Transcription of class III genes in cell-free extracts from the nematode Caenorhabditis elegans

Using the nematode Caenorhabditis elegans as a model organism, we have prepared cell-free extracts which accurately transcribe cloned homologous 5S RNA genes in vitro. These extracts also transcribe cloned tRNA genes, and actively process the resulting products. Unlike tRNA genes, transcription of 5S DNA shows some species specificity: C. elegans extracts do not transcribe Xenopus 5S RNA genes, nor does a Xenopus extract efficiently transcribe the heterologous nematode 5S DNA. However, addition of limiting amounts of C. elegans fractions permits Xenopus extracts to transcribe nematode 5S RNA genes. This apparent biochemical "complementation" may provide an assay to purify 5S RNA gene-specific factors from C. elegans.