Mitotic mapping ofSchizosaccharomyces pombe

SUMMARYGenetic mapping by means of mitotic haploidization (induced by parafluoropkenylalanine) and mitotic crossing-over was carried out with the fission yeastSchizosaccharomyces pombe. Thirty-two different genetic markers were involved in this investigation; some meiotic linkage relationships had been previously reported (Leupold, Megnet) for 16 of these loci. Mitotic haploidization experiments resulted in the genetic identification of six chromosomes in the haploid complement.Furthermore, in an attempt to study the mechanism of action of parafluorophenylalanine (pFPA) on mitotic haploidization, pedigree analyses were performed by micromanipulation of diploid cells growing in the presence of pFPA. Haploid cells were detected after 40 hours of contact with the analogue and many lethal pedigree branches were observed. These observations seem to agree with Käfer's (1961) and Lhoa's (1968) suggestion that mitotic haploidization in Fungi is achieved by progressive loss of chromosomes throughout cell divisions.