Date Thesis Awarded

5-2015

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Diane Shakes

Committee Member

Shantá Hinton

Committee Member

Lizabeth Allison

Committee Member

Douglas Young

Abstract

To acquire motility, Caenorhabditis elegans sperm must undergo the

regulated cellular remodeling process of sperm activation, but in the complete

absence of new protein synthesis. Nematode sperm utilize two general

mechanisms to overcome this obstacle: 1) They pre-package many proteins

involved in this remodeling and subsequent sperm motility within the unique

Fibrous Body-Membranous Organelle (FB-MOs) complexes; 2) They employ

large numbers of protein kinases and phosphatases, including SPE-6, in the

acquisition and regulation of motility. Genetically, spe-6 is represented by two

classes of alleles. In null alleles, spermatocytes fail to assemble FB-MOs or

complete their meiotic divisions. In a second class of special alleles,

spermatocytes complete their meiotic divisions, but mutant sperm activate

precociously in the absence of proper extracellular signals.

In this study, we contextualize SPE-6 evolutionarily by demonstrating that

SPE-6 is closest in sequence homology to Tau Tubulin Kinases and that SPE-6

itself is highly conserved throughout Nematoda. We then report the first

description of the dynamic sub-cellular localization pattern of SPE-6 and how this

pattern changes at key steps of C. elegans sperm development. Specifically,

SPE-6 localization dramatically shifts during disassembly of FB-MOs and during

sperm activation. Furthermore, we characterize spe-6 sperm activation alleles at

the protein and phenotypic level to determine that mis-localization or partial loss

of SPE-6 expression is sufficient to induce precocious sperm activation. We

further examine SPE-6 localization under a number of genetic, pharmacological,

and physiological conditions and reveal that SPE-6 localization is context

dependent in activated sperm. Finally, we demonstrate that SPE-6 localization

changes during sperm activation correlate to a change in phosphorylation state.

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