Li C L, Li T S, Zhang M, Li J Z, Chen S Y
College of Life Science, Zhejiang University, Hangzhou.
Yi Chuan Xue Bao. 1999;26(6):731-7.
Diploid strains homozygous for both MAT allele and STA genes (a/a, STA1/STA1 or STA2/STA2 or STA3/STA3) and diploid strains homozygous for MAT allele but intercombinative for STA genes (a/a, STA1/STA2 or STA2/STA3 or STA1/STA3) were constructed by means of the protoplast fusion or the colchicine treatment. According to glucoamylase activity in YPS medium, we studied the gene-dosage effect and their interrelation of these three polymeric genes coding for glucoamylase. The results of the glucoamylase activity determination showed that the gene-dosage effect of glucoamylase is obvious in diploid and triploid strains homozygous for both MAT allele and STA gene, such as the glucoamylase activity of a diploid strain SFY56-6 and a triploid strain SFY56-104 homozygous for both MAT allele and STA genes were respectively 2.35 and 3.18-fold as compared with that of the their parental strain IATA-Y56 that is a haploid Saccharomyces diastaticus. Moreover, the glucoamylase activity of diploid strains homozygous for MAT allele but intercombinative for STA genes also showed the combinative gene-dosage effect to a certain extent.
通过原生质体融合或秋水仙碱处理构建了对 MAT 等位基因和 STA 基因均纯合的二倍体菌株（a/a，STA1/STA1 或 STA2/STA2 或 STA3/STA3）以及对 MAT 等位基因纯合但 STA 基因相互组合的二倍体菌株（a/a，STA1/STA2 或 STA2/STA3 或 STA1/STA3）。根据 YPS 培养基中的葡糖淀粉酶活性，我们研究了这三个编码葡糖淀粉酶的聚合基因的基因剂量效应及其相互关系。葡糖淀粉酶活性测定结果表明，在对 MAT 等位基因和 STA 基因均纯合的二倍体和三倍体菌株中，葡糖淀粉酶的基因剂量效应明显，例如，对 MAT 等位基因和 STA 基因均纯合的二倍体菌株 SFY56-6 和三倍体菌株 SFY56-104 的葡糖淀粉酶活性分别是其亲本菌株 IATA-Y56（一种单倍体糖化酵母）的 2.35 倍和 3.18 倍。此外，对 MAT 等位基因纯合但 STA 基因相互组合的二倍体菌株的葡糖淀粉酶活性在一定程度上也表现出组合基因剂量效应。
