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  Subjects -> BIOLOGY (Total: 3026 journals)
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BIOCHEMISTRY (239 journals)                  1 2 | Last

Showing 1 - 200 of 239 Journals sorted alphabetically
AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 2)
ACS Central Science     Open Access   (Followers: 8)
ACS Chemical Biology     Full-text available via subscription   (Followers: 270)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 18)
Acta Biochimica Polonica     Open Access  
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 9)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 8)
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: 9)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 2)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
American Journal of Biochemistry     Open Access   (Followers: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 66)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 15)
American Journal of Polymer Science     Open Access   (Followers: 26)
Amino Acids     Hybrid Journal   (Followers: 8)
Analytical and Bioanalytical Chemistry Research     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 164)
Angiogenesis     Hybrid Journal   (Followers: 3)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 55)
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: 7)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 20)
Archives of Insect Biochemistry and Physiology     Hybrid Journal  
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
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: 22)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 4)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 15)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 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: 326)
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: 14)
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: 9)
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)
Biofuels     Hybrid Journal   (Followers: 11)
Biogeochemistry     Hybrid Journal   (Followers: 14)
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: 22)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
Bit├ícora 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: 6)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
ChemBioChem     Hybrid Journal   (Followers: 7)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 20)
Chemical Engineering Journal     Hybrid Journal   (Followers: 46)
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: 6)
Chemistry & Biology     Full-text available via subscription   (Followers: 30)
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: 68)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 61)
Clinical Lipidology     Full-text available via subscription   (Followers: 1)
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
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: 7)
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 Chemical Biology     Hybrid Journal   (Followers: 2)
Current Medicinal Chemistry     Hybrid Journal   (Followers: 15)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 29)
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: 57)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Food & Function     Full-text available via subscription   (Followers: 6)
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: 16)
Green Chemistry     Full-text available via subscription   (Followers: 10)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 5)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 3)
Indian Journal of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Indonesian Biomedical Journal     Open Access  
Insect Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3)
International Journal of Biochemistry & Cell Biology     Hybrid Journal   (Followers: 7)
International Journal of Biochemistry and Biophysics     Open Access   (Followers: 1)
International Journal of Biological Chemistry     Open Access   (Followers: 4)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 6)
International Journal of Food Contamination     Open Access  
International Journal of Plant Physiology and Biochemistry     Open Access   (Followers: 1)
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: 42)
Journal of Biochemistry and Molecular Biology Research     Open Access  
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 208)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 7)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Chemical Biology     Hybrid Journal   (Followers: 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: 4)
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  
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 5)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 7)
Journal of Medical and Biomedical Sciences     Open Access  
Journal of Medical Biochemistry     Open Access   (Followers: 4)
Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
Journal of Molecular Biochemistry     Open Access   (Followers: 3)
Journal of Molecular Diagnostics     Hybrid Journal   (Followers: 6)
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: 22)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 1)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 7)
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: 8)
Methods in Enzymology     Full-text available via subscription   (Followers: 11)
Molecular and Biochemical Parasitology     Hybrid Journal   (Followers: 2)
Molecular and Cellular Biochemistry     Hybrid Journal   (Followers: 6)
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: 73)
Nature Communications     Open Access   (Followers: 210)
Neurosignals     Open Access  
New Comprehensive Biochemistry     Full-text available via subscription  
NOVA     Open Access  
Novelty in Biomedicine     Open Access  
OA Biochemistry     Open Access   (Followers: 1)

        1 2 | Last

Journal Cover Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [SJR: 0.939]   [H-I: 84]   [4 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [3118 journals]
  • 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
    • 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
       
  • Untargeted metabolic profiling reveals distinct patterns of thermal
           sensitivity in two related notothenioids
    • 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
    • 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
       
  • The effects of temperature and food availability on growth, flexibility in
           metabolic rates and their relationships in juvenile common carp
    • 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
    • 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
    • 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
    • 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
    • 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
       
  • Different ecophysiological responses of freshwater fish to warming and
           acidification
    • 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
       
  • Characterization of two channel catfish, Ictalurus punctatus,
           glucocorticoid receptors and expression following an acute stressor
    • 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
       
  • In Appreciation
    • Abstract: Publication date: January 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 215


      PubDate: 2017-11-20T03:19:08Z
       
  • The effect of cold acclimation on active ion transport in cricket
           ionoregulatory tissues
    • 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
    • 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
    • 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)
    • 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
       
  • Ontogeny of skeletal and cardiac muscle mitochondria oxygen fluxes in two
           breeds of chicken
    • Abstract: Publication date: January 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 215
      Author(s): Sarah K.G. Sirsat, Edward M. Dzialowski
      From its earliest days of domestication, the domestic chicken (Gallus gallus domesticus) has been selectively bred for specific traits. Decades of genetic selection have resulted in significant dissimilarities in metabolism and growth between breeds, in particular fast-growing broilers and highly productive layers. A chicken develops the capacity to elevate metabolism in response to decreases in ambient temperature upon hatching, including well-developed methods of regulating thermogenesis. However, a differential timing between incipient endothermic capacities of broiler and layer strains exists. Although both broiler and layer chicks show the hallmark rapid attainment of endothermic capacity of precocial birds, endothermic capacity of broilers matures faster than that of layers. Here we characterized changes in morphology and mitochondria physiology during the developmental transition as the animals become endothermic. Changes in body mass occurred at a faster rate in broilers, with hatching embryos showing significant increases over embryonic body mass, while layers did not exhibit significant differences in mass until after hatch. Heart and liver both exhibited rapid growth upon hatching that occurred with little change in body mass in both breeds. Skeletal and cardiac mitochondrial respiration capacity in broilers increased from the embryonic stage through hatching. Oxidative phosphorylation was more tightly coupled to ATP production in broilers than layer muscles during external pipping. By selecting for faster growth and higher meat yield, the physiological transition from ectothermy to endothermy was also affected: differences in whole-animal, tissue, and organelle responses are evident in these two divergent breeds of chicken.

      PubDate: 2017-11-04T19:45:21Z
       
  • Nutritional physiology of mahi-mahi (Coryphaena hippurus): Postprandial
           metabolic response to different diets and metabolic impacts on swim
           performance
    • Abstract: Publication date: January 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 215
      Author(s): John D. Stieglitz, Daniel D. Benetti, Martin Grosell
      Migratory pelagic fish species, such as the mahi-mahi (Coryphaena hippurus), must balance numerous metabolic demands simultaneously in order to survive in a challenging oceanic environment. Energetic support for such demands comes from a variety of natural prey items in the wild and can come from manufactured pelletized feed in captivity. This study quantified postprandial metabolism, commonly referred to as specific dynamic action (SDA), over time in adult mahi-mahi (706±25g; 38±0.7cm FL) in response to satiation feeding using three different natural and manufactured diets. Results indicate that during satiation feeding the amount of food ingested is dictated by energy content rather than prey mass, regardless of moisture content of the diet. Ingested meal energy did not differ significantly across groups (473±45kJ), nor did the duration of SDA (36±2.1h). Satiation feeding levels ranged from 2.9–16.2% bodyweight depending on the diet. Peak SDA and SDA magnitude were both significantly decreased in response to dry pelletized diet compared to the natural forage diets, despite equivalent energy consumption. Swim performance and maximum metabolic rate were not impacted significantly in satiation fed fish compared to unfed fish, supporting the evidence that mahi-mahi are able to maintain multiple metabolic demands at one time without compromising performance.

      PubDate: 2017-11-04T19:45:21Z
       
  • Unraveling vasotocinergic, isotocinergic and stress pathways after food
           deprivation and high stocking density in the gilthead sea bream
    • Abstract: Publication date: January 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 215
      Author(s): Arleta Krystyna Skrzynska, Juan Antonio Martos-Sitcha, Gonzalo Martínez-Rodríguez, Juan Miguel Mancera
      The influence of chronic stress, induced by food deprivation (FD) and/or high stocking density (HSD), was assessed on stress, vasotocinergic and isotocinergic pathways of the gilthead sea bream (Sparus aurata). Fish were randomly assigned to one of the following treatments: (1) fed at low stocking density (LSD-F; 5kg·m−3); (2) fed at high stocking density (HSD-F, 40kg·m−3); (3) food-deprived at LSD (LSD-FD); and (4) food-deprived at HSD (HSD-FD). After 21days, samples from plasma, liver, hypothalamus, pituitary and head-kidney were collected. Both stressors (FD and HSD) induced a chronic stress situation, as indicated by the elevated cortisol levels, the enhancement in corticotrophin releasing hormone (crh) expression and the down-regulation in corticotrophin releasing hormone binding protein (crhbp) expression. Changes in plasma and liver metabolites confirmed a metabolic adjustment to cope with energy demand imposed by stressors. Changes in avt and it gene expression, as well as in their specific receptors (avtrv1a, avtrv2 and itr) at central (hypothalamus and pituitary) and peripheral (liver and head-kidney) levels, showed that vasotocinergic and isotocinergic pathways are involved in physiological changes induced by FD or HSD, suggesting that different stressors are handled through different stress pathways in S. aurata.

      PubDate: 2017-11-04T19:45:21Z
       
  • Effect of combined stress (salinity and temperature) in European sea bass
           Dicentrarchus labrax osmoregulatory processes
    • Abstract: Publication date: January 2018
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 215
      Author(s): Waliullah Masroor, Emilie Farcy, Romain Gros, Catherine Lorin-Nebel
      European sea bass Dicentrarchus labrax undertake seasonal migrations to estuaries and lagoons that are characterized by fluctuations in environmental conditions. Their ability to cope with these unstable habitats is undeniable, but it is still not clear how and to what extent salinity acclimation mechanisms are affected at temperatures higher than in the sea. In this study, juvenile sea bass were pre-acclimated to seawater (SW) at 18°C (temperate) or 24°C (warm) for 2weeks and then transferred to fresh water (FW) or SW at the respective temperature. Transfer to FW for two weeks resulted in decreased blood osmolalities and plasma Cl− at both temperatures. In FW warm conditions, plasma Na+ was ~15% lower and Cl− was ~32% higher than in the temperate-water group. Branchial Na+/K+-ATPase (NKA) activity measured at the acclimation temperature (Vapparent) did not change according to the conditions. Branchial Na+/K+-ATPase activity measured at 37°C (Vmax) was lower in warm conditions and increased in FW compared to SW conditions whatever the considered temperature. Mitochondrion-rich cell (MRC) density increased in FW, notably due to the appearance of lamellar MRCs, but this increase was less pronounced in warm conditions where MRC's size was lower. In SW warm conditions, pavement cell apical microridges are less developed than in other conditions. Overall gill morphometrical parameters (filament thickness, lamellar length and width) differ between fish that have been pre-acclimated to different temperatures. This study shows that a thermal change affects gill plasticity affecting whole-organism ion balance two weeks after salinity transfer.

      PubDate: 2017-11-04T19:45:21Z
       
  • Dietary antioxidants, food deprivation and growth affect differently
           oxidative status of blood and brain in juvenile European seabass
           (Dicentrarchus labrax)
    • 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
    • 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
       
  • High amylose starch consumption induces obesity in Drosophila melanogaster
           and metformin partially prevents accumulation of storage lipids and
           shortens lifespan of the insects
    • Abstract: Publication date: Available online 18 October 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Oleksandra B. Abrat, Janet M. Storey, Kenneth B. Storey, Volodymyr I. Lushchak
      There are very few studies that have directly analyzed the effects of dietary intake of slowly digestible starches on metabolic parameters of animals. The present study examined the effects of slowly digestible starch with high amylose content (referred also as amylose starch) either alone, or in combination with metformin on the development, lifespan, and levels of glucose and storage lipids in the fruit fly Drosophila melanogaster. Consumption of amylose starch in concentrations 0.25–10% did not affect D. melanogaster development, whereas 20% starch delayed pupation and reduced the number of larvae that reached the pupal stage. Starch levels in larval food, but not in adult food, determined levels of triacylglycerides in eight-day-old adult flies. Rearing on diet with 20% starch led to shorter lifespan and a higher content of triacylglycerides in the bodies of adult flies as compared with the same parameters in flies fed on 4% starch diet. Food supplementation with 10mM metformin partly attenuated the negative effects of high starch concentrations on larval pupation and decreased triacylglyceride levels in adult flies fed on 20% starch. Long-term consumption of diets supplemented with metformin and starch decreased lifespan of the insects, compared with the diet supplemented with starch only. The data show that in Drosophila high starch consumption may induce a fat fly phenotype and metformin may partially prevent it.

      PubDate: 2017-11-04T19:45:21Z
       
  • How important is the CO2 chemoreflex for the control of breathing'
           Environmental and evolutionary considerations
    • Abstract: Publication date: Available online 29 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Joseph M. Santin
      Haldane and Priestley (1905) discovered that the ventilatory control system is highly sensitive to CO2. This “CO2 chemoreflex” has been interpreted to dominate control of resting arterial PCO2/pH (PaCO2/pHa) by monitoring PaCO2/pHa and altering ventilation through negative feedback. However, PaCO2/pHa varies little in mammals as ventilation tightly couples to metabolic demands, which may minimize chemoreflex control of PaCO2. The purpose of this synthesis is to (1) interpret data from experimental models with meager CO2 chemoreflexes to infer their role in ventilatory control of steady-state PaCO2, and (2) identify physiological causes of respiratory acidosis occurring normally across vertebrate classes. Interestingly, multiple rodent and amphibian models with minimal/absent CO2 chemoreflexes exhibit normal ventilation, gas exchange, and PaCO2/pHa. The chemoreflex, therefore, plays at most a minor role in ventilatory control at rest; however, the chemoreflex may be critical for recovering PaCO2 following acute respiratory acidosis induced by breath-holding and activity in many ectothermic vertebrates. An apparently small role for CO2 feedback in the genesis of normal breathing contradicts the prevailing view that central CO2/pH chemoreceptors increased in importance throughout vertebrate evolution. Since the CO2 chemoreflex contributes minimally to resting ventilation, these CO2 chemoreceptors may have instead decreased importance throughout tetrapod evolution, particularly with the onset and refinement of neural innovations that improved the matching of ventilation to tissue metabolic demands. This distinct and elusive “metabolic ventilatory drive” likely underlies steady-state PaCO2 in air-breathers. Uncovering the mechanisms and evolution of the metabolic ventilatory drive presents a challenge to clinically-oriented and comparative respiratory physiologists alike.

      PubDate: 2017-09-29T22:28:41Z
       
  • Effects of exercise training on excitation-contraction coupling, calcium
           dynamics and protein expression in the heart of the Neotropical fish
           Brycon amazonicus
    • Abstract: Publication date: Available online 29 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Rafael Zanelli Rissoli, Eliton da Silva Vasconcelos, Francisco Tadeu Rantin, Ana Lúcia Kalinin
      Matrinxã (Brycon amazonicus) is a great swimming performance teleost fish from the Amazon basin. However, the possible cardiac adaptations of this ability are still unknown. Therefore, the aim of the present work was to investigate the effects of prolonged exercise (EX group - 60days under 0.4BL·s−1) on ventricular contractility by (i) in-vitro analysis of contractility comparing the relative roles of sodium/calcium exchanger (NCX) and sarcoplasmic reticulum (SR) in the excitation-contraction (E-C) coupling and (ii) molecular analysis of NCX, sarcoplasmic reticulum Ca2+ ATPase (SERCA2) and phospholamban (PLB) expression and quantification. The exercise training significantly improved twitch tension, cardiac pumping capacity and the contraction rate when compared to controls (CT). Inhibition of the NCX function, replacing Na+ by Li+ in the physiological solutions, diminished cardiac contractility in the EX group, reduced all analyzed parameters under both high and low stimulation frequencies. The SR blockage, using 10μM ryanodine, caused ~50% tension reduction in CT at most analyzed frequencies while in EX, reductions (34–54%) were only found at higher frequencies. SR inhibition also decreased contraction and relaxation rates in both groups. Additionally, higher post-rest contraction values were recorded for EX, indicating an increase in SR Ca2+ loading. Higher NCX and PLB expression rates and lower SERCA2 rates were found in EX. Our data indicate that matrinxã presents a modulation in E-C coupling after exercise-training, enhancing the SR function under higher frequencies. This was the first study to functionally analyze the effects of swimming-induced exercise on fish cardiac E-C coupling.

      PubDate: 2017-09-29T22:28:41Z
       
  • Feeding alters blood flow patterns in the American alligator (Alligator
           mississippiensis)
    • Abstract: Publication date: Available online 27 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anders Findsen, I.I. Dane Crossley, Tobias Wang
      The crocodilian cardiovascular design with a four-chambered heart and a left aorta that emerge from the right ventricle allows blood to be shunted away from the lungs, a right-to-left (R-L) shunt. The adaptive significance of this R-L shunt remains both poorly understood and controversial with particular debate on its putative role during digestion. Here we measure blood flow patterns in the right aorta (RAo), left aorta (LAo) and the coeliac artery (CoA) of undisturbed American alligators (Alligator mississippiensis) during fasting and throughout most of the digestive period. Digestion doubled blood flow in the RAo (10.1±0.9 to 20.7±1.5ml min−1 kg−1), whereas LAo increased approximately 3-fold (3.8±0.6 to 12.2±2.1ml min−1 kg−1). Blood flow in the CoA increased more than four-fold during digestion (3.0±0.6 to 13.3±1.6ml min−1 kg−1). The rise in blood flows was achieved by a doubling of heart rate (18.5±3.3 to 37.8±3.6ml min−1 kg−1). Maximal flows measured in all arteries and heart rate occurred in the first hour of the postprandial period and continued for the next seven hours.

      PubDate: 2017-09-29T22:28:41Z
       
  • Differential expression of putative sodium-dependent cation-chloride
           cotransporters in Aedes aegypti
    • Abstract: Publication date: December 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 214
      Author(s): Peter M. Piermarini, Daniel C. Akuma, John C. Crow, Taylor L. Jamil, Willa G. Kerkhoff, Kenyatta C.M.F. Viel, Christopher M. Gillen
      The yellow fever mosquito, Aedes aegypti, has three genes that code for proteins with sequence similarity to vertebrate Na+-K+-Cl− cotransporters (NKCCs) of the solute-linked carrier 12 superfamily of cation-chloride cotransporters (CCCs). We hypothesized that these mosquito NKCC orthologues have diverged to perform distinct roles in salt secretion and absorption. In phylogenetic analyses, one protein (aeNKCC1) groups with a Drosophila melanogaster NKCC that mediates salt secretion whereas two others (aeCCC2 and aeCCC3) group with a Drosophila transporter that is not functionally characterized. The aeCCC2 and aeCCC3 genes probably result from a tandem gene duplication in the mosquito lineage; they have similar exon structures and are consecutive in genomic DNA. Predicted aeCCC2 and aeCCC3 proteins differ from aeNKCC1 and vertebrate NKCCs in residues from the third transmembrane domain known to influence ion and inhibitor binding. Quantitative PCR revealed that aeNKCC1 and aeCCC2 were approximately equally expressed in larvae and adults, whereas aeCCC3 was approximately 100-fold more abundant in larvae than in adults. In larval tissues, aeCCC2 was approximately 2-fold more abundant in Malpighian tubules compared to anal papillae. In contrast, aeCCC3 was nearly 100-fold more abundant in larval anal papillae compared to Malpighian tubules, suggesting a role in absorption. Western blots with polyclonal antibodies against isoform-specific peptides revealed stronger aeCCC2 immunoreactivity in adults versus larvae, whereas aeCCC3 immunoreactivity was stronger in larvae versus adults. The differential expression pattern of aeCCC2 and aeCCC3, and their sequence divergence in transmembrane domains, suggests that they may have different roles in transepithelial salt transport.

      PubDate: 2017-09-23T20:20:07Z
       
  • Interrelationship of salinity shift with oxidative stress and lipid
           metabolism in the monogonont rotifer Brachionus koreanus
    • Abstract: Publication date: Available online 23 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Min-Chul Lee, Jun Chul Park, Duck-Hyun Kim, Sujin Kang, Kyung-Hoon Shin, Heum Gi Park, Jeonghoon Han, Jae-Seong Lee
      Salinity is a critical key abiotic factor affecting biological processes such as lipid metabolism, yet the relationship between salinity and lipid metabolism has not been studied in the rotifer. To understand the effects of salinity on the monogonont rotifer B. koreanus, we examined high saline (25 and 35psu) conditions compared to the control (15psu). In vivo life cycle parameters (e.g. cumulative offspring and life span) were observed in response to 25 and 35psu compared to 15psu. In addition, to investigate whether high salinity induces oxidative stress, the level of reactive oxygen species (ROS) and glutathione S-transferase activity (GST) were measured in a salinity- (15, 25, and 35psu; 24h) and time-dependent manner (3, 6, 12, 24h; 35psu). Furthermore composition of fatty acid (FA) and lipid metabolism-related genes (e.g. elongases and desaturases) were examined in response to different salinity conditions. As a result, retardation in cumulative offspring and significant increase in life span were demonstrated in the 35psu treatment group compared to the control (15psu). Furthermore, ROS level and GST activity have both demonstrated a significant increase (P <0.05) in the 35psu treatment. In general, the quantity of FA and mRNA expression of the lipid metabolism-related genes was significantly decreased (P <0.05) in response to high saline condition with exceptions for both GST-S4 and S5 demonstrated a significant increase in their mRNA expression. This study demonstrates that high salinity induces oxidative stress, leading to a negative impact on lipid metabolism in the monogonont rotifer, B. koreanus.

      PubDate: 2017-09-23T20:20:07Z
       
  • Purinergic and adenosine receptors contribute to hypoxic hyperventilation
           in zebrafish (Danio rerio)
    • Abstract: Publication date: Available online 21 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Alisha J. Coe, Alexina J. Picard, Michael G. Jonz
      The chemoreceptors involved in oxygen sensing in teleost fish are neuroepithelial cells (NECs) in the gills, and are analogous to glomus cells in the mammalian carotid body. Purinergic signalling mechanisms involving the neurotransmitters, ATP and adenosine, have been identified in mediating hypoxic signalling in the carotid body, but these pathways are not well understood in the fish gill. The present study used a behavioural assay to screen for the effects of drugs, that target purinergic and adenosine receptors, on the hyperventilatory response to hypoxia in larval zebrafish (Danio rerio) in order to determine if the receptors on which these drugs act may be involved in hypoxic signalling. The purinergic receptor antagonist, PPADS, targets purinergic P2X2/3 receptors and inhibited the hyperventilatory response to hypoxia (IC50 =18.9μM). The broad-spectrum purinergic agonist, ATPγS, elicited a hyperventilatory response (EC50 =168μM). The non-specific adenosine receptor antagonist, caffeine, inhibited the hyperventilatory response to hypoxia, as did the specific A2a receptor antagonist, SCH58261 (IC50 =220nM). These results suggest that P2X2/3 and A2a receptors are candidates for mediating hypoxic hyperventilation in zebrafish. This study highlights the potential of applying chemical screening to ventilatory behaviour in zebrafish to further our understanding of the pathways involved in signalling by gill NECs and oxygen sensing in vertebrates.

      PubDate: 2017-09-23T20:20:07Z
       
  • Elevated expression of neuropeptide signaling genes in the eyestalk
           ganglia and Y-organ of Gecarcinus lateralis individuals that are
           refractory to molt induction
    • Abstract: Publication date: Available online 18 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Natalie L. Pitts, Hanna M. Schulz, Stephanie R. Oatman, Donald L. Mykles
      Molting is induced in decapod crustaceans via multiple leg autotomy (MLA) or eyestalk ablation (ESA). MLA removes five or more walking legs, which are regenerated and become functional appendages at ecdysis. ESA eliminates the primary source of molt-inhibiting hormone (MIH) and crustacean hyperglycemic hormone (CHH), which suppress the production of molting hormones (ecdysteroids) from the molting gland or Y-organ (YO). Both MLA and ESA are effective methods for molt induction in Gecarcinus lateralis. However, some G. lateralis individuals are refractory to MLA, as they fail to complete ecdysis by 12weeks post-MLA; these animals are in the “blocked” condition. Quantitative polymerase chain reaction was used to quantify mRNA levels of neuropeptide and mechanistic target of rapamycin (mTOR) signaling genes in YO, eyestalk ganglia (ESG), thoracic ganglion (TG), and brain of intact and blocked animals. Six of the seven neuropeptide signaling genes, three of four mTOR signaling genes, and Gl-elongation factor 2 (EF2) mRNA levels were significantly higher in the ESG of blocked animals. Gl-MIH and Gl-CHH mRNA levels were higher in the TG and brain of blocked animals and levels increased in both control and blocked animals in response to ESA. By contrast, mRNA levels of Gl-EF2 and five of the 10 MIH signaling pathway genes in the YO were two to four orders of magnitude higher in blocked animals compared to controls. These data suggest that increased MIH and CHH synthesis in the ESG contributes to the prevention of molt induction by MLA in blocked animals. The up-regulation of MIH signaling genes in the YO of blocked animals suggests that the YO is more sensitive to MIH produced in the ESG, as well as MIH produced in brain and TG of ESA animals. Both the up-regulation of MIH signaling genes in the YO and of Gl-MIH and Gl-CHH in the ESG, TG, and brain appear to contribute to some G. lateralis individuals being refractory to MLA and ESA.

      PubDate: 2017-09-23T20:20:07Z
       
  • AMP-activated protein kinase protects against anoxia in Drosophila
           melanogaster
    • Abstract: Publication date: Available online 12 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Justin J. Evans, Chengfeng Xiao, R. Meldrum Robertson
      During anoxia, proper energy maintenance is essential in order to maintain neural operation. Starvation activates AMP-activated protein kinase (AMPK), an evolutionarily conserved indicator of cellular energy status, in a cascade which modulates ATP production and consumption. We investigated the role of energetic status on anoxia tolerance in Drosophila and discovered that starvation or AMPK activation increases the speed of locomotor recovery from an anoxic coma. Using temporal and spatial genetic targeting we found that AMPK in the fat body contributes to starvation-induced fast locomotor recovery, whereas, under fed conditions, disrupting AMPK in oenocytes prolongs recovery. By evaluating spreading depolarization in the fly brain during anoxia we show that AMPK activation reduces the severity of ionic disruption and prolongs recovery of electrical activity. Further genetic targeting indicates that glial, but not neuronal, AMPK affects locomotor recovery. Together, these findings support a model in which AMPK is neuroprotective in Drosophila.

      PubDate: 2017-09-18T05:31:42Z
       
  • Does aerobic capacity predict the spatial position of individuals within
           schools in juvenile qingbo (Spinibarbus sinensis)'
    • Abstract: Publication date: Available online 9 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ling-Qing Zeng, Cheng Fu, Shi-Jian Fu
      Schooling behavior is an adaptive trait of important biological and ecological significance in fish species. However, the question of how aerobic capacity and environmental factors (i.e., food and water velocity) affect the spatial positioning within fish schools has received little attention. Our study measured the aerobic capacity—as indicated by standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (AS)—and swimming performance of juvenile qingbo (Spinibarbus sinensis) and filmed their schooling behavior in a swim tunnel under both a control treatment and food stimulus treatment at three water velocities (20, 30 and 40cm s−1). Neither aerobic capacity nor swimming performance was related to spatial position within schools. Food stimulation did not trigger any change in the characteristics of spatial position at three water velocities. However, an intra-school positional preference was found between water velocities under the control treatment and food stimulus treatment. Individuals who preferred the rear of the school had smaller coefficients of variation in position under the two treatments, but this behavior was not correlated with any parameters for metabolic rates. Inter-school social interaction level, as indicated by total chase times, was not affected by either water velocity or food appearance. Although aerobic capacity and food stimulus did not influence the spatial position of individuals within schools, individual qingbo had spatial positional preferences within schools between different water speeds.

      PubDate: 2017-09-11T04:20:34Z
       
  • Physiological and behavioral responses to salinity in coastal dice snakes
    • Abstract: Publication date: Available online 8 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): François Brischoux, Yurii V. Kornilev, Harvey B. Lillywhite
      Secondarily marine tetrapods have evolved adaptations to maintain their osmotic balance in a hyperosmotic environment. During the transition to a marine habitat, the evolution of a euryhaline physiology likely encompassed successive changes in behavior and physiology that released organisms from regular access to fresh water. Deciphering these key steps is a complicated task. In this study, we investigated a species of freshwater natricine snake in which some populations are known to use marine environments. We experimentally subjected 30 adult Dice snakes (Natrix tessellata) from a population inhabiting the Black Sea coast to three salinities corresponding to freshwater (~0.1‰), brackish water (~15.0‰), and full-strength seawater (~34.0‰) in order to investigate their physiological (variation of body mass, osmolality) and behavioral (activity, drinking behavior) responses to salinity. Our results show that coastal Dice snakes from the study population are relatively tolerant to salinity close to that recorded in the Black Sea, but that prolonged exposure to full-strength seawater increases osmolality, stimulates thirst, decreases the activity of snakes and may ultimately jeopardize survival. Collectively with previously published data, our results strongly suggest specific physiological adaptations to withstand hyperosmolality rather than to reduce intake of salt, in coastal populations or species of semi-aquatic snakes. Future comparative investigations of Dice snakes from populations restricted to freshwater environment might reveal the functional traits and the behavioral and physiological responses of coastal N. tessellata to life in water with elevated salinity.

      PubDate: 2017-09-11T04:20:34Z
       
  • Extrinsic nerves are not involved in branchial 5-HT dynamics or pulsatile
           urea excretion in Gulf toadfish, Opsanus beta
    • Abstract: Publication date: Available online 6 September 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Maria C. Cartolano, Molly H.B. Amador, Velislava Tzaneva, William K. Milsom, M. Danielle McDonald
      Gulf toadfish (Opsanus beta) can switch from continuously excreting ammonia as their primary nitrogenous waste to excreting predominantly urea in distinct pulses. Previous studies have shown that the neurotransmitter serotonin (5-HT) is involved in controlling this process, but it is unknown if 5-HT availability is under central nervous control or if the 5-HT signal originates from a peripheral source. Following up on a previous study, cranial nerves IX (glossopharyngeal) and X (vagus) were sectioned to further characterize their role in controlling pulsatile urea excretion and 5-HT release within the gill. In contrast to an earlier study, nerve sectioning did not result in a change in urea pulse frequency. Total urea excretion, average pulse size, total nitrogen excretion, and percent ureotely were reduced the first day post-surgery in nerve-sectioned fish but recovered by 72h post-surgery. Nerve sectioning also had no effect on toadfish urea transporter (tUT), 5-HT transporter (SERT), or 5-HT2A receptor mRNA expression or 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) abundance in the gill, all of which were found consistently across the three gill arches except 5-HIAA, which was undetectable in the first gill arch. Our findings indicate that the central nervous system does not directly control pulsatile urea excretion or local changes in gill 5-HT and 5-HIAA abundance.

      PubDate: 2017-09-11T04:20:34Z
       
  • Hypoxic acclimation leads to metabolic compensation after reoxygenation in
           Atlantic salmon yolk-sac alevins
    • Abstract: Publication date: November 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 213
      Author(s): Elias T. Polymeropoulos, Nicholas G. Elliott, Peter B. Frappell
      Hypoxia is common in aquatic environments and has substantial effects on development, metabolism and survival of aquatic organisms. To understand the physiological effects of hypoxia and its dependence on temperature, metabolic rate ( M ̇ O 2 ) and cardiorespiratory function were studied in response to acute hypoxia (21→5kPa) at different measurement temperatures (Ta; 4, 8 and 12°C) in Salmo salar alevins that were incubated under normoxic conditions (PO2 =21kPa) or following hypoxic acclimation (PO2 =10kPa) as well as two different temperatures (4°C or 8°C). Hypoxic acclimation lead to a developmental delay manifested through slower yolk absorption. The general response to acute hypoxia was metabolic depression (~60%). Hypoxia acclimated alevins had higher M ̇ O 2 s when measured in normoxia than alevins acclimated to normoxia. M ̇ O 2 s were elevated to the same degree (~30% per 4°C change) irrespective of Ta. Under severe, acute hypoxia (~5kPa) and irrespective of Ta or acclimation, M ̇ O 2 s were similar between most groups. This suggests that despite different acclimation regimes, O2 transport was limited to the same degree. While cardiorespiratory function (heart-, ventilation rate) was unchanged in response to acute hypoxia after normoxic acclimation, hypoxic acclimation led to cardiorespiratory changes predominantly in severe hypoxia, indicating earlier onset and plasticity of cardiorespiratory control mechanisms. Although M ̇ O 2 in normoxia was higher after hypoxic acclimation, at the respective acclimation PO2 , M ̇ O 2 was similar in normoxia and hypoxia acclimated alevins. This is indicative of metabolic compensation to an intrinsic M ̇ O 2 at the acclimation condition in hypoxia-acclimated alevins after re-exposure to normoxia.

      PubDate: 2017-09-06T02:11:09Z
       
  • The effects of fluctuating temperature regimes on the embryonic
           development of lake whitefish (Coregonus clupeaformis)
    • Abstract: Publication date: Available online 30 August 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Michael Y.-T. Lim, Richard G. Manzon, Christopher M. Somers, Douglas R. Boreham, Joanna Y. Wilson
      Fluctuating incubation temperatures may have significant effects on fish embryogenesis; yet most laboratory-based studies use constant temperatures. For species that experience large, natural seasonal temperature changes during embryogenesis, such as lake whitefish (Coregonus clupeaformis), seasonal temperature regimes are likely optimal for development. Anthropogenic activities can increase average and/or variability of natural incubation temperatures over large (e.g. through climate change) or smaller (e.g. thermal effluent discharge) geographic scales. To investigate this, we incubated lake whitefish embryos under constant (2, 5, or 8°C) and fluctuating temperature regimes. Fluctuating temperature regimes had a base temperature of 2°C with: 1) seasonal temperature changes that modelled natural declines/inclines; 2) tri-weekly +3°C, 1h temperature spikes; or 3) both seasonal temperature changes and temperature spikes. We compared mortality to hatch, morphometrics, and heart rate at three developmental stages. Mortality rate was similar for embryos incubated at constant 2°C, constant 5°C, or with seasonal temperatures, but was significantly greater at constant 8°C. Embryos incubated constantly at >2°C had reduced body growth and yolk consumption compared to embryos incubated with seasonal temperature changes. When measured at the common base temperature of 2°C, embryos incubated at constant 2°C had lower heart rates than embryos incubated with both seasonal temperature changes and temperature spikes. Our study suggests that incubating lake whitefish embryos with constant temperatures may significantly alter development, growth, and heart rate compared to incubating with seasonal temperature changes, emphasizing the need to include seasonal temperature changes in laboratory-based studies.

      PubDate: 2017-09-06T02:11:09Z
       
  • An essential role of Rieske domain oxygenase Neverland in the molting
           cycle of black tiger shrimp, Penaeus monodon
    • Abstract: Publication date: Available online 24 August 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ponsit Sathapondecha, Sakol Panyim, Apinunt Udomkit
      Molting is an important process for development and growth in arthropods. In crustaceans, molt is regulated by ecdysteroids or molting hormones that are synthesized in Y-organs. However, ecdysteroid biosynthesis pathway in crustaceans and its participating enzymes have not been well studied so far. In this study, a Rieske domain oxygenase, the enzyme that acts as cholesterol 7,8-dehydrogenase by converting cholesterol to 7-dehydrocholesterol in the first step of the ecdysteroid biosynthesis was characterized in black tiger shrimp, Penaeus monodon. A full-length cDNA of P. monodon's Rieske domain oxygenase Neverland (PmNvd) was successfully cloned. The expression of PmNvd was dominantly found in the Y-organ, and changed during molting period. The PmNvd mRNA level was low in intermolt and early premolt stages, then dramatically increased in the mid premolt stage suggesting its role in molt regulation. The function of PmNvd in the molting process was investigated by RNAi approach. Silencing of PmNvd transcript in shrimp by specific double-stranded RNA (dsNvd) led to prolonged molt duration with abnormal molting progression, i.e. the molting process got stuck at early premolt stage. In addition, 20-hydroxyecdysone titer in the hemolymph of dsNvd-injected shrimp was significantly reduced compared with that in NaCl-injected shrimp. These evidences suggested a crucial role of PmNvd in molt progression, particularly during the initiation of premolt phase via the regulation of ecdysteroid production.

      PubDate: 2017-08-26T08:00:28Z
       
  • Hypoxia acclimation increases novelty response strength during fast-starts
           in the African mormyrid, Marcusenius victoriae
    • Abstract: Publication date: Available online 24 August 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kerri Lynn Ackerly, Lauren J. Chapman, Rüdiger Krahe
      Many fishes perform quick and sudden swimming maneuvers known as fast-starts to escape when threatened. In pulse-type weakly electric fishes these responses are accompanied by transient increases in the rate of electric signal production known as novelty responses. While novelty responses may increase an individual's information about their surroundings, they are aerobically powered and may come at a high energetic cost when compared to fast-starts, which rely primarily on anaerobic muscle. The juxtaposition between two key aspects of fast-starts in these fishes – the aerobic novelty response and the anaerobic swimming performance – makes them an interesting model for studying effects of hypoxia on escape performance and sensory information acquisition. We acclimated the hypoxia-tolerant African mormyrid Marcusenius victoriae to either high or low dissolved oxygen (DO) levels for 8weeks, after which fast-starts and novelty responses were quantified under both high (normoxic) and low-DO (hypoxic) test conditions. Hypoxia-acclimated fish exhibited higher maximum curvature than normoxia-acclimated fish. Displacement of normoxia-acclimated fish was not reduced under acute hypoxic test conditions. Novelty responses were given upon each startle, whether or not the fish performed a fast-start; however, novelty responses associated with fast-starts were significantly stronger than those without, suggesting a functional link between fast-start initiation and the motor control of the novelty response. Overall, hypoxia-acclimated individuals produced significantly stronger novelty responses during fast-starts. We suggest that increased novelty response strength in hypoxia-acclimated fish corresponds to an increased rate of sensory sampling, which may compensate for potential negative effects of hypoxia on higher-level processing.

      PubDate: 2017-08-26T08:00:28Z
       
  • Molecular characterization of kiss2 and differential regulation of
           reproduction-related genes by sex steroids in the hypothalamus of
           half-smooth tongue sole (Cynoglossus semilaevis)
    • Abstract: Publication date: Available online 16 August 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Bin Wang, Quan Liu, Xuezhou Liu, Yongjiang Xu, Xuesong Song, Bao Shi
      Kisspeptin (Kiss) plays a critical role in mediating gonadal steroid feedback to the gonadotropin-releasing hormone (GnRH) neurons in mammals. However, little information regarding the regulation of kisspeptin gene by sex steroids is available in teleosts. In this study, we examined the direct actions of estradiol (E2) and testosterone (T) on hypothalamic expression of kisspeptin and other key factors involved in reproductive function of half-smooth tongue sole. As a first step, a partial-length cDNA of kiss2 was identified from the brain of tongue sole and kiss2 transcript levels were shown to be widely expressed in various tissues, notably in the ovary. Then, the actions of sex steroids on kiss2 and other reproduction-related genes were evaluated using a primary hypothalamus culture system. Our results showed that neither kiss2 nor its receptor kiss2r mRNA levels were significantly altered by sex steroids. Moreover, sex steroids did not modify hypothalamic expression of gonadotropin-inhibitory hormone (gnih) and its receptor gnihr mRNAs, either. However, E2 markedly stimulated both gnrh2 and gnrh3 mRNAs levels. Overall, this study provides insights into the role of sex steroids in the reproductive function of Pleuronectiform teleosts.

      PubDate: 2017-08-26T08:00:28Z
       
  • Characterization of two odorant binding proteins in Spodoptera exigua
           reveals functional conservation and difference
    • Abstract: Publication date: Available online 12 August 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Nai-Yong Liu, Jia-Yao Zhu, Ting Zhang, Shuang-Lin Dong
      As the first biochemical step of olfactory reception and recognition, odorant binding proteins (OBPs) have been demonstrated to be essential. Considering functional diversities of OBPs within a single species, we here extended the characterization of two other OBPs from Spodoptera exigua, belonging to insect Classic OBPs. With a combination of transcriptome and Rapid Amplification of cDNA End (RACE) approaches, two OBP genes in S. exigua were first identified, namely SexiOBP1 and OBP7. Expression pattern analysis revealed that both of them exhibited a distinct expression, where OBP1 was broadly and highly expressed in several tissues including antennae of adults whereas OBP7 was abundant only in the antennae of both sexes, strongly indicative of olfactory roles. Further, binding assays showed that the two SexiOBPs shared a common odorant-response spectrum with considerable affinities to host odorants of acetophenone, farnesol and β-ionone (K i <20μM). Specially, OBP1 could strongly bind an insect attractant β-caryophyllene (K i = 2.76μM) released by maize. Intriguingly, the major sex pheromone of S. exigua, Z9,E12-14:Ac, was the best ligand for OBP7 with K i value of 7.58μM. Ligand structural analysis revealed that the two SexiOBPs were capable of accommodating different types of ligands in shape and size, possibly implying the plasticity of binding pockets. Ultimately, comparison of binding properties among 10 SexiOBPs including the two OBPs in this study implied a cross-talk in functions, i.e. different OBPs are also suitable to accept some common odorants except for unique ligands. Taken together, this study has provided evidence for their involvements in seeking and orientation of host plants, and meanwhile indicates functional conservation and difference between OBP1 and OBP7 from S. xigua.

      PubDate: 2017-08-15T11:55:17Z
       
  • Peripheral neuropeptide Y differentially influences adipogenesis and
           lipolysis in chicks from lines selected for low or high body weight
    • Abstract: Publication date: Available online 5 August 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lingbin Liu, Guoqing Wang, Yang Xiao, Steven L. Shipp, Paul B. Siegel, Mark A. Cline, Elizabeth R. Gilbert
      Neuropeptide Y (NPY) stimulates appetite and promotes lipid deposition. We demonstrated a differential sensitivity in the food intake response to central NPY in chicks from lines selected for low (LWS) or high (HWS) body weight, but have not reported whether such differences exist in the periphery. At 5days, LWS and HWS chicks were intraperitoneally injected with 0 (vehicle), 60, or 120μg/kg BW NPY and subcutaneous adipose tissue and plasma were collected at 1, 3, 6, 12, and 24h (n =12). NPY injection increased glycerol-3-phosphate dehydrogenase (G3PDH) activity at 1 and 3h and reduced plasma NEFAs at 1 and 12h. G3PDH activity was greater in HWS than LWS while NEFAs were greater in LWS. At 1h, peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein (C/EBP)α, and microsomal triglyceride transfer protein (MTTP) mRNAs were reduced in NPY-injected chicks whereas NPY receptor 1 (NPYR1) was increased. Expression of stearoyl-CoA desaturase (SCD1) was increased by NPY at 1h in HWS but not LWS. PPARγ (3 and 6h), C/EBPβ (3h), C/EBPα (6h) and NPYR1 and 2 (24h) mRNAs were greater in NPY- than vehicle-injected chicks. At several times, adipose triglyceride lipase, MTTP, perilipin 1, NPYR1, and NPYR2 mRNAs were greater in LWS than HWS, while expression of SCD1, glycerol-3-phosphate acyltransferase 3 and lipoprotein lipase was greater in HWS than LWS. Thus, NPY promotes fat deposition and inhibits lipolysis in chicks, with line differences indicative of greater rates of lipolysis in LWS and adipogenesis in HWS.

      PubDate: 2017-08-05T11:02:51Z
       
  • The roles of metabolic thermogenesis in body fat regulation in striped
           hamsters fed high-fat diet at different temperatures
    • Abstract: Publication date: October 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 212
      Author(s): Lu-Lu Shi, Wei-Jia Fan, Ji-Ying Zhang, Xiao-Ya Zhao, Song Tan, Jing Wen, Jing Cao, Xue-Ying Zhang, Qing-Sheng Chi, De-Hua Wang, Zhi-Jun Zhao
      The metabolic thermogenesis plays important roles in thermoregulation, and it may be also involved in body fat regulation. The thermogenesis of brown adipose tissue (BAT) is largely affected by ambient temperature, but it is unclear if the roles in body fat regulation are dependent on the temperature. In the present study, uncoupling protein 1 (ucp1)-based BAT thermogenesis, energy budget and body fat content were examined in the striped hamsters fed high fat diet (HF) at cold (5°C) and warm (30°C) temperatures. The effect of 2, 4-dinitrophenol (DNP), a chemical uncoupler, on body fat was also examined. The striped hamsters showed a notable increase in body fat following the HF feeding at 21°C. The increased body fat was markedly elevated at 30°C, but was significantly attenuated at 5°C compared to that at 21°C. The hamsters significantly increased energy intake at 5°C, but consumed less food at 30°C relative to those at 21°C. Metabolic thermogenesis, indicated by basal metabolic rate, UCP1 expression and/or serum triiodothyronine levels, significantly increased at 5°C, but decreased at 30°C compared to that at 21°C. A significant decrease in body fat content was observed in DNP-treated hamsters relative to the controls. These findings suggest that the roles of metabolic thermogenesis in body fat regulation largely depend on ambient temperature. The cold-induced enhancement of BAT thermogenesis may contribute the decreased body fat, resulting in a lean mass. Instead, the attenuation of BAT thermogenesis at the warm may result in notable obesity.

      PubDate: 2017-07-21T09:12:34Z
       
  • Mitochondrial oxidative phosphorylation efficiency is upregulated during
           fasting in two major oxidative tissues of ducklings
    • Abstract: Publication date: October 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 212
      Author(s): Pierre-Axel Monternier, Loïc Teulier, Jocelyne Drai, Aurore Bourguignon, Delphine Collin-Chavagnac, Frédéric Hervant, Jean-Louis Rouanet, Damien Roussel
      Fasted endothermic vertebrates must develop physiological responses to maximize energy conservation and survival. The aim of this study was to determine the effect of 1-wk. fasting in 5-wk. old ducklings (Cairina moschata) from whole-body resting metabolic rate and body temperature to metabolic phenotype of tissues and mitochondrial coupling efficiency. At the level of whole organism, the mass-specific metabolic rate of ducklings was decreased by 40% after 1-wk. of fasting, which was associated with nocturnal Tb declines and shallow diurnal hypothermia during fasting. At the cellular level, fasting induced a large reduction in liver, gastrocnemius (oxidative) and pectoralis (glycolytic) muscle masses together with a fuel selection towards lipid oxidation and ketone body production in liver and a lower glycolytic phenotype in skeletal muscles. At the level of mitochondria, fasting induced a reduction of oxidative phosphorylation activities and an up-regulation of coupling efficiency (+30% on average) in liver and skeletal muscles. The present integrative study shows that energy conservation in fasted ducklings is mainly achieved by an overall reduction in mitochondrial activity and an increase in mitochondrial coupling efficiency, which would, in association with shallow hypothermia, increase the conservation of endogenous fuel stores during fasting.

      PubDate: 2017-07-11T02:40:38Z
       
  • The difficulty with correlations: Energy expenditure and brain mass in
           bats
    • Abstract: Publication date: October 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 212
      Author(s): Brian K. McNab, Meike Köhler
      Brain mass has been suggested to determine a mammal's energy expenditure. This potential dependence is examined in 48 species of bats. A correlation between characters may be direct or derived from shared correlations with intervening factors without a direct interaction. Basal rate of metabolism in these bats increases with brain mass: large brains are more expensive than small brains, and both brain mass and basal rate increase with body mass. Basal rate and brain mass also correlate with food habits in bats. Mass-independent basal rate weakly correlates with mass-independent brain mass, the correlation only accounting for 12% of the variation in basal rate, which disappears when the combined effects of body mass and food habits are deleted. The correlation between basal rate and brain mass seen in this and other studies usually accounts for <10% of the variation in basal rate and often <4%, even when statistically significant, a minimalist explanation for the level the basal rate. This correlation probably reflects the intermediacy of secondary factors, as occurred with food habits in bats. Most biological correlations are complicated and must be examined in detail before assurance can be given as to their bases.

      PubDate: 2017-07-11T02:40:38Z
       
  • Ovarian expression and localization of clathrin (Cltc) components in
           cutthroat trout, Oncorhynchus clarki: Evidence for Cltc involvement in
           endocytosis of vitellogenin during oocyte growth
    • Abstract: Publication date: Available online 4 July 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Hiroko Mizuta, Yuji Mushirobira, Jun Nagata, Takashi Todo, Akihiko Hara, Benjamin J. Reading, Craig V. Sullivan, Naoshi Hiramatsu
      To evaluate potential involvement of clathrin in endocytosis of vitellogenin (Vtg) by teleost oocytes, cDNAs encoding clathrin heavy chain (cltc) were cloned from ovaries of cutthroat trout. Quantitative PCR revealed three types of cltc (cltc-a1, cltc-a2, cltc-b) to be expressed in 10 different tissues including the ovary. The cltc-a1 alone exhibited a significant decrease in ovarian expression during vitellogenesis; this was correlated with a corresponding decrease in transcripts encoding the major Vtg receptor (Vtgr). No development-related changes in ovarian cltc-a2 or cltc-b transcript levels were observed. In situ hybridization revealed a strong ctlc signal in pre-vitellogenic oocytes, but not in vitellogenic oocytes. Western blotting using a rabbit antiserum (a-Cltc) raised against a recombinant Cltc preparation detected a polypeptide band with an apparent mass of ~170kDa in vitellogenic ovary extracts. Immunohistochemistry using a-Cltc revealed Cltc to be uniformly distributed throughout the ooplasm of perinucleolus stage oocytes, translocated to the periphery of lipid droplet stage oocytes, and localized to the oolemma during vitellogenesis. These patterns of cltc/Cltc distribution and abundance during oogenesis, which are identical to those previously reported for vtgr/Vtgr in this species, constitute the first empirical evidence that cltc-a1/Cltc-a1 is involved in Vtg endocytosis via the Vtgr in teleost fish.

      PubDate: 2017-07-11T02:40:38Z
       
  • Effects of nutrient and water restriction on thermal tolerance: A test of
           mechanisms and hypotheses
    • Abstract: Publication date: Available online 1 July 2017
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Katherine A. Mitchell, Leigh Boardman, Susana Clusella-Trullas, John S. Terblanche
      Nutritional deprivation or desiccation can influence thermal tolerance by impacting the insects' ability to evaporatively cool, maintain cell membrane integrity and conduct protective or repair processes. Recovery from chilling is also linked to the re-establishment of iono- and osmo-regulatory homeostasis. Here, using Mediterranean fruit fly (Ceratitis capitata, Diptera: Tephritidae), we manipulated water and nutrient availability to test the mechanistic expectation that changes in whole organism lipid and water content can elicit variation in cold or heat tolerance (scored as chill coma recovery time and heat knockdown time). We measured body condition (body water and lipid content) as well as heat shock protein 70 gene (hsp70) and protein (HSP70) levels. A significant reduction in body water content with water restriction did not translate into differences in chill coma recovery. When nutrient restriction was coupled with water deprivation, this resulted in a significant reduction (−54%) of heat knockdown time in females but male flies were unaffected. There was no evidence for an hsp70 or HSP70 response under any of the stress treatments and therefore no correlation with heat or cold tolerance. Heat hardening did decrease all hsp levels. Therefore, although body water and total body lipid content differed between the treatment groups, the contribution of these factors to thermal tolerance was inconsistent with mechanistic expectations in heat knockdown time and insignificant for chill coma recovery. These results therefore highlight that the effects of resource restriction on thermal limits in insects are mechanistically more complex than previous models of stress resistance have suggested.

      PubDate: 2017-07-11T02:40:38Z
       
 
 
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