Kiryu Ikunari, Dijkstra Johannes Martinus, Sarder Rafiqul Islam, Fujiwara Atsushi, Yoshiura Yasutoshi, Ototake Mitsuru
Inland Station/National Research Institute of Aquaculture, Fisheries Research Agency, Tamaki, Mie 519-0423, Japan.
Fish Shellfish Immunol. 2005 Mar;18(3):243-54. doi: 10.1016/j.fsi.2004.07.007.
Major histocompatibility complex (MHC) class Ia genes in salmonid fishes are encoded by a single locus with probably the highest allelic diversity ever described. Various combinations of very different domain lineages contribute to the diversity of alleles. An extensive PCR survey distinguishing most domain lineages and their combinations was established. This survey has practical value for researchers investigating salmonid MHC class Ia variation. In the present study it was used to find new domain lineages. Applied for 24 hatchery strains in Japan, the survey identified two new rainbow trout alpha1 lineages and one new rainbow trout alpha2 lineage. The alpha2 lineage and one of the alpha1 lineages had been described in Atlantic salmon, but the other alpha1 lineage is novel. The newly identified trout alpha1 lineages are evolutionary very old. The present study should be the most extensive description of very deep MHC class Ia lineages to date: six trout alpha1 lineages cluster with non-salmonid sequences whereas previous studies mentioned this for only two salmonid alpha1 lineages. Although exon-shuffling events significantly contributed to salmonid MHC class Ia variation, analysis of 800 trout siblings did not detect such events within a single generation.
鲑科鱼类的主要组织相容性复合体（MHC）I类a基因由一个位点编码，其等位基因多样性可能是迄今所描述的最高的。非常不同的结构域谱系的各种组合促成了等位基因的多样性。建立了一项广泛的PCR调查，可区分大多数结构域谱系及其组合。这项调查对研究鲑科鱼类MHC I类a变异的研究人员具有实际价值。在本研究中，它被用于发现新的结构域谱系。应用于日本的24个孵化场菌株，该调查确定了两个新的虹鳟α1谱系和一个新的虹鳟α2谱系。α2谱系和其中一个α1谱系已在大西洋鲑中被描述，但另一个α1谱系是新的。新鉴定的鳟鱼α1谱系在进化上非常古老。本研究应该是迄今为止对非常深的MHC I类a谱系最广泛的描述：六个鳟鱼α1谱系与非鲑科序列聚类，而以前的研究仅提及两个鲑科α1谱系有这种情况。尽管外显子重排事件对鲑科鱼类MHC I类a变异有显著贡献，但对800条鳟鱼同胞的分析在单一代内未检测到此类事件。
