DNA synthesis and multinucleation of mouse cells infected with SV40 in the presence of cytochalasin B.

DNA synthesis and nuclear division of mouse cells, BALB/3T3, infected with SV40 were studied and were compared with those of SV40-transformed mouse cells, mKS-A TU-7. Both SV40-infected and SV40-transformed cells behaved similarly in the presence of cytochalasin B and differently from normal noninfected cells, BALB/3T3. The chemical inhibited cytokinesis of all the cell groups but the nuclear division was inhibited only in the case of non-infected BALB/3T3. With SV40-infected BALB/3T3, multinucleation occurred with the increase of input m.o.i. by SV40. SV40-infected BALB/3T3 could enter the second S phase after release from double thymidine block in the presence of cytochalasin B, while BALB/3T3 could not enter the second S phase. In bi- or multinucleated cells of SV40-infected BALB/3T3, asynchrony of DNA synthesis among nuclei in a cell was evident, as was the case with mKS-A TU-7.