[Mutations affecting intrachromosomal recombination and conversion in the binary y(2ns)sc(me) system in Drosophila melanogaster].

The effect of mutations in various genes whose products are involved in chromosome organization on the mutagenesis in a double superunstable y2nsscme system was studied. Among these mutations were those in loci zeste, e(y) e(y) 1,2 and 3, responsible for long-distance interactions in chromosomes, and those in the loci E(z), Su(z), Scm, and Psc, whose protein products take part in chromatin compaction. Many of the mutations studied markedly affect the spectrum and the frequency of mutations in the system, in particular, the frequency of double events. The results suggest that the spatial organization of chromosomal domains plays a role in intrachromosomal recombination and gene conversion, since these processes were shown earlier to be dominant in the mutagenesis of a double superunstable system. Some of the mutations under study also modify the phenotypic manifestation of the y2nsscme allele.