A new dominant hybrid selective marker for higher eukaryotic cells

A new dominant hybrid genetic marker, suitable for selection in higher eukaryotic cells, has been obtained by linking the promoter region of the Herpes simplex virus type I thymidine kinase gene to the gene coding for the aminoglycoside 3′ phosphotransferase coded for by the Tn5 transposon. As described for yeasts (Jimenez &; Davies, 1980), the expression of the enzyme allows the formation of cellular clones resistant to the antibiotic G-418, which is otherwise toxic to the cells. This dominant marker was expressed in all cell lines tested (human, simian and murine). The construction of the hybrid gene has been optimized and, for a given construction, transformation efficiency depends on the cell line. We also report that an unlinked gene can be cotransferred into cells with the marker and be expressed at high frequency.