Sequence Analyses of MHC Class II DQB Gene in Bottlenose Dolphins (Tursiops spp.) and the Other Delphinid Species from the Western Pacific

西太平洋瓶鼻海豚屬（Tursiops spp.）與其他海豚科動物之第二型主要組織相容性複合體DQB基因序列分析

楊瑋誠(Wei-Cheng Yang) ； 胡哲明(Jer-Ming Hu) ； 周蓮香(Lien-Siang Chou)

《臺灣獸醫學雜誌》 39卷2期 (2013/06) Pp. 100-109

摘要

主要組織相容性複合體（MHC）於脊椎動物免疫反應的啟動扮演重要的角色。我們採集台灣海域擱淺之20隻印太洋瓶鼻海豚（Tursiops adnucus）與3隻中華白海豚（Sousa chinensis）分析其MHC DQB基因座中第二外顯子之序列變異，以更了解繁衍興盛的海洋哺乳類之免疫多樣性。增幅之序列長為172個鹼基對，且每一個個體僅有一至兩條序列。高比例的非同義核酸取代與中等程度的變異暗示此基因座受到正向選汰壓的影響。此兩種棲息於沿岸海域的海豚與其他3種西太平洋海豚科動物之DQB第二外顯子序列之系統發生關係與其分類關係並不吻合，顯示這裡出現因病原驅動之指向性選汰導致的棲地特異性等位基因。

關鍵字

主要組織相容性複合體 ； DQB ； 瓶鼻海豚 ； 海豚科 ； 西太平洋

並列摘要

The major histocompatibility complex (MHC) plays a key role in the initiation of immune responses in vertebrates. The sequence variation of the exon 2 region of MHC DQB locus is analyzed using 20 Indo-Pacific bottlenose dolphins (Tursiops adnucus) and 3 Chinese white dolphin (Sousa chinensis) collected from strandings in Taiwanese waters for better understanding the immunologic diversity in thriving marine mammal species. The 172 bp sequences amplified show no more than two alleles in each individual. The high proportion of non-synonymous nucleotide substitutions and moderate amount of variation suggest positive selection pressure on this locus. The phylogenetic relationship among DQB exon 2 sequences of these two coastal species and other 3 pelagic delphinid species from the western Pacific does not coincide with taxonomic relationship, indicating habitatspecific allele existence resulting from pathogen-driven directional selection.

並列關鍵字

MHC ； DQB ； bottlenose dolphins ； delphinids ； western Pacific