G418 SELECTION AND STABILITY OF CLONED GENES INTEGRATED AT CHROMOSOMAL DELTA-SEQUENCES OF SACCHAROMYCES-CEREVISIAE

The chromosomal delta sequences of the yeast Saccharomyces cerevisiae were employed as recombination sites to integrate the bacterial neo(r) gene and the yeast SUC2 gene into the yeast genome. A dominate select ion method employing the aminoglycoside antibiotic G418 was used. Tran sformation efficiencies and growth behaviors of the transformants were studied. Transformants were obtained with more than 40 integrations; the majority of insertions were tandem with a maximum of three differe nt insertion sites utilized at one time. After 70-100 generations of g rowth in nonselective medium, the high copy number SUC2-neo(r) integra nts were found to be unstable; only minor instability was observed for the neo(r) and low copy number SUC2-neo(r) integrants. (C) 1996 John Wiley & Sons, Inc.