Dorothy M. Spencer

Transformation of Yeast: Saccharomyces cerevisiae

Transformation of yeast with foreign DNA can be achieved by the use of two different techniques. The first depends on the complete (or partial) proto-plasting of yeast cells to allow uptake of the foreign DNA (Hinnen et al. 1978). The second uses intact cells treated with lithium acetate to promote DNA uptake (Ito et al. 1983). The method that yields the best frequency of transformation is strain dependent and also depends upon the nature of the transforming DNA involved. Wide variations among strains in their efficiency of transformation have been observed; e.g. Johnston et al. (1981).

Plasmid Isolation from Yeast

The method by which plasmids can be isolated from yeast or any other cells depends upon; (a) the volume of culture involved, (b) the purity of the DNA which is ultimately required; i.e. the use to which it will eventually be put, (c) how quickly the plasmid is required, and (d) the size of the plasmid.

Rapid Isolation of DNA from Yeast

The method of Devenish and Newlon (1982) allows rapid, efficient isolation of yeast plasmid DNA. However, it does not aUow the recovery of high-molecular-weight DNA. On occasion it is useful to be able to obtain relatively small quantities of high-molecular-weight DNA rapidly for restriction analysis, Southern blotting, transformation etc. In such instances, it is laborious and time-consuming to follow the procedure given previously (p. 84). The method described below provides an alternative (Holm et al. 1986).