did not detect a significant correlation between CORT and T. CBG was found to be mostly unoccupied by steroid hormones under stress and stress-free conditions and this likely provided an adequate buffer for changes in free levels of CORT and T during unpredictable environmental perturbations.

      PubDate: 2016-12-29T14:24:59Z
  • Transcription of four Rhopalosiphum padi (L.) heat shock protein genes and
           their responses to heat stress and insecticide exposure
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Yuting Li, Qi Zhao, Xinle Duan, Chunman Song, Maohua Chen
      The bird cherry-oat aphid, Rhopalosiphum padi (L.), a worldwide destructive pest, is more heat tolerant than other wheat aphids, and it has developed resistance to different insecticides. Heat shock proteins (HSPs) play an important role in coping with environmental stresses. To investigate Hsp transcriptional responses to heat and insecticide stress, four full-length Hsp genes from R. padi (RpHsp60, RpHsc70, RpHsp70-1, and RpHsp70-2) were cloned. Four RpHsps were expressed during all R. padi developmental stages, but at varying levels. The mRNA levels of RpHsps were increased under thermal stress and reached maximal induction at a lower temperature (36°C) in the alate morph than in the apterous morph (37°C or 38°C). RpHsp expressions under heat stress suggest that RpHsp70-1 and RpHsp70-2 are inducible in both apterous and alate morphs, RpHsc70 is only heat-inducible in apterous morph, and RpHsp60 exhibits poor sensitivity to heat stress. The pretreatment at 37°C significantly increase both the survival rate and the RpHsps expression level of R. padi at subsequent lethal temperature. Under exposure to two sublethal concentrations (LC10 and LC30) of beta-cypermethrin, both RpHsp70-1 and RpHsp70-2 expressions were induced and reached a maximum 24h after exposure. In contrast, expression of RpHsp60 was not induced by either sublethal concentration of beta-cypermethrin. Moreover, the responses of RpHsp70-1 and RpHsp70-2 to heat shock were more sensitive than those to beta-cypermethrin. These results suggest that induction of RpHsp expression is related to thermal tolerance, and that RpHsp70-1 and RpHsp70-2 are the primary genes involved in the response to both heat and pesticide stress.

      PubDate: 2016-12-29T14:24:59Z
  • Nutritional status and functional digestive histology of the carnivorous
           Tasmanian devil (Sarcophilus harrisii)
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Hayley J. Stannard, Lydia Tong, Michelle Shaw, Monique Van Sluys, Bronwyn McAllan, David Raubenheimer
      Tasmanian devils (Sarcophilus harrisii) are the largest carnivorous marsupial in Australia. Currently many animals are being held in captivity as a management procedure to combat Devil Facial Tumor Disease. Only one published study thus far has investigated nutrition in Tasmanian devils, determining their maintenance energy requirements and digestibility on a rodent diet. More information is needed on Tasmanian devil nutritional and gastrointestinal function to aid in their management. Our study aimed to investigate the current nutritional status of Tasmanian devils in a captive population and functional morphology and histology of their gastrointestinal tract. Animals were maintained on a diet of kangaroo, rabbit, quail and chicken wings and digestibility of these items by the devils was high (>85% for dry matter, protein and lipid). Kangaroo and rabbit were high protein diet items while the quail and chicken wings provided high lipid to the diet, and carbohydrates were minimal (≤3% energy). Maintenance energy requirements were determined to be 620kJkg−0.75 d−1 with no significant difference between males and females. Opportunistic samples for gastrointestinal morphology were obtained from captive specimens. Tasmanian devils have a simple digestive tract similar to other dasyurid species. Both the morphology and histology of the gastrointestinal tract show specialization for a high protein carnivorous diet.

      PubDate: 2016-12-22T12:36:08Z
  • Effects of first exogenous nutrients on the mRNA levels of atrogin-1/MAFbx
           and GLUT1 in the skeletal muscles of newly hatched chicks
    • Abstract: Publication date: March 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 205
      Author(s): Daichi Ijiri, Saki Shimamoto, Mana Kawaguchi, Airi Furukawa, Kazuki Nakashima, Osamu Tada, Akira Ohtsuka
      The aim of this study was to examine the effects of first exogenous nutrients on the mRNA levels of muscle atrophy F-box (atrogin-1/MAFbx) and glucose transporters (GLUTs) in the skeletal muscles of newly hatched chicks with no feed experience. In experiment 1, newly hatched chicks had free access to feed or were fasted for the first 24h. The chicks having free access to feed for the first 24h increased their body weight and had decreased atrogin-1/MAFbx mRNA levels in their sartorius and pectoralis major muscles compared with the fasted chicks. In experiment 2, newly hatched chicks received a single feed via intubation into the crop. Three hours after intubation, levels of atrogin-1/MAFbx mRNA in the sartorius muscle were decreased whereas the plasma insulin concentration and phosphorylated AKT levels in the sartorius muscle were increased. In addition, the mRNA levels of GLUT1 and GLUT8 were increased in the sartorius muscle after the intubation. However, in the pectoralis major muscle, AKT phosphorylation and levels of atrogin-1/MAFbx, GLUT1 and GLUT8 mRNA were not affected 3h after intubation. The first exogenous nutrients increased the level of phosphorylated AKT in the sartorius muscle of newly hatched chicks, possibly because of the decrease in atrogin-1/MAFbx mRNA levels. Furthermore, the sartorius muscle in newly hatched chicks appeared to be more susceptible to the first feed compared with the pectoralis major muscle.

      PubDate: 2016-12-22T12:36:08Z
  • Inhibition of eicosanoid signaling leads to increased lipid peroxidation
           in a host/parasitoid system
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Ender Büyükgüzel, Meltem Erdem, Hasan Tunaz, Ceyhun Küçük, Utku Can Atılgan, David Stanley, Kemal Büyükgüzel
      We posed the hypothesis that inhibition of eicosanoid biosynthesis leads to increased lipid peroxidation in insects. Here we report that rearing the greater wax moth, Galleria mellonella, on media supplemented with selected inhibitors of eicosanoid biosynthesis throughout the larval, pupal and adult life led to major alterations in selected oxidative and antioxidative parameters of wax moth and its ectoparasitoid, Bracon hebetor. The highest dietary dexamethasone (Dex), esculetin (Esc) and phenidone (Phe) led to increased malondialdehyde (MDA) levels and to elevated catalase (CAT) and glutathione-S-transferase (GST) activities in all developmental stages of host larvae. Dietary Phe resulted in increased MDA levels, and CAT activity in G. mellonella adults by about 4-fold and about 2-fold, respectively. The Phe effect on GST activity in all stages of the wax moth was expressed in a dose-dependent manner, increased to 140nmol/mg protein/min in larvae. MDA levels were increased by over 30-fold in adult wasps reared on Dex- and Esc-treated hosts. CAT and GST activities were increased in adult parasitoids reared on Esc-and Phe-treated hosts. GST activity of Dex-treated parasitoid larvae increased from about 4 to over 30nmol/mg protein/min. Dietary Phe led to increased GST activity, by about 25-fold, in adult wasps. These data indicate that chronic inhibition of eicosanoid biosynthesis leads to increased oxidative stress, strongly supporting our hypothesis. The significance of this work lies in understanding the roles of eicosanoids in insect biology. Aside from other well-known eicosanoids actions, we propose that eicosanoids mediate reductions in oxidative stress.

      PubDate: 2016-12-08T10:23:23Z
  • Molecular details on gilthead sea bream (Sparus aurata) sensitivity to low
           water temperatures from 1H NMR metabolomics
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Riccardo Melis, Roberta Sanna, Angela Braca, Elia Bonaglini, Roberto Cappuccinelli, Hanno Slawski, Tonina Roggio, Sergio Uzzau, Roberto Anedda
      Biometric and metabolic responses of gilthead sea bream to cold challenge are described following a growth trial divided into three water temperature steps, namely cooling, cold maintenance and recovery. Experimental data provide a useful description of fish response to thermal stress at both zootechnical and molecular level. Although no mortality has been observed, Nuclear Magnetic Resonance-based metabolomics confirms the marked sensitivity of this fish species to low water temperature, and explains some key molecular events associated to fish response to cold. Increase in hepatosomatic index is associated to liver fat accumulation, as a consequence of lipid mobilization from muscle and other extrahepatic tissues, and metabolic rearrangements linked to homeoviscous adaptation of cellular membranes are observed. Following primary responses to descending temperature from 18°C to 11°C, the energetic metabolism (insulin signaling, glycolysis) is first clearly affected; then, at constant low water temperature (11°C), the most perturbed metabolic pathways are related to methionine cycle in liver, while osmoregulatory function is exerted by TMAO in muscle. Water temperature recovery from 11°C to 18°C stimulates gluconeogenesis and glycogen synthesis activities at hepatic level, although the rate of a thermo-compensatory response seems to be slower than that of the cooling phase. The obtained results are intended to guide novel high-performance feed formulations for gilthead sea bream reared during winter.

      PubDate: 2016-12-08T10:23:23Z
  • Metabolic rates are elevated and influenced by maternal identity during
           the early, yolk-dependent, post-hatching period in an estuarine turtle,
           the diamondback terrapin (Malaclemys terrapin)
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Christopher L. Rowe, Ryan J. Woodland, Sarah A. Funck
      Non-genetic maternal effects, operating through a female's physiology or behavior, can influence offspring traits and performance. Here we examined potential maternal influences on metabolic rates (MR) of offspring in an estuarine turtle, the diamondback terrapin (Malaclemys terrapin). Females and their eggs were collected from the field and the eggs incubated in the laboratory for subsequent measurement of MR of females, late-stage embryos, newly-hatched individuals that were nutritionally dependent on yolk, and older hatchlings that had depleted their yolk reserves and thus were independent of energetic contributions from the female. Female identity significantly affected MR of yolk-dependent hatchlings but, after yolk was depleted, MR of offspring converged and no longer reflected the maternal influence. Offspring from different females also differed in size, which influenced offspring MR and growth, but there was no correlation between female MR or size and offspring traits. MR of the older, yolk-independent hatchlings was lower overall than yolk-dependent hatchlings but correlated positively with growth rates and prior developmental rate (e.g. negatively correlated with time to hatching). Unlike another turtle species (snapping turtles), in which maternally-related differences in offspring MR were retained after yolk depletion, the maternal influence on offspring MR in diamondback terrapins is limited to early hatchling development and growth. The transient nature of the maternal effect, which was present only during the period that hatchlings were metabolizing yolk, suggests that variation among females in the composition of yolk deposited in eggs could be responsible for the differences observed in this study.

      PubDate: 2016-12-08T10:23:23Z
  • Kisspeptin system in pejerrey fish (Odontesthes bonariensis).
           Characterization and gene expression pattern during early developmental
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): M. Oswaldo Tovar Bohórquez, Alejandro S. Mechaly, Lily C. Hughes, Daniela Campanella, Guillermo Ortí, Luis F. Canosa, Gustavo M. Somoza
      In vertebrates, kisspeptins and their receptors are known to be related to puberty onset and gonadal maturation, however, there are few studies concerning their role in early development. Here, we characterize the kisspeptin system in the pejerrey, Odontesthes bonariensis, a fish with strong temperature-dependent sex determination. We reconstructed the phylogenetic history of the two ligands (kiss1 and kiss 2) and two receptors (kissr2 and kissr3) in pejerrey in the context of recent classifications of bony fishes, determined their tissue distribution and documented the early expression pattern of these ligands and receptors. Phylogenetic analysis of these gene families clearly resolved the percomorph clade and grouped pejerrey with Beloniformes. Paralogous sets of genes putatively arising from the teleost-specific genome duplication event (3R) were not detected. Kisspeptins and their receptors showed a wide tissue distribution in adult pejerrey, including tissues not related to reproduction. In larvae reared at 24°C, the four kisspeptin elements were expressed in the head from week 1 to week 8 of life, with no differences in transcript levels. Larvae kept at a female-producing temperature (17°C) did not show statistically significant differences in the transcript levels of all analyzed genes during the sex determination/differentiation period; however, in those larvae raised at male producing temperature (29°C), kiss2 levels were increased at week 4 after hatching. These results showed that all members of the kisspeptin system are expressed at this early period, and the increase of kiss2 transcripts at week 4 could be interpreted as it would be related to the differentiation of the brain-pituitary axis in male development.

      PubDate: 2016-12-08T10:23:23Z
  • Trans- and paracellular calcium transport along the small and large
           intestine in horses
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): M.R. Wilkens, L. Marholt, N. Eigendorf, A.S. Muscher-Banse, K. Feige, B. Schröder, G. Breves, A. Cehak
      Intestinal calcium absorption plays a key role in the maintenance of calcium homeostasis and may either occur by paracellular or transcellular mechanisms. The horse has some unique peculiarities in calcium homeostasis compared to other species including a high absorptive capacity for calcium in the intestine, high plasma calcium concentrations, high renal excretion, and low plasma concentrations of vitamin D metabolites. So far, knowledge about the underlying mechanisms and the regulation of intestinal calcium absorption is still limited concerning this species. Several studies have documented that intestinal calcium transport in horses is not as dependent on vitamin D as in other species. However, published data on other potential regulatory mechanisms are still lacking. In the present study, paracellular and transcellular transport mechanisms for intestinal calcium transport along the intestinal axis were identified in horses using the Ussing chamber technique. Furthermore, the expression of respective transport proteins including transient receptor potential vanilloid member 6, calbindin-D9k and calcium ATPase type 1 in line with the determined calcium flux rates was documented. In respect to regulation of transepithelial calcium transport, novel regulatory proteins for maintaining calcium homeostasis such as B-box and SPRY-domain containing protein and calmodulin were investigated for the first time in equine intestinal tissues in this study. This provides the basis for a new approach for a better understanding of equine calcium homeostasis regulation.

      PubDate: 2016-12-08T10:23:23Z
  • Effect of environmental salinity manipulation on uptake rates and
           distribution patterns of waterborne amino acids in the Pacific hagfish
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Chris N. Glover, Tamzin A. Blewett, Chris M. Wood
      Among vertebrates, hagfish are the only known iono- and osmoconformers, and the only species thus far documented to absorb amino acids directly across the skin. In the current study, short-term (6h) manipulations of exposure salinities (75–125% seawater) were conducted to determine whether changes in osmotic demands influenced the uptake and tissue distribution of waterborne amino acids (alanine, glycine and phenylalanine), in the Pacific hagfish, Eptatretus stoutii. No changes in erythrocyte or muscle amino acid accumulation rates were noted, but the patterns of plasma amino acid accumulation were suggestive of regulation. Contrary to expectations, glycine transport across the skin in vitro was enhanced in the lowest exposure salinity, but no other salinity-dependent changes were demonstrated. Overall, this study indicates that uptake and distribution of amino acids varies with salinity, but not in a manner that is consistent with a role for the studied amino acids in maintaining osmotic balance in hagfish.

      PubDate: 2016-12-08T10:23:23Z
  • Earth-strength magnetic field affects the rheotactic threshold of
           zebrafish swimming in shoals
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Alessandro Cresci, Rosario De Rosa, Nathan F. Putman, Claudio Agnisola
      Rheotaxis, the unconditioned orienting response to water currents, is a main component of fish behavior. Rheotaxis is achieved using multiple sensory systems, including visual and tactile cues. Rheotactic orientation in open or low-visibility waters might also benefit from the stable frame of reference provided by the geomagnetic field, but this possibility has not been explored before. Zebrafish (Danio rerio) form shoals living in freshwater systems with low visibility, show a robust positive rheotaxis, and respond to geomagnetic fields. Here, we investigated whether a static magnetic field in the Earth-strength range influenced the rheotactic threshold of zebrafish in a swimming tunnel. The direction of the horizontal component of the magnetic field relative to water flow influenced the rheotactic threshold of fish as part of a shoal, but not of fish tested alone. Results obtained after disabling the lateral line of shoaling individuals with Co2+ suggest that this organ system is involved in the observed magneto-rheotactic response. These findings constitute preliminary evidence that magnetic fields influence rheotaxis and suggest new avenues for further research.

      PubDate: 2016-12-08T10:23:23Z
  • Intestinal response to salinity challenge in the Senegalese sole (Solea
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): I. Ruiz-Jarabo, A. Barany, I. Jerez-Cepa, J.M. Mancera, J. Fuentes
      Fish are continuously forced to actively absorb or expel water and ions through epithelia. Most studies have focused on the gill due to its role in Na+ and Cl− trafficking. However, comparatively few studies have focused on the changing function of the intestine in response to external salinity. Therefore, the present study investigated the main intestinal changes of long-term acclimation of the Senegalese sole (Solea senegalensis) to 5, 15, 38 and 55ppt. Through the measurement of short-circuit current (Isc) in Ussing chambers and biochemical approaches, we described a clear anterior/posterior functional regionalization of the intestine in response to salinity. The use of specific inhibitors in Ussing chamber experiments, revealed that the bumetanide-sensitive Na+/K+/Cl− co-transporters are the main effectors of Cl− uptake in both anterior intestine and rectum. Additionally, the use of the anion exchanger specific inhibitor, DIDS, showed a salinity/region dependency of anion exchanger function. Moreover, we also described ouabain-sensitive Na+/K+-ATPase (NKA) and Bafilomycin A1-sensitive H+-ATPase activities (HA), which displayed changes related to salinity and intestinal region. However, the most striking result of the present study is the description of an omeprazole-sensitive H+/K+-ATPase (HKA) in the rectum of Senegalese sole. Its activity was consistently measurable and increased at lower salinities, reaching rates even higher than those of the NKA. Together our results provide new insights into the changing role of the intestine in response to external salinity in teleost fish. The rectal activity of HKA offers an alternative/cooperative mechanism with the HA in the final processing of intestinal water absorption by apical titration of secreted bicarbonate.

      PubDate: 2016-11-30T09:28:34Z
  • Acute exposure to high environmental ammonia (HEA) triggers the emersion
           response in the green shore crab
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Alex M. Zimmer, Chris M Wood
      The physiological effects of high environmental ammonia (HEA) exposure have been well documented in many aquatic species. In particular, it has recently been demonstrated that exposure to ammonia in fish leads to a similar hyperventilatory response as observed during exposure to hypoxia. In littoral crabs, such as the green crab (Carcinus maenas), exposure to severe hypoxia triggers an emersion response whereby crabs escape hypoxia to breathe air. We hypothesized that exposure to HEA in green crabs would lead to a similar behavioural response which is specific to ammonia. Using an experimental arena containing a rock bed onto which crabs could emerse, we established that exposure to HEA (4mmol/l NH4HCO3) for 15min triggers emersion in crabs. In experiments utilizing NaHCO3 controls and NH4HCO3 injections, we further determined that emersion was triggered specifically by external ammonia and was independent of secondary acid-base or respiratory disturbances caused by HEA. We then hypothesized that emersion from HEA provides a physiological benefit, similar to emersion from hypoxia. Exposure to 15min of HEA without emersion (no rock bed present) caused significant increases in arterial haemolymph total ammonia (Tamm), pH, and [HCO3 −]. When emersion was allowed, arterial haemolymph Tamm and [HCO3 −] increased, but no alkalosis developed. Moreover, emersion decreased haemolymph partial pressure of NH3 relative to crabs which could not emerse. Overall, we demonstrate a novel behavioural response to HEA exposure in crabs which we propose may share similar mechanistic pathways with the emersion response triggered by hypoxia.

      PubDate: 2016-11-30T09:28:34Z
  • Forkhead box O1 in grass carp Ctenopharyngodon idella: Molecular
           characterization, gene structure, tissue distribution and mRNA expression
           in insulin-inhibited adipocyte lipolysis
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Jian Sun, Pei-zhen Xiao, Zhi-guang Chang, Hong Ji, Zhen-Yu Du, Li-Qiao Chen
      Factor forkhead box O1 (FoxO1) is a transcription factor and plays an important role in insulin-mediated lipid metabolism. In the present study, two distinct FoxO1 cDNAs, designated FoxO1a and FoxO1b, were firstly isolated and characterized from grass carp Ctenopharyngodon idella, encoding peptides of 654 and 631 amino acids, respectively. Phylogenetic and synteny analyses suggested that FoxO1a and FoxO1b were derived from paralogous genes that could be originated from teleost-specific genome duplication (TSGD) event. Analysis of the exon–intron structures clarified that grass carp FoxO1a and FoxO1b comprise 3 coding exons and contain a extra intron compared with human and mouse FoxO1. Both FoxO1a and FoxO1b mRNAs were expressed in a wide range of tissues, but the abundance of each FoxO1 mRNA showed the tissue- dependent expression patterns. Time-course analysis of FoxO1 expressions indicated that the level of FoxO1a mRNA reached almost maximal level at day 2, while that of FoxO1b mRNA reached almost maximal level at day 4 during grass carp primary preadipocyte differentiation. In insulin-inhibited adipocyte lipolysis, only FoxO1a showed a significant decrease in adipocyte, indicating that two FoxO1 isoforms may serve somewhat different roles in the regulation of lipolysis by insulin. These results suggested that grass carp FoxO1a and FoxO1b may play different roles in tissues, and their expression levels were differently modulated by insulin in adipocyte.

      PubDate: 2016-11-30T09:28:34Z
  • Ghrelin in Senegalese sole (Solea senegalensis) post-larvae: Paracrine
           effects on food intake
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Carmen Navarro-Guillén, Manuel Yúfera, Sofia Engrola
      Successful food consumption and digestion depend on specifics anatomical and behavioral characteristics and corresponding physiological functions that should be ready to work at the appropriate time. The physiological regulation of appetite and ingestion involves a complex integration of peripheral and central signals by the brain. Ghrelin is a peptide hormone involved in the control of energy homeostasis and increases food intake in mammals, however ghrelin has species-specific actions on food intake in fish. The aim of this study was to investigate whether this peptide has an orexigenic or anorexigenic role in Senegalese sole (Solea senegalensis) in order to improve the knowledge of the physiological basis underlying feeding activity. Feed intake was measured at several sampling points to determine the overall action time of the peptide and its effect in Senegalese sole food intake. Artemia protein digestibility and retention were determined in order to analyze the ghrelin effect in fed and fasted Senegalese sole post-larvae. Results suggested that ghrelin acts as orexigenic hormone in Senegalese sole, with a response time around 25min. Results indicated that Senegalese sole post-larvae are able to maintain absorption and retention capacities independently of feeding rate and nutritional status. Furthermore, the present study gives insight for the first time of the fate of the retained amino acids, being mainly used for protein accretion (86.79% of retained amino acids recovered in protein and FAA fractions).

      PubDate: 2016-11-30T09:28:34Z
  • Milk composition of free-ranging red hartebeest, giraffe, Southern
           reedbuck and warthog and a phylogenetic comparison of the milk of African
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): G. Osthoff, A. Hugo, M. Madende, F. Deacon, P.J. Nel
      The composition of major nutrients and fatty acids of the milk of three species, red hartebeest, Southern reedbuck and warthog, and milk fatty acids of giraffe, that have not been published before, are reported, and together with the same parameters of 11 species previously published, were incorporated in a phylogenetic comparison. Unique properties of milk composition have been observed. Southern reedbuck milk seems to have a complex casein composition, similar to that of sheep. Milk composition varies between species. Although some differences may be ascribed to biological condition, such as stage of lactation, or ecological factors, such as availability of certain nutrients, the contribution by evolutionary history is not well documented and the emphasis is usually on the composition of the macro nutrients. Phylogenetic comparisons often lack representatives of multiple species of taxonomic groups and sub-groups. To date phylogenetic comparisons of milk composition have been carried out by using data from different publications. The problem with this approach is that the ecological factors cannot be completely ruled out. A statistical phylogenetic comparison by PCA between 15 species representing 7 different suborders, families or subfamilies of African Artiodactyla was carried out. The phylogenetic properties showed that the milk composition of the Bovinae, represented here by the subfamilies Bovini and Tragelaphini, differs from the other taxonomic groups, in that the Alcelaphinae had a high milk fat content of the medium chain length fatty acids C8–C12 (>17% of total fatty acids) and the Hippotraginae high amounts of oligosaccharides (>0.4%).

      PubDate: 2016-11-30T09:28:34Z
  • Comparing biomarker responses during thermal acclimation: A lethal vs
           non-lethal approach in a tropical reef clownfish
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Carolina Madeira, Diana Madeira, Mário S. Diniz, Henrique N. Cabral, Catarina Vinagre
      Knowledge of thermal stress biology for most tropical fish species in reef ecosystems under climate change is still quite limited. Thus, the objective of this study was to measure the time-course changes of thermal stress biomarkers in the commercially exploited coral reef fish Amphiprion ocellaris, during a laboratory simulated event of increased temperature. Heat shock protein 70kDa (Hsp70) and total ubiquitin (Ub) were determined in the muscle (lethal method) and in the fin (non-lethal alternative method) under two temperature treatments (control – 26°C and elevated temperature – 30°C) throughout one month with weekly samplings. Results suggest that biomarker basal levels are tissue-specific and influence the degree of response under temperature exposure. Responses were highly inducible in the muscle but not in fin tissue, indicating that the latter is not reliable for monitoring purposes. Thermal stress was observed in the muscle after one week of exposure (both biomarkers increased significantly) and Ub levels then decreased, suggesting the animals were able to acclimate by maintaining high levels of Hsp70 and through an effective protein turnover. In addition, the results show that mortality rates did not differ between treatments. This indicates that A. ocellaris is capable of displaying a plastic response to elevated temperature by adjusting the protein quality control system to protect cell functions, without decreasing survival. Thus, this coral reef fish species presents a significant acclimation potential under ocean warming scenarios of +4°C. Monitoring of thermal stress through a non-lethal method, fin-clipping, although desirable proved to be inadequate for this species.

      PubDate: 2016-11-30T09:28:34Z
  • Modulation of the heat shock response is associated with acclimation to
           novel temperatures but not adaptation to climatic variation in the ants
           Aphaenogaster picea and A. rudis
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Sara Helms Cahan, Andrew D. Nguyen, John Stanton-Geddes, Clint A. Penick, Yainna Hernáiz-Hernández, Bernice B. DeMarco, Nicholas J. Gotelli
      Ecological diversification into thermally divergent habitats can push species toward their physiological limits, requiring them to accommodate temperature extremes through plastic or evolutionary changes that increase persistence under the local thermal regime. One way to withstand thermal stress is to increase production of heat shock proteins, either by maintaining higher baseline abundance within cells or by increasing the magnitude of induction in response to heat stress. We evaluated whether environmental variation was associated with expression of three heat shock protein genes in two closely-related species of woodland ant, Aphaenogaster picea and A. rudis. We compared adult workers from colonies collected from 25 sites across their geographic ranges. Colonies were maintained at two different laboratory temperatures, and tested for the independent effects of environment, phylogeny, and acclimation temperature on baseline and heat-induced gene expression. The annual maximum temperature at each collection site (Tmax) was not a significant predictor of either baseline expression or magnitude of induction of any of the heat shock protein genes tested. A phylogenetic effect was detected only for basal expression of Hsp40, which was lower in the most southern populations of A. rudis and higher in a mid-range population of possible hybrid ancestry. In contrast, a higher acclimation temperature significantly increased baseline expression of Hsc70-4, and increased induction of Hsp40 and Hsp83. Thus, physiological acclimation to temperature variation appears to involve modulation of the heat shock response, whereas other mechanisms are likely to be responsible for evolutionary shifts in thermal performance associated with large-scale climate gradients.

      PubDate: 2016-11-30T09:28:34Z
  • Antioxidant responses in hibernating Chinese soft-shelled turtle
           Pelodiscus sinensis hatchlings
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Wen-yi Zhang, Cui-juan Niu, Bo-jian Chen, Lin Yuan
      The antioxidant defense system protects turtles from oxidative stress during hibernation. The present study examined changes of the antioxidant enzymes both on mRNA level and enzyme activity level during hibernation of Chinese soft-shelled turtle Pelodiscus sinensis hatchlings. The upstream regulator NF-E2 related factor 2 (Nrf2) mRNA was also measured. Samples were taken at pre-hibernation (17.0°C, Mud temperature (MT)), hibernation (5.8°C, MT) and arousal (20.1°C, MT). Nrf2 exhibited a tissue-specific pattern of expression with a decrease in the brain, slight increase in the liver and heart during hibernation, and significant increase during arousal in all the three tissues. Superoxide dismutase (SOD) mRNA, catalase (CAT) mRNA, and glutathione peroxidase 3 (GPx3) mRNA exhibited a similar pattern as Nrf2 in the brain and liver during the entire hibernation period. Hepatic GPx4 mRNA level increased during hibernation and decreased during arousal, whereas it did not change in the heart. Cerebral SOD and CAT activities kept stable during the experimental period, but GPx activity decreased significantly during hibernation and arousal. Hepatic GPx enzyme activity did not change, whereas those of SOD and CAT exhibited a notable decrease during arousal. Malondialdehyde concentration did not increase during the hibernation process, indicating an effective protection of the antioxidant defense system.

      PubDate: 2016-11-23T05:31:06Z
  • Biological and environmental influence on tissue fatty acid compositions
           in wild tropical tunas
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Fany Sardenne, Edouard Kraffe, Aurélien Amiel, Edwin Fouché, Laurent Debrauwer, Frédéric Ménard, Nathalie Bodin
      This study examined the fatty acid composition of three sympatric tropical tuna species (bigeye Thunnus obesus, yellowfin T. albacares and skipjack tuna Kastuwonus pelamis) sampled in the Western Indian Ocean in 2013. The fatty acid compositions of neutral and polar lipids, respectively involved in energy storage and cell membrane structure, were explored and compared in four tissues (red and white muscles, liver and gonads), according to biological (size, sex and maturity) and environmental (season and area) factors. The liver and the red muscle were the fattest tissues (i.e., higher levels of storage lipids) in all species and polar lipids were the lowest in the white muscle. Species and tissue types explained most differences in fatty acid compositions, while environmental factors had limited effects, except in the hepatic cell membrane where fatty acid composition varied with monsoons. Docosahexaenoic acid (22:6n-3) was the major fatty acid in both polar and neutral lipid fractions, especially in muscles. Eicosapentaenoic acid (20:5n-3) and oleic acid (18:1n-9) were in higher proportion in neutral than in polar lipids. Arachidonic acid (20:4n-6) and 22:6n-3, together with docosapentaenoic acid (22:5n-6) and stearic acid (18:0), showed preferential accumulation in polar lipids. 20:4n-6 was particularly involved in cell membranes of ovary and white muscle. Overall, an important inter-individual variability in fatty acid compositions of structural lipids was found within tissue types despite considering biological factors that are most likely to influence this type of lipids. It suggests that fatty acid profiles are influenced by individual-specific behaviors.

      PubDate: 2016-11-23T05:31:06Z
  • Dietary alpha-ketoglutarate promotes higher protein and lower
           triacylglyceride levels and induces oxidative stress in larvae and young
           adults but not in middle-aged Drosophila melanogaster
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Maria M. Bayliak, Maria P. Lylyk, Halyna V. Shmihel, Oksana M. Sorochynska, Olesia I. Semchyshyn, Janet M. Storey, Kenneth B. Storey, Volodymyr I. Lushchak
      Alpha-ketoglutarate (AKG) is involved in multiple metabolic and regulatory pathways. In this work, the effects of AKG-supplemented diets on selected physiological responses and metabolic processes, including metabolism of reactive oxygen species, was assessed in larvae and adult (both 2 and 24days old) Drosophila melanogaster. Dietary supplementation with AKG resulted in dose-dependent effects on larval development, body composition and antioxidant status of third instar larvae. Larvae and young (2days post-eclosion) adult females fed on AKG shared similar metabolic changes such as higher total protein levels, lower triacylglyceride levels and higher values for oxidative stress indices, namely lipid peroxides and low molecular mass thiols. The latter indicated the development of oxidative stress which, in turn, may induce adaptive responses that can explain the higher resistance of AKG-fed young females to heat shock and hydrogen peroxide exposure. In contrast to young flies, middle-aged females (24days) on AKG-containing diet possessed higher total protein, glucose and triacylglyceride levels, whereas oxidative stress parameters were virtually the same as compared with control females of the same age. In parallel, females fed an AKG-supplemented diet showed lower fecundity, higher heat shock resistance but no change in oxidative stress resistance at middle age which in combination with levels of protein, glucose, and triacylglycerides can be considered as potentially beneficial AKG effects for aging organisms. To our best knowledge, this is the first study on age-matched AKG influence on animals' organism which shows that Drosophila may be used as a model for previous quick study in cost-efficient manner age-related AKG effects in mammals and humans.

      PubDate: 2016-11-23T05:31:06Z
  • Synchronization to light and mealtime of daily rhythms of locomotor
           activity, plasma glucose and digestive enzymes in the Nile tilapia
           (Oreochromis niloticus)
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Bartira Guerra-Santos, José Fernando López-Olmeda, Bruno Olivetti de Mattos, Alice Borba Baião, Denise Soledade Peixoto Pereira, Francisco Javier Sánchez-Vázquez, Robson Bahia Cerqueira, Ricardo Castelo Branco Albinati, Rodrigo Fortes-Silva
      The light–dark cycle and feeding can be the most important factors acting as synchronizers of biological rhythms. In this research we aimed to evaluate synchronization to feeding schedule of daily rhythms of locomotor activity and digestive enzymes of tilapia. For that purpose, 120 tilapias (65.0±0.6g) were distributed in 12 tanks (10 fish per tank) and divided into two groups. One group was fed once a day at 11:00h (zeitgeber time, ZT6) (ML group) and the other group was fed at 23:00h (ZT18) (MD group). The fish were anesthetized to collect samples of blood, stomach and midgut at 4-hour intervals over a period of 24h. Fish fed at ML showed a diurnal locomotor activity (74% of the total daily activity occurring during the light phase) and synchronization to the feeding schedule, as this group showed anticipation to the feeding time. Fish fed at MD showed a disruption in the pattern of locomotor activity and became less diurnal (59%). Alkaline protease activity in the midgut showed daily rhythm with the achrophase at the beginning of the dark phase in both ML and MD groups. Acid protease and amylase did not show significant daily rhythms. Plasma glucose showed a daily rhythm with the achrophase shifted by 12h in the ML and MD groups. These results revealed that the feeding time and light cycle synchronize differently the daily rhythms of behavior, digestive physiology and plasma metabolites in the Nile tilapia, which indicate the plasticity of the circadian system and its synchronizers.

      PubDate: 2016-11-23T05:31:06Z
  • l-Leucine acts as a potential agent in reducing body temperature at
           hatching and affords thermotolerance in broiler chicks
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Guofeng Han, Hui Yang, Mohammad A. Bahry, Phuong V. Tran, Phong H. Do, Hiromi Ikeda, Mitsuhiro Furuse, Vishwajit S. Chowdhury
      Thermal manipulation (TM) of incubation temperature causes metabolic alterations and contributes to improving thermotolerance in chicks post hatching. However, there has been no report on amino acid metabolism during TM and the part it plays in thermotolerance. In this study, we therefore first analyzed free amino acid concentrations in the embryonic brain and liver during TM (38.6°C, 6h/d during embryonic day (ED) 10 to ED 18). It was found that leucine (Leu), phenylalanine and lysine were significantly decreased in the embryonic brain and liver. We then chose l-Leu and other branched-chain amino acids (l-isoleucine (L-Ile) and l-valine (l-Val)) for in ovo injection on ED 7 to reveal their roles in thermoregulation, growth, food intake and thermotolerance in chicks. It was found that in ovo injection of l-Leu, but not of l-Ileu or l-Val, caused a significant decline in body temperature at hatching and increased food intake and body weight gain in broiler chicks. Interestingly, in ovo injection of l-Leu resulted in the acquisition of thermotolerance under high ambient temperature (35±1°C for 180min) in comparison with the control thermoneutral temperature (28±1°C for 180min). These results indicate that the free amino acid concentrations during embryogenesis were altered by TM. l-Leu administration in eggs caused a reduction in body temperature at hatching, and afforded thermotolerance in heat-exposed young chicks, further suggesting that l-Leu may be one of the key metabolic factors involved in controlling body temperature in embryos, as well as in producing thermotolerance after hatching.

      PubDate: 2016-11-23T05:31:06Z
  • Cortisol regulates nitric oxide synthase in freshwater and seawater
           acclimated rainbow trout, Oncorhynchus mykiss
    • Abstract: Publication date: February 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 204
      Author(s): Lucie Gerber, Steffen S. Madsen, Frank B. Jensen
      Cortisol and nitric oxide (NO) are regulators of ion transport and metabolic functions in fish. In the gill, they show opposite effects on Na+/K+-ATPase (NKA) activity: cortisol stimulates NKA activity while NO inhibits NKA activity. We hypothesized that cortisol may impact NO production in osmoregulatory tissues by regulating NO synthase (NOS) expression. We evaluated the influence of cortisol treatment on mRNA expression of Nos1 and Nos2 in gill, kidney and middle intestine of both freshwater (FW) and seawater (SW) acclimated rainbow trout and found both tissue- and salinity-dependent effects. Nos2 expression was down-regulated in the gill by cortisol injection in both FW and SW trout. This was substantiated by incubating gill tissue with cortisol ex vivo. Similarly, cortisol injection significantly down-regulated Nos2 expression in kidney of SW fish but not in FW fish. In the middle intestine, Nos2 expression was up-regulated by cortisol injection in FW but unchanged in SW fish. Nos1 expression was up-regulated by cortisol injection in FW kidney and down-regulated in SW kidney, whereas it was unaffected in gill and middle intestine of FW and SW fish. Our data provide the first evidence that cortisol may influence NO production in fish by regulating Nos expression. Indeed, the down-regulation of Nos2 expression by cortisol in the gill may prevent the inhibitory effect of NO on NKA activity thereby furthering the stimulatory effect of cortisol on ion-transport.

      PubDate: 2016-11-17T03:37:58Z
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