Srivastava P K, Harashima S, Oshima Y
Mol Gen Genet. 1983;191(1):165-6. doi: 10.1007/BF00330906.
Genetical analysis of two-spored asci formed by interrupted sporulation offers a novel procedure for mapping of centromere-linked genes in Saccharomyces cerevisiae. Unlike the two-spored asci encountered under normal sporulation conditions, these asci are produced by a nonrandom mechanism. They fall into three categories (+ +), (+ -) and (- -) with respect to any marker. The percentage of (+ -) asci varies directly as a function of centromere-linkage of a gene. It is observed that almost 100% asci are of the (+ -) type in case of very tightly linked genes like trp-1 and cdc-10, while in case of markers unlinked to the centromere, e.g, trp-5 and met-8, the (+ -) asci constitute 50% of the total number of asci. Other markers with varying degrees of linkage, e.g. ura-3 and lys-1 show corresponding numbers of (+ -) asci between 50% and 100% of the total asci. These findings are in contrast to the results expected from a random abortion of two spores, in which case the (+ -) asci would constitute 67% of the total number of asci irrespective of the degree of centromere linkage of a marker. The linkage-dependent segregation of markers in these new kind of two-spored asci permits a rapid and accurate estimate of centromere linkage of a gene.
通过中断孢子形成产生的双孢子子囊的遗传分析为酿酒酵母中着丝粒连锁基因的定位提供了一种新方法。与正常孢子形成条件下遇到的双孢子子囊不同，这些子囊是由一种非随机机制产生的。就任何标记而言，它们可分为三类（++）、（+-）和（--）。（+-）子囊的百分比直接随基因的着丝粒连锁而变化。据观察，对于像trp-1和cdc-10这样紧密连锁的基因，几乎100%的子囊是（+-）型，而对于与着丝粒不连锁的标记，例如trp-5和met-8，（+-）子囊占子囊总数的50%。其他具有不同连锁程度的标记，例如ura-3和lys-1，显示出相应数量的（+-）子囊，占总子囊数的50%至100%。这些发现与两个孢子随机败育预期的结果形成对比，在随机败育的情况下，无论标记的着丝粒连锁程度如何，（+-）子囊都将占子囊总数的67%。在这些新型双孢子子囊中，标记的连锁依赖性分离允许快速准确地估计基因的着丝粒连锁。
