[Cytogenetic analysis of recombination interactions]

Chiasma interference between separate regions of chromosomes was studied in three phylogenetically distant species. All these species displayed the similar patterns of chiasma interference. Chiasma completely suppressed recombination in the regions next to chiasma within a chromosome's arm. The level of crossing-over suppression decreased non-linearly with increase in a distance between the chiasma and the region under analysis. Some kind of the threshold effect was observed. In some cases, negative interference between the regions rather remote from each other was noted. Polarity of interference was revealed: interstitial chiasma suppressed recombination in the proximal (in relation to the centromere) direction more effectively than in the distal direction. Some regions belonging to the different arms of the same chromosome were shown to be able to interfere.