SELECTION FOR TRISOMIC CELLS IN A MOSAIC FIBROBLAST CULTURE

In a human mosaic fibroblast culture consisting of a diploid cell line, 46, XY, t(Cp+;Dq-), and a trisomic cell line, 47, XY, D4-, t(Cp +;Dq-), the frequency of trisomic cells initially decreased from 74% to 48% and then increased steadily through successive passages, until finally all diploid cells disappeared. The gradual predominance of trisomic cells coincided with the degenerative phase of the culture. It is speculated that although the genetically balanced diploid cells competed well in the beginning, they started their senescence earlier, thus giving way to the genetically unbalanced trisomic cells. Perhaps the same selective advantage of aneuploid cells over diploid cells could be shown in other mosaic cell cultures if they are maintained for longer periods. © 1969 S. Karger AG, Basel.