A worm germline parts list

The sequencing of the genome of the worm Caenorhabditis elegans has made real worm genomics possible. In the September Molecular Cell, Reinke et al. make good on that promise with a DNA array analysis of 11,917 worm genes (~63% of the genome Mol. Cell 2000, 6:605-616). They define 1,416 genes whose transcription is enriched 1.8- to 104-fold in the worm germline, including 650 sperm-enriched genes, 258 oocyte-enriched genes, and 508 germline-intrinsic genes. Some genes can be picked out of this mountain of data based on their similarity to genes implicated in germline processes in other organisms. But perhaps the most striking finding is that no more than six sperm-enriched and germline-intrinsic genes are found on the X chromosome, compared with the 197 genes that would be expected by chance. This skewed distribution has probably arisen because condensation of the X chromosome in the male germline may impair gene expression.