Steven L'HernaultChairman, Professor

Education

• B.A., Hofstra University, 1976
• Ph.D., Yale University, 1984

Research Area

• Genetics, Cell, and Developmental Biology

Graduate Program Affiliation

• Biochemistry, Cell & Developmental Biology
• Genetics and Molecular Biology

Research Description

Spermatozoa in all species, including humans, must create a unique cell surface to participate in fertilization. We have assembled a large collection of Caenorhabditis elegans mutants that are sterile because they have defective spermatogenesis. Like all animals, C. elegans spermatozoa have secretory vesicles (MOs) that fuse with and make the cell surface competent for fertilization. Currently, we study several SPE and FER genes required for MO function and/or cell surface assembly.

The SPE-39 protein is required for MO biogenesis and it defines a new animal-specific protein family required for vesicular trafficking, as we showed for both C. elegans and cultured human cells. The SPE-5 protein encodes a vacuolar-ATPase subunit that participates in acidification of MO secretory vesicles. SPE-5 mutant sperm have MO biogenesis and secretory defects so they cannot fertilize eggs. FER-14 and SPE-42 are transmembrane proteins required for sperm-egg interaction during fertilization; the SPE-42 gene has a mammalian homolog, of unknown function, expressed in testes.

SPE-16 is a ubiquitin E3 ligase that is orthologous to Mind Bomb in vertebrates. Like Mind Bomb in other animals, SPE-16 negatively regulates Notch signaling during C. elegans somatic development. Mind Bomb, like SPE-16, is expressed during mouse spermatogenesis, but how it participates in this process is currently unknown in any species. We are currently determining how SPE-16 functions during C. elegans spermatogenesis by a combination of genetic, molecular and biochemical techniques.

Research Lab Description

We study highly conserved and presumably ancient mechanisms that operate in the germ line to protect and maintain the integrity of the genome across generations. We have identified several of these mechanisms and study them using the nematode C. elegans as a model system.

Publications