National Research Centre, Microbial Genetics Research Unit, Dokki, Cairo, U.A.R.
The results obtained from the cross AD-D2, arg-D529, le-D6, met-4 x ad-D2, ARG-D529, LE-D6, MET-4 by plating on LM media supplemented with arginine and methionine showed no linkage between the two genes, arg-D529 and met-4 in Schizosaccharomyces pombe.
The results obtained from the same cross gave normal segregation for methionine gene, by plating on LM media supplemented with leucine and methionine while the ratio of LE: le segregation was 2: 1. It did not fit a 3: 1 ratio indicating that the possibility of the existence of suppressors should be excluded.
No leucine-requiring mutants appeared among the progeny by plating on LM supplemented with arginine and leucine. These results were attributed to the existence of a translocation between leucine and methionine regions in the met, arg and le parent and that LE is on a fragment in the ad parent. These assumptions were confirmed in the cross arg-D529, ad-D2 x arg-Al, le-D6 and its reciprocal which produced pseudo-wild-type colony and showed a possible translocation between arginine-Al and leucine-D6 regions indicating that arg-Al might also be located on methionine chromosome.
