The availability of complete genome sequences has fostered the development of technologies to take advantage of that information. Those technologies provide exciting opportunities to approach longstanding biological questions from new directions. We would like to better understand the process of sperm development as an example of cellular differentiation. To that end, we have used DNA microarrays of the complete genome to examine gene expression profiles during germ cell differentiation. By comparing synchronized
fem-1 and
fem-3(gf) adult hermaphrodites, we identified a large number of genes up-regulated during oogenesis or spermatogenesis. We compiled a database of potential promoters that consisted of the upstream DNA sequence for each of ~19,000 predicted genes, and compared those sequences from the sperm-enriched vs. non-enriched classes to identify over-represented sequence elements. One of those elements was present in the upstream region of a large fraction of the most highly expressed sperm genes. We used that element as a target binding site in a yeast one-hybrid screen to isolate the cognate binding factor, and recovered the
elt-1 gene. Prior work has shown that
elt-1, which encodes a GATA transcription factor, is required for hypodermal cell fates. Abundant expression of
elt-1 in the sperm-producing germ line has been reported; consistent with that observation, we found that a promoter containing the
elt-1 binding element drives expression of a GFP transgene in sperm, and deletion of that element abolishes GFP expression. Zygotic lethality of the existing
elt-1 mutation precludes the demonstration of its role in sperm gene expression; therefore, we used RNAi feeding to investigate additional functions of
elt-1. Young adult hermaphrodites raised on bacteria expressing
elt-1 dsRNA produced dead embryos indistinguishable from
elt-1 mutants; however, RNAi feeding of L1 hermaphrodites produced adults with a partially penetrant sperm-specific sterility. RNAi feeding of L1 males produced sterile adults with morphologically defective sperm. These results demonstrate a functional role for
elt-1 in sperm development, presumably via transcriptional induction of a number of sperm genes.