Natural Selection Coupled With Intragenic Recombination Shapes Diversity Patterns in the Major Histocompatibility Complex Class II Genes of the Giant Panda
Natural Selection Coupled With Intragenic Recombination Shapes Diversity Patterns in the Major Histocompatibility Complex Class II Genes of the Giant Panda
复制标题
DOI：
10.1002/jez.b.21327
复制
发表时间：
2010-05-15
影响因子：
2.2
通讯作者：
Fang, Sheng-Guo
中科院分区：
文献类型：
--
作者：
Chen, Yi-Yan;Zhang, Ying-Ying;Fang, Sheng-Guo
主要组织相容性复合体（MHC）基因的丰富变异是脊椎动物适应各种环境条件所必需的。本研究对大熊猫7个MHC Ⅱ类功能基因（1个DRB、2个DQA、2个DQB）的遗传变异和进化模式进行了研究。结果表明，在该群体中存在2个单态位点（DRB 1和DQB 2）和5个多态位点（DRB 1 7个，DRB 3 6个，DQA 1 7个，DQA 2 4个，DQB 1 6个）。平衡选择在大熊猫中的存在得到以下证据的支持：（1）观察到的杂合度高于预期。(2)氨基酸杂合性显着较高的抗原结合位点（ABS）相比，非ABS序列。(3)与非ABS序列相比，ABS序列的选择参数omega（d（N）/d（S））显著更高。(4)约95.45%（P>0.95）的阳性选择密码子位于ABS或ABS附近。此外，本研究还表明：（1）秦岭亚种在每个位点上都表现出较高的Ω值（均>1），支持其广泛的正选择。(2)四川亚种在DRB 1处显示小的Ω（Ω
Ample variations of the major histocompatibility complex (MHC) genes are essential for vertebrates to adapt to various environmental conditions. In this study, we investigated the genetic variations and evolutionary patterns of seven functional MHC class II genes (one DRA, two DRB, two DQA, and two DQB) of the giant panda. The results showed the presence of two monomorphic loci (DRA and DQB2) and five polymorphic loci with different numbers of alleles (seven at DRB1, six at DRB3, seven at DQA1, four at DQA2, six at DQB1). The presence of balancing selection in the giant panda was supported by the following pieces of evidence: (1) The observed heterozygosity was higher than expected. (2) Amino acid heterozygosity was significantly higher at antigen-binding sites (ABS) compared with non-ABS sequences. (3) The selection parameter omega (d(N)/d(S)) was significantly higher at ABS compared with non-ABS sequences. (4) Approximately 95.45% of the positively selected codons (P>0.95) were located at or adjacent to an ABS. Furthermore, this study showed that (1) The Qinling subspecies exhibited high omega values across each locus (all >1), supporting its extensive positive selection. (2) The Sichuan subspecies displayed small omega at DRB1 (omega