P93-50, a 93-basepair (bp) repetitive DNA sequence from rats, was hybr
idized to transformed sublines of rot endothelial origin. The sequence
hybridized at or near the centromeres of most but not all chromosomes
in two transformed cell lines and three single-cell derived cultures.
The hybridization signal was also frequently present at the telomeres
. These cell lines have a highly aberrant karyotype including dicentri
c and multicentric chromosomes; however, even though this sequence lab
eled the centromere regions of some chromosomes, it did nor hybridize
with the telomere regions of the cell line XC, which rarely shows any
dicentrics. Apparently, the telomere signals represent prematurely sep
arating, inactive, terminal centromeres. The p93-50 sequence does nor
influence the timing of centromere separation, nor it is necessary for
formation of heterochromatin.