Effect of gene dosage on tryptophan synthetase activity in Saccharomyces cerevisiae.

A direct relation between gene dosage and amount of the corresponding protein is generally assumed to exist though it has been investigated in a limited number of cases. Yeasts seem to be an ideal material for this type of investigation as they can be easily obtained in different degrees of ploidy. Macromolecular components of yeast cells in polyploid series have been already determined (OGUR et al. 1952) and the relationships between gene dosage and enzyme production have been analysed for galactokinase (NELSON and DOUGLAS 1963) and iso-lcytochrome (SJXNIMSKI et al. 1965). Data reported here will deal with the con-' struction of a polyploid series of Saccharomyces cerevisiae (haploid, diploids and tetraploids) , the determination of DNA and soluble protein content on a per cell basis, and the relation of tryptophan synthetase2 (TST) activity to ploidy and gene dosage.