太平洋亚历山大藻对凡纳滨对虾的急性毒性效应

Acute Toxic Effects of Alexandrium pacificum on Litopenaeus vannamei

【目的】研究太平洋亚历山大藻(Alexandrium pacificum)对凡纳滨对虾(Litopenaeus vannamei)的存活率、抗氧化能力以及组织结构的影响。【方法】采用浸浴法,将凡纳滨对虾暴露于太平洋亚历山大藻破碎液中72 h,检测肝胰腺中丙二醛(MDA)、谷胱甘肽(GSH)含量以及超氧化物歧化酶(SOD)、谷胱甘肽—S转移酶(GST)、碱性磷酸酶(AKP)、多酚氧化酶(PPO)等抗氧化酶的活力。对有毒藻浸浴处理和正常海水中对虾的肠道、肝胰腺、鳃、肌肉和神经组织的HE染色石蜡切片进行观察。【结果】太平洋亚历山大藻浸浴处理对凡纳滨对虾的存活率有显著影响(P<0.01)。与对照组相比,太平洋亚历山大藻会诱导对虾肝胰腺的MDA含量增加,导致肝胰腺发生脂质过氧化;同时,诱导GST、GSH、SOD、AKP和PPO的活力增强以清除多余氧自由基,抑制脂质过氧化作用。活性氧(ROS)过多会导致对虾氧化-抗氧化系统的平衡受损,72 h时,实验组对虾肝胰腺的GSH含量显著低于对照组(P<0.01),SOD、GST以及AKP活力也显著低于对照组(P<0.01)。石蜡切片观察发现,太平洋亚历山大藻引起了对虾肠道、肝胰腺、鳃、肌肉和神经组织细胞肿胀、空泡化等病理变化。【结论】急性暴露于太平洋亚历山大藻会引起对虾重要组织和器官病变,诱导对虾肝胰脏抗氧化酶的改变,这将有助于解释甲壳类动物在太平洋亚历山大藻胁迫下存在的解毒机制。

【Objective】To study the effects of Alexandrium pacificum on survival rate,antioxidant capacity and tissue structure of Litopenaeus vannamei.【Method】L.vannamei was immersed in the fluid of crushed A.pacificum for 72 hours,and the content of malondialdehyde(MDA)and glutathione(GSH),the activity of superoxide dismutase(SOD),glutathione S-transferase(GST),alkaline phosphatase(AKP)and polyphenol oxidase(PPO)in hepatopancreas were detected.The hematoxylin-eosin-stained paraffin sections of the intestines,hepatopancreas,gills,muscles and nerves of shrimps treated with toxic fluid of crushed A.pacificum and in normal seawater were observed.【Results】The survival rate of L.vannamei was significantly affected by the bath treatment of A.pacificum(P<0.01).Compared with the control group,A.pacificum induced the increase of MDA content in hepatopancreas,leading to lipid peroxidation in hepatopancreas.At the same time,the activities of GST,GSH,SOD,AKP and PPO were enhanced to remove excess oxygen free radicals and inhibit lipid peroxidation.Excessive reactive oxygen species(ROS)caused damage to the balance of oxidation-antioxidant system of prawn,at 72 h,the contents of GSH in hepatopancreas of the experimental group were significantly lower than those of the control group(P<0.01),SOD,GST and AKP activities were significantly lower than those of control group(P<0.01).Observation of paraffin sections revealed that A.pacificum caused pathological changes such as swelling and vacuolization of shrimp intestines,hepatopancreas,gills,muscle and nerve tissue cells.【Conclusion】Acute exposure to A.pacificum causes lesions in important tissues and organs of shrimp,and induces changes in the immune-related enzymes of the shrimp hepatopancreas,which will help to explain the detoxification mechanism of crustaceans under A.pacificum stress.