Martin William F, Weiss Madeline C, Neukirchen Sinje, Nelson-Sathi Shijulal, Sousa Filipa L
Institute for Molecular Evolution, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf, Germany. ; Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2780-157 Oeiras, Portugal.
Institute for Molecular Evolution, Heinrich-Heine Universität Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf, Germany.
Microb Cell. 2016 Nov 25;3(12):582-587. doi: 10.15698/mic2016.12.545.
Genomes record their own history. But if we want to look all the way back to life's beginnings some 4 billion years ago, the record of microbial evolution that is preserved in prokaryotic genomes is not easy to read. Microbiology has a lot in common with geology in that regard. Geologists know that plate tectonics and erosion have erased much of the geological record, with ancient rocks being truly rare. The same is true of microbes. Lateral gene transfer (LGT) and sequence divergence have erased much of the evolutionary record that was once written in genomes, and it is not obvious which genes among sequenced genomes are genuinely ancient. Which genes trace to the last universal ancestor, LUCA? The classical approach has been to look for genes that are universally distributed. Another approach is to make all trees for all genes, and sift out the trees where signals have been overwritten by LGT. What is left ought to be ancient. If we do that, what do we find?
基因组记录着自身的历史。但如果我们想一直追溯到约40亿年前生命的起源，保存在原核生物基因组中的微生物进化记录并不容易解读。在这方面，微生物学与地质学有很多共同之处。地质学家知道板块构造和侵蚀已经抹去了大部分地质记录，古老的岩石非常罕见。微生物也是如此。横向基因转移（LGT）和序列分歧已经抹去了曾经写在基因组中的许多进化记录，而且在已测序的基因组中，哪些基因是真正古老的并不明显。哪些基因可以追溯到最后的共同祖先，即LUCA？经典的方法是寻找普遍分布的基因。另一种方法是为所有基因构建所有的树，并筛选出信号被LGT覆盖的树。剩下的应该就是古老的。如果我们这样做，会发现什么呢？
