摘要
克隆了乌骨鸡(BF2*SI)和珍珠鸡(BF2*NM)群主要组织相容性复合体I(MHC class I)和β微球蛋白(β2m)基因,分析了其分子特征与等位基因多态性。BF2*SI相互间氨基酸同源率为75.5%~93.9%,保留了人HLA-A2与抗原多肽结合的7个关键性氨基酸。BF2*NM相互间氨基酸同源率为81.1%~98.5%,保留了人HLA-A2与抗原多肽结合的6个关键性氨基酸。BF2*SI在α1和α2区(抗原多肽结合区,PBD)有24个高置换率位点,置换率最高的为69位和9位。BF2*NM在PBD区共有6个高置换率位点。BF2*SIPBD发生氨基酸置换的位点数大于来航鸡BF2,BF2*NMPBD区氨基酸置换的位点数和置换率则远远小于来航鸡BF2。根据同源率,将BF2*SIα1区分为4类,α2区分为3类,α3区分为3类,并由此聚类为5个系谱(A^E)。将BF2*NMα1区分为3类,α2区分为3类,α3区分为1类,并由此聚类为3个系谱(A^C)。比较发现BF2*03SI、BF2*04SI和BF2*05NM的α1区与抗马立克氏病的BF2*21同源率最高(分别为86.4%、86.4%和87.5%);BF2*05SI和BF2*05NM的α2区与BF2*21同源率最高(均为93.4%)。另外,根据成熟肽区的氨基酸序列可将乌骨、珍珠鸡β2m分为两类,第一类和来航鸡β2m(M84767)氨基酸序列完全相同,第二类与第一类相比,氨基酸序列相互间同源率为85.7%。结果揭示了各类鸡的MHCⅠ和β2m基因具有品种分子特征。
The major expressed MHC class I and beta 2-microglobulin (β2m) genes were cloned from a silky chicken breed and Numida Meleagris breed (the MHC class I genes were designated BF2 * SI and BF2 * NM , respectively ). The allelic polymorphisms in the population of the two chicken breeds were investigated. The amino acids homologies among BF2 * SI, BF2 * NM alleles were 75.5%-93.9% and 81.1%-98.5%, respectively. Compared with human HLA-A2, seven of key amino acids of the peptide binding sites were conserved in BF2 * SI, but six in BF2 * NM. Twenty-four high amino acids substitution sites (amino acids substitutions ratio≥4.0) were found in the peptide-binding domain (PBD) of BF2 * SI , and two sites (position 69 and 9) displayed the amino acids substitutions ratio≥8.0. Unlike BF2 * SI, only six high amino acids substitution sites were found in the PBD of BF2 * NM. The numbers of high amino acids substitution sites in PBD of Leghorn chicken BF2 was lower than that of BF2 * SI, but higher than that of BF2 * NM. According to homology ratios, α1, α2, α3 of BF2 * SI were classed into 4, 3 and 3 types, and α1, α2, α3 of BF2 * NM were classed into 3, 3 and 1 types, respectively. Six BF2 * SI genes were subdivided to 5 lineages (A, B, C, D and E), whereas five BF2 * NM genes were subdivided to 3 lineages (A, B, C). Comparison the amino acids homology ratios of α1, α2 domains in BF2 * SI, BF2 * NM with that in BF2 * 21 with resistance to MDV revealed that BF2 * 03SI, BF2 * 04SI, BF2 * 05NM were most similar to BF2 * 21 in α1 domains (with homology ratios of 86.40%, 86.4%, 87.5%, respectively), and BF2 * 05SI, BF2 * 05NM were most similar to BF2 * 21 in α2 domains (with homology ratios of both 93.4 %). The β2m genes of silky chicken breed and Numida Meleagris breed could be classed into 2 types (type 1 ,type 2) based on the amino acids sequences of mature peptides. The type 1 was identical to the β2m genes of Leghorn chicken(accession number M84767) , but type 2 only had the homology ratio of 87.5 % with type 1. The results suggested that the BF2 and β2m genes of each chicken breed own its special molecular characters.
出处
《畜牧兽医学报》
CAS
CSCD
北大核心
2005年第9期861-868,共8页
ACTA VETERINARIA ET ZOOTECHNICA SINICA
基金
国家自然科学基金项目(30371098)