Carl C. Ducummon Graduate Student (Ph. D. Program) Major Professor: Dr. Trish Berger Phone: (530)752-7544 FAX: (530)752-0175 E-mail: carld3@ucdavis.edu

Education

• B.S. Biochemistry, University of Oklahoma, Norman, 1997.
• B.S. Zoology, University of Oklahoma, Norman, 1997.
  Senior Thesis: Changes in Cadherin Protein Localization during Maturation of the Murine Cumulus-Oocyte Complex
• Ph.D. Cell and Developmental Biology, University of California, Davis (In Progress).
  Designated Emphasis in Reproductive Biology

Project

Title: Identification and characterization of a Rho-dependent signaling pathway mediating the porcine acrosome reaction.

Description: The acrosome reaction (AR) is a modified exocytotic event that occurs when the sperm binds to the zona pellucida surrounding the oocyte. The AR is necessary for the sperm to fertilize the egg in vivo. I am interested in understanding the signaling pathway(s) that result in the acrosome reaction.

Many cells undergo exocytosis including mast cells, pancreatic beta cells, and yeast. In these systems, the Rho family of monomeric GTPases has been implicated in regulating exocytosis. From these studies, we hypothesized that a Rho GTPase may play a role in the AR, an exocytotic event.

Recently, I have immunolocalized RhoA in porcine sperm. In washed sperm, RhoA can be seen as staining in the equatorial segment. As the sperm capacitates, staining shifts to the acrosomal cap. This shift correlates with acrosomal status.

Future directions for my work include artificially inhibiting and activating RhoA and evaluating its effect on the acrosome reaction, determining the mechanism by which RhoA translocation occurs, and the effect of modulating Rho activation on the phosphorylation of cytoskeletal elements.