Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Faro, Portugal.
International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University (SHOU), Shanghai, China.
Front Immunol. 2022 Feb 14;13:812890. doi: 10.3389/fimmu.2022.812890. eCollection 2022.
Toll-like receptors (TLRs) recognize conserved pathogen-associated molecular patterns (PAMPs) and are an ancient and well-conserved group of pattern recognition receptors (PRRs). The isolation of the Antarctic continent and its unique teleost fish and microbiota prompted the present investigation into Tlr evolution. Gene homologues of members in teleosts from temperate regions were present in the genome of Antarctic Nototheniidae and the non-Antarctic sister lineage Bovichtidae. Overall, in Nototheniidae apart from , no major gene family expansion or contraction occurred. Instead, lineage and species-specific changes in the ectodomain and LRR of Tlrs occurred, particularly in the Tlr11 superfamily that is well represented in fish. Positive selective pressure and associated sequence modifications in the TLR ectodomain and within the leucine-rich repeats (LRR), important for pathogen recognition, occurred in Tlr5, Tlr8, Tlr13, Tlr21, Tlr22, and Tlr23 presumably associated with the unique Antarctic microbiota. Exposure to lipopolysaccharide ( O111:B4) Gram negative bacteria did not modify gene expression in head-kidney or anterior intestine, although increased water temperature (+4°C) had a significant effect.
Toll 样受体（TLRs）识别保守的病原体相关分子模式（PAMPs），是一种古老而高度保守的模式识别受体（PRRs）群体。南极洲的隔离及其独特的硬骨鱼和微生物群促使我们对 TLR 的进化进行了研究。在南极鳕鱼科和非南极姐妹鳕鱼科的基因组中存在来自温带地区硬骨鱼的 TLR 成员的基因同源物。总的来说，在鳕鱼科中，除了 之外，没有发生主要的 TLR 基因家族扩张或收缩。相反，TLRs 的胞外域和 LRR 发生了谱系和物种特异性的变化，特别是在鱼类中广泛存在的 TLR11 超家族。在 TLR 胞外域和富含亮氨酸重复序列（LRR）中，与病原体识别相关的正选择压力和相关的序列修饰发生在 TLR5、TLR8、TLR13、TLR21、TLR22 和 TLR23 中，这可能与独特的南极微生物群有关。尽管水温升高（+4°C）有显著影响，但脂多糖（O111:B4）革兰氏阴性菌的暴露并未改变头肾或前肠中的 基因表达。
