Defective post-replication recovery and u.v. sensitivity in a simian virus 40-transformed Indian muntjac cell line

The responses to u.v. of two cell lines derived from the Indian muntjac are described. The u.v. sensitivity of the diploid cell falls within the range of most normal mammalian cells while the other, a heteroploid cell, transformed by SV40, is much more sensitive to killing. This hypersensitivity cannot be explained by defective excision repair: the two cell types are indistinguishable in this activity as judged by inhibitor-associated DNA break accumulation and unscheduled DNA synthesis. Rather, the SV40 transformed cells have a pronounced inability to recover normal DNA replication after u.v. These cells are, therefore, defective in a post-replication recovery mechanism and in this respect resemble the behaviour of the variant form of xeroderma pigmentosum. Their limited ability to recover normal levels of RNA synthesis after u.v. hints at the complexity of the phenotype.