Award Date

1-1-2008

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Life Sciences

First Committee Member

Allen Gibbs

Number of Pages

112

Abstract

Protein synthesis is virtually non-existent during hibernation in golden-mantled ground squirrels. In the presence of negligible protein synthesis continued protein degradation would disrupt the maintenance of homeostasis and the survival of the animal. Earlier investigation showed that ubiquitin conjugate concentrations increase 2-3 fold during hibernation, which would seemingly suggest an increase of protein degradation. In this study I examined protein degradation per se as a function of the temperatures experienced by the hibernator and demonstrated that protein degradation is virtually absent at low temperatures. A new method was developed to determine the rates of ubiquitylation as a function of temperature, and it was demonstrated that ubiquitylation continues at 30% of maximum even at 0° C. The quality of the ubiquitylation was also examined and revealed no significant change between the torpor states. These results may explain the increase in ubiquitin conjugates during hibernation as a simple accumulation event. Contrary to the common belief that hibernators are perfectly adapted for hibernation, this study demonstrates that this may not be correct. The apparent mismatch to the temperature effects between protein degradation and the levels of ubiquitin conjugates demonstrates that hibernating animals may employ the temperature, albeit not perfectly, to down-regulate important homeostatic processes. The consequences of this mismatch may be the reason for the existence of the interbout arousals.

Keywords

Cathepsins; Degradation; Hibernation; Lateralis; Lysosomes; Mammalian; Monoubiquitylation; Protein; Protein Degradation; Spermophilus Lateralis; Squirrels

Controlled Subject

Cellular biology; Molecular biology; Physiology

File Format

pdf

File Size

1761.28 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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