scholarly journals Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)?

2021 ◽  
Author(s):  
Heiko T. Jansen ◽  
Brandon Evans Hutzenbiler ◽  
Hannah R. Hapner ◽  
Madeline L. McPhee ◽  
Anthony M. Carnahan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Insulin Sensitivity ◽  
Metabolic Rate ◽  
Ursus Arctos ◽  
Metabolic Effects ◽  
Energetic Cost ◽  
Grizzly Bears ◽  
Flux Analysis ◽  
Active Season ◽  
Ursus Arctos Horribilis

Hibernation is characterized by depression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) dextrose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (ß-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free-fatty acids and indices of metabolic rate, such as general activity, heart rate, and strength of the daily heart rate rhythm and insulin sensitivity were restored to roughly 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to the metabolic effects observed after glucose feeding, we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a roughly 33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared to fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial depression of circulating FFA with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further depression of metabolic function is likely to be an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.

scholarly journals Can offsetting the energetic cost of hibernation restore an active season phenotype in grizzly bears (Ursus arctos horribilis)?

2021 ◽  
Author(s):  
Heiko T. Jansen ◽  
Brandon Evans Hutzenbiler ◽  
Hannah R. Hapner ◽  
Madeline L. McPhee ◽  
Anthony M. Carnahan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Insulin Sensitivity ◽  
Metabolic Rate ◽  
Ursus Arctos ◽  
Metabolic Effects ◽  
Energetic Cost ◽  
Grizzly Bears ◽  
Flux Analysis ◽  
Active Season ◽  
Ursus Arctos Horribilis

ABSTRACTHibernation is characterized by suppression of many physiological processes. To determine if this state is reversible in a non-food caching species, we fed hibernating grizzly bears (Ursus arctos horribilis) glucose for 10 days to replace 53% or 100% of the estimated minimum daily energetic cost of hibernation. Feeding caused serum concentrations of glycerol and ketones (ß-hydroxybutyrate) to return to active season levels irrespective of the amount of glucose fed. By contrast, free-fatty acids and indices of metabolic rate, such as general activity, heart rate, and strength of the daily heart rate rhythm and insulin sensitivity were restored to roughly 50% of active season levels. Body temperature was unaffected by feeding. To determine the contribution of adipose to these metabolic effects of glucose feeding we cultured bear adipocytes collected at the beginning and end of the feeding and performed metabolic flux analysis. We found a roughly 33% increase in energy metabolism after feeding. Moreover, basal metabolism before feeding was 40% lower in hibernation cells compared to fed cells or active cells cultured at 37°C, thereby confirming the temperature independence of metabolic rate. The partial suppression of circulating FFA with feeding likely explains the incomplete restoration of insulin sensitivity and other metabolic parameters in hibernating bears. Further suppression of metabolic function is likely an active process. Together, the results provide a highly controlled model to examine the relationship between nutrient availability and metabolism on the hibernation phenotype in bears.

scholarly journals Systemic effects of a high saturated fat diet in grizzly bears (Ursus arctos horribilis)

2017 ◽  
Vol 95 (11) ◽  
pp. 797-807 ◽  
Author(s):  
D.R. Rivet ◽  
O.L. Nelson ◽  
C.A. Vella ◽  
H.T. Jansen ◽  
C.T. Robbins
Keyword(s):  
Fatty Acids ◽  
Ursus Arctos ◽  
Saturated Fatty Acids ◽  
Metabolic Effects ◽  
Food Sources ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Omega 3 ◽  
Necrosis Factor Alpha ◽  
Ursus Arctos Horribilis

Food sources for North America’s grizzly bear (Ursus arctos horribilis Ord, 1815) population have changed as habitats have fragmented, altering available resources and putting bears in contact with unnatural foods. Bears have evolved mechanisms to tolerate obesity, and do not develop adverse health consequences despite storing massive amounts of body fat. Captive adult grizzly bears were used to determine the effects of dietary fat on health. Group 1 was fed a diet high in polyunsaturated fatty acids (PUFA) wherein 9.5% of available calories came from saturated fatty acids (SFA). Group 2 was fed a diet wherein 28.8% of calories came from SFA. Plasma fatty acids, serum lipid profiles, insulin, inflammatory markers, systolic and diastolic blood pressure, and cardiac function parameters were measured. Serum lipids, SFA, and insulin did not differ between the two groups, although omega-3 fatty acids differed. Bears eating the SFA diet had significantly higher circulating adiponectin, interleukin-7 and interleukin-15, and tumor necrosis factor-alpha. Mild, asymptomatic systolic and diastolic dysfunctions were detected by strain echocardiography in the SFA group. The SFA diet group exhibited higher diastolic arterial pressures. Even though mild metabolic derangements were observed, grizzly bears were remarkably resistant to metabolic effects of diets high in SFA.

A grizzly bear from the Middle Wisconsin of Woodbridge, Ontario

1976 ◽  
Vol 13 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Charles S. Churcher ◽  
Alan V. Morgan
Keyword(s):  
Ursus Arctos ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Bone Fragment ◽  
Mammuthus Primigenius ◽  
Ursus Arctos Horribilis ◽  
Before And After ◽  
Lake Simcoe ◽  
Left Humerus ◽  
Woolly Mammoth

The distal end of the left humerus of a grizzly bear, Ursus arctos, has been recovered from above the Early Wisconsin Sunnybrook Till at Woodbridge, Ontario, from the same horizon that previously has yielded remains of the woolly mammoth, Mammuthus primigenius. The age of these specimens is estimated at 40 000–50 000 years BP, within the mid-Wisconsin, Port Talbot Interstadial. The only other recognized Canadian record of a grizzly bear east of Manitoba is from a gravel sequence at Barrie, near Lake Simcoe, Ontario, dated from a bone fragment to 11 700 ± 250 years BP. A specimen recovered in Toronto in 1913 from an Early Wisconsin horizon is also considered to represent the grizzly. Bears of the grizzly type, Ursus arctos-horribilis were present in Ontario before and after the Early and Late Wisconsin ice advances.

Grizzly bear digging sites for Hedysarum sulphurescens roots in southwestern Alberta

1984 ◽  
Vol 62 (12) ◽  
pp. 2571-2575 ◽  
Author(s):  
Anne C. Holcroft ◽  
Stephen Herrero
Keyword(s):  
Discriminant Function ◽  
Discriminant Function Analysis ◽  
Ursus Arctos ◽  
Function Analysis ◽  
Soil Surface ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Rock Fragments ◽  
Ursus Arctos Horribilis ◽  
Steep Slopes

Characteristics of sites where Hedysarum sulphurescens Rydb. roots were extensively, less extensively, or not dug by grizzly bears Ursus arctos horribilis Ord. were analyzed in relation to topographic, vegetative, soil, and geologic features. Discriminant function analysis significantly separated dug and undug sites, but did not separate extensively and less extensively dug sites. Ease of breaking the soil surface, presence of shaly rock fragments, loose cobble and gravel, and steep slopes were characteristic of dug sites. The abundance of H. sulphurescens appeared less important than the loose nature of the substrate indicating that digging time was important in optimizing energetics.

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