[
Genes Dev,
2002]
The CM domain is a cysteine-rich DNA-binding motif first recognized in proteins encoded by the Drosophila set determination gene doublesex (Erdman and Burtis 1993; Zhu et al. 2000). As the name doublesex (dsx) suggests, this gene has functions in both sexes: Its transcripts undergo sex-specific alternative splicing, so that it can encode either a male-specific isoform, DSX(M), or a female-specific isoform, DSX(F) (Baker and Wolfner 1988; Burtis and Baker 1989). These proteins have the same N-terminal DNA-binding domain, but different C termini that confer different regulatory properties on the two forms. The expression of DSX(M) directs male development, and the expression of DSX(F) directs female development, throughout most of the somatic tissues of the fruit fly.
[
Nature,
1994]
Many bacterial genes are organized into operons which are transcribed as polycistronic messenger RNAs. By contrast, eukaryotic genes were thought to be regulated individually and transribed as monocistronic mRNAs. Last year, however, a group led by Tom Blumenthal announced the discovery that the nematode Caenorhabditis elegans uses both the prokaryotic and the eukaryotic patterns of gene organization and transcription. Blumenthal and colleagues have now taken this work further (page 270 of this issue). They describe how they have examined the C. elegans genomic database and found that at least a quarter of the genes seem to be organized into operons.