Hostname: page-component-586b7cd67f-dlnhk Total loading time: 0 Render date: 2024-11-26T22:30:24.255Z Has data issue: false hasContentIssue false
  • English
  • Français

Genetic analysis of recombination at the g locus in Sordaria fimicola

Published online by Cambridge University Press:  14 April 2009

H. L. K. Whitehouse
H. L. K. Whitehouse
Affiliation:
Botany School, University of Cambridge
Rights & Permissions [Opens in a new window]

Summary

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Interallelie crosses of mutants at the grey (g) spore colour locus in Sordaria fimicola, heterozygous for flanking markers, give rise to a large number of aberrant ascus genotypes, 45 of which can arise through relatively simple events and have been chosen for study. These genotypes comprise 50–75% of the aberrant asci, depending on the mutants crossed.

Comparison of the results from 10 pairwise crosses involving 7 alleles reveals that linked postmeiotic segregation and co-conversion decrease rapidly in frequency with increasing separation of the mutant sites.

The data from reciprocally recombinant asci, from asci with normal segregation at one of the two mutant sites, and from flanking marker behaviour in one- and two-point crosses, agree with the Holliday-Sobell formulation, with the following additional features:

(1) The nuclease, which nicks homologous polynucleotides and then degrades one of the two nicked chains when a mutant enters the hybrid DNA structure, can show preferential degradation of the mutant (or the wild-type) chain. In addition, a second nuclease is involved in the excision-repair process that introduces an additional preferential (marker specific) bias in the degradation of the mutant (or the wild-type) chain. This could explain why asci with odd-ratio conversion (5:3 and 3:5 ratios) sometimes show a different bias, as first reported by Emerson for Ascobolus, from those with even-ratio conversion (6:2 and 2:6 ratios), since the latter but not the former require, in addition, the action of a mismatch correction enzyme to account for them.

(2) The migratory hybrid DNA structure which enters the gene at one end may be of a different size from that which enters from the other end.

(3) Mismatch correction at the end of the hybrid DNA structure leads to a non-recombinant outside marker genotype and modifies the 1:1 ratio of parental:recombinant flanking markers that is otherwise found.

Type
Research Article
Information
Genetics Research , Volume 24 , Issue 3 , December 1974 , pp. 251 - 279
Copyright
Copyright © Cambridge University Press 1974

References

REFERENCES

Bond, D. J. (1973). Polarity of gene conversion and post-meiotic segregation at the buff locus in Sordaria brevicollis. Genetical Research 22, 279–289.CrossRefGoogle ScholarPubMed
Carlson, P. S. (1970). A genetic analysis of the rudimentary locus of Drosophila melanogaster. Ph.D. Dissertation, Yale University.Google Scholar
Carlson, P. S. (1971). A genetic analysis of the rudimentary locus of Drosophila melanogaster. Genetical Research 17, 53–81.CrossRefGoogle Scholar
Case, M. E. & Giles, N. H. (1959). Recombination mechanisms at the pan-2 locus in Neurospora crassa. Cold Spring Harbor Symposia on Quantitative Biology 23, 119–135.CrossRefGoogle Scholar
Emerson, S. (1966). Quantitative implications of the DNA-repair model of gene conversion. Genetics 53, 475–485.CrossRefGoogle ScholarPubMed
Fields, W. G. & Olive, L. S. (1967). The genetics of Sordaria brevicollis. III. Gene conversion involving a series of hyaline ascospore color mutants. Genetics 57, 483–493.CrossRefGoogle Scholar
Fincham, J. R. S. (1967). Recombination within the am gene of Neurospora crassa. Genetical Research 9, 49–62.CrossRefGoogle Scholar
Fogel, S. & Hurst, D. D. (1967). Meiotic gene conversion in yeast tetrads and the theory of recombination. Genetics 57, 455–481.CrossRefGoogle ScholarPubMed
Fogel, S., Hurst, D. D. & Mortimer, R. K. (1971). Gene conversion in unselected tetrads from multipoint crosses. Second Stadler Symposium, Columbia, Missouri, pp. 89–110.Google Scholar
Fogel, S. & Mortimer, R. K. (1969). Informational transfer in meiotic gene conversion. Proceedings of the National Academy of Sciences of the U.S.A. 62, 96–103.CrossRefGoogle ScholarPubMed
Gutz, H. (1971). Site specific induction of gene conversion in Schizosaccharomyces pombe. Genetics 69, 317–337.CrossRefGoogle ScholarPubMed
Holliday, R. (1964). A mechanism for gene conversion in fungi. Genetical Research 5, 282–304.CrossRefGoogle Scholar
Kitani, Y. & Olive, L. S. (1967). Genetics of Sordaria fimicola. VI. Gene conversion at the g locus in mutant × wild type crosses. Genetics 57, 767–782.CrossRefGoogle Scholar
Kitani, Y. & Olive, L. S. (1969). Genetics of Sordaria fimicola. VII. Gene conversion at the g locus in interallelic crosses. Genetics 62, 23–66.CrossRefGoogle Scholar
Kitani, Y. & Whitehouse, H. L. K. (1974 a). Effect of the proportion of parental nuclei in a heterokaryon on the pattern of gene conversion in Sordaria fimicola. Molecular and General Genetics 131, 47–56.CrossRefGoogle Scholar
Kitani, Y. & Whitehouse, H. L. K. (1974 b). Aberrant ascus genotypes from crosses involving mutants at the g locus in Sordaria fimicola. Genetical Research 24, 229–250.CrossRefGoogle Scholar
Lissouba, P., Mousseau, J., Rizet, G. & Rossignol, J.-L. (1962). Fine structure of genes in the ascomycete Ascobolus immersus. Advances in Genetics 11, 343–380.CrossRefGoogle Scholar
Murray, N. E. (1963). Polarized recombination and fine structure within the me-2 gene of Neurospora crassa. Genetics 48, 1163–1183.CrossRefGoogle ScholarPubMed
Rossignol, J.-L. (1967). Contribution à l'étude des phénomènes de recombinaison intra-géque. These, Université de Paris. 167 pp.Google Scholar
Sigal, N. & Alberts, B. (1972). Genetic recombination: the nature of a crossed strand-exchange between two homologous DNA molecules. Journal of Molecular Biology 71, 789–793.CrossRefGoogle ScholarPubMed
Smith, B. R. (1965). Interallelic recombination at the his-5 locus in Neurospora crassa. Heredity 20, 257–276.CrossRefGoogle ScholarPubMed
Sobell, H. M. (1972). Molecular mechanism for genetic recombination. Proceedings of the National Academy of Sciences of the U.S.A. 69, 2483–2487.CrossRefGoogle ScholarPubMed
Sobell, H. M. (1973). Symmetry in protein-nucleic acid interaction and its genetic implications. Advances in Genetics 17, 411–490.CrossRefGoogle ScholarPubMed
Spatz, H. C. & Trautner, T. A. (1970). One way to do experiments on gene conversion? Transfection with heteroduplex SPP1 DNA. Molecular and General Genetics 109, 84–106.CrossRefGoogle Scholar
Stadler, D. R. & Towe, A. M. (1971). Evidence for meiotic recombination in Ascobolus involving only one member of a tetrad. Genetics 68, 401–413.CrossRefGoogle ScholarPubMed
Webber, B. B. (1965). Genetical and biochemical studies of histidine-requiring mutants of Neurospora crassa. IV. Linkage relationships of hist-3 mutants. Genetics 51, 275–283.CrossRefGoogle ScholarPubMed
Whitehouse, H. L. K. (1967). Secondary crossing-over. Nature 215, 1352–1359.CrossRefGoogle ScholarPubMed
Whitehouse, H. L. K. & Hastings, P. J. (1965). The analysis of genetic recombination on the polaron hybrid DNA model. Genetical Research 6, 27–92.CrossRefGoogle ScholarPubMed