Chromosome analysis of a simian virus 40-transformed mouse cell line and two variant sublines that are resistant to cytochalasin B1.

The chromosomes of an SV40-transformed mouse cell line, SVT2, were analyzed by the acetic-saline-Giemsa banding technique. By contrast to most established mouse lines, SVT2 cells possess a remarkably homogeneous chromosome complement and contain two copies of most chromosomes. However, trisomy for chromosome 3 is a distinct feature of this cell line. Chromosomes 1, 3, 14, and 19 have given rise to biarmed markers. Two Cytochalasin B-resistant sublines derived from SVT2 are also essentially diploid for all autosomes but contain only one chromosome X; they display an even greater homogeneity than does the SVT2 parental cell line. Each of the Cytochalasin B-resistant cell lines has lost one or several of the biarmed markers from SVT2 and new ones have appeared. Both cell lines have lost one copy of chromosome 3 and one chromosome X. The results presented illustrate the advantages of cells of defined chromosome constitution, like STV2 cells and derived sublines, to study specific interactions between transforming virus and host chromosomes. The possible role of SV40 in the maintenance of the pseudodiploid karyotype of SVT2 is also discussed.