Co-transfer of human X-linked markers into murine somatic cells via isolated metaphase chromosomes

Transformation frequencies of 4 x 10(-5) were obtained in chromosome-mediated gene transfer experiments using human cell line HeLa S3 as donor and mouse cell line A9 as recipient. This high frequency of interspecific transformation was achieved by treating the recipient cells with dimethylsulfoxide in addition to other facilitators. The high frequency of transformation correlated positively with transgenome size on the basis of both co-transfer of linked markers and chromosome analysis. The syntenic human markers glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP(+) 1-oxidoreductase, EC 1.1.1.49) and phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) were sometimes transferred together with the selected X-linked prototrophic marker hypoxanthine phosphoribosyltransferase (IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) into murine somatic cells. Donor human chromosome material could be demonstrated cytologically in some of the transformed cell lines. Transformants exhibited various rates of loss of the human hypoxanthine phosphoribosyltransferase marker when grown under nonselective conditions. These results reveal a broader range of possible interspecific transgenome sizes than has been recognized in the past. The largest transgenomes consist of cytologically detectable donor fragments and contain syntenic markers that are not closely linked to the selected marker.