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Double reversal of gene conversion polarity and multiple conversion events in the locus “14” in Podospora anserina

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The present study deals with conversion analysis within the polycistronic unit of transcription of locus “14” in Podospora anserina. Data from 74 two-point crosses involving 33 different mutants are in favour of a conversion polarity exhibiting two reversals (Fig. 1a, b), one being entirely located within the distal cistron. This pattern of polarized recombination suggests the existence of an intracistronic recombinational discontinuity.

Two, three, four and five-point (within the polycistronic unit) crosses allow to draw several conclusions concerning the conversion event:

it involves a continuous chromosomal segment;

it can take place in two or several sites belonging to the same cistron or to different contiguous cistrons;

it can overlap the region corresponding to the postulated discontinuity;

its maximum dimension is smaller than that of the polycistronic unit.

Many two-point crosses give double-site conversions occurring as two separate but correlated events, and involving two homologous chromatids (non associated conversions). The frequency of such recombination events is lower than that of a simultaneous conversion.

All these results are briefly discussed in terms of different recombination models.

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Communicated by W. Gajewski

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Touré, B. Double reversal of gene conversion polarity and multiple conversion events in the locus “14” in Podospora anserina . Molec. Gen. Genet. 117, 267–280 (1972). https://doi.org/10.1007/BF00271653

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  • Recombination
  • Recombination Event
  • Gene Conversion
  • Correlate Event
  • Chromosomal Segment