Distant homology between yeast photoreactivating gene fragment and human genomic digests

Hybridization of DNA coding for the yeast DNA photolyase to human genomic DNA appears to allow one to determine whether a conserved enzyme is coded for in human cells. Under stringent conditions (680C), hybridization is not found between the cloned yeast fragment (YEp13-phr1) and human or chick genomic digests. At less stringent conditions (600C), hybridization is observed with chick digests, indicating evolutionary divergence even among organisms capable of photo-reactivation. At 500C, weak hybridization with human digests was observed, indicating further divergence from the cloned gene. Data concerning the precise extent of homology and methods to clone the chick gene for use as another probe are discussed