Hypothesis that ancestral eukaryotes sexually proliferated without kinetochores or mitosis.

IF 3.3 3区 生物学 Q3 CELL BIOLOGY
Journal of cell science Pub Date : 2025-06-01 Epub Date: 2025-06-10 DOI:10.1242/jcs.263843
Bungo Akiyoshi
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引用次数: 0

Abstract

Eukaryotes possess two different mechanisms to transmit genetic material - mitosis and meiosis. Because mitosis is universal in all present-day eukaryotes, it has been widely assumed, despite the absence of definitive evidence, that meiosis evolved from mitosis during eukaryogenesis. In both processes, chromosome movement depends on interactions between spindle microtubules and a macromolecular protein complex called the kinetochore that assembles onto centromere DNA. Spindle microtubules consist of α- and β-tubulin subunits, which are conserved in all studied eukaryotes. Similarly, canonical kinetochore components are found in almost all eukaryotes. However, an evolutionarily divergent group of organisms called kinetoplastids has a unique set of kinetochore proteins. It remains unclear why and when different types of kinetochores evolved. In this Hypothesis article, I propose that the last eukaryotic common ancestor (LECA) did not have a kinetochore and that these two kinetochore systems evolved independently - one in the ancestor of kinetoplastids and another in the ancestor of all other eukaryotes. Based on the notion that archaea and the LECA possessed cell fusion and genetic exchange machineries, I further propose that key aspects of meiosis evolved prior to mitosis, challenging the dogma that meiosis evolved from mitosis.

假设祖先真核生物有性繁殖,没有着丝点或有丝分裂。
真核生物具有两种不同的传递遗传物质的机制——有丝分裂和减数分裂。由于有丝分裂在当今所有真核生物中都是普遍存在的,尽管缺乏明确的证据,但人们普遍认为减数分裂是真核发生过程中由有丝分裂进化而来的。在这两个过程中,染色体的运动都依赖于纺锤体微管和一种称为着丝点的大分子蛋白质复合物之间的相互作用,着丝点组装在着丝粒DNA上。纺锤体微管由α-和β-微管蛋白亚基组成,它们在所有研究的真核生物中都是保守的。类似地,在几乎所有真核生物中都能找到典型的着丝点成分。然而,一种进化上不同的生物体,称为着丝质体,有一套独特的着丝粒蛋白。目前尚不清楚不同类型的着丝点为何以及何时进化。在这篇假设文章中,我提出最后的真核生物共同祖先(LECA)没有着丝点,这两个着丝点系统是独立进化的——一个在着丝质体的祖先中,另一个在所有其他真核生物的祖先中。基于古细菌和LECA具有细胞融合和遗传交换机制的概念,我进一步提出减数分裂的关键方面在有丝分裂之前进化,挑战了减数分裂从有丝分裂进化而来的学说。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of cell science
Journal of cell science 生物-细胞生物学
CiteScore
7.30
自引率
2.50%
发文量
393
审稿时长
1.4 months
期刊介绍: Journal of Cell Science publishes cutting-edge science, encompassing all aspects of cell biology.
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