Polarized negative interference in the<i>paba 1</i>region of<i>Aspergillus nidulans</i>

Abstract

The intensity of negative interference in 28 crosses involving 14 allelic paba mutants in different combinations has been measured. Among selected cross-overs between two such mutants, when the distance between the mutants is large, additional exchanges on the distal side (relative to the centromere) greatly exceed those on the proximal side. With decreasing length of the interval of selection, the inequality disappears. It is suggested that this polarity may be the outcome of a undirectional process which imposes a time sequence on the recombination events within an effectively paired segment. Some alternative explanations of this result are discussed.