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BIOCHEMISTRY (219 journals)                  1 2     

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African Journal of Biochemistry Research     Open Access   (Followers: 1)
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Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
American Journal of Biochemistry     Open Access   (Followers: 6)
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Asian Journal of Biochemistry     Open Access   (Followers: 1)
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Avicenna Journal of Medical Biochemistry     Open Access  
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Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 5)
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Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
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Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 5)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 4)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 6)
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Chemical and Biological Technologies for Agriculture     Open Access  
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Clinical Biochemistry     Hybrid Journal   (Followers: 19)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 60)
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Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
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Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 7)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
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Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 4)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 21)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 5)
DNA Barcodes     Open Access  
Doklady Biochemistry and Biophysics     Hybrid Journal   (Followers: 1)
Doklady Chemistry     Hybrid Journal  
Egyptian Journal of Biochemistry and Molecular Biology     Full-text available via subscription  
FABICIB     Open Access  
FEBS Letters     Hybrid Journal   (Followers: 58)
FEBS Open Bio     Open Access   (Followers: 3)
Fish Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Food & Function     Full-text available via subscription   (Followers: 5)
Foundations of Modern Biochemistry     Full-text available via subscription  
Free Radicals and Antioxidants     Full-text available via subscription   (Followers: 3)
Frontiers in Molecular Biosciences     Open Access   (Followers: 2)
Frontiers in Natural Product Chemistry     Hybrid Journal  
Global Biogeochemical Cycles     Full-text available via subscription   (Followers: 8)
Green Chemistry     Full-text available via subscription   (Followers: 9)
Histochemistry and Cell Biology     Hybrid Journal   (Followers: 4)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 3)
Indian Journal of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Indonesian Biomedical Journal     Open Access  
Insect Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3)
International Journal of Biochemistry & Cell Biology     Hybrid Journal   (Followers: 6)
International Journal of Biochemistry and Biophysics     Open Access  
International Journal of Biological Chemistry     Open Access   (Followers: 4)
International Journal of Food Contamination     Open Access  
International Journal of Plant Research     Open Access   (Followers: 3)
International Journal of Secondary Metabolite     Open Access   (Followers: 1)
Invertebrate Immunity     Open Access   (Followers: 1)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 4)
Journal of Microbial & Biochemical Technology     Open Access   (Followers: 1)
Journal of Applied Biology & Biotechnology     Open Access   (Followers: 1)
Journal of Bioactive and Compatible Polymers     Hybrid Journal   (Followers: 2)
Journal of Biochemistry     Hybrid Journal   (Followers: 41)
Journal of Biological Chemistry     Full-text available via subscription   (Followers: 161)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 9)
Journal of Carbohydrate Chemistry     Hybrid Journal   (Followers: 7)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Chemical Biology     Hybrid Journal   (Followers: 1)
Journal of Chemical Neuroanatomy     Hybrid Journal  
Journal of Clinical Lipidology     Hybrid Journal   (Followers: 1)
Journal of Comparative Physiology B : Biochemical, Systemic, and Environmental Physiology     Hybrid Journal   (Followers: 3)
Journal of Drug Discovery and Therapeutics     Open Access   (Followers: 1)
Journal of Enzyme Inhibition and Medicinal Chemistry     Hybrid Journal   (Followers: 4)
Journal of Evolutionary Biochemistry and Physiology     Hybrid Journal  
Journal of Food and Drug Analysis     Open Access  
Journal of Forensic Toxicology and Pharmacology     Hybrid Journal   (Followers: 3)
Journal of Inborn Errors of Metabolism and Screening     Open Access  
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Investigational Biochemistry     Open Access   (Followers: 2)
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Journal of Medical Biochemistry     Open Access   (Followers: 5)
Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
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Journal of Neurochemistry     Hybrid Journal   (Followers: 2)
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Journal of Pediatric Biochemistry     Hybrid Journal   (Followers: 1)
Journal of Peptide Science     Hybrid Journal   (Followers: 24)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 3)
Journal of Physiobiochemical Metabolism     Hybrid Journal   (Followers: 1)
Journal of Physiology and Biochemistry     Hybrid Journal   (Followers: 3)
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 5)
Journal of Steroid Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Journal of Virology & Antiviral Research     Hybrid Journal   (Followers: 2)
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 6)
La Rivista Italiana della Medicina di Laboratorio - Italian Journal of Laboratory Medicine     Hybrid Journal  
Marine Chemistry     Hybrid Journal   (Followers: 6)
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Molecular Informatics     Hybrid Journal   (Followers: 4)
Molecular inhibitors in targeted therapy     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
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Processes     Open Access  
Progress in Histochemistry and Cytochemistry     Hybrid Journal   (Followers: 1)

        1 2     

Journal Cover Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
  [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1095-6433
   Published by Elsevier Homepage  [2970 journals]
  • Remote bioenergetics measurements in wild fish: Opportunities and
    • Abstract: Publication date: Available online 6 April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Steven J. Cooke, Jacob W. Brownscombe, Graham D. Raby, Franziska Broell, Scott G. Hinch, Timothy D. Clark, Jayson M. Semmens
      The generalized energy budget for fish (i.e., Energy Consumed=Metabolism+Waste+Growth) is as relevant today as when it was first proposed decades ago and serves as a foundational concept in fish biology. Yet, generating accurate measurements of components of the bioenergetics equation in wild fish is a major challenge. How often does a fish eat and what does it consume' How much energy is expended on locomotion' How do human-induced stressors influence energy acquisition and expenditure' Generating answers to these questions is important to fisheries management and to our understanding of adaptation and evolutionary processes. The advent of electronic tags (transmitters and data loggers) has provided biologists with improved opportunities to understand bioenergetics in wild fish. Here, we review the growing diversity of electronic tags with a focus on sensor-equipped devices that are commercially available (e.g., heart rate/electrocardiogram, electromyogram, acceleration, image capture). Next, we discuss each component of the bioenergetics model, recognizing that most research to date has focused on quantifying the activity component of metabolism, and identify ways in which the other, less studied components (e.g., consumption, specific dynamic action component of metabolism, somatic growth, reproductive investment, waste) could be estimated remotely. We conclude with a critical but forward-looking appraisal of the opportunities and challenges in using existing and emerging electronic sensor-tags for the study of fish energetics in the wild. Electronic tagging has become a central and widespread tool in fish ecology and fisheries management; the growing and increasingly affordable toolbox of sensor tags will ensure this trend continues, which will lead to major advances in our understanding of fish biology over the coming decades.

      PubDate: 2016-04-08T23:58:01Z
  • Distribution and dynamics of branchial ionocytes in houndshark reared in
           full-strength and diluted seawater environments
    • Abstract: Publication date: Available online 31 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Souichirou Takabe, Mayu Inokuchi, Yoko Yamaguchi, Susumu Hyodo
      In teleost fishes, it is well-established that the gill serves as an important ionoregulatory organ in addition to its primary function of respiratory gas exchange. In elasmobranchs, however, the ionoregulatory function of the gills is still incompletely understood. Although two types of ionocytes, Na+/K+-ATPase (NKA)-rich (type-A) cell and vacuolar-type H+-ATPase (V-ATPase)-rich (type-B) cell, have been found in elasmobranch fishes, these cells were considered to function primarily in acid–base regulation. In the present study, we examined ion-transporting proteins expressed in ionocytes of Japanese-banded houndshark, Triakis scyllium, reared in full-strength seawater (SW) and transferred to diluted (30%) SW. In addition to the upregulation of NKA and Na+/H+ exchanger type 3 (NHE3) mRNAs in the type-A ionocytes, we found that Na+, Cl− cotransporter (NCC, Slc12a3) is expressed in a subpopulation of the type-B ionocytes, and that the expression level of NCC mRNA was enhanced in houndsharks transferred to a low-salinity environment. These results suggest that elasmobranch gill ionocytes contribute to NaCl uptake in addition to the already described function of acid–base regulation, and that NCC is most probably one of the key molecules for hyper-osmoregulatory function of elasmobranch gills. The existence of two types of ionocytes (NHE3- and NCC-expressing cells) that are responsible for NaCl absorption seems to be a common feature in both teleosts and elasmobranchs for adaptation to a low salinity environment. A possible driving mechanism for NCC in type-B ionocytes is discussed.

      PubDate: 2016-04-01T23:32:05Z
  • Roles of mechanistic target of rapamycin and transforming growth
           factor-β signaling in the molting gland (Y-organ) of the blackback
           land crab, Gecarcinus lateralis
    • Abstract: Publication date: Available online 31 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ali M. Abuhagr, Kyle S. MacLea, Megan R. Mudron, Sharon A. Chang, Ernest S. Chang, Donald L. Mykles
      Molting in decapod crustaceans is controlled by molt-inhibiting hormone (MIH), an eyestalk neuropeptide that suppresses production of ecdysteroids by a pair of molting glands (Y-organs or YOs). Eyestalk ablation (ESA) activates the YOs, which hypertrophy and increase ecdysteroid secretion. At mid premolt, which occurs 7–14days post-ESA, the YO transitions to the committed state; hemolymph ecdysteroid titers increase further and the animal reaches ecdysis ~3weeks post-ESA. Two conserved signaling pathways, mechanistic target of rapamycin (mTOR) and transforming growth factor-β (TGF-β), are expressed in the Gecarcinus lateralis YO. Rapamycin, an mTOR antagonist, inhibits YO ecdysteroidogenesis in vitro. In this study, rapamycin lowered hemolymph ecdysteroid titer in ESA G. lateralis in vivo; levels were significantly lower than in control animals at all intervals (1–14days post-ESA). Injection of SB431542, an activin TGF-β receptor antagonist, lowered hemolymph ecdysteroid titers 7 and 14days post-ESA, but had no effect on ecdysteroid titers at 1 and 3days post-ESA. mRNA levels of mTOR signaling genes Gl-mTOR, Gl-Akt, and Gl-S6k were increased by 3days post-ESA; the increases in Gl-mTOR and Gl-Akt mRNA levels were blocked by SB431542. Gl-elongation factor 2 and Gl-Rheb mRNA levels were not affected by ESA, but SB431542 lowered mRNA levels at Days 3 and 7 post-ESA. The mRNA level of an activin TGF-β peptide, Gl-myostatin-like factor (Mstn), increased 5.5-fold from 0 to 3days post-ESA, followed by a 50-fold decrease from 3 to 7days post-ESA. These data suggest that (1) YO activation involves an up regulation of the mTOR signaling pathway; (2) mTOR is required for YO commitment; and (3) a Mstn-like factor mediates the transition of the YO from the activated to the committed state.

      PubDate: 2016-04-01T23:32:05Z
  • Effects of ph and bicarbonate on mitochondrial functions of marine
    • Abstract: Publication date: Available online 1 April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Fouzia Haider, Halina Falfushynska, Anna V. Ivanina, Inna M. Sokolova
      Estuarine organisms including mollusks are exposed to periodic oxygen deficiency (hypoxia) that leads to a decrease in intracellular pH and accumulation of bicarbonate (HCO3 -). These changes can affect cellular bioenergetics; however, their effects on mitochondria of estuarine mollusks are not well understood. We determined the interactive effects of bicarbonate (0-10 mM) and pH (7.2 and 6.5) on mitochondrial oxygen consumption (ṀO2), membrane potential (Δψ) and production of reactive oxygen species (ROS) in two common estuarine bivalves - hard clams Mercenaria mercenaria, and bay scallops Argopecten irradians. In both species, elevated HCO3 - levels suppressed ADP-stimulated (state 3) ṀO2 but had little effect on the resting (state 4) respiration. These effects were not mediated by the soluble adenylyl cyclase or cyclic AMP. Effects of the low pH (6.5) on mitochondrial traits were species-specific and depended on the substrate oxidized by the mitochondria. Mild acidosis (pH 6.5) had minimal effects on ṀO2 and Δψ of the bivalve mitochondria oxidizing pyruvate but led to increased rates of ROS production in clams (ROS production could not be measured in scallops). In succinate-respiring mitochondria of clams, mild acidosis suppressed ṀO2 and increased mitochondrial coupling, while in scallop mitochondria the effects of low pH were opposite. Suppression of mitochondrial oxidative phosphorylation by bicarbonate and/or acidosis may contribute to the metabolic rate depression during shell closure or environmental hypoxia/hypercapnia. These findings have implications for understanding the physiological mechanisms involved in regulation of mitochondrial bioenergetics during hypoxia exposure in estuarine bivalves.

      PubDate: 2016-04-01T23:32:05Z
  • Effects of warm acclimation on physiology and gonad development in the sea
           urchin Evechinus chloroticus
    • Abstract: Publication date: Available online 1 April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Natalí J. Delorme, Mary A. Sewell
      The physiology of the New Zealand sea urchin Evechinus chloroticus was evaluated through feeding, respiration, growth and gonad growth in adult animals acclimated for 90days at 18°C (annual mean temperature) and 24°C (ambient summer temperature (21°C) +3°C). Measured parameters with representative rates of assimilation efficiency were used to calculate scope for growth (SfG) for each treatment. All physiological parameters were negatively affected at 24°C, showing a decrease in feeding rate which coincided with negative growth and gonad development at the end of the acclimation period, and a decrease in respiration rate suggesting metabolic depression. Histology of gonad samples after the acclimation period also showed no gametic material in animals acclimated at 24°C. All animals acclimated at 24°C had negative growth, differing from the calculated SfG which indicated that the animals had sufficient energy for production. The results suggest that calculated SfG in echinoderms should be used together with actual measurements of growth in individuals as, by itself, SfG may underestimate the actual effect of ocean warming when animals are exposed to stressful conditions. Overall, considering the total loss of reproductive output observed in E. chloroticus at higher temperatures, an increase in seawater temperature could dramatically influence the persistence of northern populations of this species, leading to flow-on effects in the subtidal ecosystem.

      PubDate: 2016-04-01T23:32:05Z
  • Using doubly-labelled water to measure free-living energy expenditure:
           Some old things to remember and some new things to consider
    • Abstract: Publication date: Available online 1 April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): John R. Speakman, Catherine Hambly
      The doubly-labelled water (DLW) method provides the ability to measure the energy expenditure of free-living animals based only on the injection of two isotopes in water (one of oxygen and one of hydrogen) and traditionally the collection of 2 blood samples. We review here the fundamental basis of how the method works, and highlight how the choice of the appropriate calculation equation can have a large impact on the resultant estimates, particularly in species where the difference between the isotope elimination constants is small. This knowledge is not new, but is worth reiterating given the potential for error by making the wrong choice. In particular, it is important to remember that for mammals weighing less than 5kg, and birds weighing less than 2kg, the single pool models perform best in validation studies, while in mammals above 15kg the two-pool models perform best. Above 2kg in birds and between 5 and 15kg in mammals, however, the model superiority is uncertain. Even where the choice based on body mass would appear clear, the decision may need to be tempered by species specific information regarding potential additional sources for hydrogen turnover, such as de novo lipogenesis or methanogenesis. Recent advances in the technique have included attempts to make the method less invasive by using innovative methods for dosing and sample collection. In addition, the advent of laser spectroscopy, as a replacement technology for mass spectrometry, may open up many new opportunities in the field. These potentially include direct sampling of breath in the field and tracking background isotope drift using 17oxygen levels.

      PubDate: 2016-04-01T23:32:05Z
  • Role of HIF-1 on phosphofructokinase and fructose 1, 6-bisphosphatase
           expression during hypoxia in the white shrimp Litopenaeus vannamei
    • Abstract: Publication date: Available online 29 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Keni Cota-Ruiz, Lilia Leyva-Carrillo, Alma B. Peregrino-Uriarte, Elisa M. Valenzuela-Soto, Teresa Gollas-Galván, Silvia Gómez-Jiménez, Jesús Hernández, Gloria Yepiz-Plascencia
      HIF-1 is a transcription factor that controls a widespread range of genes in metazoan organisms in response to hypoxia and is composed of α and β subunits. In shrimp, phosphofructokinase (PFK) and fructose bisphosphatase (FBP) are up-regulated in hypoxia. We hypothesized that HIF-1 is involved in the regulation of PFK and FBP genes in shrimp hepatopancreas under hypoxia. Long double stranded RNA (dsRNA) intramuscular injection was utilized to silence simultaneously both HIF-1 subunits, and then, we measured the relative expression of PFK and FBP, as well as their corresponding enzymatic activities in hypoxic shrimp hepatopancreas. The results indicated that HIF-1 participates in the up-regulation of PFK transcripts under short-term hypoxia since the induction caused by hypoxia (~1.6 and ~4.2-fold after 3 and 48h, respectively) is significantly reduced in the dsRNA animals treated. Moreover, PFK activity was significantly ~2.8-fold augmented after 3h in hypoxia alongside to an ~1.9-fold increment in lactate. However, when animals were dsRNA treated, both were significantly reduced. On the other hand, FBP transcripts were ~5.3-fold up-regulated in long-term hypoxic conditions (48h). HIF-1 is involved in this process since FBP transcripts were not induced by hypoxia when HIF-1 was silenced. Conversely, the FBP activity was not affected by hypoxia, which suggests its possible regulation at post-translational level. Taken together, these results position HIF-1 as a prime transcription factor in coordinating glucose metabolism through the PFK and FBP genes among others, in shrimp under low oxygen environments.

      PubDate: 2016-04-01T23:32:05Z
  • Rearing Mozambique tilapia in tidally-changing salinities: Effects on
           growth and the growth hormone/insulin-like growth factor I axis
    • Abstract: Publication date: Available online 23 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Benjamin P. Moorman, Yoko Yamaguchi, Darren T. Lerner, E. Gordon Grau, Andre P. Seale
      The growth hormone (GH)/insulin-like growth factor (IGF) axis plays a central role in the regulation of growth in teleosts and has been shown to be affected by acclimation salinity. This study was aimed at characterizing the effects of rearing tilapia, Oreochromis mossambicus, in a tidally-changing salinity on the GH/IGF axis and growth. Tilapia were raised in fresh water (FW), seawater (SW), or in a tidally-changing environment, in which salinity is switched between FW (TF) and SW (TS) every 6h, for 4months. Growth was measured over all time points recorded and fish reared in a tidally-changing environment grew significantly faster than other groups. The levels of circulating growth hormone (GH), insulin-like growth factor I (IGF-I), pituitary GH mRNA, gene expression of IGF-I, IGF-II, and growth hormone receptor 2 (GHR) in the muscle and liver were also determined. Plasma IGF-I was higher in FW and TS than in SW and TF tilapia. Pituitary GH mRNA was higher in TF and TS than in FW and SW tilapia. Gene expression of IGF-I in the liver and of GHR in both the muscle and liver changed between TF and TS fish. Fish growth was positively correlated with GH mRNA expression in the pituitary, and GHR mRNA expression in muscle and liver tissues. Our study indicates that rearing fish under tidally-changing salinities elicits a distinct pattern of endocrine regulation from that observed in fish reared in steady-state conditions, and may provide a new approach to increase tilapia growth rate and study the regulation of growth in euryhaline fish.

      PubDate: 2016-03-23T22:54:53Z
  • Temperature modulates testis steroidogenesis in European eel
    • Abstract: Publication date: Available online 21 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): David S. Peñaranda, Marina Morini, Helge Tveiten, M. Carmen Vílchez, Victor Gallego, Ron P. Dirks, Guido E.E.J.M. van den Thillart, Luz Pérez, Juan F. Asturiano
      This study evaluates the effects of temperature on hCG-induced spermatogenesis in European eel (Anguilla anguilla), subjected to three thermal regimes: T10: 10°C (first 4weeks), 15°C (next 3weeks) and 20°C (last 6weeks); T15: 15°C (first 4weeks) and 20°C (last 9weeks); and T20: constant 20°C for the duration of the experiment. At 10°C, maturation stopped in the A spermatogonial stage (SPG1), and no further maturation was observed until the temperature was ≥15°C. With the aim of explaining these results, the influence of temperature on steroidogenic enzyme gene expression and steroid synthesis was tested. The initial synthesis of androgens (T and 11-KT) increased at SPG1, and was not influenced by temperature. Likewise, the gene expression of the steroidogenic enzymes linked to androgen synthesis (aacyp11a1, aacyp17-I and aa11βHSD) also increased at SPG1. In contrast, no correlation was seen between the increase in E2 and the aacyp19a1 gene expression peak in the testes, with E2 increasing as a consequence of the seawater acclimation carried out before hormonal treatment, and peaking the aacyp19a1 gene expression at B spermatogonial stage (SPG2). Aacyp21 gene expression was also higher at SPG2, and this stage was only reached when the rearing temperature was ≥15°C. In conclusion, androgen synthesis is not dependent on temperature, but further maturation requires higher temperatures in order to induce a change in the steroidogenic pathway towards oestrogen and progestin synthesis. This study demonstrates that temperature plays a crucial role in European eel maturation, even perhaps controlling gonad development during the reproductive migration.

      PubDate: 2016-03-23T22:54:53Z
  • Daily rhythms of digestive enzyme activity and gene expression in gilthead
           seabream (Sparus aurata) during ontogeny
    • Abstract: Publication date: Available online 14 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): José Antonio Mata-Sotres, Francisco Javier Moyano, Gonzalo Martínez-Rodríguez, Manuel Yúfera
      In order to identify daily changes in digestive physiology in developing gilthead seabream larvae, the enzyme activity (trypsin, lipases and α–amylase) and gene expression (trypsinogen-try, chymotrypsinogen-ctrb, bile salt-activated lipase-cel1b, phospholipase A 2 -pla2 and α-amylase-amy2a) were measured during a 24hcycle in larvae reared under a 12h light/12h dark photoperiod. Larvae were sampled at 10, 18, 30 and 60days post hatch. In each sampling day, larvae were sampled every 3h during a complete 24hcycle. The enzyme activity and gene expression exhibited a marked dependent behavior to the light/darkness cycle in all tested ages. The patterns of activity and expression of all tested enzymes were compared to the feeding pattern found in the same larvae, which showed a rhythmic feeding pattern with a strong light synchronization. In the four tested ages, the activities of trypsin, and to a lesser extent lipases and amylase, were related to feeding activity. Molecular expression of the pancreatic enzymes tended to increase during the night, probably as an anticipation of the forthcoming ingestion of food that will take place during the next light period. It follows that the enzymatic activities are being regulated at translational and/or post-translational level. The potential variability of enzyme secretion along the whole day is an important factor to take into account in future studies. A particularly striking consequence of the present results is the reliability of studies based in only one daily sample taken at the same hour of the day, as those focused to assess ontogeny of digestive enzymes.

      PubDate: 2016-03-15T22:16:50Z
  • Assessing the reproducibility of fractional rates of protein synthesis in
           muscle tissue measured using the flooding dose technique
    • Abstract: Publication date: Available online 10 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ian D. McCarthy, James Brown
      The flooding dose technique of Garlick et al. (1980) has become the main method for measuring tissue and whole-animal rates of protein synthesis in ectotherms. However, single tissue samples are used to determine rates of protein synthesis and no studies have examined the pattern of flooding in large tissues such as the white muscle in fishes, which can comprise up to 55% of the wet body mass of a fish and which is poorly perfused. The present study has examined, for the first time, the patterns of flooding and measured rates of protein synthesis in five different regions of the white muscle in the Arctic charr Salvelinus alpinus ranging in size from 25g to 1.6kg following a flooding dose injection of L-3H-phenylalanine. The results indicate that the degree of flooding (i.e. free pool specific radioactivity relative to that of the injection solution) and elevation in free phenylalanine concentrations can vary between regions but the calculated fractional rates of protein synthesis were similar in four of the five regions studied. The variability in rates of protein synthesis increased with body size with greater variability observed between regions for fish >1kg in body mass. For consistency between studies, it is recommended that samples are taken from the epaxial muscle in the region below the dorsal fin when measuring fractional rates of white muscle synthesis in fishes.

      PubDate: 2016-03-10T21:46:31Z
  • Editorial Board
    • Abstract: Publication date: May 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 195

      PubDate: 2016-03-10T21:46:31Z
  • Melatonin not only restores but also prevents the inhibition of the
           intestinal Ca2+ absorption caused by glutathione depleting drugs
    • Abstract: Publication date: Available online 9 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Vanessa Areco, Valeria Rodriguez, Ana Marchionatti, Agata Carpentieri, Nori Tolosa de Talamoni
      We have previously demonstrated that melatonin (MEL) blocks the inhibition of the intestinal Ca2+ absorption caused by menadione (MEN). The purpose of this study were to determine whether MEL not only restores but also prevents the intestinal Ca2+ absorption inhibited either by MEN or BSO, two drugs that deplete glutathione (GSH) in different ways, and to analyze the mechanisms by which MEN and MEL alter the movement of Ca2+ across the duodenum. To know this, chicks were divided into four groups: 1) controls, 2) MEN treated, 3) MEL treated, and 4) treated sequentially with MEN and MEL or with MEN and MEL at the same time. In a set of experiments, chicks treated with BSO or sequentially with BSO and MEL or with BSO and MEL at the same time were used. MEL not only restored but also prevented the inhibition of the chick intestinal Ca2+ absorption produced by either MEN or BSO. MEN altered the protein expression of molecules involved in the transcellular as well as in the paracellular pathway of the intestinal Ca2+ absorption. MEL restored partially both pathways through normalization of the O2 − levels. The nitrergic system was not altered by any treatment. In conclusion, MEL prevents or restores the inhibition of the intestinal Ca2+ absorption caused by different GSH depleting drugs. It might become one drug for the treatment of intestinal Ca2+ absorption under oxidant conditions having the advantage of low or null side effects.

      PubDate: 2016-03-10T21:46:31Z
  • Estimating the critical thermal maximum (CTmax) of bed bugs, Cimex
           lectularius: Comparing thermolimit respirometry with traditional visual
    • Abstract: Publication date: Available online 9 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Zachary C. DeVries, Stephen A. Kells, Arthur G. Appel
      Evaluating the critical thermal maximum (CT max) in insects has provided a number of challenges. Visual observations of endpoints (onset of spasms, loss of righting response, etc.) can be difficult to measure consistently, especially with smaller insects. To resolve this problem, Lighton and Turner (2004) developed a new technique: thermolimit respirometry (TLR). TLR combines real time measurements of both metabolism (V̇CO2) and activity to provide two independent, objective measures of CT max. However, several questions still remain regarding the precision of TLR and how accurate it is in relation to traditional methods. Therefore, we evaluated CT max of bed bugs using both traditional (visual) methods and TLR at three important metabolic periods following feeding (1 d, 9 d, and 21 d). Both methods provided similar estimates of CT max, although traditional methods produced consistently lower values (0.7–1°C lower than TLR). Despite similar levels of precision, TLR provided a more complete profile of thermal tolerance, describing changes in metabolism and activity leading up to the CT max, not available through traditional methods. In addition, feeding status had a significant effect on bed bug CT max, with bed bugs starved 9 d (45.19[±0.20]°C) having the greatest thermal tolerance, followed by bed bugs starved 1 d (44.64[±0.28]°C), and finally bed bugs starved 21 d (44.12[±0.28]°C). Accuracy of traditional visual methods in relation to TLR is highly dependent on the selected endpoint; however, when performed correctly, both methods provide precise, accurate, and reliable estimations of CT max .

      PubDate: 2016-03-10T21:46:31Z
  • Dopamine inhibits somatolactin Gene Expression in tilapia pituitary cells
           through the dopamine D2 receptors
    • Abstract: Publication date: Available online 10 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Quan Jiang, Anji Lian, Qi He
      Dopamine (DA) is an important neurotransmitter in the central nervous system of vertebrates and possesses key hypophysiotropic functions. Early studies have shown that DA has a potent inhibitory effect on somatolactin (SL) release in fish. However, the mechanisms responsible for DA inhibition of SL gene expression are largely unknown. To this end, tilapia DA type-1 (D1) and type-2 (D2) receptor transcripts were examined in the neurointermediate lobe (NIL) of the tilapia pituitary by real-time PCR. In tilapia, DA not only was effective in inhibiting SL mRNA levels in vivo and in vitro, but also could abolish pituitary adenylate cyclase-activating polypeptide (PACAP)- and salmon gonadotropin-releasing hormone (sGnRH)-stimulated SL gene expression at the pituitary level. In parallel studies, the specific D2 receptor agonists quinpirole and bromocryptine could mimic the DA-inhibited SL gene expression. Furthermore, the D2 receptor antagonists domperidone and (−)-sulpiride could abolish the SL response to DA or the D2 agonist quinpirole, whereas D1 receptor antagonists SCH23390 and SKF83566 were not effective in this respect. In primary cultures of tilapia NIL cells, D2 agonist quinpirole-inhibited cAMP production could be blocked by co-treatment with the D2 antagonist domperidone and the ability of forskolin to increase cAMP production was also inhibited by quinpirole. Using a pharmacological approach, the AC/cAMP pathway was shown to be involved in quinpirole-inhibited SL mRNA expression. These results provide evidence that DA can directly inhibit SL gene expression at the tilapia pituitary level via D2 receptor through the AC/cAMP-dependent mechanism.

      PubDate: 2016-03-10T21:46:31Z
  • Infrared thermography: A non-invasive window into thermal physiology
    • Abstract: Publication date: Available online 2 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Glenn J. Tattersall
      Infrared thermography is a non-invasive technique that measures mid to long-wave infrared radiation emanating from all objects and converts this to temperature. As an imaging technique, the value of modern infrared thermography is its ability to produce a digitized image or high speed video rendering a thermal map of the scene in false colour. Since temperature is an important environmental parameter influencing animal physiology and metabolic heat production an energetically expensive process, measuring temperature and energy exchange in animals is critical to understanding physiology, especially under field conditions. As a non-contact approach, infrared thermography provides a non-invasive complement to physiological data gathering. One caveat, however, is that only surface temperatures are measured, which guides much research to those thermal events occurring at the skin and insulating regions of the body. As an imaging technique, infrared thermal imaging is also subject to certain uncertainties that require physical modelling, which is typically done via built-in software approaches. Infrared thermal imaging has enabled different insights into the comparative physiology of phenomena ranging from thermogenesis, peripheral blood flow adjustments, evaporative cooling, and to respiratory physiology. In this review, I provide background and guidelines for the use of thermal imaging, primarily aimed at field physiologists and biologists interested in thermal biology. I also discuss some of the better known approaches and discoveries revealed from using thermal imaging with the objective of encouraging more quantitative assessment.

      PubDate: 2016-03-05T21:40:46Z
  • Identification of a heat shock protein 90 gene involved in resistance to
           temperature stress in two wing-morphs of Nilaparvata lugens (Stål)
    • Abstract: Publication date: Available online 3 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kai Lu, Xia Chen, Wenting Liu, Qiang Zhou
      The brown planthopper, Nilaparvata lugens, is one of the most destructive pests damaging rice in Asia and exhibits wing dimorphism, with brachypters possessing severely reduced wings and macropters bearing fully developed wings. Previous studies have shown that macropters are more heat resistant than brachypters. To understand the molecular mechanism underlying the differential thermotolerance abilities of these two morphs, a full-length Hsp gene, NlHsp90 was cloned from N. lugen. Our results showed that the relative expression levels of NlHsp90 in N. lugens females increased with the rise of temperature. Interestingly, NlHsp90 in macropters females could be induced at lower temperature (32°C) than that in brachypters (34°C), and the NlHsp90 mRNA levels in macropters were significantly higher than those in brachypters from 34 to 40°C. In addition, the maximum expression levels of NlHsp90 were achieved much earlier in macropters, and NlHsp90 mRNA levels in macropters were significantly higher than those in brachypters from 1 to 6h of recovery after temperature stress. Furthermore, knockdown of NlHsp90 by dsRNA injection reduced survival in both morphs with a greater reduction in the macropters relative to that of the brachyters. These results indicated that NlHsp90 plays an important role for thermotolerance in N. lugens, and there is difference on induction between two morphs.

      PubDate: 2016-03-05T21:40:46Z
  • Thermal acclimation to cold alters myosin content and contractile
           properties of rainbow smelt, Osmerus mordax, red muscle
    • Abstract: Publication date: Available online 3 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): David J. Coughlin, Lisa P. Shiels, Seshuvardhan Nuthakki, Jacie L. Shuman
      Rainbow smelt (Osmerus mordax), a eurythermal fish, live in environments from −1.8 to 20°C, with some populations facing substantial annual variation in environmental temperature. These different temperature regimes pose distinct challenges to locomotion by smelt. Steady swimming performance, red muscle function and muscle myosin content were examined to assess the prediction that cold acclimation by smelt will lead to improved steady swimming performance and that any performance shift will be associated with changes in red muscle function and in its myosin heavy chain composition. Cold acclimated (4°C) smelt had a faster maximum steady swimming speed and swam with a higher tailbeat frequency than warm acclimated (10°C) smelt when tested at the same temperature (10°C). Muscle mechanics experiments demonstrated faster contractile properties in the cold acclimated fish when tested at 10°C. The red muscle of cold acclimated smelt had a shorter twitch times, a shorter relaxation times and a higher maximum shortening velocity. In addition, red muscle from cold acclimated fish displayed reduced thermal sensitivity to cold, maintaining higher force levels at 4°C compared to red muscle from warm acclimated fish. Immunohistochemistry suggests shifts in muscle myosin composition and a decrease in muscle cross-sectional area with cold acclimation. Dot blot analysis confirmed a shift in myosin content. Rainbow smelt do show a significant thermal acclimation response to cold. An examination of published values of maximum muscle shortening velocity in fishes suggests that smelt are particularly well suited to high levels of activity in very cold water.

      PubDate: 2016-03-05T21:40:46Z
  • Physiological constraints scale with body mass during dives in auks: A
           comparative analysis
    • Abstract: Publication date: Available online 4 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): A. Shoji, S. Aris-Brosou, K.H. Elliot
      Many behavioral processes scale with body mass (M) because underlying physiological constraints, such as metabolism, scale with M. A classic example is the maximum duration of dives by breath-hold divers, which scales with M 0.25, as predicted from the ratio of oxygen stores (M 1.0) to diving oxygen consumption rate (M 0.75) — assuming classic scaling relationships for those physiological processes. However, maximum dive duration in some groups of birds does not have a 0.25 scaling exponent. We re-examined the allometric scaling of maximum dive duration in auks to test whether the discrepancy was due to poor data (earlier analyses included data from many different sources possibly leading to bias), phylogeny (earlier analyses did not account for phylogenetic inertia) or physiology (earlier analyses did not analyze physiological parameters alongside behavioral parameters). When we included only data derived from electronic recorders and after accounting for phylogeny, the equation for maximum dive duration was proportional to M 0.33. At the same time, myoglobin concentration in small breath-hold divers was proportional to M 0.36, implying that muscle oxygen stores were proportional to M 1.36, but diving oxygen consumption rate in wing-propelled divers was only proportional to M 0.79. Thus, the 99% confidence interval included the exponent of 0.57 predicted from the observed relationships between oxygen stores and consumption rates. In conclusion, auks are not exceptions to the hypothesis that a trade-off between oxygen stores and oxygen utilization drives variation in maximum dive duration. Rather, the scaling exponent for maximum dive duration is higher than expected due to the higher than expected scaling of muscle oxygen stores to body mass.

      PubDate: 2016-03-05T21:40:46Z
  • Thermal impacts on the growth, development and ontogeny of critical
           swimming speed in Atlantic herring larvae
    • Abstract: Publication date: Available online 3 March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Marta Moyano, Björn Illing, Philip Peschutter, Klaus B. Huebert, Myron A. Peck
      Increases in swimming ability have a profound influence on larval fish growth and survival by increasing foraging success, predator avoidance and the ability to favorably influence transport. Understanding how development and environmental factors combine to influence swimming performance in aquatic organisms is particularly important during the transition from viscous to inertial environments. We measured the growth, development and ontogenetic changes in critical swimming speed (U crit ) in Atlantic herring (Clupea harengus) larvae reared at three temperatures (7, 11, 15°C). Temperature had a significant effect on growth rates (from 0.21 at 7°C to 0.34mm·d−1 at 15°C), and larval morphology-at-length (increased dry weight (DW), body height and developmental rate at warmer temperatures). Temperature-dependent differences in morphology influenced swimming performance (e.g. the exponential increase in U crit with increasing body size was faster at warmer temperatures). Larvae entered the transition to an inertial environment (Reynolds numbers ≥300) at body lengths between 15 (15°C) and 17mm (7°C). Inter-individual differences in U crit were not related to nutritional condition (RNA·DNA −1 or DNA·DW −1), but were negatively correlated to length-at-age, suggesting a trade-off between growth rate and locomotor activity. The U crit data from this and previously published studies suggest that Atlantic herring pass through four activity phases: 1) yolk-sac (<0.6cm·s−1), 2) pre-flexion (0.6–3.0cm·s−1, temperature effect changes with body size), 3) post-flexion (up to 6–8cm·s−1, Q 10 ~1.8–2.0), 4) juvenile–adult period (20–170cm·s−1).

      PubDate: 2016-03-05T21:40:46Z
  • Seawater acidification affects the physiological energetics and spawning
           capacity of the Manila clam Ruditapes philippinarum during gonadal
    • Abstract: Publication date: Available online 26 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Xian Xu, Feng Yang, Liqiang Zhao, Xiwu Yan
      Ocean acidification is predicted to have widespread implications for marine bivalve mollusks. While our understanding of its impact on their physiological and behavioral responses is increasing, little is known about their reproductive responses under future scenarios of anthropogenic climate change. In this study, we examined the physiological energetics of the Manila clam Ruditapes philippinarum exposed to CO2-induced seawater acidification during gonadal maturation. Three recirculating systems filled with 600 L of seawater were manipulated to three pH levels (8.0, 7.7, and 7.4) corresponding to control and projected pH levels for 2100 and 2300. In each system, temperature was gradually increased ca. 0.3°C per day from 10 to 20°C for 30days and maintained at 20°C for the following 40days. Irrespective of seawater pH levels, clearance rate (CR), respiration rate (RR), ammonia excretion rate (ER), and scope for growth (SFG) increased after a 30-day stepwise warming protocol. When seawater pH was reduced, CR, ratio of oxygen to nitrogen, and SFG significantly decreased concurrently, whereas ammonia ER increased. RR was virtually unaffected under acidified conditions. Neither temperature nor acidification showed a significant effect on food absorption efficiency. Our findings indicate that energy is allocated away from reproduction under reduced seawater pH, potentially resulting in an impaired or suppressed reproductive function. This interpretation is based on the fact that spawning was induced in only 56% of the clams grown at pH 7.4. Seawater acidification can therefore potentially impair the physiological energetics and spawning capacity of R. philippinarum.

      PubDate: 2016-02-29T21:17:16Z
  • Endocrine consequences of an acute stress under different thermal
           conditions: A study of corticosterone, prolactin, and thyroid hormones in
           the pigeon (Columbia livia)
    • Abstract: Publication date: Available online 24 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Frédéric Angelier, Charline Parenteau, Stéphanie Ruault, Nicole Angelier
      In the context of global change, the physiological and hormonal stress responses have received much attention because of their implications in terms of allostasis. However, most studies have focused on glucocorticoids only as the “common” response to stressors while neglecting other endocrine axes and hormones (e.g. prolactin, thyroid hormones) that play a crucial role in metabolic adjustments. Interestingly, the responsiveness of all these endocrine axes to stress may depend on the energetic context and this context-dependent stress response has been overlooked so far. In the wild, temperature can vary to a large extent within a short time window and ambient temperature may affect these metabolic-related endocrine axes, and potentially, their responsiveness to an acute stressor. Here, we explicitly tested this hypothesis by examining the effect of a standardized stress protocol on multiple hormonal responses in the rock pigeon (Columbia livia). We tested the effect of an acute restraint stress on (1) corticosterone levels, (2) prolactin levels, and (3) thyroid hormone levels (triiodothyronine, thyroxine) in pigeons that were held either at cool temperature (experimental birds) or at room temperature (control birds) during the stress protocol. Although we found a significant influence of restraint stress on most hormone levels (corticosterone, prolactin, and thyroxine), triiodothyronine levels were not affected by the restraint stress. This demonstrates that stressors can have significant impact on multiple endocrine mechanisms. Importantly, all of these hormonal responses to stress were not affected by temperature, demonstrating that the exposure to cold temperature does not affect the way these hormone levels change in response to handling stress. This suggests that some endocrine responses to temperature decreases may be overridden by the endocrine responses to an acute restraint stress.

      PubDate: 2016-02-24T20:44:35Z
  • Regional variation of gene regulation associated with storage lipid
           metabolism in American glass eels (Anguilla rostrata)
    • Abstract: Publication date: Available online 24 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mélanie Gaillard, Scott A. Pavey, Caroline L. Côté, Réjean Tremblay, Louis Bernatchez, Céline Audet
      Variation in gene regulation may be involved in the differences observed for life history traits within species. American eel (Anguilla rostrata ) is well known to harbour distinct ecotypes within a single panmictic population. We examined the expression of genes involved in the regulation of appetite as well as lipid and glycogen among glass eels migrating to different locations on the Canadian east coast and captured at two different periods of upstream migration. Gene expression levels of three reference and five candidate genes were analyzed by real-time PCR with Taqman probes in recently captured wild glass eels. All gene transcripts were detected in glass eels. Of the five candidate genes, bile salt activated and triacylglycerol lipases were respectively 7.65 and 3.25 times more expressed in glass eels from the St. Lawrence estuary than in those from Nova Scotia, and there was no effect related to the two-week difference in capture date. These two genes explained 82.41% of the dissimilarity between the two rivers. In contrast, glycogen phosphorylase, ghrelin, and leptin receptor genes showed no significant differences in gene transcription. These results confirmed at the molecular level an observation that was recently made at the phenotypic level: that glass eels from the St. Lawrence estuary have a greater capacity to use lipid reserves to sustain their metabolic needs. These observations add to the body of evidence supporting the hypothesis that regional phenotypic variation observed in American eel is determined early in life and that part of this variation is likely under genetic control. Keywords ecotypes, ghrelin, glycogen phosphorylase, leptin receptor, lipase, mRNA expression, transcriptomics

      PubDate: 2016-02-24T20:44:35Z
  • Gonadotropin and sf-1 regulation of cyp19a1a gene and aromatase activity
           during oocyte development in the rohu, L. rohita
    • Abstract: Publication date: Available online 23 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sujata Roy Moulik, Puja Pal, Suravi Majumder, Buddhadev Mallick, Shreyasi Gupta, Payel Guha, Sibsankar Roy, Dilip Mukherjee
      Cytochrome P450 aromatase (P450arom), a product of cyp19a1 gene, plays pivotal roles in vertebrate steroidogenesis and reproduction. In this study, we isolated partial cDNA encoding the ovarian (cyp19a1a) and brain (cyp19a1b) P450arom genes from adult female rohu, Labeo rohita and investigated the regulation of cyp19a1a by gonadotropin and SF-1. The cyp19a1a and cyp19a1b were expressed predominantly in the ovary and brain respectively, with quantity of the former attuned to reproductive cycle. To elucidate gonadotropin regulation of cyp19a1a mRNA expression and P450 aromatase activity for 17β-estradiol (E2) biosynthesis in vitro by the vitellogenic ovarian follicles, time- and dose-dependent studies were conducted with HCG and porcine FSH. Results demonstrated that HCG stimulated significantly higher expression of cyp19a1a mRNA and aromatase activity leading to increased biosynthesis of E2 than FSH. To understand the involvement of SF-1 to in the regulation of cyp19a1a and aromatase activity, ovarian follicles were incubated with increasing concentrations of HCG and expression of sf1gene and activation of SF-1 protein were measured. Results demonstrated that HCG significantly induced expression of sf1gene and activation of SF-1 protein suggesting a link between SF-1 and P450 aromatase activation in this fish ovary during gonadotropin-induced steroidogenesis.

      PubDate: 2016-02-24T20:44:35Z
  • Editorial Board
    • Abstract: Publication date: April 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 194

      PubDate: 2016-02-16T20:17:55Z
  • Local adaptation to osmotic environment in killifish, Fundulus
           heteroclitus, is supported by divergence in swimming performance but not
           by differences in excess post-exercise oxygen consumption or aerobic scope
    • Abstract: Publication date: Available online 12 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Reid S. Brennan, Ruth Hwang, Michelle Tse, Nann Fangue, Andrew Whitehead
      Regulation of internal ion homeostasis is essential for fishes inhabiting environments where salinities differ from their internal concentrations. It is hypothesized that selection will act to reduce energetic costs of osmoregulation in a population's native osmotic habitat, producing patterns of local adaptation. Killifish, Fundulus heteroclitus, occupy estuarine habitats where salinities range from fresh water to seawater. Populations inhabiting an environmental salinity gradient differ in physiological traits associated with acclimation to acute salinity stress, consistent with local adaptation. Similarly, metabolic rates differ in populations adapted to different temperatures, but have not been studied in regard to salinity. We investigated evidence for local adaptation between populations of killifish native to fresh and brackish water habitats. Aerobic scope (the difference between minimum and maximum metabolic rates), excess post-exercise oxygen consumption, and swimming performance (time and distance to reach exhaustion) were used as proxies for fitness in fresh and brackish water treatments. Swimming performance results supported local adaptation; fish native to brackish water habitats performed significantly better than fresh water-native fish at high salinity while low salinity performance was similar between populations. However, results from metabolic measures did not support this conclusion; both populations showed an increase in resting metabolic rate and a decrease of aerobic scope in fresh water. Similarly, excess post-exercise oxygen consumption was higher for both populations in fresh than in brackish water. While swimming results suggest that environmentally dependent performance differences may be a result of selection in divergent osmotic environments, the differences between populations are not coupled with divergence in metabolic performance.

      PubDate: 2016-02-16T20:17:55Z
  • Osmoregulation in larvae and juveniles of two recently separated
           Macrobrachium species: Expression patterns of ion transporter genes
    • Abstract: Publication date: Available online 9 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Nesrine Boudour-Boucheker, Viviane Boulo, Mireille Charmantier-Daures, Klaus Anger, Guy Charmantier, Catherine Lorin-Nebel
      In this comparative study, osmoregulatory mechanisms were analyzed in two closely related species of palaemonid shrimp from Brazil, Macrobrachium pantanalense and M. amazonicum. A previous investigation showed that all postembryonic stages of M. pantanalense from inland waters of the Pantanal are able to hyper-osmoregulate in fresh water, while this species was not able to hypo-osmoregulate at high salinities. In M. amazonicum originating from the Amazon estuary, in contrast, all stages are able to hypo-osmoregulate, but only first-stage larvae, late juveniles and adults are able to hyper-osmoregulate in fresh water. The underlying molecular mechanisms of these physiological differences have not been known. We therefore investigated the expression patterns of three ion transporters (NKA α-subunit, VHA B-subunit and NHE3) following differential salinity acclimation in different ontogenetic stages (stage-V larvae, juveniles) of both species. Larval NKAα expression was at both salinities significantly higher in M. pantanalense than in M. amazonicum, whereas no difference was noted in juveniles. VHA was also more expressed in larvae of M. pantanalense than in those of M. amazonicum. When NHE3 expression is compared between the larvae of the two species, further salinity-related differences were observed, with generally higher expression in the inland species. Overall, a high expression of ion pumps in M. pantanalense suggests an evolutionary key role of these transporters in freshwater invasion.

      PubDate: 2016-02-11T20:07:06Z
  • Morphological and metabolic adjustments in the small intestine to energy
           demands of growth, storage, and fasting in the first annual cycle of a
           hibernating lizard (Tupinambis merianae)
    • Abstract: Publication date: Available online 9 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lucas Francisco R. do Nascimento, Lilian Cristina da Silveira, Laura Gabriela Nisembaum, Alison Colquhoun, Agusto S. Abe, Carlos Alberto Mandarim-de-Lacerda, Silvia Cristina R. de Souza
      Seasonal plasticity in the small intestine of neonatal tegu lizards was investigated using morphometry and analysis of enzymes involved in supplying energy to the intestinal tissue. In the autumn, the intestinal mass (Mi) was 1.0% of body mass and the scaling exponent b =0.92 indicated that Mi was larger in smaller neonates. During arousal from dormancy Mi was 23% smaller; later in spring, Mi increased 60% in relation to the autumn and the exponent b =0.14 indicated that the recovery was disproportionate in smaller tegus. During the autumn the intestinal villi were greatly elongated; by midwinter, the Hv, SvEp, and VvEp were smaller than during the autumn (59%, 54%, 29%) and were restored to autumn levels during spring. In the active tegus, the maximum activity (Vmax) of enzymes indicated that the enterocytes can obtain energy from different sources, and possess gluconeogenic capacity. During winter, the Vmax of CS, HOAD, GDH, PEPCK was 40–50% lower in relation to the autumn and spring, while the Vmax of HK, PK, LDH, AST was unchanged. The hypoglycemia and the mucosal atrophy/ischemia during winter would prevent the enterocytes from using glucose, whereas they could slowly oxidize fatty acids released from body stores and amino acids from the tissue proteolysis to satisfy their needs of energy. Contrastingly, starvation during spring caused severe mass loss (50%); the tissue protein and the VvEp and VvLP did not change while the thickness of the muscular layer increased 51%, which suggested different effects along the length of the organ. In addition, the Vmax of the glycolytic enzymes were lower, indicating that a regulatory mechanism would spare blood glucose for vital organs during unanticipated food restriction.

      PubDate: 2016-02-11T20:07:06Z
  • Low-intensity pulsed ultrasound induces apoptosis in osteoclasts: Fish
           scales are a suitable model for the analysis of bone metabolism by
    • Abstract: Publication date: Available online 2 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Nobuo Suzuki, Taizo Hanmoto, Sachiko Yano, Yukihiro Furusawa, Mika Ikegame, Yoshiaki Tabuchi, Takashi Kondo, Kei-ichiro Kitamura, Masato Endo, Toshio Yamamoto, Toshio Sekiguchi, Makoto Urata, Yuko Mikuni-Takagaki, Atsuhiko Hattori
      Using fish scales in which osteoclasts and osteoblasts coexist on the calcified bone matrix, we examined the effects of low-intensity pulsed ultrasound (LIPUS) on both osteoclasts and osteoblasts. At 3h of incubation after LIPUS treatment, osteoclastic markers such as tartrate-resistant acid phosphatase (TRAP) and cathepsin K mRNA expressions decreased significantly while mRNA expressions of osteoblastic markers, osteocalcin, distal-less homeobox 5, runt-related transcription factor 2a, and runt-related transcription factor 2b, increased significantly. At 6 and 18h of incubation, however, both osteoclastic and osteoblastic marker mRNA expression did not change at least present conditions. Using GeneChip analysis of zebrafish scales treated with LIPUS, we found that cell death-related genes were upregulated with LIPUS treatment. Real-time PCR analysis indicated that the expression of apoptosis-related genes also increased significantly. To confirm the involvement of apoptosis in osteoclasts with LIPUS, osteoclasts were induced by autotransplanting scales in goldfish. Thereafter, the DNA fragmentation associated with apoptosis was detected in osteoclasts using the TUNEL (TdT-mediated dUTP nick-end labeling) method. The multi-nuclei of TRAP-stained osteoclasts in the scales were labeled with TUNEL. TUNEL staining showed that the number of apoptotic osteoclasts in goldfish scales was significantly elevated by treatment with LIPUS at 3h of incubation. Thus, we are the first to demonstrate that LIPUS directly functions to osteoclasts and to conclude that LIPUS directly causes apoptosis in osteoclasts shortly after exposure.

      PubDate: 2016-02-11T20:07:06Z
  • Ammonia excretion in Caenorhabditis elegans: Physiological and molecular
           characterization of the rhr-2 knock-out mutant
    • Abstract: Publication date: Available online 9 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Aida Adlimoghaddam, Michael J. O'Donnell, Jay Kormish, Sheena Banh, Jason R. Treberg, David Merz, Dirk Weihrauch
      Previous studies have shown the free living soil nematode Caenorhabditis elegans (N2 strain) to be ammonotelic. Ammonia excretion was suggested to take place partially via the hypodermis, involving the Na+/K+-ATPase (NKA), V-ATPase (VAT), carbonic anhydrase, NHX-3 and a functional microtubule network and at least one Rh-like ammonia transporter RHR-1. In the current study we show that a second Rh-protein, RHR-2, is highly expressed in the hypodermis, here also in the apical membrane of that tissue. To further characterize the role of RHR-2 in ammonia excretion, a knock-out mutant rhr-2(ok403), further referred to as ∆ rhr-2, was employed. Compared to wild-type worms (N2), this mutant showed a lower rate of ammonia excretion and a lower hypodermal H+ excretion rate. At the same time rhr-1, nka, vat, and nhx-3 showed higher mRNA expression levels when compared to N2. Also, in contrast to N2 worms, ∆ rhr-2 did not show enhanced ammonia excretion rates when exposed to a low pH environment, suggesting that RHR-2 represents the apical NH3 pathway that allows ammonia trapping via the hypodermis in N2 worms. A hypothetical model for the mechanism of hypodermal ammonia excretion is proposed on the basis of data in this and previous investigations.

      PubDate: 2016-02-11T20:07:06Z
  • Editorial Board
    • Abstract: Publication date: March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 193

      PubDate: 2016-02-11T20:07:06Z
  • Adrenocortical function in cane toads from different environments
    • Abstract: Publication date: Available online 11 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sandra E. Hernández, Conrad Sernia, Adrian J. Bradley
      The adrenocortical function of cane toads (Rhinella marina) exposed to different experimental procedures, as well as captured from different environments, was assessed by challenging the hypothalamic–pituitary-adrenal (HPA) axis. It was found that that restriction stress as well as cannulation increased plasma corticosterone (B) levels for up to 12h. A single dose of dexamethasone (DEX 2mg/kg) significantly reduced B levels demonstrating its potential for use in the evaluation of the HPA axis in amphibia. We also demonstrate that 0.05IU/g BW (im) of synthetic adrenocorticotropic hormone (ACTH) significantly increased plasma B levels in cane toads. Changes in size area of the cortical cells were positively associated with total levels of B after ACTH administration. We also found differences in adrenal activity between populations. This was assessed by a DEX-ACTH test. The animals captured from the field and maintained in captivity for one year at the animal house (AH) present the highest levels of total and free B after ACTH administration. We also found that animals from the front line of dispersion in Western Australia (WA) present the weakest adrenal response to a DEX-ACTH test. The animals categorized as long established in Queensland Australia (QL), and native in Mexico (MX), do not shown a marked difference in the HPA activity. Finally we found that in response to ACTH administration, females reach significantly higher levels of plasma B than males. For the first time the adrenocortical response in cane toads exposed to different experimental procedures, as well as from different populations was assessed systematically.

      PubDate: 2016-02-11T20:07:06Z
  • BbrzSP-32, the first serine protease isolated from Bothrops brazili venom:
           Purification and characterization
    • Abstract: Publication date: Available online 28 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Kayena D. Zaqueo, Anderson M. Kayano, Thaisa F.S. Domingos, Laura A. Moura, André L. Fuly, Saulo L. da Silva, Gerardo Acosta, Eliandre Oliveira, Fernando Albericio, Fernando B. Zanchi, Juliana P. Zuliani, Leonardo A. Calderon, Rodrigo G. Stábeli, Andreimar M. Soares
      Snake venom toxins are related not only in detention, death and the promotion of initial digestion of prey but also due to their different biochemical, structural and pharmacological effects they can result in new drugs. Among these toxins snake venom serine proteases (SVSPs) should be highlighted because they are responsible for inducing changes in physiological functions such as blood coagulation, fibrinolysis, and platelet aggregation. This article presents the first serine protease (SP) isolated from Bothrops brazili: BbrzSP-32. The new SP showed 36kDa of relative molecular mass and its absolute mass was confirmed by mass spectrometry as 32,520Da. It presents 79.48% identity when compared to other SVSPs and was able to degrade the α-chain of fibrinogen, in in vitro models, because of this it is considered a SVTLE-A. It showed dose-dependent activity in the process of degradation of fibrin networks demonstrating greater specificity for this activity when compared to its thrombolytic action. BbrzSP-32 demonstrated proteolytic activity on gelatin and chromogenic substrates for serine proteases and thrombin-like enzymes (S-2288 and S-2238 respectively), besides having coagulant activity on human plasma. After pre-incubation with PMSF and benzamidine the coagulant and proteolytic activities on the S-2288 and S-2238 substrates were reduced. BbrzSP-32 shows stability against pH and temperature variations, demonstrating optimum activity between 30 and 40°C and in the pH range 7.5 to 8.5. A new SP with potential biotechnological application was isolated.

      PubDate: 2016-01-28T16:54:22Z
  • Bohr effect and temperature sensitivity of hemoglobins from highland and
           lowland deer mice
    • Abstract: Publication date: Available online 22 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Birgitte Jensen, Jay F. Storz, Angela Fago
      An important means of physiological adaptation to environmental hypoxia is an increased oxygen (O2) affinity of the hemoglobin (Hb) that can help secure high O2 saturation of arterial blood. However, the trade-off associated with a high Hb–O2 affinity is that it can compromise O2 unloading in the systemic capillaries. High-altitude deer mice (Peromyscus maniculatus) have evolved an increased Hb–O2 affinity relative to lowland conspecifics, but it is not known whether they have also evolved compensatory mechanisms to facilitate O2 unloading to respiring tissues. Here we investigate the effects of pH (Bohr effect) and temperature on the O2-affinity of high- and low-altitude deer mouse Hb variants, as these properties can potentially facilitate O2 unloading to metabolizing tissues. Our experiments revealed that Bohr factors for the high- and low-altitude Hb variants are very similar in spite of the differences in O2-affinity. The Bohr factors of deer mouse Hbs are also comparable to those of other mammalian Hbs. In contrast, the high- and low-altitude variants of deer mouse Hb exhibited similarly low temperature sensitivities that were independent of red blood cell anionic cofactors, suggesting an appreciable endothermic allosteric transition upon oxygenation. In conclusion, high-altitude deer mice have evolved an adaptive increase in Hb–O2 affinity, but this is not associated with compensatory changes in sensitivity to changes in pH or temperature. Instead, it appears that the elevated Hb–O2 affinity in high-altitude deer mice is compensated by an associated increase in the tissue diffusion capacity of O2 (via increased muscle capillarization), which promotes O2 unloading.

      PubDate: 2016-01-28T16:54:22Z
  • Tissue-specific expression of ghrelinergic and NUCB2/nesfatin-1 systems in
           goldfish (Carassius auratus) is modulated by macronutrient composition of
    • Abstract: Publication date: Available online 22 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ayelén M. Blanco, Juan I. Bertucci, María J. Delgado, Ana I. Valenciano, Suraj Unniappan
      The macronutrient composition of diets is a very important factor in the regulation of body weight and metabolism. Several lines of research in mammals have shown that macronutrients differentially regulate metabolic hormones, including ghrelin and nesfatin-1 that have opposing effects on energy balance. This study aimed to determine whether macronutrients modulate the expression of ghrelin and the nucleobindin-2 (NUCB2) encoded nesfatin-1 in goldfish (Carassius auratus). Fish were fed once daily on control, high-carbohydrate, high-protein, high-fat and very high-fat diets for 7 (short-term) or 28 (long-term) days. The expression of preproghrelin, ghrelin O-acyl transferase (goat), growth hormone secretagogue receptor 1 (ghs-r1) and nucb2/nesfatin-1 mRNAs was quantified in the hypothalamus, pituitary, gut and liver. Short-term feeding with fat-enriched diets significantly increased nucb2 mRNA levels in hypothalamus and liver, preproghrelin, goat and ghs-r1 expression in pituitary, and ghs-r1 expression in gut. Fish fed on a high-protein diet exhibited a significant reduction in preproghrelin and ghs-r1 mRNAs in the liver. After long-term feeding, fish fed on high-carbohydrate and very high-fat diets had significantly increased preproghrelin, goat and ghs-r1 expression in pituitary. Feeding on a high-carbohydrate diet also upregulated goat and ghs-r1 transcripts in gut, while feeding on a high-fat diet elicited the same effect only for ghs-r1 in liver. Nucb2 expression increased in pituitary, while it decreased in gut after long-term feeding of a high-protein diet. Collectively, these results show for the first time in fish that macronutrients differentially regulate the expression of the ghrelinergic and NUCB2/nesfatin-1 systems in central and peripheral tissues of goldfish.

      PubDate: 2016-01-28T16:54:22Z
  • The effect of maternal immunization on female oxidative status, yolk
           antioxidants and offspring survival in a songbird
    • Abstract: Publication date: Available online 23 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): G. Casasole, D. Costantini, M. Cichoń, J. Rutkowska
      Immune defense involves inflammatory reactions in which immune cells produce reactive oxygen species (ROS) to fight pathogens. ROS may however cause damage to the host if they are not balanced by antioxidant defenses. Therefore, one should expect individuals undergoing an immune reaction to use antioxidants to prevent oxidative stress. Antioxidants are vital compounds that provide important protection against oxidative damage of embryos and newly hatched chicks. Thus, during egg laying a female that contracted an infection may face a trade-off between the allocation of antioxidants into self-maintenance and into her offspring via the eggs. In our study we investigated whether immunized females face this trade-off and consequently modify the antioxidant allocation into the eggs and whether this allocation affects offspring performance. We injected female zebra finches (Taeniopygia guttata) with lipopolysaccharide prior to egg laying while some females were left unimmunized. We removed the second egg of each clutch, while we allowed the other eggs to hatch. We assessed oxidative stress in females 24h after immunization, yolk antioxidant capacity of the second egg of the clutch and survival success of the offspring until adulthood. Compared to controls, immunized females had higher oxidative damage, but similar plasma non-enzymatic antioxidant levels. The treatment did not affect yolk antioxidants, clutch size, laying date and offspring survival. However, we found a positive correlation between yolk antioxidant capacity and offspring survival, irrespective of the treatment. Our study suggests that our immune challenge may not have changed female strategy of antioxidant allocation between self-maintenance and offspring survival.

      PubDate: 2016-01-28T16:54:22Z
  • Water deprivation up-regulates urine osmolality and renal aquaporin 2 in
           Mongolian gerbils (Meriones unguiculatus)
    • Abstract: Publication date: Available online 19 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Meng-Meng Xu, De-Hua Wang
      To better understand how desert rodents adapt to water scarcity, we examined urine osmolality, renal distribution and expression of aquaporins (AQPs) in Mongolian gerbils (Meriones unguiculatus) during 7days of water deprivation (WD). Urine osmolality of the gerbils during WD averaged 7503mOsmkg−1. Renal distributions of AQP1, AQP2, and AQP3 were similar to that described in other rodents. After the 7day WD, renal AQP2 was up-regulated, while resting metabolic rate and total evaporative water loss decreased by 43% and 36%, respectively. Our data demonstrated that Mongolian gerbils showed high urine concentration, renal AQPs expression and body water conservation to cope with limited water availability, which may be critical for their survival during dry seasons in cold deserts.

      PubDate: 2016-01-22T16:42:40Z
  • Leptin expression in mandarin fish Siniperca chuatsi (Basilewsky):
           Regulation by postprandial and short-term fasting treatment
    • Abstract: Publication date: Available online 19 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Xiaochen Yuan, Aixuan Li, Xu-Fang Liang, Wei Huang, Yi Song, Shan He, Wenjing Cai, Ya-xiong Tao
      Most fish species possess duplicate leptin genes (LEP). Mandarin fish (Siniperca chuatsi) leptin A gene (sLEP-A) have been cloned in the previous study. In the present study, we cloned and characterized leptin B gene (sLEP-B) in mandarin fish, including a 471bp open reading frame (ORF) encoding a 158-amino acid protein. The three-dimensional (3D) structural model of sLEP-B protein showed a highly conserved of tertiary structure similar to that of other vertebrates. Genomic sequencing results indicated that sLEP-B possessed only one intron. This is the first report of the loss of an intron in LEP-B in Perciformes. The different distribution patterns of sLEPs suggest different physiological roles of these two genes. The presence of HNF3β, a liver-enriched transcription factor, only in sLEP-A indicated abundant expression and metabolic function of sLEP-A in the liver. In an in vivo experiment, the expressions of brain sLEP-A and sLEP-B were observed to increase after a meal. During the short-term fasting, the expressions of sLEPs in mandarin fish brain were decreased significantly. A persistent and significant increase in hepatic sLEP-A expression supported a relationship between leptin and food intake in mandarin fish. These results suggest that sLEP-A plays an important role in the regulation of energy homeostasis in this carnivorous fish, and sLEP-B is probably a specialized gene responsible for the central nervous system (CNS) control of energy regulation.

      PubDate: 2016-01-22T16:42:40Z
  • FXYD11 mediated modulation of Na+/K+-ATPase activity in gills of the
           brackish medaka (Oryzias dancena) when transferred to hypoosmotic or
           hyperosmotic environments
    • Abstract: Publication date: Available online 19 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chia-Hao Chang, Wen-Kai Yang, Chia-Hao Lin, Chao-Kai Kang, Cheng-Hao Tang, Tsung-Han Lee
      FXYD proteins regulate Na+/K+-ATPase (NKA), which is a primary active pump that provides the driving force that triggers osmoregulatory systems in teleosts. To explore the regulatory mechanisms between FXYD and NKA in euryhaline teleosts, the expression of NKA (mRNA, protein, and activity) and FXYD11 and their interaction were examined in the gills of brackish medaka (Oryzias dancena) when transferred from brackish water (BW; 15‰) to fresh water (FW) or seawater (SW; 35‰). The mRNA expression of Odfxyd11 and Odnka-α was elevated 48h post-hypoosmotic transfer. Moreover, FXYD11 protein and NKA activity were upregulated 12h after transfer to FW. When transferred to SW, the protein abundance of FXYD11 and the NKA α-subunit did not show apparent changes, while Odfxyd11 and Odnka-α mRNA expression and NKA activity increased significantly 12h and 1h post-transfer, respectively. To clarify the FXYD11 mechanisms involved in modulating NKA activity via their interaction, co-immunoprecipitation was further applied to O. dancena gills. The results revealed that the levels of protein–protein interaction between branchial NKA and FXYD11 increased acutely 12h after the transfer from BW to FW. However, immediate upregulation of NKA activity 1h following post-exposure to SW, without the elevation of protein–protein interaction levels, was found. Hence, branchial NKA activity of O. dancena was suggested to be rapidly regulated by FXYD11 interaction with NKA when acclimated to hypoosmotic environments. To the best of our knowledge, this is the first study that focuses on the efficacy of interactions between FXYD11 and NKA in the gills of euryhaline teleosts.

      PubDate: 2016-01-22T16:42:40Z
  • Low cost of gastric acid secretion during digestion in ball pythons
    • Abstract: Publication date: Available online 21 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Simon Nørgaard, Kim Andreassen, Christian Lind Malte, Sanne Enok, Tobias Wang
      Due to their large metabolic responses to digestion (specific dynamic action, SDA), snakes represent an interesting animal group to identify the underlying mechanisms for the postprandial rise in metabolism. The SDA response results from the energetic costs of many different processes ranging from prey handling, secretions by the digestive system, synthesis of enzymes, plasticity of most visceral organs, as well as protein synthesis and nitrogen excretion. The contribution of the individual mechanisms, however, remains elusive. Gastric acid secretion has been proposed to account for more than half of the SDA response, while other studies report much lower contributions of the gastric processes. To investigate the energetic cost of gastric acid secretion, ball pythons (Python regius) were fed meals with added amounts of bone meal (up to 25g bone meal kg−1 snake) to achieve a more four-fold rise in the buffer capacity of the meals. Direct measurements within the stomach lumen showed similar reduction in gastric pH when buffer capacity was increased, but we found no effects on the rise in oxygen consumption over the first three days of digestion. There was, however, a slower return of oxygen consumption to resting baseline. We conclude that gastric acid secretion only contributes modestly to the SDA response and propose that post-absorptive processes, such as increased protein synthesis, are likely to underlie the SDA response.

      PubDate: 2016-01-22T16:42:40Z
  • The effect of aerobic exercise and starvation on growth performance and
           postprandial metabolic response in juvenile southern catfish (Silurus
    • Abstract: Publication date: Available online 13 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Xiu-Ming Li, Li Liu, Jian-Ming Yuan, Yuan-Yuan Xiao, Shi-Jian Fu, Yao-Guang Zhang
      To investigate the effects of aerobic exercise and starvation on growth performance, postprandial metabolic response and their interaction in a sedentary fish species, either satiation-fed or starved juvenile southern catfish (Silurus meridionalis) were exercised at 25°C under three water velocities, i.e., nearly still water (control), 1 body length (bl) s−1 and 2 bl s−1, for eight weeks. Then, the feed intake (FI), food conversion efficiency (FCE), specific growth rate (SGR), morphological parameters, resting M ̇ O2 ( M ̇ O2rest) and postprandial M ̇ O2 responses of the experimental fish were measured. Exercise at a low velocity (1 bl s−1) showed no effect on any growth performance parameter, whereas exercise at a high velocity (2 bl s−1) exhibited higher FI but similar SGR due to the extra energy expenditure from swimming and consequent decreased FCE. Starvation led to a significant body mass loss, whereas the effect intensified in both exercise groups. Exercise resulted in improved cardio-respiratory capacity, as indicated by increased gill and heart indexes, whereas it exhibited no effect on resting and postprandial metabolism in S. meridionalis. The starved fish displayed significantly larger heart, gill and digestive tract indexes compared with the feeding fish, suggesting selective maintenance of cardio-respiratory and digestive function in this fish species during starvation. However, starved fish still exhibited impaired digestive performance, as evidenced by the prolonged duration and low postprandial metabolic increase, and this effect was further exacerbated in both the 1 and 2 bl s−1 exercise groups. These data suggest the following: (1) aerobic exercise produced no improvement in growth performance but may have led to the impairment of growth under insufficient food conditions; (2) the mass of different organs and tissues responded differently to aerobic exercise and starvation due to the different physiological roles they play; and (3) aerobic exercise had no effect on the postprandial metabolic response under a “normal feeding” situation, whereas it may have resulted in the impairment of the digestive capacity when food availability was low due to the competition of energy and oxygen under unfavorable conditions in juvenile S. meridionalis.

      PubDate: 2016-01-18T17:01:02Z
  • Maintenance of a fully functional digestive system during hibernation in
           the European hamster, a food-caching hibernator
    • Abstract: Publication date: Available online 13 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mathieu Weitten, Hugues Oudart, Caroline Habold
      Some small mammals limit energy expenditure during winter conditions through torpor bouts, which are characterized by a decrease in body temperature and metabolic rate. Individuals arise periodically from torpor to restore critical functions requiring euthermia. Although most of the species involved do not feed during hibernation and rely on body reserves to fulfil energy requirements (fat-storing species), others hoard food in a burrow (food-caching species) and can feed during interbout euthermy. Whereas fat-storing species undergo a marked atrophy of the digestive tract, food-caching species have to maintain a functional digestive system during hibernation. Our study aimed to evaluate the absorption capacities of a food-caching species, the European hamster, throughout the annual cycle. In vivo intestinal perfusions were conducted in different groups of hamsters (n=5) during the different life periods, namely before hibernation, in torpor, during interbout euthermy, and during summer rest. The triglyceride, non-esterified free fatty acid, starch, glucose and protein composition of the perfusate was evaluated before and after the 1h perfusion of a closed intestinal loop. Triglyceride, starch and protein hydrolysis rates were similar in hibernating (torpid and euthermic) and non-hibernating hamsters. Intestinal absorption of free fatty acid was also similar in all groups. However, glucose uptake rate was higher during hibernation than during the summer. In contrast with fat-storing species, the intestinal absorption capacities of food-caching species are fully maintained during hibernation to optimize nutrient assimilation during short interbout euthermy. In particular, glucose uptake rate is increased during hibernation to restore glycaemia and ensure glucose-dependent pathways.

      PubDate: 2016-01-18T17:01:02Z
  • The effect of temperature on postprandial metabolism of yellowfin tuna
           (Thunnus albacares)
    • Abstract: Publication date: Available online 12 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Dane H. Klinger, Jonathan J. Dale, Adrian C. Gleiss, Tyler Brandt, Ethan E. Estess, Luke Gardner, Benjamin Machado, Alex Norton, Luis Rodriguez, James Stiltner, Charles Farwell, Barbara A. Block
      Specific dynamic action (SDA), the increase in metabolic expenditure associated with consumption of a meal, represents a substantial portion of fish energy budgets and is highly influenced by ambient temperature. The effect of temperature on SDA has not been studied in yellowfin tuna (Thunnus albacares, Bonnaterre 1788), an active pelagic predator that occupies temperate and subtropical waters. The energetic cost and duration of SDA were calculated by comparing routine and post-prandial oxygen consumption rates. Mean routine metabolic rates in yellowfin tuna increased with temperature, from 136mgO2 kg−1 h−1 at 20°C to 211mgO2 kg−1 h−1 at 24°C. The mean duration of SDA decreased from 40.2h at 20°C to 33.1h at 24°C, while mean SDA coefficient, the percentage of energy in a meal that is consumed during digestion, increased from 5.9% at 20°C to 12.7% at 24°C. Digestion in yellowfin tuna is faster at a higher temperature but requires additional oxidative energy. Enhanced characterization of the role of temperature in SDA of yellowfin tuna deepens our understanding of tuna physiology and can help improve management of aquaculture and fisheries.

      PubDate: 2016-01-13T15:55:41Z
  • Measuring intestinal fluid transport in vitro: Gravimetric method versus
           non-absorbable marker
    • Abstract: Publication date: Available online 12 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jonathan M. Whittamore, Janet Genz, Martin Grosell, Rod W. Wilson
      The gut sac is a long-standing, widely used in vitro preparation for studying solute and water transport, and calculation of these fluxes requires an accurate assessment of volume. This is commonly determined gravimetrically by measuring the change in mass over time. While convenient this likely under-estimates actual net water flux (J v ) due to tissue edema. We evaluated whether the popular in vivo volume marker [14C]-PEG 4000, offers a more representative measure of J v in vitro. We directly compared these two methods in five teleost species (toadfish, flounder, rainbow trout, killifish and tilapia). Net fluid absorption by the toadfish intestine based on PEG was significantly higher, by almost 4-fold, compared to gravimetric measurements, compatible with the latter under-estimating J v . Despite this, PEG proved inconsistent for all of the other species frequently resulting in calculation of net secretion, in contrast to absorption seen gravimetrically. Such poor parallelism could not be explained by the absorption of [14C]-PEG (typically <1%). We identified a number of factors impacting the effectiveness of PEG. One was adsorption to the surface of sample tubes. While it was possible to circumvent this using unlabelled PEG 4000, this had a deleterious effect on PEG-based J v . We also found sequestration of PEG within the intestinal mucus. In conclusion, the short-comings associated with the accurate representation of J v by gut sac preparations are not overcome by [14C]-PEG. The gravimetric method therefore remains the most reliable measure of J v and we urge caution in the use of PEG as a volume marker.

      PubDate: 2016-01-13T15:55:41Z
  • Molecular and functional characterization of the vitellogenin receptor in
           oriental river prawn, Macrobrachium nipponense
    • Abstract: Publication date: Available online 7 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Hongkun Bai, Hui Qiao, Fajun Li, Hongtuo Fu, Sufei Jiang, Wenyi Zhang, Yuedi Yan, Yiwei Xiong, Shengming Sun, Shubo Jin, Yongsheng Gong, Yan Wu
      A complementary DNA (cDNA) that encodes the vitellogenin receptor (VgR) in the oriental river prawn, Macrobrachium nipponense, was cloned using expressed sequence tag analysis and a rapid amplification of cDNA ends approach. The coding region consists of 5920 base pairs (bp) that encode a 1902 amino acid protein, with a predicted molecular mass of 209kDa. The coding region is flanked by a 45bp 5ʹ-untranslated region (UTR) and a 166bp 3ʹ-UTR. The deduced amino acid sequence of the M. nipponense VgR cDNA had typically conserved domains, such as an extracellular, lipoprotein-binding domain, epidermal growth factor-like and O-glycosylation domains, a transmembrane domain and a short C-terminal, cytosolic tail. Quantitative real-time PCR (qPCR) indicated that Mn-VgR is highly expressed in the female ovary. Expression analysis by qPCR demonstrated the larval and ovarian developmental stage-specific expression pattern. As the ovaries developed, the expression level of Mn-VgR gradually increased during the reproductive cycle (stage I), to reach a peak in stage III. Levels then dropped as a new development cycle was entered after reproduction molting. Eyestalk ablation led to a significant increase in the expression of Mn-VgR during the ovarian development stages (P <0.05), when compared with the eyestalk-intact group. The investigation revealed that eyestalk ablation initially affected Mn-VgR expression and then influenced vitellogenesis. In adult females, VgR RNA interference (RNAi) dramatically delayed the maturation of the ovary, in accordance with the gonad somatic index. In addition, Mn-VgR RNAi led to vitellin depletion in the oocytes and the accumulation of vitellin in the hepatopancreas.

      PubDate: 2016-01-09T15:32:58Z
  • Bone sialoprotein keratan sulfate proteoglycan (BSP-KSPG) and FGF-23 are
           important physiological components of medullary bone
    • Abstract: Publication date: Available online 7 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jill A. Hadley, Maria Horvat-Gordon, Woo-Kyun Kim, Craig A. Praul, Dennis Burns, Roland M. Leach
      Medullary bone is a specialized bone found in the marrow cavity of laying birds. It provides a significant contribution to the calcium supply for egg shell formation. Medullary bone is distinguished from cortical bone by the presence of large amounts of a keratan sulfate proteoglycan (KSPG). The aims of the present experiment are to confirm the identity of the core protein of KSPG, identify a marker of medullary bone metabolism, and determine whether changes in keratan sulfate (KS) concentration in blood are associated with the egg-laying cycle. Using two different isolation techniques- one specific for bone and another for blood- we have identified bone sialoprotein (BSP) to be the core protein of this KSPG. We also determined that the amount of keratan sulfate (KS) in laying hen blood fluctuates in synchrony with the egg-laying cycle, and thus can serve as a specific marker for medullary bone metabolism. During the course of this investigation, we also found FGF-23 (phosphatonin) to be expressed in medullary bone, in synchrony with the egg-laying cycle. Western blotting was used to demonstrate the presence of this peptide in both laying hen blood and medullary bone extracts. The importance of FGF-23 (phosphatonin) and parathyroid hormone in normalizing the dramatic changes in plasma calcium and phosphorus during the 24h egg-laying cycle is discussed.

      PubDate: 2016-01-09T15:32:58Z
  • The potential impacts of migratory difficulty, including warmer waters and
           altered flow conditions, on the reproductive success of salmonid fishes
    • Abstract: Publication date: March 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 193
      Author(s): Miriam Fenkes, Holly A. Shiels, John L. Fitzpatrick, Robert L. Nudds
      Climate change and urbanisation of watercourses affect water temperatures and current flow velocities in river systems on a global scale. This represents a particularly critical issue for migratory fish species with complex life histories that use rivers to reproduce. Salmonids are migratory keystone species that provide substantial economical value to ecosystems and human societies. Consequently, a comprehensive understanding of the effects of environmental stressors on their reproductive success is critical in order to ensure their continued abundance during future climatic change. Salmonids are capital breeders, relying entirely on endogenous energy stores to fuel return migration to their natal spawning sites and reproduction upon arrival. Metabolic rates and cost of transport en-route increase with temperature and at extreme temperatures, swimming is increasingly fuelled anaerobically, resulting in an oxygen debt and reduced capacity to recover from exhaustive exercise. Thermally challenged salmonids also produce less viable gametes, which themselves are affected by water temperature after release. Passage through hydrological barriers and temperature changes both affect energy expenditure. As a result, important energetic tradeoffs emerge between extra energy used during migration and that available for other facets of the reproductive cycle, such as reproductive competition and gamete production. However, studies identifying these tradeoffs are extremely sparse. This review focuses on the specific locomotor responses of salmonids to thermal and hydrological challenges, identifying gaps in our knowledge and highlighting the potential implications for key aspects of their reproduction.

      PubDate: 2015-12-20T10:17:46Z
  • Effects of seawater alkalinity on calcium and acid–base regulation
           in juvenile European lobster (Homarus gammarus) during a moult cycle
    • Abstract: Publication date: Available online 10 December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Karen L. Middlemiss, Mauricio A. Urbina, Rod W. Wilson
      Fluxes of NH4 + (acid) and HCO3 − (base), and whole body calcium content were measured in European lobster (Homarus gammarus) during intermoult (megalopae stage), and during the first 24h for postmoult juveniles under control (~2000μeq/L) and low seawater alkalinity (~830μeq/L). Immediately after moulting, animals lost 45% of the total body calcium via the shed exoskeleton (exuvia), and only 11% was retained in the uncalcified body. At 24h postmoult, exoskeleton calcium increased to ~46% of the intermoult stage. Ammonia excretion was not affected by seawater alkalinity. After moulting bicarbonate excretion was immediately reversed from excretion to uptake (~4–6 fold higher rates than intermoult) over the whole 24h postmoult period, peaking at 3–6h. These data suggest that exoskeleton calcification is not completed by 24h postmoult. Low seawater alkalinity reduced postmoult bicarbonate uptake by 29% on average. Net acid–base flux (equivalent to net base uptake) followed the same pattern as HCO3 − fluxes, and was 22% lower in low alkalinity seawater over the whole 24h postmoult period. The common occurrence of low alkalinity in intensive aquaculture systems may slow postmoult calcification in juvenile H. gammarus, increasing the risk of mortalities through cannibalism.

      PubDate: 2015-12-12T10:03:31Z
  • Effects of short-term hyper- and hypo-osmotic exposure on the
           osmoregulatory strategy of unfed North Pacific spiny dogfish (Squalus
    • Abstract: Publication date: Available online 11 December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Courtney A. Deck, Abigail B. Bockus, Brad A. Seibel, Patrick J. Walsh
      The North Pacific spiny dogfish (Squalus suckleyi) is a partially euryhaline species of elasmobranch that often enter estuaries where they experience relatively large fluctuations in environmental salinity that can affect plasma osmolality. Previous studies have investigated the effects of altered salinity on elasmobranchs over the long term, but fewer studies have conducted time courses to investigate how rapidly they can adapt to such changes. In this study, we exposed unfed (no exogenous source of nitrogen or TMAO) spiny dogfish to hyper- and hypo-osmotic conditions and measured plasma and tissue osmolytes, nitrogen excretion, and changes in enzyme activity and mRNA levels in the rectal gland over 24h. It was shown that plasma osmolality changes to approximately match the ambient seawater within 18-24h. In the hypersaline environment, significant increases in urea, sodium, and chloride were observed, whereas in the hyposaline environment, only significant decreases in TMAO and sodium were observed. Both urea and ammonia excretion increased at low salinities suggesting a reduction in urea retention and possibly urea production. qPCR and enzyme activity data for Na+/K+-ATPase did not support the idea of rectal gland activation following exposure to increased salinities. Therefore, we suggest that the rectal gland may not be a quantitatively important aspect of the dogfish osmoregulatory strategy during changes in environmental salinity, or it may be active only in the very early stages (i.e., less than 6h) of responses to altered salinity.

      PubDate: 2015-12-12T10:03:31Z
  • Thermal Stress and the Heat Shock Response in Embryonic and Young of the
           Year Juvenile Lake Whitefish
    • Abstract: Publication date: Available online 3 December 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel I. Stefanovic, Lori A. Manzon, Chance S. McDougall, Douglas R. Boreham, Christopher M. Somers, Joanna Y. Wilson, Richard G. Manzon
      We investigated the effects of thermal stress on embryonic (fin flutter, vitelline circulation stage) and young of the year (YOY) juvenile lake whitefish by characterizing the kinetics of the heat shock response (HSR). Lake whitefish were subjected to one of three different heat shock (HS) temperatures (3, 6, or 9°C above control) for six different lengths of time (0.25, 0.50, 1, 2, 3, or 4 h) followed by a 2 h recovery period at the control temperature of 2°C or 14°C for embryos and YOY juveniles, respectively. The duration of the HSR was examined by allowing the fish to recover for 1, 2, 4, 8, 12, 16, 24, 36, or 48 h following a 2 h HS. In embryos, at the fin flutter stage, only hsp70 mRNA levels were upregulated in response to the various HS treatments. By comparison, all three typically inducible hsps, hsp90α, hsp70 and hsp47, were upregulated in the YOY juveniles. In both instances the HSR was long lasting, but much more so in embryos where hsp70 mRNA levels continued to increase for 48 h after a 2 h HS and remained significantly higher than untreated controls. Collectively our data indicate that both embryo and YOY juvenile lake whitefish have a robust HSR which permits them to survive a 4 h, 9°C HS. Moreover, both life history stages are capable of triggering a HSR following a moderate 3°C HS which is likely an important protective mechanism against environmental stressors during embryogenesis and early life history stages of lake whitefish.

      PubDate: 2015-12-03T09:32:50Z
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