silp鱼(Hypophphichthysmolitrix)和big鱼(Hypophphichthysnobilis)的免疫防御功能已显示出明显的进化差异。miRNA参与免疫功能的精细调节。然而,miRNAs在调节免疫防御功能中的进化适应在silver鱼和big鱼中仍然知之甚少。这里,从一岁和三岁健康的silver鱼和big鱼的脾脏组织中构建小RNA文库,通过生物信息学分析,分别从鲤鱼和big鱼的脾脏中鉴定出424和422个已知的保守miRNA,其中398个是两个物种共有的。这些保守的miRNAs在银鲤鱼和big鱼之间显示出高度相似的表达模式,但是不同物种的脾脏丰度差异很大。家族分析表明,mir-8,mir-7,mir-23,mir-338,mir-30,mir-27,mir-221,mir-19,mir-181,mir-17,mir-15,mir-148,mir-130,mir-10和let-7等miRNA家族是silver鱼和big鱼脾脏中的主要miRNA。27和51个显著差异表达(SDE)的miRNA从银鲤鱼和bighead鱼,分别。对SDE-miRNAs预测的靶基因的进化分析显示,整合素介导的细胞粘附和适应性免疫应答被阳性选择。此外,免疫基因包括TLR3、NFATC3、MALT1、B2M、GILT和MHCII仅在鲤鱼中呈阳性选择,它们被SDE-miRNA特别靶向,包括miR-9-5p,miR-196a-5p,miR-375,miR-122,miR-722,miR-132-3p,miR-727-5p,miR-724、miR-19d-5p和miR-138-5p,分别。FcεRI信号通路中的PLA2G4仅在比目鱼中被阳性选择,并且被包括miR-222b在内的SDE-miRNA特异性靶向,miR-22b-5p,miR-15c,miR-146a,miR-125c-3p,miR-221-5p,miR-2188-5p,miR-142a-3p,miR-212、miR-138-5p和miR-15b-5p。特别是,SDE-miRNA,如miR-144-3p,miR-2188-3p,miR-731、miR-363-3p和miR-218b可同时靶向多个进化分化的免疫相关基因。这些结果表明,在silver鱼和big鱼的脾脏中,保守的miRNA在调节免疫防御功能方面具有明显的进化适应性。本研究结果可为进一步揭示miRNA在siling鱼和big鱼抗性性状进化形成中的作用机制提供有价值的资源。
Immune defense functions of silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) have shown obvious evolutionary divergence. MiRNAs participate in the fine regulation of immune function. However, the evolutionary adaptation of miRNAs in the regulation of immune defense function is still poorly understood in silver carp and bighead carp. Here, small RNA libraries were constructed from the spleen tissue of one-year-old and three-year-old healthy silver carp and bighead carp, 424 and 422 known conserved miRNAs were respectively identified from the spleen of silver carp and bighead carp by bioinformatic analysis, which 398 were shared between the two species. These conserved miRNAs showed highly similar expression patterns between silver carp and bighead carp, but the abundance in spleen varied greatly in different species. Family analysis showed that miRNA families including mir-8, mir-7, mir-23, mir-338, mir-30, mir-27, mir-221, mir-19, mir-181, mir-17, mir-15, mir-148, mir-130, mir-10 and let-7 were the main miRNAs in the spleen of silver carp and bighead carp. 27 and 51 significant differentially expressed (SDE) miRNAs were identified from silver carp and bighead carp, respectively. Evolution analysis for the predicted target genes of SDE-miRNAs showed that ten biological processes such as blood coagulation, cell adhesion mediated by integrin and adaptive immune response were positively selected. In addition, immune genes including TLR3, NFATC3, MALT1, B2M, GILT and MHCII were positively selected only in silver carp, and they were specifically targeted by the SDE-miRNAs including miR-9-5p, miR-196a-5p, miR-375, miR-122, miR-722, miR-132-3p, miR-727-5p, miR-724, miR-19d-5p and miR-138-5p, respectively. PLA2G4 in Fc epsilon RI signaling pathway was positively selected only in bighead carp and was specifically targeted by the SDE-miRNAs including miR-222b, miR-22b-5p, miR-15c, miR-146a, miR-125c-3p, miR-221-5p, miR-2188-5p, miR-142a-3p, miR-212, miR-138-5p and miR-15b-5p. In particular, SDE-miRNAs such as miR-144-3p, miR-2188-3p, miR-731, miR-363-3p and miR-218b could simultaneously target multiple evolutionarily differentiated immune-related genes. These results indicated that in the spleen of silver carp and bighead carp, conserved miRNAs have obvious evolutionary adaptations in the regulation of immune defense function. The results of this study can provide valuable resources for further revealing themechanism of miRNA in the formation of resistance traits evolution between silver carp and bighead carp.