Abstract
The HO gene promotes interconversion between a and α mating types. As a consequence, homothallic diploid cells are formed by mating between siblings descended from a single α HO or a HO spore. In order to determine the frequency and pattern of the mating-type switch, we have used a simple technique by which the mating phenotype can be assayed without losing the cell to the mating process itself. Specifically, we have performed pedigree analysis on descendants of single homothallic spores, testing these cells for sensitivity to α-factor.
The switch from α to a and vice versa is detectable after a minimum of two cell divisions. 50% of the clones tested showed switching by the four-cell stage. Of the four cells descended from a single cell, only the oldest cell and its immediate daughter are observed to change mating type. This pattern suggests that one event in the switching process has occurred in the first cell division cycle. Restriction of the switched mating-type to two particular cells may reflect the action of the homothallism system followed by nonrandom segregation of DNA strands in mitosis.
The mating behavior of cells which have sustained a change in mating type due to the HO gene is indistinguishable from that of heterothallic strains.
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Selected References
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- Bücking-Throm E., Duntze W., Hartwell L. H., Manney T. R. Reversible arrest of haploid yeast cells in the initiation of DNA synthesis by a diffusible sex factor. Exp Cell Res. 1973 Jan;76(1):99–110. doi: 10.1016/0014-4827(73)90424-2. [DOI] [PubMed] [Google Scholar]
- Esposito R. E., Frink N., Bernstein P., Esposito M. S. The genetic control of sporulation in Saccharomyces. II. Dominance and complementation of mutants of meiosis and spore formation. Mol Gen Genet. 1972;114(3):241–248. doi: 10.1007/BF01788893. [DOI] [PubMed] [Google Scholar]
- Hereford L. M., Hartwell L. H. Sequential gene function in the initiation of Saccharomyces cerevisiae DNA synthesis. J Mol Biol. 1974 Apr 15;84(3):445–461. doi: 10.1016/0022-2836(74)90451-3. [DOI] [PubMed] [Google Scholar]
- Holliday R., Pugh J. E. DNA modification mechanisms and gene activity during development. Science. 1975 Jan 24;187(4173):226–232. [PubMed] [Google Scholar]
- Hopper A. K., Hall B. D. Mutation of a heterothallic strain to homothallism. Genetics. 1975 May;80(1):77–85. doi: 10.1093/genetics/80.1.77. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MCCLINTOCK B. Controlling elements and the gene. Cold Spring Harb Symp Quant Biol. 1956;21:197–216. doi: 10.1101/sqb.1956.021.01.017. [DOI] [PubMed] [Google Scholar]
- Mackay V., Manney T. R. Mutations affecting sexual conjugation and related processes in Saccharomyces cerevisiae. I. Isolation and phenotypic characterization of nonmating mutants. Genetics. 1974 Feb;76(2):255–271. doi: 10.1093/genetics/76.2.255. [DOI] [PMC free article] [PubMed] [Google Scholar]