Both genetic and biochemical approaches have been used to study the molecular mechanisms by which damaged DNA is repaired in a number of species. The fundamental DNA repair pathways have been functionally conserved for the most part among prokaryotes, lower eukaryotes, and higher eukaryotes, and the proteins and protein families involved in these repair processes show high degrees of amino acid sequence conservation. However, there are also a number of cases in which lack of conservation of particular polypeptides may reveal interesting species-specific differences in how certain repair functions are performed.

The recent completion of the Drosophila genome sequence makes possible a comprehensive determination of the presence or absence of Drosophila proteins with significant sequence similarity to proteins implicated in DNA repair studies carried out in other species. In this analysis, we will focus on specific insights into the Drosophila responses to DNA damage that have come to light through inspection of the genomic sequence, considering in turn various groups of proteins involved in different pathways of repair. A comprehensive list of Drosophila DNA repair genes can be found at http://www. dmrepair. ucdavis. edu.