INSTABILITY OF CHO CHROMOSOMES CONTAINING INTERSTITIAL TELOMERIC SEQUENCES ORIGINATING FROM CHINESE-HAMSTER CHROMOSOME-10

We identified a marker chromosome in the CHO K1 cell line containing a mplifications of interstitial telomeric sequences originating from Chi nese hamster chromosome 10. Analysis of the progression of this chromo some in two subclones of CHO K1 revealed sensitivity of one amplicon t o chromosome breakage, resulting in telomere function at the break sit e. In addition, two more marker chromosomes, both containing amplifica tions of interstitial telomeric sequences from chromosome 10, were for med during karyotypic evolution of the CHO K1 subclones. The presence of some of the marker chromosomes was also identified in the radiosens itive xrs 5 cell line derived from CHO K1. These results indicate inst ability of CHO K1 chromosomes containing interstitial telomeric sequen ces originating from Chinese hamster chromosome 10.