THE MECHANISM OF CHROMOSOME LOSS AFTER MA TURE SPERM IRRADIATION

The frequency of radiation-induced chromosome losses is not connected with heterochromatic content but depends on the total chromosomal DNA content. This dependence is of the selective nature and appears as a r esult of the effect of dominant letality of non-repaired euchromatic b reaks. Simultaneous losses of the two chromosomes in one nucleus are n ot independent, because of the interaction of the heterochromatic brea ks underlying these losses. The conclusion is made that the chromosome losses are involved in the exchange events accompanied by the centrom ere deletion.