Departamento de ZoologiaRua do Matão, Instituto de Biociências, Universidade de São Paulo, travessa 14, 101CEP., 05508-090, Sâo Paulo, Brazil.
Bioessays. 2019 Jun;41(6):e1800246. doi: 10.1002/bies.201800246. Epub 2019 May 14.
Here a wide distribution of meiotic machinery is shown, indicating the occurrence of sexual processes in all major eukaryotic groups, without exceptions, including the putative "asexuals." Meiotic machinery has evolved from archaeal DNA repair machinery by means of ancestral gene duplications. Sex is very conserved and widespread in eukaryotes, even though its evolutionary importance is still a matter of debate. The main processes in sex are plasmogamy, followed by karyogamy and meiosis. Meiosis is fundamentally a chromosomal process, which implies recombination and ploidy reduction. Several eukaryotic lineages are proposed to be asexual because their sexual processes are never observed, but presumed asexuality correlates with lack of study. The authors stress the complete lack of meiotic proteins in nucleomorphs and their almost complete loss in the fungus Malassezia. Inversely, complete sets of meiotic proteins are present in fungal groups Glomeromycotina, Trichophyton, and Cryptococcus. Endosymbiont Perkinsela and endoparasitic Microsporidia also present meiotic proteins.
这里展示了广泛分布的减数分裂机制，表明有性过程发生在所有主要的真核生物群中，无一例外，包括所谓的“无性生物”。减数分裂机制是通过祖先基因复制从古菌 DNA 修复机制进化而来的。性在真核生物中非常保守和普遍，尽管其进化重要性仍然存在争议。性的主要过程是质配，随后是核配和减数分裂。减数分裂从根本上说是一个染色体过程，它意味着重组和倍性降低。一些真核生物谱系被认为是无性的，因为它们的有性过程从未被观察到，但假定的无性与缺乏研究有关。作者强调指出，在核质体中完全缺乏减数分裂蛋白，在真菌 Malassezia 中几乎完全丧失。相反，在真菌类群 Glomeromycotina、Trichophyton 和 Cryptococcus 中存在全套的减数分裂蛋白。内共生菌 Perkinsela 和内寄生的微孢子虫也存在减数分裂蛋白。
