Gene Conversion in the Pasadena Strain of ASCOBOLUS IMMERSUS.

TUDIES on a strain of Ascobotus immersus collected in Pasadena, California ( Y u S U N 1964) have shown unusually high rates of gene conversion at a number of sites of white-spored mutations. In most such examples conversion ratios 5 t : 3w (wild type: white) and especially 3+: 5w have been common. Closely linked sites frequently have had very similar distributions of the different conversion ratios. In some instances mutants recovered following gene conversion (e.g., two of the six white segregants in 2+:6w asci) have characteristics considerably altered from those of the parental mutant, and from mutants recovered following regular segregation. Some of the data to be reported have a bearing on the lengths of regions undergoing repair-assuming that repair is the mechanism actually responsible for gene conversion ( HOLLIDAY 1964; WHITEHOUSE and HASTINGS 1965; and others).