Enhanced gene conversion and postmeiotic segregation in pachytene-arrested Saccharomyces cerevisiae.
Enhanced gene conversion and postmeiotic segregation in pachytene-arrested Saccharomyces cerevisiae.
复制标题
粗线期捕获的酿酒酵母中增强的基因转换和减数分裂后分离。
DOI：
10.1093/genetics/106.2.165
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发表时间：
1984
期刊：
影响因子：
3.3
通讯作者：
Byers,B
中科院分区：
文献类型：
--
作者：
Davidow,LS;Byers,B
以前的研究表明，在孢子形成培养基中36 ℃下培养AP-1菌株的酵母细胞，可以使它们开始减数分裂，但它们在粗线期停止，并在2个异等位基因之间进行增强的基因内重组。进行四分体分析，以更广泛地表征减数分裂重组的改变程序。在一组实验中，在转移到允许温度时，允许被粗面素捕获的细胞恢复孢子形成。在由此产生的子囊，减数分裂后分离和基因转换增加了几倍，在一些位点相对于未逮捕的控制，而相互重组增加了两到三倍。另一组实验分析了诱导被粗面素阻滞的细胞在没有完成减数分裂的情况下直接恢复到有丝分裂生长的遗传后果。从杂合标记的纯合部门的外观显示，这些细胞已成为致力于可观的重组，但相互交流是不太频繁的比正常的asci。两者合计，数据表明，粗线期阻滞使细胞致力于增强重组后，恢复孢子形成，但大部分的交叉没有发生，直到释放的逮捕。- 通过将AP-1的每个亲本与能够在36°下形成孢子的菌株Y55的后代交配来研究AP-1的粗线期阻滞的遗传基础。这两个二倍体都在36°产孢，并且所研究的一个进一步显示出孢子形成缺陷的2：2分离，表明粗线期停滞依赖于染色体位点上的隐性温度敏感等位基因。
Previous study has demonstrated that incubation of yeast cells of strain AP-1 in sporulation medium at 36° permits them to begin meiosis but that they become arrested at pachytene and undergo enhanced intragenic recombination betweenade2heteroalleles. Tetrad analysis was undertaken to characterize the altered program of meiotic recombination more widely. In one set of experiments, pachytene-arrested cells were permitted to resume sporulation upon transfer to the permissive temperature. In the resulting asci, both postmeiotic segregation and gene conversion were increased several-fold at a number of loci relative to unarrested controls, whereas reciprocal recombination increased two- to threefold. Another set of experiments analyzed the genetic consequences of inducing the pachytene-arrested cells to revert directly to mitotic growth without completion of meiosis. The appearance of homozygous sectors from heterozygous markers revealed that these cells had become committed to appreciable recombination but that reciprocal exchange was less frequent than in normal asci. Taken together, the data indicate that pachytene arrest rendered the cells committed to enhanced recombination upon resumption of sporulation but that most of the crossing over did not occur until release from the arrest. —The genetic basis of pachytene arrest by AP-1 was investigated by mating each of its parents with progeny of strain Y55, which is able to sporulate at 36°. Both of these diploids sporulated at 36°, and asci from the one studied further exhibited 2:2 segregation of the sporulation defect, indicating that pachytene arrest is dependent on a recessive, temperature-sensitive allele at a chromosomal locus.