Zhao Zhongying, Boyle Thomas J, Bao Zhirong, Murray John I, Mericle Barbara, Waterston Robert H
Department of Genome Sciences, Box 355065, University of Washington, 1705 NE Pacific St, Seattle, WA 98195-5065, USA.
Dev Biol. 2008 Feb 1;314(1):93-9. doi: 10.1016/j.ydbio.2007.11.015. Epub 2007 Nov 22.
Comparative genomic analysis of important signaling pathways in Caenorhabditis briggsae and Caenorhabditis elegans reveals both conserved features and also differences. To build a framework to address the significance of these features we determined the C. briggsae embryonic cell lineage, using the tools StarryNite and AceTree. We traced both cell divisions and cell positions for all cells through all but the last round of cell division and for selected cells through the final round. We found the lineage to be remarkably similar to that of C. elegans. Not only did the founder cells give rise to similar numbers of progeny, the relative cell division timing and positions were largely maintained. These lineage similarities appear to give rise to similar cell fates as judged both by the positions of lineally equivalent cells and by the patterns of cell deaths in both species. However, some reproducible differences were seen, e.g., the P4 cell cycle length is more than 40% longer in C. briggsae than that in C. elegans (p<0.01). The extensive conservation of embryonic development between such divergent species suggests that substantial evolutionary distance between these two species has not altered these early developmental cellular events, although the developmental defects of transpecies hybrids suggest that the details of the underlying molecular pathways have diverged sufficiently so as to not be interchangeable.
对秀丽隐杆线虫和briggsae线虫重要信号通路的比较基因组分析揭示了保守特征和差异。为构建一个框架来探讨这些特征的重要性，我们使用StarryNite和AceTree工具确定了briggsae线虫的胚胎细胞谱系。我们追踪了除最后一轮细胞分裂外所有细胞的细胞分裂和细胞位置，并在最后一轮追踪了选定细胞的情况。我们发现该谱系与秀丽隐杆线虫的谱系非常相似。不仅奠基细胞产生的后代数量相似，相对细胞分裂时间和位置也基本保持一致。从直系同源细胞的位置以及两个物种中的细胞死亡模式判断，这些谱系相似性似乎导致了相似的细胞命运。然而，也观察到了一些可重复的差异，例如，briggsae线虫中P4细胞周期长度比秀丽隐杆线虫长40%以上（p<0.01）。如此不同的物种之间胚胎发育的广泛保守性表明，尽管种间杂种的发育缺陷表明潜在分子途径的细节已经足够分化以至于不可互换，但这两个物种之间巨大的进化距离并未改变这些早期发育细胞事件。
