Thymidylate synthase-deficient Chinese hamster cells: a selection system for human chromosome 18 and experimental system for the study of thymidylate synthase regulation and fragile X expression.

摘要: Chinese hamster lung (CHL) V79 cells already deficient in hypoxanthine phosphoribosyltransferase were exposed to uv light and selected for mutations causing deficiency of thymidylate synthase (TS) by their resistance aminopterin the presence thymidine limiting amounts methyl tetrahydrofolate. Three seven colonies chosen initial study shown be (TS-) enzyme assay, auxotrophy, inability incorporate labeled deoxyuridine into DNA vivo. Complementation analysis human X TS- hybrids revealed that TS activity segregated with chromosome 18. Southern a panel 14 probed complementary from mouse confirmed assignment 18; quantitative blotting using unbalanced cell lines further localized gene 18q21.31----qter. Another hybrid was generated contained Xq28 folate-dependent fragile site as its only background. The could easily reproducibly expressed this without use antimetabolites simply removing exogenous medium. These TS-deficient are useful for: somatic genetics unique selectable marker 18, studies on regulation gene, (X) other sites.