Department of Animal Behaviour, Bielefeld University, 33501, Bielefeld, Germany.
Department of Behavioural Ecology, Bielefeld University, 33501, Bielefeld, Germany.
Sci Rep. 2022 Oct 26;12(1):17933. doi: 10.1038/s41598-022-21658-7.
The major histocompatibility complex (MHC) is a group of genes comprising one of the most important components of the vertebrate immune system. Consequently, there has been much interest in characterising MHC variation and its relationship with fitness in a variety of species. Due to the exceptional polymorphism of MHC genes, careful PCR primer design is crucial for capturing all of the allelic variation present in a given species. We therefore developed intronic primers to amplify the full-length 267 bp protein-coding sequence of the MHC class II DQB exon 2 in the Antarctic fur seal. We then characterised patterns of MHC variation among mother-offspring pairs from two breeding colonies and detected 19 alleles among 771 clone sequences from 56 individuals. The distribution of alleles within and among individuals was consistent with a single-copy, classical DQB locus showing Mendelian inheritance. Amino acid similarity at the MHC was significantly associated with genome-wide relatedness, but no relationship was found between MHC heterozygosity and genome-wide heterozygosity. Finally, allelic diversity was several times higher than reported by a previous study based on partial exon sequences. This difference appears to be related to allele-specific amplification bias, implying that primer design can strongly impact the inference of MHC diversity.
主要组织相容性复合体 (MHC) 是一组基因，是脊椎动物免疫系统最重要的组成部分之一。因此，人们对 MHC 变异及其与适应性的关系在各种物种中的特征有很大的兴趣。由于 MHC 基因的特殊多态性，精心设计 PCR 引物对于捕获给定物种中存在的所有等位基因变异至关重要。因此，我们开发了内含子引物来扩增南极软毛海豹 MHC 类 II DQB 外显子 2 的全长 267bp 蛋白质编码序列。然后，我们对来自两个繁殖群体的母子对的 MHC 变异模式进行了特征描述，并在 56 个个体的 771 个克隆序列中检测到了 19 个等位基因。个体内和个体间的等位基因分布与单拷贝、经典的 DQB 基因座一致，表现出孟德尔遗传。MHC 中的氨基酸相似性与全基因组相关性显著相关，但 MHC 杂合度与全基因组杂合度之间没有关系。最后，等位基因多样性比之前基于部分外显子序列的研究报道要高几倍。这种差异似乎与等位基因特异性扩增偏倚有关，这意味着引物设计会强烈影响 MHC 多样性的推断。
