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Shivering, muscle tone, and uncoupling proteins in a developing marsupial, the Tasmanian bettong (Bettongia gaimardi)

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Kabat, AP and Rose, RW and West, AK (2007) Shivering, muscle tone, and uncoupling proteins in a developing marsupial, the Tasmanian bettong (Bettongia gaimardi). Journal of Thermal Biology, 32 (5). pp. 282-292. ISSN 0306-4565

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Abstract

This study examined the development of several physiological parameters that enable the development of endothermy during pouch
life of the Tasmanian bettong (Bettongia gaimardi). By using several key age groups, we investigated the electromyography response of
pouch young under different thermal conditions (35 or 20 1C), with and without injection of the b-agonist norepinephrine. We also used
molecular techniques to examine the possible expression of uncoupling proteins 1, 2, and 3 (UCP1, 2, and 3), and if they were expressed,
any association these may have with the timing of endothermic development. AT 6 weeks of age, pouch young were unable to
thermoregulate via shivering or non-shivering mean, maintain a constant metabolic rate, or show any response to the b-agonist injection.
When the animals were exposed to a cold stress (20 1C), 8-week-old pouch young initially shivered for 2–3 min before tapering off
completely, causing body temperature to sharply decline. During the 10th week, cold-exposed pouch young began shivering, with the
bout lasting approximately 10 min before ceasing and body temperature beginning to decline. It was also at this age that the expression of
UCP2 was initially expressed. By the 12th week, cold exposed pouch young initially employed classical shivering; however, after
approximately 12 min, this was replaced with an increase in muscular tone. This increase in muscular tone was also recorded in response
to b-agonist injection at thermoneutral this age and was associated with an increase in metabolic rate. Also by this age, total body fat
increased by approximately 300% from the levels expressed at 6 weeks of age and UCP2 was significantly upregulated. Although pouch
young B. gaimardi did not show UCP1 expression at any time, UCP3 was expressed at every age investigated from 6 weeks of age. This
study proposes that pouch young B. gaimardi use a mechanism of increased muscle tone as a source of heat production, and shows that
UCP2 has an association with the onset of thermogenesis.

Item Type: Article
Keywords: Marsupial; Endothermy; Development; Uncoupling proteins; Muscle tone; Shivering; Bettongia gaimardi
Journal or Publication Title: Journal of Thermal Biology
Page Range: pp. 282-292
ISSN: 0306-4565
Identification Number - DOI: 10.1016/j.jtherbio.2007.02.003
Additional Information:

The definitive version is available at http://www.sciencedirect.com

Date Deposited: 31 Jul 2008 04:56
Last Modified: 18 Nov 2014 03:46
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