Genetic analysis of dar, uvsW, and uvsY in bacteriophage T4: dar and uvsW are alleles.

A genetic study of the T4 dar (DNA arrested synthesis restoration) mutations was performed by two- and three-factor crosses. The dar mutations restore the viability of gene 59 mutants. Mapping studies of the dar mutations indicated that the dar gene extended over 16 map units. This high recombination frequency is attributed to an increased level of recombination in the dar region. Two other mutations, uvsY and uvsW, known to be located in the vicinity of dar, were studied. These studies indicated that the uvsY and dar mutations were located in separate genes but that dar and uvsW were allelic. The genes are ordered as follows: gene 24, dar(uvsW), uvsY, and gene 25 in clockwise order.