DNA-mediated gene transfer of beta-aspartylhydroxamate resistance into Chinese hamster ovary cells.

Cell lines that have high levels of resistance to beta-aspartylhydroxamate and elevated levels of asparagine synthetase activity were selected in two steps from Chinese hamster ovary cells. Resistance to beta-aspartylhydroxmate was transferred into sensitive cells by using total genomic DNA derived from the dominant two-step mutants. The surviving colonies were characterized as transferants on the basis of transfer frequency, degree of resistance to beta-aspartylhydroxamate, increased level of asparagine synthetase activity, expression of the donor form of asparagine synthetase, codominance in hybrids, and instability of the phenotype in the absence of selection.