加拿大麦吉尔大学Ehab Abouheif课题组取得最新进展。他们揭示了个体重大进化过渡的起源和完善。2020年9月2日，《自然》杂志发表了这一成果。
研究人员显示，与其他昆虫相比，细菌黑斑病与超多样性蚂蚁群落之间的专性内共生起源于胚胎，并且也通过根本性的改变而得以完善。在节肢动物中，通常将Hox基因Abdominal A（abdA）和Ultrabithorax（Ubx）形成，它们的功能是区分腹部和胸腔段，因此它们也被重新排布以调节发育早期的种系基因。因此，这些Hox基因的mRNA和蛋白质在母体中表达，并在亚细胞水平上与种质中的种系基因和新鲜产的卵中三个新位点共定位。然后，Blochmannia选择性地调节这些mRNA和蛋白质，以使这四个位置的每个在功能上截然不同，从而在胚胎中形成坐标系统，其中每个位置执行不同的功能以将Blochmannia整合到Camponotini中。
最后，研究人员证明了将mRNA和蛋白质定位到胚胎中新位置的能力在专性内共生之前就已经进化，随后被Blochmannia和Camponotini共同采用。这种既有的分子功能与既有的生态共生相融合，从而促进了Blochmannia属植物到Camponotini中的水平转移和发育整合。因此，先前存在的分子功能和生态相互作用的融合，以及高度保守的基因网络的重新排布，可能是促进个体主要转变的起源和细化的普遍特征。
据悉，专性内共生中密切相关的物种整合形成一个复制个体，代表了个体的主要进化过渡。尽管人们认为这种转变会增加生物的复杂性，但导致融合的进化和发育步骤仍然知之甚少。
附：英文原文
Title: Origin and elaboration of a major evolutionary transition in individuality
Author: Ab. Matteen Rafiqi, Arjuna Rajakumar, Ehab Abouheif
Issue&Volume: 2020-09-02
Abstract: Obligate endosymbiosis, in which distantly related species integrate to form a single replicating individual, represents a major evolutionary transition in individuality1,2,3. Although such transitions are thought to increase biological complexity1,2,4,5,6, the evolutionary and developmental steps that lead to integration remain poorly understood. Here we show that obligate endosymbiosis between the bacteria Blochmannia and the hyperdiverse ant tribe Camponotini7,8,9,10,11 originated and also elaborated through radical alterations in embryonic development, as compared to other insects. The Hox genes Abdominal A (abdA) and Ultrabithorax (Ubx)—which, in arthropods, normally function to differentiate abdominal and thoracic segments after they form—were rewired to also regulate germline genes early in development. Consequently, the mRNAs and proteins of these Hox genes are expressed maternally and colocalize at a subcellular level with those of germline genes in the germplasm and three novel locations in the freshly laid egg. Blochmannia bacteria then selectively regulate these mRNAs and proteins to make each of these four locations functionally distinct, creating a system of coordinates in the embryo in which each location performs a different function to integrate Blochmannia into the Camponotini. Finally, we show that the capacity to localize mRNAs and proteins to new locations in the embryo evolved before obligate endosymbiosis and was subsequently co-opted by Blochmannia and Camponotini. This pre-existing molecular capacity converged with a pre-existing ecological mutualism12,13 to facilitate both the horizontal transfer10 and developmental integration of Blochmannia into Camponotini. Therefore, the convergence of pre-existing molecular capacities and ecological interactions—as well as the rewiring of highly conserved gene networks—may be a general feature that facilitates the origin and elaboration of major transitions in individuality.
DOI: 10.1038/s41586-020-2653-6
Source: https://www.nature.com/articles/s41586-020-2653-6
Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
投稿链接：http://www.nature.com/authors/submit_manuscript.html
本期文章：《自然》：Online/在线发表
