<i>Drosophila</i> <i>l(2)23CDe ^A8-1</i> and <i>l(2)23CDf ^A18-2</i> are missense alleles of the <i>SerRS</i> gene.

Viability requires that certain genes are expressed at the correct levels and at specific times during development. Many genes have already been determined as essential to development, but many more may exist. Numerous lethal mutations have been isolated in Drosophila melanogaster that have yet to be identified at the gene level. Here we provide deficiency mapping, complementation testing, and DNA sequencing that suggests the unknown lethal mutations l(2)23CDe A8-1 and l(2)23CDf A18-2 are both missense mutations in the SerRS gene, which encodes an aminoacyl tRNA synthetase that is required for protein translation.