Houlden B A, Greville W D, Sherwin W B
School of Biological Science, University of NSW, Australia.
Mol Biol Evol. 1996 Oct;13(8):1119-27. doi: 10.1093/oxfordjournals.molbev.a025674.
We demonstrate that koala (Phascolarctos cinereus) MHC class I constitutes a variable multigene family. A total of nine partial exon 2 and 3 major histocompatibility complex (MHC) class I sequences are presented, including six sequences from at least three loci from one koala. Variation was detected by examination of sequences from a number of individuals and family groups. The koala is the second marsupial species characterized to date, and comparisons reveal approximately 80% similarity with sequences from the red necked wallaby (Macropus rufogriseus). The latter sequences represent at least two, and probably three, different loci. Phylogenetic analysis demonstrates that all koala sequences are more related to one another than they are to any of the wallaby loci. This indicates that the koala sequences are probably not orthologous to the wallaby genes, and thus represent a new class I gene family. In addition, marsupial gene families cluster away from human gene families, supporting a different origin of MHC genes for marsupials and eutherians.
我们证明，考拉（树袋熊，Phascolarctos cinereus）的主要组织相容性复合体I类（MHC I）构成了一个可变的多基因家族。本文呈现了总共9个主要组织相容性复合体（MHC）I类外显子2和3的部分序列，其中包括来自一只考拉至少三个基因座的6个序列。通过检查多个个体和家族群体的序列检测到了变异。考拉是迄今为止第二个被表征的有袋类物种，比较结果显示其与红颈小袋鼠（Macropus rufogriseus）的序列相似度约为80%。后者的序列代表至少两个，可能三个不同的基因座。系统发育分析表明所有考拉序列彼此之间的亲缘关系比它们与任何小袋鼠基因座的亲缘关系都更近。这表明考拉序列可能与小袋鼠基因并非直系同源，因此代表了一个新的I类基因家族。此外，有袋类基因家族与人类基因家族聚类分离，支持了有袋类和真兽类MHC基因起源不同的观点。
