Pretorius I S, Marmur J
Department of Microbiology, University of Stellenbosch, South Africa.
Curr Genet. 1988 Jul;14(1):9-13. doi: 10.1007/BF00405847.
Chromosomes of two closely related yeast strains, the amylolytic Saccharomyces diastaticus and the non-amylolytic Saccharomyces cerevisiae, were resolved by pulsed field gel electrophoresis (PFGE) and orthological field alteration gel electrophoresis (OFAGE). Electrophoretic karyotypes of these two strains are identical. Sixteen cloned Saccharomyces genes of known chromosomal location were used to identify individual chromosomes by Southern hybridization analyses. The Southern blots were reprobed with a cloned fragment of the STA2 glucoamylase gene of S. diastaticus. STA2 exhibits homology to STA1 and STA3 as well as the sporulation-specific glucoamylase (SGA) gene from both Saccharomyces strains. The three unlinked, homologous genes, STA1 (DEX2, MAL5), STA2 (DEX1) and STA3 (DEX3) encoding the extracellular glucoamylase isozymes GAI, GAII and GAIII in S. diastaticus were then assigned to chromosomes IV, II and XIV, respectively. The SGA gene, encoding an intracellular glucoamylase in both S. diastaticus and S. cerevisiae, was assigned to chromosome IX. Electrophoretic mapping of the STA and SGA genes is at present the only way to localize these genes, since glucoamylase repressor gene(s) (STA10, INH1 and/or IST2) are present in most laboratory strains of S. cerevisiae and the SGA phenotype is only detectable during sporulation.
通过脉冲场凝胶电泳（PFGE）和正交场交变凝胶电泳（OFAGE）解析了两种亲缘关系密切的酵母菌株——产淀粉酶的糖化酵母（Saccharomyces diastaticus）和不产淀粉酶的酿酒酵母（Saccharomyces cerevisiae）的染色体。这两种菌株的电泳核型是相同的。利用16个已知染色体定位的克隆酿酒酵母基因，通过Southern杂交分析来鉴定各个染色体。用糖化酵母STA2葡糖淀粉酶基因的克隆片段对Southern杂交印迹进行再次杂交。STA2与STA1、STA3以及两种酿酒酵母菌株的孢子形成特异性葡糖淀粉酶（SGA）基因具有同源性。在糖化酵母中，编码胞外葡糖淀粉酶同工酶GAI、GAII和GAIII的三个不连锁的同源基因STA1（DEX2、MAL5）、STA2（DEX1）和STA3（DEX3）分别被定位到染色体IV、II和XIV上。在糖化酵母和酿酒酵母中编码胞内葡糖淀粉酶的SGA基因被定位到染色体IX上。目前，STA和SGA基因的电泳图谱是定位这些基因的唯一方法，因为大多数酿酒酵母实验室菌株中都存在葡糖淀粉酶阻遏基因（STA10、INH1和/或IST2），并且SGA表型仅在孢子形成过程中可检测到。
