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Date of Award

9-2012

Document Type

Campus Access

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Animal Biotechnology and Biomedical Sciences

First Advisor

Rafael A. Fissore

Second Advisor

Jesse Mager

Third Advisor

David J. Gross

Subject Categories

Molecular Biology | Physiology

Abstract

Given the indispensable role of Ca2+ release in fertilization, the type 1 inositol 1,4,5- trisphosphate receptor (IP3 R1) is a key regulatory molecule in mediating the cross-talk between cell cycle progress and the Ca2+release machinery in mammalian oocytes. The studies in this thesis addressed several important regulatory aspects of the Ca 2+ release activity at fertilization of mammalian eggs. In chapter I, we found that compromised functionality of IP3 R1 underlay the defective IP3 R1-mediated Ca2+ release in aging eggs. Further, our studies also indicated that modifications on the biochemical status of IP3 R1 by incubation with caffeine have positive effects on the Ca2+ release activity and developmental fate of aging mouse eggs. Thus, these results may help facilitate the invention of a cure that could delay/reverse many of age induced detrimental changes thereby restoring the fertilizability of aged eggs. For the next two chapters we mainly focus on the regulatory role of IP 3 R1 as a significant participant in the early developmental event. Our completed results with the caspase-3 cleaved IP3 R1 indicated that the truncated IP3 R1 might not play a prominent role affecting the Ca2+ homeostasis during the aging process in mouse oocytes due to its rapid turnover rate. Regardless, we confirmed the leaky property of C-IP3 R1 in mouse oocytes and found a novel protective proteolysis pathway in mouse oocytes. Finally development of a system by which we could selectively overexpress IP3 R1 phosphorylation mutants allows us to probe important phosphorylation regulatory mechanisms underlying the [Ca2+ ]i oscillations in mammalian oocytes. Thus the experiments I have done provide valuable information regarding the extensive regulation of the PI pathway, regulation that in aged and non- aged MII eggs, results in a Ca2+ release program that is replete with information.

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