Active Season Changes in Resting Metabolic Rate and Body Condition of Free-living Arctic Ground Squirrels PDF Download
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Author: Robert W. Fridinger
Publisher:
ISBN:
Category : Arctic ground squirrel
Languages : en
Pages : 144
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Book Description
Body mass and condition and resting metabolism were assessed in a natural population of adult male and female arctic ground squirrels (AGS) living near Toolik Lake, Alaska. Assessed by the deuterium dilution method, body condition of AGS was at a low in May, but sexes differed in timing and patterns of fat and lean mass (LM) gain before immergence. Lipid mass increased sevenfold, accounting for the majority of body mass increase. Fuel use, estimated by respirometry, shifted from fat to carbohydrate over the active season. Resting metabolic rate (RMR) was at an active season low in May, reached a maximum in July and decreased before immergence in Aug-Sept. RMR declined only after peak mass was attained, suggesting that RMR reduction is not important for prehibernation fattening. RMR was modulated by the amount of LM present in males. Females reduced nocturnal body temperature and energy expenditure before initiating hibernation.
Author: Robert W. Fridinger
Publisher:
ISBN:
Category : Arctic ground squirrel
Languages : en
Pages : 144
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Book Description
Body mass and condition and resting metabolism were assessed in a natural population of adult male and female arctic ground squirrels (AGS) living near Toolik Lake, Alaska. Assessed by the deuterium dilution method, body condition of AGS was at a low in May, but sexes differed in timing and patterns of fat and lean mass (LM) gain before immergence. Lipid mass increased sevenfold, accounting for the majority of body mass increase. Fuel use, estimated by respirometry, shifted from fat to carbohydrate over the active season. Resting metabolic rate (RMR) was at an active season low in May, reached a maximum in July and decreased before immergence in Aug-Sept. RMR declined only after peak mass was attained, suggesting that RMR reduction is not important for prehibernation fattening. RMR was modulated by the amount of LM present in males. Females reduced nocturnal body temperature and energy expenditure before initiating hibernation.
Author: Trixie Nicole Lee
Publisher:
ISBN:
Category : Marmots
Languages : en
Pages : 240
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Book Description
The Arctic is home to animals that have taken adaptations to overwintering to extremes. In this dissertation, I have investigated one of these adaptations, hibernation, in two species from the Arctic, the Alaska marmot (Marmota broweri) and the arctic ground squirrel (Urocitellus parryii). The expression of hibernation under natural conditions in these species was compared by collecting body temperature records of free-living individuals. The Alaska marmot, a highly social species, demonstrated extreme synchrony in body temperature patterns among a family group, indicating a strong reliance on social thermoregulation. In contrast, the arctic ground squirrel was confirmed to be a solitary hibernator that reduces body temperature below freezing during torpor. Both species must produce heat when soil temperatures are significantly below freezing for most of the winter. At these subfreezing ambient temperatures, the arctic ground squirrel has shown an increasing reliance on nonlipid fuel during torpor, driving a loss of lean mass during hibernation of ~20%. I calibrated deuterium dilution to repeatedly estimate body composition in this species, which dramatically changes adiposity through its annual cycle, and used this technique to quantify lean mass loss throughout hibernation in a study of tissue metabolism. I also developed and applied the natural abundance of nitrogen and carbon stable isotopes as tools for monitoring differential tissue metabolism and differentiating mixed metabolic fuel use in the arctic ground squirrel. These data clarified the mechanism of change in nitrogen stable isotopes andd, indicated that hibernating ground squirrels rebuild organ tissues while breaking down muscle tissue to meet energetic demands. Furthermore, I corroborated a shift in metabolic fuel use toward nonlipid sources during torpor at low ambient temperatures by using the carbon isotope ratio in exhaled breath in combination with respiratory quotient. This dissertation combines studies of hibernation patterns in free-living animals with experimental data on the tissues and fuels being catabolized at very low temperatures to broaden our understanding of how small mammals successfully hibernate in severe winter conditions. It also presents the development and use of stable isotope ratios as physiological tools in hibernating species.
Author: Thomas Ruf
Publisher: Springer Science & Business Media
ISBN: 364228678X
Category : Science
Languages : en
Pages : 549
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Book Description
This book summarises the newest information on seasonal adaptation in animals. Topics include animal hibernation, daily torpor, thermoregulation, heat production, metabolic depression, biochemical adaptations, neurophysiology and energy balance. The contributors to this book present interdisciplinary research at multiple levels ranging from the molecular to the ecophysiological, as well as evolutionary approaches. The chapters of this book provide original data not published elsewhere, which makes it the most up-to-date, comprehensive source of information on these fields. The book’s subchapters correspond to presentations given at the 14th International Hibernation Symposium in August 2012 in Austria. This is a very successful series of symposia (held every four years since 1959) that attracts leading researchers in the field. Like the past symposia, this meeting – and consequently the book – is aimed not only at hibernation but at covering the full range of animal adaptations to seasonal environments. For the next four years, this book will serve as the cutting-edge reference work for graduate students and scientists active in this field of physiology and ecology. .
Author: Gerhard Heldmaier
Publisher: Springer Science & Business Media
ISBN: 3662041626
Category : Science
Languages : en
Pages : 534
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Book Description
This book contains the proceedings of the 11 'h international symposium dedicated to the understanding of animal "Life in the Cold", held at Jungholz (Austria), August 13-18, 2000. In 55 chapters contributed by researchers from 16 countries the current state of knowledge is reviewed, and the most recent developments and discussions in this field are highlighted. The first symposium on hibernation and life in the cold was held in 1959, and from then on they continued to occur every 3-5 years. The regular occurrence of these meetings became almost a tradition. A tradition which is entirely based on the enthusiasm of participants, and was nourished by scientific progress in this area during the past decades. The first symposium in 1959 was organised by Charles P. Lyman and Albert R. Dawe and was almost entirely dedicated to hibernation and torpor. This has been a backbone topic of the following symposia, although other aspects of animal energetics, thermal physiology and biochemistry were included in later meetings.
Author: Sylvain Giroud
Publisher: Frontiers Media SA
ISBN: 2832550622
Category : Science
Languages : en
Pages : 138
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Book Description
Torpor or heterothermy corresponds to a state of depressed metabolism and is associated with specific metabolic, cellular and molecular adaptations that often occur on a seasonal basis. Yet the exact mechanisms and functioning of these changes are poorly understood. Interestingly, the potential of such extraordinary animal adaptation for human and animal health as well as other biomedical considerations has raised particular attention especially in the last decade. The strong metabolic and physiological adaptations of heterotherms can be of particular inspiration for current biomedical and pathological situations (e.g., obesity and related diseases, cardiovascular and metabolic dysfunctions, ischemia-reperfusion injuries, immune depression) and for the health and longevity of animal species, including humans.
Author: Shawna Karpovich
Publisher:
ISBN:
Category : Arctic ground squirrel
Languages : en
Pages : 158
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Book Description
"Arctic ground squirrels (Spermophilus parryii kenicotti) hibernate underground; experiencing burrows temperatures of -5 to -25C̊. Hibernation consists of 7-9 months of torpor interrupted every 2-3 weeks by 10-20 h arousal episodes with high body temperatures and metabolic rates. Metabolic rates and body temperatures were measured during arousal episodes under temperate and arctic conditions. No difference in cost of arousal episodes was detected. Yet, when the cost of thermogenesis during torpor was included, proportional cost of arousal episodes decreased from 86 to 27% comparing temperate to arctic conditions. The relationship between metabolic rate and body temperature was examined during the recooling phase of hibernation. As animals entered torpor, body temperature was allowed to either decrease naturally or was experimentally altered at different points along the recooling curve. The changes in metabolic rate can be explained by changes in body temperature and no sign of temperature-independent metabolic suppression was detected"--Leaf iii.
Author: Roberto Refinetti, PhD.
Publisher: CRC Press
ISBN: 1466514981
Category : Medical
Languages : en
Pages : 738
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Book Description
Circadian rhythms influence most of our life activities, notably getting up and going to sleep every day. This new edition of Circadian Physiology delves into the mechanisms surrounding how these rhythms work, the physiology and biology behind them, and the latest research on this cutting-edge field. The book also discusses a wide variety of practi
Author: Trixie Nicole Lee
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages : 120
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Book Description
The Artic is home to animals that have taken adaptations to overwintering to extremes. In this dissertation, I have investigated one of these adaptations, hibernation, in two species from the Artic, the Alaska marmot (Marmota broweri) and the artic ground squirrel (Urocitellus parryii). The expression of hibernation under natural conditions in these species was compared by collecting body temperature records of free-living individuals. The Alaska marmot, a highly social species, demonstrated extreme synchrony in body temperature patterns among a family group, indicating a strong reliance on social thermoregulation. In contrast, the artic ground squirrel was confirmed to be a solitary hibernator that reduces body temperature below freezing during torpor. Both species must produce heat when soil temperatures are significantly below freezing for most of the winter. At these subfreezing ambient temperatures, the artic ground squirrel has shown an increasing reliance on nonlipid fuel during torpor, driving a loss of lean mass during hibernation of ~20%. I calibrated deuterium dilation to repeatedly estimate body composition in this species, which dramatically changes adiposity through its annual cycle, and used this technique to quantify lean mass loss throughout hibernation in a study of tissue metabolism. I also developed and applied the natural abundance of nitrogen and carbon stable isotopes as tools for monitoring differential tissue metabolism and differentiating mixed metabolic fuel use in the artic ground squirrel. These data clarified the mechanism of change in nitrogen stable isotopes and indicated that hibernating ground squirrels rebuild organ tissues while breaking down muscle tissue to meet energetic demands. Furthermore, I corroborated a shift in metabolic fuel use toward nonlipid sources during torpor at low ambient temperatures by using the carbon isotope ratio in exhaled breath in combination with respiratory quotient. This dissertation combines studies of hibernation patterns in free-living animals with experimental data on the tissues and fuels being catabolized at very low temperatures to broaden our understanding of how small mammals successfully hibernate in severe weather conditions. It also presents the development and use of stable isotope ratios as physiological tools in hibernating species.
Author: Carla Frare
Publisher:
ISBN:
Category : Arctic ground squirrel
Languages : en
Pages : 390
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Book Description
Hibernation is a unique adaptation to conserve energy entering a hypometabolic (low metabolic rate) and hypothermic (low body temperature) state called torpor. Torpor is characterized by a drop in metabolism to 1-2% of basal metabolic rate and a decrease in body temperature to one to two degrees above ambient temperature. Metabolic rate is restored to basal metabolic rate and body temperature increases from 2-30C to 360C during the regularly timed arousal. The adenosine A1 receptor agonists promote the onset of hibernation and torpor in different species, through a yet undefined neuronal circuit. In the Arctic ground squirrel, CHA, an adenosine A1 receptor agonist, induces hibernation during the winter- hibernation season but not in summer even when the environmental conditions are kept constant (ambient temperature of 20C and a light cycle of 4L:20D). Thus, the phenomenon of CHA-induced hibernation is entrained to an endogenous circannual rhythm. In this work, I aim to identify the changes in neuronal activation that reflect the circannual rhythm regulating the seasonal difference in response to CHA. Arctic ground squirrels, housed at constant ambient temperature (2°C) and light cycle (4L:20D), were implanted with body temperature transmitters. I collected tissue during Summer, Fall, Winter and Torpor conditions for seasonal analysis. For treatment analysis, I collected tissue form animals treated with CHA or vehicle in Summer and Winter. Primarily, I used immunohistochemistry to identify cell groups affected by season and treatment. I used cFos to identify neuronal activity and other immunohistochemical markers to identify neuronal phenotypes, based on specific cytoplasmic proteins. An overall seasonal decrease in thermogenesis, measured as reduced neuronal activity in the thermoregulatory pathways, and increase in vasoconstriction reflected the higher order processing necessary for CHA-induced hibernation. CHA inhibited the histaminergic neurons in the hypothalamus suppressing wakefulness and dis-inhibited the nucleus tractus solitarius, further suppressing thermogenesis. Preliminary data also suggested a seasonal change in the adenosine metabolic pathway, which may have increased adenosine receptor sensitivity during the hibernation season. Our results suggest that histaminergic neurons in the hypothalamus and the nucleus tractus solitarius are likely targets to manipulate metabolic demand in the clinical setting inducing therapeutic hypothermia or increasing metabolic rate.
Author: Charles P Lyman
Publisher: Elsevier
ISBN: 0323138241
Category : Nature
Languages : en
Pages : 332
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Book Description
Hibernation and Torpor in Mammals and Birds explores the physiological factors that control hibernation and torpor in birds and mammals. This text covers topics ranging from metabolism in hibernation to the role of endocrines, respiration and acid-base state in hibernation, and theories of hibernation. This book is comprised of 14 chapters and begins with an overview of some clear-cut definitions and why mammals and birds hibernate. The reader is then introduced to the variations from euthermia that have been observed among birds and mammals. To give some structure to this listing, the approach is phylogenetic, starting with the birds and proceeding through the primitive to the more advanced mammals. Subsequent chapters explains the process of entering hibernation and the hibernating state, itself; capability of a species in natural hibernation to arouse from that state using self-generated heat; physiological changes at the start of a spontaneous arousal; and physiological mechanisms underlying the ability of hibernators to rewarm. Consideration is also given to intermediary metabolism in hibernation, cold adaptation of metabolism in hibernators, and the response of hibernators to various extrinsic influences such as neoplastic growth, radiation injury, and parasitism and symbionts. This book will be of interest to students and researchers in fields ranging from zoology to physiology and biophysics.
