The isolation of male-specific genes and the identification of major sperm protein genes in Caenorhabditis elegans
Differentiation during development and the normal function of eucaryotic cells are dependent on the proper regulation of gene expression. Caenorhabditis elegans, a simple multicellular eucaryote composed of 959 somatic cells, is an ideal organism for the study of gene regulation during development because it is well-suited to both genetic and molecular analyses. In order to facilitate a molecular analysis of gene regulation during spermatogenesis in C. elegans, a cDNA clone bank was made from the polyadenylic acid (poly(A)) RNA of a 70% male population. A group of male-specific genes was isolated from the clone library by differential screening using cDNA probes made from male poly (A) RNA and hermaphrodite poly (A) RNA. From this malespecific gene collection a gene for the major sperm protein 15K was identified by hybrid selected translation and an antibody precipitation test. This 15K cDNA gene was used as a probe which revealed at least 31 additional cDNA clones with homologous sequences. A Southern blot revealed that approximately 15 copies of the gene are present in the genome of C. elegans. A poly(A) RNA blot analysis showed that a 600-nucleotide transcript was present in the male but not in the gravid hermaphrodite. In this study, procedures for the cloning and selection of male-specific genes of the nematode C. elegans have been shown to facilitate the isolation of the major sperm protein gene. These procedures may also be useful in isolating additional sperm protein genes or other genes expressed at specific developmental stages.