POLARITY OF MEIOTIC GENE CONVERSION IN FUNGI - CONTRASTING VIEWS

The frequency of meiotic gene conversion often varies linearly from on e end of the gene to the other. This phenomenon has been called 'polar ity'. In this review, we will primarily discuss studies of polarity th at have been done in the yeast Sacchacromyces cerevisiae (ARG4 and HIS 4 loci) and in Ascobolus (b2 locus) with an emphasis on possible mecha nisms. The genetic and physical data obtained at these 'hotspots' of r ecombination strongly suggests that the formation of a polarity gradie nt reflects both the frequency of heteroduplex formation and the proce ssing of this recombination intermediate by mismatch-repair-dependent processes.