Summary
Mapping within the am gene of Neurospora crassa is possible only because of a marked polarity of conversion within the gene, seen in the unequal frequencies of the two parental flanking marker combinations among the selected intragenic recombinants. The conventional comparison of the frequencies of the two flanking marker recombinant classes gives only uncertain and conflicting indications of the orientation of sites within the gene. While other possible interpretations are not ruled out, it is suggested that one relatively simple way of explaining the data is to suppose (a) that most recombination within am is due to conversion without immediately associated crossing-over, and (b) that recombinational events (conversions and cross-overs) tend to occur in tight clusters, so that conversion within the gene has a high probability (apparently about 25 per cent in am) of being accompanied by an independently initiated cross-over close by and on either side more or less indiscriminately.
Article PDF
References
Catcheside, D G. 1968. The control of genetic recombination in Neurospora crassa. In Replication and Recombination of the Genetic Material (eds. W. J. Peacock and R. D. Brock). Austr. Acad. Sci., Canberra.
Chovnick, A, Ballantyne, G H, and Holm, D G. 1971. Studies on gene conversion and its relationship to linked exchange in Drosophila melanogaster. Genetics, 69, 179–209.
Fincham, J R S. 1967. Recombination within the am gene of Neurospora crassa. Genet Res, Camb, 9, 49–62.
Fincham, J R S, and Holliday, R. 1970. An explanation of fine structure map expansion in terms of excision repair. Molec Gen Genetics, 109, 309–322.
Fincham, J R S, and Day, P R. 1971. Fungal Genetics, pp. 402. Blackwell Scientific Publ., Oxford (see esp. Chapter 8).
Holliday, R. 1968. Genetic recombination in fungi. In Replication and Recombination of the Genetic Material (eds. W.J. Peacock and R. D. Brock). Austr. Acad. Sci., Canberra.
Hurst, D D, Fogel, S, and Mortimer, R K. 1972. Conversion-associated recombination in yeast. Proc Nat Acad Sci, 69, 101–105.
Murray, N E. 1963. Polarized recombination and fine structure within the me-2 gene of Neurospora crassa. Genetics, 48, 1163–1184.
Pritchard, R H. 1960. Localized negative interference and its bearing on models of gene recombination. Genet Res, Camb, 1, 1–24.
Smith, B R. 1965. Interallelic recombination at the histidine-5 locus in Neurospora crassa. Heredity, 20, 257–276.
Smyth, D R. 1971. Effect of rec-3 on polarity of recombination in the amination-1 locus of Neurospora crassa. Austr J Biol Sci, 24, 97–106.
Smyth, D R. 1973. A new map of the amination-1 locus of Neurospora crassa, and the effect of the recombination-3 gene. Austr J Biol Sci, 26, 1355–1370.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Fincham, J. Negative interference and the use of flanking markers in fine-structure mapping in fungi. Heredity 33, 116–121 (1974). https://doi.org/10.1038/hdy.1974.75
Received:
Issue date:
DOI: https://doi.org/10.1038/hdy.1974.75
This article is cited by
-
The orientation of gene maps by recombination of flanking markers for the am locus of Neurospora crassa
Current Genetics (1995)
-
Relationship of vector insert size to homologous integration during transformation of Neurospora crassa with the cloned am (GDH) gene
Molecular and General Genetics MGG (1990)
-
Gene conversions and crossing-over
Nature (1984)
-
Further evidence that aberrant segragation and crossing over in sordaria brevicollis may be discrete, though associated, events
Molecular and General Genetics MGG (1983)
-
Recombination in the am gene of Neurospora crassa—A new model for conversion polarity and an explanation for a marker effect
Heredity (1976)
