ON DISTRIBUTION BETWEEN CHROMOSOMES OF CHEMICALLY INDUCED CHROMATID ABERRATIONS - STUDIES WITH A NEW KARYOTYPE OF VICIA FABA

A new karyotype of Vicia faba with all 12 chromosomes easily interdistinguishable has been used to study the interchromodomal distribution of chromatid aberrations induced by ethyl alcohol and maleic hydrazied. The distribution patterns of intra- and interchanges induced by ethyl alcohol and maleic hydrazide are non-random and agent-specifc. These patterns are neither changed by pretreatment with EDTA which sensitizes the cells to both agents nor by scoring aberrations after different recovery times. The preferential participation in aberrations of individual chromosome segments which is responsible for the non-random and agent-specific distribution of aberrations between chromosomes is a transposable feature of the segments in question. The transfer of such a segment to another position within the karyotype is accompanied by a corresponding shift in aberration distribution. In addition to ethyl alcohol- and maleic hydrazide-specific patterns of distribution of chromatid aberrations, particular chromosomes and chromosome segments have been found to be involved with differing frequencies in particular types of aberration after both ethyl alcohol and maleic hydrazide treatment. This is understood as being due to factors which, secondarily and differentially, influence the type of interaction of lesions preferentially induced in the relevant chromosomes and chromosome segments. © 1968.