凡纳滨对虾在微囊藻毒素(MC-LR)诱导下3种抗菌肽基因的表达量分析

蓝藻水华可产生大量藻毒素,其中以微囊藻毒素危害最大。研究表明微囊藻毒素可影响包括虾类在内的多种水生生物的生长和繁殖,亦可导致虾类免疫系统受损。本研究通过实时荧光定量PCR(qRT-PCR)技术检测了在微囊藻毒素MC-LR作用下,凡纳滨对虾(Litopenaeus vannamei)体液免疫中3种主要的抗菌肽基因(Penaeidin 3、Crustin和ALF)的表达量变化情况,发现Penaeidin 3和ALF受到MC-LR影响较大,Crustin基因表达量虽有所上调,但变化不大。同时,通过再次注射鳗弧菌(Vibrio anguillarum)对3种抗菌肽在MC-LR影响下抗菌能力的检测,发现3种抗菌肽表现出相对一致的变化,即表达量均在前期下调,4 h后逐渐上调,在MC-LR处理组中的表达量低于对照组的趋势。结果表明MC-LR可能通过直接或间接的方式影响对虾3种抗菌肽基因的表达,对免疫系统造成损伤,致使对虾抗病能力减弱;这一结果表明,长期发生铜绿微囊藻水华的虾池对虾存活率下降,可能与微囊藻毒素影响对虾抗菌肽基因的表达有关。

Expression profiles of three antimicrobial peptide genes in Litopenaeus vannamei induced by microcystin (MC-LR)

Microcystins (MCs) are a kind of cyanobacterial toxins produced by cyanobacterial bloom. They can affect the growth and reproduction of a variety of aquatic organisms, such as shrimp. In this study, the expression profiles of three antimicrobial peptide genes (Penaeidin 3, Crustin and ALF) in Litopenaeus vannamei were detected via real-time fluorescent quantitative PCR (qRT-PCR) method post MC-LR injection. The results show that MCs can significantly affect the expression of Penaeidin 3 and ALF but cannot affect that of Crustin. In order to understand the impact of MC-LR on the response of the three peptides to bacteria, Vibrio anguillarum was injected into the shrimps after MC-LR injection. The relative expressions of three antimicrobial peptide genes were all down-regulated in the early stage and up-regulated after 4 h post Vibrio anguillarum challenge. Expressions of three genes in MC-LR injected group were all down-regulated compared with the control group. The results suggest that MC-LR could affect the expressions of antimicrobial peptide genes in unkown ways and impact the shrimp immune system; meanwhile, the results hinted that the low survival rate of shrimps exposed to Microcystis blooms ponds in a long period may be related to the impacts of MCs on the shrimp antibacterial peptides.