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Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology

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https://www.readbyqxmd.com/read/28332020/temperature-effects-on-the-activity-shape-and-storage-of-platelets-from-13-lined-ground-squirrels
#1
Scott Cooper, Sarah Lloyd, Anthony Koch, Xingxing Lin, Katie Dobbs, Thomas Theisen, Matt Zuberbuehler, Kaley Bernhardt, Michael Gyorfi, Tanner Tenpas, Skyler Hying, Sarah Mortimer, Christine Lamont, Marcus Lehmann, Keith Neeves
The objective of this study is to determine how a hibernating mammal avoids the formation of blood clots under periods of low blood flow. A microfluidic vascular injury model was performed to differentiate the effects of temperature and shear rate on platelet adhesion to collagen. Human and ground squirrel whole blood was incubated at 15 or 37 °C and then passed through a microfluidic chamber over a 250-µm strip of type I fibrillar collagen at that temperature and the shear rates of 50 or 300 s(-1) to simulate torpid and aroused conditions, respectively...
March 23, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28332019/comparative-tissue-transcriptomics-highlights-dynamic-differences-among-tissues-but-conserved-metabolic-transcript-prioritization-in-preparation-for-arousal-from-torpor
#2
Lori K Bogren, Katharine R Grabek, Gregory S Barsh, Sandra L Martin
During the hibernation season, 13-lined ground squirrels spend days to weeks in torpor with body temperatures near freezing then spontaneously rewarm. The molecular drivers of the drastic physiological changes that orchestrate and permit torpor are not well understood. Although transcription effectively ceases at the low body temperatures of torpor, previous work has demonstrated that some transcripts are protected from bulk degradation in brown adipose tissue (BAT), consistent with the importance of their protein products for metabolic heat generation during arousal from torpor...
March 23, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28332018/seasonal-loss-and-resumption-of-circadian-rhythms-in-hibernating-arctic-ground-squirrels
#3
Cory T Williams, Maya Radonich, Brian M Barnes, C Loren Buck
Circadian clocks are near universal among organisms and play a key role in coordinating physiological and metabolic functions to anticipate or coincide with predictable daily changes in the physical and social environment. However, whether circadian rhythms persist and are functionally important during hibernation in all mammals is currently unclear. We examined whether circadian rhythms of body temperature (T b) persist during multi-day, steady-state torpor and investigated the association between timing of animal emergence, exposure to light, and resumption of activity and T b rhythms in free-living and captive male arctic ground squirrels...
March 22, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324161/thermal-ecology-of-three-coexistent-desert-lizards-implications-for-habitat-divergence-and-thermal-vulnerability
#4
Shu-Ran Li, Yang Wang, Liang Ma, Zhi-Gao Zeng, Jun-Huai Bi, Wei-Guo Du
How ectotherms exploit thermal resources has important implications for their habitat utilization and thermal vulnerability to climate warming. To address this issue, we investigated thermal relations of three sympatric lizard species (Eremias argus, Eremias multiocellata, and Phrynocephalus przewalskii) in the desert steppe of Inner Mongolia, China. We determined the thermoregulatory behavior, body temperature (T b), operative temperature (T e), selected body temperature (T sel), and critical thermal maximum (CTmax) of adult lizards...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324160/regulation-of-blood-oxygen-transport-in-hibernating-mammals
#5
Inge G Revsbech, Angela Fago
Along with the periodic reductions in O2 requirements of mammalian hibernators during winter, the O2 affinity of the blood of mammalian hibernators is seasonally regulated to help match O2 supply to consumption, contributing to limit tissue oxidative stress, particularly at arousals. Specifically, mammalian hibernators consistently show an overall increase in the blood-O2 affinity, which causes a decreased O2 unloading to tissues, while having similar or lower tissue O2 tensions during hibernation. This overview explores how the decreased body temperature and concentration of red blood cell 2,3-diphosphoglycerate (DPG) that occur in hibernation contribute separately or in combination to the concurrent increase in the O2 affinity of the hemoglobin, the O2 carrier protein of the blood...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324159/hibernation-based-blood-loss-therapy-increases-survivability-of-lethal-hemorrhagic-shock-in-rats
#6
Cecilia E Perez de Lara Rodriguez, Lester R Drewes, Matthew T Andrews
A small-volume (1 ml/kg) resuscitation fluid based on metabolic adaptations in hibernating mammals was optimized using a rat model of hemorrhagic shock. A previous study of this therapy tested only one concentration of three specific components: 4 M D-stereoisomer of beta-hydroxybutyrate (BHB), 43 mM melatonin, and 20% DMSO. In this study, we considered the range of concentrations of BHB and melatonin seen during the physiological extremes of rapid arousal from hypothermic torpor in natural hibernators and applied these to the non-hibernating Sprague-Dawley rat model...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324158/the-influence-of-sex-and-diet-on-the-characteristics-of-hibernation-in-syrian-hamsters
#7
Marie Trefna, Maaike Goris, Cynthia M C Thissen, Vera A Reitsema, Jojanneke J Bruintjes, Edwin L de Vrij, Hjalmar R Bouma, Ate S Boerema, Robert H Henning
Research on deep hibernators almost exclusively uses species captured from the wild or from local breeding. An exception is Syrian hamster (Mesocricetus auratus), the only standard laboratory animal showing deep hibernation. In deep hibernators, several factors influence hibernation quality, including body mass, sex and diet. We examined hibernation quality in commercially obtained Syrian hamsters in relation to body mass, sex and a diet enriched in polyunsaturated fatty acids. Animals (M/F:30/30, 12 weeks of age) were obtained from Harlan (IN, USA) and individually housed at 21 °C and L:D 14:10 until 20 weeks of age, followed by L:D 8:16 until 27 weeks...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324157/water-fat-mri-in-a-hibernator-reveals-seasonal-growth-of-white-and-brown-adipose-tissue-without-cold-exposure
#8
Amanda MacCannell, Kevin Sinclair, Lannette Friesen-Waldner, Charles A McKenzie, James F Staples
Obligate hibernators, such as ground squirrels, display circannual patterns which persist even under constant laboratory conditions, suggesting that they are regulated by endogenous rhythms. Brown adipose tissue (BAT) is important for thermogenesis during periodic arousals from hibernation when core body temperature rises spontaneously from 5 to 37 °C. In most small eutherians BAT growth requires several weeks of cold exposure. We hypothesized that in the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), a hibernator, BAT growth is regulated, in part, by an endogenous rhythm and we predicted that this growth would precede the hibernation season without cold exposure...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28324156/molecular-characterization-of-two-rhesus-glycoproteins-from-the-euryhaline-freshwater-white-rimmed-stingray-himantura-signifer-and-changes-in-their-transcript-levels-and-protein-abundance-in-the-gills-kidney-and-liver-during-brackish-water-acclimation
#9
Cheng T Yeam, You R Chng, Jasmine L Y Ong, Wai P Wong, Shit F Chew, Yuen K Ip
Himantura signifer is a freshwater stingray which inhabits rivers in Southeast Asia. It is ammonotelic in fresh water, but retains the capacities of urea synthesis and ureosmotic osmoregulation to survive in brackish water. This study aimed to elucidate the roles of Rhesus glycoproteins (Rhgp), which are known to transport ammonia, in conserving nitrogen (N) in H. signifer during brackish water acclimation when N became limited resulting from increased hepatic urea synthesis. The complete coding sequence of rhbg from H...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28321493/the-costs-of-locomotor-activity-maximum-body-temperatures-and-the-use-of-torpor-during-the-active-season-in-edible-dormice
#10
Claudia Bieber, Jessica S Cornils, Franz Hoelzl, Sylvain Giroud, Thomas Ruf
Measuring T b during the active season can provide information about the timing of reproduction and the use of short bouts of torpor and may be used as a proxy for the locomotor activity of animals (i.e., maximum T b). This kind of information is especially important to understand life-history strategies and energetic costs and demands in hibernating mammals. We investigated T b throughout the active season in edible dormice (Glis glis), since they (i) have an expensive arboreal life-style, (ii) are known to show short bouts of torpor, and (iii) are adapted to pulsed resources (mast of beech trees)...
March 21, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28314947/seasonal-adaptations-in-energy-budgeting-in-the-primate-lepilemur-leucopus
#11
Janina Bethge, Bianca Wist, Eleanor Stalenberg, Kathrin Dausmann
The spiny forest of South Madagascar is one of the driest and most unpredictable habitats in Africa. The small-bodied, nocturnal primate Lepilemur leucopus lives in this harsh habitat with high diurnal and seasonal changes in ambient temperature. In this study, we investigated seasonal adaptions in energy budgeting of L. leucopus, which allow it to live under these conditions by measuring resting metabolic rate using open-flow respirometry. No signs of heterothermy were detected, and resting metabolic rate was significantly lower in the warmer wet season than in the colder dry season...
March 17, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28283796/white-sturgeon-acipenser-transmontanus-acid-base-regulation-differs-in-response-to-different-types-of-acidoses
#12
Ryan B Shartau, Dan W Baker, Colin J Brauner
White sturgeon (Acipenser transmontanus) completely protect intracellular tissue pH (pHi) despite large reductions in extracellular (blood) pH (pHe), termed preferential pHi regulation, in response to elevated environmental PCO2 (hypercarbia) and in general appear to be relatively resilient to stressors. Preferential pHi regulation is thought to be associated with hypercarbia tolerance in general, but has also recently been observed to protect pHi against metabolic acidoses induced by exhaustive exercise and anoxia in a tropical air breathing catfish...
March 11, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28283795/na-k-atpase-%C3%AE-1-subunit-associates-with-%C3%AE-1-subunit-modulating-a-higher-nka-in-hyposmotic-media-response-in-gills-of-euryhaline-milkfish-chanos-chanos
#13
Yau-Chung Hu, Keng-Fu Chu, Wen-Kai Yang, Tsung-Han Lee
The euryhaline milkfish (Chanos chanos) is a popular aquaculture species that can be cultured in fresh water, brackish water, or seawater in Southeast Asia. In gills of the milkfish, Na(+), K(+)-ATPase (i.e., NKA; sodium pump) responds to salinity challenges including changes in mRNA abundance, protein amount, and activity. The functional pump is composed of a heterodimeric protein complex composed of α- and β-subunits. Among the NKA genes, α1-β1 isozyme comprises the major form of NKA subunits in mammalian osmoregulatory organs; however, most studies on fish gills have focused on the α1 subunit and did not verify the α1-β1 isozyme...
March 10, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28283794/the-role-of-basking-in-the-development-of-endothermy-and-torpor-in-a-marsupial
#14
Chris B Wacker, Bronwyn M McAllan, Gerhard Körtner, Fritz Geiser
Marsupials have a slow rate of development and this allows a detailed examination of thermoregulatory developmental changes and stages. We quantified the cooling rates of marsupial dunnarts (Sminthopsis crassicaudata) at 40-56 days (d) old, and torpor and basking behaviour in animals given the option to bask in four age groups from 60 to 150 d. The development of thermoregulation was a continuum, but was characterised by three major thermoregulatory stages: (1) at 40 d, animals were unable to maintain a constant high body temperature during short-term cold exposure; (2) at 60 d, animals could maintain a high T b for the first part of the night at an ambient temperature of 15...
March 10, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28280923/na-k-atpase-response-to-salinity-change-and-its-correlation-with-fxyd11-expression-in-anguilla-marmorata
#15
Fenfei Liang, Li Li, Guosong Zhang, Shaowu Yin, Xiaolu Wang, Peng Li, Yihe Jia, Yayuan Wang, Li Wang, Xiaojun Wang
The Na(+)/K(+)-ATPase (NKA) is a primary electrogenic protein that promotes ion transport in teleosts. FXYD11 is a putative regulatory subunit of the NKA pump. The regulation of Na (+)/K (+) -ATPase and FXYD11 is of critical importance for osmotic homeostasis. To investigate the changes of the two genes under different salinity environments, we first identified NKA (AmNKAα1) and FXYD11 (AmFXYD11) in Anguilla marmorata, and then evaluated the mRNA levels of NKA and FXYD11 as well as the activity of NKA in the gill and kidney at different timepoints (0, 1, 3, 6, 12, 24, 48, 72, 96, and 360 h) under three salinity conditions-0‰ (fresh water: FW), 10‰ (brackish water: BW), and 25‰ (seawater: SW)...
March 9, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28261744/sex-differences-in-oxidative-stress-resistance-in-relation-to-longevity-in-drosophila-melanogaster
#16
S Niveditha, S Deepashree, S R Ramesh, T Shivanandappa
Gender differences in lifespan and aging are known across species. Sex differences in longevity within a species can be useful to understand sex-specific aging. Drosophila melanogaster is a good model to study the problem of sex differences in longevity since females are longer lived than males. There is evidence that stress resistance influences longevity. The objective of this study was to investigate if there is a relationship between sex differences in longevity and oxidative stress resistance in D. melanogaster...
March 6, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28251326/the-effect-of-starvation-and-re-feeding-on-vasotocinergic-and-isotocinergic-pathways-in-immature-gilthead-sea-bream-sparus-aurata
#17
Arleta Krystyna Skrzynska, Magdalena Gozdowska, Ewa Kulczykowska, Gonzalo Martínez-Rodríguez, Juan Miguel Mancera, Juan Antonio Martos-Sitcha
This study describes the responses of the vasotocinergic and isotocinergic systems to food deprivation and re-feeding processes in immature gilthead sea bream (Sparus aurata). The animals were subjected to the following experimental treatments: (1) normal feeding (control), (2) food deprivation for 21 days; and (3) re-feeding for 7 days, beginning 14 days after starvation. The animals were sampled at 0, 7, 14 and 21 days from the beginning of the trial. The pituitary and plasma arginine vasotocin (AVT) and isotocin (IT) levels and the hypothalamic pro-vasotocin and pro-isotocin mRNA expression levels were measured...
March 1, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28247055/camp-dependent-secretagogues-stimulate-the-nahco3-cotransporter-in-the-villous-epithelium-of-the-brushtail-possum-trichosurus-vulpecula
#18
Pin-Chun Chao, A Grant Butt
In the ileum of the brushtail possum, Trichosurus vulpecula, fluid secretion appears to be driven by electrogenic HCO3(-) secretion. Consistent with this, the cystic fibrosis transmembrane conductance regulator is expressed in the apical membrane of the ileal epithelial cells and the pancreatic or secretory variant of the NaHCO3 cotransporter in the basolateral membrane. This suggests that in the possum ileum, electrogenic HCO3(-) secretion is driven by basolateral NaHCO3 cotransporter (NBC) activity. To determine if the NBC contributes to HCO3(-) secretion in the possum ileum, intracellular pH (pHi) measurements in isolated villi were used to demonstrate NBC activity in the ileal epithelial cells and investigate the effect of cAMP-dependent secretagogues...
February 28, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28197776/effects-of-melanocortin-4-receptor-agonists-and-antagonists-on-expression-of-genes-related-to-reproduction-in-spotted-scat-scatophagus-argus
#19
Dong-Neng Jiang, Jian-Tao Li, Ya-Xiong Tao, Hua-Pu Chen, Si-Ping Deng, Chun-Hua Zhu, Guang-Li Li
Melanocortin-4 receptor (Mc4r) function related to reproduction in fish has not been extensively investigated. Here, we report on gene expression changes by real-time PCR following treatment with Mc4r agonists and antagonists in the spotted scat (Scatophagus argus). Using in vitro incubated hypothalamus, the Mc4r nonselective agonist NDP-MSH ([Nle(4), D-Phe(7)]-α-melanocyte stimulating hormone; 10(-6) M) and selective agonist THIQ (N-[(3R)-1, 2, 3, 4-Tetrahydroisoquinolinium-3-ylcarbonyl]- (1R)-1-(4-chlorobenzyl)-2-[4-cyclohexyl-4-(1H-1,2,4-triazol-1-ylmethyl) piperidin-1-yl]-2-oxoethylamine; 10(-7) M) significantly increased the expression of gnrh (Gonadotropin releasing hormone), while the Mc4r nonselective antagonist SHU9119 (Ac-Nle-[Asp-His-DPhe/DNal(2')-Arg-Trp-Lys]-NH2; 10(-6) M) and selective antagonist Ipsen 5i (compound 5i synthesized in Ipsen Research Laboratories; 10(-6) M) significantly inhibited gnrh expression after 3 h of incubation...
February 14, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28184997/molecular-characterization-of-myostatin-from-the-skeletal-muscle-of-the-african-lungfish-protopterus-annectens-and-changes-in-its-mrna-and-protein-expression-levels-during-three-phases-of-aestivation
#20
Jasmine L Y Ong, You R Chng, Biyun Ching, Xiu L Chen, Kum C Hiong, Wai P Wong, Shit F Chew, Yuen K Ip
African lungfishes can aestivate and remain torpid without food and water for years, but disuse muscle atrophy is not prominent during aestivation. This study aimed to clone myostatin (mstn/Mstn), a factor associated with disuse muscle atrophy in mammals, from the skeletal muscle of the African lungfish Protopterus annectens, and to determine its mRNA expression level and protein abundance therein during the induction, maintenance, and arousal phases of aestivation. The complete coding cDNA sequence of mstn comprised 1128 bp, encoding for 376 amino acids with an estimated molecular mass of 42...
February 9, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
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