Toll-like receptors (TLRs) are transmembrane proteins of the innate immune system, composed of the ectodomain involved in pathogen recognition and the intracellular Toll/interleukin-1 receptor (TIR) domain important for downstream signal transduction. Here, we analyze the genetic variability of TIR nucleotide and amino-acid sequences of the TLR2 gene in 243 brown hares from Europe and the Middle East and tested for the presence of selection signals and spatial structuring. TLR2 TIR domain sequences were PCR amplified and sequenced, while genotyping was performed by phasing. Genetic diversity indices were calculated in DnaSP and Arlequin, while presence of selection signals was tested using MEGA and the Datamonkey web server. The presence of spatial patterns in TIR sequence distribution was tested by spatial Principal Component Analysis (sPCA) in adegenet. A total of 13 haplotypes were revealed with haplotype diversity of 0.424, and nucleotide diversity (π) of 0.00138. Two spatial clusters were revealed: "Anatolia/Middle East" and "Europe". In Anatolia the two most prevalent amino-acid variants, A and B (the latter being the most ancestral) were maintained at similar frequencies; but in Europe a shift in genotype frequencies was observed as well as a higher number of nonsynonymous substitutions giving rise to novel amino-acid protein variants originating from the evolutionarily younger protein variant. Molecular diversity (haplotype and nucleotide diversity) indices were significantly higher in the "Anatolia/Middle East" cluster. A signal of purifying selection was detected acting on the TIR sequences.

中文翻译：

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纯化选择影响了来自欧洲和中东地区的棕色野兔（欧洲兔）中Toll样受体2 TIR结构域的进化。

Toll样受体（TLR）是先天免疫系统的跨膜蛋白，由参与病原体识别的胞外域和对下游信号转导很重要的细胞内Toll / IL-1受体（TIR）域组成。在这里，我们分析了来自欧洲和中东的243个棕色兔子中TLR2基因的TIR核苷酸和氨基酸序列的遗传变异性，并测试了选择信号的存在和空间结构。对TLR2 TIR结构域序列进行PCR扩增和测序，同时通过定相进行基因分型。在DnaSP和Arlequin中计算遗传多样性指数，同时使用MEGA和Datamonkey Web服务器测试选择信号的存在。通过adegenet中的空间主成分分析（sPCA）测试了TIR序列分布中空间模式的存在。揭示了总共13个单倍型，单倍型多样性为0.424，核苷酸多样性（π）为0.00138。揭示了两个空间群：“安那托利亚/中东”和“欧洲”。在安纳托利亚，两个最普遍的氨基酸变体A和B（后者是最祖先的）保持相似的频率。但是在欧洲，人们观察到基因型频率发生了变化，并且出现了更多的非同义词替换，从而产生了源自进化上更年轻的蛋白质变体的新型氨基酸蛋白质变体。在“ Anatolia /中东”集群中，分子多样性（单倍型和核苷酸多样性）指数明显更高。