Abstract
SUMMARY: Double cross-overs were detected in a few crosses involving segment ‘29’ mutants of locus ‘14’ in Podospora anserina. The occurrence of such recombination events made it necessary to reconsider the localization of three mutants. Use of an outside marker and the analysis of many other crosses allowed these mutants to be mapped unambiguously. The change in the localization of one of these mutants together with complementation tests on a new mutant leads to the conclusion that the polycistronic unit of transcription contains only four cistrons instead of the five previously thought to exist.