Wang Zeng, Zhou Xiaoping, Lin Qingxian, Fang Wenzhen, Chen Xiaolin
Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, People's Republic of China.
PLoS One. 2017 May 3;12(5):e0176671. doi: 10.1371/journal.pone.0176671. eCollection 2017.
The genes of major histocompatibility complex (MHC) are important to vertebrate immune system. In this study, two new MHC class I genes, designated as Egeu-UAA and Egeu-UBA, were discovered in the vulnerable Chinese egret (Egretta eulophotes). Using a full length DNA and cDNA produced by PCR and RACE methods, these two MHC class I loci were characterized in the genome of the Chinese egret and were also found to be expressed in liver and blood. Both new genes showed the expected eight exons and were similar to two copies of the minimal essential MHC complex of chicken. In genetic diversity, 14 alleles (8 for UAA and 6 for UBA) in the MHC class I gene exon 3 were found in 60 individuals using locus-specific primers and showed little polymorphism. Only three potential amino acid residues were detected under positive selection in potential peptide-binding regions (PBRs) by Bayesian analysis. These new results provide the fundamental basis for further studies to elucidate the molecular mechanisms and significance of MHC molecular adaptation in vulnerable Chinese egret and other ardeids, finding that have not been previously reported.
主要组织相容性复合体（MHC）基因对脊椎动物免疫系统至关重要。在本研究中，在濒危物种黄嘴白鹭（Egretta eulophotes）中发现了两个新的MHC I类基因，命名为Egeu-UAA和Egeu-UBA。利用PCR和RACE方法产生的全长DNA和cDNA，对这两个MHC I类基因座进行了黄嘴白鹭基因组特征分析，并且发现它们在肝脏和血液中表达。这两个新基因均显示出预期的八个外显子，并且与鸡的最小必需MHC复合体的两个拷贝相似。在遗传多样性方面，使用基因座特异性引物在60个个体中发现了MHC I类基因外显子3中的14个等位基因（UAA有8个，UBA有6个），且显示出很少的多态性。通过贝叶斯分析，在潜在肽结合区域（PBR）中仅检测到三个处于正选择下的潜在氨基酸残基。这些新结果为进一步研究阐明濒危黄嘴白鹭和其他鹭科鸟类中MHC分子适应性的分子机制及意义提供了基础，这些发现此前尚未见报道。
