Watanabe Yoshinori
Institute of Molecular and Cellular Biosciences, and SORST, Japan Science and Technology Agency, University of Tokyo, Yayoi 1-1-1, Tokyo 113-0032, Japan.
J Cell Sci. 2004 Aug 15;117(Pt 18):4017-23. doi: 10.1242/jcs.01352.
Meiosis produces haploid gametes from diploid cells in two stages that in many ways resemble mitosis. However, the regulatory mechanisms governing kinetochore orientation and cohesion at the first meiotic division are different from those at mitosis: sister kinetochores are pulled forwards from the same spindle pole at metaphase, and centromeric cohesion is protected throughout anaphase. Consequently, homologous chromosomes, rather than sister chromatids, segregate to the opposite sides of a cell. The residual cohesion around centromeres plays an essential role at the second meiotic division, when spindle microtubules from opposite poles attach to sister chromatids. Recent studies have identified novel meiosis-specific kinetochore proteins, such as monopolin and shugoshin, and indicate that specific modifications in sister chromatid cohesion lie at the heart of the regulation of meiotic chromosome segregation.
减数分裂通过两个阶段从二倍体细胞产生单倍体配子，这两个阶段在许多方面类似于有丝分裂。然而，在第一次减数分裂中，控制动粒方向和黏连的调控机制与有丝分裂不同：在中期，姐妹动粒从同一纺锤体极向前拉动，并且着丝粒黏连在整个后期都受到保护。因此，同源染色体而非姐妹染色单体分离到细胞的相对两侧。着丝粒周围的残余黏连在第二次减数分裂中起着至关重要的作用，此时来自相对两极的纺锤体微管附着在姐妹染色单体上。最近的研究已经鉴定出了新的减数分裂特异性动粒蛋白，如单极纺锤体蛋白和守护蛋白，并表明姐妹染色单体黏连的特定修饰是减数分裂染色体分离调控的核心。
