FREQUENCY OF MATING-TYPE SWITCHING IN HOMOTHALLIC FISSION YEAST
FREQUENCY OF MATING-TYPE SWITCHING IN HOMOTHALLIC FISSION YEAST
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DOI：
10.1038/266172a0
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发表时间：
1977-01-01
期刊：
影响因子：
64.8
通讯作者：
EGEL, R
中科院分区：
文献类型：
--
作者：
EGEL, R
THE genes determining mating type in the fission yeastSchizosaccharomyces pombeare of particular interest in the general study of the genetic control of differentiation. The genetic segments concerned,mat1Mandmat2P, specifying mating type (−) and (+), respectively1, are present, closely linked, in homothallic strains2, but on any one chromatid (that is in thecisposition) they are only expressed in a mutually exclusive manner3. The segments of the mating-type locus,mat1Mandmat2P, govern the transition from vegetative growth to sexual reproduction. They act in a complementary fashion—one functionalMsegment and one functionalPsegment are always required to initiate both conjugation (usually among haploid cells) and meiosis (leading to sporulation in either zygotes or diploid cells), the prominent events in differentiation inS. pombe. A mating-type mutant defective in meiosis but not in conjugation (mat1Mmat2Pm) when crossed with wild type, produces sporulating and non-sporulating zygotes (Fig. 1). These two classes indicate that in individual cells of either parent strain only one or the other mating-type segment is active3. Here I describe a single-cell evaluation of this cross, and show (also by single-cell techniques) that the frequency of mating-type switching in haploid and diploid strains is approximately random. A favoured mechanism for this type of switching is the inversion of a promoter element between the structural genes, the direction of the promoter determining which mating-type segment is switched on.
