[Chromosome variability in established cultures of Drosophila melanogaster embryonal cells]

Diploid cell lines with female karyotype for 7 years conserved the normal chromosome set. Tripoid and tetraploid chromosome sets also remained unchanged after two years of cultivation in both sublines. The karyotypes characterized by supernumerary X-chromosomes or deficient for one or more X-chromosomes are predominant among the aneuploids in diploid and euploid lines. The cloning technique allows to isolate the hyperploid variants only. The following karotypic changes were observed during prolonged cultivation: a loss of a single chromosome from the 4th pair; the X-autosome (third pair) translocation; the enlargement of a heterochromatic pricentromeric segment of the X-chromosome; the centric fusion of the X-chromosomes. The formation of 2 telocentric fragments as a result of the centromeric breakage of the autosome of the second pair is a typical chromosome aberration observed in diploid, triploid and tetraploid cell lines.