Abstract
A mutation abolishing photorepair has been localized to map position 56.8 centimorgans on the second chromosome of Drosophila melanogaster. Strains homozygous for the phr allele are totally devoid of photorepair and partially deficient in excision repair. Both defects map to the chromosomal region between pr and c. Since a homozygous phr stock exhibits reduced photoreactivation, the corresponding wild-type allele plays a significant role in UV resistance.
