title: Restoration to the parental genotype of mismatches formed in recombinant DNA heteroduplex.
abstract: Crosses were set up, using the b2 locus of Ascobolus immersus, to detect and measure the restoration of the parental genotype of a chromatid from hetero-duplex. From the results it can be concluded that: (1) restoration occurs, and its frequency is comparable to the frequency of conversion; (2) the relative frequency of conversion and restoration on the two homologous chromatids is that expected if the disparity in conversion to mutant and to wild-type of the marker is caused by the decision whether to excise the mutant or wild-type chain. This decision is the same on both chromatids. However, when all data are pooled, a slight, but significant, excess of conversion over restoration is found. The cause of this in discussed; (3) the absence of an excess of restoration over conversion is taken to imply that, in this system, the length of heteroduplex formed in an event is continuous; (4) these findings support the interpretation of tetrads where a crossover is separated from conversion, that they arise by independent correction giving both conversion and restoration in a heteroduplex tract continuous with the crossover.
authors.affiliation: Department of Genetics, University of Alberta, T6G 2E9, Edmonton, Alberta, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Hastings
authors.forename: A
authors.initials: A
authors.lastname: Kalogeropoulos
authors.forename: J L
authors.initials: JL
authors.lastname: Rossignol