Department of Biology, Monmouth College, 700 East Broadway, Monmouth, IL 61430, USA.
Cell Biosci. 2012 Aug 22;2(1):29. doi: 10.1186/2045-3701-2-29.
For over a century, the origin of eukaryotes has been a topic of intense debate among scientists. Although it has become widely accepted that organelles such as the mitochondria and chloroplasts arose via endosymbiosis, the origin of the eukaryotic nucleus remains enigmatic. Numerous models for the origin of the nucleus have been proposed over the years, many of which use endosymbiosis to explain its existence. Proposals of microbes whose ancestors may have served as either a host or a guest in various endosymbiotic scenarios abound, none of which have been able to sufficiently incorporate the cell biological as well as phylogenetic data which links these organisms to the nucleus. While it is generally agreed that eukaryotic nuclei share more features in common with archaea rather than with bacteria, different studies have identified either one or the other of the two major groups of archaea as potential ancestors, leading to somewhat of a stalemate. This paper seeks to resolve this impasse by presenting evidence that not just one, but a pair of archaea might have served as host to the bacterial ancestor of the mitochondria. This pair may have consisted of ancestors of both Ignicoccus hospitalis as well as its ectosymbiont/ectoparasite 'Nanoarchaeum equitans'.
一个多世纪以来，真核生物的起源一直是科学家们激烈争论的话题。尽管人们普遍认为线粒体和叶绿体等细胞器是通过内共生作用产生的，但真核细胞核的起源仍然是个谜。多年来，人们提出了许多关于细胞核起源的模型，其中许多模型都利用内共生作用来解释其存在。提出了许多微生物的祖先可能在各种内共生场景中既作为宿主又作为访客，这些微生物的祖先可能在各种内共生场景中既作为宿主又作为访客，但是没有一个能够充分结合将这些生物与细胞核联系起来的细胞生物学和系统发育数据。虽然人们普遍认为真核细胞核与古菌的共同点多于与细菌的共同点，但不同的研究已经确定了古菌的两个主要群体中的一个或另一个可能是线粒体的细菌祖先的潜在祖先，这导致了一些僵局。本文试图通过提出证据来解决这一僵局，这些证据表明，不只是一种，而是一对古菌可能曾经是线粒体的细菌祖先的宿主。这一对古菌可能由 Ignicoccus hospitalis 的祖先以及它的外共生体/外寄生虫“Nanoarchaeum equitans”的祖先组成。
