Transfer of antibiotic resistance genes between yeast and mammalian cells under conditions favoring cell fusion

Antibiotic resistance to G418 has been transferred into Chinese hamster cell lines via a plasmid vector. The same plasmid, which also contained the Leu2 gene, has been used to transform Leu2^- yeast (strain MCI6) to leucine prototrophy. Subsequent fusion between transformed yeast and untransformed hamster cells demonstrated that plasmid DNA could be transferred and its genes expressed within the mammalian cell genome. The fusion of transformed hamster cells with untransformed MC16 yeast cells demonstrated that DNA integrated within the mammalian cell genome could be transferred to correct the Leu2 deficiency and also confer G418 resistance on some yeast colonies.