Table_1_Characterization of TLR1 and expression profiling of TLR signaling pathway related genes in response to Aeromonas hydrophila challenge in hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × P. vachelli ♂).docx

Toll‐like receptor 1 (TLR1) mediates the innate immune response to a variety of microbes through recognizing cell wall components (such as bacterial lipoproteins) in mammals. However, the detailed molecular mechanism of TLR1 involved in pathogen immunity in the representative hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × P. vachelli ♂) has not been well studied. In the present study, we identified the TLR1 gene from the hybrid yellow catfish, and further comparative synteny data from multiple species confirmed that the TLR1 gene is highly conserved in teleosts. Phylogenetic analysis revealed distinguishable TLR1s in diverse taxa, suggesting consistence in evolution of the TLR1 proteins with various species. Structural prediction indicated that the three-dimensional structures of TLR1 proteins are relatively conserved among different taxa. Positive selection analysis showed that purifying selection dominated the evolutionary process of TLR1s and TLR1-TIR domain in both vertebrates and invertebrates. Expression pattern analysis based on the tissue distribution showed that TLR1 mainly transcribed in the gonad, gallbladder and kidney, and the mRNA levels of TLR1 in kidney were remarkably up-regulated after Aeromonas hydrophila stimulation, indicating that TLR1 participates in the inflammatory responses to exogenous pathogen infection in hybrid yellow catfish. Homologous sequence alignment and chromosomal location indicated that the TLR signaling pathway is very conserved in the hybrid yellow catfish. The expression patterns of TLR signaling pathway related genes (TLR1- TLR2 - MyD88 - FADD - Caspase 8) were consistent after pathogen stimulation, revealing that the TLR signaling pathway is triggered and activated after A. hydrophila infection. Our findings will lay a solid foundation for better understanding the immune roles of TLR1 in teleosts, as well as provide basic data for developing strategies to control disease outbreak in hybrid yellow catfish.

Toll 样受体 1 (TLR1) 通过识别哺乳动物细胞壁成分（如细菌脂蛋白）介导对多种微生物的先天免疫反应。然而，在代表性杂交黄颡鱼（Pelteobagrus fulvidraco ♀ × P. vachelli ♂）中，TLR1 在病原体免疫中所涉及的详细分子机制尚未得到充分研究。在本研究中，我们鉴定了杂交黄颡鱼的 TLR1 基因，并通过来自多个物种的比较同源数据进一步证实了 TLR1 基因在辐鳍鱼类中的高度保守性。系统发育分析揭示了不同分类群中可区分的 TLR1，表明 TLR1 蛋白在物种演化过程中与各种物种保持一致性。结构预测表明，TLR1 蛋白的立体结构在不同分类群中相对保守。正向选择分析显示，净化选择在脊椎动物和无脊椎动物的 TLR1s 和 TLR1-TIR 结构域的进化过程中占据主导地位。基于组织分布的表达模式分析表明，TLR1 主要在性腺、胆囊和肾脏中转录，且在嗜水气单胞菌刺激后，肾脏中 TLR1 的 mRNA 水平显著上调，这表明 TLR1 参与杂交黄颡鱼对外源病原体感染引起的炎症反应。同源序列比对和染色体定位表明，杂交黄颡鱼中的 TLR 信号通路高度保守。TLR 信号通路相关基因（TLR1- TLR2- MyD88- FADD- Caspase 8）的表达模式在病原体刺激后保持一致，揭示了 TLR 信号通路在嗜水气单胞菌感染后被触发和激活。我们的研究结果将为更深入理解 TLR1 在辐鳍鱼类免疫中的作用奠定坚实基础，并为开发控制杂交黄颡鱼疾病暴发的策略提供基本数据。