Unprecedented intraspecific diversity of the MHC class I region of a teleost medaka, Oryzias latipes
Unprecedented intraspecific diversity of the MHC class I region of a teleost medaka, Oryzias latipes
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DOI：
10.1007/s00251-005-0009-x
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发表时间：
2005-07
期刊：
影响因子：
3.2
通讯作者：
Kentaro Tsukamoto;Shinpei Hayashi;M. Matsuo;M. Nonaka;M. Kondo;A. Shima;S. Asakawa;N. Shimizu;M. Nonaka
中科院分区：
文献类型：
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作者：
Kentaro Tsukamoto;Shinpei Hayashi;M. Matsuo;M. Nonaka;M. Kondo;A. Shima;S. Asakawa;N. Shimizu;M. Nonaka
主要组织相容性复合体（MHC）存在于迄今为止所分析的所有颌骨脊椎动物的单个染色体位点，从鲨鱼到哺乳动物，除了硬骨鱼，其同源的哺乳动物MHC编码基因分散在几个染色体位点上。即使在硬骨鱼中，一些IA类基因和那些直接参与I类抗原呈递的基因保留了它们的连锁，定义了硬骨鱼MHC I类区域。我们从四个重叠的细菌人工染色体（BAC）克隆中测定了medaka，Oryzias latipes（日本北部种群）的HNI近交系MHC I类区域的完整核苷酸序列，并将其与medaka近交系Hd-rR菌株（425,935 bp，日本南部种群）相应区域的序列进行了比较，作为对变热MHC区域的种内多态性的首次广泛研究。在比较的序列中间有一个约100 kb的片段，包含两个Ia类基因和两个免疫蛋白酶体亚基基因psmb8和psmb10，在这两个自交系株之间存在如此大的差异，以至于无法进行可靠的序列比对。其余比较区域（约320 kb）显示出相当的对应性，并且在无间隙片段比对中观察到大约96%的核苷酸同源性。这些结果表明，medaka MHC I类区域包含一个约100 kb的多态性核心，这很可能是通过点突变的积累和广泛的遗传重排（如插入、缺失和重复）进行适应性进化的。
The major histocompatibility complex (MHC) is present at a single chromosomal locus of all jawed vertebrate analyzed so far, from sharks to mammals, except for teleosts whose orthologs of the mammalian MHC-encoded genes are dispersed at several chromosomal loci. Even in teleosts, several class IA genes and those genes directly involved in class I antigen presentation preserve their linkage, defining the teleost MHC class I region. We determined the complete nucleotide sequence of the MHC class I region of the inbred HNI strain of medaka,Oryzias latipes(northern Japan population-derived), from four overlapping bacterial artificial chromosome (BAC) clones spanning 540,982 bp, and compared it with the published sequence of the corresponding region of the inbred Hd-rR strain of medaka (425,935 bp, southern Japan population-derived) as the first extensive study of intraspecies polymorphisms of the ectotherm MHC regions. A segment of about 100 kb in the middle of the compared sequences encompassing two class Ia genes and two immunoproteasome subunit genes,PSMB8andPSMB10, was so divergent between these two inbred strains that a reliable sequence alignment could not be made. The rest of the compared region (about 320 kb) showed a fair correspondence, and an approximately 96% nucleotide identity was observed upon gap-free segmental alignment. These results indicate that the medaka MHC class I region contains an ∼100-kb polymorphic core, which is most probably evolving adaptively by accumulation of point mutations and extensive genetic rearrangements such as insertions, deletions and duplications.