Fung Jennifer C, Rockmill Beth, Odell Michael, Roeder G Shirleen
Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA.
Cell. 2004 Mar 19;116(6):795-802. doi: 10.1016/s0092-8674(04)00249-1.
Meiotic crossovers (COs) are nonrandomly distributed along chromosomes such that two COs seldom occur close together, a phenomenon known as CO interference. We have used genetic and cytological methods to investigate interference mechanisms in budding yeast. Assembly of the synaptonemal complex (SC) initiates at a few sites along each chromosome, triggered by a complex of proteins (including Zip2 and Zip3) called the synapsis initiation complex (SIC). We found that SICs, like COs, display interference, supporting the hypothesis that COs occur at synapsis initiation sites. Unexpectedly, we found that SICs show interference in mutants in which CO interference is abolished; one explanation is that these same mutations eliminate the subset of COs that normally occur at SICs. Since SICs are assembled in advance of SC and they are properly positioned even in the absence of SC formation, these data clearly demonstrate an aspect of interference that is independent of synapsis.
减数分裂交叉（COs）沿染色体呈非随机分布，以至于两个CO很少紧密相邻发生，这种现象称为CO干扰。我们利用遗传学和细胞学方法研究了芽殖酵母中的干扰机制。联会复合体（SC）的组装在每条染色体上的几个位点起始，由一种称为联会起始复合体（SIC）的蛋白质复合体（包括Zip2和Zip3）触发。我们发现，SIC与CO一样，也表现出干扰，这支持了CO发生在联会起始位点的假说。出乎意料的是，我们发现在CO干扰被消除的突变体中，SIC仍表现出干扰；一种解释是，这些相同的突变消除了通常在SIC处发生的那部分CO。由于SIC在SC之前组装，并且即使在没有SC形成的情况下它们也能正确定位，这些数据清楚地证明了干扰的一个与联会无关的方面。
