Golin J E, Esposito M S
Mol Gen Genet. 1981;183(2):252-63. doi: 10.1007/BF00270626.
In a preliminary report (Esposito 1978), evidence was presented which showed that heteroallelic recombination resulting in prototrophic colonies occurs at the 2-strand stage. A model utilizing replicative resolution of Holliday structures was proposed to explain how gene conversion at the 2-strand stage can result in exchange of outside markers. The object of the experiments reported herein was to present detailed genetic evidence for 2-strand recombination. In addition, we examined the features of mitotic recombination with respect to symmetry, length and polarity of heteroduplexes in wild type strains (REM1/REM1) and in strains bearing the hyper-recombination mutation rem1-1. To do this, we constructed strains so that prototrophs arising from heteroallelic recombination and recombinant for outside markers were detected by visual inspection. By analyzing these colonies genetically, we have inferred several features of mitotic recombination which distinguish it from its meiotic counterpart. Firstly, mitotic heteroduplexes are often symmetric while meiotic heteroduplexes are almost exclusively asymmetric. Secondly, heteroduplexes tend to be longer in mitosis that in meiosis. Thirdly, unlike meiotic conversion, mitotic conversion does not show strong polarity. Recombination in strains homozygous for the rem1-1 mutation also takes place at the 2-strand stage. The rem1-1 mutation, however, appears to alter the features of mismatch correction.
在一份初步报告（埃斯波西托，1978年）中，有证据表明，导致原养型菌落的异等位基因重组发生在双链阶段。有人提出了一个利用霍利迪结构的复制性拆分的模型，来解释双链阶段的基因转换如何导致外部标记的交换。本文所报告的实验目的是提供双链重组的详细遗传证据。此外，我们研究了野生型菌株（REM1/REM1）和携带高重组突变rem1-1的菌株中，有丝分裂重组在异源双链体的对称性、长度和极性方面的特征。为此，我们构建了一些菌株，以便通过肉眼观察来检测由异等位基因重组产生的原养型以及外部标记的重组体。通过对这些菌落进行遗传分析，我们推断出了有丝分裂重组的几个特征，这些特征将它与其减数分裂对应物区分开来。首先，有丝分裂异源双链体通常是对称的，而减数分裂异源双链体几乎完全是不对称的。其次，有丝分裂中的异源双链体往往比减数分裂中的更长。第三，与减数分裂转换不同，有丝分裂转换没有显示出强烈的极性。rem1-1突变纯合菌株中的重组也发生在双链阶段。然而，rem1-1突变似乎改变了错配校正的特征。
