Esposito M S
Symp Soc Exp Biol. 1984;38:123-59.
Recombination in the yeast Saccharomyces cerevisiae has been the subject of extensive genetic studies documenting the general properties of intragenic and intergenic recombination and the differences between mitotic and meiotic gene conversion and reciprocal exchange. Spontaneous mitotic and meiotic events differ in the time of onset of recombination relative to chromosomal replication, symmetry versus asymmetry of putative heteroduplex DNA regions, polarity of conversion of intragenic markers, and the lengths of DNA segments that undergo coincident conversion. The differences observed and the properties of yeast rec mutations provide evidence for multiple modes or pathways of mitotic and meiotic recombination. Several molecular models of recombination have been proposed to account for the basic parameters of genetic recombination and the differences between mitotic and meiotic recombination. Since the models differ with respect to the partial reactions comprising recombination they predict the isolation of different classes of hypo-recombination and hyper-recombination rec mutants. We have isolated a broad spectrum of yeast REC gene mutations that includes both hyper-rec and hypo-rec mutants. Five phenotypic classes of rec variants have been identified based upon their effects on spontaneous mitotic gene conversion and intergenic recombination. Their characteristics demonstrate that mitotic gene conversion and intergenic recombination are under independent as well as coordinate genetic control. Four gene mutations affecting recombination rad50, rad52, rem1 and spo11 have been extensively examined in several laboratories and illustrate the information that can be obtained by characterization of double mutant strains, detailed genotypic analysis of recombinants, and studies of meiotic recombination in cells in which the reductional division of meiosis has been bypassed by the spo13 mutation.
酿酒酵母中的重组一直是广泛遗传学研究的主题，这些研究记录了基因内和基因间重组的一般特性，以及有丝分裂和减数分裂基因转换与相互交换之间的差异。自发的有丝分裂和减数分裂事件在重组相对于染色体复制的起始时间、假定异源双链DNA区域的对称与不对称、基因内标记转换的极性以及经历同时转换的DNA片段长度方面存在差异。观察到的差异以及酵母rec突变的特性为有丝分裂和减数分裂重组的多种模式或途径提供了证据。已经提出了几种重组分子模型来解释遗传重组的基本参数以及有丝分裂和减数分裂重组之间的差异。由于这些模型在组成重组的部分反应方面存在差异，它们预测了不同类别的低重组和高重组rec突变体的分离。我们已经分离出了广泛的酵母REC基因突变体，其中包括高rec和低rec突变体。根据rec变体对自发有丝分裂基因转换和基因间重组的影响，已经鉴定出了五类表型。它们的特征表明，有丝分裂基因转换和基因间重组受到独立以及协同的遗传控制。影响重组的四个基因突变rad50、rad52、rem1和spo11已经在几个实验室中得到了广泛研究，这些研究说明了通过双突变体菌株的表征、重组体的详细基因型分析以及对减数分裂的减数分裂被spo13突变绕过的细胞中的减数分裂重组研究可以获得的信息。
