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https://www.readbyqxmd.com/read/29142044/thermoregulatory-role-of-insensible-evaporative-water-loss-constancy-in-a-heterothermic-marsupial
#1
Christine Elizabeth Cooper, Philip Carew Withers
'Insensible' evaporative water loss of mammals has been traditionally viewed as a passive process, but recent studies suggest that insensible water loss is under regulatory control, although the physiological role of this control is unclear. We test the hypothesis that regulation of insensible water loss has a thermoregulatory function by quantifying for the first time evaporative water loss control, along with metabolic rate and body temperature, of a heterothermic mammal during normothermia and torpor. Evaporative water loss was independent of ambient relative humidity at ambient temperatures of 20 and 30°C, but not at 25°C or during torpor at 20°C...
November 2017: Biology Letters
https://www.readbyqxmd.com/read/29133226/the-effect-of-dietary-neonicotinoid-pesticides-on-non-flight-thermogenesis-in-worker-bumble-bees-bombus-terrestris
#2
Robert Potts, Rebecca M Clarke, Sophie E Oldfield, Lisa K Wood, Natalie Hempel de Ibarra, James E Cresswell
For bumble bees (genus Bombus), the capacity for non-flight thermogenesis is essential for two fundamental processes undertaken by adult workers, namely recovery from torpor after chilling and brood incubation. Farmland bees can be widely exposed to dietary residues of neurotoxic neonicotinoid insecticides that appear in the nectar and pollen of treated bee-attractive crops, which may harm them. An earlier study shows that dietary neonicotinoids cause complex alterations to thermoregulation in honey bees, but their effects on the thermogenic capabilities of individual bumble bees has been untested previously...
November 10, 2017: Journal of Insect Physiology
https://www.readbyqxmd.com/read/29125496/consciousness-in-hibernation-and-synthetic-torpor
#3
Matteo Cerri
While human hibernation would provide many advantages for medical applications and space exploration, the intrinsic risks of the procedure itself, as well as those involved if the procedure were to be misused, need to be assessed. Moreover, the distinctive brain state that is present during a hibernation-like state raises questions regarding the state of consciousness of the subject. Since, in animal studies, the cortical activity of this state differs from that of sleep, coma, or even general anesthesia, and resembles a sort of "slowed wakefulness", it is uncertain whether residual consciousness may still be present...
November 7, 2017: Journal of Integrative Neuroscience
https://www.readbyqxmd.com/read/29113989/cold-hearted-bats-uncoupling-of-heart-rate-and-metabolism-during-torpor-at-subzero-temperatures
#4
Shannon E Currie, Clare Stawski, Fritz Geiser
Many hibernating animals thermoregulate during torpor and defend their body temperature (Tb) below 10°C by an increase in metabolic rate. Above a critical temperature (Tcrit) animals usually thermoconform. We investigated the physiological responses above and below Tcrit for a small tree dwelling bat (Chalinolobus gouldii, ∼14 g) that is often exposed to subzero temperatures during winter. Through simultaneous measurement of heart rate (HR) and oxygen consumption (V̇O2) we show that the relationship between oxygen transport and cardiac function is substantially altered in thermoregulating torpid bats between 1 and -2°C, compared with thermoconforming torpid bats at mild ambient temperatures (Ta 5-20°C)...
November 7, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29108557/seasonal-energetics-and-torpor-use-in-north-american-flying-squirrels
#5
Megan N Olson, Jeff Bowman, Gary Burness
Seasonal cold temperatures require mammals to use morphological, behavioural, or physiological traits to survive periods of extreme cold and food shortage. Torpor is a physiological state that minimizes energy requirements by decreasing resting metabolic rate (MR) and body temperature (Tb). Many rodent species are capable of torpor, however, evidence in northern and southern flying squirrels (Glaucomys sabrinus and Glaucomys volans, respectively) has remained anecdotal. We experimentally attempted to induce torpor in wild-caught flying squirrels by lowering ambient temperature (Ta) and measuring MR using open-flow respirometry...
December 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29045417/effects-of-food-store-quality-on-hibernation-performance-in-common-hamsters
#6
Carina Siutz, Matthias Nemeth, Karl-Heinz Wagner, Ruth Quint, Thomas Ruf, Eva Millesi
Hibernating animals can adjust torpor expression according to available energy reserves. Besides the quantity, the quality of energy reserves could play an important role for overwintering strategies. Common hamsters are food-storing hibernators and show high individual variation in hibernation performance, which might be related to the quality of food hoards in the hibernacula. In this study, we tested the effects of food stores high in fat content, particularly polyunsaturated fatty acids (PUFAs), on hibernation patterns under laboratory conditions...
2017: PloS One
https://www.readbyqxmd.com/read/29038037/brain-inflammatory-cytokines-and-microglia-morphology-changes-throughout-hibernation-phases-in-syrian-hamster
#7
V Cogut, J J Bruintjes, B J L Eggen, E A van der Zee, R H Henning
Hibernators tolerate low metabolism, reduced cerebral blood flow and hypothermia during torpor without noticeable neuronal or synaptic dysfunction upon arousal. Previous studies found extensive changes in brain during torpor, including synaptic rearrangements, documented both morphologically and molecularly. As such adaptations may represent organ damage, we anticipated an inflammatory response in brain during specific hibernation phases. In this study, signs of inflammation in the brain were investigated in the Syrian hamster hippocampus (Mesocricetus Auratus) both during hibernation (torpor and arousal phases) and in summer and winter euthermic animals...
October 13, 2017: Brain, Behavior, and Immunity
https://www.readbyqxmd.com/read/29037383/regulation-of-pyruvate-dehydrogenase-pdh-in-the-hibernating-ground-squirrel-ictidomys-tridecemlineatus
#8
Sanoji Wijenayake, Shannon N Tessier, Kenneth B Storey
Pyruvate dehydrogenase (PDH) is a vital regulatory enzyme that catalyzes the conversion of pyruvate into acetyl-CoA and connects anaerobic glycolysis to aerobic TCA cycle. Post-translational inhibition of PDH activity via three serine phosphorylation sites (pS232, pS293, and pS300) regulate the metabolic flux through the TCA cycle, decrease glucose utilization, and facilitate lipid metabolism during times of nutrient deprivation. As metabolic readjustment is necessary to survive hibernation, the purpose of this study was to explore the post-translational regulation of pyruvate dehydrogenase and the expression levels of four mitochondrial serine/threonine kinases (PDHKs), during torpor-arousal cycles in liver, heart, and skeletal muscle of 13-lined ground squirrels...
October 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29023516/hypothalamic-control-systems-show-differential-gene-expression-during-spontaneous-daily-torpor-and-fasting-induced-torpor-in-the-djungarian-hamster-phodopus-sungorus
#9
Ceyda Cubuk, Hanna Markowsky, Annika Herwig
Djungarian hamsters are able to use spontaneous daily torpor (SDT) during the winter season as well as fasting-induced torpor (FIT) at any time of the year to cope with energetically challenging environmental conditions. Torpor is a state of severely reduced metabolism with a pronounced decrease in body temperature, which enables animals to decrease their individual energy requirements. Despite sharing common characteristics, such as reduced body mass before first torpor expression and depressed metabolism and body temperature during the torpid state, FIT and SDT differ in several physiological properties including torpor bout duration, minimal body temperature, fuel utilization and circadian organization...
2017: PloS One
https://www.readbyqxmd.com/read/29016625/state-dependent-metabolic-partitioning-and-energy-conservation-a-theoretical-framework-for-understanding-the-function-of-sleep
#10
Markus H Schmidt, Theodore W Swang, Ian M Hamilton, Janet A Best
Metabolic rate reduction has been considered the mechanism by which sleep conserves energy, similar to torpor or hibernation. This mechanism of energy savings is in conflict with the known upregulation (compared to wake) of diverse functions during sleep and neglects a potential role in energy conservation for partitioning of biological operations by behavioral state. Indeed, energy savings as derived from state-dependent resource allocations have yet to be examined. A mathematical model is presented based on relative rates of energy deployment for biological processes upregulated during either wake or sleep...
2017: PloS One
https://www.readbyqxmd.com/read/28918505/purification-and-characterization-of-skeletal-muscle-pyruvate-kinase-from-the-hibernating-ground-squirrel-urocitellus-richardsonii-potential-regulation-by-posttranslational-modification-during-torpor
#11
Ryan A V Bell, Kenneth B Storey
Ground squirrel torpor during winter hibernation is characterized by numerous physiological and biochemical changes, including alterations to fuel metabolism. During torpor, many tissues switch from carbohydrate to lipid catabolism, often by regulating key enzymes within glycolytic and lipolytic pathways. This study investigates the potential regulation of pyruvate kinase (PK), a key member of the glycolytic pathway, within the skeletal muscle of hibernating ground squirrels. PK was purified from the skeletal muscle of control and torpid Richardson's ground squirrels, and PK kinetics, structural stability, and posttranslational modifications were subsequently assessed...
September 16, 2017: Molecular and Cellular Biochemistry
https://www.readbyqxmd.com/read/28878736/commentary-torpor-the-rise-and-fall-of-3-monoiodothyronamine-from-brain-to-gut-from-gut-to-brain
#12
COMMENT
Annunziatina Laurino, Laura Raimondi
No abstract text is available yet for this article.
2017: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/28874726/remarkable-plasticity-of-na-k-atpase-ca-2-atpase-and-serca-contributes-to-muscle-disuse-atrophy-resistance-in-hibernating-daurian-ground-squirrels
#13
Quanling Guo, Xin Mi, Xiaoyong Sun, Xiaoyu Li, Weiwei Fu, Shenhui Xu, Qi Wang, Yasir Arfat, Huiping Wang, Hui Chang, Yunfang Gao
We investigated cytosolic calcium (Ca(2+)) and sarcoplasmic reticulum Ca(2+) regulation in skeletal muscle fibers of hibernating Daurian ground squirrels (Spermophilus dauricus), non-hibernating hindlimb-unloaded (HLU) squirrels, and HLU rats to clarify the molecular mechanisms involved in preventing muscle atrophy in hibernators. The Na(+), K(+)-ATPase and Ca(2+)-ATPase activities in the soleus muscle (SOL) of squirrels were maintained in hibernation, decreased during interbout arousal (IB-A), and increased to autumn/pre-hibernation (AUT/Pre-H) levels in torpor after interbout arousal (Post-IBA), whereas activities in the extensor digitorum longus muscle (EDL) were stable during hibernation, but increased during post-hibernation (Post-H)...
September 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28844867/integrated-stress-response-stimulates-fgf21-expression-systemic-enhancer-of-longevity
#14
REVIEW
Antero Salminen, Kai Kaarniranta, Anu Kauppinen
FGF21 is a multifunctional metabolic and stress hormone which is normally expressed in liver but cellular stress, e.g. mitochondrial or endoplasmic reticulum (ER) stress, can induce its expression and subsequent secretion from several mammalian tissues. The stress kinases of the integrated stress response (ISR) pathway stimulate the expression of FGF21 through the activation of ATF4 transcription factor, thus enhancing cellular stress resistance. The metabolic and stress-inducible transactivation mechanisms of FGF21 gene are mostly mediated through separate pathways...
December 2017: Cellular Signalling
https://www.readbyqxmd.com/read/28835446/white-nose-syndrome-increases-torpid-metabolic-rate-and-evaporative-water-loss-in-hibernating-bats
#15
Liam P McGuire, Heather W Mayberry, Craig K R Willis
Fungal diseases of wildlife typically manifest as superficial skin infections but can have devastating consequences for host physiology and survival. White-nose syndrome (WNS) is a fungal skin disease that has killed millions of hibernating bats in North America since 2007. Infection with the fungus Pseudogymnoascus destructans causes bats to rewarm too often during hibernation, but the cause of increased arousal rates remains unknown. Based on data from studies of captive and free-living bats, two mechanistic models have been proposed to explain disease processes in WNS...
August 23, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28806499/hibernating-little-pocket-mice-show-few-seasonal-changes-in-bone-properties
#16
Noellyn Pineda, Marjorie Owen, Claire Tucker, Samantha Wojda, Stanley Kitchen, Hal Black, Seth Donahue
Periods of disuse or physical inactivity increases bone porosity and decreases bone mineral density, resulting in a loss of bone mechanical competence in many animals. Although large hibernators like bears and marmots prevent bone loss during hibernation, despite long periods of physical inactivity, some small hibernators do lose bone during hibernation. Little pocket mice (Perognathus longimembris) remain underground during winter hibernation and undergo bouts of torpor and interbout arousals, but the torpor bout duration is shorter than other rodent hibernators...
August 14, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
https://www.readbyqxmd.com/read/28780752/regulation-of-smad-mediated-microrna-transcriptional-response-in-ground-squirrels-during-hibernation
#17
Cheng-Wei Wu, Kenneth B Storey
Mammalian hibernation is a state of dormancy that is used by some animals to survive through the unfavorable conditions of winter, and is characterized by coordinated suppression of basal metabolism that is supported by global inhibition of energy/ATP-consuming processes. In this study, we examine the regulation of the anti-proliferatory TGF-β/Smad transcription factor signaling pathway in the liver tissue of the hibernating 13-lined ground squirrel Ictidomys tridecemlineatus. The TGF-β/Smad signaling pathway is known to mediate cell cycle arrest through induction of cell cycle dependent kinase inhibitors, and more recently, has been shown to regulate a wide range of cellular processes via its control of microRNA biosynthesis...
August 5, 2017: Molecular and Cellular Biochemistry
https://www.readbyqxmd.com/read/28770069/sociality-influences-thermoregulation-and-roost-switching-in-a-forest-bat-using-ephemeral-roosts
#18
Danilo Russo, Luca Cistrone, Ivana Budinski, Giulia Console, Martina Della Corte, Claudia Milighetti, Ivy Di Salvo, Valentina Nardone, R Mark Brigham, Leonardo Ancillotto
In summer, many temperate bat species use daytime torpor, but breeding females do so less to avoid interferences with reproduction. In forest-roosting bats, deep tree cavities buffer roost microclimate from abrupt temperature oscillations and facilitate thermoregulation. Forest bats also switch roosts frequently, so thermally suitable cavities may be limiting. We tested how barbastelle bats (Barbastella barbastellus), often roosting beneath flaking bark in snags, may thermoregulate successfully despite the unstable microclimate of their preferred cavities...
July 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28766065/body-temperatures-of-hibernating-little-brown-bats-reveal-pronounced-behavioural-activity-during-deep-torpor-and-suggest-a-fever-response-during-white-nose-syndrome
#19
Heather W Mayberry, Liam P McGuire, Craig K R Willis
Hibernating animals use torpor [reduced body temperature (T b) and metabolic rate] to reduce energy expenditure during winter. Periodic arousals to normal T b are energetically expensive, so hibernators trade off arousal benefits against energetic costs. This is especially important for bats with white-nose syndrome (WNS), a fungal disease causing increased arousal frequency. Little brown bats (Myotis lucifugus) with WNS show upregulation of endogenous pyrogens and sickness behaviour. Therefore, we hypothesized that WNS should cause a fever response characterized by elevated T b...
August 1, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28746349/new-insights-on-the-regulation-of-the-adenine-nucleotide-pool-of-erythrocytes-in-mouse-models
#20
William G O'Brien, Han Shawn Ling, Zhaoyang Zhao, Cheng Chi Lee
The observation that induced torpor in non-hibernating mammals could result from an increased AMP concentration in circulation led our investigation to reveal that the added AMP altered oxygen transport of erythrocytes. To further study the effect of AMP in regulation of erythrocyte function and systemic metabolism, we generated mouse models deficient in key erythrocyte enzymes in AMP metabolism. We have previously reported altered erythrocyte adenine nucleotide levels corresponding to altered oxygen saturation in mice deficient in both CD73 and AMPD3...
2017: PloS One
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