Chemical transformation of Chinese hamster cells: II. Appearance of marker chromosomes in transformed cells.

The chromosomes of 12 samples of cultured Chinese hamster kidney and prostate cells (4 normal and 8 transformed), whose tissue culture properties have already been described (Kirkland, 1976) have been examined for numerical change and for the appearance of abnormal markers. Six transformed kidney subclones contained a consistent telocentric marker not present in the normal parental cell, and Giemsa banding demonstrated this to be the centromere and the long (q) arm of the number 4 chromosome in all cases. Two transformed prostate subclones also contained a consistent telocentric marker, not present in similarly derived normal subclones or in the normal parental cell, and Giemsa banding demonstrated this to be a different fragment (the centromere and most of the p arm) of the number 4 chromosome. It is believed that the use of a mixed-serum culture medium, designed to stabilize the karyotype of cultured Chinese hamster cells, is at least partly responsible for the detection of these transformation-associated chromosome changes.