INTRA-CHROMOSOMAL DISTRIBUTION PATTERNS OF MUTAGEN-INDUCED SCES AND CHROMATID ABERRATIONS IN RECONSTRUCTED KARYOTYPES OF VICIA-FABA

The FPG (fluorescent plus Giemsa) technique was used in a study of the frequency and the inter- and intra-chromosomal distribution patterns of SCEs after incorporation of BrdUrd into the chromosomal DNA as well as after additional mutagen treatment in two reconstructed karyotypes of Vicia faba. The kartotypes used orginated from combining of different translocations and pericentric inversions (each homozygously) and allowed the exact morphological phological identification of each of the 6 chromosome pairs. Treatment with ethanol (EA), maleic hydrazide (MH) and mitomycin C (MMC) resulted in a strong increase of SCE frequency. With one exception (the nucleolus-organizing secondary constriction) the inter- and intra-chromosomal distribution of SCEs was length proportional, independently of whether or not additional mutagen treatment was performed. This indicates absemce of coincidence between the intra-chromosomal distribution patterns of mutagen-induced SCEs an chromatid aberrations for the following reasons: (1) chromatid aberrations have been shown to be non-randomly and, in part at least, mutagen-specifically distributed; (2) chromosome segments, which were found to be differently involved in chromatid aberrations when differently positiones in the two karyotypes, were equally involved in mitomycin-C-induced SCEs. The results are discussed with respect to possible connections between the mechanisms leading to SCEs and to chromatid aberrations. © 1979.