GENETIC AND MOLECULAR CHARACTERIZATION OF THE CAENORHABDITIS-ELEGANS SPERMATOGENESIS-DEFECTIVE GENE SPE-17

Two self-sterile mutations that define the spermatogenesis-defective g ene spe-1 7 have been analyzed. These mutations affect unc-22 and fail to complement each other for both Unc-22 and spermatogenesis defects. Both of these mutations are deficiencies (hcDf1 and hDf13) that affec t more than one transcription unit. Genomic DNA adjacent to and includ ing the region deleted by the smaller deficiency (hcDf1) has been sequ enced and four mRNAs (including unc-22) have been localized to this se quenced region. The three non unc-22 mRNAs are shown to be sex-specifi c: a 1.2-kb mRNA that can be detected in sperm-free hermaphrodites and 1.2- and 0.56-kb mRNAs found in males. hDf13 deletes at least 55 kb o f chromosome IV, including all of unc-22, both male-specific mRNAs and at least part of the female-specific mRNA. hcDf1, which is approximat ely 15.6 kb, deletes only the 5' end of unc-22 and the gene that encod es the 0.56-kb male-specific mRNA. The common defect that apparently a ccounts for the defective sperm in hcDf1 and hDf13 homozygotes is dele tion of the spe-17 gene, which encodes the 0. 56-kb mRNA. Strains carr ying two copies of either deletion are self-fertile when they are tran sgenic for any of four extrachromosomal array that include spe-17. We have sequenced two spe-17 cDNAs, and the deduced 142 amino acid protei n sequence is highly charged and rich in serine and threonine, but sho ws no significant homology to any previously determined protein sequen ce.