血细胞吞噬参与拟穴青蟹免疫致敏及其分子作用机制

The memory of immunity in invertebrates is a controversal question as they lack an acquired adaptive immune system and host defense is believed to depend entirely on innate, non-adaptive mechanisms to resist invasion by pathogens. Mud crab Scylla paramamosain, is one of most important commercial maricultures in the southeast China. However, the frequent outbreaks of aquatic diseases extremely discourage the sustainable development of the mud crab aquaculture. Previous studies in our group showed that immune priming existed in the mud crabs when the crabs came across Vibro parahaemolyticus infection in a second time and further study suggested that the hemocytes subgroups which functioned in phagocytosis played a very important role in the crabs' immune priming. The project would focus on the immune primed mud crabs and studied the molecular mechanisms of the immune priming of the crabs by means of the morphologic and patholigical study of the phagocytic hemocyte subgroups, the expression profiles of cDNA transcriptome and miRNAs of hemocytes in primed and non-primed crabs by microarrays, the degradome sequencing to know the target genes of these significantly differentially expressed miRNAs and miRNAs' target genes. The project would give us a further knowledge of the molecular mechanisms of immune priming in the crab Scylla paramamosain through the heamocyte morphology, the study of transcription and post-transcription. The study would also be useful to enrich the theroies of immune priming in invertebrates, and to prevent the crab diseases by immunogical means and a positive effect on high intensity and high quality mud crab aquaculture in the future.

无脊椎动物是否有免疫记忆一直是一个有争议的话题。课题组前期研究表明，拟穴青蟹对病原菌副溶血弧菌的刺激存在"免疫致敏"，即免疫记忆现象。进一步研究发现，血细胞吞噬被封闭后青蟹的免疫致敏消失。本课题拟以免疫致敏状态的拟穴青蟹为研究对象，观察吞噬过程细胞亚群的形态变化及吞噬后细胞的病理学变化，并分离该细胞亚群进行活性检测。项目进一步制备cDNA和miRNA芯片，研究青蟹免疫致敏及吞噬被封闭免疫致敏消失时的基因表达谱和差异miRNAs。在此基础上，对差异表达基因进行功能鉴定和通路分析；对差异miRNAs则利用降解组测序研究其靶基因，从而从血细胞形态，转录及转录后水平研究青蟹免疫致敏及吞噬参与免疫致敏的分子机制。项目将深入了解血细胞吞噬参与青蟹免疫致敏的具体过程，揭示拟穴青蟹免疫致敏的分子机制。研究可以丰富无脊椎动物免疫致敏的理论基础，在实践上对控制青蟹病害的发生，开发新的防治方法等具有指导意义。

无脊椎动物是否有免疫记忆一直是一个有争议的话题。课题组前期研究表明，拟穴青蟹对病原菌副溶血弧菌的刺激存在“免疫致敏”，即免疫记忆现象。进一步研究发现，血细胞吞噬被封闭后青蟹的免疫致敏消失。在国家基金的支持下，项目组以免疫致敏状态的拟穴青蟹为研究对象，获得了如下成果：1）观察了吞噬过程血细胞亚群的形态变化及吞噬过程；2）系统研究了吞噬过程中起作用的关键基因，研究了吞噬相关基因（SRB，C-type Lectin， cSP等）的功能及涉及的代谢通路；3）研究了青蟹免疫致敏及吞噬被封闭免疫致敏消失时的基因表达谱和差异miRNAs。4）研究了青蟹中特异的益生菌，对益生菌的益生效果及益生机理进行了初步的研究。项目组从细胞形态观察，候选基因研究，差异基因（或miRNA）表达，益生菌等方面研究了青蟹免疫致敏及吞噬参与免疫致敏的分子机制。项目对深入了解血细胞吞噬参与青蟹免疫致敏的具体过程，揭示拟穴青蟹免疫致敏的分子机制具有积极意义。研究可以丰富无脊椎动物免疫致敏的理论基础，在实践上对控制青蟹病害的发生，开发新的防治方法等具有指导意义。