Brauchle Michael, Kiontke Karin, MacMenamin Philip, Fitch David H A, Piano Fabio
Department of Biology, New York University, New York, NY 10003, USA.
Dev Biol. 2009 Nov 1;335(1):253-62. doi: 10.1016/j.ydbio.2009.07.033. Epub 2009 Jul 28.
The cell-biological events that guide early-embryonic development occur with great precision within species but can be quite diverse across species. How these cellular processes evolve and which molecular components underlie evolutionary changes is poorly understood. To begin to address these questions, we systematically investigated early embryogenesis, from the one- to the four-cell embryo, in 34 nematode species related to C. elegans. We found 40 cell-biological characters that captured the phenotypic differences between these species. By tracing the evolutionary changes on a molecular phylogeny, we found that these characters evolved multiple times and independently of one another. Strikingly, all these phenotypes are mimicked by single-gene RNAi experiments in C. elegans. We use these comparisons to hypothesize the molecular mechanisms underlying the evolutionary changes. For example, we predict that a cell polarity module was altered during the evolution of the Protorhabditis group and show that PAR-1, a kinase localized asymmetrically in C. elegans early embryos, is symmetrically localized in the one-cell stage of Protorhabditis group species. Our genome-wide approach identifies candidate molecules-and thereby modules-associated with evolutionary changes in cell-biological phenotypes.
指导早期胚胎发育的细胞生物学事件在物种内部精确发生，但在不同物种间可能差异很大。这些细胞过程如何进化以及进化变化背后的分子成分是什么，目前还知之甚少。为了开始解决这些问题，我们系统地研究了与秀丽隐杆线虫相关的34种线虫物种从单细胞胚胎到四细胞胚胎的早期胚胎发育过程。我们发现了40个细胞生物学特征，这些特征捕捉到了这些物种之间的表型差异。通过在分子系统发育树上追踪进化变化，我们发现这些特征多次独立进化。令人惊讶的是，所有这些表型都可以通过秀丽隐杆线虫的单基因RNA干扰实验模拟出来。我们利用这些比较来推测进化变化背后的分子机制。例如，我们预测在原杆线虫类群的进化过程中，一个细胞极性模块发生了改变，并表明PAR-1（一种在秀丽隐杆线虫早期胚胎中不对称定位的激酶）在原杆线虫类群物种的单细胞阶段对称定位。我们的全基因组方法识别出了与细胞生物学表型进化变化相关的候选分子——从而识别出了相关模块。
