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

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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
#1
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
#2
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
https://www.readbyqxmd.com/read/28180997/functional-characterization-of-a-novel-disaccharide-transporter-in-lobster-hepatopancreas
#3
Olivia Scheffler, Gregory A Ahearn
In animals, the accepted model of carbohydrate digestion and absorption involves reduction of disaccharides into the monosaccharides glucose, fructose, and galactose followed by their individual transmembrane transport into cells. In 2011, a gene for a distinct disaccharide sucrose transporter (SCRT) was found in Drosophila melanogaster and characterized in a yeast expression system. The purpose of the present investigation was to functionally identify and characterize a putative disaccharide transporter analog in the hepatopancreas of the American lobster, Homarus americanus...
February 8, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28161790/trade-offs-between-reproduction-and-health-in-free-ranging-african-striped-mice
#4
I Schoepf, N Pillay, C Schradin
Energy is limited and must be allocated among competing life-history traits. Reproduction is considered one of the most energetically demanding life-history stages. Therefore, the amount of energy an individual invests in reproduction might carry fitness costs through reduced energy allocation to other activities such as health maintenance. We investigated whether reproduction impacts health in the seasonally breeding African striped mouse (Rhabdomys pumilio). We measured health in individuals that reproduced (breeders) and individuals that did not reproduce (their adult offspring) and tested whether: (1) breeders' health before reproduction was similar to that of their offspring (representing a baseline); (2) breeders' health deteriorated after reproduction; (3) breeders' health after reproduction was worse than that of their offspring...
February 4, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28150179/detoxification-and-elimination-of-nicotine-by-nectar-feeding-birds
#5
S Lerch-Henning, E E Du Rand, S W Nicolson
Many dilute nectars consumed by bird pollinators contain secondary metabolites, potentially toxic chemicals produced by plants as defences against herbivores. Consequently, nectar-feeding birds are challenged not only by frequent water excess, but also by the toxin content of their diet. High water turnover, however, could be advantageous to nectar consumers by enabling them to excrete secondary metabolites or their transformation products more easily. We investigated how the alkaloid nicotine, naturally present in nectar of Nicotiana species, influences osmoregulation in white-bellied sunbirds Cinnyris talatala and Cape white-eyes Zosterops virens...
February 1, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28144740/hibernation-reduces-cellular-damage-caused-by-warm-hepatic-ischemia-reperfusion-in-ground-squirrels
#6
Jessica P Otis, Amanda C Pike, Jose R Torrealba, Hannah V Carey
During the hibernation season, livers from 13-lined ground squirrels (Ictidomys tridecemlineatus) are resistant to damage induced by ex vivo, cold ischemia-warm reperfusion (IR) compared with livers from summer squirrels or rats. Here, we tested the hypothesis that hibernation also reduces damage to ground squirrel livers in an in vivo, warm IR model, which more closely resembles complications associated with traumatic injury or surgical interventions. We also examined whether protection is mediated by two metabolites, inosine and biliverdin, that are elevated in ground squirrel liver during interbout arousals...
January 31, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28025707/phenotypic-plasticity-in-the-common-garden-snail-big-guts-and-heavier-mucus-glands-compete-in-snails-faced-with-the-dual-challenge-of-poor-diet-and-coarse-substrate
#7
Adam J Munn, Marguerite Treloar
Phenotypic plasticity allows animals to manage environmental challenges. Studies aimed at quantifying plasticity often focus on one challenge, such as diet, and one organ system, such the gastrointestinal tract, but this approach may not adequately reflect how plasticity could buffer multiple challenges. Thus, we investigated the outcomes of a dual challenge experiment that fed land snails either a high-fibre (low quality) or a low-fibre (high quality) diet, and simultaneously exercised them daily over 1.2 m on either a smooth surface of polyvinyl chloride (PVC) or a rough sandpaper...
December 26, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27987017/life-in-the-fat-lane-seasonal-regulation-of-insulin-sensitivity-food-intake-and-adipose-biology-in-brown-bears
#8
K S Rigano, J L Gehring, B D Evans Hutzenbiler, A V Chen, O L Nelson, C A Vella, C T Robbins, H T Jansen
Grizzly bears (Ursus arctos horribilis) have evolved remarkable metabolic adaptations including enormous fat accumulation during the active season followed by fasting during hibernation. However, these fluctuations in body mass do not cause the same harmful effects associated with obesity in humans. To better understand these seasonal transitions, we performed insulin and glucose tolerance tests in captive grizzly bears, characterized the annual profiles of circulating adipokines, and tested the anorectic effects of centrally administered leptin at different times of the year...
December 16, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27921142/intra-population-variability-of-ocean-acidification-impacts-on-the-physiology-of-baltic-blue-mussels-mytilus-edulis-integrating-tissue-and-organism-response
#9
L S Stapp, J Thomsen, H Schade, C Bock, F Melzner, H O Pörtner, G Lannig
Increased maintenance costs at cellular, and consequently organism level, are thought to be involved in shaping the sensitivity of marine calcifiers to ocean acidification (OA). Yet, knowledge of the capacity of marine calcifiers to undergo metabolic adaptation is sparse. In Kiel Fjord, blue mussels thrive despite periodically high seawater PCO2, making this population interesting for studying metabolic adaptation under OA. Consequently, we conducted a multi-generation experiment and compared physiological responses of F1 mussels from 'tolerant' and 'sensitive' families exposed to OA for 1 year...
December 5, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27915366/aging-has-the-opposite-effect-on-camp-and-cgmp-circadian-variations-in-rat-leydig-cells
#10
Aleksandar Z Baburski, Srdjan J Sokanovic, Silvana A Andric, Tatjana S Kostic
The Leydig cell physiology displays a circadian rhythm driven by a complex interaction of the reproductive axis hormones and circadian system. The final output of this regulatory process is circadian pattern of steroidogenic genes expression and testosterone production. Aging gradually decreases robustness of rhythmic testosterone secretion without change in pattern of LH secretion. Here, we analyzed effect of aging on circadian variation of cAMP and cGMP signaling in Leydig cells. Results showed opposite effect of aging on cAMP and cGMP daily variation...
December 3, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27744515/comparison-of-thermal-traits-of-polistes-dominula-and-polistes-gallicus-two-european-paper-wasps-with-strongly-differing-distribution-ranges
#11
Helmut Kovac, Helmut Käfer, Iacopo Petrocelli, Anton Stabentheiner
The two paper wasps, Polistes dominula and Polistes gallicus, are related species with strongly differing distribution ranges. We investigated thermal tolerance traits (critical thermal limits and metabolic response to temperature) to gain knowledge about physiological adaptations to their local climate conditions and to get evidence for the reasons of P. dominula's successful dispersion. Body and ambient temperature measurements at the nests revealed behavioural adaptations to microclimate. The species differed clearly in critical thermal minimum (P...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27744514/establishing-the-thermal-window-for-aerobic-scope-in-new-zealand-geoduck-clams-panopea-zelandica
#12
Dung V Le, Andrea C Alfaro, Norman L C Ragg, Zoë Hilton, Nick King
Geoduck clams (Panopea spp.) are the longest-lived and largest deep burrowing bivalve. Their unique morphology allows them to live buried in the sediment at depths of up to 1 m. The endemic New Zealand geoduck (Panopea zelandica Quoy and Gaimard, 1835) has recently been identified as a potential species for aquaculture. However, very little is known about the biology and physiology of this entirely subtidal geoduck species. Currently, the New Zealand geoduck fishery relies entirely upon wild harvests, but farms are expected to emerge as cultivation protocols are established...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27734149/torpor-and-basking-after-a-severe-wildfire-mammalian-survival-strategies-in-a-scorched-landscape
#13
Jaya K Matthews, Clare Stawski, Gerhard Körtner, Cassandra A Parker, Fritz Geiser
Wildfires can completely obliterate above-ground vegetation, yet some small terrestrial mammals survive during and after fires. As knowledge about the physiological and behavioural adaptations that are crucial for post-wildfire survival is scant, we investigated the thermal biology of a small insectivorous marsupial (Antechinus flavipes) after a severe forest fire. Some populations of antechinus survived the fire in situ probably by hiding deep in rocky crevices, the only fire-proof sites near where they were trapped...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27722773/expression-of-vegf-111-and-other-vegf-a-variants-in-the-rat-uterus-is-correlated-with-stage-of-pregnancy
#14
Camilla M Whittington, Kevin Danastas, Georges E Grau, Christopher R Murphy, Michael B Thompson
Vascular endothelial growth factor A is a major mediator of angiogenesis, a critically important process in vertebrate growth and development as well as pregnancy. Here we report for the first time the expression of a rare and unusually potent splice variant, VEGF 111 , in vivo in mammals. This variant has previously only been found in mammals in cultured human cells exposed to genotoxic agents. Our discovery of VEGF 111 in the uterus of both a eutherian (rat) and a marsupial (fat-tailed dunnart) suggests that the splice variant may be common to all mammals...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27695946/browning-of-subcutaneous-fat-and-higher-surface-temperature-in-response-to-phenotype-selection-for-advanced-endurance-exercise-performance-in-male-duhtp-mice
#15
J Brenmoehl, D Ohde, E Albrecht, C Walz, A Tuchscherer, A Hoeflich
For the assessment of genetic or conditional factors of fat cell browning, novel and polygenic animal models are required. Therefore, the long-term selected polygenic mouse line DUhTP originally established in Dummerstorf for high treadmill performance is used. DUhTP mice are characterized by increased fat accumulation in the sedentary condition and elevated fat mobilization during mild voluntary physical activity. In the present study, the phenotype of fat cell browning of subcutaneous fat and a potential effect on oral glucose tolerance, an indicator of metabolic health, were addressed in DUhTP mice...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27695931/modulation-of-digestive-enzyme-activities-in-the-avian-digestive-tract-in-relation-to-diet-composition-and-quality
#16
Kevin D Kohl, M Eugenia Ciminari, Juan G Chediack, James O Leafloor, William H Karasov, Scott R McWilliams, Enrique Caviedes-Vidal
In nature, birds are faced with variable food sources that may differ in composition (protein vs. carbohydrates) and quality (highly digestible material vs. indigestible fiber). Studies in passerine birds and some commercial poultry demonstrate that the gastrointestinal tract can respond to varying diet composition and quality by changing morphology and/or activities of digestive enzymes. However, studies in additional avian species are warranted to understand generalities of these trends. We first fed juvenile mallards (Anas platyrhynchos), chickens (Gallus gallus), and quails (Coturnix coturnix) on either high-carbohydrate or high-protein diets...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27686667/characterization-of-the-functional-and-anatomical-differences-in-the-atrial-and-ventricular-myocardium-from-three-species-of-elasmobranch-fishes-smooth-dogfish-mustelus-canis-sandbar-shark-carcharhinus-plumbeus-and-clearnose-skate-raja-eglanteria
#17
Julie Larsen, Peter Bushnell, John Steffensen, Morten Pedersen, Klaus Qvortrup, Richard Brill
We assessed the functional properties in atrial and ventricular myocardium (using isolated cardiac strips) of smooth dogfish (Mustelus canis), clearnose skate (Raja eglanteria), and sandbar shark (Carcharhinus plumbeus) by blocking Ca(2+) release from the sarcoplasmic reticulum (SR) with ryanodine and thapsigargin and measuring the resultant changes in contraction-relaxation parameters and the force-frequency relationship at 20 °C and 30 °C. We also examined ultrastructural differences with electron microscopy...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27678513/determinants-of-coronary-blood-flow-in-sandbar-sharks-carcharhinus-plumbeus
#18
Georgina K Cox, Richard W Brill, Kaitlin A Bonaro, Anthony P Farrell
The coronary circulation first appeared in the chordate lineage in cartilaginous fishes where, as in birds and mammals but unlike most teleost fishes, it supplies arterial blood to the entire myocardium. Despite the pivotal position of elasmobranch fishes in the evolution of the coronary circulation, the determinants of coronary blood flow have never been investigated in this group. Elasmobranch fishes are of special interest because of the morphological arrangement of their cardiomyocytes. Unlike teleosts, the majority of the ventricular myocardium in elasmobranch fishes is distant to the venous blood returning to the heart (i...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27672043/seasonal-changes-of-cholinergic-response-in-the-atrium-of-arctic-navaga-cod-eleginus-navaga
#19
Denis V Abramochkin, Matti Vornanen
Fishes of north-temperate latitudes exhibit marked seasonal changes in electrical excitability of the heart partly as an outcome of temperature-dependent changes in the density of major K(+) ion currents: delayed rectifiers (IKr, IKs) and background inward rectifier (IK1). In the arctic teleost, navaga cod (Eleginus navaga), IKr and IK1 are strongly up-regulated in winter. The current study tests the hypothesis that the ligand-gated K(+) current, the acetylcholine-activated inward rectifier, IKACh, is also modified by seasonal acclimatization in atrial myocytes of navaga...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/27638521/the-influence-of-natural-photoperiod-on-seasonal-torpor-expression-of-two-opportunistic-marsupial-hibernators
#20
James M Turner, Fritz Geiser
Many mammals use torpor throughout the year but the individual contributions of environmental variables to seasonal changes in torpor expression are often difficult to tease apart. In many mammals, torpor is most often used opportunistically in response to decreased ambient temperature (T a ) and food availability, but information on how seasonally changing photoperiod per se influences torpor patterns is scant. Therefore, we quantified patterns of torpor use in response to natural photoperiod in captive marsupial pygmy-possums held at near-constant T a with a stable food supply over a period of 19 months...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
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