Summary
One hundred and eight single or multi-point crosses involving frameshift mutants in the A group of intragenic suppression were analysed. The frequencies of coconversion were always very high ( > 0·94). Two parameters were considered: the frequency of conversion and the disparity values of conversion (i.e. the ratio of 6 + : 2m to 2 + : 6m asci). The pattern of variation of the disparity values agrees with an equal influence of the associated heterozygous sites in determining the direction of conversion.
This suggests that the excision process needed for heteroduplex correction proceeds in both directions from the one stranded nick provoked by the mismatch, i.e. that there is no important excision polarity. It also suggests that recognition of the mismatch prior to nicking is not part of a polar process.
The positive correlation observed between the disparity value and the frequency of conversion is considered as new evidence for frequent symmetrical distribution of hybrid DNA in the region studied.
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Leblon, G., Rossignol, JL. The interaction during recombination between closely linked allelic frameshift mutant sites in Ascobolus immersus. Heredity 42, 337–352 (1979). https://doi.org/10.1038/hdy.1979.37
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DOI: https://doi.org/10.1038/hdy.1979.37
