Specific karyotypic alterations in colchicine-resistant cells.
Djungarian hamster and mouse L-53 cell lines with 150--200-fold increases in resistance to colchicine contained marker chromosomes with a long homogeneously staining region (HSR). In two clones of Djungarian hamster cells, an HSR was located in the long arm of chromosome 4; in another Djungarian hamster cell line and in mouse L-53 cells, and HSR was located in unidentified marker chromosomes. During cultivation in colchicine free medium these cells lost their resistance at the rate of 2--3 x 10(-2) cells per population doubling. The loss of resistance was accompanied by the disappearance of the HSR and emergence of possible double minutes (dmins). These observations suggest that colchicine-resistance is the result of gene amplification and support the idea that dmins may be derived from the HSR in these systems.
D000818:Animals; D002460:Cell Line; D002875:Chromosomes / Q000648:ultrastructure*; D002999:Clone Cells; D003078:Colchicine / Q000494:pharmacology*; D006224:Cricetinae; D003470:Culture Media; D004351:Drug Resistance; D005784:Gene Amplification; D007621:Karyotyping; D051379:Mice
D003470:Culture Media; D003078:Colchicine