曼氏无针乌贼维甲酸X受体(RXR)cDNA的克隆与表达

维甲酸 X 受体(retinoid X receptor, RXR)属于配体激活的核受体家族。本研究采用 RT-qPCR 技术克隆了曼氏无针乌贼 RXR (SjRXR)基因的 CDS 区核酸序列, 推导出其氨基酸序列, 并对 RXR 基因 CDS 区核苷酸序列与蛋白质结构进行了生物信息学分析, 结果如下: SjRXR 的 CDS 区核苷酸序列全长 1239 bp, 编码 1 个由 412 个氨基酸组成的蛋白质; 序列分析表明, 曼氏无针乌贼 RXR 的 CDS 区基因编码的蛋白质不含有信号肽, 无跨膜结构, 推测 RXR 编码蛋白属于非分泌型、非跨膜蛋白; 对蛋白进行疏水性分析, 发现亲水性部分大于疏水性部分, 预测 RXR 编码蛋白为亲水性蛋白, 包含 1 个 HOLl 家族的结构域; 利用 MEGA 6.0 软件以 ML 法构建了系统进化树, 结果表明, 曼氏无针乌贼与双斑蛸亲缘关系最近, 同属于软体动物门头足纲, 最先聚为一支, 曼氏无针乌贼 RXR 基因的分子进化地位与其生物学分类地位大体保持一致。采用 RT-qPCR 技术分析了该基因在乌贼 4 个时期 11 个组织中的表达规律, 结果如下: sjRXR 基因在各组织中均有表达, 且在肝、胰、脑、视叶和视腺中表达量较高; sjRXR 基因表达在不同生长周期存在明显变化, 在肝、胰中呈一直上升趋势, 在脑、视叶、视腺中呈先上升后下降趋势。SjRXR 是曼氏无针乌贼神经发育、生殖调节和衰老凋亡的重要调控因子之一, 本研究结果可为进一步深入研究头足类动物 RXR 基因提供重要参考依据。

Cloning of the sjRXR gene and analysis of its distribution in developmental stages of Sepiella japonica

Retinoid X receptor (RXR) belongs to the family of nuclear receptors activated by ligands. In this study, the cDNA sequence of the Sepiella japonica RXR gene was cloned using RT-qPCR; bioinformatics analysis was conducted on the sequence of nucleotide and protein structure in the CDS region of the RXR gene. The results showed that the CDS-domain nucleotide sequence of SjRXR was 1239 bp, encoding a protein composed of 412 amino acids. Moreover, the sequence analysis showed that the CDS region of the S. japonica RXR gene did not contain a signal peptide, possibly indicating that the RXR encoding protein was a non-secretory protein. There is no transmembrane structure in the protein structure, making it a non-transmembrane protein. Hydrophobicity analysis shows that the protein is more hydrophilic than hydrophobic. It also contains a domain of the HOLl family. The phylogenetic tree was constructed using the MEGA6 software employing the ML method. S. japonica is closely related to Octopus bimaculatus, which belongs to the phylum Cephalopoda, gathered into one branch. Thus the molecular evolutionary status of the RXR gene of S. japonica is consistent with its biological classification status. RT-qPCR was also used to analyze the expression characteristics of this gene in eleven tissues of S. japonica during four growth periods. The sjRXR gene was expressed in all tissues, and it was highly expressed in the liver, pancreas, brain, visual lobe, and visual gland. The sjRXR expression changed significantly during the four growth stages, increased in the liver, pancreas, brain, optic lobe, and optic gland, but was followed by a decreasing trend in the brain, optic lobe, and optic gland. These results speculate that SjRXR regulates S. japonica neurodevelopment, reproduction, and aging as an essential factor and provide a vital reference base for in-depth study of the RXR gene in cephalopods.