West Coast Worm Meeting Abstracts - Caenorhabditis elegans ...

THE PROMISE AND PERIL OF GENOMICS: SPERM
DEVELOPMENT AS MODEL SYSTEM
Harold Smith, Marci Millhouse, Sam Ward
University of Arizona, Tucson, AZ 85721
West Coast Worm Meeting 2000
Microarray screening allows the investigator to profile expression patterns on a genome-wide scale.
However, even a successful screen can generate a daunting amount of data. In our effort to identify
genes involved in sperm development, we compared expression levels in fem-3(gf) mutants, which make
only sperm, to fem-1(lf) mutants, which make only oocytes. We identified 650 sperm-enriched genes (as
well as 258 oocyte-enriched genes) out of 11,917 genes screened (see Reinke et al.). Now, how do we
use this information? We have focused our efforts in two areas: 1) obtaining deletion mutations in
potentially interesting genes; and 2) identifying sperm promoter elements and their relevant transcription
factors.
Prior work with the calmodulin inhibitor trifluoperazine (TFP) had implicated Ca++ function in both sperm
activation and motility; therefore, we generated a deletion allele of the sperm-enriched Ca++ channel
gene K01A11.4 (since named spe-39). The spe-39 mutant exhibits reduced fertility and an aberrant
sperm morphology that mimics TFP treatment. We can now examine the role of other spe mutants in
Ca++ sensing, sperm activation, and motility.
We are using an in silico approach to identify potential sperm promoter elements, and molecular and
genetic analyses to confirm functional significance. The algorithm (written by John Anderson, NCBI)
determines which sequences are over-represented in the 5’ upstream sequences of sperm genes
compared to non-sperm genes. One of these sperm-enriched sequences contains two potential binding
sites for the GATA transcription factor elt-1. Prior work has shown that elt-1 is required to specify
hypodermal cell fates in the developing embryo; however, our microarray data also identified elt-1 as a
sperm-enriched gene. Yeast one-hybrid screening demonstrates that elt-1 binds to and activates
transcription from these putative promoter elements. In collaboration with Barbara Page, we are currently
investigating the role of elt-1 in sperm development.
44