The distribution pattern of the meiotic machinery in known eukaryotes is most parsimoniously explained by the hypothesis that all eukaryotes are ancestrally sexual. However, this assumption is questioned by preliminary results, in culture conditions. These suggested that Acanthamoeba, an organism considered to be largely asexual, constitutively expresses meiosis genes nevertheless—at least in the lab. This apparent disconnect between the “meiosis toolkit” and sexual processes in Acanthamoeba led to the conclusion that the eukaryotic ancestor is asexual. In this review, the “meiosis toolkit” is rigorously defended, drawing on numerous research articles. Additionally, the claim of constitutive meiotic gene expression is probed in Acanthamoeba via the same transcriptomics data. The results show that the expression of the meiotic machinery is not constitutive in Acanthamoeba as claimed before. Furthermore, it is argued that this would have no implications for understanding the nature of the eukaryotic ancestor, regardless of the result.

中文翻译：

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所有真核生物的性祖先：“减数分裂工具包”的辩护：一项严格的调查支持减数分裂机制与性重组之间的必然联系。

已知真核生物中减数分裂机制的分布模式最简洁地解释为所有真核生物都是祖先有性的假设。然而，这种假设在培养条件下受到初步结果的质疑。这些表明棘阿米巴，一种被认为主要是无性的生物，尽管如此，仍然组成性地表达减数分裂基因——至少在实验室中是这样。棘阿米巴“减数分裂工具包”和性过程之间的这种明显脱节导致了真核祖先是无性的结论。在这篇评论中，“减数分裂工具包”得到了严格的辩护，借鉴了大量的研究文章。此外，在棘阿米巴中探讨了组成型减数分裂基因表达的主张通过相同的转录组学数据。结果表明减数分裂机制的表达在棘阿米巴中不是组成性的，如前所述。此外，有人认为，无论结果如何，这对理解真核祖先的性质没有任何意义。