第三十七卷(2008)
77.山羊DQA2 胺基酸序列之變異
廖仁寶 陳若菁 陳美如 黃鈺嘉 吳明哲
行政院農業委員會畜產試驗所
由15隻分屬五種山羊品種（阿爾拜因2頭；波爾5頭；努比亞4頭；吐根堡2頭；撒能2頭）之山羊樣品，進行DQA2 基因之選殖研究，結果共選殖出46個株系。經DNA 定序與胺基酸序列之分析後，此46 個株系可區分出24種不同之交替基因，並產生20種不同之胺基酸序列。由相同山羊樣品產生之不同株系之DNA 序列分析可得知，一個山羊樣品最多含有四種交替基因，因此在山羊之基因組中可能含有兩個DQA2 基因座。在DQA2 α1 domain 胺基酸序列的分析中得知，48.8% (40/82) 的胺基酸是具有多態性的，同時，在預測的抗原結合區中，73.7% (14/19) 的胺基酸具多態性。最具多態性的的位置分別為α14 (N, D, T, E, V), α34 (R, E, L, M), α53 (E, Q, R, H), α55 (R, T, I, A), α79 (R, L, C, H, W) ，除α34外，其他位點都包含於預測的抗原結合區中。因DQA2 為動物的免疫基因，因此序列具有ਢ度的多態性，此種多態性與疾病的抗性是否有關，則需進一步研究。
關鍵語：DQA2 基因、選殖、多態性
AMINO ACID SEQUENCE VARIATION OF DQA2 IN GOATS
R. B. Liaw, J. C. Chen, M. R. Chen, Y. C. Huang and M. C. Wu
Livestock Research Institute, Council of Agriculture, Executive Yuan
The DQA2 genes were cloned from 15 goats which belonged to 5 breeds including Alpine (2), Boer (5), Nubian (4), Toggenburg (2), and Saanen (2). A total of 46 cloneswere obtained from cloning procedure. According to the analyses of DNA sequencingand amino acid sequences of DQA2, 24 allele were discriminated from 46 clones and 20 kinds of amino sequences were deduced. There were at most 4 allele in one goat sampleafter the DNA sequence analyses from several clones. Therefore, there might be 2 DQA2 loci within the goat genome. In the amino acid sequence analysis of DQA2 α1 domain, 48.8% (40/82) of the sites were polymorphic; besides, 73.7% (14/19) of amino acids in the putative antigen-binding region were polymorphic. The most polymorphic sites were observed at α14 (N, D, T, E, V), α34 (R, E, L, M), α53 (E, Q, R, H), α 55 (R, T, I, A), and α79 (R, L, C, H, W), which are all included in the putative antigen-binding region except α34. Because DQA2 genes are responsible for immune reaction in animals, they possess highly polymorphisms. Whether or not the polymorphisms relate to disease resistance, the study needs to be conducted in the future.
Key Words: DQA2 gene, Cloning, Polymorphism
  
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