Extensive genomic duplication during early chordate evolution
Extensive genomic duplication during early chordate evolution
复制标题
DOI：
10.1038/ng884
复制
发表时间：
2002-06-01
期刊：
影响因子：
30.8
通讯作者：
Wolfe, KH
中科院分区：
文献类型：
--
作者：
McLysaght, A;Hokamp, K;Wolfe, KH
关于古代基因组复制对脊椎动物基因组有贡献的假说（1），人们的观点从强烈的怀疑（2-4）到强烈的信任（5-7）。以前的研究集中在少量的基因家族或染色体区域，这些基因家族或染色体区域可能不代表整个基因组（4，5），或者使用主观方法来识别旁系同源基因和区域（5，8）。在这里，我们报告了一个系统的和客观的分析人类基因组序列草案，以确定旁系同源染色体区域（旁系同源）脊索动物进化过程中形成的，并估计重复基因的年龄。我们发现，人类基因组中包含的旁系同源物比偶然预期的要多得多。对所有在果蝇和线虫中具有直系同源物的人类蛋白质家族的分子钟分析表明，基因复制活动的爆发发生在3.5亿至6.5亿年前，并且此时形成的许多重复基因位于旁系同源物中。我们的研究结果支持了脊椎动物中许多基因家族是在早期脊索动物中通过大规模DNA复制形成或扩展的论点。考虑到序列数据的不完整性和事件的古老性，结果与至少一轮多倍体一致。
Opinions on the hypothesis(1) that ancient genome duplications contributed to the vertebrate genome range from strong skepticism(2-4) to strong credence(5-7). Previous studies concentrated on small numbers of gene families or chromosomal regions that might not have been representative of the whole genome(4,5), or used subjective methods to identify paralogous genes and regions(5,8). Here we report a systematic and objective analysis of the draft human genome sequence to identify paralogous chromosomal regions (paralogons) formed during chordate evolution and to estimate the ages of duplicate genes. We found that the human genome contains many more paralogons than would be expected by chance. Molecular clock analysis of all protein families in humans that have orthologs in the fly and nematode indicated that a burst of gene duplication activity took place in the period 350-650 Myr ago and that many of the duplicate genes formed at this time are located within paralogons. Our results support the contention that many of the gene families in vertebrates were formed or expanded by large- scale DNA duplications in an early chordate. Considering the incompleteness of the sequence data and the antiquity of the event, the results are compatible with at least one round of polyploidy.