Assignment of TK1 encoding thymidine kinase to Syrian hamster chromosome 9 by microcell-mediated chromosome transfer

We report here the assignment of TK1, the gene for thymidine kinase to Syrian hamster (Mesocricetus auratus) chromosome 9 (MAU9) by complementation mapping. Syrian hamster chromosomes derived from a wild type (TK+) subline of BHK cells were introduced via microcell-mediated chromosome transfer into B82 mouse cells deficient in thymidine kinase (TK-), a defect that prevents their growth in HAT culture media. Hybrid clones were selected in HAT media. Chromosome analyses of the microcell hybrids showed that the thymidine kinase deficiency of B82 cells was corrected by MAU9. Therefore, we assigned TK1 to MAU9. Previously, TK1 was assigned to mouse chromosome 11 (MMU11), rat chromosome 10 (RNO10), Chinese hamster chromosome 7 (CGR7), and human chromosome 17 (HSA17). The striking banding homology of MAU9 with RNO10, MMU11, CGR7 and HSA17 provides additional support for the assignment of TK1 to MAU9. To our knowledge, this is the first report of gene assignment to a specific Syrian hamster chromosome using the somatic cell hybridization technique.