Abstract
Chromosome-mediated gene transfer (CMGT) can be used to generate fragments of human chromosomes and chromosomal maps can be constructed using these fragments. In previous experiments CMGT techniques have been limited to those regions of the genome which encode biochemically selectable markers. We have extended the regions of the human genome which can be subjected to CMGT methods by employing a cell surface antigen as a selectable marker. These experiments have been facilitated by the discovery that co-transformation of chromosomes with a plasmid bearing a biochemically selectable marker followed by selection for the marker pre-selects for cells which have incorporated chromosomal fragments. The plasmid may also integrate into the donor chromosomes and this provides, in some cases, an additional selectable marker in the chromosome fragment of interest. Using these methods we have isolated for the first time cells containing varying portions of the human Y chromosome.