Embryonic stem cells can be used to construct hybrid cell lines containinga single, selectable murine chromosome

Microcell-mediated chromosome transfer is a useful technique for the study of gene function, gene regulation, gene mapping, and functional cloning in mammalian cells. Complete panels of donor cell lines, each containing a dif ferent human chromosome, have been developed. These donor cell lines contai n a single human chromosome marked with a dominant selectable gene in a rod ent cell background. However, a similar panel does not exist for murine chr omosomes. To produce mouse monochromosomal donor hybrids, we have utilized embryonic stem (ES) cells with targeted gene disruptions of known chromosom al location as starting material. ES cells with mutations in aprt, fyn, and myc were utilized to generate monochromosomal hybrids with neomycin phosph otransferase-marked murine Chr 8, 10, or 15 respectively in a hamster or ra t background. This same methodology can be used to generate a complete pane l of marked mouse chromosomes for somatic cell genetic experimentaion.