Duplication, balancing selection and trans-species evolution explain the high levels of polymorphism of the DQA MHC class II gene in voles (Arvicolinae)
Duplication, balancing selection and trans-species evolution explain the high levels of polymorphism of the DQA MHC class II gene in voles (Arvicolinae)
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DOI：
10.1007/s00251-006-0085-6
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发表时间：
2006-04-01
期刊：
影响因子：
3.2
通讯作者：
Cosson, JF
中科院分区：
文献类型：
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作者：
Bryja, J;Galan, M;Cosson, JF
主要组织相容性复合体（MHC）基因在宿主-寄生虫相互作用中起重要作用，寄生虫是影响宿主种群动态的关键因素。我们描述的结构和多样性的MHCII类DQA基因的外显子2在三种田鼠（Arvicolinae）表现出定期多年的人口密度波动，并分析了导致观察到的MHC多态性的过程。通过使用克隆测序方法和毛细管电泳-单链构象多态性，我们描述了7个序列在水中，8个在常见的，和7个在银行田鼠来自一个地区的70公里（2）周围的Nozeroy州在汝拉山（弗朗什孔德，法国）。所有外显子2序列翻译得到独特的氨基酸序列，发现正选择作用于抗原结合位点非常强烈。我们记录了在田鼠DQA区域的重组的存在，但它的重要性产生等位基因多态性似乎是相对有限的。在啮齿类动物中，我们第一次记录了DQA基因在所有三个物种中的重复，两个拷贝都具有转录活性。等位基因序列的系统发育分析揭示了广泛的跨物种多态性的亚科内，虽然没有等位基因在我们的数据集物种之间共享。我们讨论了可能的作用，寄生虫在形成最近的多态性模式的DQA基因座在田鼠。
Major histocompatibility complex (MHC) genes play important role in host-parasite interactions and parasites are crucial factors influencing the population dynamics of hosts. We described the structure and diversity of exon 2 of the MHC class II DQA gene in three species of voles (Arvicolinae) exhibiting regular multi-annual fluctuations of population density and analysed the processes leading to the observed MHC polymorphism. By using cloning-sequencing methodology and capillary electrophoresis-single strand conformation polymorphism, we described seven sequences in the water, eight in the common, and seven in the bank voles coming from an area of 70 km(2) around the Nozeroy canton in the Jura Mountains (Franche Comte, France). All exon 2 sequences translate to give unique amino acid sequences and positive selection was found to act very intensively on antigen binding sites. We documented the presence of recombination at vole DQA region but its importance in generating allelic polymorphism seems to be relatively limited. For the first time within rodents, we documented the duplication of the DQA gene in all three species with both copies being transcriptionally active. Phylogenetic analysis of allelic sequences revealed extensive trans-species polymorphism within the subfamily although no alleles were shared between species in our data set. We discuss possible role of parasites in forming the recent polymorphism pattern of the DQA locus in voles.