Time-dependent changes in gene conversion inAscobolus immersus

Abstract

SummaryThe stability of conversion frequencies with time was investigated inAscobolus immersus. There were usually marked reductions in gene conversion frequencies at locuswlas crosses matured, to about one third of the initial values. This applied to all sixwlalleles tested, irrespective of their molecular nature, and at all temperatures used. Asci dehiscing early from an apothecium had much higher conversion frequencies than those dehiscing late, but there were no differences between apothecia maturing at different times within a cross. Alleles at four loci unlinked towlwere also tested. All four showed significant changes, though not in all crosses; three loci showed decreases in conversion frequency with time, while one showed an increase. The relative frequencies of different conversion classes often changed with time. These changes appear to result from alterations in locus-specific recombination initiation and in repair of base mispairs in hybrid DNA, not from differential maturation rates of different ascal segregation classes. These effects could cause misinterpretation of quantitative tests of recombination models from gene conversion data.