Steven W. L'Hernault, PhD

Professor, Department of Biology, Emory College of Arts and Sciences

Chair, Department of Biology, Emory College of Arts and Sciences

Department Website

Graduate Programs

Affiliate Member - Biochemistry, Cell and Developmental Biology
Affiliate Member - Genetics and Molecular Biology

Education

PhD, Yale University, 1984
MA, Hofstra University, 1978
BA, Hofstra University, 1976

Contact Information

Email: bioslh@emory.edu

Phone: 404-727-4234

Address:
O. Wayne Rollins Research Center, Room 2001 1510 Clifton Road NE Atlanta, GA 30322 1940-001-1AC

My laboratory is interested in the proteins and processes required to assemble a fertilization-competent cell surface on spermatozoa. We study spermatogenesis and fertilization in the nematode Caenorhabditis elegans because of its superior genetic and reproductive biological tools. Like mammals, the C. elegans spermatid surface must be remodeled by secretory vesicle fusion in order for cell-cell fusion to occur during fertilization. Consequently, we focus on mutants that are either directly defective in fertilization or defective in the sperm secretory vesicles (analogous the the acrosome in mammalian sperm) that must fuse to generate a fertilization-competent surface. These sperm secretory vesicles fuse with the sperm plasma membrane during activation, when spermatids acquire motility and become fertilization-competent. So far, at least four transmembrane proteins reside in sperm secretory vesicles are placed onto the sperm surface, where they are required to create a fertilization-competent sperm. We have shown that one, SPE-45, is orthologous to mammalian Izumo, which is known to be required for sperm-egg fusion in mammals. We have used CRISPR genome engineering to analyze SPE-45/Izumo chimeric proteins for fertilization competence in C. elegans spe-45 null mutant backgrounds and found that much of the human Izumo-derived Ig domain can functionally replace the SPE-45 Ig domain. We are currently exploiting this "humanized" worm to search for potential male birth control compounds via a high-throughput screen of small molecule libraries. In parallel, we continue to explore C. elegans sperm expressed proteins required for fertilization as, despite 1 billion years since nematodes and humans last shared a common ancestor, at least three of these proteins have convincing orthologs in humans.

Guang-Dan Zhu

Genetics and Molecular Biology

PhD, 2003

"SPE-39 is required for intracellular membrane reorganization during spermatogenesis and many other aspects of Caenorhabditis elegans development"

Samuel Lamitina

Biochemistry, Cell and Developmental Biology

PhD, 2002

"A novel domain Caenorhabditis elegans wee-1.3, a member of the MYT1 kinase family, controls M-phase entry in sperm"

Wesley Lindsey

Genetics and Molecular Biology

PhD, 2002

"spe-10 and spe-21 encode DHHC-CRD zinc finger proteins required for ER/Golgi membrane morphogenesis during Caenorhabditis elegans spermatogenesis"

Katherine Hill-Harfe

Genetics and Molecular Biology

PhD, 2000

"Analyses of spermatogenesis and the role of sperm in reproductive interactions in the nematode genus Caenorhabditis"

Priscilla Arduengo

Cell and Developmental Biology (GDBBS)

PhD, 1997

"Disruption of cytoplasmic partitioning during asymmetric cell divisions in C. elegans spermatogenesis by SPE-4, a member of the presenilin protein family"