《Science》第一个真核细胞如何形成 解密进化难题

　　

生物通报道，为纪念达尔文诞生200年，Science杂志推出了系列文章解析生命起源的问题，在本年的第八篇文章中，Carl Zimmer介绍了生命的起源历史进程。

 

重点介绍了真核细胞的起源问题。第一个真核细胞是如何产生的，在历史的长河中这些单个细胞如何变成多细胞生物……

 

最早的真核生物化石已有20亿年的历史，从20亿年前到如今，生命已经经历多次的变化，要想了解真核多细胞生物的进化史就必须找到每个不同时代的生物化石。遗憾的是，中间有不少过渡型化石没有被找到。

 

古生物学家对此十分的遗憾，于是，他们开辟了新的研究路径，不从化石的途径来研究，而从现今存活的生物来进行研究。古生物学家找到了一些活化石，也就是现今都存活的早期的真核生物和原核生物，从细胞生物学角度和基因组角度都能找出进化的痕迹和线索。

 

随着技术的进步，近20年来，进化的研究取得了翻天覆地的变化。比如说，基因组测序技术就已经取得了质的飞跃，从基因组上比对两种生物变得更为容易了。

 

目前比较重要的理论认为，细菌在进化过程中发挥了关键的作用。研究人员认为某些细菌携带的基因变成了真核细胞的线粒体。但是，有些科学家却不这么认为，他们认为细菌携带的基因是促成真核细胞进化的关键，包括促进原核细胞进化出有膜的细胞核。

（生物通 小茜）

生物通推荐原文摘要

On the Origin of Eukaryotes

Carl Zimmer

In the eighth essay in Science's series in honor of the Year of Darwin, Carl Zimmer describes one of the most important transitions in the history of life: the origin of cells with a nucleus, which gave rise to every multicellular form of life. The fossil record doesn't tell us much: The earliest fossils that have been proposed to be eukaryotes are only about 2 billion years old, and paleontologists have not yet discovered any transitional forms. Fortunately, living eukaryotes and prokaryotes, cells that lack a nucleus, still retain some clues to the transition, both in their cell biology and in their genomes. By studying both, researchers have made tremendous advances in the past 20 years in understanding how eukaryotes first emerged. A key step in their evolution, for example, was the acquisition of bacterial passengers, which eventually became the mitochondria of eukaryote cells. But some scientists now argue that the genes of these bacteria also helped give rise to other important features of the eukaryote cell, including the nucleus.