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  Subjects -> BIOLOGY (Total: 2912 journals)
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BIOCHEMISTRY (217 journals)                  1 2 3     

AAPS PharmSciTech     Hybrid Journal   (Followers: 7)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Central Science     Hybrid Journal  
ACS Chemical Biology     Full-text available via subscription   (Followers: 159)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 16)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 11)
Acta Crystallographica Section F: Structural Biology Communications     Hybrid Journal   (Followers: 6)
Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 9)
Advances in Biological Chemistry     Open Access   (Followers: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 10)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 7)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 12)
African Journal of Biochemistry Research     Open Access   (Followers: 1)
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 7)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 72)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Polymer Science     Open Access   (Followers: 22)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 83)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 39)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 21)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 9)
Applied Organometallic Chemistry     Hybrid Journal   (Followers: 5)
Archives of Biochemistry and Biophysics     Hybrid Journal   (Followers: 10)
Archives of Insect Biochemistry and Physiology     Hybrid Journal   (Followers: 1)
Archives Of Physiology And Biochemistry     Hybrid Journal   (Followers: 1)
Asian Journal of Biochemistry     Open Access   (Followers: 1)
Asian Journal of Biomedical and Pharmaceutical Sciences     Open Access   (Followers: 2)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
BBA Clinical     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Biocatalysis     Open Access  
Biochemical and Biophysical Research Communications     Hybrid Journal   (Followers: 14)
Biochemical and Molecular Medicine     Full-text available via subscription   (Followers: 5)
Biochemical Compounds     Open Access  
Biochemical Engineering Journal     Hybrid Journal   (Followers: 10)
Biochemical Genetics     Hybrid Journal   (Followers: 3)
Biochemical Journal     Full-text available via subscription   (Followers: 20)
Biochemical Pharmacology     Hybrid Journal   (Followers: 6)
Biochemical Society Transactions     Full-text available via subscription   (Followers: 3)
Biochemical Systematics and Ecology     Hybrid Journal   (Followers: 4)
Biochemistry     Full-text available via subscription   (Followers: 163)
Biochemistry & Pharmacology : Open Access     Open Access   (Followers: 1)
Biochemistry & Physiology : Open Access     Open Access  
Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 10)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 5)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 16)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 5)
Biochimie     Hybrid Journal   (Followers: 5)
Bioconjugate Chemistry     Full-text available via subscription   (Followers: 16)
BioDrugs     Full-text available via subscription   (Followers: 9)
Bioelectrochemistry     Hybrid Journal   (Followers: 2)
Biofuels     Hybrid Journal   (Followers: 11)
Biogeochemistry     Hybrid Journal   (Followers: 10)
BioInorganic Reaction Mechanisms     Hybrid Journal   (Followers: 1)
Biokemistri     Open Access  
Biological Chemistry     Partially Free   (Followers: 13)
Biomaterials Research     Open Access   (Followers: 1)
Biomedicines     Open Access   (Followers: 1)
BioMolecular Concepts     Hybrid Journal   (Followers: 2)
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 7)
Biosimilars     Open Access   (Followers: 1)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 24)
BMC Biochemistry     Open Access   (Followers: 12)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 5)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 6)
ChemBioChem     Hybrid Journal   (Followers: 3)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 22)
Chemical Engineering Journal     Hybrid Journal   (Followers: 24)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Open Access   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 20)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
ChemTexts     Hybrid Journal  
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 8)
Clinical Chemistry and Laboratory Medicine     Hybrid Journal   (Followers: 21)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 1)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 2)

        1 2 3     

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  [2801 journals]
  • 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
       
  • How widespread is preparation for oxidative stress in the animal
           kingdom'
    • Abstract: Publication date: Available online 4 February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel C. Moreira, Larissa P.R. Venancio, Marcus A.C.T. Sabino, Marcelo Hermes-Lima



      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
           ultrasound
    • 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
           diets
    • 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
           meridionalis)
    • 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
       
  • Complex flow in the nasal region of guitarfishes
    • Abstract: Publication date: Available online 15 January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Mawuli P.K. Agbesi, Sara Naylor, Elizabeth Perkins, Heather S. Borsuk, Dan Sykes, James S. Maclaine, Zhijin Wang, Jonathan P.L. Cox
      Scent detection in an aquatic environment is dependent on the movement of water. We set out to determine the mechanisms for moving water through the olfactory organ of guitarfishes (Rhinobatidae, Chondrichthyes) with open nasal cavities. We found at least two. In the first mechanism, which we identified by observing dye movement in the nasal region of a life-sized physical model of the head of Rhinobatos lentiginosus mounted in a flume, olfactory flow is generated by the guitarfish's motion relative to water, e.g. when it swims. We suggest that the pressure difference responsible for motion-driven olfactory flow is caused by the guitarfish's nasal flaps, which create a region of high pressure at the incurrent nostril, and a region of low pressure in and behind the nasal cavity. Vortical structures in the nasal region associated with motion-driven flow may encourage passage of water through the nasal cavity and its sensory channels, and may also reduce the cost of swimming. The arrangement of vortical structures is reminiscent of aircraft wing vortices. In the second mechanism, which we identified by observing dye movement in the nasal regions of living specimens of Glaucostegus typus, the guitarfish's respiratory pump draws flow through the olfactory organ in a rhythmic (0.5–2Hz), but continuous, fashion. Consequently, the respiratory pump will maintain olfactory flow whether the guitarfish is swimming or at rest. Based on our results, we propose a model for olfactory flow in guitarfishes with open nasal cavities, and suggest other neoselachians which this model might apply to.


      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
       
  • Editorial Board
    • Abstract: Publication date: February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 192




      PubDate: 2015-12-16T10:12:12Z
       
  • 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
       
  • Salinity effects on plasma ion levels, cortisol, and osmolality in Chinook
           salmon following lethal sampling
    • Abstract: Publication date: February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 192
      Author(s): Heather A. Stewart, David L.G. Noakes, Karen M. Cogliati, James T. Peterson, Martin H. Iversen, Carl B. Schreck
      Studies on hydromineral balance in fishes frequently employ measurements of electrolytes following euthanasia. We tested the effects of fresh- or salt-water euthanasia baths of tricaine mesylate (MS-222) on plasma magnesium (Mg2+) and sodium (Na+) ions, cortisol and osmolality in fish exposed to saltwater challenges, and the ion and steroid hormone fluctuations over time following euthanasia in juvenile spring Chinook salmon (Oncorhynchus tshawytscha). Salinity of the euthanasia bath affected plasma Mg2+ and Na+ concentrations as well as osmolality, with higher concentrations in fish euthanized in saltwater. Time spent in the bath positively affected plasma Mg2+ and osmolality, negatively affected cortisol, and had no effect on Na+ concentrations. The difference of temporal trends in plasma Mg2+ and Na+ suggests that Mg2+ may be more sensitive to physiological changes and responds more rapidly than Na+. When electrolytes and cortisol are measured as endpoints after euthanasia, care needs to be taken relative to time after death and the salinity of the euthanasia bath.


      PubDate: 2015-12-12T10:03:31Z
       
  • Closed system respirometry may underestimate tissue gas exchange and bias
           the respiratory exchange ratio (RER)
    • Abstract: Publication date: February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 192
      Author(s): Christian Lind Malte, Simon Nørgaard, Tobias Wang
      Closed respirometry is a commonly used method to measure gas exchange in animals due to its apparent simplicity. Typically, the rates of O2 uptake and CO2 excretion ( V ˙ O2 and V ˙ CO2, respectively) are assumed to be in steady state, such that the measured rates of gas exchange equal those at tissue level. In other words, the respiratory gas exchange ratio (RER) is assumed to equal the respiratory quotient (RQ). However, because the gas concentrations change progressively during closure, the animal inspires air with a progressively increasing CO2 concentration and decreasing O2 concentration. These changes will eventually affect gas exchange causing the O2 and CO2 stores within the animal to change. Because of the higher solubility/capacitance of CO2 in the tissues of the body, V ˙ CO2 will be more affected than V ˙ O2, and we hypothesize therefore that RER will become progressively underestimated as closure time is prolonged. This hypothesis was addressed by a combination of experimental studies involving closed respirometry on ball pythons (Python regius) as well as mathematical models of gas exchange. We show that increased closed duration of the respirometer reduces RER by up to 13%, and these findings may explain previous reports of RER values being below 0.7. Our model reveals that the maximally possible reduction in RER is determined by the storage capacity of the body for CO2 (product of size and specific capacitance) relative to the respirometer storage capacity. Furthermore, modeling also shows that pronounced ventilatory and circulatory response to hypercapnia can alleviate the reduction in RER.


      PubDate: 2015-12-12T10:03:31Z
       
  • Does oxygen limit thermal tolerance in arthropods? A critical review
           of current evidence
    • Abstract: Publication date: February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 192
      Author(s): Wilco C.E.P. Verberk, Johannes Overgaard, Rasmus Ern, Mark Bayley, Tobias Wang, Leigh Boardman, John S. Terblanche
      Over the last decade, numerous studies have investigated the role of oxygen in setting thermal tolerance in aquatic animals, and there has been particular focus on arthropods. Arthropods comprise one of the most species-rich taxonomic groups on Earth, and display great diversity in the modes of ventilation, circulation, blood oxygen transport, with representatives living both in water (mainly crustaceans) and on land (mainly insects). The oxygen and capacity limitation of thermal tolerance (OCLTT) hypothesis proposes that the temperature dependent performance curve of animals is shaped by the capacity for oxygen delivery in relation to oxygen demand. If correct, oxygen limitation could provide a mechanistic framework to understand and predict both current and future impacts of rapidly changing climate. In arthropods, most studies testing the OCLTT hypothesis have considered tolerance to thermal extremes. These studies likely operate from the philosophical viewpoint that if the model can predict these critical thermal limits, then it is more likely to also explain loss of performance at less extreme, non-lethal temperatures, for which much less data is available. Nevertheless, the extent to which lethal temperatures are influenced by limitations in oxygen supply remains unresolved. Here we critically evaluate the support and universal applicability for oxygen limitation being involved in lethal temperatures in crustaceans and insects. The relatively few studies investigating the OCLTT hypothesis at low temperature do not support a universal role for oxygen in setting the lower thermal limits in arthropods. With respect to upper thermal limits, the evidence supporting OCLTT is stronger for species relying on underwater gas exchange, while the support for OCLTT in air-breathers is weak. Overall, strongest support was found for increased anaerobic metabolism close to thermal maxima. In contrast, there was only mixed support for the prediction that aerobic scope decreases near critical temperatures, a key feature of the OCLTT hypothesis. In air-breathers, only severe hypoxia (<2kPa) affected heat tolerance. The discrepancies for heat tolerance between aquatic and terrestrial organisms can to some extent be reconciled by differences in the capacity to increase oxygen transport. As air-breathing arthropods are unlikely to become oxygen limited under normoxia (especially at rest), the oxygen limitation component in OCLTT does not seem to provide sufficient information to explain lethal temperatures. Nevertheless, many animals may simultaneously face hypoxia and thermal extremes and the combination of these potential stressors is particularly relevant for aquatic organisms where hypoxia (and hyperoxia) is more prevalent. In conclusion, whether taxa show oxygen limitation at thermal extremes may be contingent on their capacity to regulate oxygen uptake, which in turn is linked to their respiratory medium (air vs. water). Fruitful directions for future research include testing multiple predictions of OCLTT in the same species. Additionally, we call for greater research efforts towards studying the role of oxygen in thermal limitation of animal performance at less extreme, sub-lethal temperatures, necessitating studies over longer timescales and evaluating whether oxygen becomes limiting for animals to meet energetic demands associated with feeding, digestion and locomotion.


      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
           suckleyi)
    • 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
       
  • Editorial Board
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191




      PubDate: 2015-11-29T09:11:42Z
       
  • Seasonal dietary shifting in yellow-rumped warblers is unrelated to
           macronutrient targets
    • Abstract: Publication date: Available online 25 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Taylor J. Marshall, Morag F. Dick, Christopher G. Guglielmo
      Dietary shifting, for example from insects to fruits, is a common mechanism used in migratory songbirds to accumulate fat to fuel migratory flights. We examined a potential underlying cause of dietary shifting in yellow-rumped warblers (Setophaga coronata) by comparing energy and protein intake goals of birds during fall migration and winter. We offered captive warblers pairs of three diets differing in macronutrient composition in both the fall and winter. Using the principles of the geometric framework of nutrition we evaluated protein and energy intake to determine if consumption of the diet pairs was adjusted to meet an energy or protein intake target, and if the target differed seasonally. Regardless of season, the warblers preferred the diet with the lowest protein content and highest carbohydrate content. Total energy intake was maintained relatively constant during migration, at around 60kJ/day, regardless of diet combination, and at about 50kJ/day during winter. This suggests that warblers consume macronutrients available to them without protein limitations to reach their total energy intake target. When the diet combination offered allows, the warblers mixed their diet intake to consume roughly 0.5g/day of protein, regardless of season, which suggested a constant protein target. Our findings suggest that songbirds prefer to alter non-protein energy intake proportionally to meet changing energy demand, rather than an overall increase in macronutrient intake. Additionally, they have the ability to shift their diet based on availability, resulting in high flexibility in their macronutrient intakes to maintain energy intake.


      PubDate: 2015-11-29T09:11:42Z
       
  • Effects of mild wintering conditions on body mass and corticosterone
           levels in a temperate reptile, the aspic viper (Vipera aspis)
    • Abstract: Publication date: Available online 25 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): François Brischoux, Andréaz Dupoué, Olivier Lourdais, Frédéric Angelier
      Temperate ectotherms are expected to benefit from climate change (e.g., increased activity time), but the impacts of climate warming during the winter have mostly been overlooked. Milder winters are expected to decrease body condition upon emergence, and thus to affect crucial life-history traits, such as survival and reproduction. Mild winter temperature could also trigger a state of chronic physiological stress due to inadequate thermal conditions that preclude both dormancy and activity. We tested these hypotheses on a typical temperate ectothermic vertebrate, the aspic viper (Vipera aspis). We simulated different wintering conditions for three groups of aspic vipers (cold: ~6°C, mild: ~14°C and no wintering: ~24°C) during a one month long period. We found that mild wintering conditions induced a marked decrease in body condition, and provoked an alteration of some hormonal mechanisms involved in emergence. Such effects are likely to bear ultimate consequences on reproduction, and thus population persistence. We emphasize that future studies should incorporate the critical, albeit neglected, winter season when assessing the potential impacts of global changes on ectotherms.


      PubDate: 2015-11-29T09:11:42Z
       
  • Seasonal variation in baseline and maximum whole-body glucocorticoid
           concentrations in a small-bodied stream fish independent of habitat
           quality
    • Abstract: Publication date: February 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 192
      Author(s): Cassia B. Belanger, Marilyn N. Vera-Chang, Thomas W. Moon, Jonathan D. Midwood, Cory D. Suski, Steven J. Cooke
      Alterations to natural habitats are becoming more common due to changes in anthropogenic land use. As such, there is increasing interest in determining how wild animals adapt and respond to environmental stressors. The glucocorticoid (GC) stress response enables animals to react appropriately to environmental challenges but can be affected by many factors, two of which are habitat quality and time of year (i.e., season). This study tested whether baseline and maximum (stress-induced) whole-body cortisol concentrations varied in relation to habitat quality and season using wild central mudminnows (Umbra limi) collected from two connected streams differing in habitat quality in each of four seasons. Overall, baseline and maximum cortisol levels did not differ significantly between the two systems but there was evidence of a seasonal effect. Baseline cortisol levels in the fall and summer were significantly (P <0.01) lower than those in winter and spring and maximum cortisol levels in the summer were significantly lower (P <0.01) than those in the spring. Inconsistent with the prevailing paradigm, our results indicate that habitat quality does not always influence baseline GCs or the stress response. In contrast, baseline and maximum GCs in this species do vary seasonally. As such, seasonality should be considered in the interpretation of stress response data especially when using small-bodied stream fish as biological indicators.


      PubDate: 2015-11-21T03:35:32Z
       
  • Impact of different temperatures on survival and energy metabolism in the
           Asian citrus psyllid, Diaphorina citri Kuwayama
    • Abstract: Publication date: Available online 18 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ibrahim El-Shesheny, Faraj Hijaz, Ibrahim El-Hawary, Ibrahim Mesbah, Nabil Killiny
      Temperature influences the life history and metabolics parameters of insects. Asian citrus psyllid (ACP), Diaphorina citri is a tropical and subtropical pest. ACP invaded new regions around the world and threatened the citrus industry as a vector for Huanglongbing (HLB) disease. ACP is widely distributed and can survive high (up to 45°C) and low temperatures (as low as -6 °C). The precise mechanism of temperature tolerance in ACP is poorly understood. We investigated adult survival, cellular energy balance, gene expression, and nucleotides and sugar-nucleotides changes under the effect of different temperature regimes (0 °C to 45 °C with 5 °C intervals). The optimum temperatures for survival were 20 and 25 °C. Low temperatures of 0 °C and 5 °C caused 50% mortality after 2 and 4 days respectively, while one day at high temperature (40 °C and 45 °C) caused more than 95% mortality. The lowest quantity of ATP (3.69±1.6 ng/insect) and the maximum ATPase enzyme activities (57.43±7.6 μU/insect) were observed at 25 °C. Correlation between ATP quantities and ATPase activity was negative. Gene expression of hsp70, V-type proton ATPase catalytic subunit A and ATP synthase α subunit matched these results. Twenty-four nucleotides and sugar-nucleotides were quantified using HPLC in ACP adults maintained at low, high, and optimum temperatures. The nucleotide profiles were different among treatments. The ratios between AMP:ATP and ADP:ATP were significantly decreased and positively correlated to adults survival, whereas the adenylate energy charge was increased in response to low and high temperatures. Exploring energy metabolic regulation in relation with adult survival might help in understanding the physiological basis of how ACP tolerates newly invaded regions.


      PubDate: 2015-11-21T03:35:32Z
       
  • Effects of wintertime fasting and seasonal adaptation on AMPK and ACC in
           hypothalamus, adipose tissue and liver of the raccoon dog (Nyctereutes
           procyonoides)
    • Abstract: Publication date: Available online 18 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sanni Kinnunen, Satu Mänttäri, Karl-Heinz Herzig, Petteri Nieminen, Anne-Mari Mustonen, Seppo Saarela
      The raccoon dog (Nyctereutes procyonoides) is a canid with autumnal fattening and passive wintering strategy. We examined the effects of wintertime fasting and seasonality on AMP-activated protein kinase (AMPK), a regulator of metabolism, and its target, acetyl-CoA carboxylase (ACC) on the species. Twelve farmed raccoon dogs (eleven females/one male) were divided into two groups: half were fasted for ten weeks in December–March (winter fasted) and the others were fed ad libitum (winter fed). A third group (autumn fed, eight females) was fed ad libitum and sampled in December. Total AMPK, ACC and their phosphorylated forms (pAMPK, pACC) were measured from hypothalamus, liver, intra-abdominal (iWAT) and subcutaneous white adipose tissues (sWAT). The fasted animals lost 32% and the fed 20% of their body mass. Hypothalamic AMPK expression was lower and pACC levels higher in the winter groups compared to the autumn fed group. Liver pAMPK was lower in the winter fasted group, with consistently decreased ACC and pACC. AMPK and pAMPK were down-regulated in sWAT and iWAT of both winter groups, with a parallel decline in pACC in sWAT. The responses of AMPK and ACC to fasting were dissimilar to the effects observed previously in non-seasonal mammals and also hibernators. Differences between the winter fed and autumn fed groups indicate that the functions of AMPK and ACC could be regulated in a season-dependent manner. Furthermore, the distinctive effects of prolonged fasting and seasonal adaptation on AMPK–ACC pathway could contribute to the wintering strategy of the raccoon dog.


      PubDate: 2015-11-21T03:35:32Z
       
  • A comparative study of the response to repeated chasing stress in Atlantic
           salmon (Salmo salar L.) parr and post-smolts
    • Abstract: Publication date: Available online 7 November 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Angelico Madaro, Rolf Erik Olsen, Tore S. Kristiansen, Lars O.E. Ebbesson, Gert Flik, Marnix Gorissen
      When Atlantic salmon parr migrate from fresh water towards the sea, they undergo extensive morphological, neural, physiological and behavioural changes. Such changes have the potential to affect their responsiveness to various environmental factors that impose stress. In this study we compared the stress responses in parr and post-smolt salmon following exposure to repeated chasing stress (RCS) for three weeks. At the end of this period, all fish were challenged with a novel stressor and sampled before (T0) and after 1h (T1). Parr had a higher growth rate than post-smolts. Plasma cortisol declined in the RCS groups within the first week suggesting a rapid habituation/desensitisation of the endocrine stress axis. As a result of the desensitised HPI axis, RCS groups showed a reduced cortisol response when exposed to the novel stressor. In preoptic area (POA) crf mRNA levels were higher in all post-smolt groups compared to parr. 11βhsd2 decreased by RCS and by the novel stressor in post-smolt controls (T1), whereas no effect of either stress was seen in parr. The grs were low in all groups except for parr controls. In pituitary, parr controls had higher levels of crf1r mRNA than the other parr and post-smolt groups, whilst pomcb was higher in post-smolt control groups. Overall, 11βhsd2 transcript abundance in parr was lower than post-smolt groups; after the novel stressor pomcs, grs and mr were up-regulated in parr control (T1). In summary, we highlight differences in the central stress response between parr and post-smolt salmon following RCS.


      PubDate: 2015-11-09T15:41:53Z
       
  • Vitamin A and arachidonic acid altered the skeletal mineralization in
           Atlantic cod (Gadus morhua) larvae without any interactions on the
           transcriptional level
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Kai Kristoffer Lie, Karen Kvalheim, Josef Daniel Rasinger, Torstein Harboe, Andreas Nordgreen, Mari Moren
      The main object of this study was to evaluate the impact of different levels of vitamin A (VA) and arachidonic acid (ARA) in relation to eicosapentaenoic acid (EPA) on mineralization and gene expression in Atlantic cod larvae (Gadus morhua). First-feeding larvae were fed enriched rotifers from start-feeding until 29days post hatch (dph). Larvae in four tanks were fed one of the following diets: control (EPA/ARA ratio: 15.8, 0.9μg VA g−1), control+VA (EPA/ARA ratio: 15.8, 7.8μg VA g−1), High ARA (EPA/ARA ratio: 0.9, 1.5μg VA g−1) or High ARA+VA (EPA/ARA ratio: 0.9, 12.0μg VA g−1). Larvae fed High ARA+VA were shorter at 29dph compared to the other groups and had significantly less mineralized bones when comparing larvae of similar size, showing interaction effects between VA and ARA. Although transcriptomic analysis did not reveal any interaction effects, a higher number of genes were differentially expressed in the high ARA fed larvae compared to control+VA fed larvae. Furthermore, bglap1, bglap2 and col10a1 were all down-regulated in larvae fed High ARA-diets and to a greater extent than larvae fed VA supplemented diet, indicating an additive effect on mineralization. In conclusion, this study showed that the dietary increase in ARA and VA altered the skeletal metabolism during larval development, most likely through signaling pathways specific for each nutrient rather than an interaction. The present study also demonstrates that VA could affect the larval response to ARA, even within the accepted non-toxic/non-deficient range.


      PubDate: 2015-10-28T10:11:25Z
       
  • Effect of sulfide, osmotic, and thermal stresses on taurine transporter
           mRNA levels in the gills of the hydrothermal vent-specific mussel
           Bathymodiolus septemdierum
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Ikumi Nakamura-Kusakabe, Toshihiro Nagasaki, Azusa Kinjo, Mieko Sassa, Tomoko Koito, Kei Okamura, Shosei Yamagami, Toshiro Yamanaka, Shinji Tsuchida, Koji Inoue
      Hydrothermal vent environmental conditions are characterized by high sulfide concentrations, fluctuating osmolality, and irregular temperature elevations caused by vent effluents. These parameters represent potential stressors for organisms that inhabit the area around hydrothermal vents. Here, we aimed to obtain a better understanding of the adaptation mechanisms of marine species to hydrothermal vent environments. Specifically, we examined the effect of sulfide, osmolality, and thermal stress on the expression of taurine transporter (TAUT) mRNA in the gill of the deep-sea mussel Bathymodiolus septemdierum, which is a dominant species around hydrothermal vent sites. We analyzed TAUT mRNA levels by quantitative real-time polymerase chain reaction (PCR) in the gill of mussels exposed to sulfide (0.1 or 1mg/L Na2S·9H2O), hyper- (115% seawater) and hypo- (97.5%, 95.5%, and 85% seawater) osmotic conditions, and thermal stresses (12°C and 20°C) for 24 and 48h. The results showed that mussels exposed to relatively low levels of sulfide (0.1mg/L) and moderate heat stress (12°C) exhibited higher TAUT mRNA levels than the control. Although hyper- and hypo-osmotic stress did not significantly change TAUT mRNA levels, slight induction was observed in mussels exposed to low osmolality. Our results indicate that TAUT is involved in the coping mechanism of mussels to various hydrothermal vent stresses.


      PubDate: 2015-10-28T10:11:25Z
       
  • Abundance of specific mRNA transcripts impacts hatching success in
           European eel, Anguilla anguilla L
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Christoffer Rozenfeld, Ian A.E. Butts, Jonna Tomkiewicz, Jose-Luis Zambonino-Infante, David Mazurais
      Maternal mRNA governs early embryonic development in fish and variation in abundance of maternal transcripts may contribute to variation in embryonic survival and hatch success in European eel, Anguilla anguilla. Previous studies have shown that quantities of the maternal gene products β-tubulin, insulin-like growth factor 2 (igf2), nucleoplasmin (npm2), prohibitin 2 (phb2), phosphatidylinositol glycan biosynthesis class F protein 5 (pigf5), and carnitine O-palmitoyltransferase liver isoform-like 1 (cpt1) are associated with embryonic developmental competence in other teleosts. Here, the relations between relative mRNA abundance of these genes in eggs and/or embryos and egg quality, was studied and analyzed. We compared egg quality of the two groups: i) batches with hatching and ii) batches with no hatching. Results showed no significant differences in relative mRNA abundance between the hatch and no hatching groups for any of the selected genes at 0, 2.5, and 5HPF. However, at 30HPF the hatch group showed significantly higher abundance of cpt1a, cpt1b, β-tubulin, phb2, and pigf5 transcripts than the no hatch group. Therefore, these results indicate that up-regulation of the transcription of these genes in European eel after the mid-blastula transition, may be needed to sustain embryonic development and hatching success.


      PubDate: 2015-10-28T10:11:25Z
       
  • Role of calcium on the initiation of sperm motility in the European eel
    • Abstract: Publication date: Available online 11 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Luz Pérez, M. Carmen Vílchez, Víctor Gallego, Marina Morini, David S. Peñaranda, Juan F. Asturiano
      Sperm from European eel males treated with hCGrec was washed in a calcium free extender, and sperm motility was activated both in the presence (seawater, SW) and in the absence of calcium (NaCl+EDTA), and treated with calcium inhibitors or modulators. The sperm motility parameters were evaluated by a computer-assisted sperm analysis (CASA) system, and changes in the [Ca2+]i fluorescence (and in [Na+]i in some cases) were evaluated by flow cytometry. After sperm motility was activated in a medium containing Ca2+ (seawater, SW) the intracellular fluorescence emitted by Ca2+ increased 4-6-fold compared to the levels in quiescent sperm. However, whilst sperm activation in a Ca-free media (NaCl+EDTA) resulted in a percentage of motility similar to seawater, the [Ca2+]i levels did not increase at all. This result strongly suggests that increasing [Ca2+]i is not a pre-requisite for the induction of sperm motility in European eel sperm. Several sperm velocities (VCL, VSL, VAP) decreased when sperm was activated in the Ca-free activator, thus supporting the theory that Ca2+ has a modulatory effect on sperm motility. The results indicate that a calcium/sodium exchanger (NCX) which is inhibited by bepridil and a calcium calmodulin kinase (inhibited by W-7), are involved in the sperm motility of the European eel. Our results indicate that the increase in [Ca2+]i concentrations during sperm activation is due to an influx from the external medium, but, unlike in most other species, it does not appear to be necessary for the activation of motility in European eel sperm.


      PubDate: 2015-10-11T23:55:26Z
       
  • Exogenous administration of chronic corticosterone affects hepatic
           cholesterol metabolism in broiler chickens showing long or short tonic
           immobility
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Jie Liu, Yujing Duan, Yun Hu, Lili Sun, Song Wang, Wenyan Fu, Yingdong Ni, Ruqian Zhao
      Tonic immobility (TI) is an innate characteristic of animals related to fear or stress response. Animals can be classified into long TI (LTI) and short TI (STI) phenotypes based on TI test duration. In this study, effect of TI phenotype, chronic corticosterone administration (CORT), and their interaction on cholesterol metabolism in liver was evaluated in broilers. LTI broilers showed higher level of cholesterol in liver compared to STI chickens (p<0.05), and CORT significantly increased hepatic cholesterol content (p<0.01). Real-time PCR results showed that both TI and CORT potentially altered ABCA1 and CYP7A1 gene expressions (0.05<p<0.1), while there was no significant interaction of CORT and TI on both gene expressions. CORT treatment significantly increased the level of SREBP2 (p=0.00), LDLR (p<0.05), GR (p<0.05) and 11β-HSD2 (p<0.05) protein abundance in liver. However, TI phenotype only affected hepatic HMGCR protein expression, and LTI broilers showed higher level of HMGCR protein expression in liver than STI (p<0.05). These results indicate that chronic CORT administration causes hepatic cholesterol accumulation in broiler chickens mainly by enhancing cholesterol synthesis and uptake into liver. LTI chickens had higher amount of total cholesterol in liver, which might be associated with an increase of hepatic HMGCR protein expression. However, there is no interaction between TI and CORT on cholesterol metabolism in liver of broilers.


      PubDate: 2015-10-11T23:55:26Z
       
  • Acclimation of killifish to thermal extremes of hot spring: Transcription
           of gonadal and liver heat shock genes
    • Abstract: Publication date: Available online 11 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Arash Akbarzadeh, Erica H. Leder
      Some killifish species are known to thrive in the thermal extreme of hot springs, and it is likely that they have evolved novel mechanisms to achieve thermal tolerance. In this study, we explored the hypothesis that killifish acclimate to thermal extremes through regulation of genes involved in stress and metabolism. We examined the liver and gonadal transcription of heat shock proteins (hsp70, hsp90ɑ, hsp90b), glucokinase (gck), and high mobility group b1 (hmgb1) protein in wild killifish species from hot springs and rivers using quantitative real-time PCR. Moreover, we exposed a river killifish species Aphanius dispar to a long-term thermal regime of hot spring (37-40°C) and examined the liver transcription of the heat shock genes. Hot spring killifish with temperature 37–40°C showed a significant, strong upregulation of liver hsp90a, while gck mRNA expression was the highest in river killifish. The results of mRNA expression in gonadal (ovary and testis) tissues of male and female killifish showed that the transcripts of both isoforms of hsp90 were much more upregulated in testis of males than ovary of females. Moreover, the testicular transcript levels of hsp90a, hsp90b and hsp70 were higher in hot spring killifish than the river ones. The results of the common garden experiments showed that the transcripts of hsp70, hsp90b and hmgb1were mildly induced (>twofold) at the time when temperature reached to 37-40°C, while the transcripts of the other paralog encoding for hsp90a was strongly induced (17 fold increase). The level of hsp70 and hsp90b transcripts decreased from their initial levels after long-term exposure to elevated temperatures, while hsp90a was dramatically more upregulated when fish were maintained in thermal extreme (42-fold change higher than in ambient temperature). Moreover, liver gck transcript levels were strongly affected by temperature, so that significant downregulation of gck transcripts was observed at the time when temperature was raised to 37-40 °C (80-fold decrease) and during exposure to long term thermal extreme (56-fold decrease). It can be concluded that the regulation of heat shock genes particularly hsp90a might be a key factor of the acclimation of fish to high temperature environments like hot springs.


      PubDate: 2015-10-11T23:55:26Z
       
  • Coronary blood flow in the anesthetized American alligator (Alligator
           mississippiensis)
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Bjarke Jensen, Magnus Elfwing, Ruth M. Elsey, Tobias Wang, Dane A. Crossley
      Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American alligators (Alligator mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressure.


      PubDate: 2015-10-08T08:55:32Z
       
  • Plasma levels of follicle-stimulating and luteinizing hormones during the
           reproductive cycle of wild and cultured Senegalese sole (Solea
           senegalensis)
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): François Chauvigné, Elvira Fatsini, Neil Duncan, Judith Ollé, Silvia Zanuy, Ana Gómez, Joan Cerdà
      The intensive culture of the Senegalese sole (Solea senegalensis) is hampered by the low or null fertilization rates exhibited by the first generation (F1) of reared males. To investigate the regulation of the reproductive processes in this species by the pituitary gonadotropins follicle-stimulating and luteinizing hormones (Fsh and Lh, respectively), we developed a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) for Lh measurements. Quantification of the Fsh and Lh plasma levels in cultured sole using the Lh ELISA developed here, and a previously developed ELISA for Fsh, indicated that in both males and females circulating Fsh steadily increased during autumn and winter and prior to the major spawning in spring, whereas an Lh surge occurred specifically during spawning. The increase in Fsh was associated with a rise of plasma levels of the steroid hormones testosterone (T), 11-ketotestosterone (11-KT) and estradiol-17β (E2), but that of Lh was concomitant with a strong decline of the levels of E2 in females and of 11-KT in males, possibly reflecting a rapid steroidogenic shift promoting the final maturation of gametes. Comparison of the plasma levels of gonadotropins and steroids between wild and F1 fish during autumn and spring revealed that F1 males showed significantly lower plasma Lh titres compared to wild males, whereas the levels of T and 11-KT were similar or more elevated in the F1 fish. These data suggest that an impaired Lh secretion during spawning, and perhaps altered Lh-mediated mechanisms in the testis, may be underlying causes for the low reproductive performance of Senegalese sole F1 males.


      PubDate: 2015-10-08T08:55:32Z
       
  • Energy metabolism of hyperthyroid-induced gilthead sea bream Sparus aurata
           L.
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Luis Vargas-Chacoff, Ignacio Ruiz-Jarabo, Francisco J. Arjona, Raúl Laiz-Carrión, Gert Flik, Peter H.M. Klaren, Juan M. Mancera
      Thyroid hormones, in particular 3,5,3′-triiodothyronine or T3, are involved in multiple physiological processes in mammals such as protein, fat and carbohydrate metabolism. However, the metabolic actions of T3 in fish are still not fully elucidated. We therefore tested the effects of T3 on Sparus aurata energy metabolism and osmoregulatory system, a hyperthyroid-induced model that was chosen. Fish were implanted with coconut oil depots (containing 0, 2.5, 5.0 and 10.0μgT3/g body weight) and sampled at day 3 and 6 post-implantation. Plasma levels of free T3 as well as glucose, lactate and triglyceride values increased with increasing doses of T3 at days 3 and 6 post-implantation. Changes in plasma and organ metabolite levels (glucose, glycogen, triglycerides, lactate and total α amino acid) and enzyme activities related to carbohydrate, lactate, amino acid and lipid pathways were detected in organs involved in metabolism (liver) and osmoregulation (gills and kidney). Our data implicate that the liver uses amino acids as an energy source in response to the T3 treatment, increasing protein catabolism and gluconeogenic pathways. The gills, the most important extruder of ammonia, are fuelled not only by amino acids, but also by lactate. The kidney differs significantly in its substrate preference from the gills, as it obtained metabolic energy from lactate but also from lipid oxidation processes. We conclude that in S. aurata lipid catabolism and protein turnover are increased as a consequence of experimentally induced hyperthyroidism, with secondary osmoregulatory effects.


      PubDate: 2015-10-08T08:55:32Z
       
  • Heat and oxidative stress alter the expression of orexin and its related
           receptors in avian liver cells
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Elizabeth Greene, Stephanie Khaldi, Peter Ishola, Walter Bottje, Takeshi Ohkubo, Nicholas Anthony, Sami Dridi
      Orexins (A and B) or hypocretins (1 and 2) are hypothalamic orexigenic neuropeptides that are involved in the regulation of several physiological processes in mammals. Recently, orexin has been shown to activate the hypothalamic-pituitary-adrenal (HPA) stress axis and emerging evidences identify it as a stress modulator in mammals. However, the regulation of orexin system by stress itself remains unclear. Here, we investigate the effects of heat, 4-Hydroxynonenal (4-HNE) and hydrogen peroxide (H2O2) stress on the hepatic expression of orexin (ORX) and its related receptors (ORXR1/2) in avian species. Using in vivo and in vitro models, we found that heat stress significantly down-regulated ORX and ORXR1/2 mRNA and protein abundances in quail liver and LMH cells. H2O2, however, decreased ORX protein and increased ORX mRNA levels in a dose dependent manner (P <0.05). The absence of correlation between orexin mRNA and protein levels suggests that H2O2 treatment modulates post-transcriptional mechanisms. 4-HNE had a biphasic effect on orexin system expression, with a significant up-regulation at low doses (10 and 20μM) and a significant down-regulation at a high dose (30μM). Taken together, our data indicated that hepatic orexin system could be a molecular signature in the heat and oxidative stress response.


      PubDate: 2015-10-08T08:55:32Z
       
  • Dietary glutamine supplementation effects on amino acid metabolism,
           intestinal nutrient absorption capacity and antioxidant response of
           gilthead sea bream (Sparus aurata) juveniles
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): F. Coutinho, C. Castro, E. Rufino-Palomares, B. Ordóñez-Grande, M.A. Gallardo, A. Oliva-Teles, H. Peres
      A study was undertaken to evaluate dietary glutamine supplementation effects on gilthead sea bream performance, intestinal nutrient absorption capacity, hepatic and intestinal glutamine metabolism and oxidative status. For that purpose gilthead sea bream juveniles (mean weight 13.0g) were fed four isolipidic (18% lipid) and isonitrogenous (43% protein) diets supplemented with 0, 0.5, 1 and 2% glutamine for 6weeks. Fish performance, body composition and intestinal nutrient absorption capacity were not affected by dietary glutamine levels. Hepatic and intestinal glutaminase (GlNase), glutamine synthetase (GSase), alanine aminotransferase, aspartate aminotransferase and glutamate dehydrogenase activities were also unaffected by dietary glutamine supplementation. In the intestine GlNase activity was higher and GSase/GlNase ratio was two-fold lower than in the liver, suggesting a higher use of glutamine for energy production by the intestine than by the liver. The liver showed higher catalase and glucose-6-phosphate dehydrogenase activities, while the intestine presented higher glutathione peroxidase and glutathione reductase activities and oxidised glutathione content, which seems to reveal a higher glutathione dependency of the intestinal antioxidant response. Total and reduced glutathione contents in liver and intestine and superoxide dismutase activity in the intestine were enhanced by dietary glutamine, though lipid peroxidation values were not affected. Overall, differences between liver and intestine glutamine metabolism and antioxidant response were identified and the potential of dietary glutamine supplementation to gilthead sea bream's antioxidant response was elucidated.


      PubDate: 2015-10-08T08:55:32Z
       
  • Brain size and thermoregulation during the evolution of the genus Homo
    • Abstract: Publication date: Available online 3 October 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Daniel E. Naya, Hugo Naya, Enrique P. Lessa
      Several hypotheses have been proposed to explain the evolution of an energetically costly brain in the genus Homo. Some of these hypotheses are based on the correlation between climatic factors and brain size recorded for this genus during the last millions of years. In this study, we propose a complementary climatic hypothesis that is based on the mechanistic connection between ambient temperature, thermoregulatory costs, and size of internal organs that exist in endothermic species. Specifically, we hypothesized that global cooling during the last 3.2 my may have imposed an increased energy expenditure for thermoregulation, which in the case of hominids could represent an evolutionary driver for the evolution of an expanded, heat generating brain, or, at the very least, it could imply the relaxation of a negative selection pressure acting upon the size of this energetically expensive organ. To test this idea, here we (1) assess variation in the energetic costs of thermoregulation and brain maintenance for the last 3.2 my, and (2) evaluate the relationship between Earth temperature and brain maintenance cost for the same period, taking into account the effects of body mass and fossil age. We found that: (1) the increase in thermoregulatory costs is greater than those associated with brain enlargement, and, at the same time, the energetic cost associated with brain enlargement represent an important fraction (between 47.5% and 82.5%) of the increase in energy needed for thermoregulation; (2) fossil age is a better predictor of brain maintenance cost than Earth temperature, suggesting that (at least) another factor correlated with time was more relevant than ambient temperature in brain size evolution; and (3) there is a significant negative correlation between the energetic cost of brain and Earth temperature, even after accounting for the effect of body mass and fossil age. Thus, our results expand the current energetic framework for the study of brain size evolution in our lineage by suggesting that the fall in Earth temperature that occurred during the last millions of years may have facilitated brain enlargement.


      PubDate: 2015-10-08T08:55:32Z
       
  • Field studies on the annual activity and the metabolic responses of a land
           snail population living in high altitude
    • Abstract: Publication date: January 2016
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 191
      Author(s): Alexandra Staikou, George Tachtatzis, Konstantinos Feidantsis, Basile Michaelidis
      In the context of the metabolic cold adaptation hypothesis (MCA), we investigated a) the life and activity cycle characteristics and b) the metabolic responses of the endemic land snail species Cattania trizona olympica living at 1100m altitude in Olympus mountain (Greece). Field observations on the annual activity cycle of C. trizona olympica revealed that snails' activity was restricted mainly between the end of May and September, when the higher temperatures were recorded, while first matings were recorded in July and the last ones in mid September indicating a restricted favorable time period for reproduction. The activities of enzymes of intermediate metabolism showed a periodic seasonal pattern of change which seems to be closely related to the pattern of annual changes of air temperature and most of them exhibited higher activities during the coldest and warmest periods of the year. Moreover the data indicate a distinct differentiation of fuel oxidation during arousal and reproductive periods with lipid oxidation, apart from carbohydrates, contributing significantly to ATP turnover during reproductive activity. The higher enzymatic activities, determined in the tissues of C. trizona olympica than the corresponding ones determined in the tissues of the land snail species living at low altitudes, might indicate higher sensitivity of the intermediate metabolism and ATP turnover in C. trizona olympica to changes in environmental factors. Although the latter seems to be in line with the MCA hypothesis, it needs further investigation on metabolic rates to support it.


      PubDate: 2015-10-03T08:45:24Z
       
 
 
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