Summary
SAD (suppressor of a deficiencies) is a mutation that allows α-mater diploids such as α/α or a1-/α strains to sporulate. This mutation is unstable and reverts to wildtype (sad +) even in strains homozygous for SAD. SAD is dominant to sad +: α/α and a1-/α sad 1/SAD diploids are sporulation-proficient. SAD is located on chromosome III, 40 cM distal to the mating type locus, between THR4 and HMR a. The ability of SAD to support sporulation requires the presence of an α mating type locus with an active α2 function. Possible models for the action of SAD are (1) SAD bypasses the need for a1 function in sporulation, and (2) SAD provides a1 function to MAT a1- mutants by supplying a1 function itself, for example, by allowing expression of a silent copy of MAT a.
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References
Demerec M (1935) Unstable genes. Bot Rev 1:233–248
Gerlach WL (1974) Sporulation in mating-type homozygotes of Saccharomyces cerevisiae. Heredity 32:241–249
Green MM (1977) The case for DNA insertion mutations in Drosophila. In: Bukhari A, Shapiro J, Adhya S (eds) DNA Insertion Elements, Plasmids and Episomes. Cold Spring Harbor Press, Cold Spring Harbor New York, p 437
Haber JE, George JP (1979) A mutation that permits the expression of normally silent copies of mating-type information in Saccharomyces cerevisiae. Genetics 93:13–35
Harashima S, Oshima Y (1976) Mapping of the homothallic genes, HMα and HMa, in Saccharomyces yeasts. Genetics 84:437–451
Hawthorne DC (1963) Directed mutation of the mating type alleles as an explanation of homothallism in yeast. Proc 11th Int Congr Genet 1:34–35
Herskowitz I, Blair I, Forbes D, Hicks J, Kassir Y, Kushner P, Rine J, Sprague G Jr, Strathern J (1980) Control of cell type in the yeast Saccharomyes cerevisiae and a hypothesis for development in higher eukaryotes. In: Loomis W, Leighton T (eds) The Molecular Genetics of Development. Academic Press. New York pp 79–118
Hicks JB (1975) Interconversion of mating types in yeast. Ph.D. Thesis, University of Oregon, Eugene, Oregon
Hicks J, Herskowitz I (1976) Interconversion of mating types in yeast. I. Direct observations of the action of the homothallism (HO) gene. Genetics 83:245–258
Hicks J, Herskowitz I (1977) Interconversion of yeast mating types. II. Restoration of mating ability to sterile mutants in homothallic and heterothallic strains. Genetics 85:373–393
Hicks JB, Strathern JN, Herskowitz I (1977) The cassette model of mating type interconversion. In: Bukhari A, Shapiro J, Adhya S (eds) DNA insertion Elements, Plasmids, and Episomes. Cold Spring Harbor, Cold Spring Harbor Press, New York p 457
Hopper AK, Hall BD (1975a) Mating type and sporulation in yeast. I. Mutations which alter mating-type control over sporulation. Genetics 80:41–59
Hopper AK, Hall BD (1975b) Mutation of a heterothallic strain to homothallism. Genetics 80:77–85
Hopper AK, MacKay V: Control of sporulation in yeast: SAD1 — a mating-type specific, unstable alteration that uncouples sporulation from mating-type control. Mol Gen Genet (in press)
Kassir Y, Simchen G (1976) Regulation of mating and meiosis in yeast by the mating-type region. Genetics 82:187–206
Klar AJS, Fogel S, Radin DN (1979a) Switching of a mating type a mutant allele in budding yeast Saccharomyces cerevisiae. Genetics 92:759–776
Klar AJS, Fogel S, MacLeod K (1979b) MAR1, a regulator of the HM a and HMα loci in Saccharomyces cerevisiae. Genetics 93:37–50
MacKay V, Manney TR (1974a) Mutations affecting sexual conjugation and related processes in Saccharomyces cerevisiae. I. Isolation and phenotypic characterization of non-mating mutants. Genetics 76:255–271
MacKay V, Manney TR (1974b) Mutations affecting sexual conjugation and related processes in Saccharomyces cerevisiae. II. Genetic analysis of nonmating mutants. Genetics 76:273–288
McClintock B (1965) The control of gene action in maize. Brookhaven Symp. Biol 18:162–184
Mortimer RK, Hawthorne DC (1975) Genetic mapping in yeast. In Prescott DM (ed) Methods in Cell Biology Vol. XI, p 221. Academic Press, New York
Rine J, Strathern JN, Hicks JB, Herskowitz I (1979) A suppressor of mating type locus mutations in Saccharomyces cerevisiae: Evidence for and identification of cryptic mating type loci. Genetics 93:877–901
Roman H, Sands SM (1953) Heterogeneity of clones of Saccharomyces derived from haploid ascospores. Proc Natl Acad Sci USA 39:171–179
Simchen G, Piñon R, Salts Y (1972) Sporulation in Saccharomyces cerevisiae. Premeiotic DNA synthesis, readiness and commitment. Exp Cell Res 75:207–218
Strather JN (1977) Regulation of cell type in Saccharomyces cerevisiae. Ph.D. Thesis, University of Oregon, Eugene, Oregon
Takano I, Oshima Y (1970) Mutational nature of an allele-specific conversion of the mating type by the homothallic gene HOα in Saccharomyces. Genetics 65:421–427
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Communicated by G.R. Fink
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Kassir, Y., Herskowitz, I. A dominant mutation (SAD) bypassing the requirement for the a mating type locus in yeast sporulation. Molec. Gen. Genet. 180, 315–322 (1980). https://doi.org/10.1007/BF00425843
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DOI: https://doi.org/10.1007/BF00425843