日本囊对虾ML基因的克隆与表达分析

Cloning and Expression of a ML Superfamily Protein in Marsupenaeus japonicas

本研究克隆了日本囊对虾的1个ML基因——MjML,该基因的cDNA全长614 bp,开放阅读框长453 bp,编码150个氨基酸。MjML的基因组序列为1 678 bp,含有4个外显子3个内含子。MjML具有6个在ML蛋白中相对保守的半胱氨酸残基,可能形成3对二硫键。实时荧光定量PCR结果显示,MjML主要在肝胰腺中表达,其他组织中表达极微量。感染白斑综合症病毒(WSSV)后,MjML在肝胰腺中的表达量先上升后下降,于24 h出现显著上调,并达到最高峰值。在日本囊对虾早期幼体发育过程中,MjML表达量在阶段性的蜕皮变态后有大幅的升高;在仔虾期间,MjML表达量呈阶段上升特征。结果表明,MjML不仅可能与日本囊对虾先天性免疫应答相关,而且与其幼体发育过程中的变态及蜕皮也可能有一定的关联。

MD-2-related lipid-recognition （ML） superfamily proteins have a single ML domain, which can be bound to specific lipids and play important roles in innate immunity, lipid-recognition and metabolism. The cDNA and gene of a ML protein was identified form Marsupenaeus japonicus, and this ML protein was named as MjML. The full length cDNA of the MjML was 614 bp, with a 453 bp open reading frame that encoded 150 ami- no acid residues. The MjML gene was 1 678 bp in length, and consisted of four exons and three introns. The pu- tative MjML protein contained 6 cysteines which could form 3 pairs of disulfide bonds. Real-time quantitative PCR results showed that MjML mRNA was mainly highly expressed in the hepatopancreas, but very low in other examined tissues. After M. japonicus was challenged with white spot syndrome virus （WSSV）, the expression of MjML in hepatopancreas increased gradually and then decreased. At 24 h, the MjML was upregulated and its ex- pression reached the peak. During the early larval development of M. japonicus, especially after the metamorphosis, the MjML expression had a sharp rise. The MjML expression increased step by step at the post-larvae stage. The results showed that the MjML might play a role in the innate immunity of M. japonicus. And during the early larval development, the expression of MjML mRNA there might be correlated with the molting and meta- morphosis in shrimp larval development.