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BIOCHEMISTRY (197 journals)                  1 2     

AAPS PharmSciTech     Hybrid Journal   (Followers: 6)
Acetic Acid Bacteria     Open Access   (Followers: 1)
ACS Chemical Biology     Full-text available via subscription   (Followers: 287)
ACS Chemical Neuroscience     Full-text available via subscription   (Followers: 13)
Acta Crystallographica Section D : Biological Crystallography     Hybrid Journal   (Followers: 9)
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Advances and Applications in Bioinformatics and Chemistry     Open Access   (Followers: 7)
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Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 10)
African Journal of Biochemistry Research     Open Access  
African Journal of Chemical Education     Open Access   (Followers: 1)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 4)
American Journal of Biochemistry     Open Access   (Followers: 6)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 165)
American Journal of Biochemistry and Molecular Biology     Open Access   (Followers: 11)
American Journal of Polymer Science     Open Access   (Followers: 17)
Amino Acids     Hybrid Journal   (Followers: 7)
Analytical Biochemistry     Hybrid Journal   (Followers: 192)
Annals of Clinical Biochemistry     Hybrid Journal   (Followers: 1)
Annual Review of Biochemistry     Full-text available via subscription   (Followers: 28)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
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Applied Organometallic Chemistry     Hybrid Journal   (Followers: 4)
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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)
Avicenna Journal of Medical Biochemistry     Open Access  
Bangladesh Journal of Medical Biochemistry     Open Access   (Followers: 2)
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Biochemistry (Moscow)     Hybrid Journal   (Followers: 3)
Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology     Hybrid Journal   (Followers: 4)
Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry     Hybrid Journal   (Followers: 3)
Biochemistry and Cell Biology     Full-text available via subscription   (Followers: 9)
Biochemistry and Molecular Biology Education     Hybrid Journal   (Followers: 3)
Biochemistry and Molecular Biology of Fishes     Full-text available via subscription   (Followers: 1)
Biochemistry Research International     Open Access   (Followers: 4)
Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids     Hybrid Journal   (Followers: 3)
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease     Hybrid Journal   (Followers: 18)
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research     Hybrid Journal   (Followers: 5)
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BMC Chemical Biology     Open Access   (Followers: 4)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Cell Biochemistry and Biophysics     Hybrid Journal   (Followers: 6)
Cell Biochemistry and Function     Hybrid Journal   (Followers: 3)
Cellular Physiology and Biochemistry     Open Access   (Followers: 3)
Central European Journal of Chemistry     Hybrid Journal   (Followers: 5)
ChemBioChem     Hybrid Journal   (Followers: 2)
Chemical and Biological Technologies for Agriculture     Open Access  
Chemical Biology & Drug Design     Hybrid Journal   (Followers: 23)
Chemical Engineering Journal     Hybrid Journal   (Followers: 18)
Chemical Senses     Hybrid Journal   (Followers: 1)
Chemical Speciation and Bioavailability     Full-text available via subscription   (Followers: 1)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 2)
Chemistry & Biodiversity     Hybrid Journal   (Followers: 5)
Chemistry & Biology     Full-text available via subscription   (Followers: 16)
Chemistry and Ecology     Hybrid Journal   (Followers: 1)
Clinical Biochemist Reviews     Full-text available via subscription   (Followers: 1)
Clinical Biochemistry     Hybrid Journal   (Followers: 3)
Clinical Chemistry and Laboratory Medicine     Full-text available via subscription   (Followers: 3)
Clinical Lipidology     Full-text available via subscription  
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology     Hybrid Journal   (Followers: 5)
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology     Hybrid Journal   (Followers: 4)
Comparative Biochemistry and Physiology Part D: Genomics and Proteomics     Hybrid Journal   (Followers: 3)
Comprehensive Biochemistry     Full-text available via subscription   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Critical Reviews in Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 2)
Current Chemical Biology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Biology     Hybrid Journal   (Followers: 14)
Current Opinion in Lipidology     Hybrid Journal   (Followers: 2)

        1 2     

Journal Cover Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
   Journal TOC RSS feeds Export to Zotero [7 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1095-6433
     Published by Elsevier Homepage  [2570 journals]
  • Baroreflex function in anurans from different environments
    • Abstract: Publication date: Available online 16 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Michael S. Hedrick , Kadi A. McNew , Dane A. Crossley II
      Anurans from terrestrial environments have an enhanced ability to maintain arterial blood pressure through lymph mobilization in response to desiccation or hemorrhage compared with semiaquatic or aquatic species. Because short term blood pressure homeostasis is regulated by arterial baroreceptors, we compared baroreflex function in three species of anurans that span a range of environments, dehydration tolerance and an ability to maintain arterial blood pressure with dehydration and hemorrhage. The cardiac limb of the baroreflex loop was studied using pharmacological manipulation of blood pressure with phenylephrine and sodium nitroprusside (20-200μgkg-1 each), and the resulting changes in heart rate were quantitatively analyzed using a four-parameter sigmoidal logistic function. Resting arterial blood pressure in the aquatic species, Xenopus laevis, was 3.6±0.3 kPa and was significantly less (P<0.005) than for the semiaquatic species, Lithobates catesbeianus (4.1±0.2 kPa), or the terrestrial species, Rhinella marina (4.7±0.2 kPa). Resting heart rates were equivalent in all three species. The maximal baroreflex gain was not different among the three species and ranged from 12.1 to 14.3 beats min-1 kPa-1 and occurred at mean arterial pressures (Pm) ranging from 3.0 to 3.8 kPa, which were slightly below the resting arterial blood pressures for each species. Mean arterial blood pressures at rest in the three species were near the saturation point of the baroreflex curve which provides the animals with a greater heart rate response range to hypotensive, rather than hypertensive, changes in blood pressure. This is consistent with the hypothesis that arterial baroreceptors are key sensory components that allow anurans to maintain arterial blood pressure possibly by mobilization of lymphatic return in response to hypotension.

      PubDate: 2014-10-17T10:00:22Z
  • mRNA levels of kisspeptins, kisspeptin receptors, and GnRH1 in the brain
           of chub mackerel during puberty
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Hirofumi Ohga , Hayato Adachi , Kojiro Matsumori , Ryoko Kodama , Mitsuo Nyuji , Sethu Selvaraj , Keitaro Kato , Shinji Yamamoto , Akihiko Yamaguchi , Michiya Matsuyama
      Kisspeptin (Kiss) and its cognate receptor (Kiss1R), implicated in the neuroendocrine control of GnRH secretion in mammals, have been proposed to be the key factors in regulating puberty. However, the mechanisms underlying the initiation of puberty in fish are poorly understood. The chub mackerel Scomber japonicus expresses two forms of Kiss (kiss1 and kiss2) and two Kiss receptor (kissr1 and kissr2) genes in the brain, which exhibit sexually dimorphic changes during the seasonal reproductive cycle. This indicates that the kisspeptin system plays an important role in gonadal recrudescence of chub mackerel; however, the involvement of the kisspeptin system in the pubertal process has not been identified. In the present study, we examined the mRNA expression of kiss1, kiss2, kissr1, kissr2, and gnrh1 (hypophysiotropic form) in the brain of a chub mackerel during puberty. In male fish, kiss2, kissr1 and kissr2 levels increased significantly at 14weeks post-hatch (wph), synchronously with an increase in type A spermatogonial populations in the testis; kiss2 and gnrh1 levels significantly increased at 22wph, just before the onset of meiosis in the testes. In female fish, kiss2 increased significantly at 14wph, synchronously with an increase in the number of perinucleolar oocytes in the ovary; kiss1 and kiss2 levels significantly increased concomitantly with an increase in the kissr1, kissr2, and gnrh1 levels at 24wph, just before the onset of vitellogenesis in oocytes. The present results suggest positive involvement of the kisspeptin–GnRH system in the pubertal process in the captive reared chub mackerel.

      PubDate: 2014-10-12T15:04:10Z
  • Seasonal variation in body mass, body temperature and thermogenesis in the
           Hwamei, Garrulax canorus
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Mei-Xiu Wu , Li-Meng Zhou , Li-Dan Zhao , Zhi-Jun Zhao , Wei-Hong Zheng , Jin-Song Liu
      The basal thermogenesis of birds is beginning to be viewed as a highly flexible physiological trait influenced by environmental fluctuations, particularly changes in ambient temperature (T a). Many birds living in regions with seasonal fluctuations in T a typically respond to cold by increasing their insulation and adjusting their metabolic rate. To understand these metabolic adaptations, body temperature (T b), metabolic rate (MR), thermal neutral zone (TNZ) and thermal conductance were measured within a range of temperatures from 5 to 40°C in free-living Hwamei, Garrulax canorus, in both winter and summer. Body mass was 61.2±0.3g in winter and 55.5±1.0g in summer, and mean T b was 41.6±0.1°C in winter and 42.3±0.1°C in summer. TNZ was between 28.3 and 35.1°C in winter and between 28.7 and 33.2°C in summer. The mean basal metabolic rate (BMR) within TNZ was 203.32±11.81ml O2 h−1 in winter and 168.99±6.45ml O2 h−1 in summer. Minimum thermal conductance was 3.73±0.09joulesg−1 h−1 °C−1 in winter and 3.26±0.06joulesg−1 h−1 °C−1 in summer. Birds caught in winter had higher body mass, MR, and more variable TNZ than those in summer. The increased winter BMR indicates improved ability to cope with cold and maintenance of a high T b. These results show that the Hwamei's metabolism is not constant, but exhibits pronounced seasonal phenotypic flexibility associated with maintenance of a high T b.

      PubDate: 2014-10-12T15:04:10Z
  • Detection of long-term influence of prenatal temperature stimulation on
           hypothalamic type-II iodothyronine deiodinase in juvenile female broiler
           chickens using a novel immunohistochemical amplification protocol
    • Abstract: Publication date: Available online 5 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Maaly Nassar , Ingrid Halle , Andreas Plagemann , Barbara Tzschentke
      It has been clearly shown that early environmental stimulation may have long-lasting influence on body functions. Because of the strong relationship between thermoregulation and other homeostatic linked physiological parameters, perinatal thermal manipulation will have also impact on other body functions like reproduction. As a maturation stimulant for later reproductive performance, hypothalamic type-2 iodothyronine deiodinase (Dio2) expression was investigated in 35 days old immature female broilers with and without embryonic temperature stimulation. For the first time, human-specific Dio2 primary antibodies combined with additional amplification enabled the immunohistochemical detection of hypothalamic Dio2 protein in birds. The novel protocol includes an additional amplification step involving swine-anti-rabbit/mouse/goat antibodies against both goat anti-Dio2 primary and rabbit anti-goat biotinylated secondary commercial antibodies in the standard diaminobenzidine protocol. But, significant Dio2 expression was exclusively found in perinatally short-term temperature stimulated hens. Caudal but not rostral hypothalamic slices revealed that elevating incubation temperature 1°C for 2 h daily, from day 18 of embryonic development until hatching, induced a statistical significant expression of Dio2 within the subcommisural organ and the median eminence. This ample expression of Dio2 protein within caudal but not rostral hypothalamic slices of embryonic temperature stimulated chickens, leads to the assumption of a novel physiological prospective for embryonic thermal manipulation involving the suppression of thyroid hormone and the boosting of hypothalamic Dio2-induced FSH secretion to considerably advance the age of photoinduced egg production. It could be also of practicable relevance for broiler breeder females, and needs further investigations.

      PubDate: 2014-10-08T14:27:11Z
  • Short-term effects of cortisol implantation on blood biochemistry and
           thyroid hormones in previtellogenic great sturgeon Huso huso
    • Abstract: Publication date: Available online 5 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Samaneh Poursaeid , Bahram Falahatkar , Glen Van Der Kraak
      This study examined the effects of implanted cortisol on various aspects of intermediary metabolism of great sturgeon, Huso huso. Prior to experimentation all fish received a one-cm posterior-anterior incision in the ventral wall and were examined using an endoscope to observe the state of the development of the ovary. Subsequently, the 3-year-old female fish in the previtellogenic stage (mean body weight 6759±53.2g) were intraperitoneally implanted with a cocoa butter pellet containing cortisol to mimic the effects of chronic stress. The implant doses were 0 (C0; as control), 5 (C5) and 50 (C50) mg cortisol/kg body weight. Blood samples were taken every seven days during the four weeks of the experiment and analyzed for cortisol, glucose, adrenocorticotropic hormone (ACTH), total protein, total lipid, triiodothyronine (T3), thyroxine (T4), cholesterol and triglyceride content. Growth was reduced in all experimental groups and was not affected by cortisol treatment. Surprisingly, serum cortisol levels were higher in the C5 group than in the C50 throughout the experiment. A significant increase in glucose levels was observed in the cortisol-implanted fish from day 14 onwards. The high dose of cortisol elicited a significant increase in serum T3 and T4 levels. Fish implanted with the high cortisol dose also showed increases in serum ACTH, total lipid and cholesterol levels throughout a 28-day experimental period. The present study reveals that the negative effects of endoscopic surgery remains for at least four weeks and that a sustained-release implant of cortisol to mimic the effects of chronic stress affects metabolic responses in terms of altered glucose, ACTH, T3, total lipid and cholesterol concentrations. Since the adverse effects of endoscopic surgery on sturgeon welfare can be amplified by cortisol, special attention should be paid to the potential effects of chronic stress of sturgeon in culture.

      PubDate: 2014-10-08T14:27:11Z
  • Huddling reduces evaporative water loss in torpid Natterer’s bats,
           Myotis nattereri
    • Abstract: Publication date: Available online 5 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jan S. Boratyński , Craig K.R. Willis , Małgorzata Jefimow , Michał S. Wojciechowski
      Periodic arousals during hibernation consume most of the winter energy budget for hibernating mammals. Evaporative water loss (EWL) is thought to affect the frequency of arousals and thus energy balance might have dramatic implications for over-winter survival and fitness. We hypothesized that huddling affects EWL and energy expenditure in torpid mammals. We tested this hypothesis using bats as a model and predicted that, during torpor, EWL and energy expenditure of huddling individuals would be lower than in individuals that are not in a huddle. We measured EWL and metabolic rate of torpid Myotis nattereri (Kuhl, 1817) huddling in groups or roosting individually. Evaporative water loss in huddling individual bats was almost 30% lower than in solitary animals (P =0.03), even after correcting for the effects of metabolic rate. Our results suggest that conservation of water is a substantial benefit underlying huddling by bats during hibernation. Ultimately, huddling could reduce the total cost of hibernation by reducing the number of expensive periodic arousals from torpor caused by the need to supplement water.

      PubDate: 2014-10-08T14:27:11Z
  • Sequence, genomic organization and expression of ghrelin receptor in grass
           carp, Ctenopharyngodon idellus
    • Abstract: Publication date: January 2015
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 179
      Author(s): Wen-jing Cai , Xiao-chen Yuan , Yong-chao Yuan , Shou-qi Xie , Yuan Gong , Hang Su , Yang Qiao
      The growth hormone secretagogue-receptor (GHS-R) is an endogenous receptor for the gut hormone ghrelin. Here we report the identification and characterization of GHS-R1a in grass carp, Ctenopharyngodon idellus. The full-length GHS-R1a cDNA contained a 1803-bp coding domain sequence which encoded a peptide of 360 amino acid residues. Comparison analysis revealed that the amino acid sequences of GHS-R1a were highly conserved in vertebrates and shared 97% amino acid identity with zebrafish (Danio rerio), 96% with jian carp (Cyprinus carpio var. Jian) and 93% with goldfish (Carassius auratus). The GHS-R1a showed the highest level of mRNA expression in the pituitary, followed by the brain and liver, and the lowest expression was observed in the hindgut. Intraperitoneally injected with grass carp ghrelin (50, 100 and 150ng/g body weight (BW)), grass carp showed greater mRNA expression of GHS-R1a in the pituitary compared with saline injected at 0.5h postinjection. It was observed that food deprivation could promote the expression of ghrelin and GHS-R1a in the pituitary, demonstrating that nutritional status can influence the expression of both ghrelin and GHS-R1a in the pituitary. After a 2- or 4-week fast, plasma growth hormone (GH) increased, was positively correlated with ghrelin and GHS-R1a mRNA expression levels in the pituitary. These results suggested that the involvement of ghrelin/GHS-R1a systems in mediating the effects of nutritional status and ghrelin on growth processes in grass carp.

      PubDate: 2014-10-08T14:27:11Z
  • Temperature effects on baroreflex control of heart rate in the toad,
           Rhinella schneideri
    • Abstract: Publication date: Available online 28 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Lucas A. Zena , Luciane H. Gargaglioni , Kênia C. Bícego
      For an adequate blood supply to support metabolic demands, vertebrates regulate blood pressure to maintain sufficient perfusion to avoid ischemia and other tissue damage like edema. Using a pharmacological approach (phenylephrine and sodium nitroprusside) we investigated baroreflex sensitivity at 15, 25, and 30°C in toads Rhinella schneideri. Baroreflex sensitivity presented a high thermal dependence (Q10 =1.9–4.1), and the HR–baroreflex curve was shifted up and to the right as temperature increased from 15 to 30°C. Baroreflex variables, namely, HR range, gain 50 (maximal gain) and normalized gain 50 increased 206, 235, and 160% from 15 to 30°C, respectively. The cardiac limb of the baroreflex response to pharmacological treatments was significantly blunted after full autonomic blockade. In addition, there was a clear baroreflex–HR response mainly to hypotension at all three temperatures tested. These findings indicate that toads present temperature dependence for cardiac limb of the barostatic response and the cardiac baroreflex response in R. schneideri is primarily hypotensive rather than hypertensive as well as crocodilians and mammals. Thus, the cardiac baroreflex compensation to changes in arterial pressure might present different patterns among amphibian species, since the previously reported bradycardic compensation to hypertension in some anurans was not observed in the toad used in the present study.

      PubDate: 2014-10-03T12:34:11Z
  • Diets labelled with 13C-starch and 15N-protein reveal daily rhythms of
           nutrient use in gilthead sea bream (Sparus aurata)
    • Abstract: Publication date: Available online 28 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Olga Felip , Josefina Blasco , Antoni Ibarz , Miguel Martín-Pérez , Jaume Fernández-Borràs
      Almost all functions in animals rely on daily rhythms, and mealtime can act as a rhythm-marker of nutrients assimilation and use. The aim of this research was to determine the effects of meal timing and food composition on carbohydrate use and protein retention of gilthead sea bream. Three groups of fish were fed twice a day (at 10am and at 5pm) for two months with two alternating diets: a commercial diet (Cd) and a high-carbohydrate, low-protein diet (Ed). The Ed/Cd group received the Ed diet in the morning and the Cd diet in the afternoon, and the Cd/Ed group received these diets in the reverse order. The Cd/Cd group only received the commercial diet (control group). After 56days of the feeding period, two force-feeding experiments (PF1 and PF2 for all three groups) measured the fate of a single meal labelled with 15N-protein and 13C-starch through the retention of both isotopes in the main organs and tissue reserves. In PF1 fish were fed at 10am (morning mealtime), and in PF2 at 5pm (afternoon mealtime). Fish were sampled at the next two mealtimes (PF1: 7 and 24h post-feeding, PF2: 17 and 24h post-feeding). Recovery of the labelled nutrients differed according to, first, the dietary regime, and second, the last meal received (Cd or Ed). Although the fish in the regimes with Ed diet received less protein each day, they compensated with higher protein retention combined with more use of carbohydrates for energy. Nevertheless, carbohydrates were not used as efficiently in the afternoon as in the morning. So, the use of carbohydrate for energy production and protein for growth can be improved by adjusting diet composition and mealtime.

      PubDate: 2014-10-03T12:34:11Z
  • Vasodilatory effects of homologous adrenomedullin 2 and adrenomedullin 5
           in isolated blood vessels of two species of eel
    • Abstract: Publication date: Available online 2 October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Melissa S. Cameron , Shigenori Nobata , Yoshio Takei , John A. Donald
      In mammals, adrenomedullin (AM) is a potent vasodilator through signalling pathways that involve the endothelium. In teleost fishes, a family of five AMs are present (AM1/4, AM2/3 and AM5) with four homologous AMs (AM1, AM2/3 and AM5) recently cloned from the Japanese eel, Anguilla japonica. Both AM2 and AM5 have been shown to be strong in vivo vasodepressors in eel, but the mechanism of action of homologous AMs on isolated blood vessels has not been examined in teleost fish. In this study, both eel AM2 and AM5 caused a marked vasodilation of the dorsal aorta. However, only AM5 consistently dilated the small gonadial artery in contrast to AM2 that had no effect in most preparations. Neither AM2 nor AM5 had any effect when applied to the first afferent branchial artery; in contrast, eel ANP always caused a large vasodilation of the branchial artery. In the dorsal aorta, indomethacin significantly reduced the AM2 vasodilation, but had no effect on the AM5 vasodilation. In contrast, removal of the endothelium significantly enhanced the AM5 vasodilation only. In the gonadial artery, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) significantly reduced the AM5 vasodilation suggesting a role for soluble guanylyl cyclase in the dilation, but L-NNA and removal of the endothelium had no effect. The results of this study indicate that AM2 and AM5 have distinct vasodilatory effects that may be due to the peptides signalling via different receptors to regulate vascular tone in eel.

      PubDate: 2014-10-03T12:34:11Z
  • The effect of temperature and body size on metabolic scope of activity in
           juvenile Atlantic cod Gadus morhua L.
    • Abstract: Publication date: Available online 30 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Bjørn Tirsgaard , Jane W. Behrens , John F. Steffensen
      Changes in ambient temperature affect the physiology and metabolism and thus the distribution of fish. In this study we used intermittent flow respirometry to determine the effect of temperature (2, 5, 10, 15 and 20°C) and wet body mass (BM) (~30–460g) on standard metabolic rate (SMR, mgO2 h−1), maximum metabolic rate (MMR, mgO2 h−1) and metabolic scope (MS, mgO2 h−1) of juvenile Atlantic cod. SMR increased with BM irrespectively of temperature, resulting in an average scaling exponent of 0.87 (0.82–0.92). Q10 values were 1.8–2.1 at temperatures between 5 and 15°C but higher (2.6–4.3) between 2 and 5°C and lower (1.6–1.4) between 15 and 20°C in 200 and 450g cod. MMR increased with temperature in the smallest cod (50g) but in the larger cod MMR plateaued between 10, 15 and 20°C. This resulted in a negative correlation between the optimal temperature for MS (Topt) and BM, Topt being respectively 14.5, 11.8 and 10.9°C in a 50, 200 and 450g cod. Irrespective of BM cold water temperatures resulted in a reduction (30–35%) of MS whereas the reduction of MS at warm temperatures was only evident for larger fish (200 and 450g), caused by plateauing of MMR at 10°C and above. Warm temperatures thus seem favourable for smaller (50g) juvenile cod, but not larger for conspecifics (200 and 450g).

      PubDate: 2014-10-03T12:34:11Z
  • Life stage-related differences in fatty acid composition of an obligate
           ectoparasite, the deer ked (Lipoptena cervi)—Influence of blood
           meals and gender
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anne-Mari Mustonen , Reijo Käkelä , Tommi Paakkonen , Petteri Nieminen
      Metamorphosis and diet often influence fatty acid (FA) signatures (FAS) of insects. We investigated FAS in a hematophagous ectoparasite, the deer ked (Lipoptena cervi). Deer keds shed their wings upon attachment on the host and, thus, the FAS of an individual blood-fed imago/pupa in the fur of its host can be traced back to the blood FA profile of a single moose (Alces alces). Host blood and different life stages of deer keds were investigated for FA by gas chromatography. The FAS of life stages resembled each other more closely than the diet. Blood meals modified the FAS of both sexes but the FAS of the blood-fed females were closer to those of the prepupae/pupae. The parasitizing males had higher proportions of major saturated FA (SFA) and polyunsaturated FA (PUFA) than the females, which contained more monounsaturated FA (MUFA) with higher ratios of n-3/n-6 PUFA and unsaturated FA (UFA)/SFA. The proportions of 16:1n-7 were <1% in the blood but 18% (males) and 29% (females) in the blood-fed keds. Allocation of lipids to offspring by the females and possible accumulation of PUFA in male reproductive organs may have induced these sex-related differences. MUFA percentages and UFA/SFA ratios increased while SFA and many PUFA decreased from the reproducing females to the pupae. The diapausing pupae displayed lowered n-3/n-6 PUFA ratios and could have mobilized 16:0 and 18:3n-3 for the most fundamental metabolic processes. In conclusion, FAS are modified through the life stages of the deer ked possibly due to their different requirements.

      PubDate: 2014-09-20T08:14:15Z
  • Taking their breath away: Metabolic responses to low-oxygen levels in
           anchialine shrimps (Crustacea: Atyidae and Alpheidae)
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Justin C. Havird , Rebecca C. Vaught , Jeffrey R. Weeks , Yoshihisa Fujita , Michio Hidaka , Scott R. Santos , Raymond P. Henry
      Crustaceans generally act as oxy-regulators, maintaining constant oxygen uptake as oxygen partial pressures decrease, but when a critical low level is reached, ventilation and aerobic metabolism shut down. Cave-adapted animals, including crustaceans, often show a reduced metabolic rate possibly owing in part to the hypoxic nature of such environments. However, metabolic rates have not been thoroughly explored in crustaceans from anchialine habitats (coastal ponds and caves), which can experience variable oxygenic regimes. Here, an atypical oxy-conforming pattern of oxygen uptake is reported in the Hawaiian anchialine atyid Halocaridina rubra, along with other unusual metabolic characteristics. Ventilatory rates are near-maximal in normoxia and did not increase appreciably as PO2 declined, resulting in a decline in VO2 during progressive hypoxia. Halocaridina rubra maintained in anoxic waters survived for seven days (the duration of the experiment) with no measureable oxygen uptake, suggesting a reliance on anaerobic metabolism. Supporting this, lactate dehydrogenase activity was high, even in normoxia, and oxygen debts were quickly repaid by an unusually extreme increase in oxygen uptake upon exposure to normoxia. In contrast, four related anchialine shrimp species from the Ryukyu Islands, Japan, exhibited physiological properties consistent with previously studied crustaceans. The unusual respiratory patterns found in H. rubra are discussed in the context of a trade-off in gill morphology for osmoregulatory ion transport vs. diffusion of respiratory gasses. Future focus on anchialine species may offer novel insight into the diversity of metabolic responses to hypoxia and other physiological challenges experienced by crustaceans.

      PubDate: 2014-09-20T08:14:15Z
  • Editorial Board
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178

      PubDate: 2014-09-20T08:14:15Z
  • Critical windows in embryonic development: Shifting incubation
           temperatures alter heart rate and oxygen consumption of Lake Whitefish
           (Coregonus clupeaformis) embryos and hatchlings
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): J. Eme , C.A. Mueller , R.G. Manzon , C.M. Somers , D.R. Boreham , J.Y. Wilson
      Critical windows are periods of developmental susceptibility when the phenotype of an embryonic, juvenile or adult animal may be vulnerable to environmental fluctuations. Temperature has pervasive effects on poikilotherm physiology, and embryos are especially vulnerable to temperature shifts. To identify critical windows, we incubated whitefish embryos at control temperatures of 2°C, 5°C, or 8°C, and shifted treatments among temperatures at the end of gastrulation or organogenesis. Heart rate (fH) and oxygen consumption (V. o 2) were measured across embryonic development, and V. o 2 was measured in 1day-old hatchlings. Thermal shifts, up or down, from initial incubation temperatures caused persistent changes in fH and V. o 2 compared to control embryos measured at the same temperature (2°C, 5°C, or 8°C). Most prominently, when embryos were measured at organogenesis, shifting incubation temperature after gastrulation significantly lowered V. o 2 or fH. Incubation at 2°C or 5°C through gastrulation significantly lowered V. o 2 (42% decrease) and fH (20% decrease) at 8°C, incubation at 2°C significantly lowered V. o 2 (40% decrease) and fH (30% decrease) at 5°C, and incubation at 5°C and 8°C significantly lowered V. o 2 at 2°C (27% decrease). Through the latter half of development, V. o 2 and fH in embryos were not different from control values for thermally shifted treatments. However, in hatchlings measured at 2°C, V. o 2 was higher in groups incubated at 5°C or 8°C through organogenesis, compared to 2°C controls (43 or 65% increase, respectively). Collectively, these data suggest that embryonic development through organogenesis represents a critical window of embryonic and hatchling phenotypic plasticity. This study presents an experimental design that identified thermally sensitive periods for fish embryos.

      PubDate: 2014-09-20T08:14:15Z
  • Effects of salinity on metabolic rate and branchial expression of genes
           involved in ion transport and metabolism in Mozambique tilapia
           (Oreochromis mossambicus)
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Aris Zikos , Andre P. Seale , Darren T. Lerner , E. Gordon Grau , Keith E. Korsmeyer
      This study investigated the effects of two rearing salinities, and acute salinity transfer, on the energetic costs of osmoregulation and the expression of metabolic and osmoregulatory genes in the gill of Mozambique tilapia. Using automated, intermittent-flow respirometry, measured standard metabolic rates (SMRs) of tilapia reared in seawater (SW, 130mgO2 kg−1 h−1) were greater than those reared in fresh water (FW, 103mgO2 kg−1 h−1), when normalized to a common mass of 0.05kg and at 25±1°C. Transfer from FW to 75% SW increased SMR within 18h, to levels similar to SW-reared fish, while transfer from SW to FW decreased SMR to levels similar to FW-reared fish. Branchial gene expression of Na+–K+–2Cl− cotransporter (NKCC), an indicator of SW-type mitochondria-rich (MR) cells, was positively correlated with SMR, while Na+–Cl− cotransporter (NCC), an indicator of FW-type MR cells, was negatively correlated. Principal Components Analysis also revealed that branchial expression of cytochrome c oxidase subunit IV (COX-IV), glycogen phosphorylase (GP), and a putative mitochondrial biogenesis regulator in fish, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), were correlated with a higher SMR, plasma osmolality, and environmental salinity, while expression of glycogen synthase (GS), PGC-1β, and nuclear respiratory factor 1 (NRF-1) had negative correlations. These results suggest that the energetic costs of osmoregulation are higher in SW than in FW, which may be related to the salinity-dependent differences in osmoregulatory mechanisms found in the gills of Mozambique tilapia.

      PubDate: 2014-09-20T08:14:15Z
  • Kisspeptin regulates the somatic growth-related factors of the cinnamon
           clownfish Amphiprion melanopus
    • Abstract: Publication date: Available online 15 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Na Na Kim , Young-Ung Choi , Heung-Sik Park , Choi Cheol Young Choi
      This study aimed to test the effects of kisspeptin (Kiss) on somatic growth in the cinnamon clownfish Amphiprion melanopus. We investigated the effects of Kiss treatment on the growth by measuring the mRNA expressions of the growth hormone (GH), insulin-like growth hormone factor (IGF-I), somatolactin (SL), and melatonin receptor (MT). The expression levels of GH and SL of the pituitary and IGF-I of the liver increased after Kiss treatment (in vivo and in vitro). In addition, the MT mRNA expression increased in the pituitary and brain after Kiss treatment (in vivo and in vitro). These results support the hypothesis that Kiss directly regulates the somatic growth-related factors, such as GH, SL, and MT, and IGF-I in the cinnamon clownfish. Further, injection of Kiss resulted in significantly higher levels of plasma melatonin than that in the control. We, therefore, conclude that Kiss plays a role in modulating growth and artificially induced rapid growth in cinnamon clownfish.

      PubDate: 2014-09-16T06:57:55Z
  • Effects of hypoxia on ionic regulation, glycogen utilization and
           antioxidative ability in the gills and liver of the aquatic air-breathing
           fish Trichogaster microlepis
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chun-Yen Huang , Hui-Chen Lin , Cheng-Huang Lin
      We examined the hypothesis that Trichogaster microlepis, a fish with an accessory air-breathing organ, uses a compensatory strategy involving changes in both behavior and protein levels to enhance its gas exchange ability. This compensatory strategy enables the gill ion-regulatory metabolism to maintain homeostasis during exposure to hypoxia. The present study aimed to determine whether ionic regulation, glycogen utilization and antioxidant activity differ in terms of expression under hypoxic stresses; fish were sampled after being subjected to 3 or 12 h of hypoxia and 12 h of recovery under normoxia. The air-breathing behavior of the fish increased under hypoxia. No morphological modification of the gills was observed. The expression of carbonic anhydrase II did not vary among the treatments. The Na+/K+-ATPase enzyme activity did not decrease, but increases in Na+/K+-ATPase protein expression and ionocyte levels were observed. The glycogen utilization increased under hypoxia as measured by glycogen phosphorylase protein expression and blood glucose level, whereas the glycogen content decreased. The enzyme activity of several components of the antioxidant system in the gills, including catalase, glutathione peroxidase, and superoxidase dismutase, increased in enzyme activity. Based on the above data, we concluded that T. microlepis is a hypoxia-tolerant species that does not exhibit ion-regulatory suppression but uses glycogen to maintain energy utilization in the gills under hypoxic stress. Components of the antioxidant system showed increased expression under the applied experimental treatments.

      PubDate: 2014-09-16T06:57:55Z
  • Antiviral activity of the inducible humoral immunity and its suppression
           by eleven BEN family members encoded in Cotesia plutellae bracovirus
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Ramjan Ali , Yonggyun Kim
      Upon parasitization by some endoparasitoids, polydnaviruses (PDVs) play a crucial role in inducing host immunosuppression. This study reports a novel immunosuppressive activity against humoral immune responses by BEN family genes encoded in Cotesia plutellae bracovirus (CpBV). A total of 11 BEN family members are encoded in 10 different CpBV DNA segments. When the CpBV segments were individually injected, specific BEN genes were expressed and suppressed the expression of antimicrobial peptide (AMP) and prophenoloxidase genes following bacterial challenge. The suppressive activities of the BEN genes were reversed by injection of the double-stranded RNA (dsRNA) specific to each BEN gene. The suppression of the AMP gene expressions by the BEN genes were also confirmed using an inhibition zone assay against Gram-positive and -negative bacterial growth. The significance of the suppressive activity of BEN genes against humoral immune responses was analyzed in terms of suppression of antiviral activity by the host humoral immunity. When CpBV was incubated with the plasma obtained from the larvae challenged with bacteria, the immunized plasma severely impaired the expression activity of the viral genes. However, an expression of BEN gene significantly rescued the viral gene expression by suppressing humoral immune response. These results suggest that BEN family genes of CpBV play a crucial role in defending the antiviral response of the parasitized Plutella xylostella by inhibiting humoral immune responses.

      PubDate: 2014-09-16T06:57:55Z
  • Seasonal variations in reproductive activity of the blue crab, Callinectes
           sapidus: Vitellogenin expression and levels of vitellogenin in the
           hemolymph during ovarian development
    • Abstract: Publication date: Available online 16 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Willawan Thongda , J. Sook Chung , Naoaki Tsutsui , Nilli Zmora , Anna Katenta
      In general, season affects the physiology and behavior of most animals. Warmer temperatures accelerate growth and reproduction of ectotherms, whereas these processes are slowed or halted in colder temperatures. Female blue crabs, Callinectes sapidus inhabiting the Chesapeake Bay, exhibit a seasonal migratory behavior that is closely tied with spawning and the release of larvae. To better understand reproductive activities of the migratory adult females, we examined two reproductive parameters of these crabs sampled monthly (April-December, 2006): the levels of vitellogenin (VtG) in the hemolymph and VtG expression in the hepatopancreas and ovary. The full-length cDNA of VtG (CasVtG-ova) has been isolated from the ovary. The putative CasVtG sequence found in the ovary is >99% identical to that of the hepatopancreas and is related most closely to the sequences reported in other crab species. In female C. sapidus, the hepatopancreas produces over 99% of the total VtG toward the ovarian development. Ovarian stages 2 and 3 in the sampled females are characterized by significant high levels of VtG in hemolymph and VtG expression in both the hepatopancreas and ovary. However, during the southbound migration in fall, females at ovarian stages 2 and 3 have decreased VtG levels, compared to those in spring and summer. The decreased vitellogenesis activity during the fall migration suggests seasonal adaptation to ensure successful spawning and the larval release.

      PubDate: 2014-09-16T06:57:55Z
  • High blood oxygen affinity in the air-breathing swamp eel Monopterus albus
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Christian Damsgaard , Inge Findorf , Signe Helbo , Yigit Kocagoz , Rasmus Buchanan , Do Thi Thanh Huong , Roy E. Weber , Angela Fago , Mark Bayley , Tobias Wang
      The Asian swamp eel (Monopterus albus, Zuiew 1793) is a facultative air-breathing fish with reduced gills. Previous studies have shown that gas exchange seems to occur across the epithelium of the buccopharyngeal cavity, the esophagus and the integument, resulting in substantial diffusion limitations that must be compensated by adaptations in others steps of the O2 transport system to secure adequate O2 delivery to the respiring tissues. We therefore investigated O2 binding properties of whole blood, stripped hemoglobin (Hb), two major isoHb components and the myoglobin (Mb) from M. albus. Whole blood was sampled using indwelling catheters for blood gas analysis and determination of O2 equilibrium curves. Hb was purified to assess the effects of endogenous allosteric effectors, and Mb was isolated from heart and skeletal muscle to determine its O2 binding properties. The blood of M. albus has a high O2 carrying capacity [hematocrit (Hct) of 42.4±4.5%] and binds O2 with an unusually high affinity (P 50 =2.8±0.4mmHg at 27°C and pH7.7), correlating with insensitivity of the Hb to the anionic allosteric effectors that normally decrease Hb-O2 affinity. In addition, Mb is present at high concentrations in both heart and muscle (5.16±0.99 and 1.08±0.19mg ∙ g wet tissue-1, respectively). We suggest that the high Hct and high blood O2 affinity serve to overcome the low diffusion capacity in the relatively inefficient respiratory surfaces, while high Hct and Mb concentration aid in increasing the O2 flux from the blood to the muscles.

      PubDate: 2014-09-12T05:16:16Z
  • Pigment granule translocation in red ovarian chromatophores from the
           palaemonid shrimp Macrobrachium olfersi (Weigmann, 1836): Functional roles
           for the cytoskeleton and its molecular motors
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Sarah Ribeiro Milograna , Márcia Regina Ribeiro , Munira Muhammad Abdel Baqui , John Campbell McNamara
      The binding of red pigment concentrating hormone (RPCH) to membrane receptors in crustacean chromatophores triggers Ca2+/cGMP signaling cascades that activate cytoskeletal motors, driving pigment granule translocation. We investigate the distributions of microfilaments and microtubules and their associated molecular motors, myosin and dynein, by confocal and transmission electron microscopy, evaluating a functional role for the cytoskeleton in pigment translocation using inhibitors of polymer turnover and motor activity in vitro. Microtubules occupy the chromatophore cell extensions whether the pigment granules are aggregated or dispersed. The inhibition of microtubule turnover by taxol induces pigment aggregation and inhibits re-dispersion. Phalloidin-FITC actin labeling, together with tannic acid fixation and ultrastructural analysis, reveals that microfilaments form networks associated with the pigment granules. Actin polymerization induced by jasplaquinolide strongly inhibits RPCH-induced aggregation, causes spontaneous pigment dispersion, and inhibits pigment re-dispersion. Inhibition of actin polymerization by latrunculin-A completely impedes pigment aggregation and re-dispersion. Confocal immunocytochemistry shows that non-muscle myosin II (NMMII) co-localizes mainly with pigment granules while blebbistatin inhibition of NMMII strongly reduces the RPCH response, also inducing spontaneous pigment dispersion. Myosin II and dynein also co-localize with the pigment granules. Inhibition of dynein ATPase by erythro-9-(2-hydroxy-3-nonyl) adenine induces aggregation, inhibits RPCH-triggered aggregation, and inhibits re-dispersion. Granule aggregation and dispersion depend mainly on microfilament integrity although microtubules may be involved. Both cytoskeletal polymers are functional only when subunit turnover is active. Myosin and dynein may be the molecular motors that drive pigment aggregation. These mechanisms of granule translocation in crustacean chromatophores share various features with those of vertebrate pigment cells.

      PubDate: 2014-09-12T05:16:16Z
  • Osmoregulation and branchial plasticity after acute freshwater transfer in
           red drum, Sciaenops ocellatus
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Caroline J. Watson , Wiolene M. Nordi , Andrew J. Esbaugh
      Red drum, Sciaenops ocellatus, is an estuarine-dependent fish species commonly found in the Gulf of Mexico and along the coast of the southeastern United States. This economically important species has demonstrated freshwater tolerance; however, the physiological mechanisms and costs related to freshwater exposure remain poorly understood. The current study therefore investigated the physiological response of red drum using an acute freshwater transfer protocol. Plasma osmolality, Cl−, Mg2+ and Ca2+ were all significantly reduced by 24h post-transfer; Cl− and Mg2+ recovered to control levels by 7days post-transfer. No effect of transfer was observed on muscle water content; however, muscle Cl− was significantly reduced. Interestingly, plasma and muscle Na+ content was unaffected by freshwater transfer. Intestinal fluid was absent by 24h post-transfer indicating cessation of drinking. Branchial gene expression analysis showed that both CFTR and NKCC1 exhibited significant down-regulation at 8 and 24h post-transfer, respectively, although transfer had no impact on NHE2, NHE3 or Na+, K+ ATPase (NKA) activity. These general findings are supported by immunohistochemical analysis, which revealed no apparent NKCC containing cells in the gills at 7days post transfer while NKA cells localization was unaffected. The results of the current study suggest that red drum can effectively regulate Na+ balance upon freshwater exposure using already present Na+ uptake pathways while also down-regulating ion excretion mechanisms.

      PubDate: 2014-09-12T05:16:16Z
  • The role of metabolism for understanding the altitudinal segregation
           pattern of two potentially interacting lizards
    • Abstract: Publication date: Available online 3 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Anamarija Žagar , Tatjana Simčič , Miguel A. Carretero , Al Vrezec
      Sympatric species belonging to the same ecological guild, that exhibit partial altitudinal segregation, can potentially interact when in areas of syntopic occurrence. Besides general species’ ecology, physiology can provide elusive answers about species interactions reflected in altitudinal patterns. Lizards Podarcis muralis and Iberolacerta horvathi subject to the rule of partial altitudinal segregation, while they strongly resemble in overall morphology and ecology (diet, daily and seasonal activity pattern), but show some degree of physiological dissimilarity. They have similar mean preferred body temperatures and its pattern of seasonal and daily variation but differ in the magnitude of seasonal variation. Since in ectotherms metabolism is highly dependent on body temperature, thermoregulation is expected to directly affect their metabolism. We compared metabolic rates of adult males of studied species from an area of sympatry, measured under two temperature regimes (20°C and 28°C) in search of interspecific differences in the response of metabolism to temperature change. Both species increased metabolic rates with temperature with a similar pattern. Secondly, we compared measures of electron transport activity from their tail tissues which provide values of species potential metabolic activity (enzymatic capacity). Species clearly differed in potential metabolic activity; I. horvathi attains higher values than P. muralis. No interspecific difference was detected in how species exploited this potential (calculated from the ratio of electron transport activity and metabolic rates). However, measures of electron transport activity showed higher potential metabolic activity of I. horvathi which together with the ability to thermoregulate more precisely could represent a higher competitive advantage over P. muralis in thermally more restrictive environments such as higher altitudes. Understanding of metabolism seems to provide valuable information for understanding recent distributional patterns as well as species interactions.

      PubDate: 2014-09-06T03:54:40Z
  • The actions of the renin–angiotensin system on cardiovascular and
           osmoregulatory function in embryonic chickens (Gallus gallus domesticus)
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Casey A. Mueller , Dane A. Crossley II , Warren W. Burggren
      Using embryonic chickens (Gallus gallus domesticus), we examined the role of the renin–angiotensin system (RAS) in cardiovascular and osmotic homeostasis through chronic captopril, an angiotensin-converting enzyme (ACE) inhibitor. Captopril (5mgkg−1 embryo wet mass) or saline (control) was delivered via the egg air cell daily from embryonic day 5–18. Mean arterial pressure (MAP), heart rate (ƒH), fluid osmolality and ion concentration, and embryonic and organ masses were measured on day 19. Exogenous angiotensin I (ANG I) injection did not change MAP or ƒH in captopril-treated embryos, confirming ACE inhibition. Captopril-treated embryos were significantly hypotensive, with MAP 15% lower than controls, which we attributed to the loss of vasoconstrictive ANG II action. Exogenous ANG II induced a relatively greater hypertensive response in captopril-treated embryos compared to controls. Changes in response to ANG II following pre-treatment with phentolamine (α-adrenergic antagonist) indicated a portion of the ANG II response was due to circulating catecholamines in captopril-treated embryos. An increase in MAP and ƒH in response to hexamethonium indicated vagal tone was also increased in the absence of ACE activity. Captopril-treated embryos had lower osmolality, lower Na+ and higher K+ concentration in the blood, indicating osmoregulatory changes. Larger kidney mass in captopril-treated embryos suggests disrupting the RAS may stimulate kidney growth by decreasing resistance at the efferent arteriole and increasing the fraction of cardiac output to the kidneys. This study suggests that the RAS, most likely through ANG II action, influences the development of the cardiovascular and osmoregulatory systems.

      PubDate: 2014-09-06T03:54:40Z
  • Cold hardiness and deacclimation of overwintering Papilio zelicaon pupae
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Caroline M. Williams , Annegret Nicolai , Laura V. Ferguson , Mark A. Bernards , Jessica J. Hellmann , Brent J. Sinclair
      Seasonally-acquired cold tolerance can be reversed at warm temperatures, leaving temperate ectotherms vulnerable to cold snaps. However, deacclimation, and its underlying mechanisms, has not been well-explored in insects. Swallowtail butterflies are widely distributed but in some cases their range is limited by low temperature and their cold tolerance is seasonally acquired, implying that they experience mortality resulting from deacclimation. We investigated cold tolerance and hemolymph composition of Anise swallowtail (Papilio zelicaon) pupae during overwintering in the laboratory, and after four days exposure to warm temperatures in spring. Overwintering pupae had supercooling points around −20.5°C and survived brief exposures to −30°C, suggesting partial freeze tolerance. Overwintering pupae had hemolymph osmolality of approximately 920mOsm, imparted by high concentrations of glycerol, K+ and Na+. After exposure to spring warming, supercooling points increased to approximately −17°C, and survival of a 1h exposure to −20°C decreased from 100% to 0%. This deacclimation was associated with decreased hemolymph osmolality and reduced glycerol, trehalose, Na+ and Ca2+ concentrations. We compared cold tolerance of pupae to weather conditions at and beyond the species' northern range boundary. Minimum temperatures at the range boundary approached the lower lethal temperature of pupae, and were colder north of the range, suggesting that cold hardiness may set northern range limits. Minimum temperatures following warm snaps were likely to cause mortality in at least one of the past three years. Cold snaps in the spring are increasing in frequency as a result of global climate change, so are likely to be a significant source of mortality for this species, and other temperate ectotherms.

      PubDate: 2014-09-06T03:54:40Z
  • The absence of ion-regulatory suppression in the gills of the aquatic
           air-breathing fish Trichogaster lalius during oxygen stress
    • Abstract: Publication date: Available online 3 September 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Chun-Yen Huang , Hsueh-Hsi Lin , Cheng-Huang Lin , Hui-Chen Lin
      The strategy for most teleost to survive in hypoxic or anoxic conditions is to conserve energy expenditure, which can be achieved by suppressing energy-consuming activities such as ion regulation. However, an air-breathing fish can cope with hypoxic stress using a similar adjustment, as in most teleost, or by enhancing gas exchange ability, both behaviorally and physiologically. In the present study, we examined Trichogaster lalius, an air-breathing fish without apparent gill modification, for their gill ion-regulatory abilities and glycogen utilization under a hypoxic treatment. We recorded air-breathing frequency, branchial morphology, and the expression of ion-regulatory proteins (Na+/K+-ATPase and vacuolar-type H+-ATPase) in the 1st and 4th gills and labyrinth organ (LO), and the expression of glycogen utilization (GP, glycogen phosphorylase protein expression and glycogen content) and other protein responses (catalase, CAT; carbonic anhydranse II, CAII; heat shock protein 70, HSP70; hypoxia-inducible factor-1α, HIF-1α; proliferating cell nuclear antigen, PCNA; superoxidase dismutase, SOD) in the gills of T. lalius after 3days in hypoxic and restricted conditions. In contrast to our study on other air-breathing species, no morphological modification of the 1st and 4th gills was observed. The air-breathing behavior of the fish and CAII protein expression both increased under hypoxia. Ion-regulatory abilities were not suppressed in the hypoxic or restricted groups, but glycogen utilization, indicated as GP protein expression, was enhanced within the groups. The expression of HIF-1α, HSP70 and PCNA did not vary among the treatments. Regarding the antioxidant system, decreased CAT enzyme activity was observed among the groups. In conclusion, during hypoxic stress, T. lalius did not significantly reduce energy consumption but enhanced gas exchange ability and glycogen expenditure.

      PubDate: 2014-09-06T03:54:40Z
  • Assessing stimulus and subject influences on auditory evoked potentials
           and their relation to peripheral physiology in green treefrogs (Hyla
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): Nathan P. Buerkle , Katrina M. Schrode , Mark A. Bee
      Anurans (frogs and toads) are important models for comparative studies of communication, auditory physiology, and neuroethology, but to date, most of our knowledge comes from in-depth studies of a relatively small number of model species. Using the well-studied green treefrog (Hyla cinerea), this study sought to develop and evaluate the use of auditory evoked potentials (AEPs) as a minimally invasive tool for investigating auditory sensitivity in a larger diversity of anuran species. The goals of the study were to assess the effects of frequency, signal level, sex, and body size on auditory brainstem response (ABR) amplitudes and latencies, characterize gross ABR morphology, and generate an audiogram that could be compared to several previously published audiograms for green treefrogs. Increasing signal level resulted in larger ABR amplitudes and shorter latencies, and these effects were frequency dependent. There was little evidence for an effect of sex or size on ABRs. Analyses consistently distinguished between responses to stimuli in the frequency ranges of the three previously-described populations of afferents that innervate the two auditory end organs in anurans. The overall shape of the audiogram shared prominent features with previously published audiograms. This study highlights the utility of AEPs as a valuable tool for the study of anuran auditory sensitivity.

      PubDate: 2014-09-06T03:54:40Z
  • To each its own: Thermoregulatory strategy varies among neonatal polar
    • Abstract: Publication date: Available online 21 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Linnea E. Pearson , Heather E.M. Liwanag , Mike O. Hammill , Jennifer M. Burns
      Cold environmental conditions and small body size often promote heat loss and may create thermoregulatory challenges for marine mammals born in polar regions. However, among polar-born phocid seal species there are variations in physical attributes and environmental conditions at birth, allowing for an interesting contrast in thermoregulatory strategy. We compared aspects of thermoregulatory strategies including morphometrics, sculp attributes (conductivity and resistance), nonshivering thermogenesis (NST via uncoupling protein 1; UCP1), and muscle thermogenesis (via enzyme activity) in neonatal harp (Pagophilus groenlandicus), hooded (Cystophora cristata), and Weddell seals (Leptonychotes weddellii). Harp seals are the smallest at birth (9.8±0.7kg), rely on lanugo (82.49±3.70% of thermal resistance), and are capable of NST through expression of UCP1 in brown adipose tissue (BAT). In contrast, hooded seal neonates (26.8±1.3kg) have 2.06±0.23cm of blubber, accounting for 38.19±6.07% of their thermal resistance. They are not capable of NST, as UCP1 is not expressed. The large Weddell seal neonates (31.5±4.9kg) rely on lanugo (89.85±1.25% of thermal resistance) like harp seals, but no evidence of BAT was found. Muscle enzyme activity was highest in Weddell seal neonates, suggesting they rely primarily on muscle thermogenesis. Similar total thermal resistance, combined with the marked differences in thermogenic capacity of NST and ST among species, strongly supports the idea that thermoregulatory strategy in neonate phocids is more closely tied to pups' surface area to volume ratio (SA:V) and potential for early water immersion rather than mass and ambient environmental conditions.

      PubDate: 2014-09-02T02:29:30Z
  • Testing the heat-invariant and cold-variability tolerance hypotheses
           across geographic gradients
    • Abstract: Publication date: Available online 23 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Francisco Bozinovic , María J.M. Orellana , Sebastián I. Martel , José M. Bogdanovich
      Changes in temperature across geographic gradients can occur on a wide temporal range, from fluctuations within hours as a result of day-night to those over many years. These events will drive many organisms towards their physiological limits of thermal tolerance. Recently, many reports support a limited scope for adaptive evolutionary responses to high temperatures, meaning a conserved heat tolerance among ectotherms in general. We address this problem and tested the heat and cold tolerance invariant–variant hypotheses in terrestrial isopods. We studied five different populations of Porcellio laevis and three populations of Porcellio scaber, spanning 30° S latitudinal gradient in Chile. The heat tolerance of woodlice was conserved with little variation along latitude and environmental temperatures, but cold tolerance decreases significantly with environmental temperatures and latitudes. Indeed, a significant and negative correlation was observed between cold tolerance and latitude. Also, significant and positive correlations were observed among cold tolerance and environmental temperatures. Conversely, heat tolerance was not significantly correlated with any of the environmental temperatures tested neither with latitude. This macrophysiological pattern indicated that heat and cold-tolerances of species and populations not always change across geographical gradients meaning that thermal tolerance responses to high temperatures may be evolutionary constrained.

      PubDate: 2014-09-02T02:29:30Z
  • Editorial Board
    • Abstract: Publication date: November 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 177

      PubDate: 2014-09-02T02:29:30Z
  • Hearts of some Antarctic fishes lack mitochondrial creatine kinase
    • Abstract: Publication date: December 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 178
      Author(s): K.M. O'Brien , I.A. Mueller , J.I. Orczewska , K.R. Dullen , M. Ortego
      Creatine kinase (CK; EC functions as a spatial and temporal energy buffer, dampening fluctuations in ATP levels as ATP supply and demand change. There are four CK isoforms in mammals, two cytosolic isoforms (muscle [M-CK] and brain [B-CK]), and two mitochondrial isoforms (ubiquitous [uMtCK] and sarcomeric [sMtCK]). Mammalian oxidative muscle couples expression of sMtCK with M-CK, creating an energy shuttle between mitochondria and myofibrils. We hypothesized that the expression pattern and activity of CK would differ between hearts of red- and white-blooded Antarctic notothenioid fishes due to their striking differences in cardiac ultrastructure. Hearts of white-blooded icefishes (family Channichthyidae) have significantly higher mitochondrial densities compared to red-blooded species, decreasing the diffusion distance for ATP between mitochondria and myofibrils and potentially minimizing the need for CK. The distribution of CK isoforms was evaluated using western blotting and maximal activity of CK was measured in mitochondrial and cytosolic fractions and tissue homogenates of heart ventricles of red- and white-blooded notothenioids. Transcript abundance of sMtCK and M-CK was also quantified. Overall, CK activity is similar between hearts of red- and white-blooded notothenioids but hearts of icefishes lack MtCK and have higher activities of M-CK in the cytosol compared to red-blooded fishes. The absence of MtCK may compromise cardiac function under stressful conditions when ATP supply becomes limiting.

      PubDate: 2014-09-02T02:29:30Z
  • The peptide hormone cholecystokinin modulates the tonus and compliance of
           the bulbus arteriosus and pre-branchial vessels of the rainbow trout
           (Oncorhynchus mykiss)
    • Abstract: Publication date: Available online 4 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Henrik Seth , Michael Axelsson , Albin Gräns
      The bulbus arteriosus is a compliant structure between the ventricle and ventral aorta of teleost fish. It serves as a “wind-kessel” that dampens pressure variations during the cardiac cycle allowing a continuous flow of blood into the gills. The bulbus arteriosus receives sympathetic innervation and is affected by several circulating substances, indicating neurohumoral control. We have previously shown that the peptide hormone, cholecystokinin (CCK), affects the hemodynamics of the cardiovascular system in rainbow trout (Oncorhynchus mykiss) by increasing flow pulse amplitude without affecting cardiac output. We hypothesized that this could be explained by an altered tonus or compliance/distensibility of the bulbus arteriosus. Our results show that there is a substantial effect of CCK on the bulbus arteriosus. Concentrations of CCK that altered the cardiac function of in situ perfused hearts also contracted the bulbus arteriosus in vitro. Pressure–volume curves revealed a change in both the tonus and the compliance/distensibility of this structure. Furthermore, the stimulatory (constricting) effect of CCK was also evident in the ventricle and vasculature leading to the gills, but absent in the atrium, efferent branchial arteries and dorsal aorta. In conclusion, CCK alters the mechanical properties of the ventricle, bulbus arteriosus, ventral aorta and afferent gill vasculature, thus maintaining adequate branchial and systemic blood flow and pressure when cardiorespiratory demands change, such as after feeding.

      PubDate: 2014-08-08T00:31:18Z
  • How do measurement duration and timing interact to influence estimation of
           basal physiological variables of a nocturnal rodent?
    • Abstract: Publication date: Available online 7 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): M.K. Connolly , C.E. Cooper
      Metabolic rate and evaporative water loss are two commonly measured physiological variables. It is therefore important, especially for comparative studies, that these variables (and others) are measured under standardised conditions, of which a resting state during the inactive phase is part of the accepted criteria. Here we show how measurement duration and timing affect these criteria and impact on the estimation of basal metabolic rate (oxygen consumption and carbon dioxide production) and standard evaporative water loss of a small nocturnal rodent. Oxygen consumption, carbon dioxide production and evaporative water loss all decreased over the duration of an experiment. Random assortment of hourly values indicated that this was an animal rather than a random effect for up to 11h. Experimental start time also had a significant effect on measurement of physiological variables. A longer time period was required to achieve minimal carbon dioxide consumption and evaporative water loss when experiments commenced earlier in the day, however experiments with earlier start times had a lower overall estimates of minimal oxygen consumption and carbon dioxide production. For this species, measurement duration of at least 8h, ideally commencing between before the inactive phase at 03:00h and 05:00h, is required to obtain minimal standard values for physiological variables. Up to 80% of recently published studies measuring basal metabolic rate and/or evaporative water loss of small nocturnal mammals may overestimate basal values due to insufficiently long measurement duration.

      PubDate: 2014-08-08T00:31:18Z
  • Editorial Board
    • Abstract: Publication date: October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 176

      PubDate: 2014-08-04T00:01:24Z
  • Immune responsiveness of Japanese quail selected for egg yolk testosterone
           content under severe protein restriction
    • Abstract: Publication date: Available online 30 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Zuzana Kankova , Monika Okuliarova , Michal Zeman
      Yolk testosterone concentrations vary in response to environmental conditions and different testosterone contents can subsequently modify the phenotypic traits of offspring. Apart from effects on growth, proactive behaviour and secondary sexual characteristics, the possible negative impacts of maternal testosterone on the immune system are often considered a limitation for its deposition. The effects of maternal testosterone can be modulated by postnatal environmental conditions, such as the availability of food resources. However, the majority of studies considering the effects of maternal testosterone on the immune system have been conducted under optimum conditions. In our study we evaluated the influence of genetic selection for high (HET) and low (LET) egg testosterone content in Japanese quail on immune responsiveness of offspring to phytohaemagglutinin (PHA) and lipopolysaccharide (LPS) stimulation under severe protein restriction. Protein restriction negatively influenced body weight and performance in the PHA-test. We observed an increase in Cort (corticosterone) and He/Ly (heterophil/lymphocyte ratio) after LPS, whilst no changes occurred in total IgY levels in the protein-restricted group. HET quails showed higher body mass and total IgY levels and lower He/Ly ratio than LET quails, whilst the PHA index and Cort concentration did not differ between lines. No interactions were found between protein restriction and genetic line. In conclusion, the immune response was not compromised under conditions of severe protein restriction in the faster growing HET line compared with the LET line. We hypothesise that the immune responsiveness of birds with higher yolk testosterone may be linked with other maternally-derived substances in a context-dependent manner.

      PubDate: 2014-08-04T00:01:24Z
  • A critical evaluation of automated blood gas measurements in comparative
           respiratory physiology
    • Abstract: Publication date: Available online 1 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Christian Lind Malte , Sashia Lindhøj Jakobsen , Tobias Wang
      Precise measurements of blood gases and pH are of pivotal importance to respiratory physiology. However, the traditional electrodes that could be calibrated and maintained at the same temperature as the experimental animal are increasingly being replaced by new automated blood gas analyzers. These are typically designed for clinical use and automatically heat the blood sample to 37°C for measurements. While most blood gas analyzers allow for temperature corrections of the measurements, the underlying algorithms are based on temperature-effects for human blood, and any discrepancies in the temperature dependency between the blood sample from a given species and human samples will bias measurements. In this study we review the effects of temperature on blood gases and pH and evaluate the performance of an automated blood gas analyzer (GEM Premier 3500). Whole blood obtained from pythons and freshwater turtles was equilibrated in rotating Eschweiler tonometers to a variety of known PO2's and PCO2's in gas mixtures prepared by Wösthoff gas mixing pumps and blood samples were measured immediately on the GEM Premier 3500. The pH measurements were compared to measurements using a Radiometer BMS glass capillary pH electrode kept and calibrated at the experimental temperature. We show that while the blood gas analyzer provides reliable temperature-corrections for PCO2 and pH, PO2 measurements were substantially biased. This was in agreement with the theoretical considerations and emphasizes the need for critical calibrations/corrections when using automated blood gas analyzers.

      PubDate: 2014-08-04T00:01:24Z
  • Different stressors induce differential responses of the CRH-stress system
           in the gilthead sea bream (Sparus aurata)
    • Abstract: Publication date: Available online 1 August 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Juan A. Martos-Sitcha , Yvette S. Wunderink , Justin Straatjes , Arleta K. Skrzynska , Juan M. Mancera , Gonzalo Martínez-Rodríguez
      The hypothalamus–pituitary–interrenal (HPI) axis, involved in the regulation of the neuroendocrine stress responses, presents important players such as corticotropin-releasing hormone (CRH, generally considered as the initiator of this pathway) and CRH-binding protein (CRH-BP, considered as an antagonist of CRH function). CRH and CRH-BP full-length cDNA sequences were obtained from Sparus aurata by screening a brain cDNA library, and their phylogenetic analysis as well as their roles during acute and chronic stress responses were assessed. mRNA expression levels and plasma cortisol concentrations were measured by RT qPCR and ELISA, respectively, in S. aurata juveniles submitted to: i) different environmental salinities in a short-time course response; and ii) food deprivation during 21days. In addition, osmoregulatory and metabolic parameters in plasma corroborated a clear reorganization depending on the stress source/period. Salinity transfer induced stress as indicated by enhanced plasma cortisol levels, as well as by up-regulated CRH and down-regulated CRH-BP expression values. On the other hand, food deprivation did not affect both expression levels, although plasma cortisol concentrations were enhanced. These results suggest that different stressors are handled through different stress pathways in S. aurata.

      PubDate: 2014-08-04T00:01:24Z
  • Changes in plasma concentrations of progesterone, dehydroepiandrosterone
           and corticosterone in response to acute stress of capture, handling and
           restraint in two subspecies of white-crowned sparrows
    • Abstract: Publication date: Available online 27 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Jesse S. Krause , David Dorsa , John C. Wingfield
      The aim of this study was to determine circulating patterns of the three major adrenal steroids in blood in response to stress during acute restraint handling in two subspecies of white-crowned sparrow (Zonotrichia leucophrys). Gambel’s white-crowned sparrows (Z.l. gambelii) are long distance migrants that breed at high latitudes and Nuttall’s white-crowned sparrows (Z.l. nuttalli) are residents of coastal California. Column partition chromatography was developed to separate progesterone, dehydroepiandrosterone (DHEA), and corticosterone from a small plasma sample. Each of these steroids has the capability to modulate the stress response through various mechanisms. For example, progesterone is bound to corticosterone binding globulin (CBG) with a higher affinity than corticosterone. If plasma levels of progesterone rise during acute stress, then this could displace corticosterone from CBG and increase the amount of biologically active, free, corticosterone in blood. Dehydroepiandrosterone (DHEA) has been implicated to have many anti-stress properties with the potential to mitigate some of the actions of corticosterone. Results indicate that progesterone levels in both subspecies are elevated in response to acute stress handling. DHEA levels declined in Gambel’s but did not change in Nuttall’s. Thus DHEA does not follow the same secretory pattern as in mammals. Corticosterone levels were elevated in response to acute stress handling in both subspecies. This study provides new insight into an integrated stress response among three steroids.

      PubDate: 2014-07-29T23:41:14Z
  • Sex-specific divergence for body size and desiccation-related traits in
           Drosophila hydei from the western Himalayas
    • Abstract: Publication date: Available online 18 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Bhawna Kalra , Ravi Parkash
      Sex-specific-differences are a widespread source of genetic variation in various Drosophila species. In the present study, we have examined desiccation survival in males and females of Drosophila hydei from colder and drier montane conditions of the western Himalayas (altitudinal populations; 600–2202m). In contrast with most other studies in drosophilids, D. hydei males exhibited comparatively higher desiccation resistance despite smaller body size compared to females. Accordingly, we tested the physiological basis of such adaptations in both sexes of D. hydei. Body size traits (wing length, wet weight and dry weight) were ~1.2 fold higher in females than males. However, desiccation resistance was 10 to 13h higher in males than females. These differences matched enhanced storage of trehalose content (~1.2 fold), higher hemolymph content (~1.2 fold) and enhanced cuticular lipid mass (~1.5 fold) in males than females. Water loss before succumbing to death (dehydration tolerance) was much higher in males (~81%) than females (~64%). A greater loss of hemolymph water until death under desiccation stress was associated with higher desiccation resistance in males. Further, there were lacks of differences in the rate of water loss, rate of trehalose utilization and rate of hemolymph depletion between the sexes in D. hydei. Therefore, sex-specific differences in desiccation resistance of D. hydei were independent of body size as well as the exhaustion of metabolite reserves and rather were caused by the higher dehydration tolerance as well as higher acquisition of hemolymph and trehalose contents.

      PubDate: 2014-07-26T23:36:34Z
  • Lipid metabolites as markers of fattening rate in a non-migratory
           passerine: Effects of ambient temperature and individual variation
    • Abstract: Publication date: Available online 24 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Isabelle Devost , Fanny Hallot , Myriam Milbergue , Magali Petit , François Vézina
      Plasma lipid metabolites such as triglycerides (TRIG) and glycerol (GLY) are used as indicators of fattening rate and nutritional condition in migratory birds. Requiring only one blood sample, they could also be used for studying daily and seasonal fattening rates in relation with habitat quality or weather variations in small species wintering in cold climates. Using captive black-capped chickadees (Poecile atricapillus) exposed to three experimental temperatures (0°C, 15°C, and 30°C), the goal of this experiment was to determine the relationship between plasma levels of both TRIG and GLY and fattening rate measured over periods varying from a few hours to the previous two days. Results showed that birds maintained in the cold had circulating metabolite levels 39–81% higher than those maintained at thermoneutrality, likely reflecting the size of their body fat reserves and that TRIG and total GLY were highly correlated across treatments. Fattening rate was also higher both at 0°C (+35%) and 30°C (+24%) relative to that measured at 15°C and, as expected, was positively correlated with metabolite levels across thermal treatments. However, despite a range of fattening rates similar to that observed at the other temperatures, the relationships were uncoupled at 30°C, implying that the technique may not be easily applicable at temperatures within or close to thermoneutrality. We also found a strong individual effect in the relationships between fattening rate and plasma TRIG levels, suggesting high individual consistency in these parameters in conditions of unrestricted food access such as in captivity. Our study therefore confirms that plasma TRIG and GLY levels can be used as relative indexes of condition and fattening rates in wintering passerines.

      PubDate: 2014-07-26T23:36:34Z
  • Non-invasive assessment of adrenocortical function in captive Nile
           crocodiles (Crocodylus niloticus)
    • Abstract: Publication date: Available online 24 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Stefanie B. Ganswindt , Jan G. Myburgha , Elissa Z. Cameron , Andre Ganswindt
      The occurrence of stress-inducing factors in captive crocodilians is a concern, since chronic stress can negatively affect animal health and reproduction, and hence production. Monitoring stress in wild crocodiles could also be beneficial for assessing the state of health in populations which are potentially threatened by environmental pollution. In both cases, a non-invasive approach to assess adrenocortical function as a measure of stress would be preferable, as animals are not disturbed during sample collection, and therefore sampling is feedback-free due to the absence of capture and handling. So far, however, such a non-invasive method has not been established for any crocodilian species. As an initial step, we therefore examined the suitability of two enzyme-immunoassays, detecting faecal glucocorticoid metabolites (FGMs) with a 11β,21-diol-20-one and 5β-3α-ol-11-one structure, respectively, for monitoring stress-related physiological responses in captive Nile crocodiles (Crocodylus niloticus). An adrenocorticotropic hormone (ACTH) challenge was performed on 10 sub-adult crocodiles, resulting in an overall increase in serum corticosterone levels of 272% above the pre-injection levels 5h post-injection. Saline-treated control animals (n=8) showed an overall increase of 156% in serum corticosterone levels 5h post-administration. Faecal samples pre- and post-injection could be obtained from three of the six individually housed crocodiles, resulting in FGM concentrations 136-380% above pre-injection levels, always detected in the first sample collected post-treatment (7–15 days post-injection). FGM concentrations seem comparatively stable at ambient temperatures for up to 72h post-defaecation. In conclusion, non-invasive hormone monitoring can be used for assessing adrenocortical function in captive Nile crocodiles based on FGM analysis.

      PubDate: 2014-07-26T23:36:34Z
  • Point mutagenesis reveals that a coiled-coil motif of CrV1 is required for
           entry to hemocytes to suppress cellular immune responses
    • Abstract: Publication date: Available online 26 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Sunil Kumar , Yonggyun Kim
      Various immunosuppressive factors are derived from polydnaviruses (PDVs) mutually symbiotic to some ichneumonid and braconid wasps. CrV1 was originally identified from a PDV called Cotesia rubecula bracovirus. CrV1 orthologs are reported in other Cotesia-associated PDVs, but not clearly understood in their physiological functions. This study determined a function of CrV1 encoded in C. plutellae bracovirus (CpBV). CpBV-CrV1 is the largest molecule among the known CrV1s and is predicted to possess three coiled-coil motifs. It was constitutively expressed in parasitized host, Plutella xylostella. In vivo transient expression of CpBV-CrV1 significantly impaired hemocyte nodule formation. However, its specific RNA interference significantly recovered the immune response. Two point mutations (Ala→Pro at 192nd and 196th positions) were designed to remove the main coiled-coil motif of CpBV-CrV1. When CpBV-CrV1 and the mutant CpBV-CrV1 were expressed in Sf9 cells, their proteins were synthesized and secreted into each culture medium. When each culture medium was overlaid on hemocytes of nonparasitized P. xylostella, an immunofluorescence assay showed that CpBV-CrV1 entered the hemocytes, but the mutant protein did not. The entered CpBV-CrV1 significantly inhibited hemocyte-spreading behavior by preventing F-actin formation. These results indicate that CpBV-CrV1 is an immunosuppressive factor of CpBV, in which its coiled-coil motif is essential.

      PubDate: 2014-07-26T23:36:34Z
  • Exploring the consequences of mitochondrial differences arising through
           hybridization of sunfish
    • Abstract: Publication date: Available online 26 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): K. Mathers , J. Cox , Y. Wang , C.D. Moyes
      Previous studies have shown evidence of genomic incompatibility and mitochondrial enzyme dysfunction in hybrids of bluegill (Lepomis macrochirus Rafinesque) and pumpkinseed (L. gibbosus Linnaeus) sunfish (Davies et al., 2013 Physiol. Biochem. Zool. 85, 321–331). We assessed if these differences in mitochondria had an impact on metabolic processes that depend on mitochondrial function, specifically hypoxia tolerance and recovery from burst exercise. Bluegill, pumpkinseed, and their hybrids showed no difference in the critical oxygen tension (Pcrit) and no differences in tissue metabolites measured after exposure to 10% O2 for 30min. In contrast, loss of equilibrium (LOE) measurements showed that hybrids had reduced hypoxia tolerance and lacked the size-dependence in hypoxia tolerance seen in the parental species. However, we found no evidence of systematic differences in metabolite levels in fish after LOE. Furthermore, there were abundant glycogen reserves at the point of loss of equilibrium. The three genotypes did not differ in metabolite status at rest, showed an equal disruption at exhaustion, and similar metabolic profiles throughout recovery. Thus, we found no evidence of a mitochondria dysfunction in hybrids, and mitochondrial differences and oxidative metabolism did not explain the variation in hypoxia tolerance seen in the hybrid and two parental species.

      PubDate: 2014-07-26T23:36:34Z
  • Corrigendum to “Variability in swimming performance and underlying
           physiology in rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo
           trutta)” [Comp. Biochem. Physiol., A 163 (2012) 350–356]
    • Abstract: Publication date: October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 176
      Author(s): Allison L. Ralph , Barbara I. Berli , Patricia Burkhardt-Holm , Keith B. Tierney

      PubDate: 2014-07-26T23:36:34Z
  • The effects of poly-unsaturated fatty acids on the physiology of
           hibernation in a South American marsupial, Dromiciops gliroides
    • Abstract: Publication date: Available online 15 July 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Carolina Contreras , Marcela Franco , Ned J. Place , Roberto F. Nespolo
      Many mammals hibernate, which is a profound lethargic state of several weeks or months during winter, is a case that represents a transitory episode of hetherothermy. As with other cases of dormancy, the main benefit of hibernation seems to be energy saving. However, the depth and duration of torpor can be experimentally modified by the composition of food, especially by fattyacid composition. In eutherians, diets rich in unsaturated fatty acids (i.e., fatty acids with at least one double bond) lengthen torpor, reduce metabolism and permit hibernation at lower temperatures. Here we studied whether diets varying in fatty acid composition have an effect on the physiology of hibernation in a South American marsupial, Dromiciops gliroides. We designed a factorial experiment where thermal acclimation (two levels: natural versus constant temperature) was combined with diet acclimation: saturated (i.e., diets with high concentration of saturated fatty acids) versus unsaturated (i.e., diets with high concentration of unsaturated fatty acids). We measured energy metabolism in active and torpid individuals, as well as torpor duration, and a suite of 12 blood biochemical parameters. After a cafeteria test, we found that D. gliroides did not show any preference for a given diet. Also, we did not find effects of diet on body temperature during torpor, or its duration. However, saturated diets, combined with high temperatures provoked a disproportionate increase in fat utilization, leading to body mass reduction. Those animals were more active, and metabolized more fats than those fed with a high proportion of unsaturated fatty acids (=“unsaturated diets”). These results contrast with previous studies, which showed a significant effect of fatty acid composition of diets on food preferences and torpor patterns in mammals.

      PubDate: 2014-07-26T23:36:34Z
  • Changes in calpains and calpastatin in the soleus muscle of Daurian ground
           squirrels during hibernation
    • Abstract: Publication date: October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 176
      Author(s): Chen-Xi Yang , Yue He , Yun-Fang Gao , Hui-Ping Wang , Nandu Goswami
      We investigated changes in muscle mass, calpains, calpastatin and Z-disk ultrastructure in the soleus muscle (SOL) of Daurian ground squirrels (Spermophilus dauricus) after hibernation or hindlimb suspension to determine possible mechanisms by which muscle atrophy is prevented in hibernators. Squirrels (n=30) were divided into five groups: no hibernation group (PRE, n=6); hindlimb suspension group (HLS, n=6); two month hibernation group (HIB, n=6); twoday group after 90±12days of hibernation (POST, n=6); and forced exercise group (one time forced, moderate-intensity treadmill exercise) after arousal (FE, n=6). Activity and protein expression of calpains were determined by casein zymography and western blotting, and Z-disk ultrastructure was observed by transmission electron microscopy. The following results were found. Lower body mass and higher SOL muscle mass (mg) to total body mass (g) ratio were observed in HIB and POST; calpain-1 activity increased significantly by 176% (P =0.034) in HLS compared to the PRE group; no significant changes were observed in calpain-2 activity. Protein expression of calpain-1 and calpain-2 increased by 83% (P =0.041) and 208% (P =0.029) in HLS compared to the PRE group, respectively; calpastatin expression increased significantly by 180% (P <0.001) and 153% (P =0.007) in HIB and POST, respectively; the myofilaments were well-organized, and the width of the sarcomere and the Z-disk both appeared visually similar among the pre-hibernation, hibernating and post-hibernation animals. Inhibition of calpain activity and consequently calpain-mediated protein degradation by highly elevated calpastatin protein expression levels may be an important mechanism for preventing muscle protein loss during hibernation and ensuring that Z-lines remained ultrastructurally intact.

      PubDate: 2014-07-26T23:36:34Z
  • Enthalpic partitioning of the reduced temperature sensitivity of O2
           binding in bovine hemoglobin
    • Abstract: Publication date: October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 176
      Author(s): Roy E. Weber , Angela Fago , Kevin L. Campbell
      The oxygenation enthalpy of the heme groups of hemoglobin (Hb) is inherently exothermic, resulting in decreased Hb-O2 affinity with rising temperature. However, oxygenation is coupled with endothermic dissociation of allosteric effectors (e.g. protons, chloride ions and organic phosphates) from the protein, which reduces the overall oxygenation enthalpy. The evolution of Hbs with reduced temperature sensitivity ostensibly safeguards O2 unloading in cold extremities of regionally-heterothermic vertebrates permitting energy-saving reductions in heat loss. Ungulate (e.g. bovine) Hbs have long served as a model system in this regard in that they exhibit numerically low oxygenation enthalpies that are thought to correlate with the presence of an additional Cl− binding site (compared to human Hb) comprised of three cationic residues at positions 8, 76 and 77 of the β-chains of Hb. However, ungulate Hbs also exhibit distinctive amino acid exchanges at the N-termini of the β-chains that stabilize the low-affinity deoxystructure of the Hb, mimicking the action of organic phosphates. In order to assess the relative contributions from these two effects, we measured the temperature sensitivity of Hb-O2 affinity in bovine and human Hbs in the absence and presence of Cl− ions under strictly controlled pH conditions. The data indicate that Cl−-binding accounts for a minority (~30%) of the total reduction in the oxygenation enthalpy manifested in bovine compared to human Hb, whereas the majority of this reduction is ascribable to structural differences, including increased β-chain hydrophobicity that would increase the heat of oxygenation-linked conformational change in bovine Hb.

      PubDate: 2014-07-26T23:36:34Z
  • Chicken hatchlings prefer ambient temperatures lower than their
           thermoneutral zone
    • Abstract: Publication date: October 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Volume 176
      Author(s): Paula Andrea Toro-Velasquez , Kênia C. Bícego , Jacopo P. Mortola
      We investigated whether or not the preferred ambient temperature (Tapref) of the 1-day old chicken hatchling, a precocial neonate with excellent locomotory capacity, clearly identifiable thermogenesis and independence from maternal care, coincides with the lower critical temperature (LCT) of thermoneutrality and minimal oxygen consumption ( V ˙ O 2 ). Tapref of single chicks measured in a thermocline (N =16) averaged 33.5±0.3°C (mode, 33.3±0.4°C). The same value was obtained in hatchlings studied in pairs. LCT was computed from the ambient temperature (Ta)– V ˙ O 2 relationship, constructed by slowly decreasing the Ta of a respirometer from 38 to 29°C over 2.5h, while continuously measuring V ˙ O 2 by an open-flow methodology; LCT averaged 36.4°C±0.3 or 36.8°C±0.4, depending on the method of computation. In all hatchlings Tapref was lower than LCT (P <0.001), by a magnitude that depended on the method of computation of the two variables, 2.8°C±0.3 (P <0.001) or 3.9°C±0.5. The Tapref-LCT difference implied that, at Tapref, V ˙ O 2 was higher than at thermoneutrality. We conclude that in the chicken hatchling thermal preference does not coincide with thermoneutrality, probably because during development what seems optimal from a thermoregulatory viewpoint may not necessarily be so for other regulatory functions.

      PubDate: 2014-07-26T23:36:34Z
  • Acute exposure to a common suspended sediment affects the swimming
           performance and physiology of juvenile salmonids
    • Abstract: Publication date: Available online 6 June 2014
      Source:Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
      Author(s): Barbara I. Berli , Matthew J.H. Gilbert , Allison L. Ralph , Keith B. Tierney , Patricia Burkhardt-Holm
      To study the effects of an acute exposure to turbidity generated by suspended sediment, we examined swimming performance (U crit) and related metabolic parameters in individual and groups of juvenile trout at three different concentrations of calcium carbonate. To investigate differences among strains or provenience, we compared one strain of rainbow trout (Oncorhynchus mykiss; RBT) and one strain of brown trout (Salmo trutta; BNT) from a common hatchery and one RBT strain from a separate hatchery. In general, trout swum individually or in groups exhibited a decrease in U crit as turbidity increased. Both RBT strains were more similar to each other and were impaired to a larger extent in swimming performance than BNT, which was less impacted. For groups, indicators of aerobic metabolism were elevated while those of anaerobic metabolism were depressed. Specifically, citrate synthase activities and glucose levels tended to be greater while plasma lactate and LDH activities were reduced. Lactate and LDH levels in individually swum trout under sediment exposure suggest a greater similarity of fish from the same provenience. We suggest that acute exposures to environmentally relevant turbidities generated by fine suspended sediment may cause a reduced U crit, and that these changes may be related to changes in the utilization of aerobic and anaerobic pathways.

      PubDate: 2014-06-07T16:03:50Z
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