Bogdanov Yu F
Genetika. 2016 May;52(5):541-60.
Inverted meiosis is observed in plants (Cyperaceae and Juncaceae) and insects (Coccoidea, Aphididae) with holocentric chromosomes, the centromeres of which occupy from 70 to 90% of the metaphase chromosome length. In the first meiotic division (meiosis I), chiasmata are formed and rodlike bivalents orient equationally, and in anaphase I, sister chromatids segregate to the poles; the diploid chromosome number is maintained. Non-sister chromatids of homologous chromosomes remain in contact during interkinesis and prophase II and segregate in anaphase II, forming haploid chromosome sets. The segregation of sister chromatids in meiosis I was demonstrated by example of three plant species that were heterozygous for chromosomal rearrangements. In these species, sister chromatids, marked with rearrangement, segregated in anaphase I. Using fluorescent antibodies, it was demonstrated that meiotic recombination enzymes Spo11 and Rad5l, typical of canonical meiosis, functioned at the meiotic prophase I of pollen mother cells of Luzula elegance and Rhynchospora pubera. Moreover, antibodies to synaptonemal complexes proteins ASY1 and ZYP1 were visualized as filamentous structures, pointing to probable formation of synaptonemal complexes. In L. elegance, chiasmata are formed by means of chromatin threads containing satellite DNA. According to the hypothesis of the author of this review, equational division of sister chromatids at meiosis I in the organisms with inverted meiosis can be explained by the absence of specific meiotic proteins (shugoshins). These proteins are able to protect cohesins of holocentric centromeres from hydrolysis by separases at meiosis I, as occurs in the organisms with monocentric chromosomes and canonical meiosis. The basic type of inverted meiosis was described in Coccoidea and Aphididae males. In their females, the variants of parthenogenesis were also observed. Until now, the methods of molecular cytogenetics were not applied for the analysis of inverted meiosis in Coccoidea and Aphididae. Evolutionary, inverted meiosis is thought to have appeared secondarily as an adaptation of the molecular mechanisms of canonical meiosis to chromosome holocentrism.
在具有全着丝粒染色体的植物（莎草科和灯心草科）和昆虫（蚧总科、蚜科）中观察到了反向减数分裂，其着丝粒占据中期染色体长度的70%至90%。在第一次减数分裂（减数分裂I）中，交叉形成，棒状二价体以均等方式定向，在后期I，姐妹染色单体分离至两极；二倍体染色体数目得以维持。同源染色体的非姐妹染色单体在减数分裂间期和前期II保持接触，并在后期II分离，形成单倍体染色体组。通过三个对染色体重排杂合的植物物种的实例证明了减数分裂I中姐妹染色单体的分离。在这些物种中，带有重排标记的姐妹染色单体在后期I分离。使用荧光抗体证明，典型的常规减数分裂的减数分裂重组酶Spo11和Rad5l在优雅地杨梅和毛喙刺子莞花粉母细胞的减数分裂前期I发挥作用。此外，联会复合体蛋白ASY1和ZYP1的抗体被可视化为丝状结构，表明可能形成了联会复合体。在优雅地杨梅中，交叉是通过含有卫星DNA的染色质丝形成的。根据本综述作者的假设，在具有反向减数分裂的生物体中，减数分裂I时姐妹染色单体的均等分裂可以通过缺乏特定的减数分裂蛋白（守护蛋白）来解释。这些蛋白能够保护全着丝粒着丝粒的黏连蛋白在减数分裂I时不被分离酶水解，就像在具有单着丝粒染色体和常规减数分裂的生物体中那样。反向减数分裂的基本类型在蚧总科和蚜科雄性中有所描述。在它们的雌性中也观察到了孤雌生殖的变体。到目前为止，分子细胞遗传学方法尚未应用于蚧总科和蚜科反向减数分裂的分析。从进化角度来看，反向减数分裂被认为是常规减数分裂的分子机制对染色体全着丝粒状态的一种次生适应而出现的。
