Sister chromatid exchange in FR3T3 rat fibroblasts transformed by simian virus 40

Abstract The frequency of Sister Chromatid Exchange (SCE) was determined at low (33 °C) and high (40.5 °C) temperatures in cell lines derived from FR3T3 rat fibroblast cells after transformation either with Wild-Type Simian Virus 40 (SV40-WT), with an origin-defective SV40 (SV40-ori − ), or with the early temperature-sensitive mutant tsA 30. Of these cell lines, SV40-WT-, SV40-ori − -, and one class of tsA 430-transformants (A-type) express the transformed phenotype both at 33 and 40.5 °C. The other tsA 30-transformants (N-type) revert to a normal phenotype at high temperature. As compared with normal FR3T3 cells, all transformants exhibited, at 33 °C, increased numbers of metaphases with high SCE rates. At 40.5 °C, all cell lines which expressed a transformed phenotype (SV40-WT, tsA 30 type A, SV40-ori − ) exhibited substantially increased SCE rates. That this increase was not related to a possible induction of viral replication by BrdU, was proven by Southern blot analysis and by SCE data on SV40-ori − -transformed cells. By contrast, no such temperature-induced increase of SCE rates was observed in tsA 30-transformants of type N.