Journal articles on the topic 'Hibernation'
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1
Takamatsu, N., K. Ohba, J. Kondo, N. Kondo, and T. Shiba. "Hibernation-associated gene regulation of plasma proteins with a collagen-like domain in mammalian hibernators." Molecular and Cellular Biology 13, no. 3 (March 1993): 1516–21. http://dx.doi.org/10.1128/mcb.13.3.1516-1521.1993.
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In mammals, hibernation is expressed by only a limited number of species, and the molecular mechanisms underlying hibernation are not well understood. Recently, we have found plasma proteins which disappear from blood specifically during hibernation in a mammalian hibernator, the chipmunk. Here, we report the cDNA cloning of these chipmunk hibernation-related proteins, HP-20, -25, and -27, and analyses of their expression. All three proteins contain a collagen-like domain near the N terminus and are highly homologous to each other. Their mRNAs were detected only in liver in nonhibernating chipmunks, and in hibernating chipmunks, the amounts were reduced to less than 1/10 of those in nonhibernating chipmunks, indicating that HP-20, -25, and -27 mRNA expression is regulated similarly in association with hibernation. Southern blot analyses of the squirrel family with each of chipmunk HP-20, -25, and -27 cDNA revealed that a nonhibernating species (tree squirrel) as well as another hibernating species (ground squirrel) retained the corresponding genes. However, their transcripts were detected only with the hibernating species, and in hibernating ground squirrels, their levels were greatly reduced compared with those in nonhibernating animals, as were the cases with the chipmunk. These observations are the first line of evidence for occurrence of hibernation-associated gene regulation. The results would indicate the commitment of HP-20, -25, and -27 to hibernation and support the idea that genetic controls are involved in mammalian hibernation.
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Takamatsu, N., K. Ohba, J. Kondo, N. Kondo, and T. Shiba. "Hibernation-associated gene regulation of plasma proteins with a collagen-like domain in mammalian hibernators." Molecular and Cellular Biology 13, no. 3 (March 1993): 1516–21. http://dx.doi.org/10.1128/mcb.13.3.1516.
Full textAbstract:
In mammals, hibernation is expressed by only a limited number of species, and the molecular mechanisms underlying hibernation are not well understood. Recently, we have found plasma proteins which disappear from blood specifically during hibernation in a mammalian hibernator, the chipmunk. Here, we report the cDNA cloning of these chipmunk hibernation-related proteins, HP-20, -25, and -27, and analyses of their expression. All three proteins contain a collagen-like domain near the N terminus and are highly homologous to each other. Their mRNAs were detected only in liver in nonhibernating chipmunks, and in hibernating chipmunks, the amounts were reduced to less than 1/10 of those in nonhibernating chipmunks, indicating that HP-20, -25, and -27 mRNA expression is regulated similarly in association with hibernation. Southern blot analyses of the squirrel family with each of chipmunk HP-20, -25, and -27 cDNA revealed that a nonhibernating species (tree squirrel) as well as another hibernating species (ground squirrel) retained the corresponding genes. However, their transcripts were detected only with the hibernating species, and in hibernating ground squirrels, their levels were greatly reduced compared with those in nonhibernating animals, as were the cases with the chipmunk. These observations are the first line of evidence for occurrence of hibernation-associated gene regulation. The results would indicate the commitment of HP-20, -25, and -27 to hibernation and support the idea that genetic controls are involved in mammalian hibernation.
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Brem, Ethan A., Alyssa D. McNulty, and William J. Israelsen. "Breeding and hibernation of captive meadow jumping mice (Zapus hudsonius)." PLOS ONE 16, no. 5 (May 10, 2021): e0240706. http://dx.doi.org/10.1371/journal.pone.0240706.
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Hibernating mammals exhibit unique metabolic and physiological phenotypes that have potential applications in medicine or spaceflight, yet our understanding of the genetic basis and molecular mechanisms of hibernation is limited. The meadow jumping mouse, a small North American hibernator, exhibits traits–including a short generation time–that would facilitate genetic approaches to hibernation research. Here we report the collection, captive breeding, and laboratory hibernation of meadow jumping mice. Captive breeders in our colony produced a statistically significant excess of male offspring and a large number of all-male and all-female litters. We confirmed that short photoperiod induced pre-hibernation fattening, and cold ambient temperature facilitated entry into hibernation. During pre-hibernation fattening, food consumption exhibited non-linear dependence on both body mass and temperature, such that food consumption was greatest in the heaviest animals at the coldest temperatures. Meadow jumping mice exhibited a strong circadian rhythm of nightly activity that was disrupted during the hibernation interval. We conclude that it is possible to study hibernation phenotypes using captive-bred meadow jumping mice in a laboratory setting.
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Storey, Kenneth B., and David A. Kelly. "Glycolysis and energetics in organs of hibernating mice (Zapus hudsonius)." Canadian Journal of Zoology 73, no. 1 (January 1, 1995): 202–7. http://dx.doi.org/10.1139/z95-023.
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Hibernation-induced changes in the concentrations of glycolytic intermediates, creatine phosphate, and adenylates were monitored in brain and skeletal muscle of the meadow jumping mouse, Zapus hudsonius, after both short (24 h) and long (5 – 7 d) periods of hibernation. Levels of hexose phosphates were greatly reduced in both organs after 24 h of hibernation, suggesting strong suppression of carbohydrate catabolism early in hibernation and indicating enzymatic regulation at the level of carbohydrate input into glycolysis. Both organs showed large changes in energy status during hibernation. Creatine phosphate content declined progressively over time to levels in 5 – 7 d hibernating animals that were 50 and 60% of control values in brain and muscle, respectively. Total adenylates and ATP levels also fell sharply during hibernation, but the net effect of changing adenylate levels on energy charge was minimal; energy charge was 0.94 in both organs of control animals and fell to 0.88 –0.90 in hibernating animals. The overall reduction in the pool sizes of phosphagen and adenylates in organs of hibernating animals may be one factor involved in metabolic suppression during hibernation.
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Taylor, Bernadette, Erika Hanson, Bayan Shaheen, and Scott Cooper. "Changes in plasma angiopoietin-like protein 2 levels and macrophage migration associated with hibernation in thirteen-lined ground squirrels (CAM5P.232)." Journal of Immunology 192, no. 1_Supplement (May 1, 2014): 180.3. http://dx.doi.org/10.4049/jimmunol.192.supp.180.3.
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Abstract Thirteen-lined ground squirrels in the northern United States hibernate from around late September until March. In late summer they gain a substantial amount of fat that is gradually expended as fuel over the course of hibernation. Immune system changes during hibernation include a 90% drop in circulating leukocytes and a reduction in immune responsiveness. Adipose tissue in obese humans is associated with changes in leukocyte migration including macrophage infiltration. This study explored an adipose-associated inflammatory protein, angiopoeitin-like protein 2 (ANGPTL2) as a potential mediator of leukocyte migration in hibernating ground squirrels. Plasma ANGPTL2 in eight ground squirrels was measured by quantitative Western blot at non-hibernating, entering hibernation, hibernating, interbout arousal and post arousal time points. ANGPTL2 levels were higher in hibernation than all other time points and were significantly higher in hibernation compared to interbout arousal or post arousal time points. Macrophages were detected in adipose tissue of hibernating ground squirrels using a ground squirrel macrophage specific monoclonal antibody in immunoperoxidase stained frozen sections. Macrophage-staining in the spleen appeared to be unusually dense in venous sinuses of hibernating compared to non-hibernating squirrels.
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Oro, Daniel, and Lídia Freixas. "Flickering body temperature anticipates criticality in hibernation dynamics." Royal Society Open Science 8, no. 1 (January 13, 2021): 201571. http://dx.doi.org/10.1098/rsos.201571.
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Hibernation has been selected for increasing survival in harsh climatic environments. Seasonal variability in temperature may push the body temperatures of hibernating animals across boundaries of alternative states between euthermic temperature and torpor temperature, typical of either hibernation or summer dormancy. Nowadays, wearable electronics present a promising avenue to assess the occurrence of criticality in physiological systems, such as body temperature fluctuating between attractors of activity and hibernation. For this purpose, we deployed temperature loggers on two hibernating edible dormice for an entire year and under Mediterranean climate conditions. Highly stochastic body temperatures with sudden switches over time allowed us to assess the reliability of statistical leading indicators to anticipate tipping points when approaching a critical transition. Hibernation dynamics showed flickering, a phenomenon occurring when a system rapidly moves back and forth between two alternative attractors preceding the upcoming major regime shift. Flickering of body temperature increased when the system approached bifurcations, which were also anticipated by several metric- and model-based statistical indicators. Nevertheless, some indicators did not show a pattern in their response, which suggests that their performance varies with the dynamics of the biological system studied. Gradual changes in air temperature drove transient between states of hibernation and activity, and also drove hysteresis. For hibernating animals, hysteresis may increase resilience when ending hibernation earlier than the optimal time, which may occur in regions where temperatures are sharply rising, especially during winter. Temporal changes in early indicators of critical transitions in hibernation dynamics may help to understand the effects of climate on evolutionary life histories and the plasticity of hibernating organisms to cope with shortened hibernation due to global warming.
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Sonoyama, Kei, Reiko Fujiwara, Naoki Takemura, Toru Ogasawara, Jun Watanabe, Hiroyuki Ito, and Tatsuya Morita. "Response of Gut Microbiota to Fasting and Hibernation in Syrian Hamsters." Applied and Environmental Microbiology 75, no. 20 (August 21, 2009): 6451–56. http://dx.doi.org/10.1128/aem.00692-09.
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ABSTRACT Although hibernating mammals wake occasionally to eat during torpor, this period represents a state of fasting. Fasting is known to alter the gut microbiota in nonhibernating mammals; therefore, hibernation may also affect the gut microbiota. However, there are few reports of gut microbiota in hibernating mammals. The present study aimed to compare the gut microbiota in hibernating torpid Syrian hamsters with that in active counterparts by using culture-independent analyses. Hamsters were allocated to either torpid, fed active, or fasted active groups. Hibernation was successfully induced by maintaining darkness at 4°C. Flow cytometry analysis of cecal bacteria showed that 96-h fasting reduced the total gut bacteria. This period of fasting also reduced the concentrations of short chain fatty acids in the cecal contents. In contrast, total bacterial numbers and concentrations of short chain fatty acids were unaffected by hibernation. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments indicated that fasting and hibernation modulated the cecal microbiota. Analysis of 16S rRNA clone library and species-specific real-time quantitative PCR showed that the class Clostridia predominated in both active and torpid hamsters and that populations of Akkermansia muciniphila, a mucin degrader, were increased by fasting but not by hibernation. From these results, we conclude that the gut microbiota responds differently to fasting and hibernation in Syrian hamsters.
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Kim, MW, DH Jeong, and SC Yeon. "Hibernation behaviour and ethogram of captive Asiatic black bear (Ursus thibetanus)." Veterinární Medicína 65, No. 1 (January 29, 2020): 1–7. http://dx.doi.org/10.17221/135/2019-vetmed.
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This study was undertaken to create an Asiatic black bear (Ursus thibetanus; ABB) ethogram during hibernation and to describe the time budget of hibernating behaviours in ABB. Seven captive adult ABB were included in the study and began hibernation between October and December. Data were collected for three consecutive years (2013–2015) during ABB hibernation (total 169 days) using closed-circuit television. During the study, we observed 21 distinct behaviours in hibernating ABB (4 least active and 17 active behaviours). Five bears started hibernation less than seven days after feeding cessation, and by the end of one week, all bears hibernated. The most commonly observed behaviour was “sleep curling inside nest”, and “nest maintenance” was the second most common behaviour. Among the active behaviours, “sitting in the nest”, “change stance”, “drinking and eating” were mostly shown as documented during the observation times. Our results provide new insights into the hibernating behaviours of ABB.
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Wermundsen, Terhi, and Yrjö Siivonen. "Seasonal variation in use of winter roosts by five bat species in south-east Finland." Open Life Sciences 5, no. 2 (April 1, 2010): 262–73. http://dx.doi.org/10.2478/s11535-009-0063-8.
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AbstractWe studied seasonal variation in the use of winter roosts by five bat species (Eptesicus nilssonii, Myotis brandtii/mystacinus, Myotis daubentonii and Plecotus auritus) in south-east Finland during the winters of 2003/2004 and 2004/2005. At the beginning of the bat hibernation season all species used higher temperatures and humidity than by the season’s end. Hibernacula were at their coldest in mid-hibernation season and became warmer towards the end of the season. However, no species hibernated in warmer locations at the end of the season than in mid-season. Results suggest that bats tend to use different strategies throughout the hibernation season, minimizing the cost of hibernation early in the season by hibernating in warmer locations and minimizing energy expenditure later in the season by hibernating in colder locations. M. brandtii/mystacinus were found in locations with stable temperature and humidity, moving to increasingly stable conditions (chambers, crevices, clusters, ceiling) towards spring. All other species hibernated in more variable microclimates throughout the hibernation season.
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McInerney, Emma P., Aimee J. Silla, and Phillip G. Byrne. "Carotenoid supplementation affects the post-hibernation performance of southern corroboree frogs." Behaviour 157, no. 2 (February 6, 2020): 121–42. http://dx.doi.org/10.1163/1568539x-00003584.
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Abstract Many animals hibernate to survive winter conditions, however, arousal from hibernation generates reactive oxygen species (ROS) that can cause oxidative stress. Dietary antioxidants, like carotenoids, may reduce oxidative stress during arousal from hibernation, and assist with post-hibernation recovery and performance. We tested the effect of carotenoid supplementation on exercise performance (escape-response and activity) in southern corroboree frogs (Pseudophryne corroboree) following initial arousal from hibernation (24–48 h post-arousal) and post-recovery (six weeks post-hibernation). Carotenoids did not affect performance following initial arousal. However, carotenoids improved escape-response six weeks post-hibernation, with carotenoid-supplemented frogs hopping faster and further in their first hop than unsupplemented frogs. Carotenoids also affected post-recovery activity, with carotenoid-supplemented frogs being less mobile than unsupplemented frogs. Carotenoids may affect post-hibernation performance by reducing oxidative stress or by increasing diet quality. Our study provides novel evidence for an effect of carotenoids on performance post-hibernation and highlights the importance of nutrition to hibernating organisms.
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Turbill, Christopher, Claudia Bieber, and Thomas Ruf. "Hibernation is associated with increased survival and the evolution of slow life histories among mammals." Proceedings of the Royal Society B: Biological Sciences 278, no. 1723 (March 30, 2011): 3355–63. http://dx.doi.org/10.1098/rspb.2011.0190.
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Survival probability is predicted to underlie the evolution of life histories along a slow–fast continuum. Hibernation allows a diverse range of small mammals to exhibit seasonal dormancy, which might increase survival and consequently be associated with relatively slow life histories. We used phylogenetically informed GLS models to test for an effect of hibernation on seasonal and annual survival, and on key attributes of life histories among mammals. Monthly survival was in most cases higher during hibernation compared with the active season, probably because inactivity minimizes predation. Hibernators also have approximately 15 per cent higher annual survival than similar sized non-hibernating species. As predicted, we found an effect of hibernation on the relationships between life history attributes and body mass: small hibernating mammals generally have longer maximum life spans (50% greater for a 50 g species), reproduce at slower rates, mature at older ages and have longer generation times compared with similar-sized non-hibernators. In accordance with evolutionary theories, however, hibernating species do not have longer life spans than non-hibernators with similar survival rates, nor do they have lower reproductive rates than non-hibernators with similar maximum life spans. Thus, our combined results suggest that (i) hibernation is associated with high rates of overwinter and annual survival, and (ii) an increase in survival in hibernating species is linked with the coevolution of traits indicative of relatively slow life histories.
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Hittel, Dustin S., and Kenneth B. Storey. "Differential expression of mitochondria-encoded genes in a hibernating mammal." Journal of Experimental Biology 205, no. 11 (June 1, 2002): 1625–31. http://dx.doi.org/10.1242/jeb.205.11.1625.
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SUMMARYA cDNA library constructed from kidney of the thirteen-lined squirrel, Spermophilus tridecemlineatus, was differentially screened for genes that were upregulated during hibernation. A clone encoding cytochrome c oxidase subunit 1 was found and confirmed to have been upregulated by northern blotting. Differential expression of Cox1 mRNA occurred in multiple organs during hibernation; in hibernating animals transcript levels were twofold higher in kidney and fourfold higher in heart and brown adipose tissue than in euthermic animals, but were unchanged in skeletal muscle. Transcript levels of mitochondrial-encoded ATP synthase 6/8 were similarly upregulated in these tissues whereas transcript levels of the nuclear encoded subunits Cox4 and ATP synthase α did not change during hibernation. Immunoblot analysis revealed a 2.4-fold increase in Cox 1 protein and a slight decrease in Cox 4 protein in kidney of hibernating squirrels, compared with euthermic controls. Hibernating mammals may increase the expression of the mitochondrial genome in general, and Cox1specifically, to prevent or minimize the damage to the electron transport chain caused by the cold and ischemia experienced during a hibernation bout.
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SAU, ASHOK K., ADITYA K. TANWAR, and MUKESH K. DHILLON. "Hibernation induced biochemical changes in spotted stem borer <i>Chilo partellus</i>." Indian Journal of Agricultural Sciences 93, no. 12 (December 19, 2023): 1344–49. http://dx.doi.org/10.56093/ijas.v93i12.136715.
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Spotted stem borer, Chilo partellus (Swinhoe) is one of the most destructive pests of sorghum and maize, and undergoes hibernation during harsh winters. Several aspects of diapause have been studied, however metabolic and biochemical processes underlying hibernation remain poorly understood in C. partellus. Present studies carried out during 2020–22 at ICAR-Indian Agricultural Research Institute, New Delhi deciphered the variations in nutritional biochemicals, digestive and stress enzymes, cryoprotectants in the hibernation and in non-hibernating larvae and pupae of C. partellus. These studies revealed that the total lipids and proteins were significantly greater during pre- hibernation and hibernation, and sugars were greater in non-hibernation larvae. Glycogen content was greater in pre- hibernation, and sorbitol, trehalose and glucitol contents consistently increased from pre-hibernation to hibernation stages in comparison to non-hibernation larvae of C. partellus. Total sugar and sorbitol contents decreased, while total protein, trehalose and glucitol increased, in post-hibernation than the non-hibernation pupae of C. partellus. Activities of ascorbic acid, lipid peroxidation, total antioxidant, catalase and superoxide dismutase were significantly greater during hibernation followed by pre-hibernation as compared to non-hibernation larvae, while the reverse was the case with protease activity. Ascorbic acid, lipid peroxidation, total antioxidant and catalase activities were greater in post-hibernation as compared to non-hibernation pupae of C. partellus. However, glutathione S-transferase activity was greater in the non-hibernation larvae and pupae than the hibernation larvae and post-hibernation pupae of C. partellus. These findings can be useful to design newer management strategies keeping in view the weak links like the state of nutritional metabolism and oxidative stress tolerance due to diapause in C. partellus.
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Srere, H. K., D. Belke, L. C. Wang, and S. L. Martin. "alpha 2-Macroglobulin gene expression during hibernation in ground squirrels is independent of acute phase response." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 268, no. 6 (June 1, 1995): R1507—R1512. http://dx.doi.org/10.1152/ajpregu.1995.268.6.r1507.
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alpha 2-Macroglobulin, a major acute phase reactant in many species, increases in the Richardson's ground squirrel (Spermophilus richarsonii) during hibernation at the level of both mRNA and protein. To determine if the pattern of liver gene expression known as the acute phase response is elicited as a normal part of the physiological adaptation of hibernation, acute phase reactants were identified in the Richardson's ground squirrel and were then assayed for changes in mRNA expression in the livers of active and hibernating ground squirrels. Our data demonstrate that alpha 1-antitrypsin, alpha 2-macroglobulin, ceruloplasmin, C-reactive protein, and serum amyloid A are acute phase reactants in the Richardson's ground squirrel. Of these, only alpha 2-macroglobulin (alpha 2M) mRNA increases during hibernation, demonstrating that the entire acute phase response is not elicited as a part of the adaptation for hibernation. Alternatively, data from blood clotting assays of serum from active and hibernating animals support a role for the increase in alpha 2M protein during hibernation in decreasing the coagulative properties of the blood.
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McGee-Lawrence, Meghan E., Hannah V. Carey, and Seth W. Donahue. "Mammalian hibernation as a model of disuse osteoporosis: the effects of physical inactivity on bone metabolism, structure, and strength." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 295, no. 6 (December 2008): R1999—R2014. http://dx.doi.org/10.1152/ajpregu.90648.2008.
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Reduced skeletal loading typically leads to bone loss because bone formation and bone resorption become unbalanced. Hibernation is a natural model of musculoskeletal disuse because hibernating animals greatly reduce weight-bearing activity, and therefore, they would be expected to lose bone. Some evidence suggests that small mammals like ground squirrels, bats, and hamsters do lose bone during hibernation, but the mechanism of bone loss is unclear. In contrast, hibernating bears maintain balanced bone remodeling and preserve bone structure and strength. Differences in the skeletal responses of bears and smaller mammals to hibernation may be due to differences in their hibernation patterns; smaller mammals may excrete calcium liberated from bone during periodic arousals throughout hibernation, leading to progressive bone loss over time, whereas bears may have evolved more sophisticated physiological processes to recycle calcium, prevent hypercalcemia, and maintain bone integrity. Investigating the roles of neural and hormonal control of bear bone metabolism could give valuable insight into translating the mechanisms that prevent disuse-induced bone loss in bears into novel therapies for treating osteoporosis.
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Jiang, Shanfeng, Shupan Guo, Wei Xue, Huiping Wang, Nandu Goswami, and Yunfang Gao. "Seasonal oxidative capacity of skeletal muscles in hibernating Daurian ground squirrels (Spermophilus dauricus)." Canadian Journal of Zoology 93, no. 8 (August 2015): 593–98. http://dx.doi.org/10.1139/cjz-2015-0027.
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We investigated the mechanism of high oxidative capacity of skeletal muscles in hibernating Daurian ground squirrels (Spermophilus dauricus Brandt, 1843). Myoglobin (Mb) levels, as well as citrate synthase and lactate dehydrogenase (LDH) activities, were measured by spectrophotometry. Mb content in the soleus (SOL) muscle lasted from the beginning of hibernation to spring. Mb content in SOL was 87% higher in the hibernating group than in the summer group. Mb content in the extensor digitorum longus (EDL) muscle stayed at similar levels during the different periods of the year. Citrate synthase activity in SOL was 30% higher in the hibernating group than in the summer group. Meanwhile, citrate synthase activity in EDL did not change during hibernation. LDH activity in SOL was not different between the hibernating group and the summer active group, whereas LDH activity in EDL increased significantly (up to 11%) in the 2 days arousal after hibernation group compared with the hibernating group. We conclude that high oxidative capacity is provided by increased oxygen storage capacity of slow-twitch muscle fibers rather than from fast-twitch muscle fibers in hibernating animals.
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He, Yue, Yong Kong, Rongrong Yin, Huajian Yang, Jie Zhang, Huiping Wang, and Yunfang Gao. "Remarkable Plasticity of Bone Iron Homeostasis in Hibernating Daurian Ground Squirrels (Spermophilus dauricus) May Be Involved in Bone Maintenance." International Journal of Molecular Sciences 23, no. 24 (December 13, 2022): 15858. http://dx.doi.org/10.3390/ijms232415858.
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Iron overload is an independent risk factor for disuse osteoporosis. Hibernating animals are natural models of anti-disuse osteoporosis; however, whether iron metabolism is involved in bone adaptation and maintenance during hibernation is unclear. To investigate this question, Daurian ground squirrels (Spermophilus dauricus) (n = 5–6/group) were used to study changes in bone iron metabolism and its possible role in anti-disuse osteoporosis during hibernation. Iron content in the femur and liver first decreased in the torpor group (vs. summer group, −66.8% and −25.8%, respectively), then recovered in the post-hibernation group, suggesting remarkable plasticity of bone iron content. The expression of ferritin in the femur and hepcidin in the liver also initially decreased in the torpor group (vs. summer group, −28.5% and −38.8%, respectively), then increased in the inter-bout arousal (vs. torpor group, 126.2% and 58.4%, respectively) and post-hibernation groups (vs. torpor group, 153.1% and 27.1%, respectively). In conclusion, bone iron metabolism in hibernating Daurian ground squirrels showed remarkable plasticity, which may be a potential mechanism to avoid disuse bone loss during extended periods of inactivity. However, the specific location of iron during low-iron hibernation and the source of iron in post-hibernation recovery need to be further explored.
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Kitao, Naoya, and Masaaki Hashimoto. "Increased thermogenic capacity of brown adipose tissue under low temperature and its contribution to arousal from hibernation in Syrian hamsters." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 302, no. 1 (January 2012): R118—R125. http://dx.doi.org/10.1152/ajpregu.00053.2011.
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Brown adipose tissue (BAT) is thought to play a significant physiological role during arousal when body temperature rises from the extremely low body temperature that occurs during hibernation. The dominant pathway of BAT thermogenesis occurs through the β3-adrenergic receptor. In this study, we investigated the role of the β3-adrenergic system in BAT thermogenesis during arousal from hibernation both in vitro and in vivo. Syrian hamsters in the hibernation group contained BAT that was significantly greater in overall mass, total protein, and thermogenic uncoupling protein-1 than BAT from the warm-acclimated group. Although the ability of the β3-agonist CL316,243 to induce BAT thermogenesis at 36°C was no different between the hibernation and warm-acclimated groups, its maximum ratio over the basal value at 12°C in the hibernation group was significantly larger than that in the warm-acclimated group. Forskolin stimulation at 12°C produced equivalent BAT responses in these two groups. In vivo thermogenesis was assessed with the arousal time determined by the time course of BAT temperature or heart rate. Stimulation of BAT by CL316,243 significantly shortened the time of arousal from hibernation compared with that induced by vehicle alone, and it also induced arousal in deep hibernating animals. The β3-antagonist SR59230A inhibited arousal from hibernation either in part or completely. These results suggest that BAT in hibernating animals has potent thermogenic activity with a highly effective β3-receptor mechanism at lower temperatures.
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Heusch, Gerd, Rainer Schulz, and Shahbudin H. Rahimtoola. "Myocardial hibernation: a delicate balance." American Journal of Physiology-Heart and Circulatory Physiology 288, no. 3 (March 2005): H984—H999. http://dx.doi.org/10.1152/ajpheart.01109.2004.
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The pathophysiology of myocardial hibernation is characterized as a situation of reduced regional contractile function distal to a coronary artery stenosis that recovers after removal of the coronary stenosis. A subacute “downregulation” of contractile function in response to reduced regional myocardial blood flow exists, which normalizes regional energy and substrate metabolism but does not persist for more than 12–24 h. Chronic hibernation develops in response to one or more episodes of myocardial ischemia-reperfusion, possibly progressing from repetitive stunning with normal blood flow to hibernation with reduced blood flow. An upregulation of a protective gene program is seen in hibernating myocardium, putting it into the context of preconditioning. The morphology of hibernating myocardium is characterized by both adaptive and degenerative features.
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Wilbur, Sara M., Cody E. Deane, Greg A. Breed, C. Loren Buck, Cory T. Williams, and Brian M. Barnes. "Survival estimates of free-living arctic ground squirrels (Urocitellus parryii): effects of sex and biologging." Canadian Journal of Zoology 100, no. 4 (April 2022): 251–60. http://dx.doi.org/10.1139/cjz-2021-0156.
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Hibernation is associated with long lifespan: on average, hibernating mammals live 15% longer than nonhibernators of equivalent mass. We investigated how survival varies with sex, season, and the deployment of biologgers in arctic ground squirrels (Urocitellus parryii (Richardson, 1825)), a widely distributed northern hibernator. The duration of hibernation in arctic ground squirrels differs markedly by sex: females hibernate 30% longer each year than males, a behavioural trait that could positively affect female survival. Additionally, males engage in aggressive territorial and food cache defense in spring and fall, which may decrease survival in this sex. From 13 years of mark–recapture data, we estimated apparent survival of arctic ground squirrels in Arctic Alaska (USA) using Cormack–Jolly–Seber models in program MARK. We found that females had higher annual survival ([Formula: see text] (95% confidence interval (CI): 0.469, 0.913)) than males ([Formula: see text] (95% CI: 0.416, 0.670)), with a maximum observed lifespan (10 years) that exceeded that of males (6 years). We also show that biologger use and implantation did not significantly impact survival. Quantifying basic arctic ground squirrel demographics from this well-studied population illustrates how sex-specific hibernation parameters may influence lifespan differences in male and female arctic ground squirrels and provides support for the safety of biologging devices.
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Sato, Iwao, Kiyoshi Konishi, Masataka Sunohara, and Akiko Mikami. "Enzyme activities and morphology of Japanese brown frog (Rana japonica) mitochondria in the tibialis anterior muscle during hibernation and active life." Canadian Journal of Zoology 79, no. 7 (July 1, 2001): 1316–21. http://dx.doi.org/10.1139/z01-083.
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Enzyme activities in the respiratory chain, as well as the structure and numbers of mitochondria of the tibialis anterior muscle, during hibernation were compared with those of normally active muscle in the Japanese brown frog (Rana japonica). Morphological examination using an electron microscope showed that during hibernation, mitochondria were larger and longer and had clearly distinguishable outer and inner membranes with developed cristae. A significantly greater number of glycogen granules was found in the tibialis anterior muscle of hibernating frogs. The average cross-sectional area (CSA) of muscle fiber was much smaller in the samples from hibernating frogs than those from active frogs. The numbers of mitochondria per CSA were also much higher during hibernation than during active life. Measurements of the enzyme activities of succinate dehydrogenase, NADH-ferricyanide reductase, and succinate-O2 and NADH-O2 oxidoreductases showed different profiles between hibernation and active life. That is, all four activities were significantly higher during hibernation than during active life. Taken together, the results obtained suggest that the seasonal variations in the activities of respiratory-chain systems may be related to the seasonal morphological changes in muscle mitochondria in R. japonica.
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Turbill, Christopher, Thomas Ruf, Steve Smith, and Claudia Bieber. "Seasonal variation in telomere length of a hibernating rodent." Biology Letters 9, no. 2 (April 23, 2013): 20121095. http://dx.doi.org/10.1098/rsbl.2012.1095.
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Small hibernating rodents have greater maximum lifespans and hence appear to age more slowly than similar-sized non-hibernators. We tested for a direct effect of hibernation on somatic maintenance and ageing by measuring seasonal changes in relative telomere length (RTL) in the edible dormouse Glis glis . Average RTL in our population did not change significantly over the hibernation season, and a regression model explaining individual variation in post-hibernation RTL suggested a significant negative effect of the reduction in body mass over the inactive hibernation period (an index of time spent euthermic), supporting the idea that torpor slows ageing. Over the active season, RTL on average decreased in sub-adults but increased in adults, supporting previous findings of greater telomere shortening at younger ages. Telomere length increase might also have been associated with reproduction, which occurred only in adults. Our study reveals how seasonal changes in physiological state influence the progress of life-history traits, such as somatic maintenance and ageing, in a small hibernating rodent.
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Bu, Rongping, Zihao Ye, and Haitao Shi. "Hibernation in Reeves’ Turtles (Mauremys reevesii) in Qichun County, Hubei Province, China: Hibernation Beginning and End and Habitat Selection." Animals 12, no. 18 (September 14, 2022): 2411. http://dx.doi.org/10.3390/ani12182411.
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Hibernation protects turtles from extreme winter conditions. Reeves’ turtle (Mauremys reevesii) is a medium-sized aquatic turtle that lives in freshwater habitats in lowland areas with still or slowly moving water. Currently, little is known regarding its overwintering behavior. In the current study, 20 Reeves’ turtles from the wild were investigated using radiotelemetry in the field to determine the beginning and end dates of, and habitat selected for, hibernation. Hibernation began in late October 2021 and arousal began in March 2022. Reeves’ turtles do not appear to be limited in their selection of suitable hibernation habitats, which included fish ponds, abandoned ponds (ponds not being used for farming), marshes, and abandoned fields (fields not being used for farming). In the aquatic hibernation habitats, only herbage cover was significantly different between the selected and random habitats (t = 2.525, df = 9, p = 0.033). In the terrestrial hibernation habitats, there were significant differences in the canopy (Z = −2.201, p = 0.028), slope gradient (Z = −2.032, p = 0.042), herbage cover (Z = −2.379, p = 0.017), and distance from the habitat edge (Z = −2.524, p = 0.012) between the selected and random habitats. This indicates that Reeves’ turtles prefer to hibernate at the soft edges of flat habitats with low canopy and high herbage cover when hibernating in terrestrial habitats and prefer to hibernate at sites with high herbage cover when hibernating in aquatic habitats. To the best of our knowledge, this is the first study to investigate hibernation in wild Reeves’ turtles in the field, and the results identify key ecological variables correlated with habitat selection during hibernation. This knowledge could inform local conservation measures related to farming activities.
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Quinones, Quintin J., Zhiquan Zhang, Qing Ma, Michael P. Smith, Erik Soderblom, M. Arthur Moseley, James Bain, et al. "Proteomic Profiling Reveals Adaptive Responses to Surgical Myocardial Ischemia–Reperfusion in Hibernating Arctic Ground Squirrels Compared to Rats." Anesthesiology 124, no. 6 (June 1, 2016): 1296–310. http://dx.doi.org/10.1097/aln.0000000000001113.
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Abstract Background Hibernation is an adaptation to extreme environments known to provide organ protection against ischemia–reperfusion (I/R) injury. An unbiased systems approach was utilized to investigate hibernation-induced changes that are characteristic of the hibernator cardioprotective phenotype, by comparing the myocardial proteome of winter hibernating arctic ground squirrels (AGS), summer active AGS, and rats subjected to I/R, and further correlating with targeted metabolic changes. Methods In a well-defined rodent model of I/R by deep hypothermic circulatory arrest followed by 3 or 24 h of reperfusion or sham, myocardial protein abundance in AGS (hibernating summer active) and rats (n = 4 to 5/group) was quantified by label-free proteomics (n = 4 to 5/group) and correlated with metabolic changes. Results Compared to rats, hibernating AGS displayed markedly reduced plasma levels of troponin I, myocardial apoptosis, and left ventricular contractile dysfunction. Of the 1,320 rat and 1,478 AGS proteins identified, 545 were differentially expressed between hibernating AGS and rat hearts (47% up-regulated and 53% down-regulated). Gene ontology analysis revealed down-regulation in hibernating AGS hearts of most proteins involved in mitochondrial energy transduction, including electron transport chain complexes, acetyl CoA biosynthesis, Krebs cycle, glycolysis, and ketogenesis. Conversely, fatty acid oxidation enzymes and sirtuin-3 were up-regulated in hibernating AGS, with preserved peroxisome proliferator–activated receptor-α activity and reduced tissue levels of acylcarnitines and ceramides after I/R. Conclusions Natural cardioprotective adaptations in hibernators involve extensive metabolic remodeling, featuring increased expression of fatty acid metabolic proteins and reduced levels of toxic lipid metabolites. Robust up-regulation of sirtuin-3 suggests that posttranslational modifications may underlie organ protection in hibernating mammals.
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Thatcher, Bradley J., and Kenneth B. Storey. "Glutamate dehydrogenase from liver of euthermic and hibernating Richardson's ground squirrels: Evidence for two distinct enzyme forms." Biochemistry and Cell Biology 79, no. 1 (January 1, 2001): 11–19. http://dx.doi.org/10.1139/o00-086.
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Glutamate dehydrogenase (GDH) was purified to homogeneity from the liver of euthermic (37°C body temperature) and hibernating (torpid, 5°C body temperature) Richardson's ground squirrels (Spermophilus richardsonii). SDS-PAGE yielded a subunit molecular weight of 59.5 ± 2 kDa for both enzymes, but reverse phase and size exclusion HPLC showed native molecular weights of 335 ± 5 kDa for euthermic and 320 ± 5 kDa for hibernator GDH. Euthermic and hibernator GDH differed substantially in apparent Km values for glutamate, NH4+, and α-ketoglutarate, as well as in Ka and IC50 values for nucleotide and ion activators and inhibitors. Kinetic properties of each enzyme were differentially affected by assay temperature (37 versus 5°C). For example, the Km for α-ketoglutarate of euthermic GDH was higher at 5°C (3.66 ± 0.34 mM) than at 37°C (0.10 ± 0.01 mM), whereas hibernator GDH had a higher affinity for α-ketoglutarate at 5°C (Km was 0.98 ± 0.08 mM at 37°C and 0.43 ± 0.02 mM at 5°C). Temperature effects on Ka ADP values of the enzymes followed a similar pattern; GTP inhibition was strongest with the euthermic enzyme at 37°C and weakest with hibernator GDH at 5°C. Entry into hibernation leads to stable changes in the properties of ground squirrel liver GDH that allow the enzyme to function optimally at the prevailing body temperature.Key words: mammalian hibernation, amino acid metabolism, temperature-dependent enzyme kinetics, Spermophilus richardsonii.
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Boyles, Justin G., Emily M. Johnson, Nathan W. Fuller, Kirk A. Silas, Lily Hou, Winifred F. Frick, and Liam P. McGuire. "Behavioural microclimate selection and physiological responses to environmental conditions in a hibernating bat." Canadian Journal of Zoology 100, no. 3 (March 2022): 233–38. http://dx.doi.org/10.1139/cjz-2021-0193.
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Hibernators adjust the expression of torpor behaviourally and physiologically to balance the benefits of energy conservation in hibernation against the physiological and ecological costs. Small fat-storing species, like many cave-hibernating bats, have long been thought to be highly constrained in their expression of hibernation because they must survive winter relying only on endogenous energy stores. We evaluated behavioural microclimate selection in tri-colored bats (Perimyotis subflavus (F. Cuvier, 1832)) across a 3-month hibernation experiment under laboratory conditions. We also opportunistically tested for evidence of acclimatization in torpid metabolic rate (TMR). When given access to gradients in microclimate, bats tended to choose the warmest temperature available (11 °C) while almost completely avoiding the driest condition available (85% relative humidity at 8 °C). Furthermore, bats held at different temperatures over the course of the hibernation showed no differences in TMR when measured under common conditions at the end of hibernation. Taken together, our results suggest that selective pressures to conserve energy during hibernation are not overwhelmingly strong and further support the proposition that optimal expression of hibernation is something less than the maximal expression of hibernation unless the animal is nearing starvation.
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Prendergast, Brian J., David A. Freeman, Irving Zucker, and Randy J. Nelson. "Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 282, no. 4 (April 1, 2002): R1054—R1062. http://dx.doi.org/10.1152/ajpregu.00562.2001.
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Golden-mantled ground squirrels ( Spermophilus lateralis) undergo seasonal hibernation during which core body temperature (Tb) values are maintained 1–2°C above ambient temperature. Hibernation is not continuous. Squirrels arouse at ∼7-day intervals, during which Tbincreases to 37°C for ∼16 h; thereafter, they return to hibernation and sustain low Tbs until the next arousal. Over the course of the hibernation season, arousals consume 60–80% of a squirrel's winter energy budget, but their functional significance is unknown and disputed. Host-defense mechanisms appear to be downregulated during the hibernation season and preclude normal immune responses. These experiments assessed immune function during hibernation and subsequent periodic arousals. The acute-phase response to bacterial lipopolysaccharide (LPS) was arrested during hibernation and fully restored on arousal to normothermia. LPS injection (ip) resulted in a 1–1.5°C fever in normothermic animals that was sustained for >8 h. LPS was without effect in hibernating squirrels, neither inducing fever nor provoking arousal, but a fever did develop several days later, when squirrels next aroused from hibernation; the duration of this arousal was increased sixfold above baseline values. Intracerebroventricular infusions of prostaglandin E2provoked arousal from hibernation and induced fever, suggesting that neural signaling pathways that mediate febrile responses are functional during hibernation. Periodic arousals may activate a dormant immune system, which can then combat pathogens that may have been introduced immediately before or during hibernation.
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Tsiouris, John A., Ved P. S. Chauhan, Ashfaq M. Sheikh, Abha Chauhan, Mazhar Malik, and Michael R. Vaughan. "Similarities in acute phase protein response during hibernation in black bears and major depression in humans: a response to underlying metabolic depression?" Canadian Journal of Zoology 82, no. 9 (September 1, 2004): 1468–76. http://dx.doi.org/10.1139/z04-122.
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This study investigated the effects of hibernation with mild hypothermia and the stress of captivity on levels of six acute-phase proteins (APPs) in serial samples of serum from 11 wild and 6 captive black bears (Ursus ameri canus Pallas, 1780) during active and hibernating states. We hypothesize that during hibernation with mild hypothermia, bears would show an APP response similar to that observed in major depression. Enzyme-linked immuno absorbent assay was used to measure alpha2-macroglobulin and C-reactive protein, and a nephelometer to measure alpha1-antitrypsin, hapto globin, ceruloplasmin, and transferrin. Levels of all other proteins except ceruloplasmin were significantly elevated during hibernation in both wild and captive bears at the p < 0.05 to p < 0.001 level. Alpha2-macroglobulin and C-reactive-protein levels were increased in captive versus wild bears in both active and hibernating states at the p < 0.01 to p < 0.0001 level. During hibernation with mild hypothermia, black bears do not show immunosuppression, but show an increased APP response similar to that in patients with major depression. This APP response is explained as an adaptive response to the underlying metabolic depression in both conditions. Metabolic depression in hibernating bears is suggested as a natural model for research to explain the neurobiology of depression.
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Pratihar, Suman, and Jayanta Kumar Kundu. "Metabolic changes during hibernating period in Indian common toad, Duttaphrynus melanostictus (Schneider, 1799)." Journal of Applied and Natural Science 1, no. 1 (June 1, 2009): 44–46. http://dx.doi.org/10.31018/jans.v1i1.32.
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The present investigation reports the effect of hibernation on different blood-plasma biochemical parameters viz. plasma protein, plasma glucose and blood urea, thyroid hormone and cholesterol in the Indian Common toad (Duttaphrynus melanostictus). The study indicated that the total plasma protein is decreased significantly in hibernating toads. The decline in thyroid hormone concentration had its behavioral and physiological response that leads to increase and sustain cholesterol level in serum. But plasma glucose was significantly decreased in hibernating toads. During the hibernating phase increased urea concentration in blood acts as cryoprotectant agent, which helps the hibernating animals to sustain in winter. Thus during hibernation these altered metabolic changes appear to be essential for survival.
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Carey, Hannah V., William A. Walters, and Rob Knight. "Seasonal restructuring of the ground squirrel gut microbiota over the annual hibernation cycle." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 304, no. 1 (January 1, 2013): R33—R42. http://dx.doi.org/10.1152/ajpregu.00387.2012.
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Many hibernating mammals suspend food intake during winter, relying solely on stored lipids to fuel metabolism. Winter fasting in these species eliminates a major source of degradable substrates to support growth of gut microbes, which may affect microbial community structure and host-microbial interactions. We explored the effect of the annual hibernation cycle on gut microbiotas using deep sequencing of 16S rRNA genes from ground squirrel cecal contents. Squirrel microbiotas were dominated by members of the phyla Bacteroidetes, Firmicutes, and Verrucomicrobia. UniFrac analysis showed that microbiotas clustered strongly by season, and maternal influences, diet history, host age, and host body temperature had minimal effects. Phylogenetic diversity and numbers of operational taxonomic units were lowest in late winter and highest in the spring after a 2-wk period of refeeding. Hibernation increased relative abundance of Bacteroidetes and Verrucomicrobia, phyla that contain species capable of surviving on host-derived substrates such as mucins, and reduced relative abundance of Firmicutes, many of which prefer dietary polysaccharides. Hibernation reduced cecal short-chain fatty acid and ammonia concentrations, and increased and decreased concentrations of acetate and butyrate, respectively. These results indicate that the ground squirrel microbiota is restructured each year in a manner that reflects differences in microbial preferences for dietary vs. host-derived substrates, and thus the competitive abilities of different taxa to survive in the altered environment in the hibernator gut.
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Ohtsuki, Toshiho, Howard Jaffe, Michael Brenner, Nabil Azzam, Rita Azzam, Kai U. Frerichs, and John M. Hallenbeck. "Stimulation of Tyrosine Phosphorylation of a Brain Protein by Hibernation." Journal of Cerebral Blood Flow & Metabolism 18, no. 9 (September 1998): 1040–45. http://dx.doi.org/10.1097/00004647-199809000-00014.
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Mammalian hibernation is a state of natural tolerance to severely decreased brain blood flow. As protein tyrosine phosphorylation is believed to be involved in the development of resistance to potentially cell-damaging insults, we used immunoblotting for the phosphotyrosine moiety to analyze extracts from various tissues of hibernating and nonhibernating ground squirrels. A single, hibernation-specific phosphoprotein was detected in the brain, but not in any other tissue tested. This protein, designated pp98 to reflect its apparent molecular weight, is distributed throughout the brain, and is associated with the cellular membrane fraction. The presence of the protein is tightly linked to the hibernation state; it is not present in contemporaneously assayed animals that are exposed to the same cold temperature as the hibernators, is present for the duration of a hibernation bout (tested from 1 to 14 days), and disappears within 1 hour of arousal from hibernation. The close association of pp98 with the hibernation state, its presence in cellular membranes, and the known properties of membrane phosphotyrosine proteins suggest that it may transduce a signal for adaptation to the limited availability of oxygen and glucose and low cellular temperature that characterizes hibernation in the ground squirrel.
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Carey, Hannah V., and Sandra L. Martin. "Preservation of intestinal gene expression during hibernation." American Journal of Physiology-Gastrointestinal and Liver Physiology 271, no. 5 (November 1, 1996): G805—G813. http://dx.doi.org/10.1152/ajpgi.1996.271.5.g805.
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The role of luminal nutrients in regulating enterocyte gene expression was studied in a natural model for long-term fasting, the hibernating ground squirrel. Squirrels were studied during the active season and during the hibernation season when they had not eaten for at least 12 wk. The specific activities of sucrase, isomaltase, and intestinal alkaline phosphatase in jejunal brush-border membranes were similar in hibernating and active squirrels, whereas amino-oligopeptidase was reduced in hibernators. Na+-K+-adenosinetriphosphatase activity in jejunal mucosa was unchanged by hibernation. Densitometric analysis of Western blots showed that abundance of sucrase-isomaltase (SI), amino-oligopeptidase, and the Na+-glucose cotransporter SGLT1 was similar in the two activity states. Preservation of SI abundance in hibernation was confirmed by immunocytochemistry. Slot-blot analysis revealed no differences in mRNAlevels for these proteins between hibernating and active squirrels. Enterocyte proliferation and migration rates were greatly suppressed in torpid squirrels but increased immediately upon rewarming during arousals. These results demonstrate the striking constancy of enterocyte gene expression despite long-term fasting in a hibernating mammal. small intestine; brush-border proteins; enzymes; sodium-glucose cotransporter Submitted on November 15, 1995 Accepted on April 24, 1996
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Storey, Kenneth B. "Investigations of the mechanisms of glycolytic control during hibernation." Canadian Journal of Zoology 65, no. 12 (December 1, 1987): 3079–83. http://dx.doi.org/10.1139/z87-467.
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Molecular mechanisms of glycolytic rate control during hibernation were investigated in the meadow jumping mouse, Zapus hudsonius. The content of fructose-2, 6-bisphosphate, a potent activator of phosphofructokinase, decreased significantly in brain, heart, and fat pad after 5–8 days of hibernation, rose in kidney, and was unchanged in skeletal muscle. Apparent covalent modification of regulatory enzymes of glycolysis during hibernation was examined in brain, heart, kidney, and skeletal muscle but occurred only in selected instances. Hibernation led to a significant reduction in the percentage of glycogen phosphorylase in the phosphorylated a form in brain and produced kinetic changes (altered Ka AMP, I50 citrate) in phosphofructokinase from heart indicative of enzyme covalent modification. No evidence for covalent modification of pyruvate kinase during hibernation was found in any tissue. Covalent modification of enzymes and alterations in fructose-2, 6-bisphosphate content offer organ-specific control over glycolytic rate during hibernation in response to both the general metabolic rate depression of the hibernating state and the individual adjustments in organ fuel use.
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Revsbech, Inge G., Hans Malte, Ole Fröbert, Alina Evans, Stéphane Blanc, Johan Josefsson, and Angela Fago. "Decrease in the red cell cofactor 2,3-diphosphoglycerate increases hemoglobin oxygen affinity in the hibernating brown bear Ursus arctos." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 304, no. 1 (January 1, 2013): R43—R49. http://dx.doi.org/10.1152/ajpregu.00440.2012.
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During winter hibernation, brown bears ( Ursus arctos) reduce basal O2 consumption rate to ∼25% compared with the active state, while body temperature decreases moderately (to ∼30°C), suggesting a temperature-independent component in their metabolic depression. To establish whether changes in O2 consumption during hibernation correlate with changes in blood O2 affinity, we took blood samples from the same six individuals of hibernating and nonhibernating free-ranging brown bears during winter and summer, respectively. A single hemoglobin (Hb) component was detected in all samples, indicating no switch in Hb synthesis. O2 binding curves measured on red blood cell lysates at 30°C and 37°C showed a less temperature-sensitive O2 affinity than in other vertebrates. Furthermore, hemolysates from hibernating bears consistently showed lower cooperativity and higher O2 affinity than their summer counterparts, regardless of the temperature. We found that this increase in O2 affinity was associated with a significant decrease in the red cell Hb-cofactor 2,3-diphosphoglycerate (DPG) during hibernation to approximately half of the summer value. Experiments performed on purified Hb, to which DPG had been added to match summer and winter levels, confirmed that the low DPG content was the cause of the left shift in the Hb-O2 equilibrium curve during hibernation. Levels of plasma lactate indicated that glycolysis is not upregulated during hibernation and that metabolism is essentially aerobic. Calculations show that the increase in Hb-O2 affinity and decrease in cooperativity resulting from decreased red cell DPG may be crucial in maintaining a fairly constant tissue oxygen tension during hibernation in vivo.
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Mulawa, Emily A., Jay S. Kirkwood, Lisa M. Wolfe, Samantha J. Wojda, Jessica E. Prenni, Gregory L. Florant, and Seth W. Donahue. "Seasonal Changes in Endocannabinoid Concentrations between Active and Hibernating Marmots (Marmota flaviventris)." Journal of Biological Rhythms 33, no. 4 (June 4, 2018): 388–401. http://dx.doi.org/10.1177/0748730418777660.
Full textAbstract:
Hibernation is a naturally occurring model for studying diseases such as obesity and osteoporosis. Hibernators, marmots (Marmota flaviventris) among them, are able to nearly double their body mass by increasing fat stores prior to hibernation without the negative consequences of obesity. They are also physically inactive for extended periods of time without experiencing negative effects on the skeleton. The endocannabinoid system is involved in modulating neural signaling, circannual rhythms, behavior, appetite, thermogenesis, and bone and energy metabolism. These systems are also altered to maintain homeostasis during hibernation. This study aims to better understand the involvement of the endocannabinoid system in the regulation of physiological processes during hibernation by quantifying the seasonal variation of endocannabinoids and endocannabinoid-like ligands in both active and hibernating marmots. We hypothesized that there would be significant changes in endocannabinoid concentrations at the tissue level in marmots between active and hibernating states. Concentrations were measured in brain, serum, brown adipose tissue, white adipose tissue, bone marrow, cortical bone, and trabecular bone using microflow chromatography coupled with tandem quadrupole mass spectrometry. Significant changes were found, such as a 30-fold decrease in 2-arachidonoyl glycerol (2-AG) in cortical bone during hibernation. Many endocannabinoid and endocannabinoid-like ligands decreased in brown adipose tissue, white adipose tissue, and cortical bone, while several ligands increased in bone marrow. This result supports our hypothesis and suggests the possibility of a peripherally controlled shift in energy metabolism, reduction in bone metabolism, and suppression of the immune system during hibernation.
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Fleck, Courtney C., and Hannah V. Carey. "Modulation of apoptotic pathways in intestinal mucosa during hibernation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 289, no. 2 (August 2005): R586—R595. http://dx.doi.org/10.1152/ajpregu.00100.2005.
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Mammalian hibernation is associated with several events that can affect programmed cell death (apoptosis) in nonhibernators, including marked changes in blood flow, extended fasting, and oxidative stress. However, the effect of hibernation on apoptosis is poorly understood. Here, we investigated apoptosis and expression of proteins involved in apoptotic pathways in intestinal mucosa of summer and hibernating ground squirrels. We used terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) to identify possible apoptotic enterocytes in small intestine of summer squirrels and hibernating squirrels throughout the winter. Nuclear TUNEL staining increased as hibernation progressed, but the staining pattern was diffuse and not accompanied by chromatin condensation or apoptotic bodies. Electrophoresis of mucosal DNA revealed no ladders typical of apoptosis. Nuclear levels of proapoptotic p53 protein were fourfold less in hibernators compared with summer squirrels. A 12-fold increase in anti-apoptotic Bcl-xL compared with a 2-fold increase in proapoptotic Bax suggested a balance in favor of antiapoptotic signaling in hibernators. There was no change in Bcl-2 protein expression but phospho-Bcl-2 increased in mucosa of hibernators. Hibernation had minimal effects on expression of active caspase-8 or -9, whereas caspase-3-specific activity was lower in hibernators during an interbout arousal compared with summer squirrels. Expression of the prosurvival protein Akt increased 20-fold during hibernation, but phospho-Akt was not altered. These data provide evidence for enhanced expression of antiapoptotic proteins during hibernation that may promote enterocyte survival in a pro-oxidative, proapoptotic environment.
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El Kebbaj, Zakaria, Pierre Andreoletti, Driss Mountassif, Mostafa Kabine, Hervé Schohn, Michel Dauça, Norbert Latruffe, M'Hammed Saïd El Kebbaj, and Mustapha Cherkaoui-Malki. "Differential Regulation of Peroxisome Proliferator-Activated Receptor (PPAR)-α1 and Truncated PPARα2 as an Adaptive Response to Fasting in the Control of Hepatic Peroxisomal Fatty Acid β-Oxidation in the Hibernating Mammal." Endocrinology 150, no. 3 (October 23, 2008): 1192–201. http://dx.doi.org/10.1210/en.2008-1394.
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Seasonal obesity and fasting-associated hibernation are the two major metabolic events governing hepatic lipid metabolism in hibernating mammals. In this process, however, the role of the nuclear receptor known as peroxisome proliferator-activated receptor (PPAR)-α has not been elucidated yet. Here we show, as in human, that jerboa (Jaculus orientalis) liver expresses both active wild-type PPARα (PPARα1wt) and truncated PPARα forms and that the PPARα1wt to truncated PPARα2 ratio, which indicates the availability of active PPARα1wt, is differentially regulated during fasting-associated hibernation. Functional activation of hepatic jerboa PPARα, during prehibernating and hibernating states, was demonstrated by the induction of its target genes, which encode peroxisomal proteins such as acyl-CoA oxidase 1, peroxisomal membrane protein 70, and catalase, accompanied by a concomitant induction of PPARα thermogenic coactivator PPARγ coactivator-1α. Interestingly, sustained activation of PPARα by its hypolipidemic ligand, ciprofibrate, abrogates the adaptive fasting response of PPARα during prehibernation and overinduces its target genes, disrupting the prehibernation fattening process. In striking contrast, during fasting-associated hibernation, jerboas exhibit preferential up-regulation of hepatic peroxisomal fatty acid oxidation instead of the mitochondrial pathway, which is down-regulated. Taken together, our results strongly suggest that PPARα is subject to a hibernation-dependent splicing regulation in response to feeding-fasting conditions, which defines the activity of PPARα and the activation of its target genes during hibernation bouts of jerboas. Jerboa PPARα is subject to a hibernation-dependent splicing regulation in response to feeding-fasting conditions, which define activation of PPARα and its target genes.
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Staples, James F., and Peter W. Hochachka. "Liver energy metabolism during hibernation in the golden-mantled ground squirrel, Spermophilus lateralis." Canadian Journal of Zoology 75, no. 7 (July 1, 1997): 1059–65. http://dx.doi.org/10.1139/z97-127.
Full textAbstract:
Large changes in ATP production capacities and rates have been reported in mammalian hibernators throughout the different stages of the hibernation cycle. In this study we showed that total extractable liver [ATP], [ADP], and [ATP]/[ADP] do not differ among summer normothermic, hibernating, and aroused golden-mantled ground squirrels, Spermophilus lateralis, indicating that metabolism remains well balanced throughout the hibernation cycle. This implies that rates of ATP consumption must be down-regulated during deep hibernation in order to maintain this balance. Despite this, basal oxygen-consumption rates [Formula: see text] of hepatocytes isolated from hibernating, aroused, and summer cold-acclimated ground squirrels were 22.4–35.1% higher than those from ground squirrels in the summer normothermic condition when measured at 37 °C. The relatively high hepatocyte [Formula: see text] may help to minimize interbout arousal times, reducing energy demands during the hibernation season. At 7 °C, hepatocyte [Formula: see text] values do not differ among the four groups; however, the Q10 for hepatocyte [Formula: see text] is significantly lower for the summer group, suggesting lower temperature sensitivity. Despite the seasonal changes in thyroid hormone status known to occur in scuirid hibernators, the proportion of hepatocyte [Formula: see text] attributed to Na+,K+-ATPase, estimated by inhibition with 1 mM ouabain, is only around 15% and does not differ among hibernation/seasonal conditions.
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Malatesta, Manuela, Manuela Costanzo, Barbara Cisterna, and Carlo Zancanaro. "Satellite Cells in Skeletal Muscle of the Hibernating Dormouse, a Natural Model of Quiescence and Re-Activation: Focus on the Cell Nucleus." Cells 9, no. 4 (April 23, 2020): 1050. http://dx.doi.org/10.3390/cells9041050.
Full textAbstract:
Satellite cells (SCs) participate in skeletal muscle plasticity/regeneration. Activation of SCs implies that nuclear changes underpin a new functional status. In hibernating mammals, periods of reduced metabolic activity alternate with arousals and resumption of bodily functions, thereby leading to repeated cell deactivation and reactivation. In hibernation, muscle fibers are preserved despite long periods of immobilization. The structural and functional characteristics of SC nuclei during hibernation have not been investigated yet. Using ultrastructural and immunocytochemical analysis, we found that the SCs of the hibernating edible dormouse, Glis glis, did not show apoptosis or necrosis. Moreover, their nuclei were typical of quiescent cells, showing similar amounts and distributions of heterochromatin, pre-mRNA transcription and processing factors, as well as paired box protein 7 (Pax7) and the myogenic differentiation transcription factor D (MyoD), as in euthermia. However, the finding of accumulated perichromatin granules (i.e., sites of storage/transport of spliced pre-mRNA) in SC nuclei of hibernating dormice suggested slowing down of the nucleus-to-cytoplasm transport. We conclude that during hibernation, SC nuclei maintain similar transcription and splicing activity as in euthermia, indicating an unmodified status during immobilization and hypometabolism. Skeletal muscle preservation during hibernation is presumably not due to SC activation, but rather to the maintenance of some functional activity in myofibers that is able to counteract muscle wasting.
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Herinckx, Gaëtan, Nusrat Hussain, Fred R. Opperdoes, Kenneth B. Storey, Mark H. Rider, and Didier Vertommen. "Changes in the phosphoproteome of brown adipose tissue during hibernation in the ground squirrel, Ictidomys tridecemlineatus." Physiological Genomics 49, no. 9 (September 1, 2017): 462–72. http://dx.doi.org/10.1152/physiolgenomics.00038.2017.
Full textAbstract:
Mammalian hibernation is characterized by metabolic rate depression and a strong decrease in core body temperature that together create energy savings such that most species do not have to eat over the winter months. Brown adipose tissue (BAT), a thermogenic tissue that uses uncoupled mitochondrial respiration to generate heat instead of ATP, plays a major role in rewarming from deep torpor. In the present study we developed a label-free liquid chromatography mass spectrometry (LC-MS) strategy to investigate both differential protein expression and protein phosphorylation in BAT extracts from euthermic vs. hibernating ground squirrels ( Ictidomys tridecemlineatus). In particular, we incorporated the filter-assisted sample preparation protocol, which provides a more in-depth analysis compared with gel-based and other LC-MS proteomics approaches. Surprisingly, mitochondrial membrane and matrix protein expression in BAT was largely constant between active euthermic squirrels and their hibernating counterparts. Validation by immunoblotting confirmed that the protein levels of mitochondrial respiratory chain complexes were largely unchanged in hibernating vs. euthermic animals. On the other hand, phosphoproteomics revealed that pyruvate dehydrogenase (PDH) phosphorylation increased during squirrel hibernation, confirmed by immunoblotting with phospho-specific antibodies. PDH phosphorylation leads to its inactivation, which suggests that BAT carbohydrate oxidation is inhibited during hibernation. Phosphorylation of hormone-sensitive lipase (HSL) was also found to increase during hibernation, suggesting that HSL would be active in BAT to produce the fatty acids that are likely the primary fuel for thermogenesis upon arousal. Increased perilipin phosphorylation along with that of a number of other proteins was also revealed, emphasizing the importance of protein phosphorylation as a regulatory mechanism during mammalian hibernation.
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Xie, Zhigang, Ibrahim M. Ahmad, Lirong Zuo, Hui Wang, and Dongming Li. "Hibernation with Rhythmicity in the Retina, Brain, and Plasma but Not in the Liver of Hibernating Giant Spiny Frogs (Quasipaa spinosa)." Biology 11, no. 5 (May 9, 2022): 722. http://dx.doi.org/10.3390/biology11050722.
Full textAbstract:
Hibernation in ectotherms is well known, however, it is unclear how the circadian clock regulates endocrine and antioxidative defense systems of aquatic hibernators. Using the giant spiny frog (Quasipaa spinosa), we studied mRNA expression levels of (1) circadian core clock (Bmal1, Clock, Cry1 and Per2), clock-controlled (Ror-α, Mel-1c and AANAT), and antioxidant enzyme (AOE) (SOD1, SOD2, CAT and GPx) genes in retina, brain, and liver; and (2) plasma melatonin (MT) and corticosterone (CORT) levels, over a 24-hour period at six intervals pre-hibernation and during hibernation. Our results showed that brain Bmal1, Cry1, Per2 and Mel-1c were rhythmic pre-hibernation and Clock and Ror-α during hibernation. However, the retina Bmal1, Clock and Mel-1c, and plasma MT became rhythmic during hibernation. All brain AOEs (SOD1, SOD2, CAT and GPx) were rhythmic pre-hibernation and became non-rhythmic but upregulated, except SOD1, during hibernation. However, plasma CORT and liver clocks and AOEs were non-rhythmic in both periods. The mRNA expression levels of AOEs closely resembled those of Ror-α but not plasma MT oscillations. In the hibernating aquatic frogs, these modulations of melatonin, as well as clock and clock-controlled genes and AOEs might be fundamental for them to remain relatively inactive, increase tolerance, and escape hypoxia, and to prepare for arousal.
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Lilley, T. M., J. M. Prokkola, J. S. Johnson, E. J. Rogers, S. Gronsky, A. Kurta, D. M. Reeder, and K. A. Field. "Immune responses in hibernating little brown myotis ( Myotis lucifugus ) with white-nose syndrome." Proceedings of the Royal Society B: Biological Sciences 284, no. 1848 (February 8, 2017): 20162232. http://dx.doi.org/10.1098/rspb.2016.2232.
Full textAbstract:
White-nose syndrome (WNS) is a fungal disease responsible for decimating many bat populations in North America. Pseudogymnoascus destructans ( Pd ), the psychrophilic fungus responsible for WNS, prospers in the winter habitat of many hibernating bat species. The immune response that Pd elicits in bats is not yet fully understood; antibodies are produced in response to infection by Pd , but they may not be protective and indeed may be harmful. To understand how bats respond to infection during hibernation, we studied the effect of Pd inoculation on the survival and gene expression of captive hibernating Myotis lucifugus with varying pre-hibernation antifungal antibody titres. We investigated gene expression through the transcription of selected cytokine genes ( Il6 , Il17a , Il1b , Il4 and Ifng ) associated with inflammatory, Th1, Th2 and Th17 immune responses in wing tissue and lymph nodes. We found no difference in survival between bats with low and high anti- Pd titres, although anti- Pd antibody production during hibernation differed significantly between infected and uninfected bats. Transcription of Il6 and Il17a was higher in the lymph nodes of infected bats compared with uninfected bats. Increased transcription of these cytokines in the lymph node suggests that a pro-inflammatory immune response to WNS is not restricted to infected tissues and occurs during hibernation. The resulting Th17 response may be protective in euthermic bats, but because it may disrupt torpor, it could be detrimental during hibernation.
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Jani, Alkesh, Sandra L. Martin, Swati Jain, Daniel Keys, and Charles L. Edelstein. "Renal adaptation during hibernation." American Journal of Physiology-Renal Physiology 305, no. 11 (December 1, 2013): F1521—F1532. http://dx.doi.org/10.1152/ajprenal.00675.2012.
Full textAbstract:
Hibernators periodically undergo profound physiological changes including dramatic reductions in metabolic, heart, and respiratory rates and core body temperature. This review discusses the effect of hypoperfusion and hypothermia observed during hibernation on glomerular filtration and renal plasma flow, as well as specific adaptations in renal architecture, vasculature, the renin-angiotensin system, and upregulation of possible protective mechanisms during the extreme conditions endured by hibernating mammals. Understanding the mechanisms of protection against organ injury during hibernation may provide insights into potential therapies for organ injury during cold storage and reimplantation during transplantation.
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Onyeka, J. O. A., and P. F. L. Boreham. "Population studies, physiological state and mortality factors of overwintering adult populations of females of Culex pipiens L. (Diptera: Culicidae)." Bulletin of Entomological Research 77, no. 1 (March 1987): 99–111. http://dx.doi.org/10.1017/s0007485300011585.
Full textAbstract:
AbstractThe biology of overwintering populations of adults of Culex pipiens L. was studied between October 1977 and April 1980 in southern England. Data obtained from population studies showed that there was a rapid build-up at the beginning of hibernation in August, reaching a peak in late October-early November each year and gradually decreasing from December. Extensive movement both in and out and within the hibernation site occurred, with many individuals changing their locations or hibernacula during the course of hibernation. Studies on induced feeding showed that in the early months of hibernation (August-October) exposure to constant light for a minimum period of 12 days was required before the females would take a blood-meal. This period decreased during the course of hibernation. Observations on the physiological condition of hibernating females revealed that up to 90% of the population were inseminated. A few parous females entered hibernation shelters at the onset of winter but did not survive the winter. Furthermore, females used up about 80% of their fat food reserves during hibernation, while there was little or no change in the quantity of glycogen present. From an assessment of the impact of mortality factors on a population of known size, it was observed that exodus from the hibernation shelters accounted for about 30% reduction in the population size while depletion of food reserves and predation by spiders accounted for approximately 15 and 20% mortality, respectively.
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Kilduff, T. S., F. R. Sharp, and H. C. Heller. "Progressive activation of paratrigeminal nucleus during entrance to hibernation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 255, no. 1 (July 1, 1988): R178—R181. http://dx.doi.org/10.1152/ajpregu.1988.255.1.r178.
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The paratrigeminal nucleus (Pa5) undergoes a progressive increase in its uptake of 2-[14C]deoxyglucose (2DG) relative to other brain structures during entrance to hibernation in the ground squirrel. This highly significant increase results in the Pa5 becoming the most highly labeled brain region during hibernation, even though it exhibits one of the lowest levels of 2DG uptake in the brain during the nonhibernating state. The progressive activation of the Pa5 observed during entrance is reversed during arousal from hibernation. These observations and the neuroanatomical projections of the Pa5 implicate this nucleus as playing a role in the entrance and maintenance of the hibernating state.
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Boyer, Bert B., Brian M. Barnes, Bradford B. Lowell, and Danica Grujic. "Differential regulation of uncoupling protein gene homologues in multiple tissues of hibernating ground squirrels." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 275, no. 4 (October 1, 1998): R1232—R1238. http://dx.doi.org/10.1152/ajpregu.1998.275.4.r1232.
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Nonshivering thermogenesis in brown adipose tissue (BAT) provides heat through activation of a mitochondrial uncoupling protein (UCP1), which causes futile electron transport cycles without the production of ATP. Recent discovery of two molecular homologues, UCP2, expressed in multiple tissues, and UCP3, expressed in muscle, has resulted in investigation of their roles in thermoregulatory physiology and energy balance. To determine the expression pattern of Ucp homologues in hibernating mammals, we compared relative mRNA levels of Ucp1, -2, and -3 in BAT, white adipose tissue (WAT), and skeletal muscle of arctic ground squirrels ( Spermophilus parryii) hibernating at different ambient and body temperatures, with levels determined in tissues from ground squirrels not in hibernation. Here we report significant increases in mRNA levels for Ucp2 in WAT (1.6-fold) and Ucp3 in skeletal muscle (3-fold) during hibernation. These results indicate the potential for a role of UCP2 and UCP3 in thermal homeostasis during hibernation and indicate that parallel mechanisms and multiple tissues could be important for nonshivering thermoregulation in mammals.
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Frerichs, Kai U., Charles Kennedy, Louis Sokoloff, and John M. Hallenbeck. "Local Cerebral Blood Flow during Hibernation, a Model of Natural Tolerance to “Cerebral Ischemia”." Journal of Cerebral Blood Flow & Metabolism 14, no. 2 (March 1994): 193–205. http://dx.doi.org/10.1038/jcbfm.1994.26.
Full textAbstract:
The breakdown of cellular homeostasis and progressive neuronal destruction in cerebral ischemia appears to be mediated by a complex network of causes that are intricately interrelated. We have investigated a physiological state existing normally in nature in which mammals appear to tolerate the ordinarily detrimental effects of ischemia with reduced oxygen availability and to resist activation of self-destructive processes, i.e., mammalian hibernation. Ground squirrels (Spermophilus tridecemlineatus) were chronically implanted with arterial and venous catheters and telemetry devices for electroencephalography, electrocardiography, and monitoring of body temperature. The animals were placed in an environmental chamber at an ambient temperature of 5°C. Entrance into hibernation was characterized by a drop in heart rate followed by a gradual decline in body temperature and an isoelectric electroencephalogram. Cold-adapted active animals that were not hibernating served as controls. Cerebral blood flow (CBF) was measured in both groups with the autoradiographic [14C]iodoantipyrine method. Mean (±SD) mass-weighted CBF in the brain as a whole was 62 ± 16 ml/100 g/min (n = 4) in the control group but was reduced to ischemic levels, 7 ± 4 ml/100 g/min (n = 4), in the hibernating animals (p < 0.001). No neuropathological changes were found in similarly hibernating animals aroused from hibernation. Hibernation appears to be actively regulated, and hormonal factors may be involved. The identification and characterization of such factors and of the mechanisms used by hibernating species to increase ischemic tolerance and to blunt the destructive effects of ischemia may enable us to prevent or minimize the loss of homeostatic control during and after cerebral ischemia in other species.
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HEUSCH, GERD. "Hibernating Myocardium." Physiological Reviews 78, no. 4 (October 1, 1998): 1055–85. http://dx.doi.org/10.1152/physrev.1998.78.4.1055.
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Heusch, Gerd. Hibernating Myocardium. Physiol. Rev. 78: 1055–1085, 1998. — Decreased myocardial contraction occurs as a consequence of a reduction in blood flow. The concept of hibernation implies a downregulation of contractile function as an adaptation to a reduction in myocardial blood flow that serves to maintain myocardial integrity and viability during persistent ischemia. Unequivocal evidence for this concept exists in scenarios of myocardial ischemia that lasts for several hours, and sustained perfusion-contraction matching, recovery of energy and substrate metabolism, the potential for recruitment of inotropic reserve at the expense of metabolic recovery, and lack of necrosis are established criteria of short-term hibernation. The mechanisms of short-term hibernation, apart from reduced calcium responsiveness, are not clear at present. Experimental studies with chronic coronary stenosis lasting more than several hours have failed to continuously monitor flow and function. Nevertheless, a number of studies in chronic animal models and patients have demonstrated regional myocardial dysfunction at reduced resting blood flow that recovered upon reperfusion, consistent with chronic hibernation. Further studies are required to distinguish chronic hibernation from cumulative stunning. With a better understanding of the mechanisms underlying short-term hibernation, it is hoped that these adaptive responses can be recruited and reinforced to minimize the consequences of acute myocardial ischemia and delay impending infarction. Patients with chronic hibernation must be identified and undergo adequate reperfusion therapy.
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Horwitz, B. A., J. S. Hamilton, and K. S. Kott. "GDP binding to hamster brown fat mitochondria is reduced during hibernation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 249, no. 6 (December 1, 1985): R689—R693. http://dx.doi.org/10.1152/ajpregu.1985.249.6.r689.
Full textAbstract:
Preparation for hibernation is accompanied by increased thermogenic capacity of brown fat (BAT), an important site of thermogenesis during arousal from hibernation. This study examined whether that thermogenic capacity is reduced in hibernation and reactivated during arousal. In one set of experiments, Syrian hamsters were exposed to short photoperiod (10:14 light-dark) and cold (7 degrees C). Those not hibernating at death (n = 10) served as controls for those that were (n = 9). A third group (n = 10) was killed 80–90 min after arousal was initiated by manual perturbation. Mitochondrial GDP binding (nmol/mg mitochondrial protein) was used to estimate thermogenic capacity. In a second experimental series, BAT citrate (si)-synthase and 3-hydroxyacyl-CoA dehydrogenase activities were measured in hibernating and nonhibernating hamsters. Although there were no differences in the maximum activities of these enzymes, GDP binding was markedly lower in the hibernators relative to the nonhibernators (0.214 +/- 0.031 vs. 0.535 +/- 0.039). However, in the partially aroused hamsters, GDP binding had doubled (0.438 +/- 0.04). Thus hibernation is accompanied by a substantial reduction of BAT thermogenic capacity (as manifested by GDP binding), which is reversed during arousal. The rapidity of this reversal indicates that it does not involve the synthesis of new GDP binding sites.
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Popov, Igor V., Iraida S. Berezinskaia, Ilia V. Popov, Irina B. Martiusheva, Elizaveta V. Tkacheva, Vladislav E. Gorobets, Iuliia A. Tikhmeneva, et al. "Cultivable Gut Microbiota in Synanthropic Bats: Shifts of Its Composition and Diversity Associated with Hibernation." Animals 13, no. 23 (November 26, 2023): 3658. http://dx.doi.org/10.3390/ani13233658.
Full textAbstract:
The role of bats in the global microbial ecology no doubt is significant due to their unique immune responses, ability to fly, and long lifespan, all contributing to pathogen spread. Some of these animals hibernate during winter, which results in the altering of their physiology. However, gut microbiota shifts during hibernation is little studied. In this research, we studied cultivable gut microbiota composition and diversity of Nyctalus noctula before, during, and after hibernation in a bat rehabilitation center. Gut microorganisms were isolated on a broad spectrum of culture media, counted, and identified with mass spectrometry. Linear modeling was used to investigate associations between microorganism abundance and N. noctula physiological status, and alpha- and beta-diversity indexes were used to explore diversity changes. As a result, most notable changes were observed in Serratia liquefaciens, Hafnia alvei, Staphylococcus sciuri, and Staphylococcus xylosus, which were significantly more highly abundant in hibernating bats, while Citrobacter freundii, Klebsiella oxytoca, Providencia rettgeri, Citrobacter braakii, and Pedicoccus pentosaceus were more abundant in active bats before hibernation. The alpha-diversity was the lowest in hibernating bats, while the beta-diversity differed significantly among all studied periods. Overall, this study shows that hibernation contributes to changes in bat cultivable gut microbiota composition and diversity.