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Time-dependent changes in gene conversion in Ascobolus immersus

Published online by Cambridge University Press:  14 April 2009

Shacker Helmi  and
Bernard C. Lamb
Shacker Helmi
Affiliation:
Department of Biology, Imperial College, London SW7 2BB
Bernard C. Lamb
Affiliation:
Department of Biology, Imperial College, London SW7 2BB
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The stability of conversion frequencies with time was investigated in Ascobolus immersus. There were usually marked reductions in gene conversion frequencies at locus wl as crosses matured, to about one third of the initial values. This applied to all six wl alleles tested, irrespective of their molecular nature, and at all temperatures used. Asci dehiscing early from an apothecium had much higher conversion frequencies than those dehiscing late, but there were no differences between apothecia maturing at different times within a cross. Alleles at four loci unlinked to wl were also tested. All four showed significant changes, though not in all crosses; three loci showed decreases in conversion frequency with time, while one showed an increase. The relative frequencies of different conversion classes often changed with time. These changes appear to result from alterations in locus-specific recombination initiation and in repair of base mispairs in hybrid DNA, not from differential maturation rates of different ascal segregation classes. These effects could cause misinterpretation of quantitative tests of recombination models from gene conversion data.

Type
Research Article
Information
Genetics Research , Volume 57 , Issue 2 , April 1991 , pp. 97 - 103
Copyright
Copyright © Cambridge University Press 1991

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