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  Subjects -> BIOLOGY (Total: 2738 journals)
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BIOCHEMISTRY (208 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 7)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Chemical Biology     Full-text available via subscription   (Followers: 355)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 9)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 6)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 8)
Advances in Biological Chemistry     Open Access   (Followers: 5)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 8)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
African Journal of Biochemistry Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 6)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 213)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 12)
American Journal of Polymer Science     Open Access   (Followers: 18)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 237)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 29)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 17)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 8)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 9)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access   (Followers: 1)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 3)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 15)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 3)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 9)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 17)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 3)
Biochemistry     Full-text available via subscription   (Followers: 261)
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 8)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 18)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 6)
Biochimie     Hybrid Journal   (Followers: 4)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 14)
BioDrugs     Full-text available via subscription   (Followers: 7)
Bioelectrochemistry     Hybrid Journal   (Followers: 3)
Biofuels     Hybrid Journal   (Followers: 8)
Biogeochemistry     Hybrid Journal   (Followers: 8)
BioInorganic Reaction Mechanisms     Full-text available via subscription   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 11)
Biomaterials Research     Open Access  
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Full-text available via subscription   (Followers: 2)
Bioprocess     Open Access  
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 7)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 18)
BMC Biochemistry     Open Access   (Followers: 8)
BMC Chemical Biology     Open Access   (Followers: 4)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 3)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 5)
ChemBioChem     Hybrid Journal   (Followers: 2)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Journal     Hybrid Journal   (Followers: 20)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Full-text available via subscription   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 2)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 17)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 3)
Clinical Chemistry and Laboratory Medicine     Full-text available via subscription   (Followers: 6)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 3)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)

        1 2 3     

Journal Cover   Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2589 journals]
  • Ascorbic acid regulation in stress responses during acute cold exposure
           and following recovery in juvenile Chinese soft-shelled turtle (Pelodiscus
           sinensis)
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Bo-jian Chen , Cui-juan Niu , Lin Yuan
      Intense temperature change often leads to increased oxidative stress in many animals with a few exceptions, including the turtle. To date, little is known about the mechanism of protective antioxidative defenses in turtles during acute temperature change, specifically the role that the antioxidant ascorbic acid (AA) plays. In this study, Chinese soft-shelled turtles (Pelodiscus sinensis) were initially acclimated at 28°C (3wks), exposed to acute cold condition (8°C, 8h) and finally placed in recovery (28°C, 24h). L-Gulonolactone oxidase (GLO) mRNA exhibited a stable transcription pattern during the intense thermal fluctuation. GLO activity also remained stable, which validated the mRNA expression pattern. The similar Q10 values for GLO activity in the different treatment groups at incubation temperatures of 28°C and 8°C indicated that the GLO activity response to thermal change exhibited a temperature-dependent enzymatic kinetic characteristic. The AA storage was tissue-specific as well as the AA re-supply in the recovery period, with brain as the priority. Despite the insufficient transport during cold exposure, the plasma AA reservoir greatly contributed to the redistribution of AA during recovery. Depending on the prominent GLO activity, the high level of tissue-specific AA storage and the extraordinary plasma AA transport potential, the Chinese soft-shelled turtle endured severe thermal fluctuations with no apparent oxidative stress. However, the significant decrease in AA concentration in the brain tissue during acute cold exposure suggested that such a strategy may not be sufficient for prolonged cold exposure.


      PubDate: 2015-03-01T17:06:29Z
       
  • Molecular characterization and transcriptional regulation of the
           renin–angiotensin system genes in Senegalese sole (Solea
           senegalensis Kaup, 1858): Differential gene regulation by salinity
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Paula Armesto , Xavier Cousin , Emilio Salas-Leiton , Esther Asensio , Manuel Manchado , Carlos Infante
      In this work, the complete cDNA sequence encoding angiotensinogen (agt) in the euryhaline flatfish Senegalese sole was obtained. Additionally, putative coding sequences belonging to other renin–angiotensin system (RAS) genes including renin (ren), angiotensin-converting enzyme (ace), angiotensin-converting enzyme 2 (ace2), as well as angiotensin II receptor type I (agtr1) and type II (agtr2), were also identified. In juvenile tissues, agt transcripts were mainly detected in liver, ren in kidney, ace and ace2 in intestine, agtr1 in kidney and brain, and agtr2 in liver and kidney. Expression analysis of the six RAS genes after a salinity shift revealed a clear increase of agt mRNA abundance in liver just after transferring soles to high salinity water (60ppt) with a peak at 48h. Moreover, gene expression analysis in gills showed transcriptional regulation of ace and agtr1 at 48h and agtr2 at 96h after transferring soles to 60ppt. Incubation of larvae before mouth opening (until 3days post hatch; dph) at low salinity (10ppt) resulted in a coordinated transcriptional up-regulation of RAS genes. Nevertheless, no differences in mRNA abundance between salinities were observed when larvae were cultivated to low salinity after mouth opening. Whole-mount in situ hybridization (WISH) signal for agt and ace in 3dph larvae incubated at 10ppt and 35ppt confirmed that the former gene was mainly expressed in liver whereas the later gene was mainly located in pharynx and posterior gut, without pronounced differences in intensity between salinities. Possible physiological significance of all these results is discussed.


      PubDate: 2015-03-01T17:06:29Z
       
  • Effects of the static and ELF magnetic fields on the neuronal population
           activity in Morimus funereus (Coleoptera, Cerambycidae) antennal lobe
           revealed by wavelet analysis
    • Abstract: Publication date: March 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 181
      Author(s): Sladjana Spasić , Srdjan Kesić , Gordana Stojadinović , Branka Petković , Dajana Todorović
      To study the influence of a static magnetic field (SMF, 2mT) and extremely low frequency magnetic field (ELF MF, 50Hz, 2mT) on the neuronal population activity, the experiments were performed on adult longhorn beetles Morimus funereus (Coleoptera, Cerambycidae). Based on a wavelet analysis of the local field potentials (LFPs), our study showed for the first time that the effects of prolonged and repeated exposure to the ELF MF on the LFPs were irreversible within investigated time frame. The relative wavelet energy (RWE) of 4–8Hz frequency band was significantly increased after sine ELF MF (SnMF)/square ELF MF (SqMF) in comparison to the control value. The RWE of slower oscillations (1–2Hz) was significantly decreased after the repeated exposures to either SnMF or SqMF. The SqMF induced decreasing of the faster waves in the range of 64–128Hz. However, we did not prove with presented methods that exposure to the SMF for 5min produces any effects on the neuronal population activity. This study has proved the wavelet transform as a valuable tool for measuring the effects of SMF and ELF MF on the neuronal population activity in M. funereus antennal lobe.


      PubDate: 2015-03-01T17:06:29Z
       
  • Acute combined pressure and temperature exposures on a shallow-water
           crustacean: Novel insights into the stress response and high pressure
           neurological syndrome
    • Abstract: Publication date: March 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 181
      Author(s): J.P. Morris , S. Thatje , J. Ravaux , B. Shillito , D. Fernando , C. Hauton
      Little is known about the ecological and physiological processes governing depth distribution limits in species. Temperature and hydrostatic pressure are considered to be two dominant factors. Research has shown that some marine ectotherms are shifting their bathymetric distributions in response to rapid anthropogenic ocean surface warming. Shallow-water species unable to undergo latitudinal range shifts may depend on bathymetric range shifts to seek refuge from warming surface waters. As a first step in constraining the molecular basis of pressure tolerance in shallow water crustaceans, we examined differential gene expression in response to acute pressure and temperature exposures in juveniles of the shallow-water shrimp Palaemonetes varians. Significant increases in the transcription of genes coding for an NMDA receptor-regulated protein, an ADP ribosylation factor, β-actin, two heat shock protein 70kDa isoforms (HSP70), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were found in response to elevated pressure. NMDA receptors have been implicated in pathways of excitotoxic damage to neurons and the onset of high pressure neurological syndrome (HPNS) in mammals. These data indicate that the sub-lethal effects of acute barotrauma are associated with transcriptional disturbances within the nervous tissue of crustaceans, and cellular macromolecular damage. Such transcriptional changes lead to the onset of symptoms similar to that described as HPNS in mammals, and may act as a limit to shallow water organisms' prolonged survival at depth.


      PubDate: 2015-03-01T17:06:29Z
       
  • Baseline defense system of commercial male king crab Lithodes santolla
           from the Beagle Channel
    • Abstract: Publication date: March 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 181
      Author(s): N. Schvezov , G.A. Lovrich , O. Florentín , M.C. Romero
      Environmental and physiological variations influence the steady-state concentration of free oxygen radicals in cells. Because of the seasonal life cycle of Lithodes santolla in the Beagle Channel, a baseline study of the antioxidant physiological variations along the seasons is necessary for a better understanding of its ecophysiology. The aim of this study was to evaluate the seasonal variations in gills, hemolymph, muscle and hepatopancreas of the: i) enzymatic activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione transferase; ii) ascorbic acid and total glutathione; iii) lipid peroxidation and protein oxidation; iv) glucose, proteins and pH. Seasonality found in the antioxidant defense system of L. santolla from the Beagle Channel acts in a collaborative way during the most relevant life cycle phases (reproduction and molting), avoiding a long term oxidative stress. The antioxidant system also shows changes in the enzymatic activities likely caused by the environmental factors, such as low temperatures during winter and spring seasons.


      PubDate: 2015-03-01T17:06:29Z
       
  • Editorial Board
    • Abstract: Publication date: March 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 181




      PubDate: 2015-03-01T17:06:29Z
       
  • Nutritional stress in Northern gannets during an unprecedented low
           reproductive success year: Can extreme sea surface temperature event and
           dietary change be the cause'
    • Abstract: Publication date: March 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 181
      Author(s): Cynthia D. Franci , François Vézina , François Grégoire , Jean-François Rail , Jonathan Verreault
      Reproductive success of seabirds is tightly associated with availability of their prey for which the spatiotemporal distribution may be influenced by sea surface temperature (SST) fluctuations. The objective of this study was to investigate whether Northern gannets (Morus bassanus) from the largest colony in North America (Bonaventure Island, Quebec, Canada) were in negative nutritional state during the unprecedented low reproductive success year of 2012, and whether this was associated with changes in SST anomalies and diet. The incubation period of gannets in 2012 was characterized by a significant decline, from early to late incubation, in plasma triglyceride levels that was associated with an increase in plasma corticosterone levels. However, no changes in plasma glycerol and β-hydroxybutyrate levels were noted. SST anomalies recorded in this area (south of the Gulf of St. Lawrence) during the breeding period were consistently higher in 2012 compared to the previous year (a better reproductive success year). Based on signatures of stable carbon (δ13C) and nitrogen (δ15N) isotopes in gannet red blood cells and in whole fish homogenates of three major preys (mackerel, herring, and capelin), a minor dietary shift was noted between those years and incubation periods. In light of these findings, it is suggested that the extreme warm-water perturbation event that prevailed in the Gulf of St. Lawrence during summer 2012 was associated with a rapid deterioration of nutritional condition of Bonaventure Island gannets during the incubation. These suboptimal physiological changes likely contributed to the dramatic decline in reproductive success reported in this colony.


      PubDate: 2015-03-01T17:06:29Z
       
  • Effect of long-afterglow phosphorescent pigment on reproductive parameters
           
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Young Jae Choi , Bong-Seok Kim , Cheol Young Choi
      Photoperiod is considered the most important factor that entrains animal rhythms, including the reproductive cycle. The present study tested differences in sex maturation and sex steroid hormones of yellowtail damselfish (Chrysiptera parasema) exposed to a white fluorescent bulb (12L:12D and 14L:10D) or long-afterglow phosphorescent pigment (LumiNova sheet) for 4months. At the end of the experiment, in the phosphorescent group, mRNA expressions of gonadotropin hormones [(GTHs, including gonadotropin (GTH) α and luteinizing hormone (LH) β)], estrogen receptor (ER), and vitellogenin were significantly higher than in the photoperiod groups (12L:12D and 14L:10D), and these results are consistent with those of Western blotting for protein expression. Furthermore, in the phosphorescent group, plasma FSH, LH, and estradiol-17β (E2) levels were significantly higher than in the photoperiod groups. However, plasma melatonin levels were significantly lower than in the photoperiod groups. Because LumiNova sheets continue to emit green light (520nm) for approximately 2h after sunset, the extended light conditions probably contributed to reproductive ability in the experimental fish. In conclusion, long-afterglow phosphorescent pigment can be used for energy-efficient aquaculture to regulate the reproduction of fish, although its effect needs to be evaluated in other species.


      PubDate: 2015-03-01T17:06:29Z
       
  • Impact of long-term moderate hypercapnia and elevated temperature on the
           energy budget of isolated gills of Atlantic cod (Gadus morhua)
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Cornelia M. Kreiss , Katharina Michael , Christian Bock , Magnus Lucassen , Hans-O. Pörtner
      Effects of severe hypercapnia have been extensively studied in marine fishes, while knowledge on the impacts of moderately elevated CO2 levels and their combination with warming is scarce. Here we investigate ion regulation mechanisms and energy budget in gills from Atlantic cod acclimated long-term to elevated PCO2 levels (2500μatm) and temperature (18°C). Isolated perfused gill preparations were established to determine gill thermal plasticity during acute exposures (10–22°C) and in vivo costs of Na+/K+-ATPase activity, protein and RNA synthesis. Maximum enzyme capacities of F1Fo-ATPase, H+-ATPase and Na+/K+-ATPase were measured in vitro in crude gill homogenates. After whole animal acclimation to elevated PCO2 and/or warming, branchial oxygen consumption responded more strongly to acute temperature change. The fractions of gill respiration allocated to protein and RNA synthesis remained unchanged. In gills of fish CO2-exposed at both temperatures, energy turnover associated with Na+/K+-ATPase activity was reduced by 30% below rates of control fish. This contrasted in vitro capacities of Na+/K+-ATPase, which remained unchanged under elevated CO2 at 10°C, and earlier studies which had found a strong upregulation under severe hypercapnia. F1Fo-ATPase capacities increased in hypercapnic gills at both temperatures, whereas Na+/K+ATPase and H+-ATPase capacities only increased in response to elevated CO2 and warming indicating the absence of thermal compensation under CO2. We conclude that in vivo ion regulatory energy demand is lowered under moderately elevated CO2 levels despite the stronger thermal response of total gill respiration and the upregulation of F1Fo-ATPase. This effect is maintained at elevated temperature.


      PubDate: 2015-03-01T17:06:29Z
       
  • AVT and IT regulate ion transport across the opercular epithelium of
           killifish (Fundulus heteroclitus) and gilthead sea bream (Sparus aurata)
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Juan Antonio Martos-Sitcha , Gonzalo MartínezRodríguez , Juan Miguel Mancera , Juan Fuentes
      The regulatory role of arginine vasotocin (AVT) and isotocin (IT) in Cl− secretion was investigated with the short circuit current (Isc) technique in opercular epithelia of killifish (Fundulus heteroclitus) and gilthead sea bream (Sparus aurata). Sea bream operculum showed ~4-fold lower number of Na/K-ATPase immunoreactive cells and ~12-fold lower secretory current than the killifish. In sea bream opercular membranes, the basolateral addition of AVT (10−6 M) significantly stimulated Cl− secretion, while IT (10−6 M) was without effect. In killifish, IT produced an immediate dose-dependent stimulation of Cl− secretion with significant effect at doses ≥10−7 M and stimulation maxima (∆Isc ~25μA⋅cm−2) at 10−6 M. The basolateral addition of bumetanide (200μM) abolished >75% of the effect of IT on Cl− secretion. In turn, AVT had a dual effect on killifish opercular Isc: an immediate response (~3min) with Isc reduction in an inverted bell-shaped dose–response manner with higher current decrease (−22μA⋅cm−2) at 10−8 M AVT, and a sustained dose-dependent stimulation of Cl− secretion (stable up to 1h), with a threshold significant effect at 10−8 M and maximal stimulation (~20μA⋅cm−2) at 10−6 M. Both effects of AVT appear receptor type specific. The V1-receptor antagonist SR 49059 abolished Isc reduction in response to AVT, while the specific V2-receptor antagonist (Tolvaptan, 1μM) abolished the stimulatory action of AVT on Cl− secretion. According to these results, we propose a modulatory role for AVT and IT in Cl− (NaCl) secretion across the opercular epithelium of marine teleost.


      PubDate: 2015-03-01T17:06:29Z
       
  • Regulation of salmonid fish sperm motility by osmotic shock-induced water
           influx across the plasma membrane
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Gen Leon Takei , Chinatsu Mukai , Makoto Okuno
      The motility of salmonid fish sperm is initiated by a decrease in the extracellular K+ concentration. However, our previous studies revealed that salmonid fish sperm motility could be initiated in the presence of an inhibitory concentration of K+ by drastic osmotic shock induced by suspension in a hypertonic glycerol solution and subsequent dilution in a hypotonic solution (glycerol-treatment). In the present study, we examined if an osmotic shock-induced water influx is involved in the regulation of salmonid fish sperm motility. HgCl2, a common inhibitor of aquaporins (AQPs), decreased the duration of salmonid fish sperm motility. Dilution of sperm cells in a hypotonic solution increased the cellular volume, whereas HgCl2 inhibited such an increase in cellular volume. Furthermore, the expression of AQP 1a and 10 in rainbow trout testes was confirmed. In contrast, HgCl2 did not affect glycerol-treated sperm motility, indicating that AQPs are not involved in glycerol-treated sperm motility. We also explored the possibility of aquaporin-independent water influx in glycerol-treated sperm by assessing the sperm membrane permeability using propidium iodide. The plasma membrane of glycerol-treated sperm was considerably permeabilized. The cellular volume was decreased in a hypertonic glycerol solution and increased upon subsequent hypoosmotic shock, indicating an AQP-independent water flux across the plasma membrane upon glycerol-treatment. Taken together, these results showed that water influx across the plasma membrane via AQP is crucial for the maintenance of salmonid fish sperm motility under normal conditions, whereas water influx by osmotic shock-induced membrane permeation is critical for the initiation of glycerol-treated sperm motility.


      PubDate: 2015-03-01T17:06:29Z
       
  • Activation of AMP-activated protein kinase in response to temperature
           elevation shows seasonal variation in the zebra mussel, Dreissena
           polymorpha
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Jennifer A. Jost , Sarah S. Keshwani , Jacob J. Abou-Hanna
      Global climate change is affecting ectothermic species, and a variety of studies are needed on thermal tolerances, especially from cellular and physiological perspectives. This study utilized AMP-activated protein kinase (AMPK), a key regulator of cellular energy levels, to examine the effects of high water temperatures on zebra mussel (Dreissena polymorpha) physiology. During heating, AMPK activity increased as water temperature increased to a point, and maximum AMPK activity was detected at high, but sublethal, water temperatures. This pattern varied with season, suggesting that cellular mechanisms of seasonal thermal acclimatization affect basic metabolic processes during sublethal heat stress. There was a greater seasonal variation in the water temperature at which maximum AMPK activity was measured than in lethal water temperature. Furthermore, baseline AMPK activity varied significantly across seasons, most likely reflecting altered metabolic states during times of growth and reproduction. In addition, when summer-collected mussels were lab-acclimated to winter and spring water temperatures, patterns of heat stress mirrored those of field-collected animals. These data suggest that water temperature is the main driver of the seasonal variation in physiology. This study concluded that AMPK activity, which reflects changes in energy supply and demand during heat stress, can serve as a sensitive and early indicator of temperature stress in mussels.


      PubDate: 2015-03-01T17:06:29Z
       
  • Adaptations of a deep sea scavenger: High ammonia tolerance and active
           NH4+ excretion by the Pacific hagfish (Eptatretus stoutii)
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Alexander M. Clifford , Greg G. Goss , Michael P. Wilkie
      The Pacific hagfish (Eptatretus stoutii) has an exceptional ability to both withstand and recover from exposure to high external ammonia (HEA). This tolerance is likely due to the feeding behavior of this scavenger, which feeds on intermittent food falls of carrion (e.g. fish, large marine mammals) during which time it may be exposed to high concentrations of total ammonia (T Amm =NH3 +NH4 +) while burrowed inside the decomposing carcass. Here we exposed hagfish to 20mmolL−1 T Amm for periods of up to 48h and then let animals recover in ammonia-free seawater. During the 48h HEA exposure period, plasma T Amm increased 100-fold to over 5000μmolL−1 while ammonia excretion (J amm) was transiently inhibited. This increase in plasma T Amm resulted from NH3 influx down massive inwardly directed ΔP NH3 gradients, which also led to a short-lived metabolic alkalosis. Plasma [T Amm] stabilized after 24–48h, possibly through a reduction in NH3 permeability across the body surface, which lowered NH3 influx. Ammonia balance was subsequently maintained through the re-establishment of J amm against an inwardly directed ΔP NH3. Calculations of the Nernst potential for ammonia strongly indicated that J amm was also taking place against a large inwardly directed NH4 + electrochemical gradient. Recovery from HEA in ammonia-free water was characterized by a large ammonia washout, and the restoration of plasma T Amm concentrations to near control concentrations. Ammonia clearance was also accompanied by a residual metabolic acidosis, which likely offset the ammonia-induced metabolic alkalosis seen in the early stages of HEA exposure. We conclude that restoration of J amm by the Pacific hagfish during ammonia exposure likely involves secondary active transport of NH4 +, possibly mediated by Na+/NH4 + (H+) exchange.


      PubDate: 2015-03-01T17:06:29Z
       
  • Variation in quantity and composition of cuticular hydrocarbons in the
           scorpion Buthus occitanus (Buthidae) in response to acute exposure to
           desiccation stress
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): E. Gefen , S. Talal , O. Brendzel , A. Dror , A. Fishman
      Scorpions exhibit some of the lowest recorded water loss rates among terrestrial arthropods. Evaporative water loss to the surrounding environment occurs mainly through the integument, and thus its resistance to water loss has paramount significance for the ability of scorpions to tolerate extremely dry habitats. Cuticular hydrocarbons (HCs) deposited on the outer epicuticle play an important role in determining cuticular waterproofing, and seasonal variation in both cuticular HC quantity and composition has been shown to correlate with water loss rates. Precursor incorporation rates into cuticle HCs have been observed to be extremely low in scorpions compared with insects. We therefore used adult male Buthus occitanus (Buthidae) in order to test HC profile plasticity during acute exposure to 14d and 28d of experimental desiccation. Cuticular HC profile of hydrated scorpions was similar to that reported for several other scorpion species, consisting of similar fractions of n-alkanes and branched alkanes, with no evidence for unsaturation. Most abundant of the n-alkanes were n-heptacosane (C27; 19±2% of total HCs), n-nonacosane (C29; 16±1%) and n-hentriacontane (C31; 11±1%). Exposure to desiccation stress resulted in a significant increase in the total amount of extracted HCs, and in the relative abundance of branched alkanes at the expense of n-alkanes. Together with an increase in HC chain lengths, these changes mimic previously-reported seasonal variation among freshly-collected specimens. This indicates that scorpions respond to water shortage by regulating the properties of their passive integumental barrier to water loss.


      PubDate: 2015-03-01T17:06:29Z
       
  • Chronic hypercapnic incubation increases relative organ growth and reduces
           blood pressure of embryonic American alligator (Alligator
           mississippiensis)
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): John Eme , Dane A. Crossley II
      Reptilian nests can experience natural hypoxic and hypercapnic conditions. We incubated alligator eggs at a female-only producing temperature (30°C) in three conditions: 21% O2/0.04% CO2, 21% O2/3.5% CO2 and 21% O2/7% CO2. Alligator embryos chronically incubated in high CO2 were markedly hypotensive (blood pressure reduced by 46%) and had relatively (mass-specific) enlarged hearts (dry mass increased by 20%), lungs (dry mass increased by 17%), and kidneys (dry mass increased by 14%). This study is the first to chronically incubate reptilian eggs in hypercapnia and suggests that high CO2 alters the cardiovascular phenotype of alligator embryos (low blood pressure, relatively enlarged hearts), as well as the relative size of the organs primarily responsible for acid base balance, lungs and kidneys. The lungs and kidneys are largely non-functional during embryonic development, and the embryonic phenotype of increased relative mass may be a predictive-adaptation to metabolic or respiratory acidosis, such as during exercise or high respiratory CO2. This study demonstrates that phenotypic plasticity of alligator embryos incubated in high CO2 may result in either preferential organ growth, or maintenance of organ growth with reduced somatic growth.


      PubDate: 2015-03-01T17:06:29Z
       
  • Maternal dietary protein supplement confers long-term sex-specific
           beneficial consequences of obesity resistance and glucose tolerance to the
           offspring in Brandt's voles
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Mei-Fang Lou , Wei Shen , Rong-Shu Fu , Xue-Ying Zhang , De-Hua Wang
      Maternal under- or over-nutrition not only alters neonatal body mass but also increases the risk of metabolic disorders in adulthood. Little is known about how maternal dietary protein affects offspring fitness in wild rodents. The present study was conducted to test the hypothesis that maternal dietary protein supplement has a long-term beneficial effect on offspring fitness in Brandt's vole (Lasiopodomys brandtii), a herbivorous rodent model. The vole dams were fed either a control (18% protein) or high-protein (36% protein) diet throughout pregnancy and lactation. After weaning, all offspring received a control diet till 14weeks old. Energetic parameters, serum leptin concentration and glucose tolerance were measured. The adult offspring were fed high-fat diet for 8weeks, and body weight and food intake were measured. No difference was observed in litter size, litter mass or pup mass before weaning. Maternal protein supplement increased body mass and the mass of reproductive organ but decreased digestibility and fat deposition and alleviated HFD-induced obesity especially in the males. Glucose tolerance was elevated in the offspring from maternal protein supplement, especially in the females. The accelerated growth may be associated with high serum leptin concentration at weaning, a state of leptin resistance, and the low digestibility may predispose obesity resistance especially in male offspring from maternal high-protein diet. These data demonstrate that maternal protein supplement confers the long-term sex-specific beneficial consequences of accelerated growth and improved obesity resistance and glucose tolerance of their offspring.


      PubDate: 2015-03-01T17:06:29Z
       
  • Transepithelial resistance and claudin expression in trout RTgill-W1 cell
           line: Effects of osmoregulatory hormones
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Rebecca T. Trubitt , D. Brett Rabeneck , Joanna K. Bujak , Maryline C. Bossus , Steffen S. Madsen , Christian K. Tipsmark
      In the present study, we examined the trout gill cell line RTgill-W1 as a possible tool for in vitro investigation of epithelial gill function in fish. After seeding in transwells, transepithelial resistance (TER) increased until reaching a plateau after 1–2days (20–80Ω⋅cm2), which was then maintained for more than 6days. Tetrabromocinnamic acid, a known stimulator of TER via casein kinase II inhibition, elevated TER in the cell line to 125% of control values after 2 and 6h. Treatment with ethylenediaminetetraacetic acid induced a decrease in TER to <15% of pre-treatment level. Cortisol elevated TER after 12–72h in a concentration-dependent manner, and this increase was antagonized by growth hormone (Gh). The effects of three osmoregulatory hormones, Gh, prolactin, and cortisol, on the mRNA expression of three tight junction proteins were examined: claudin-10e (Cldn-10e), Cldn-30, and zonula occludens-1 (Zo-1). The expression of cldn-10e was stimulated by all three hormones but with the strongest effect of Gh (50-fold). cldn-30 expression was stimulated especially by cortisol (20-fold) and also by Gh (4-fold). Finally, zo-1 was unresponsive to hormone treatment. Western blot analysis detected Cldn-10e and Cldn-30 immunoreactive proteins of expected molecular weight in samples from rainbow trout gills but not from RTgill-W1 cultures, possibly due to low expression levels. Collectively, these results show that the RTgill-W1 cell layers have tight junctions between cells, are sensitive to hormone treatments, and may provide a useful model for in vitro study of some in vivo gill phenomena.


      PubDate: 2015-03-01T17:06:29Z
       
  • Adaptation of oxidative phosphorylation to photoperiod-induced seasonal
           metabolic states in migratory songbirds
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Amit Kumar Trivedi , Shalie Malik , Sangeeta Rani , Vinod Kumar
      Eukaryotic cells produce chemical energy in the form of ATP by oxidative phosphorylation of metabolic fuels via a series of enzyme mediated biochemical reactions. We propose that the rates of these reactions are altered, as per energy needs of the seasonal metabolic states in avian migrants. To investigate this, blackheaded buntings were photoperiodically induced with non-migratory, premigratory, migratory and post-migratory phenotypes. High plasma levels of free fatty acids, citrate (an intermediate that begins the TCA cycle) and malate dehydrogenase (mdh, an enzyme involved at the end of the TCA cycle) confirmed increased availability of metabolic reserves and substrates to the TCA cycle during the premigratory and migratory states, respectively. Further, daily expression pattern of genes coding for enzymes involved in the oxidative decarboxylation of pyruvate to acetyl-CoA (pdc and pdk) and oxidative phosphorylation in the TCA cycle (cs, odgh, sdhd and mdh) was monitored in the hypothalamus and liver. Reciprocal relationship between pdc and pdk expressions conformed with the altered requirements of acetyl-CoA for the TCA cycle in different metabolic states. Except for pdk, all genes had a daily expression pattern, with high mRNA expression during the day in the premigratory/migratory phenotypes, and at night (cs, odhg, sdhd and mdh) in the nonmigratory phenotype. Differences in mRNA expression patterns of pdc, sdhd and mdh, but not of pdk, cs and odgh, between the hypothalamus and liver indicated a tissue dependent metabolism in buntings. These results suggest the adaptation of oxidative phosphorylation pathway(s) at gene levels to the seasonal alternations in metabolism in migratory songbirds.


      PubDate: 2015-03-01T17:06:29Z
       
  • Plasma insulin levels are regulated by release, rather than transcription
           or translation, in barfin flounder, Verasper moseri
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Tadashi Andoh
      We evaluated whether transcription or translation of the preproinsulin gene or insulin release into plasma is the primary regulator of plasma insulin level in barfin flounder. Three experimental groups were used: one tested 2h after feeding (Fed), one tested after fasting for 5days (Fasted), and one tested 2h after feeding following 5days of fasting (Refed). No significant differences in insulin transcription, insulin concentrations in the principal islets (PI), or plasma total insulin-like growth factor-I (IGF-I) levels were observed between the three groups. In contrast, plasma insulin level in the Fasted group was significantly lower (P<0.002) than that in the other groups. These results suggest that insulin release is the primary regulator of plasma insulin level and is more sensitive to short-term changes in nutritional conditions than IGF-I level. Furthermore, we estimated the capacity for insulin release. Based on various individual measures, the average insulin stored in the PI was 82.8μg/kg body weight (BW), and the maximum plasma content of insulin was estimated to be <1.7μg/kg BW. The half-life of plasma insulin in diabetogenic chemically (alloxan) treated flounder injected with insulin was estimated to be 2.79h, which is much longer than that in mammals, assuming a two-compartment model for the β phase. These results suggest that the capacity for insulin release in fish is ensured by at least two systems, such as the ability to store excess insulin in Brockman bodies, and enhanced efficiency of insulin storage by elongating its half-life.


      PubDate: 2015-03-01T17:06:29Z
       
  • Solute and particle retention in a small grazing antelope, the blackbuck
           (Antilope cervicapra)
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Jürgen Hummel , Sven Hammer , Catrin Hammer , Julia Ruf , Monique Lechenne , Marcus Clauss
      Digesta retention patterns have been suggested to play a major role in ruminant diversification. Two major digestion types have been proposed, termed ‘cattle-type’ and ‘moose-type’, that broadly correspond to the feeding categories of grazers and intermediate feeders on the one, and browsers on the other hand. We measured and calculated the mean retention time (MRT) of a solute and a particle (<2mm) marker in the gastrointestinal tract (GIT) and the reticulorumen (RR) of a small grazer, the Indian blackbuck (Antilope cervicapra, n=5, body mass of 26±4kg) and an intermediate feeder, the nilgai (Boselaphus tragocamelus, n=5, body mass of 168±21kg). MRTsolute and MRTparticle were 29±4.1h and 60±6.6h in blackbuck and 28±2.5h and 54±8.9h in the nilgai for the GIT, and 14±1.7h, 45±5.0h, 19±2.0h and 45±8.4h for the RR, respectively. With a selectivity factor (SF, the ratio of MRTparticle to MRTsolute) in the RR of 3.2±0.28 for blackbuck and 2.3±0.36 for nilgai, both species are clearly in the category of ‘cattle-type’ ruminants. In particular, the high SFRR of blackbuck, in spite of its small body size, is remarkable, and leads to specific predictions on the RR anatomy of this species (such as a particularly large omasum), which can be tested in further studies. The adaptive value of a high SFRR is mainly considered as an increase in microbial productivity in the RR.


      PubDate: 2015-03-01T17:06:29Z
       
  • Integrated biomarker responses of the invasive species Corbicula fluminea
           in relation to environmental abiotic conditions: A potential indicator of
           the likelihood of clam's summer mortality syndrome
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Cristiana Oliveira , Pedro Vilares , Lúcia Guilhermino
      The aim of this study was to investigate the variation of several biomarkers in wild populations of Corbicula fluminea in relation to abiotic condition changes to identify environmental factors associated with increased stress in this species potentially leading to massive mortality events. The study was carried out from July to October in the freshwater tidal areas of the estuaries of Minho and Lima Rivers (NW Iberian Peninsula). Monthly, 7 biomarkers (biotransformation, energy production, anti-oxidant defenses and lipid peroxidation damages) were determined in C. fluminea and 17 abiotic parameters were determined in water or sediments in 4 sampling sites: M1, M2 and M3 in Minho (up=> downstream); and L in Lima estuaries. The results of biomarkers were integrated using the Integrated Biomarker Response (IBR), Index and also analysed in relation to environmental parameters by Redundancy Analysis (RDA). Overall, the findings of the present study indicate that July and August are particularly stressful months for the studied C. fluminea populations, especially at downstream sites; the increase of nutrients and ammonium water concentrations, water temperature and conductivity are major contributors for this increased stress; the biomarkers indicated that in July/August C. fluminea is exposed to oxidative stress inducers, environmental chemical contaminants biotransformed by esterases and glutathione S-transferase enzymes, and that organisms need additional energy to cope with the chemical and/or thermally-induced stress. The findings of the present study stress the importance of biomonitoring the health condition of C. fluminea because it may allow determining the likelihood of summer/post summer mortality syndrome in this species.


      PubDate: 2015-03-01T17:06:29Z
       
  • Profiles of hypothalamus–pituitary–interrenal axis gene
           expression in the parr and smolt stages of rainbow trout, Oncorhynchus
           mykiss: Effects of recombinant aquaporin 3 and seawater acclimation
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Young Jae Choi , Na Na Kim , Cheol Young Choi
      The objective of this investigation was to quantify how the hypothalamus–pituitary–interrenal (HPI) axis in the rainbow trout, Oncorhynchus mykiss (parr/smolt), responds to salinity changes during transfer from freshwater (FW) to seawater (SW) and recombinant aquaporin 3 (rAQP3) injection. mRNA expression levels of HPI axis genes [corticotropic-releasing hormone (CRH) and adrenocorticotropic hormone (ACTHα and ACTHβ)] significantly increased when the fish were transferred from FW to SW (parr: 16.4-, 13.2-, 21.4-, and 11.9-fold higher than FW; smolt: 2.3-, 2.7-, 13.6-, and 6.2-fold higher than FW, respectively). Furthermore, and the plasma ACTH, Na+, Cl−, and K+ levels were the highest at 50% SW. Moreover, these parameters were significantly lower in the rAQP3-treated group than those in the control (parr: 2.0-, 2.4-, 2.1-, and 2.0-fold lower than SW; smolt: 4.2-, 1.9-, 2.4-, and 2.3-fold lower than SW, respectively). Hence, HPI axis genes may play a role in SW adaptation during migration from FW to SW environments. We showed that there was a negative correlation between rAQP3, HPI axis genes, and ion levels when the fish were transferred to SW, with levels being significantly lower in the rAQP3-injected group. Hence, cortisol appears to be a stress hormone and plasma Na+ and Cl− levels significantly increased when the fish were transferred to SW, with levels being significantly lower in the rAQP3-treated group. These results indicate that rAQP3 modulates the HPI axis and ion transportation in rainbow trout.


      PubDate: 2015-03-01T17:06:29Z
       
  • Effect of temperature on acoustic communication: Sound production in the
           croaking gourami (labyrinth fishes)
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Friedrich Ladich , Günter Schleinzer
      Sound communication comprising the production and detection of acoustic signals is affected by ambient temperature in ectothermic animals. In the present study we investigated the effects of temperature on sound production and characteristics in the croaking gourami Trichopsis vittata, a freshwater fish from Southeast Asia possessing a highly specialized sound-generating mechanism found only in a single genus. The croaking gourami produces pulsed sounds by stretching and plucking two enhanced pectoral fin tendons during rapid pectoral fin beating. Croaking sounds typically consist of a series of double-pulsed bursts with main energies between 1 and 1.5kHz. Sounds were recorded during dyadic contests between two males at three different temperatures (25°, 30° and 35°C). The mean dominant frequency increased with rising temperature from 1.18 to 1.33kHz, whereas temporal characteristics decreased. The sound interval dropped from 492 to 259ms, the burst period from 51 to 35ms and the pulse period from 5.8 to 5.1ms. In contrast, the number of sounds and number of bursts within a sound were not affected by temperature. The current study shows that spectral and temporal characteristics of sounds are affected in different ways by temperature in the croaking gourami, whereas the numbers of sounds and bursts remain unaffected. We conclude that acoustic communication in gouramis is affected by changes in ambient temperature.


      PubDate: 2015-03-01T17:06:29Z
       
  • Editorial Board
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182




      PubDate: 2015-03-01T17:06:29Z
       
  • Effects of 5α-dihydrotestosterone on expression of genes related to
           steroidogenesis and spermatogenesis during the sex determination and
           differentiation periods of the pejerrey, Odontesthes bonariensis
    • Abstract: Publication date: April 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 182
      Author(s): Anelisa González , Juan I. Fernandino , Gustavo M. Somoza
      Sex steroid hormones are important players in the control of sex differentiation by regulating gonadal development in teleosts. Although estrogens are clearly associated with the ovarian differentiation in teleosts, the effects of androgens on early gonadal development are still a matter of debate. Traditionally, 11-ketotestosterone (11-KT) is considered the major androgen in fish; however, 5α-dihydrotestosterone (5α-DHT), the most potent androgen in tetrapods, was recently found in fish testis and plasma, but its physiological role is still unknown. In this context, the expression of genes associated with steroidogenesis and spermatogenesis, body growth and sex differentiation were assessed in Odontesthes bonariensis larvae fed with food supplemented with two doses of 5α-DHT (0.1 and 10μg/g of food) from hatching to 6weeks of age. At the lowest dose, 5α-DHT treated larvae showed an estrogenic gene expression pattern, with low hsd11b2 and high cyp19a1a and er2 expression levels with no differences in sex ratio. At the highest dose, 5α-DHT produced a male-shifted sex ratio and the larvae exhibited a gene expression profile characteristic of an advancement of spermatogenesis, with inhibition of amh and stimulation of ndrg3. No differences were observed in somatic growth. These results suggest that in this species, 5α-DHT could have a role on sex differentiation and its effects can differ according to the dose.


      PubDate: 2015-03-01T17:06:29Z
       
  • The effects of temperature on the gas exchange cycle in Agathemera crassa
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Mariana Thienel , Mauricio Canals , Francisco Bozinovic , Claudio Veloso
      Insects exhibit three patterns of gas exchange: continuous (CoGE), cyclic (CGE) and discontinuous (DGE). In this work, we present the first record of a DGE in Phasmatodea and its transition to CGE and to CoGE through a thermal gradient. The rate of CO2 production (VCO2) at 10, 20 and 30°C was examined in adults of Agathemera crassa, a high-Andean phasmid of central Chile. Carbon dioxide release was recorded during 24h with L:D cycle of 12:12h in order to record both rest and activity periods. At rest, A. crassa showed three patterns of gas exchange, highlighting the use of DGE preferably at 10°C. As the temperature increased, the CoGE pattern was more frequent being the only pattern observed in all individuals at 30°C. During activity, patterns changed to CoGE with a significant increase in VCO2. Our results support the idea that gas exchange patterns in insects are not distinct but correspond to a continuum of responses addressed by metabolic demand and where DGE can be expressed only under an absolute state of rest. Our results support the idea that the presence of the DGE may be underestimated in other insect taxa because they may have been measured under conditions where this pattern not necessarily can be expressed.


      PubDate: 2015-03-01T17:06:29Z
       
  • Neuroendocrine control of appetite in Atlantic halibut (Hippoglossus
           hippoglossus): Changes during metamorphosis and effects of feeding
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Ana S. Gomes , Ann-Elise Olderbakk Jordal , Kjetil Olsen , Torstein Harboe , Deborah M. Power , Ivar Rønnestad
      Hormones and neuropeptides play a crucial role in the appetite control system of vertebrates, yet few studies have focused on their importance during early teleost development. In this study, we analysed the expression patterns of the appetite-controlling factors ghrelin, neuropeptide Y (NPY), peptide YY (PYY), pro-opiomelanocortin (POMC-C), and cocaine-amphetamine-related transcript (CART) by quantitative PCR. Transcript expression was investigated in response to feeding in developing Atlantic halibut larvae: before (premetamorphic stage 5) and during metamorphosis (stages 8 and 9B), and also in response to a fast–refeed challenge. We show that ghrelin transcript expression increased in synchrony with stomach development, while CART was significantly reduced during larval development. PYY was up-regulated 1 and 3h after feeding in stage 5. Transcript abundance of other appetite-controlling factors did not change in response to feeding. Fasting–refeeding trials (majority of larvae in metamorphosing stage 7) revealed a down-regulation of POMC-C 30min after refeeding, while ghrelin, PYY and NPY transcript expression increased 2, 4 and 5h after refeeding, respectively. In summary, transcripts for key appetite-controlling factors were detected early during development in Atlantic halibut and their emergence was not correlated with metamorphosis, with the exception of ghrelin. Our results suggest that PYY may mediate satiety early in larval development. The differing response times of POMC-C, ghrelin, PYY and NPY to a meal are intriguing and require further exploration to understand the role of each player in appetite control.


      PubDate: 2015-03-01T17:06:29Z
       
  • Physiological, cellular and biochemical thermal stress response of
           intertidal shrimps with different vertical distributions: Palaemon elegans
           and Palaemon serratus
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Diana Madeira , Vanessa Mendonça , Marta Dias , Joana Roma , Pedro M. Costa , Miguel Larguinho , Catarina Vinagre , Mário S. Diniz
      The ability to cope with high temperature variations is a critical factor in intertidal communities. Two species of intertidal rocky shore shrimps (Palaemon sp.) with different vertical distributions were collected from the Portuguese coast in order to test if they were differentially sensitive to thermal stress. Three distinct levels of biological organization (organismal, biochemical, and cellular) were surveyed. The shrimp were exposed to a constant rate of temperature increase of 1°C.h−1, starting at 20°C until reaching the CTMax (critical thermal maximum). During heat stress, two biomarkers of protein damage were quantified in the muscle via enzyme-linked immunosorbent assays: heat shock proteins HSP70 (hsp70/hsc70) and total ubiquitin. Muscle histopathological alterations caused by temperature were also evaluated. CTMax values were not significantly different between the congeners (P. elegans 33.4 ± 0.5 °C; P. serratus 33.0 ± 0.5 °C). Biomarker levels did not increase along the temperature trial, but P. elegans (higher intertidal) showed higher amounts of HSP70 and total ubiquitin than P. serratus (lower intertidal). HSP70 and total ubiquitin levels showed a positive significant correlation in both species, suggesting that their association is important in thermal tolerance. Histopathological observations of muscle tissue in P. serratus showed no gross alterations due to temperature but did show localized atrophy of muscle fibers at CTMax. In P. elegans, alterations occurred at a larger scale, showing multiple foci of atrophic muscular fascicles caused by necrotic or autolytic processes. In conclusion, Palaemon congeners displayed different responses to stress at a cellular level, with P. elegans having greater biomarker levels and histopathological alterations.


      PubDate: 2015-03-01T17:06:29Z
       
  • Effects of salinity on the accumulation of hemocyte aggregates and
           bacteria in the gills of Callinectes sapidus, the Atlantic blue crab,
           injected with Vibrio campbellii
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Jennifer L. Ikerd , Karen G. Burnett , Louis E. Burnett
      In addition to respiration and ion regulation, crustacean gills accumulate and eliminate injected particles, along with hemocyte aggregates that form in response to those particles. Here we report that the dose of Vibrio campbellii previously shown to induce a decrease in respiration and hemolymph flow across the gill in the Atlantic blue crab, Callinectes sapidus, also triggered the formation of aggregates containing four or more hemocytes in the gills, compared with saline-injected controls. More bacteria were trapped and rendered non-culturable per unit weight by anterior respiratory gills than posterior gills specialized for ion regulation. Further, more bacteria accumulated in the anterior gills of animals held at 30ppt than those at 10ppt. Thus, the role of the gills in immune defense comes at an energetic cost to this and likely to other crustaceans; this cost is influenced by acclimation salinity and the position and specialized function of individual gills.


      PubDate: 2015-03-01T17:06:29Z
       
  • Impact of dietary fatty acids on muscle composition, liver lipids, milt
           composition and sperm performance in European eel
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Ian Anthony Ernest Butts , Rosa Baeza , Josianne Gatt Støttrup , Maria Krüger-Johnsen , Charlotte Jacobsen , Luz Pérez , Juan F. Asturiano , Jonna Tomkiewicz
      In order for European eel aquaculture to be sustainable, the life cycle should be completed in captivity. Development of broodstock diets may improve the species' reproductive success in captivity, through the production of high-quality gametes. Here, our aim was to evaluate the influence of dietary regime on muscle composition, and liver lipids prior to induced maturation, and the resulting sperm composition and performance. To accomplish this fish were reared on three “enhanced” diets and one commercial diet, each with different levels of fatty acids, arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Neutral lipids from the muscle and liver incorporated the majority of the fatty acid profile, while phospholipids incorporated only certain fatty acids. Diet had an effect on the majority of sperm fatty acids, on the total volume of extractable milt, and on the percentage of motile sperm. Here, our results suggest that the total volume of extractable milt is a DHA-dependent process, as we found the diets with the highest DHA levels induced the most milt while the diet with the lowest DHA level induced the least amount of milt. The diet with the highest level of ARA induced medium milt volumes but had the highest sperm motility. EPA also seems important for sperm quality parameters since diets with higher EPA percentages had a higher volume of milt and higher sperm motility. In conclusion, dietary fatty acids had an influence on fatty acids in the tissues of male eel and this impacted sperm performance.


      PubDate: 2015-03-01T17:06:29Z
       
  • Mobilisation of blubber fatty acids of northern elephant seal pups
           (Mirounga angustirostris) during the post-weaning fast
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Caroline Louis , Laurent Perdaens , Stéphanie Suciu , Stephen K. Tavoni , Daniel E. Crocker , Cathy Debier
      Northern elephant seal pups were longitudinally sampled at Año Nuevo State Reserve during the post-weaning fast, in order to evaluate the changes of fatty acid (FA) profiles in serum as well as in the inner and outer layers of blubber. The major FAs of inner and outer blubber layers were broadly similar to those found in NES maternal milk previously measured, suggesting a direct deposit of dietary FAs in the blubber during the suckling period. The outer blubber layer contained more medium-chain monounsaturated FAs that contribute in keeping the fluidity of this tissue at cold temperatures. It was compensated by higher proportions of saturated FAs in the inner blubber layer. The FA signature of inner blubber, the layer that is mainly mobilised during energy deprivation, slightly differed from the signature of serum. There were greater proportions of medium-chain saturated FAs and ω-6 polyunsaturated FAs, and lower proportions of long-chain saturated FAs, medium-chain monounsaturated FAs and long-chain monounsaturated FAs in serum as compared to inner blubber. We also demonstrated that lipophilicity is the main factor governing the mobilisation of FAs from blubber. The least lipophilic FAs were preferentially hydrolysed from blubber, leading to an enrichment of the more lipophilic FAs in this tissue with the progression of the fast. The expression levels of HSL and ATGL, which are two enzymes involved in the lipolytic process, remained stable during the post-weaning fast. This suggests that the pups have developed the enzymatic mechanisms for an efficient lipolysis as soon as the first week of fast.


      PubDate: 2015-03-01T17:06:29Z
       
  • Estimating resting metabolic rate by biologging core and subcutaneous
           temperature in a mammal
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Benjamin Rey , Lewis G. Halsey , Robyn S. Hetem , Andrea Fuller , Duncan Mitchell , Jean-Louis Rouanet
      Tri-axial accelerometry has been used to continuously and remotely assess field metabolic rates in free-living endotherms. However, in cold environments, the use of accelerometry may underestimate resting metabolic rate because cold-induced stimulation of metabolic rate causes no measurable acceleration. To overcome this problem, we investigated if logging the difference between core and subcutaneous temperatures (ΔTc−s) could reveal the metabolic costs associated with cold exposure. Using implanted temperature data loggers, we recorded core and subcutaneous temperatures continuously in eight captive rabbits (Oryctolagus cuniculus) and concurrently measured their resting metabolic rate by indirect calorimetry, at ambient temperatures ranging from −7 to +25°C. ΔTc−s showed no circadian fluctuations in warm (+23°C) or cold (+5°C) environments implying that the ΔTc−s was not affected by an endogenous circadian rhythm in our laboratory conditions. ΔTc−s correlated well with resting metabolic rate (R2 =0.77) across all ambient temperatures except above the upper limit of the thermoneutral zone (+25°C). Determining ΔTc−s could therefore provide a complementary approach for better estimating resting metabolic rate of animals within and below their thermoneutral zone. Combining data from accelerometers with such measures of body temperature could improve estimates of the overall field metabolic rate of free-living endotherms.


      PubDate: 2015-03-01T17:06:29Z
       
  • Metabolic compensations in mitochondria isolated from the heart, liver,
           kidney, brain and white muscle in the southern catfish (Silurus
           meridionalis) by seasonal acclimation
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Yulian Yan , Xiaojun Xie
      In order to examine the effects of seasonal acclimation on mitochondrial metabolic functions and test tissue-specific pattern of the metabolic compensation within individuals of the southern catfish (Silurus meridionalis Chen), rates of mitochondrial respiration and activities of cytochrome c oxidase (COX) in the heart, liver, kidney, brain and white muscle of this fish in the summer-acclimatized group (153.20±1.66g) and winter-acclimatized group (177.71±3.04g) were measured at seven assay temperatures (7.5, 12.5, 17.5, 22.5, 27.5, 32.5 and 37.5°C), respectively. The results show that compensatory adjustments in state III respiratory rate and COX activity occur significantly in the heart, kidney and liver, but do not in the brain and white muscle, which suggest that the metabolic compensation of this fish in response to seasonal acclimation exhibits a tissue-specific pattern. The cold acclimation increases mitochondrial oxidative capacities in the heart, kidney and liver concomitantly with reducing their upper thermal limits of mitochondrial functions at acute warming and the thermal tolerance shifts in the same tissue-specific pattern as the metabolic compensation. When combining the effects of seasonal acclimation on mitochondrial oxidative capacity and organ mass, the metabolic compensation demonstrates an organ-specific pattern with four categories: over-compensation in the heart, complete compensation in the kidney, partial compensation in the liver and no compensation in the brain. The organ-specific pattern of metabolic compensation might be a trade-off strategy of the performance adjustments in the seasonal acclimation for this fish to maximize its fitness.


      PubDate: 2015-03-01T17:06:29Z
       
  • Cold induced changes in lipid, protein and carbohydrate levels in the
           tropical insect Gromphadorhina coquereliana
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Szymon Chowanski , Jan Lubawy , Marta Spochacz , Paluch Ewelina , Smykalla Grzegorz , Grzegorz Rosinski , Malgorzata Slocinska
      Insects cope with thermal stressors using mechanisms such as rapid cold hardening and acclimation. These mechanisms have been studied in temperate insects, but little is known about their use by tropical insects in response to cold stress. Here, we investigated whether cold stress (1×8h and 3×8h at 4°C) triggers a metabolic response in the Madagascar cockroach Gromphadorhina coquereliana. We examined the effects of cold on the levels of selected metabolites in the fat body tissue of G. coquereliana. After cold exposure, we found that the quantity of total protein increased significantly in the insect fat body, whereas glycogen decreased slightly. Using antibodies, we observed upregulation of AQP-like proteins and changes in the HSP70 levels in the fat body of G. coquereliana when exposed to cold. We also examined the content and nature of the free sugars in the G. coquereliana hemolymph and discovered an increase in the levels of polyols and glucose in response to cold stress. These results suggest an important role of the fat body tissue of tropical insects upon cold exposure.


      PubDate: 2015-03-01T17:06:29Z
       
  • Intestinal ammonia transport in freshwater and seawater acclimated rainbow
           trout (Oncorhynchus mykiss): Evidence for a Na+ coupled uptake mechanism
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Julian G. Rubino , Alex M. Zimmer , Chris M. Wood
      In vitro gut sac experiments were performed on freshwater and 60% seawater acclimated trout (Oncorhynchus mykiss) under treatments designed to discern possible mechanisms of intestinal ammonia transport. Seawater acclimation increased ammonia flux rate into the serosal saline (Jsamm) in the anterior intestine, however it did not alter Jsamm in the mid- or posterior intestine suggesting similar mechanisms of ammonia handling in freshwater and seawater fish. Both fluid transport rate (FTR) and Jsamm were inhibited in response to basolateral ouabain treatment, suggesting a linkage of ammonia uptake to active transport, possibly coupled to fluid transport processes via solvent drag. Furthermore, decreases in FTR and Jsamm caused by low Na+ treatment indicated a Na+ linked transport mechanism. Mucosal bumetanide (10−4 M) had no impact on FTR, yet decreased Jsamm in the anterior and mid-intestine, suggesting NH4 + substitution for K+ on an apical NKCC, and at least a partial uncoupling of ammonia transport from fluid transport. Additional treatments (amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), phenamil, bafilomycin, 4′,6-diamidino-2-phenylindole (DAPI), high sodium) intended to disrupt alternative routes of Na+ uptake yielded no change in FTR or Jsamm, suggesting the absence of direct competition between Na+ and ammonia for transport. Finally, [14C]methylamine permeability (PMA) measurements indicated the likely presence of an intestinal Rh-mediated ammonia transport system, as increasing NH4Cl (0, 1, 5mmoll−1) concentrations reduced PMA, suggesting competition for transport through Rh proteins. Overall, the data presented in this paper provide some of the first insights into mechanisms of teleost intestinal ammonia transport.


      PubDate: 2015-03-01T17:06:29Z
       
  • Food composition influences metabolism, heart rate and organ growth during
           digestion in Python regius
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Poul Secher Henriksen , Sanne Enok , Johannes Overgaard , Tobias Wang
      Digestion in pythons is associated with a large increase in oxygen consumption (SDA), increased cardiac output and growth in visceral organs assisting in digestion. The processes leading to the large postprandial rise in metabolism in snakes is subject to opposing views. Gastric work, protein synthesis and organ growth have each been speculated to be major contributors to the SDA. To investigate the role of food composition on SDA, heart rate (HR) and organ growth, 48 ball pythons (Python regius) were fed meals of either fat, glucose, protein or protein combined with carbonate. Our study shows that protein, in the absence or presence of carbonate causes a large SDA response, while glucose caused a significantly smaller SDA response and digestion of fat failed to affect metabolism. Addition of carbonate to the diet to stimulate gastric acid secretion did not increase the SDA response. These results support protein synthesis as a major contributor to the SDA response and show that increased gastric acid secretion occurs at a low metabolic cost. The increase in metabolism was supported by tachycardia caused by altered autonomic regulation as well as an increased non-adrenergic, non-cholinergic (NANC) tone in response to all diets, except for the lipid meal. Organ growth only occurred in the small intestine and liver in snakes fed on a high protein diet.


      PubDate: 2015-03-01T17:06:29Z
       
  • Effects of resveratrol on growth and skeletal muscle physiology of
           juvenile southern flounder
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Whitney N. Wilson , Bradley L. Baumgarner , Wade O. Watanabe , Md Shah Alam , Stephen T. Kinsey
      Resveratrol is a naturally occurring antioxidant that has been widely studied in mammals due to its potential to extend lifespan. However, antioxidants may also limit protein damage and therefore reduce rates of protein degradation, providing a potential avenue for enhancing growth in an aquaculture setting. The present study tested the hypotheses that in Southern flounder, Paralichthys lethostigma, resveratrol would decrease protein carbonylation and 4-HNE (indicators of protein and lipid oxidative damage, respectively), levels of ubiquitinylation and LC3 (indicators of non-lysosomal and lysosomal protein degradation, respectively), while having no effect on S6K activation (indicator of protein synthesis). These effects were predicted to increase growth rate. Mitochondrial volume density was also examined since resveratrol may lead to the proliferation of mitochondria, which are the principal source of reactive oxygen species (ROS) that cause oxidative damage. Juvenile fish (n=142) were fed a control diet or a diet supplemented with 600μg resveratrol per g of food for 16weeks. Fish treated with resveratrol had a 9% greater length and 33% greater body mass than control fish after 16weeks. Additionally, there was lower protein carbonylation and lipid 4-HNE within the muscle tissues of treated fish, indicating decreased oxidative damage, and reduced protein ubiquitinylation in the resveratrol fed flounder, indicating less protein degradation. However, there was not a significant difference in LC3, S6K activation, or mitochondrial volume density. These results suggest that resveratrol has positive effects on growth due to its antioxidant properties that reduce non-lysosomal protein degradation.


      PubDate: 2015-03-01T17:06:29Z
       
  • Ultraviolet radiation does not increase oxidative stress in the lizard
           Psammodromus algirus along an elevational gradient
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Senda Reguera , Francisco J. Zamora-Camacho , Elena Melero , Sergio García-Mesa , Cristina E. Trenzado , Marco J. Cabrerizo , Ana Sanz , Gregorio Moreno-Rueda
      Lizards, as ectotherms, spend much time basking for thermoregulating exposed to solar radiation. Consequently, they are subjected to ultraviolet radiation (UVR), which is the most harmful component of solar radiation spectrum. UVR can provoke damages, from the molecular to tissue level, even cause death. Photooxidation triggered by UVR produces reactive oxidative species (ROS). When antioxidant machinery cannot combat the ROS concentration, oxidative stress occurs in the organisms. Given that UVR increases with elevation, we hypothesised that lizards from high elevations should be better adapted against UVR than lizards from lower elevations. In this work, we test this hypothesis in Psammodromus algirus along an elevation gradient (three elevational belts, from 300 to 2500m above sea level). We ran an experiment in which lizards from each elevation belt were exposed to 5-hour doses of UVR (UV-light bulb, experimental group) or photosynthetically active radiation (white-light bulb, control group) and, 24h after the exposure, we took tissue samples from the tail. We measured oxidative damage (lipid and protein peroxidation) and antioxidant capacity as oxidative-stress biomarkers. We found no differences in oxidative stress between treatments. However, consistent with a previous work, less oxidative damage appeared in lizards from the highlands. We conclude that UVR is not a stressor agent for P. algirus; however, our findings suggest that the lowland environment is more oxidative for lizards. Therefore, P. algirus is well adapted to inhabit a large elevation range, and this would favour the lizard in case it ascends in response to global climate change.


      PubDate: 2015-03-01T17:06:29Z
       
  • Sex-related differences in steroid concentrations in the blue mussel
           (Mytilus edulis trossulus) from the southern Baltic Sea
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Sandra Zabrzańska , Katarzyna Smolarz , Anna Hallmann , Lucyna Konieczna , Tomasz Bączek , Maciej Wołowicz
      This paper reports on sex-related differences in free steroid hormone concentrations including the concentrations of three naturally occurring estrogens (17β-estradiol E2, estrone E1, and estriol E3) and one androgen (testosterone T) in the tissues (gills and gonads) of the blue mussel Mytilus edulis trossulus sampled from the Gulf of Gdańsk (Baltic Sea, Poland). The dissimilarity in steroid concentrations between tissues was particularly evident in the T concentration with a level in gills almost three times higher compared to gonads (on average, 15.38ng/g w.w. and 5.31ng/g w.w., respectively, p =0.00008), suggesting its exogenous origin. In general, a tendency towards a skewed steroid profile related to sex, with E2 more abundant for males and T for females, was observed. Female gonads were characterized by a higher level of T than testis (4.61ng/g w.w. for females and 0.70ng/g w.w. for males, p =0.0121). At the same time, the level of E2 found in the testis was higher than in the ovary (4.81ng/g w.w. and 3.86ng/g w.w., respectively); however, the difference was not statistically significant. As for gills, similar trend with T and E2 being more abundant in males was observed. At the same time, no disturbances in the sex ratio and gametogenesis process were observed which suggests i) efficient deactivation of free forms of steroids, and/or ii) their little or no physiological role.


      PubDate: 2015-03-01T17:06:29Z
       
  • Reduced resistance to oxidative stress during reproduction as a cost of
           early-life stress
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Cédric Zimmer , Karen A. Spencer
      Stress exposure during early-life development can have long-term consequences for a variety of biological functions including oxidative stress. The link between early-life stress and oxidative balance is beginning to be explored and previous studies have focused on this link in adult non-breeding or immature individuals. However, as oxidative stress is considered as the main physiological mechanism underlying the trade-off between self-maintenance and investment in reproduction, it is necessary to look at the consequences of early-life stress on oxidative status during reproduction. Here, we investigated the effects of exposure to pre- and/or post-natal stress on oxidative balance during reproduction under benign or stressful environmental conditions in an avian model species, the Japanese quail. We determined total antioxidant status (TAS), total oxidant status (TOS) and resistance to a free-radical attack in individual exposed to pre-natal stress, post-natal stress or both and in control individuals exposed to none of the stressors. TAS levels decreased over time in all females that reproduced under stressful conditions. TOS decreased between the beginning and the end of reproductive period in pre-natal control females. In all females, resistance to a free-radical attack decreased over the reproductive event but this decrease was more pronounced in females from a pre-natal stress development. Our results suggest that pre-natal stress may be associated with a higher cost of reproduction in terms of oxidative stress. These results also confirm that early-life stress can be associated with both benefits and costs depending of the life-history stage or environmental context.


      PubDate: 2015-03-01T17:06:29Z
       
  • Cloning and expression of the epithelial sodium channel and its role in
           osmoregulation of aquatic and estivating African lungfish Protopterus
           annectens
    • Abstract: Publication date: May 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 183
      Author(s): Minoru Uchiyama , Norifumi Konno , Sachika Shibuya , Satoshi Nogami
      The epithelial sodium channel (ENaC) is a sodium (Na+)-selective aldosterone-stimulated ion channel involved in Na+ transport homeostasis of tetrapods. We examined full-length cDNA sequences and tissue distributions of ENaCα, ENaCβ, and ENaCγ subunits in the African lungfish Protopterus annectens. Protopterus ENaC (pENaC) comprises 3 subunits: pENaCα, pENaCβ, and pENaCγ. pENaCα, pENaCβ, and pENaCγ subunits are closely related to α, β, and γ subunits of the Australian lungfish Neoceratodus forsteri ENaC (nENaC), respectively. Three ENaC subunit mRNAs were highly expressed in the gills and moderately expressed in the kidney and rectum of P. annectens. During estivation for 2–4weeks and 2–3months, plasma Na+ concentration was relatively stable, but plasma urea concentration significantly increased in comparison with the control fish kept in a freshwater environment. Plasma aldosterone concentration and mRNA expression of the ENaCα subunit gradually and significantly decreased in the gills and kidney after 2months of estivation. Thus, aldosterone-dependent Na+ absorption via ENaC probably exists in the epithelial cells of osmoregulatory organs of lungfish kept in fresh water, whereas plasma Na+ concentration may be maintained by a mechanism independent of aldosterone-ENaC axis during estivation in lungfish.


      PubDate: 2015-03-01T17:06:29Z
       
  • Are there intergenerational and population-specific effects of oxidative
           stress in sockeye salmon (Oncorhynchus nerka)'
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Jessica J. Taylor , Samantha M. Wilson , Natalie M. Sopinka , Scott G. Hinch , David A. Patterson , Steven J. Cooke , William G. Willmore
      Intergenerational effects of stress have been reported in a wide range of taxa; however, few researchers have examined the intergenerational consequences of oxidative stress. Oxidative stress occurs in living organisms when reactive oxygen species remain unquenched by antioxidant defense systems and become detrimental to cells. In fish, it is unknown how maternal oxidative stress and antioxidant capacity influence offspring quality. The semelparous, migratory life history of Pacific salmon (Oncorhynchus spp.) provides a unique opportunity to explore intergenerational effects of oxidative stress. This study examined the effects of population origin on maternal and developing offspring oxidative stress and antioxidant capacity, and elucidated intergenerational relationships among populations of sockeye salmon (Oncorhynchus nerka) with varying migration effort. For three geographically distinct populations of Fraser River sockeye salmon (British Columbia, Canada), antioxidant capacity and oxidative stress were measured in adult female plasma, heart, brain, and liver, as well as in developing offspring until time of emergence. Maternal and offspring oxidative stress and antioxidant capacity varied among populations but patterns were not consistent across tissue/developmental stage. Furthermore, maternal oxidative stress and antioxidant capacity did not affect offspring oxidative stress and antioxidant capacity across any of the developmental stages or populations sampled. Our results revealed that offspring develop their endogenous antioxidant systems at varying rates across populations; however, this variability is overcome by the time of emergence. While offspring may be relying on maternally derived antioxidants in the initial stages of development, they rapidly develop their own antioxidant systems (mainly glutathione) during later stages of development.


      PubDate: 2015-03-01T17:06:29Z
       
  • The concentration of plasma metabolites varies throughout reproduction and
           affects offspring number in wild brown trout (Salmo trutta)
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Zoé Gauthey , Marine Freychet , Aurélie Manicki , Alexandre Herman , Olivier Lepais , Stéphane Panserat , Arturo Elosegi , Cédric Tentelier , Jacques Labonne
      In wild populations, measuring energy invested in the reproduction and disentangling investment in gametes versus investment in reproductive behavior (such as intrasexual competition or intersexual preference) remain challenging. In this study, we investigated the energy expenditure in brown trout reproductive behavior by using two proxies: variation in weight and variation of plasma metabolites involved in energy production, over the course of reproductive season in a semi natural experimental river. We estimated overall reproductive success using genetic assignment at the end of the reproductive season. Results show that triglycerides and free fatty acid concentrations vary negatively during reproduction, while amino-acids and glucose concentrations remain stable. Decrease in triglyceride and free fatty acid concentrations during reproduction is not related to initial concentration levels or to weight variation. Both metabolite concentration variations and weight variations are correlated to the number of offspring produced, which could indicate that gametic and behavioral reproductive investments substantially contribute to reproductive success in wild brown trout. This study opens a path to further investigate variations in reproductive investment in wild populations.


      PubDate: 2015-03-01T17:06:29Z
       
  • Seasonal changes in body mass, serum leptin levels and hypothalamic
           neuropeptide gene expression in male Eothenomys olitor
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Zhu Wan-long , Wang Zheng-kun
      The present study examined seasonal changes in body mass and energy metabolism in the Chaotung vole (Eothenomys olitor) and the physiological mechanisms underpinning these changes. Seasonal changes in the following parameters were measured in male E. olitor, body mass, food intake, thermogenesis, enzyme activity, masses of tissues and organs, hormone concentrations and expression of hypothalamic arcuate nucleus energy balance genes including neuropeptide Y (NPY), agouti-related protein (AgRP), pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART). Body mass was constant over the year, but the masses of tissues and organs differed significantly between seasons. There were significant changes in body fat mass and serum leptin levels over the four seasons. E. olitor showed significant seasonal changes in food intake and thermogenesis, uncoupling protein 1 (UCP1) content, enzyme activity, and serum tri-iodothyronine (T3) and thyroxine (T4) levels. Moreover, mRNA expression in the hypothalamus showed significant seasonal changes. All of our results suggested that E. olitor had constant body mass over the year, which was inconsistent with the prediction of the ‘set-point’ hypothesis. However, body fat mass and serum leptin levels were significantly different among the four seasons, providing support for the ‘set-point’ hypothesis. The changes in leptin, NPY, AgRP, POMC, and CART mRNA levels may play a role in the regulation of energy intake in E. olitor. Furthermore, the role of leptin and hypothalamic neuropeptide gene in the regulation of energy metabolism and body mass may be different in animals that are acclimated to different seasons.


      PubDate: 2015-03-01T17:06:29Z
       
  • Cardiorespiratory ontogeny and response to environmental hypoxia of larval
           spiny lobster, Sagmariasus verreauxi
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Quinn P. Fitzgibbon , Nicole Ruff , Stephen C. Battaglene
      Cardiorespiratory function is vital to an organism's ability to respond to environmental stress and analysis of cardiorespiratory capacity of species or life stages can elucidate vulnerability to climate change. Spiny lobsters have one of the most complex pelagic larval life cycles of any invertebrate and recently there has been an unexplained decline in post-larval recruitment for a number of species. We conducted the first analysis of the larval ontogeny of oxygen consumption, heart rate, maxilla 2 ventilation rate and oxyregulatory capacity of the spiny lobster, Sagmariasus verreauxi, to gain insight into their vulnerability to ocean change and to investigate life stage specific sensitivity to temperature-dependent oxygen limitation. In normoxia, heart and maxilla 2 ventilation rates increased in early larval development before declining, which we hypothesise is related to the transition from myogenic to neurogenic cardiac control. Maxilla 2 ventilation rate was sensitive to hypoxia at all larval stages, while heart rate was only sensitive to hypoxia in the late phyllosoma stages. Oxygen consumption conformed to environmental hypoxia at all larval stages. Spiny lobster larvae have limited respiratory control due to immature gas exchange physiology, compounded by their exceptionally large size. The lack of oxyregulatory ability suggests that all development stages are vulnerable to changes in sea temperature and oxygen availability. The synergetic stressors of increased temperature and reduced dissolved oxygen in the marine environment will diminish spiny lobster larval performance, increasing the challenge to achieve their extended larval life cycle, which may contribute to declines in post-larval recruitment.


      PubDate: 2015-03-01T17:06:29Z
       
  • Reversible brain swelling in crucian carp (Carassius carassius) and
           goldfish (Carassius auratus) in response to high external ammonia and
           anoxia
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Michael P. Wilkie , Jonathan A.W. Stecyk , Christine S. Couturier , Sanya Sidhu , Guro K. Sandvik , Göran E. Nilsson
      Increased internal ammonia (hyperammonemia) and ischemic/anoxic insults are known to result in a cascade of deleterious events that can culminate in potentially fatal brain swelling in mammals. It is less clear, however, if the brains of fishes respond to ammonia in a similar manner. The present study demonstrated that the crucian carp (Carassius carassius) was not only able to endure high environmental ammonia exposure (HEA; 2 to 22mmolL−1) but that they experienced 30% increases in brain water content at the highest ammonia concentrations. This swelling was accompanied by 4-fold increases in plasma total ammonia (TAmm) concentration, but both plasma TAmm and brain water content were restored to pre-exposure levels following depuration in ammonia-free water. The closely related, ammonia-tolerant goldfish (Carassius auratus) responded similarly to HEA (up to 3.6mmolL−1), which was accompanied by 4-fold increases in brain glutamine. Subsequent administration of the glutamine synthetase inhibitor, methionine sulfoximine (MSO), reduced brain glutamine accumulation by 80% during HEA. However, MSO failed to prevent ammonia-induced increases in brain water content suggesting that glutamine may not be directly involved in initiating ammonia-induced brain swelling in fishes. Although the mechanisms of brain swelling are likely different, exposure to anoxia for 96h caused similar, but lesser (10%) increases in brain water content in crucian carp. We conclude that brain swelling in some fishes may be a common response to increased internal ammonia or lower oxygen but further research is needed to deduce the underlying mechanisms behind such responses.


      PubDate: 2015-03-01T17:06:29Z
       
  • Interrelationship between feeding level and the metabolic hormones leptin,
           ghrelin and obestatin in control of chicken egg laying and release of
           ovarian hormones
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Alexander V. Sirotkin , Roland Grossmann
      The aim of the present experiment is to examine the role of nutritional status, metabolic hormones and their interrelationships in the control of chicken ovarian ovulatory and secretory activity. For this purpose, we identified the effect of food restriction, administration of leptin, ghrelin 1-18, obestatin and combinations of food restriction with these hormones for 3days on chicken ovulation (egg laying) rate and ovarian hormone release. The release of progesterone (P), testosterone (T), estradiol (E) and arginine-vasotocin (AVT) by isolated and cultured ovarian fragments was determined by EIA. It was observed that food restriction significantly reduced the egg-laying rate, T, E and AVT release and promoted P output by ovarian fragments. Leptin, administrated to ad libitum–fed chickens, did not change these parameters besides promoting E release. Nevertheless, administration of leptin was able to prevent the effect of food restriction on ovulation, T and E (but not P or AVT) release. Ghrelin 1-18 administration to ad libitum–fed birds did not affect the measured parameters besides a reduction in P release. Ghrelin 1-18 administration prevented the food restriction–induced decrease in ovarian T, E and AVT, but it did not change P output or egg laying. Obestatin administrated to control chicken promoted their ovarian P, E and inhibited ovarian AVT release but did not affect egg laying. It was able to promote the effect of food restriction on P, T and AVT, but not E release or egg laying. Our results (1) confirm an inhibitory effect of food restriction on chicken ovulation rate; (2) shows that food restriction–induced reduction in egg laying is associated with a decrease in ovarian T, E and AVT and an increase in ovarian P release; (3) confirm the involvement of metabolic hormones leptin, ghrelin and obestatin in the control of chicken ovarian hormones output; and (4) the ability of metabolic hormones to mimic/antagonize or prevent/promote the effects of food restriction on both egg laying and ovarian hormones demonstrates that nutritional status can influence ovarian ovulatory and endocrine functions via changes in metabolic hormones.


      PubDate: 2015-03-01T17:06:29Z
       
  • Nutritional and metabolic responses in common dentex (Dentex dentex) fed
           on different types and levels of carbohydrates
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Amalia Pérez-Jiménez , Emilia Abellán , Marta Arizcun , Gabriel Cardenete , Amalia E. Morales , M. Carmen Hidalgo
      The present study was aimed to evaluate the capacity of common dentex (Dentex dentex) to efficiently use dietary carbohydrates. So, the effects of different type and levels of carbohydrates on growth performance, feed utilization, fish composition, plasma metabolites and key metabolic pathways in liver and white muscle of common dentex are presented. Nine isonitrogenous (43%) and isoenergetic (22MJkg−1) diets were formulated combining three types, pregelatinized starch (PS), dextrin (Dx) and maltodextrin (Mx), and three levels (12, 18 and 24%) of carbohydrates. Growth performance was not significantly influenced by treatments. The best feed utilization was observed in 18% Mx group. Higher hepatic lipid content was found in fish fed lower dietary carbohydrate levels. PS induced higher liver and white muscle hexokinase and pyruvate kinase activities compared to the lower values observed for Mx. Malic enzyme and glucose 6-phosphate dehydrogenase in liver and white muscle were lower in Mx group. The influence of dietary carbohydrates source was more noticeable than those induced by the carbohydrate level, when glycolysis and lipogenesis pathways were considered. Common dentex is able to use properly dietary carbohydrates, although optimal dietary inclusion levels are below 24%. The greater protein-sparing effect was promoted by the less complex carbohydrate (maltodextrin) and the best feed utilization indices were obtained at intermediate levels of inclusion (18%).


      PubDate: 2015-03-01T17:06:29Z
       
  • Temperature acclimation of mitochondria function from the hearts of a
           temperate wrasse (Notolabrus celidotus)
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): F.I. Iftikar , A.J. Morash , D.G. Cook , N.A. Herbert , A.J.R. Hickey
      Understanding how mitochondrial function alters with acclimation may provide insight to the limits these organelles place on temperate fish hearts facing seasonal temperature fluctuations. This investigation determined if compromised cardiac mitochondrial function contributed to heart failure (HF) in the New Zealand wrasse Notolabrus celidotus acclimated at their mean summer and winter ocean temperatures. To test this hypothesis, fish were acclimated to cold (CA, 15°C) and warm (WA, 21°C) temperatures. The temperature of HF was determined by Doppler sonography and mitochondrial function in permeabilised cardiac fibres was tested using high resolution respirometry. Heat stress mediated HF occurred at a THF of 26.7±0.4°C for CA fish, and at 28.2±0.6°C for WA fish. Biochemical analyses also revealed that WA fish had elevated resting plasma lactate indicating an increased dependence on anaerobic pathways. When cardiac fibres were tested with increasing temperatures, apparent breakpoints in the respiratory control ratio (RCR-I) with substrates supporting complex I (CI) oxygen flux occurred below the THF for both acclimated groups. While WA cardiac mitochondria were less sensitive to increasing temperature for respirational flux supported by CI, Complex II, and chemically uncoupled flux, CA fish maintained higher RCRs at higher temperatures. We conclude that while acclimation to summer temperatures does alter cardiac mitochondrial function in N. celidotus, these changes need not be beneficial in terms of oxidative phosphorylation efficiency and may come at an energetic cost, which would be detrimental in the face of further habitat warming.


      PubDate: 2015-03-01T17:06:29Z
       
  • Does the right muscular atrioventricular valve in the avian heart perform
           two functions'
    • Abstract: Publication date: June 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 184
      Author(s): Valentina Prosheva , Bronislav Dernovoj , Sergey Kharin , Natalya Kaseva , Tatyana Shklyar , Felix Blyakhman
      The right atrioventricular valve of adult birds is a muscular unicuspid structure and unlike the right atrioventricular valve in the adult mammalian heart. The aim of this study is to test the hypothesis that the avian muscular valve (MV) is a part of the cardiac wall during systole and contributes to the right ventricle pump function. Six adult hens Gallus gallus domesticus were examined with a focus on MV structure and function. The thickness of the right ventricle (RV) wall and MV were examined post-mortem. RV wall and MV end-systolic thickness were estimated echocardiographically. The frame-by-frame processing of RV images was applied for the analysis of MV and RV free wall motion. According to the post-mortem measurements, no significant difference in the thickness between RV free wall and MV (1.8±0.3 and 1.6±0.4mm, respectively) was found. In the course of the entire cardiac cycle, MV demonstrated the excursion of 10.3±0.9mm. To the end of RV systole, MV thickness was increased roughly by a factor of two (2.9±0.57mm), and reached almost the same value (3.0±0.25mm) in RV free wall. Based on the findings obtained, we concluded that the MV may play specific and non-specific roles in the avian heart. First, MV determines the blood flow separation between the right heart chambers. Second, MV performs contractility to support for RV pump function.


      PubDate: 2015-03-01T17:06:29Z
       
 
 
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