Selection against deleterious LINE-1-containing loci in the human lineage
Selection against deleterious LINE-1-containing loci in the human lineage
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DOI：
10.1093/oxfordjournals.molbev.a003893
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发表时间：
2001-06-01
影响因子：
10.7
通讯作者：
Furano, AV
中科院分区：
文献类型：
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作者：
Boissinot, S;Entezam, A;Furano, AV
我们比较了性染色体和常染色体区域相似的GC含量，发现人类Y染色体每兆碱基包含的全长（FL）祖先LINE-1（L1）元件是常染色体的9倍，X染色体包含的元件是常染色体的3倍。此外，两个性染色体都含有一个ca。超过两倍的元件，其> 500 bp但不足以长到能够自主复制。相反，常染色体相对于性染色体不缺乏短（< 500 bp）L1元件或SINE元件。由于无论是Y还是X染色体，当存在于男性，可以清除有害的遗传位点的重组，我们的结论是，大多数FL L1是有害的，因此受到净化选择。21号常染色体非重组区和重组区的比较支持这一结论。我们能够在人类DNA数据库中识别出一个曾经包含活性L1元件的基因座子集，并且我们通过使用聚合酶链反应发现，其中72%的基因座在8个不同种族的代表中不再包含L1元件。L1反转录转座和L1元件之间的异位（非等位）重组产生的遗传损伤可能为其负选择提供了基础。
We compared sex chromosomal and autosomal regions of similar GC contents and found that the human Y chromosome contains nine times as many full-length (FL) ancestral LINE-1 (L1) elements per megabase as do autosomes and that the X chromosome contains three times as many. In addition, both sex chromosomes contain a ca. twofold excess of elements that are > 500 bp but not long enough to be capable of autonomous replication. In contrast, the autosomes are not deficient in short (< 500 bp) L1 elements or SINE elements relative to the sex chromosomes. Since neither the Y nor the X chromosome, when present in males, can be cleared of deleterious genetic loci by recombination, we conclude that most FL L1s were deleterious and thus subject to purifying selection. Comparison between nonrecombining and recombining regions of autosome 21 supported this conclusion. We were able to identify a subset of loci in the human DNA database that once contained active L1 elements, and we found by using the polymerase chain reaction that 72% of them no longer contain L1 elements in a representative of each of eight different ethnic groups. Genetic damage produced by both L1 retrotransposition and ectopic (nonallelic) recombination between L1 elements could provide the basis for their negative selection.