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  Subjects -> BIOLOGY (Total: 3086 journals)
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BIOCHEMISTRY (243 journals)                  1 2 | Last

Showing 1 - 200 of 243 Journals sorted alphabetically
AAPS PharmSciTech     Hybrid Journal   (Followers: 7)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Central Science     Open Access   (Followers: 9)
ACS Chemical Biology     Full-text available via subscription   (Followers: 281)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 20)
Acta Biochimica Polonica     Open Access  
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 10)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 9)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 10)
Advances in Biological Chemistry     Open Access   (Followers: 8)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 7)
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: 18)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 3)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
American Journal of Biochemistry     Open Access   (Followers: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 62)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Polymer Science     Open Access   (Followers: 30)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical and Bioanalytical Chemistry Research     Open Access   (Followers: 1)
Analytical Biochemistry     Hybrid Journal   (Followers: 165)
Angiogenesis     Hybrid Journal   (Followers: 3)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 54)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 12)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 42)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 16)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 8)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 20)
Archives of Insect Biochemistry and Physiology     Hybrid Journal  
Archives Of Physiology And Biochemistry     Hybrid Journal  
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 3)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 24)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 5)
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: 24)
Biochemical Pharmacology     Hybrid Journal   (Followers: 10)
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: 332)
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     Hybrid Journal   (Followers: 15)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 6)
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: 7)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 14)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 10)
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: 7)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofarmasi Journal of Natural Product Biochemistry     Open Access  
Biofuels     Hybrid Journal   (Followers: 11)
Biogeochemistry     Hybrid Journal   (Followers: 15)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 22)
Biomaterials Research     Open Access   (Followers: 4)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 21)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
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  
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 7)
Cell Chemical Biology     Hybrid Journal   (Followers: 1)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
ChemBioChem     Hybrid Journal   (Followers: 8)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 20)
Chemical Engineering Journal     Hybrid Journal   (Followers: 52)
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: 7)
Chemistry & Biology     Full-text available via subscription   (Followers: 32)
Chemistry and Ecology     Hybrid Journal  
ChemTexts     Hybrid Journal  
Clinica Chimica Acta     Hybrid Journal   (Followers: 33)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 18)
Clinical Chemistry     Full-text available via subscription   (Followers: 69)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 62)
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: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 6)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)
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 Biochemical Engineering     Hybrid Journal  
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Medicinal Chemistry     Hybrid Journal   (Followers: 15)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 31)
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: 58)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Food & Function     Full-text available via subscription   (Followers: 7)
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: 18)
Green Chemistry     Full-text available via subscription   (Followers: 10)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 7)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 2)
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: 6)
International Journal of Biochemistry and Biophysics     Open Access   (Followers: 1)
International Journal of Biological Chemistry     Open Access   (Followers: 2)
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: 4)
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: 3)
Journal of Biochemical and Biophysical Methods     Hybrid Journal   (Followers: 4)
Journal of Biochemistry     Hybrid Journal   (Followers: 41)
Journal of Biochemistry and Molecular Biology Research     Open Access  
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 199)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 6)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 4)
Journal of Chemical Biology     Hybrid Journal   (Followers: 3)
Journal of Chemical Neuroanatomy     Hybrid Journal  
Journal of Clinical Lipidology     Hybrid Journal   (Followers: 2)
Journal of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology     Hybrid Journal   (Followers: 5)
Journal of Drug Discovery and Therapeutics     Open Access  
Journal of Enzyme Inhibition and Medicinal Chemistry     Open Access   (Followers: 3)
Journal of Evolutionary Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 6)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 6)
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: 4)
Journal of Molecular Diagnostics     Hybrid Journal   (Followers: 5)
Journal of Neurochemistry     Hybrid Journal   (Followers: 4)
Journal of Nutritional Biochemistry     Hybrid Journal   (Followers: 7)
Journal of Pediatric Biochemistry     Hybrid Journal   (Followers: 1)
Journal of Peptide Science     Hybrid Journal   (Followers: 21)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 2)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 6)
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 10)
La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine     Hybrid Journal  
Lab on a Chip     Full-text available via subscription   (Followers: 37)
Laboratory Techniques in Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 4)
Marine Chemistry     Hybrid Journal   (Followers: 7)
Methods in Enzymology     Full-text available via subscription   (Followers: 12)
Molecular and Biochemical Parasitology     Hybrid Journal   (Followers: 2)
Molecular and Cellular Biochemistry     Hybrid Journal   (Followers: 4)
Molecular Aspects of Medicine     Hybrid Journal   (Followers: 3)
Molecular Informatics     Hybrid Journal   (Followers: 5)
Molecular inhibitors in targeted therapy     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
Mycologia     Hybrid Journal  
Mycology : An International Journal on Fungal Biology     Hybrid Journal   (Followers: 5)
Natural Products and Bioprospecting     Open Access   (Followers: 2)
Nature Chemical Biology     Full-text available via subscription   (Followers: 74)
Nature Communications     Open Access   (Followers: 208)
Neurosignals     Open Access  
New Comprehensive Biochemistry     Full-text available via subscription  

        1 2 | Last

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  [3175 journals]
  • Expression profile of glucose transport-related genes under chronic and
           acute exposure to growth hormone in zebrafish
    • Authors: Camila Dalmolin; Daniela Volcan Almeida; Marcio Azevedo Figueiredo; Luis Fernando Marins
      Pages: 1 - 6
      Abstract: Publication date: July 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 221
      Author(s): Camila Dalmolin, Daniela Volcan Almeida, Marcio Azevedo Figueiredo, Luis Fernando Marins
      The brain is a highly demanding organ in terms of energy requirements, and precise regulatory mechanisms must operate to ensure adequate energy delivery to maintain normal neuronal activity. Of the energy-promoting substrates present in the circulation, glucose is preferred by the brain, and as with all other substrates, its utilization depends on the presence of humoral factors such as hormones including growth hormone (GH). Glucose enters the cells though specific transport proteins. Among all transporter families and subtypes described to date, the most studied ones are the glucose transporters (GLUTs). The aim of this study is to determine a possible relationship between GH and GLUTs. Therefore, we evaluated the effect of GH-transgenesis and recombinant GH injections upon GLUT expression in the brain of male zebrafish. Overall, the results demonstrated that increasing the GH concentrations above the normal level, via transgenesis or injection, in the fish may impair energy uptake by the brain. This appeared to occur through downregulation of most of the analyzed GLUTs.

      PubDate: 2018-03-19T06:59:32Z
      DOI: 10.1016/j.cbpa.2018.02.015
      Issue No: Vol. 221 (2018)
       
  • Mitochondrial phenotype during torpor: Modulation of mitochondrial
           
    • Authors: Pablo A. Cortes; Francisco Bozinovic; Pierre U. Blier
      Pages: 7 - 14
      Abstract: Publication date: July 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 221
      Author(s): Pablo A. Cortes, Francisco Bozinovic, Pierre U. Blier
      Mammalian torpor is a phenotype characterized by a controlled decline of metabolic rate, generally followed by a reduction in body temperature. During arousal from torpor, both metabolic rate and body temperature rapidly returns to resting levels. Metabolic rate reduction experienced by torpid animals is triggered by active suppression of mitochondrial respiration, which is rapidly reversed during rewarming process. In this study, we analyzed the changes in the maximal activity of key enzymes related to electron transport system (complexes I, III and IV) in six tissues of torpid, arousing and euthermic Chilean mouse-opossums (Thylamys elegans). We observed higher maximal activities of complexes I and IV during torpor in brain, heart and liver, the most metabolically active organs in mammals. On the contrary, higher enzymatic activities of complexes III were observed during torpor in kidneys and lungs. Moreover, skeletal muscle was the only tissue without significant differences among stages in all complexes evaluated, suggesting no modulation of oxidative capacities of electron transport system components in this thermogenic tissue. In overall, our data suggest that complexes I and IV activity plays a major role in initiation and maintenance of metabolic suppression during torpor in Chilean mouse–opossum, whereas improvement of oxidative capacities in complex III might be critical to sustain metabolic machinery in organs that remains metabolically active during torpor.

      PubDate: 2018-03-19T06:59:32Z
      DOI: 10.1016/j.cbpa.2017.12.014
      Issue No: Vol. 221 (2018)
       
  • Comparison of the organic matrix found in intestinal CaCO3 precipitates
           produced by several marine teleost species
    • Authors: Kevin L. Schauer; Emil A.F. Christensen; Martin Grosell
      Pages: 15 - 23
      Abstract: Publication date: Available online 17 March 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kevin L. Schauer, Emil A.F. Christensen, Martin Grosell
      Marine bony fish poses the unique ability to hydrate from imbibed seawater. They accomplish this, in part, by the precipitation of inorganic carbonate mineral in their intestine, which lowers luminal osmotic pressure and allows for water uptake. It has recently been described that in the Gulf toadfish (Opsanus beta) this Ca(Mg)CO3 precipitation occurs under the regulation of an organic matrix. To date no investigations have aimed to determine if this phenomenon applies more generally to marine fish. Here, intestinally derived precipitates were collected from gray snapper (Lutjanus griseus), white grunt (Haemulon plumieri), European flounder (Platichthys flesus), as well as Gulf toadfish, and their matrices were extracted. The ability of these matrices to regulate CaCO3 production was determined using an in vitro calcification assay, which revealed that the matrix derived from each of the tested species increased precipitation at low concentrations, while inhibiting it at higher concentrations in full agreement with the earlier studies on toadfish. Matrix extracted from European flounder precipitates was then analyzed by mass spectrometry, leading to the identification of over 50 unique proteins. When the identities of these proteins were compared to previous investigation of toadfish precipitate matrix, nearly 35% were found to overlap between the flounder and toadfish analyses, suggesting conserved mechanisms of precipitation control. The effects of using different sodium hypochlorite (NaOCl) solutions during precipitate purification on the resulting organic matrix are also discussed.

      PubDate: 2018-03-19T06:59:32Z
      DOI: 10.1016/j.cbpa.2018.03.007
      Issue No: Vol. 221 (2018)
       
  • A comparison of hatchery-rearing in exercise to wild animal physiology and
           reflex behavior in Aplysia californica
    • Authors: Lynne A. Fieber; Nicholas S. Kron; Justin B. Greer; Hailey Rooney; Rachel A. Prostko; John D. Stieglitz; Martin Grosell; Phillip R. Gillette
      Pages: 24 - 31
      Abstract: Publication date: Available online 17 March 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lynne A. Fieber, Nicholas S. Kron, Justin B. Greer, Hailey Rooney, Rachel A. Prostko, John D. Stieglitz, Martin Grosell, Phillip R. Gillette
      Aplysia californica was hatchery-reared in two turbulence protocols intended to imitate the intermittent turbulence of the native habitat and to promote development of the foot muscle from the exercise of adhering to the substrate. Hatchery-reared animals in turbulence regimes were compared to siblings reared in quiet water, and to wild animals, using noninvasive assessments of the development of the foot muscle. The objective was to learn if the turbulence-reared phenotype mimicked laboratory-targeted aspects of the wild phenotype, that is, reflex behavior, swim tunnel performance, and resting oxygen consumption (MO2). No group exhibited different MO2. MO2 values for all of the compared groups of animals followed the power law, with an exponent of 0.69, consistent with this relationship throughout the animal kingdom. Turbulence-induced exercise did not affect the righting reflex or the tail withdrawal reflex, standard behavioral tests that involve the foot muscle, compared to quiet water-reared siblings. Wild individuals had significantly shorter time-to-right than all hatchery reared animals, however, wild animals did not perform better in flume tests. That turbulence-reared hatchery- or wild animals lacked superior in flume performance suggests that this species may shelter from intertidal wave energy to remain near its optimal feeding areas.

      PubDate: 2018-03-19T06:59:32Z
      DOI: 10.1016/j.cbpa.2018.03.006
      Issue No: Vol. 221 (2018)
       
  • Characterization of lipid metabolism genes and the influence of fatty acid
           supplementation in the hepatic lipid metabolism of dusky grouper
           (Epinephelus marginatus)
    • Authors: Bruno C. Araújo; Nicholas M. Wade; Paulo H. de Mello; Jandyr de A. Rodrigues-Filho; Carlos E.O. Garcia; Mariana F. de Campos; Natasha A. Botwright; Diogo T. Hashimoto; Renata G. Moreira
      Pages: 1 - 9
      Abstract: Publication date: Available online 10 February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Bruno C. Araújo, Nicholas M. Wade, Paulo H. de Mello, Jandyr de A. Rodrigues-Filho, Carlos E.O. Garcia, Mariana F. de Campos, Natasha A. Botwright, Diogo T. Hashimoto, Renata G. Moreira
      Dusky grouper is an important commercial fish species in many countries, but some factors such as overfishing has significantly reduced their natural stocks. Aquaculture emerges as a unique way to conserve this species, but very little biological information is available, limiting the production of this endangered species. To understand and generate more knowledge about this species, liver transcriptome sequencing and de novo assembly was performed for E. marginatus by Next Generation Sequencing (NGS). Sequences obtained were used as a tool to validate the presence of key genes relevant to lipid metabolism, and their expression was quantified by qPCR. Moreover, we investigated the influence of supplementing different dietary fatty acids on hepatic lipid metabolism. The results showed that the different fatty acids added to the diet dramatically changed the gene expression of some key enzymes associated with lipid metabolism as well as hepatic fatty acid profiles. Elongase 5 gene expression was shown to influence intermediate hepatic fatty acid elongation in all experimental groups. Hepatic triglycerides reflected the diet composition more than hepatic phospholipids, and were characterized mainly by the high percentage of 18:3n3 in animals fed with a linseed oil rich diet. Results for the saturated and monounsaturated fatty acids suggest a self-regulatory potential for retention and oxidation processes in liver, since in general the tissues did not directly reflect these fatty acid diet compositions. These results indicated that genes involved in lipid metabolism pathways might be potential biomarkers to assess lipid requirements in the formulated diet for this species.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.018
      Issue No: Vol. 219-220 (2018)
       
  • The osmorespiratory compromise in rainbow trout (Oncorhynchus mykiss): The
           effects of fish size, hypoxia, temperature and strenuous exercise on gill
           diffusive water fluxes and sodium net loss rates
    • Authors: John O. Onukwufor; Chris M. Wood
      Pages: 10 - 18
      Abstract: Publication date: Available online 14 February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): John O. Onukwufor, Chris M. Wood
      In the context of the osmorespiratory compromise, hypoxia and temperature have been little studied relative to exercise, and diffusive water flux rates (as assessed by 3H2O efflux) have received almost no attention. We investigated the effects of fish size, hypoxia, exercise and acute temperature increase on diffusive water flux rates and net sodium loss rates in juvenile rainbow trout. Trout weighing 13–50 g were used to determine the effects of fish size under normoxia. Thereafter 25–50 g trout were selected to assess the effects of different hypoxia levels (3.15, 5.25 and 8.40 KPa), time course of hypoxia (1 h 8.40 KPa, 3 h 8.40 KPa, 1 h 8.40 KPa +1 h normoxic recovery, and 1 h 8.40 KPa + 3 h normoxic recovery), strenuous exercise (5 min) and acute temperature challenge (transfer from 8 °C to 13 °C or to 18 °C). Small fish (13 g) had higher diffusive water flux rates than larger fish, turning over >100% of their fractional body water pool per hour against 34% per hour for 50 g fish. Hypoxic exposure exerted a biphasic effect, increasing the diffusive water flux rate at 8.40 KPa and 5.25 KPa, while returning it to control levels at 3.15 KPa. All the levels of hypoxia increased net Na+ loss. One hour hypoxia (8.40 KPa) increased diffusive water flux rate while prolonged 3 h hypoxia (8.40 KPa), and short or prolonged normoxic recovery returned diffusive water flux rates to control levels. All the treatments over the time course of hypoxia and normoxic recovery increased net Na+ loss rates. Strenuous exercise increased both the diffusive water flux and net Na+ loss rates. Acute temperature rise increased diffusive water flux rates, with Q10 values of 4.03 for 8 to 13 °C and 2.16 for 8 to 18 °C, but the net Na+ loss rate did not change. There was no significant correlation between diffusive water flux rate and net Na+ loss rates at different hypoxia levels, over the course of hypoxia and normoxic recovery, or during acute temperature stress. In contrast, we observed a significant correlation between diffusive water flux and net Na+ loss rates following exercise. Overall, diffusive water flux and sodium loss were regulated differently during acute temperature challenge and hypoxia, while following exercise the two parameters were regulated in a similar fashion.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.02.002
      Issue No: Vol. 219-220 (2018)
       
  • The levels of oxidative stress and antioxidant capacity in hibernating
           Nanorana parkeri
    • Authors: Yonggang Niu; Wangjie Cao; Yaofeng Zhao; Haotian Zhai; Yao Zhao; Xiaolong Tang; Qiang Chen
      Pages: 19 - 27
      Abstract: Publication date: Available online 14 February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Yonggang Niu, Wangjie Cao, Yaofeng Zhao, Haotian Zhai, Yao Zhao, Xiaolong Tang, Qiang Chen
      The effect of hibernation on oxidative stress and antioxidant defenses was assessed in the frog Nanorana parkeri which inhabits the southern Tibetan Plateau. We compared the indices of oxidative stress (GSSG/GSH), the degree of oxidative damage (content of carbonyl proteins and lipid peroxide products) and the activities of antioxidant enzymes (SOD, CAT, GPx, GST and GR) in liver, brain, heart and muscle of N. parkeri sampled during summer and winter. Obtained results showed that hibernation induced a significant decrease in the levels of GSH in heart, liver, and muscle, while the ratio of GSSG/GSH markedly increased in all tissues except for muscle. Regarding oxidative damage, significant increases in TBARS were observed in all tissues of N. parkeri in the midst of hibernation, and the lipid peroxides levels also clearly elevated in these tissues except the liver. In liver and brain, the levels of carbonyl proteins were significantly higher in winter relative to summer. Additionally, the activity of antioxidant enzymes obviously reduced in the liver of hibernating N. parkeri. The total antioxidant capacity was also significantly lower in all tissues during winter than summer. In conclusion, hibernation in N. parkeri induced oxidative stress which was supported by oxidative damage to lipid and protein with suppression of antioxidant defense.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.02.003
      Issue No: Vol. 219-220 (2018)
       
  • Lipophorin receptor regulates Nilaparvata lugens fecundity by promoting
           lipid accumulation and vitellogenin biosynthesis
    • Authors: Kai Lu; Xia Chen; Yue Li; Wenru Li; Qiang Zhou
      Pages: 28 - 37
      Abstract: Publication date: Available online 21 February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kai Lu, Xia Chen, Yue Li, Wenru Li, Qiang Zhou
      Insect lipophorin receptor (LpR) belongs to the low-density lipoprotein receptor (LDLR) superfamily and plays an essential role in fecundity by mediating the incorporation of lipophorin into developing oocytes. Here we report the identification and characterization of a full-length cDNA encoding a putative LpR from the brown planthopper, Nilaparvata lugens. The deduced amino acid sequence of NlLpR possesses the conserved structural motifs of LDLR family members, and displays a high degree of similarity with sequences from other insect LpRs. NlLpR is transcribed throughout oogenesis with its maximum level on day 7 after adult female emergence. NlLpR is highly expressed in the fat body and ovary, with relative low levels in the head, epidermis and midgut. Knockdown of NlLpR using double-stranded RNA (dsRNA) led to decreased triacylglycerol (TAG) content, retarded development of ovaries and decreased fecundity. Further functional analyses revealed that NlLpR works through nutritional signaling pathway-dependent activation of S6 kinase to regulate vitellogenin (Vg) biosynthesis during vitellogenesis and oocyte development. Disrupting of ecdysone receptor (EcR) expression and 20-hydroxyecdysone (20E) topical application demonstrated that NlLpR is regulated by ecdysone at transcript level. These results suggest that LpR is essential for Vg synthesis in the fat body and lipid uptake by developing oocytes, thus playing a critical role in insect reproduction.

      PubDate: 2018-02-26T03:17:50Z
      DOI: 10.1016/j.cbpa.2018.02.008
      Issue No: Vol. 219-220 (2018)
       
  • The physiological stress response of the Atlantic stingray (Hypanus
           sabinus) to aerial exposure
    • Authors: Faith N. Lambert; Jason R. Treberg; W. Gary Anderson; Catherine Brandt; Andrew N. Evans
      Pages: 38 - 43
      Abstract: Publication date: Available online 23 February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Faith N. Lambert, Jason R. Treberg, W. Gary Anderson, Catherine Brandt, Andrew N. Evans
      Although secondary stress physiology of elasmobranchs is fairly well studied, gaps remain in our understanding of species differences, including stress recovery. We examined the physiological stress response to air exposure in Atlantic stingrays (Hypanus sabinus) using a serial sampling method requiring minimal handling. Many elasmobranch stress studies exclusively quantify glucose, although there is evidence that elasmobranchs are unusually reliant on ketone bodies. Therefore, we also tested the hypothesis that ketone bodies play a significant role in the elasmobranch stress response by examining plasma β-hydroxybutyrate. Plasma osmolality, urea, trimethylamine-N-oxide, and a suite of ions were also measured to characterize departures from homeostasis due to air exposure. H. sabinus were exposed to air for 30 min and serially sampled at 0, 15, and 30 min, as well as 48 h after the stressor to assess the extent of recovery. Blood lactate and acidosis increased significantly during the stressor and returned to basal levels by 48 h. Glucose values were significantly affected, with the highest values observed at 48 h, suggesting that animals were not fully recovered as initially indicated by other metrics. Average plasma β-hydroxybutyrate was unaffected by the stressor. This suggests that ketone bodies may not be a major fuel source used during acute stress, at least in the timeframe examined.

      PubDate: 2018-02-26T03:17:50Z
      DOI: 10.1016/j.cbpa.2018.02.009
      Issue No: Vol. 219-220 (2018)
       
  • Hypoxia inhibits the regulatory volume decrease in red blood cells of
           common frog (Rana temporaria)
    • Authors: Aleksandra Y. Andreyeva; Elizaveta A. Skverchinskaya; Stepan Gambaryan; Aleksander A. Soldatov; Igor V. Mindukshev
      Pages: 44 - 47
      Abstract: Publication date: May 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volumes 219–220
      Author(s): Aleksandra Y. Andreyeva, Elizaveta A. Skverchinskaya, Stepan Gambaryan, Aleksander A. Soldatov, Igor V. Mindukshev
      Red blood cells of vertebrates can restore their cellular volume after hyposmotic swelling. The process strictly depends on oxygen availability in the environment. However, the role of hemoglobin in regulation of cell volume recovery is not clear yet. Little is known about the osmotic reactions and regulatory volume decrease of amphibian red blood cells. We investigated volume recovery process in oxygenated (oxyhemoglobin concentration 97 ± 3% of total hemoglobin) deoxygenated (96 ± 2% of deoxyhemolobin) and oxidized (47 ± 2% of methemoglobin, 41 ± 3% of deoxyhemoglobin) red blood cells of common frog (Rana temporaria) after hyposmotic swelling. Using the low-angle light scattering method we demonstrated the regulatory volume decrease in oxygenated cells and showed that the process was eliminated in hypoxic conditions. Reoxygenation of hypoxic cells restored the regulatory volume decrease. Oxidation of cellular hemoglobin to methemoglobin inhibited the volume recovery response in hyposmotically swollen oxygenated and reoxygenated hypoxic cells.

      PubDate: 2018-03-07T05:27:58Z
      DOI: 10.1016/j.cbpa.2018.02.016
      Issue No: Vol. 219-220 (2018)
       
  • Seasonal variation of pituitary gonadotropin subunit, brain-type aromatase
           and sex steroid receptor mRNAs, and plasma steroids during gametogenesis
           in wild sablefish
    • Authors: José M. Guzmán; J. Adam Luckenbach; Denis A.M. da Silva; Edward S. Hayman; Gina M. Ylitalo; Frederick W. Goetz; Penny Swanson
      Pages: 48 - 57
      Abstract: Publication date: Available online 26 February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): José M. Guzmán, J. Adam Luckenbach, Denis A.M. da Silva, Edward S. Hayman, Gina M. Ylitalo, Frederick W. Goetz, Penny Swanson
      Pituitary-hormone signaling plays critical roles in the onset and progression of gametogenesis in vertebrates. This study characterized expression patterns of pituitary gonadotropin beta-subunits (fshb and lhb), brain-type aromatase (cyp19a1b), androgen (ar1, ar2) and estrogen receptors (esr1, esr2a, esr2b), and changes in plasma steroid levels by liquid chromatography/tandem mass spectrometry in wild sablefish (Anoplopoma fimbria, order Scorpaeniformes) during a complete reproductive cycle. Transcripts for fshb increased during early gametogenesis and peaked in late vitellogenic females and late recrudescent males, while expression of lhb reached maximum levels in periovulatory and spermiating fish. Pituitary levels of cyp19a1b and ar1 were strongly correlated with those of lhb in females and males, increasing during gametogenesis and reaching maximum levels prior to spawning. By contrast, expression of ar2, and the three estrogen receptors differed between female and male sablefish. 17β-estradiol (E2) was the dominant steroid in females during vitellogenesis, while a range of at least 6 steroids (11β-hydroxyandrostenedione, testosterone [T], E2, 11-ketotestosterone, 11-deoxycortisol, and 17α,20β,21-trihydroxyprogesterone) were detected at similar levels in males during testicular development. Prior to spawning, a marked increase in 4-androstenedione, T, 11KT and E2 was found in both periovulatory females and spermiating males. In conclusion, the concomitant changes in plasma androgen levels and pituitary ar1 expression during gametogenesis suggest a specific role for androgens in pituitary hormone regulation of reproduction in sablefish. Further, our data highlight the importance of E2 during final stages of maturation in this species, which may regulate the transcription of pituitary lhb in a paracrine fashion.

      PubDate: 2018-03-07T05:27:58Z
      DOI: 10.1016/j.cbpa.2018.02.010
      Issue No: Vol. 219-220 (2018)
       
  • Effect of incubation temperature on neuropeptide Y and neuropeptide Y
           receptors in turkey and chicken satellite cells
    • Authors: Daniel L. Clark; Janet L. McCormick; Sandra G. Velleman
      Pages: 58 - 66
      Abstract: Publication date: Available online 2 March 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel L. Clark, Janet L. McCormick, Sandra G. Velleman
      Neuropeptide Y (NPY) is an appetite stimulating peptide released from the central nervous system and impacts the function of many different cell types. A recent transcriptome study showed that NPY expression was altered when turkey breast muscle satellite cells were incubated at low or high temperatures, suggesting NPY may mediate temperature effects on satellite cells. However, to date minimal information exists describing the expression and function of NPY in satellite cells. The objective of this study was to determine how temperature impacts NPY and NPY receptor gene expression in satellite cells isolated from turkeys and chickens with differing genetic lineages. Two broiler and two turkey breast muscle satellite cell lines were incubated at 35, 38 or 41 °C during proliferation and differentiation. In both turkey lines, NPY, and receptors NPY2R and NPY5R expression increased at elevated temperatures after 72 h of proliferation. During differentiation NPY and NPY5R expression increased in both turkey lines with higher temperatures, whereas NPY2R was minimally affected by temperature. In contrast, in both chicken cell lines there were few significant differences for NPY and NPY receptor expression across temperature during proliferation. During differentiation, the temperature effect was different in the two chicken cell lines. In the BPM8 chicken line, there were few differences in NPY and NPY receptors across temperature; whereas elevated temperatures increased NPY, NPY2R, and NPY5R expression in the 708 line. The differences between turkey and chicken lines suggest NPY has species specific satellite cell functions in response to heat stress.

      PubDate: 2018-03-07T05:27:58Z
      DOI: 10.1016/j.cbpa.2018.02.014
      Issue No: Vol. 219-220 (2018)
       
  • Cortisol and melatonin in the cutaneous stress response system of fish
    • Authors: Ewa Kulczykowska; Hanna Kalamarz-Kubiak; Magdalena Gozdowska; Ewa Sokołowska
      Pages: 1 - 7
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Ewa Kulczykowska, Hanna Kalamarz-Kubiak, Magdalena Gozdowska, Ewa Sokołowska
      The stress hormone cortisol, together with antioxidants, melatonin (Mel) and its biologically active metabolites, 5-methoxykynuramines, including AFMK, set up a local stress response system in mammalian skin. Our in vitro study of the European flounder (Platichthys flesus) was designed to examine whether Mel and AFMK would respond to cortisol while a glucocorticoid is added to the incubation medium. The concentrations of cortisol in the incubation medium mimic plasma cortisol levels seen in fish exposed to different types of stresses such as handling, confinement, high density, food-deprivation or air-exposure. We measured Mel and AFMK in skin explants and culture media using high-performance liquid chromatography (HPLC) with fluorescence detection. We also analysed melanosome response (dispersion/aggregation) in the explants subjected to the different treatments. Cortisol stimulated the release of Mel and AFMK from skin explants in a dose-dependent manner. Melanosome dispersion and a darkening of the skin explants were observed after incubation with cortisol. This study is the first to demonstrate the interrelationship between cortisol and Mel/AFMK in fish skin. Our data strongly suggest that the cutaneous stress response system (CSRS) is present in fish. The question remains whether Mel, AFMK or cortisol are synthetized locally in fish skin and/or transported by the bloodstream. The presence of the CSRS should be taken into account during elaboration of new indicators of fish welfare both in aquaculture and in the wild.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.003
      Issue No: Vol. 218 (2018)
       
  • Ca2+ levels in Daphnia hemolymph may explain occurrences of daphniid
           species along recent Ca gradients in Canadian soft-water lakes.
    • Authors: Andrea C. Durant; Martha P. Celis-Salgado; Shayan Ezatollahpour; Norman D. Yan; Shelley E. Arnott; Andrew Donini
      Pages: 8 - 15
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Andrea C. Durant, Martha P. Celis-Salgado, Shayan Ezatollahpour, Norman D. Yan, Shelley E. Arnott, Andrew Donini
      Calcium levels are declining in eastern North American and western European lakes. This widespread issue is affecting the composition of crustacean zooplankton communities, as the presence and abundance of several calcium-rich daphniid species are declining, while two other daphniids, D. catawba and D. ambigua, that apparently tolerate low calcium environments, are prospering. The physiological basis for low calcium tolerance of these daphniids is unknown. In this study the presence of one Ca-rich (D. pulicaria) and one Ca-poor (D. ambigua) daphniid species in Canadian Shield lakes is assessed in relation to lake water Ca levels. The occurrence of D. ambigua was independent of Ca levels in Ontario lakes, whereas D. pulicaria was more likely to occur in lakes with relatively more Ca. In the laboratory, D. ambigua maintained lower levels of hemolymph Ca2+ across a range of low Ca levels (0.7 to 7 mg l−1) compared with D. pulicaria. The hemolymph pH remained steady across this Ca gradient in D. ambigua while it was significantly more acidic in D. pulicaria in the two lowest Ca treatments. While Ca2+ uptake was observed adjacent to the surface of D. ambigua individuals, Ca2+ loss was observed for D. pulicaria assayed under moderately high Ca levels. Based on these observations we propose that D. ambigua is able to survive in low Ca lakes by maintaining low free ionic Ca2+ levels in the hemolymph which minimizes the Ca gradient across the body wall in low Ca water thus limiting overall Ca loss and facilitating Ca2+ uptake.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.009
      Issue No: Vol. 218 (2018)
       
  • Effects of the acclimation to high salinity on intestinal ion and peptide
           transporters in two tilapia species that differ in their salinity
           tolerance
    • Authors: Tapan Kumar Chourasia; Helena D'Cotta; Jean-Francois Baroiller; Tatiana Slosman; Avner Cnaani
      Pages: 16 - 23
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Tapan Kumar Chourasia, Helena D'Cotta, Jean-Francois Baroiller, Tatiana Slosman, Avner Cnaani
      Tilapiine species, widely distributed across habitats with diverse water salinities, are important to aquaculture as well as a laboratory model. The effects of water salinity on two tilapia species, that differ in their salinity tolerance, was evaluated. Oreochromis niloticus reared in brackish-water, showed a significant decrease in growth and feed efficiency, whereas O. mossambicus reared in seawater did not show any significant changes. The expression and activity of Na+/K+-ATPase (NKA), V-type H+-ATPase (VHA) and carbonic anhydrase (CA), as well as expression levels of genes encoding two HCO3 − and three peptide transporters (nbc1, slc26a6, slc15a1a, slc15a1b and slc15a2) were measured in three intestinal sections of these two species, grown in freshwater and brackish/sea-water. Overall, the spatial distribution along the intestine of the genes examined in this study was similar between the two species, with the exception of tcaIV. The salinity response, on the other hand, varied greatly between these species. In O. mossambicus, there was a salinity-dependent increased expression of most of the examined genes (except slc26a6 and slc15a2), while in O. niloticus the expression of most genes did not change, or even decreased (tcaIV, nbc1 and slc15a1b). This study highlighted differences in the intestinal response to salinity acclimation between closely- related species that differ in their salinity tolerance. O. mossambicus, which has a high salinity tolerance, showed expression patterns and responses similar to marine species, and differed from the low-salinity-tolerance O. niloticus, which showed a response that differed from the accepted models, that are based on marine and diadromous fishes.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.004
      Issue No: Vol. 218 (2018)
       
  • Hematology from embryo to adult in the bobwhite quail (Colinus
           virginianus): Differential effects in the adult of clutch, sex and hypoxic
           incubation
    • Authors: Josele Flores-Santin; Maria Rojas Antich; Hiroshi Tazawa; Warren W. Burggren
      Pages: 24 - 34
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Josele Flores-Santin, Maria Rojas Antich, Hiroshi Tazawa, Warren W. Burggren
      Hematology and its regulation in developing birds have been primarily investigated in response to relatively short-term environmental challenges in the embryo. Yet, whether any changes induced in the embryo persist into adulthood as a hematological form of “fetal programming” is unknown. We hypothesized that: 1) chronic as opposed to acute hypoxic incubation will alter hematological respiratory variables in embryos of bobwhite quail (Colinus virginianus), and 2) alterations first appearing in the embryo will persist into hatchlings through into adulthood. To test these hypotheses, we first developed an embryo-to-adult profile of normal hematological development by measuring hematocrit (Hct), red blood cell concentration ([RBC]), hemoglobin concentration ([Hb]), mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration, as well plasma osmolality. Hct, [RBC] and [Hb] in normoxic-incubated birds (controls) steadily increased from ~22%, ~1.6 × 106 μL−1 and ~7 g% in day 12 embryos to almost double the values at maturity in adult birds. Both cohort and sex affected hematology of normoxic-incubated birds. A second population, incubated from day 0 (d0) in 15% O2, surprisingly revealed little or no significant difference from controls in hematology in embryos. In hatchlings and adults, hypoxic incubation caused no significant modification to any variables. Compared to major hematological effects caused by hypoxic incubation in chickens, the hematology of the bobwhite quail embryo appears to be minimally affected by hypoxic incubation, with very few effects induced during hypoxic incubation actually persisting into adulthood.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.005
      Issue No: Vol. 218 (2018)
       
  • Activation of free sperm and dissociation of sperm bundles
           (spermatozeugmata) of an endangered viviparous fish, Xenotoca eiseni
    • Authors: Yue Liu; Huiping Yang; Leticia Torres; Terrence R. Tiersch
      Pages: 35 - 45
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Yue Liu, Huiping Yang, Leticia Torres, Terrence R. Tiersch
      Knowledge of sperm motility activation for viviparous fishes has been limited to study of several species in Poeciliidae, and the dissociation of sperm bundles is even less understood. The goal of this study was to use the endangered Redtail Splitfin (Xenotoca eiseni) as a model to investigate the activation of sperm from viviparous fishes by study of free sperm and spermatozeugmata (unencapsulated sperm bundles). The specific objectives were to evaluate the effects of: (1) osmotic pressure and refrigerated storage (4 °C) on activation of free sperm, (2) osmotic pressure, ions, and pH on dissociation of spermatozeugmata, and (3) CaCl2 concentration and pH on sperm membrane integrity. Free sperm were activated in Ca2+-free Hanks' balanced salt solution at 81–516 mOsmol/kg. The highest motility (19 ± 6%) was at 305 mOsmol/kg and swim remained for 84 h. Glucose (300–700 mOsmol/kg), NaCl (50–600 mOsmol/kg), and KCl, MgCl2, and MnCl2 at 5–160 mM activated sperm within spermatozeugmata, but did not dissociate spermatozeugmata. CaCl2 at 5–160 mM dissociated spermatozeugmata within 10 min. Solutions of NaCl-NaOH at pH 11.6 to 12.4 dissociated spermatozeugmata within 1 min. The percentage of viable cells had no significant differences (P = 0.2033) among different concentrations of CaCl2, but it was lower (P < 0.0001) at pH 12.5 than at pH between 7.0 and 12.0. Overall, this study provided a foundation for quality evaluation of sperm and spermatozeugmata from livebearing fishes, and for development of germplasm repositories for imperiled goodeids.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.006
      Issue No: Vol. 218 (2018)
       
  • Maternal allocation of carotenoids to eggs in an Anolis lizard
    • Authors: Beth A. Reinke; Yasmeen Erritouni; Ryan Calsbeek
      Pages: 56 - 62
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Beth A. Reinke, Yasmeen Erritouni, Ryan Calsbeek
      The maternal allocation of carotenoids to eggs has been widely documented and manipulated. However, it is often assumed that the sole adaptive value of this allocation is to increase offspring fitness. Because carotenoids can be pro-oxidants or antioxidants depending on their concentrations and their chemical environment (i.e. presence of other antioxidants), dams may need to dispose of excess carotenoids upon depletion of other antioxidants to prevent oxidative damage. Additionally, the amount of carotenoids deposited in eggs may be dependent on male traits such as quality and coloration. We evaluated these two non-mutually exclusive hypotheses for carotenoid allocation to eggs and assessed paternal effects by supplementing male and female brown anole lizards, Anolis sagrei, with dietary carotenoids or with a combination of carotenoids and vitamin C. We found significant differences in the antioxidant capacities of fertilized and unfertilized eggs produced by female lizards, but the treatment did not affect the antioxidant capacity or carotenoid content of eggs. However, the carotenoid concentration of unfertilized eggs from carotenoid-supplemented females was significantly higher than eggs from the control group. Male coloration and body size did not affect the antioxidant capacity or carotenoid content of the eggs. Carotenoids may be allocated to unfertilized eggs to offset oxidative damage to the dam, with a neutral effect on offspring, rather than to solely provide antioxidant benefits to offspring as has been widely assumed.

      PubDate: 2018-02-15T00:35:16Z
      DOI: 10.1016/j.cbpa.2018.01.014
      Issue No: Vol. 218 (2018)
       
  • How does school size affect tail beat frequency in turbulent water'
    • Authors: Lewis G. Halsey; Serena Wright; Anita Racz; Julian D. Metcalfe; Shaun S. Killen
      Pages: 63 - 69
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Lewis G. Halsey, Serena Wright, Anita Racz, Julian D. Metcalfe, Shaun S. Killen
      The energy savings experienced by fish swimming in a school have so far been investigated in an near-idealised experimental context including a relatively laminar water flow. The effects of explicitly turbulent flows and different group sizes are yet to be considered. Our repeated-measures study is a first step in addressing both of these issues: whether schooling is more energetically economical for fish when swimming in a quantified non-laminar flow and how this might be moderated by group size. We measured tail beat frequency (tbf) in sea bass swimming in a group of 3 or 6, or singly. Video data enabled us to approximately track the movements of the fish during the experiments and in turn ascertain the water flow rates and turbulence levels experienced for each target individual. Although the fish exhibited reductions in tbf during group swimming, which may indicate some energy savings, these savings appear to be attenuated, presumably due to the water turbulence and the movement of the fish relative to each other. Surprisingly, tbf was unrelated to flow rate when the fish were swimming singly or in a group of three, and decreased with increasing flow rates when swimming in a group of six. However, the fish increased tbf in greater turbulence at all group sizes. Our study demonstrates that under the challenging and complex conditions of turbulent flow and short-term changes in school structure, group size can moderate the influences of water flow on a fish's swimming kinematics, and in turn perhaps their energy costs. Summary statement The energy savings that sea bass experience from schooling are affected by flow speed or turbulence, moderated by group size

      PubDate: 2018-03-07T05:27:58Z
      DOI: 10.1016/j.cbpa.2018.01.015
      Issue No: Vol. 218 (2018)
       
  • Fatty acid composition in native bees: Associations with thermal and
           feeding ecology
    • Authors: Susma Giri; Daniel C. Rule; Michael E. Dillon
      Pages: 70 - 79
      Abstract: Publication date: April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 218
      Author(s): Susma Giri, Daniel C. Rule, Michael E. Dillon
      Fatty acid (FA) composition of lipids plays a crucial role in the functioning of lipid-containing structures in organisms and may be affected by the temperature an organism experiences, as well as its diet. We compared FA composition among four bee genera: Andrena, Bombus, Megachile, and Osmia which differ in their thermal ecology and diet. Fatty acid methyl esters (FAME) were prepared by direct transesterification with KOH and analyzed using gas-liquid chromatography with a flame ionization detector. Sixteen total FAs ranging in chain length from eight to 22 carbon atoms were identified. Linear discriminant analysis separated the bees based on their FA composition. Andrena was characterized by relatively high concentrations of polyunsaturated FAs, Bombus by high monounsaturated FAs and Megachilids (Megachile and Osmia) by relatively high amounts of saturated FAs. These differences in FA composition may in part be explained by variation in the diets of these bees. Because tongue (proboscis) length may be used as a proxy for the types of flowers bees may visit for nectar and pollen, we compared FA composition among Bombus that differed in proboscis length (but have similar thermal ecology). A clear separation in FA composition within Bombus with varying proboscis lengths was found using linear discriminant analysis. Further, comparing the relationship between each genus by cluster analysis revealed aggregations by genus that were not completely separated, suggesting potential overlap in dietary acquisition of FAs.

      PubDate: 2018-03-07T05:27:58Z
      DOI: 10.1016/j.cbpa.2018.01.013
      Issue No: Vol. 218 (2018)
       
  • Carry-over effects modulated by salinity during the early ontogeny of the
           euryhaline crab Hemigrapsus crenulatus from the Southeastern Pacific
           coast: Development time and carbon and energy content of offspring
    • Authors: Ángel Urzúa; Miguel Bascur; Fabián Guzmán; Mauricio Urbina
      Pages: 55 - 62
      Abstract: Publication date: March 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 217
      Author(s): Ángel Urzúa, Miguel Bascur, Fabián Guzmán, Mauricio Urbina
      Hemigrapsus crenulatus is a key species of coastal and estuarine ecosystems in the Southeastern Pacific and New Zealand. Since the gravid females-and their embryos-develop under conditions of variable salinity, we propose that low external salinity will be met with an increase in energy expenditures in order to maintain osmoregulation; subsequently, the use of energy reserves for reproduction will be affected. In this study, we investigate in H. crenulatus whether 1) the biomass and energy content of embryos is influenced by salinity experienced during oogenesis and embryogenesis and 2) how variation in the biomass and energy content of embryos affects larval energetic condition at hatching. Here at low salinity (5PSU), egg-bearing females experienced massive and frequent egg losses, and therefore the development of their eggs during embryogenesis was not completed. In turn, at intermediate and high salinity (15 and 30PSU) embryogenesis was completed, egg development was successful, and larvae were obtained. Consistently, larvae hatched from eggs produced and incubated at high salinity (30PSU) were larger, had higher dry weight, and had increased carbon content and energy than larvae hatched from eggs produced at intermediate salinity (15PSU). From these results, it is seen that the size and biomass of early life stages of H. crenulatus can be affected by environmental salinity experienced during oogenesis and embryogenesis, and this variation can then directly affect the energetic condition of offspring at birth. Therefore, this study reveals a “cascade effect” modulated by salinity during the early ontogeny.

      PubDate: 2018-01-09T19:45:16Z
      DOI: 10.1016/j.cbpa.2018.01.001
      Issue No: Vol. 217 (2018)
       
  • Evidence for retinoic acid involvement in the regulation of vitellogenesis
           in the fresh water edible crab, Oziotelphusa senex senex
    • Abstract: Publication date: August 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 222
      Author(s): B.P. Girish, CH. Swetha, M. Srilatha, M. Hemalatha, P. Sreenivasula Reddy
      The possible involvement of 13-cis retinoic acid (CRA) in the regulation of ovarian development in Oziotelphusa senex senex was investigated. Injection of CRA, into avitellogenic crabs significantly increased ovarian index, oocyte diameter and ovarian vitellogenin levels. Injection of CRA also resulted in a significant increase in the secretory rates of mandibular organs and Y-organs and circulatory levels of the methyl farnesoate and ecdysteroids. Further, administration of CRA into avitellogenic crabs produced higher amounts of Retinoid X Receptor, Ecdysteroid Receptor, E75 and vitellogenin mRNAs in the hepatopancreas. Mandibular organ and Y-organ explants isolated from avitellogenic crabs secreted more of methyl farnesoate and ecdysteroids respectively when incubated with CRA. Taken together, these observations led us to hypothesize that CRA stimulates ecdysteroidogenesis and methyl farnesoate synthesis, up-regulates EcR, RXR and E75 expression in hepatopancreas, which then induces vitellogenin gene expression. Vitellogenin is subsequently taken up from hemolymph by ovaries ensuing in ovarian maturation.

      PubDate: 2018-04-18T10:19:10Z
       
  • Phylogenetic analysis of cnidarian peroxiredoxins and stress-responsive
           expression in the estuarine sea anemone Nematostella vectensis
    • Abstract: Publication date: July 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 221
      Author(s): Rebecca R. Helm, Maria Laura Martín-Díaz, Ann M. Tarrant
      Peroxiredoxins (PRXs) are a family of antioxidant enzymes present in all domains of life. To date, the diversity and function of peroxiredoxins within animals have only been studied in a few model species. Thus, we sought to characterize peroxiredoxin diversity in cnidarians and to gain insight into their function in one cnidarian–the sea anemone Nematostella vectensis. Phylogenetic analysis using all six known PRX subfamilies (PRX1–4, PRX5, PRX6, PRXQ/AHPE1, TPX, BCP-PRXQ) revealed that like bilaterians, cnidarians contain representatives from three subfamilies (PRX1–4, PRX5, PRX6). Within the PRX1–4 subfamily, cnidarian sequences fall into two clades: PRX4, and a cnidarian-specific clade, which we term CNID-PRX. This phylogenetic analysis demonstrates that the three PRX subfamilies present in Bilateria were also present in the last common ancestor of the Cnidaria and Bilateria, and further that diversification of the PRX1–4 subfamily has occurred within the cnidarian lineage. We next examined the impact of decreased salinity, increased temperature, and peroxide exposure on the expression of four prx genes in N. vectensis (cnid-prx, prx4, prx5, and prx6). These genes exhibited unique expression patterns in response to these environmental stressors. Expression of prx4 decreased with initial exposure to elevated temperature, cnid-prx increased with exposure to elevated temperatures as well as with hydrogen peroxide exposure, and expression of all prxs transiently decreased with reduced salinity. Predicted subcellular localization patterns also varied among PRX proteins. Together these results provide evidence that peroxiredoxins in N. vectensis serve distinct physiological roles and lay a groundwork for understanding how peroxiredoxins mediate cnidarian developmental processes and environmental responses.

      PubDate: 2018-04-18T10:19:10Z
       
  • Differential expression of gonadotropin and estrogen receptors and oocyte
           cytology during follicular maturation associated with egg viability in
           European eel (Anguilla anguilla)
    • Abstract: Publication date: July 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 221
      Author(s): Filipa F.G. da Silva, Helge Tveiten, Gersende Maugars, Anne-Gaëlle Lafont, Sylvie Dufour, Josianne G. Støttrup, Elin Kjørsvik, Jonna Tomkiewicz
      In captivity, oogenesis and ovarian follicle maturation in European eel can be induced experimentally using hormonal therapy. The follicle's ability to respond effectively to the induction of maturation and ovulation, resulting in viable eggs, depends on the oocyte stage at the time of induction. We hypothesized that variation in the expression of key hormone receptors in the ovary and size of oocyte lipid droplets are associated with changes in oocyte stage. Thus, we induced ovarian follicle maturation using a priming dose of fish pituitary extract followed by the administration of a 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) injection. Females were then strip-spawned, the eggs were fertilized in vitro, incubated and larval survival was recorded at 3 days post hatch (dph). The expression of gonadotropin receptors (fshr, lhcgr1 and lhcgr2) and estrogen receptors (esr1, esr2a, esr2b, gpera and gperb) was quantified and the size of oocyte lipid droplets measured. Larval survival at 3 dph was used to differentiate high- and low-quality egg batches. Results showed significantly higher abundance of lhcgr1 and esr2a at priming for high-quality egg batches whereas fshr and gperb transcripts were significantly higher at DHP injection for low-quality egg batches. Therefore, high levels of lhcgr1 and esr2a may be important for attaining follicular maturational competence, while high fshr and gperb mRNA levels may indicate inadequate maturational competence. Furthermore, lipid droplet size at DHP and in ovulated eggs was significantly smaller in high-quality egg batches than in low-quality, which indicates that droplet size may be a useful marker of follicular maturational stage.

      PubDate: 2018-04-18T10:19:10Z
       
  • Interactive effects of salinity and temperature acclimation on gill
           morphology and gene expression in threespine stickleback
    • Abstract: Publication date: July 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 221
      Author(s): Taylor C. Gibbons, Tara L. McBryan, Patricia M. Schulte
      Colonization of freshwater habitats from marine environments exposes organisms to novel combinations of temperature and salinity, but little is known about physiological responses to the interactive effects of these stressors. Here, we examined the effects of temperature (14 versus 4 °C) and salinity (11 versus 0.3 ppt) on gill gene expression in marine, anadromous, and freshwater populations of threespine stickleback (Gasterosteus aculeatus). Expression of the epithelial calcium channel was not affected by temperature or salinity, but had significantly higher expression in the freshwater ecotype. The combination of low temperature and low salinity had non-additive effects on the expression of the Na+/H+ exchanger. Fish exposed to the combination of low temperature and low salinity had expression levels similar to fish exposed to either factor in isolation. Expression of Na+,K+-ATPase α-subunit was greater in fish exposed to low temperature and low salinity than in fish exposed to the factors separately, and this effect was the most pronounced in the marine ecotype. We also examined the interactive effects of salinity and temperature on gill morphology in the marine ecotype, and observed non-additive effects. Low temperature increased the size of the interlamellar cell mass in fish held at 11 ppt, but not at 0.3 ppt, and the effect of low salinity was in the opposite direction in fish at high and low temperatures. These data demonstrate interactive effects of temperature and salinity and highlight that overwintering in cold freshwater was likely a physiological challenge for marine stickleback as they colonized freshwater following the last glaciation.

      PubDate: 2018-04-18T10:19:10Z
       
  • Shifts in the relationship between mRNA and protein abundance of gill
           ion-transporters during smolt development and seawater acclimation in
           Atlantic salmon (Salmo salar)
    • Abstract: Publication date: July 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 221
      Author(s): Arne K. Christensen, Amy M. Regish, Stephen D. McCormick
      Smolting Atlantic salmon exhibit a seasonal increase in seawater tolerance that is associated with changes in the abundance of major gill ion-transporter transcripts and proteins. In the present study, we investigate how the transcript and protein abundance of specific ion-transporter isoforms relate to each other during smolt development and seawater acclimation, and how each correlates to seawater tolerance. We show that during smolt development both mRNA and protein abundance of gill Na+/K+-ATPase α1a subunit (NKAα1a) decreased but the decrease in the mRNA was five-times greater than that of the protein. Gill NKAα1b mRNA levels increased only slightly (1.5-fold) throughout development whereas protein abundance increased 30-fold at its peak. Gill Na+/K+/2Cl− co-transporter 1 (NKCC1) increased at the mRNA and protein level (5- and 12-fold) in smolts. The abundance of a gill ion-transporter's mRNA and protein changed in the same direction through development and after seawater transfer, but the changes were not always strongly correlated: NKAα1a (r = 0.768), NKAα1b (r = 0.40), and NKCC1 (r = 0.898). The maintenance of plasma chloride concentration correlated most strongly with the abundance of NKAα1a mRNA, and the ratio of NKAα1b to NKAα1a mRNA and protein. Growth performance after seawater transfer correlated most strongly with the abundance of NKAα1b protein and the ratio of NKAα1b to NKAα1a protein. Our results indicate that the abundance of ion-transporter mRNA and protein do not always correlate well and a decrease in the abundance of gill NKAα1a mRNA and increase in NKAα1b protein are strong predictors of seawater tolerance and growth performance after seawater transfer.

      PubDate: 2018-04-18T10:19:10Z
       
  • Corrigendum to “Respiration-based monitoring of metabolic rate following
           cold-exposure in two invasive Anoplophora species depending on acclimation
           regime” [Comp. Biochem. Physiol. A Vol. 216 (2018) 20-27]
    • Abstract: Publication date: May 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volumes 219–220
      Author(s): M. Javal, A. Roques, G. Roux, M. Laparie


      PubDate: 2018-04-18T10:19:10Z
       
  • Sex-specific transcription and DNA methylation profiles of reproductive
           and epigenetic associated genes in the gonads and livers of breeding
           zebrafish
    • Abstract: Publication date: Available online 12 April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): L.V. Laing, J. Viana, E. Dempster, T.M. Uren Webster, R. van Aerle, J. Mill, E.M. Santos
      Reproduction is an essential process for life and is regulated by complex hormone networks and environmental factors. To date, little is known about the contribution of epigenetic mechanisms to the regulation of reproduction, particularly in lower vertebrates. We used the zebrafish (Danio rerio) model to investigate the sex-specific transcription and DNA methylation profiles for genes involved in the regulation of reproduction and in epigenetic signalling in the livers and gonads. We found evidence for associations between DNA promotor methylation and transcription for esr1 (gonads and female livers), amh (gonads) and dnmt1 (livers). In the liver, esr1 was shown to be significantly over-expressed in females compared to males, and its promoter was significantly hypo-methylated in females compared to males. In the gonads, genes involved in epigenetic processes including dnmt1, dnmt3 and hdac1 were over-expressed in the ovary compared to the testis. In addition, dnmt1 and dnmt3 transcription in the testis was found to be strongly correlated with global DNA methylation. These data provide evidence of the sex-specific epigenetic regulation and transcription of genes involved in reproduction and epigenetic signalling in a commonly used vertebrate model.

      PubDate: 2018-04-18T10:19:10Z
       
  • The impact of acute thermal stress on green mussel Perna viridis:
           Oxidative damage and responses
    • Abstract: Publication date: Available online 11 April 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jing Wang, Bo Dong, Zhen-Xing Yu, Cui-Luan Yao
      Examining the physiological responses of mussels to thermal stress is crucial to evaluate their biogeographic distribution and ability to adapt to a changing climate. In the present study, we investigated the effects of acute cold (8 °C and 15 °C) and heat (35 °C and 42 °C) stress on the mortality rate, reactive oxygen species (ROS) production, malondialdehyde (MDA) content, mitochondrial membrane potential (MMP) and antioxdative responses in the gill tissue of the green mussel species Perna viridis. Our results showed that cold and heat stress induced a temperature-dependent increase in mortality rate. ROS production increased significantly (p < 0.01) after both cold and heat stress. However, the activities of antioxidant enzymes, including SOD, CAT and GSH-Px, were greatly enhanced only after heat stress. In addition, MDA content and MMP increased significantly under both cold and heat stress. The up-regulation of Hsp70 transcripts was only detected after acute stress at 35 °C. However, p38-MAPK phosphorylation levels increased after both cold and heat stress. In addition, a moderate activation of caspase-3 was found after mussels were exposed to 8 °C and 42 °C stress. Our results suggest that both extreme cold and heat stress could induce ROS production in the gill tissue of P. viridis, which might result in lipid peroxidation and mitochondria dysfunction. Antioxidative enzymes and Hsp70 might be important in the heat stress response of animals, whereas p38-MAPK might be crucial in the acute response to both cold and heat stress. However, caspase-3 activation might be very weak under both cold and heat stress.

      PubDate: 2018-04-18T10:19:10Z
       
  • The effects of morphine on gas exchange, ventilation pattern and
           ventilatory responses to hypercapnia and hypoxia in dwarf caiman
           (Paleosuchus palpebrosus)
    • Authors: Christian Lind Malte; Jonas Bundgaard; Michael Schou Jensen; Mads Frost Bertelsen; Tobias Wang
      Abstract: Publication date: Available online 17 March 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Christian Lind Malte, Jonas Bundgaard, Michael Schou Jensen, Mads Frost Bertelsen, Tobias Wang
      Morphine and other opioids cause respiratory depression in high doses and lower the ventilatory responses to hypoxia and hypercapnia in mammals. Recent studies indicate that turtles respond similarly, but although they are used routinely for post-surgical analgesia, little is known about the physiological effects of opioids in reptiles. We therefore investigated the effects of morphine (10 and 20 mg kg−1) on gas exchange and ventilation in six dwarf caiman (Paleosuchus palpebrosus) using pneumotachography in a crossover design. Intraperitoneal injections of morphine changed the ventilation pattern from a typical intermittent/periodic pattern with a few or several breaths in ventilatory bouts to single breaths and prolonged the apnoea, such that respiratory frequency was depressed, whilst tidal volume was elevated. Furthermore, the duration of inspiration and especially expiration was prolonged. The resulting decrease in minute ventilation was attended by a lowering of the respiratory exchange ratio (RER) (especially for 20 mg kg−1 dose) indicating CO2 retention with a long time constant for approaching the new steady state. The changes in ventilation pattern and gas exchange reached a new stable level approximately 3 h after the morphine injection and did not significantly affect steady state O2 uptake, i.e. O2 consumption. As expected, the ventilatory response to 5% O2 was lower in morphine-treated caimans, but minute ventilation upon exposure to 2% CO2 did not differ significantly different from control animals.

      PubDate: 2018-03-19T06:59:32Z
      DOI: 10.1016/j.cbpa.2018.03.008
       
  • Untargeted metabolic profiling reveals distinct patterns of thermal
           sensitivity in two related notothenioids
    • Authors: Anja Rebelein; Hans-Otto Christian Bock
      Abstract: Publication date: Available online 27 December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anja Rebelein, Hans-Otto Pörtner, Christian Bock
      Antarctic marine ectothermal animals may be affected more than temperate species by rising temperatures due to ongoing climate change. Their specialisation on stable cold temperatures make them vulnerable to even small degrees of warming. Thus, addressing the impacts of warming on Antarctic organisms and identifying their potentially limited capacities to respond is of interest. The objective of the study was to determine changes in metabolite profiles related to temperature acclimation. In a long-term experiment adult fish of two Antarctic sister species Notothenia rossii and Notothenia coriiceps were acclimated to 0 °C and 5 °C for three months. Impacts and indicators of acclimation at the cellular level were determined from metabolite profiles quantified in gill tissue extracts using nuclear magnetic resonance (NMR) spectroscopy. Furthermore, the metabolite profiles of the two con-generic species were compared. NMR spectroscopy identified 37 metabolites that were present in each sample, but varied in their absolute concentration between species and between treatments. A decrease in amino acid levels indicated an increased amino acid catabolism after incubation to 5°C. In addition, long term warming initiated shifts in organic osmolyte concentrations and modified membrane structure observed by altered levels of phospholipid compounds. Differences in the metabolite profile between the two notothenioid species can be related to their divergent lifestyles, especially their different rates of motor activity. Increased levels of the Krebs cycle intermediate succinate and a higher reduction of amino acid concentrations in warm-acclimated N. rossii showed that N. rossii is more affected by warming than N. coriiceps.

      PubDate: 2018-01-03T22:36:05Z
       
  • Characterization of distinct ovarian isoform of crustacean female sex
           hormone in the kuruma prawn Marsupenaeus japonicus
    • Authors: Naoaki Tsutsui; Sayaka Kotaka; Tsuyoshi Ohira; Tatsuya Sakamoto
      Pages: 7 - 16
      Abstract: Publication date: March 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 217
      Author(s): Naoaki Tsutsui, Sayaka Kotaka, Tsuyoshi Ohira, Tatsuya Sakamoto
      The eyestalk hormone, crustacean female sex hormone (CFSH), regulates the development of female secondary sexual characteristics in the blue crab Callinectes sapidus. After its discovery, several CFSH gene orthologs have been identified in some species of the suborder Pleocyemata as well. Similarly, in species of another suborder (Dendrobranchiata), an ortholog (Maj-CFSH) has been characterized as an eyestalk factor expressed in both females and males of the kuruma prawn, Marsupenaeus japonicus. In this study, another novel CFSH isoform was identified in the same species using cDNA cloning, expression analysis, and recombinant protein production. The isoform has “CFSH-family” structural characteristics but is dominantly expressed in the ovary, and was therefore designated as Maj-CFSH-ov. Its mRNA and protein levels in vitellogenic ovaries are higher than those in non-vitellogenic ovaries. In the vitellogenic ovary, both mRNA and protein expression of Maj-CFSH-ov are localized to oogonia and previtellogenic oocytes that occupy a small portion of vitellogenic ovaries, but not to the major developing oocytes. A vitellogenesis-inhibiting peptide of M. japonicus (Pej-SGP-I) reduced the expression of vitellogenin in incubated ovarian fragments, but not that of Maj-CFSH-ov. These results indicate that M. japonicus possesses two CFSH isoforms that are derived from distinct tissues, the central X-organ/sinus gland complex and peripheral ovaries. The expression profile of Maj-CFSH-ov suggests its involvement in some reproductive process other than vitellogenesis.

      PubDate: 2017-12-24T20:26:42Z
      DOI: 10.1016/j.cbpa.2017.12.009
      Issue No: Vol. 217 (2017)
       
  • Different ecophysiological responses of freshwater fish to warming and
           acidification
    • Authors: Tiago F. Jesus; Inês C. Rosa; Tiago Repolho; Ana R. Lopes; Marta S. Pimentel; Vera M.F. Almeida-Val; Maria M. Coelho; Rui Rosa
      Pages: 34 - 41
      Abstract: Publication date: February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 216
      Author(s): Tiago F. Jesus, Inês C. Rosa, Tiago Repolho, Ana R. Lopes, Marta S. Pimentel, Vera M.F. Almeida-Val, Maria M. Coelho, Rui Rosa
      Future climate change scenarios predict threatening outcomes to biodiversity. Available empirical data concerning biological response of freshwater fish to climate change remains scarce. In this study, we investigated the physiological and biochemical responses of two Iberian freshwater fish species (Squalius carolitertii and the endangered S. torgalensis), inhabiting different climatic conditions, to projected future scenarios of warming (+3°C) and acidification (ΔpH=−0.4). Herein, metabolic enzyme activities of glycolytic (citrate synthase - CS, lactate dehydrogenase - LDH) and antioxidant (glutathione S-transferase, catalase and superoxide dismutase) pathways, as well as the heat shock response (HSR) and lipid peroxidation were determined. Our results show that, under current water pH, warming causes differential interspecific changes on LDH activity, increasing and decreasing its activity in S. carolitertii and in S. torgalensis, respectively. Furthermore, the synergistic effect of warming and acidification caused an increase in LDH activity of S. torgalensis, comparing with the warming condition. As for CS activity, acidification significantly decreased its activity in S. carolitertii whereas in S. torgalensis no significant effect was observed. These results suggest that S. carolitertii is more vulnerable to climate change, possibly as the result of its evolutionary acclimatization to milder climatic condition, while S. torgalensis evolved in the warmer Mediterranean climate. However, significant changes in HSR were observed under the combined warming and acidification (S. carolitertii) or under acidification (S. torgalensis). Our results underlie the importance of conducting experimental studies and address species endpoint responses under projected climate change scenarios to improve conservation strategies, and to safeguard endangered freshwater fish.

      PubDate: 2017-12-01T04:45:43Z
      DOI: 10.1016/j.cbpa.2017.11.007
      Issue No: Vol. 216 (2017)
       
  • Characterization of two channel catfish, Ictalurus punctatus,
           glucocorticoid receptors and expression following an acute stressor
    • Authors: Brian C. Small; Sylvie M.A. Quiniou
      Pages: 42 - 51
      Abstract: Publication date: February 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 216
      Author(s): Brian C. Small, Sylvie M.A. Quiniou
      Two channel catfish glucocorticoid receptor genes, ipGR1 (NR3C1_1) and ipGR2 (NR3C1_2) were partially characterized. Identification and analysis of the genomic organization of two channel catfish glucocorticoid (GC) receptors (GRs) revealed differences in the lengths of exons 1 and 2 and the addition of an extra 27-bp exon inserted after exon 2 in the GR1 gene, yielding a 9-aa insert in the receptor protein. Sequence of the 9-aa insert in ipGR1 (WRARQNTHG) is unique compared to other teleost fish GRs. Amino acid sequence alignment of the two channel catfish GRs, revealed 55% sequence identity between them, with a high degree of sequence conservation (82%) in the DNA binding and ligand binding domains. Real-time PCR indicated that ipGR1 and ipGR2 were expressed in all tissues evaluated. Channel catfish GR1 was predominantly expressed in the gills, nearly 25-fold higher than in the liver. GR1 expression was higher than GR2 expression in gills, intestine, head kidney and heart (P <0.05). Channel catfish hepatic GR1 mRNA expression was significantly (P<0.05) increased from pre-stress expression 30min following removal of the acute stressor. After 30min of stress and during the 2h recovery period, ipGR1 mRNA expression was higher relative to ipGR2 expression. Hepatic ipGR2 expression was not affected (P >0.05) by the acute stress event. The present study adds to the growing body of information on GR evolution and function and further demonstrates the unique regulation of the GC/GR system in teleost fish.

      PubDate: 2017-12-01T04:45:43Z
      DOI: 10.1016/j.cbpa.2017.11.011
      Issue No: Vol. 216 (2017)
       
  • The effects of temperature and food availability on growth, flexibility in
           metabolic rates and their relationships in juvenile common carp
    • Authors: Ling-Qing Zeng; Cheng Shi-Jian
      Abstract: Publication date: Available online 21 December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ling-Qing Zeng, Cheng Fu, Shi-Jian Fu
      Flexibility in phenotypic traits can allow organisms to handle environmental changes. However, the ecological consequences of flexibility in metabolic rates are poorly understood. Here, we investigated whether the links between growth and flexibility in metabolic rates vary between two temperatures. Common carp Cyprinus carpio were raised in three temperature treatments [the 18°C, 28°C and 28°C-food control (28°C-FC)] and fed to satiation of receiving food either once or twice daily for 4weeks. The morphology and metabolic rates (standard metabolic rate, SMR; maximum metabolic rate, MMR) were measured at the beginning and end of the experiment. The mean total food ingested by fish in the 28°C-FC treatment was the same as that by fish in the 18°C treatment at each food availability. The final SMR (not MMR and aerobic scope, AS=MMR-SMR) increased more in the 28°C and 28°C-FC treatments with twice-daily feedings than once–daily feedings. Fish in the 28°C treatment had a higher specific growth rate (SGR) than fish in the 28°C-FC and 18°C treatments at both food availabilities. However, no differences in feeding efficiency (FE) were found among the three treatments in fish fed twice daily. The flexibility in SMR was related to individual differences in SGR, not with food intake and FE; individuals who increased their SMR more had a smaller growth performance with twice-daily feedings at 28°C, but it did not exist at 18°C. Flexibility in SMR provides a growth advantage in juvenile common carp experiencing changes in food availability and this link is temperature-dependent.

      PubDate: 2017-12-24T20:26:42Z
       
  • Molecular characterization and gene expression of synaptosome-associated
           protein-25 (SNAP-25) in the brain during both seaward and homeward
           migrations of chum salmon Oncorhynchus keta
    • Authors: Takashi Abe; Yui Minowa Hideaki Kudo
      Abstract: Publication date: Available online 15 December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Takashi Abe, Yui Minowa, Hideaki Kudo
      It is generally accepted that information about some of the odorants in the natal streams of anadromous Pacific salmon (Genus Oncorhynchus) is imprinted during their seaward migration, and that anadromous Pacific salmon use olfaction to identify their natal streams during the homeward migration. However, little is known about the molecular mechanisms of the various pre-synaptic functions that are important for olfactory imprinting and memory retrieval in the salmon brain. Synaptosome-associated protein-25 (SNAP-25) mediates pre-synaptic vesicle exocytosis and regulates synaptic transmission and neuronal plasticity. Despite the importance of synaptic plasticity for memorization, the expression of SNAP-25 in the salmon brain is not well understood. In this study, snap25 expression was detected in chum salmon (O. keta) brains using molecular biological techniques. Two cDNAs encoding salmon SNAP-25 were isolated and sequenced (SNAP-25a and SNAP-25b). These cDNAs encoded proteins with 204 amino acid residues, which showed marked homology with each other (97%). The protein and nucleotide sequences demonstrated a high level of homology between salmon SNAP-25s and those of other teleost species. By quantitative PCR, the expression of snap25a and snap25b was detected in all regions of the salmon brain, especially in the telencephalon. The expression levels of snap25a in the olfactory blub were higher during seaward migration than in upriver and post-upriver migrations, reflecting synaptogenesis in the olfactory nervous system, and snap25b in the telencephalon was increased during upriver period. Our results indicated that snap25s gene is involved in synaptic plasticity for olfactory imprinting and/or olfactory memory retrieval in Pacific salmon.

      PubDate: 2017-12-24T20:26:42Z
       
  • Synthetic capacity does not predict elasmobranchs' ability to maintain
           trimethylamine oxide without a dietary contribution
    • Authors: Abigail Bockus; Brad Seibel
      Abstract: Publication date: Available online 15 December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Abigail B. Bockus, Brad A. Seibel
      Trimethylamine oxide (TMAO) is an organic osmolyte and universal protein stabilizer. Its role as a cytoprotectant is particularly important in ureosmotic elasmobranchs that accumulate high levels of urea, a macromolecular perturbant. Feeding is a key component in the turnover and maintenance of these nitrogenous compounds. However, previous studies examining TMAO regulation have been largely completed using starved individuals, when nitrogen balance is altered. Here, under fed conditions, we test the importance of dietary TMAO on long-term maintenance in three elasmobranch species with differing endogenous synthetic capacities. Smoothhounds (Mustelus canis), spiny dogfish (Squalus acanthias), and little skates (Leucoraja erinacea) exhibited species- and tissue-specific differences in their ability to conserve TMAO when fed a low TMAO diet for 56days. Smoothhounds, a species with the capacity for endogenous production, exhibited a decrease in muscle TMAO. Spiny dogfish and little skates, species with no reported ability for synthesis, exhibited decreases in plasma and liver TMAO, respectively. Our findings are contrary to previous starvation studies demonstrating constant levels of TMAO for up to 56days in elasmobranchs. Further, the previously reported synthetic capacity of these species did not correlate with their ability to conserve TMAO and cannot be used to predict a species reliance on dietary contributions for prolonged maintenance. It is possible that all species rely to a degree on absorption of TMAO from the diet or that alternate synthetic or regulatory pathways play a larger role than previously thought.

      PubDate: 2017-12-24T20:26:42Z
       
  • Clown knifefish (Chitala ornata) oxygen uptake and its partitioning in
           present and future temperature environments
    • Authors: Dang Diem; Tuong Tran Bao Ngoc Thi Nhu Huynh Thi
      Abstract: Publication date: Available online 6 December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Dang Diem Tuong, Tran Bao Ngoc, Vo Thi Nhu Huynh, Do Thi Thanh Huong, Nguyen Thanh Phuong, Tran Ngoc Hai, Tobias Wang, Mark Bayley
      It has been argued that tropical ectotherms are more vulnerable to the projected temperature increases than their temperate relatives, because they already live closer to their upper temperature limit. Here we examine the effects of a temperature increase in environmental temperature to 6°C above the present day median temperature (27°C) in the freshwater air-breathing fish Chitala ornata, on aspects of its respiratory physiology in both normoxia and in hypoxia. We found no evidence of respiratory impairment with elevated temperature. The standard metabolic rate (SMR) and routine metabolic rate (RMR) in the two temperatures in normoxia and hypoxia increased with Q10 values between 2.3 and 2.9, while the specific dynamic action (SDA) and its coefficient increased from 7.8 to 14.7% in 27°C and 33°C, respectively. In addition, Chitala ornata exhibited significantly improved growth at the elevated temperature in both hypoxic and normoxic water. While projected temperature increases may negatively impact other essential aspects in this animal's environment, we see no evidence of a negative impact on this species itself.

      PubDate: 2017-12-12T06:32:13Z
       
  • Individuals exhibit consistent differences in their metabolic rates across
           changing thermal conditions
    • Authors: Sonya Auer; Karine Salin Graeme Anderson Neil Metcalfe
      Abstract: Publication date: Available online 6 December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sonya K. Auer, Karine Salin, Graeme J. Anderson, Neil B. Metcalfe
      Metabolic rate has been linked to growth, reproduction, and survival at the individual level and is thought to have far reaching consequences for the ecology and evolution of organisms. However, differences in metabolic rate among individuals must be consistent (i.e. repeatable) over at least some portion of their lifetime in order to predict their longer-term effects on population dynamics and how they will respond to selection. Previous studies demonstrate that metabolic rates are repeatable under constant conditions but potentially less so in more variable environments. We measured the standard (= minimum) metabolic rate, maximum metabolic rate, and aerobic scope (= interval between standard and maximum rates) in juvenile brown trout (Salmo trutta) after 5weeks acclimation to each of three consecutive test temperatures (10, 13, and then 16°C) that simulated the warming conditions experienced throughout their first summer of growth. We found that metabolic rates are repeatable over a period of months under changing thermal conditions: individual trout exhibited consistent differences in all three metabolic traits across increasing temperatures. Initial among-individual differences in metabolism are thus likely to have significant consequences for fitness-related traits over key periods of their life history.

      PubDate: 2017-12-12T06:32:13Z
       
  • The effect of cold acclimation on active ion transport in cricket
           ionoregulatory tissues
    • Authors: Lauren Des; Marteaux Soheila Khazraeenia Gil Yerushalmi Andrew Donini Natalia
      Abstract: Publication date: Available online 13 November 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lauren E. Des Marteaux, Soheila Khazraeenia, Gil Y. Yerushalmi, Andrew Donini, Natalia G. Li, Brent J. Sinclair
      Cold-acclimated insects defend ion and water transport function during cold exposure. We hypothesized that this is achieved via enhanced active transport. The Malpighian tubules and rectum are likely targets for such transport modifications, and recent transcriptomic studies indicate shifts in Na+-K+ ATPase (NKA) and V-ATPase expression in these tissues following cold acclimation. Here we quantify the effect of cold acclimation (one week at 12°C) on active transport in the ionoregulatory organs of adult Gryllus pennsylvanicus field crickets. We compared primary urine production of warm- and cold-acclimated crickets in excised Malpighian tubules via Ramsay assay at a range of temperatures between 4 and 25°C. We then compared NKA and V-ATPase activities in Malpighian tubule and rectal homogenates from warm- and cold-acclimated crickets via NADH-linked photometric assays. Malpighian tubules of cold-acclimated crickets excreted fluid at lower rates at all temperatures compared to warm-acclimated crickets. This reduction in Malpighian tubule excretion rates may be attributed to increased NKA activity that we observed for cold-acclimated crickets, but V-ATPase activity was unchanged. Cold acclimation had no effect on rectal NKA activity at either 21°C or 6°C, and did not modify rectal V-ATPase activity. Our results suggest that an overall reduction, rather than enhancement of active transport in the Malpighian tubules allows crickets to maintain hemolymph water balance during cold exposure, and increased Malpighian tubule NKA activity may help to defend and/or re-establish ion homeostasis.

      PubDate: 2017-11-20T03:19:08Z
       
  • Methemoglobin reductase activity in intact fish red blood cells
    • Authors: Frank Jensen; Karsten Nielsen
      Abstract: Publication date: Available online 10 November 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Frank B. Jensen, Karsten Nielsen
      Red blood cells (RBCs) possess methemoglobin reductase activity that counters the ongoing oxidation of hemoglobin (Hb) to methemoglobin (metHb), which in circulating blood is caused by Hb autoxidation or reactions with nitrite. We describe an assay for determining metHb reductase activity in intact RBCs in physiological saline at normal Pco2 and pH. After initial loading of oxygenated RBCs with nitrite (partly oxidizing Hb to metHb), the nitrite is removed by three washes of the RBCs in nitrite-free physiological saline to enable the detection of RBC metHb reductase activity in the absence of counteracting oxidation. This assay was used to compare metHb reduction in rainbow trout and carp RBCs under both oxygenated and deoxygenated conditions. Washing resulted in effective wash-out of nitrite to low and safe values (~ 2μM). The subsequent decline in [metHb] with time followed first-order kinetics, allowing characterization of metHb reductase activity through the first order rate constant k. In oxygenated RBCs at 25°C, the k values for rainbow trout and carp were slightly below or above 0.01min−1, respectively; which is double the value reported for mammals at 37°C. We conclude the higher metHb reductase activity in fish offsets their higher Hb autoxidation and higher likelihood of encountering elevated nitrite. Deoxygenation significantly raised the rates of RBC metHb reduction, and more so in rainbow trout than in carp. The temperature sensitivity of metHb reduction in rainbow trout RBCs was high (Q10 ~ 2.8) and instrumental in handling increased Hb autoxidation with temperature.

      PubDate: 2017-11-11T21:34:25Z
       
  • Respiration-based monitoring of metabolic rate following cold-exposure in
           two invasive Anoplophora species depending on acclimation regime
    • Authors: Javal Roques; Roux Laparie
      Abstract: Publication date: Available online 10 November 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): M. Javal, A. Roques, G. Roux, M. Laparie
      The Asian andCitrus longhorned beetles, Anoplophora glabripennis (ALB) and A. chinensis (CLB) respectively, are two closely related invasive species with overlapping native ranges. Although both species have rather similar biological characteristics, they differ in their invasion patterns. ALB shows numerous, but local, outbreaks in urban areas of North-East America, Western andCentral Europe, whereas CLB has colonized a large part of Northern Italy. Temperature is pivotal in setting distribution limits of ectotherms. Low temperature may be limiting for larvae since they are the main overwintering stage for both species. To investigate whether differential cold tolerance may contribute to setting the respective limits of the range invaded by each species, we monitored larval metabolic rate before and after exposure to a one-week ecologically relevant moderate cold stress (−2/+2°C, 14/10h). We tested two distinctive fluctuating regimes before the cold exposure to check whether larval acclimation significantly altered their cold tolerance. Survival was high in all conditions for both species. Visual examination showed temporary locomotor inactivity during the stress but respiration rates were not altered after the stress suggesting that larvae could rapidly resume their initial metabolic activity. The respiration rate was globally higher in ALB than in CLB. Together, these results tend to indicate that both species have similar tolerance to the moderate cold stress tested, but also that ALB may be better at maintaining metabolic activity at cold than CLB. These observed differences could affect phenology in both species and in turn their establishment potential.

      PubDate: 2017-11-11T21:34:25Z
       
  • Functional redundancy of glucose acquisition mechanisms in the hindgut of
           Pacific hagfish (Eptatretus stoutii)
    • Authors: Alyssa Weinrauch; Alexander Clifford Greg Goss
      Abstract: Publication date: Available online 7 November 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Alyssa M. Weinrauch, Alexander M. Clifford, Greg G. Goss
      This study examined the mechanisms of glucose acquisition in the hindgut of Pacific hagfish (Eptatretus stoutii) using in vitro gut sac techniques. The intestine was determined to have the capacity to digest maltose into glucose along the entirety of the tract, including the foregut. Glucose uptake was biphasic and consisted of a high-affinity, low-capacity concentration-dependent component conforming to Michaelis-Menten kinetics (Km 0.37mM, Jmax 8.48nmol/cm2/h) as well as a diffusive component. There was no observed difference in glucose flux rate along the length of the intestine, similar to other nutrients investigated in the hagfish intestine. A reduced sodium (<1mM) environment did not result in a change in glucose uptake rates, likely due to a functional redundancy of glucose transporters. There was no observed effect of phloretin, yet the sodium glucose-linked transporter (SGLT)-specific inhibitor phlorizin significantly reduced glucose uptake at all concentrations tested (0.0001–1mM). Additionally, the glucose transporter (GLUT) inhibitor cytochalasin b significantly reduced glucose transport rates. The effects of these pharmacological inhibition experiments suggest the presence of multiple types of glucose transport proteins. This study clarifies the uptake strategies used by hagfish to acquire glucose at the intestine and provides insight into the evolution of such transport systems in early-diverging vertebrates.

      PubDate: 2017-11-11T21:34:25Z
       
  • Dietary antioxidants, food deprivation and growth affect differently
           oxidative status of blood and brain in juvenile European seabass
           (Dicentrarchus labrax)
    • Authors: David Costantini; Dario Angeletti Claudia Strinati Pamela Trisolino Alessandro Carlini
      Abstract: Publication date: Available online 4 November 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): David Costantini, Dario Angeletti, Claudia Strinati, Pamela Trisolino, Alessandro Carlini, Giuseppe Nascetti, Claudio Carere
      Compensatory growth may increase molecular oxidative damage, which may be mitigated through the intake of dietary antioxidants. However, dietary antioxidants may also reduce concentration of antioxidant enzymes, which have a key role in regulating the oxidative status. Here we investigated whether feeding on a diet rich in antioxidants (vitamin E) enables juvenile European seabass (Dicentrarchus labrax) to catch up after a period of food deprivation with negligible effects on the oxidative stress to blood and brain as compared to fish feeding on a normal diet (i.e., not enriched in antioxidants). The results show that a higher intake in antioxidants favoured compensatory growth, but this came at a cost in terms of increased oxidative damage. Increased intake of antioxidants also resulted in changes in the activity concentration of enzymatic antioxidant defences and increased protein oxidative damage in both brain and blood. In addition, food deprivation caused increased protein oxidative damage in brain. Our findings show that the beneficial effects of dietary antioxidants on growth may be offset by hidden detrimental effects and that different early life events affect different components of oxidative status of a given tissue.

      PubDate: 2017-11-04T19:45:21Z
       
  • The hatching process and mechanisms of adaptive hatching acceleration in
           hourglass treefrogs, Dendropsophus ebraccatus
    • Authors: Kristina Cohen; Michael Piacentino Karen Warkentin
      Abstract: Publication date: Available online 19 October 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kristina L. Cohen, Michael L. Piacentino, Karen M. Warkentin
      Environmentally cued hatching is well documented in anurans, enabling embryos to escape diverse threats. However, knowledge of anuran hatching mechanisms is limited and based largely on aquatic-breeding species without known plasticity in hatching timing. Generally, hatching gland cells produce a hatching enzyme that degrades the vitelline membrane. We investigated hatching and its regulation in terrestrial embryos of hourglass treefrogs, Dendropsophus ebraccatus, which accelerate hatching to escape dehydration. We specifically tested if changes in hatching gland cell development or hatching enzyme gene expression are associated with accelerated hatching. We measured perivitelline chamber size of well-hydrated eggs over development as an indicator of breakdown of the vitelline membrane and found that the size of the perivitelline chamber increased steadily until hatching, suggesting gradual hatching enzyme release and vitelline membrane degradation. Hatching gland cells peaked in abundance and began regression substantially prior to hatching, but we found no developmental differences in the abundance or surface area of hatching gland cells between dry and well-hydrated embryos. Hatching enzyme gene expression also peaked early in development then declined, with no difference between hydration treatments. In D. ebraccatus breakdown of the vitelline membrane appears gradual, mediated by hatching enzyme release starting long before hatching. However, hatching acceleration is not associated with ontogenetic changes in hatching gland cell development or hatching enzyme gene expression. This hatching process contrasts with that of red-eyed treefrogs, Agalychnis callidryas, which appear to release enzyme acutely at hatching, yet both species are capable of hatching to escape acute threats.

      PubDate: 2017-11-04T19:45:21Z
       
 
 
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