Seasonal patterns in the physiology of the European brown bear (Ursus arctos arctos) in Finland

Hissa, R.; Siekkinen, Juha; Hohtola, Esa; Saarela, Seppo; Hakala, Antero; Pudas, Jorma

doi:10.1016/0300-9629(94)90222-4

Cited by 130 publications

(132 citation statements)

References 24 publications

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“…Hissa (1997) also noted similar values in captive bears with significantly higher creatinine concentration during winter season comparing to summer. The study by Stenvinkel et al (2013a) on free-ranging brown bears in Sweden captured in summer and in winter, showed the significant differences between mean values in many biochemical parameters, with creatinine significantly increased in winter.…”

Section: Resultssupporting

confidence: 70%

“…Sleep/rest was the dominant behavior both outdoors and indoors. The obvious indicator of lower activity was body temperature (mean 35.9 o C) comparing to brown bears in the stage of full activity (37-37.5 o C, Hissa et al 1994). The temperature of hibernating free-ranging brown bears immobilized for research ranged from 32.2 to 34.8 o C within 35 minutes after inducing anesthesia (Evans et al 2012).…”

Section: Resultsmentioning

confidence: 99%

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Winter blood values of selected parameters in a group of non-hibernating captive brown bears (Ursus arctos)

Sergiel¹,

Bednarski²,

Maślak³

et al. 2015

Polish Journal of Veterinary Sciences

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Bears undergo some significant changes reflected in blood values during winter season. The most significant are reduced urea and increased creatinine, by some authors considered to be physiological indicators of hibernation. Studied group of six captive brown bears (Ursus arctos) showed decreased activity in winter but were accepting food and walked outdoors. Blood parameters assessed in February 2011 revealed mean values of leucocytes and neutrophils as significantly lower, and creatinine significantly increased compared to captive and free living bears sampled during other seasons when bears are active.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Winter blood values of selected parameters in a group of non-hibernating captive brown bears (Ursus arctos)

Sergiel¹,

Bednarski²,

Maślak³

et al. 2015

Polish Journal of Veterinary Sciences

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“…While skeletal muscle mass in ground squirrels and bats is reduced by 14 -65% during hibernation (7), no significant loss in lean body mass was observed in adult black bears during hibernation (25,29), except for 4 -10% reduction in muscle protein reported specifically for lactating females (38). Hibernating brown and black bears show a net increase in plasma protein concentration (17,27), and this is consistent with elevated protein synthesis in liver during hibernation. Lundberg et al (25) found that rates of whole body protein turnover, including protein anabolism and catabolism, were elevated three-to fivefold in hibernating black bears compared with summer active bears.…”

Section: Differential Gene Expression In Hibernating Black Bearsmentioning

confidence: 76%

“…This finding implies a reduction in urea production in hibernating black bears that is consistent with physiological and biochemical data. Significant decreases in the urea concentration in blood of hibernating bears are consistently ob- served (1,18,27) and attributed to both low production and active urea recycling through microbial ureolysis. Under the condition of no dietary intake of amino acids, reduced urea formation suggests redirection of amino acids from catabolic pathways followed by amino group utilization through the urea cycle to protein synthesis.…”

Section: Differential Gene Expression In Hibernating Black Bearsmentioning

confidence: 99%

“…Apart from reduced production and active recycling of urea, increases in protein catabolism in other tissues and organs may release additional amino acids to support elevated protein synthesis in liver and muscle. Biochemical data showed the increased degradation of the type I collagen in the connective tissues of hibernating bears (18) that may provide the essential amino acids for protein synthesis. The importance of regulation of proteolysis at protein level was recently demonstrated in skeletal muscle (11).…”

Section: Differential Gene Expression In Hibernating Black Bearsmentioning

confidence: 99%

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Elevated expression of protein biosynthesis genes in liver and muscle of hibernating black bears (Ursus americanus)

Fedorov

Goropashnaya

Tøien

et al. 2009

Physiological Genomics

125

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We conducted a large-scale gene expression screen using the 3,200 cDNA probe microarray developed specifically for Ursus americanus to detect expression differences in liver and skeletal muscle that occur during winter hibernation compared with animals sampled during summer. The expression of 12 genes, including RNA binding protein motif 3 (Rbm3), that are mostly involved in protein biosynthesis, was induced during hibernation in both liver and muscle. The Gene Ontology and Gene Set Enrichment analysis consistently showed a highly significant enrichment of the protein biosynthesis category by overexpressed genes in both liver and skeletal muscle during hibernation. Coordinated induction in transcriptional level of genes involved in protein biosynthesis is a distinctive feature of the transcriptome in hibernating black bears. This finding implies induction of translation and suggests an adaptive mechanism that contributes to a unique ability to reduce muscle atrophy over prolonged periods of immobility during hibernation. Comparing expression profiles in bears to small mammalian hibernators shows a general trend during hibernation of transcriptional changes that include induction of genes involved in lipid metabolism and carbohydrate synthesis as well as depression of genes involved in the urea cycle and detoxification function in liver. gene expression; hibernation; translation; RNA binding protein motif 3 MAMMALIAN HIBERNATION IS a physiological and behavioral adaptation involving a coordinated suppression of heat production and body temperature wherein whole body metabolism and energy demand are significantly reduced over several days to several months. During hibernation, heart and respiration rates, blood flow, and oxygen consumption decrease dramatically to Ͻ10% of normal or basal rates (2, 4). These physiological changes do not represent a loss of homeostasis but instead are precisely controlled and spontaneously reversible, and they allow individual animals to survive highly seasonal or unpredictable environments where food availability becomes lacking (7, 12). The molecular and genetic basis of hibernation in small mammals has only recently begun to be described, and little is known about its evolutionary history. Hibernating species have been found in diverse families among seven orders of mammals (26), however, and the interspersed phylogenetic distribution of hibernating and nonhibernating species has led to the hypothesis that rather than requiring the creation of novel gene products, hibernation results from the differential expression of genes that exist widely among mammals (35).Microarray technology provides powerful means for the unbiased detection of differences in expression of thousands of genes in a single hybridization experiment (14). In contrast to single-gene expression analysis, the genome-wide approach also allows for identification of coordinated transcriptional changes in functional groups of regulatory genes within metabolic and signaling pathways. Recent studies of differential gen...

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Integrative Physiology of Fasting

Secor

Carey

2016

Comprehensive Physiology

132

144

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Extended bouts of fasting are ingrained in the ecology of many organisms, characterizing aspects of reproduction, development, hibernation, estivation, migration, and infrequent feeding habits. The challenge of long fasting episodes is the need to maintain physiological homeostasis while relying solely on endogenous resources. To meet that challenge, animals utilize an integrated repertoire of behavioral, physiological, and biochemical responses that reduce metabolic rates, maintain tissue structure and function, and thus enhance survival. We have synthesized in this review the integrative physiological, morphological, and biochemical responses, and their stages, that characterize natural fasting bouts. Underlying the capacity to survive extended fasts are behaviors and mechanisms that reduce metabolic expenditure and shift the dependency to lipid utilization. Hormonal regulation and immune capacity are altered by fasting; hormones that trigger digestion, elevate metabolism, and support immune performance become depressed, whereas hormones that enhance the utilization of endogenous substrates are elevated. The negative energy budget that accompanies fasting leads to the loss of body mass as fat stores are depleted and tissues undergo atrophy (i.e., loss of mass). Absolute rates of body mass loss scale allometrically among vertebrates. Tissues and organs vary in the degree of atrophy and downregulation of function, depending on the degree to which they are used during the fast. Fasting affects the population dynamics and activities of the gut microbiota, an interplay that impacts the host's fasting biology. Fasting-induced gene expression programs underlie the broad spectrum of integrated physiological mechanisms responsible for an animal's ability to survive long episodes of natural fasting.

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Seasonal patterns in the physiology of the European brown bear (Ursus arctos arctos) in Finland

Cited by 130 publications

References 24 publications

Winter blood values of selected parameters in a group of non-hibernating captive brown bears (Ursus arctos)

Winter blood values of selected parameters in a group of non-hibernating captive brown bears (Ursus arctos)

Elevated expression of protein biosynthesis genes in liver and muscle of hibernating black bears (Ursus americanus)

Integrative Physiology of Fasting

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