Canonical meiosis is characterized by two sequential rounds of nuclear divisions following one round of DNA replication—reductional segregation of homologous chromosomes during the first division and equational segregation of sister chromatids during the second division. Meiosis in an inverted order of two nuclear divisions—inverted meiosis has been observed in several species with holocentromeres as an adaptive strategy to overcome the obstacle in executing a canonical meiosis due to the holocentric chromosome structure. Recent findings of co-existence of inverted and canonical meiosis in two monocentric organisms, human and fission yeast, suggested that inverted meiosis could be common and also lead to the puzzle regarding the mechanistic feasibility for executing two meiosis programs simultaneously. Here, we discuss apparent conflicts for concurrent canonical meiosis and inverted meiosis. Furthermore, we attempt to provide a working model that may be compatible for both forms of meiosis.

中文翻译：

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反向减数分裂：繁殖的染色体分离的另一种方法。

典型的减数分裂的特征是，在进行一轮DNA复制后，连续进行了两轮核分裂-第一次分裂时同源染色体的还原性分离和第二次分裂时姐妹染色单体的等式分离。减数分裂以两个核分裂的倒序排列-在具有整体着丝粒的几种物种中已经观察到倒数减数分裂是一种适应性策略，可以克服由于整体中心染色体结构而导致执行标准减数分裂的障碍。最近在人类和裂变酵母这两个单中心生物中同时存在倒数减数分裂和规范减数分裂的研究结果表明，倒数减数分裂可能很常见，也引起了同时执行两个减数分裂程序的机械可行性的困惑。这里，我们讨论了同时发生的典型减数分裂和倒数减数分裂的明显冲突。此外，我们尝试提供一种可能与两种减数分裂形式都兼容的工作模型。