Abstract
This study presents a comparative molecular and genetic analysis of copy number changes in two hybrids that differ in the extent of homologies at the yeast CUP1 r locus. Hybrid JW1020 is a diploid wherein each parent contributed 12 identical, tandemly arrayed 2.0 kb repeat units. Genomic DNA was isolated from each of the spore colonies in a sample of 202 unselected tetrads. About 11% displayed copy number changes, i.e., increases or decreases of one or more complete units.
Copy changes on a per tetrad basis occurred as often in a single spore colony as changes in each of two spores. Such double changes are rarely reciprocal in character. To account for the observed qualitative and quantitative copy number shifts, we propose a molecular recombinant model that posits partial, incomplete synaptic pairing and gene conversion of the unpairing regions with or without associated crossing over.
A contrasting study centers on the copy number alterations and recombinational events uncovered in a molecular analysis of 140 unselected tetrads generated by two related hybrids. Unlike the hybrid JW1020, these diploid strains carried a seven copy tandem array of 1.1 kb units at the CUP1 r locus in one parental homologue and six copy array of 1.6 kb units flanked by an external Xba site at the corresponding chromosome VIII locus. These natural polymorphic alleles were recovered from industrial yeast strains by conversional genetic procedures and characterized by restrictional analysis. Twenty-nine tetrads exhibit evidence for several different types of recombination events. However, ordinary crossover exchanges are conspicuously absent. We suppose that the repetitious non-homologies generate DNA configurations sufficient to disrupt the effective synapsis over the entire locus. Hence, they precluded homologous exchanges, presumably by preventing the resolution of molecular conversion intermediate via an isomerization reaction. Thus, informational transfer reactions are separable from the resolution of asymmetrical heteroduplex DNA, double strand gap or Holliday structures.
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References
Borts RH, Haber JE (1987) Meiotic recombination in yeast: alteration by multiple heterozygosites. Science 237: 1459–1465
Borts RH, Lichten M, Haber JE (1987) Meiotic gene conversion and cross over between dispersed homologous sequences occurs frequently in Saccharomyces cerevisiae. Genetics 115: 233–246
Fogel S, Welch JW (1982) Tandem gene amplification mediates copper resistance in yeast. Proc Natl Acad Sci USA 79: 5342–5346
Fogel S, Choi T, Kilgore D, Lusnak K, Williamson M (1982) The molecular genetics of non-tandem duplication at ade8 in yeast. Rec Adv Yeast Mol Biol 1: 269–288
Fogel S, Welch JW, Karin M (1983) Gene amplification in yeast: CUP1 copy number regulates copper resistance. Curr Genet 7: 347–355
Fogel S, Welch JW, Maloney DH (1988) The molecular genetics of copper resistance in Saccharomyces cerevisiae — a paradigm for non-conventional yeast. J Basic Microbiol 28 /3: 147–160
Haber JE, Borts RH, Connolly B, Lichten M, Rudin N, White CI (1988) Physical monitoring of meiotic and mitotic recombinations in yeast. Progr Nucl Acid Res Mol Biol 35: 212–259
Hamer DH (1986) Metallothionein. Ann Rev Biochem 55: 913–951
Hawthorne DC, Mortimer RK (1960) Chromosome mapping in Saccharomyces: centromere-linked genes. Genetics 45: 1085–1110
Jackson J, Fink GR (1981) Gene conversion between duplicate elements in yeast. Nature 292: 306–311
Jinks-Robertson S, Petes TD (1985) Negative frequency meiotic gene conversion between repeated genes on non-homologous chromosomes in yeast. Proc Natl Acad Sci USA 82: 3350–3354
Karin M, Najarian R, Haslinger A, Valenzuela P, Welch J, Fogel S (1984) Primary structure and transcription of an amplified genetic locus: the CUP1 locus of yeast. Proc Natl Acad Sci USA 81: 337–341
Klein HL (1984) Lack of association between intrachromosomal gene conversion and reciprocal exchange. Nature 310: 748–753
Klein HL, Petes TD (1981) Intrachromosomal gene conversion in yeast. Nature 289: 144–148
Lichten M, Borts RH, Haber JE (1987) Meiotic gene conversion and crossing over between dispersed homologous sequences occurs frequently in Saccharomvces cerevisiae. Genetics 115: 233–246
Maloney DH, Fogel S (1987) Gene conversion, unequal crossing over and mispairing at a non-tandem duplication during meiosis of Saccharomvces cerevisiae. Curr Genet 12: 1–7
Petes TD (1980) Unequal meiotic recombination within tandem arrays of yeast ribosomal DNA genes. Cell 19: 765–774
Rigby PW, Dieckmann M, Rhodes C, Berg P (1977) Labeling deoxyribonucleic acid to high specific activity in vitro by nick translation with DNA polymerase I. J Mol Biol 113: 237–251
Symington LS, Petes TD (1987) Meiotic recombination within the centromere of a yeast chromosome. Cell 52: 237–240
Symington LS, Petes TD (1988) Expansions and contractions of the genetic map relative to the physical map of yeast. Mol Cell Biol 8 (in press)
Welch JW, Fogel S, Cathala G, Karin M (1983) Industrial yeasts display tandem gene iteration at the CUP1 region. Mol Cell Biol 3: 1353–1361
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© 1989 Springer-Verlag Berlin Heidelberg
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Fogel, S., Welch, J.W., Moloney, D.H. (1989). Meiotic Copy Number Changes at CUP1 r are Mediated by Gene Conversion. In: Lother, H., Dernick, R., Ostertag, W. (eds) Vectors as Tools for the Study of Normal and Abnormal Growth and Differentiation. NATO ASI Series, vol 34. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-74197-5_26
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DOI: https://doi.org/10.1007/978-3-642-74197-5_26
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