[Contribution of correction to genetic recombination in T4-phage measured in 3-factor crosses over indicator distances].

Marker-dependence of recombination in T4 phage was studied in crosses over indicator distance between the markers localized in the short proximal segment of rIIB gene. In three-factor crosses a-b+c- x a+b-c+, the frequencies of recombinants arising as a result of correction of the central marker b to the wild type allele (chi b leads to +) have been determined. The measured values chi b leads to + were found to be in good agreement with the analogous values determined in two-factor crosses. This agreement suggests that in T4 crosses over indicator distances only coupled double exchanges (conversion-like events) are marker-specific and all single exchanges are marker-independent.