T-2毒素对凡纳滨对虾的经口急性毒性效应研究

Acute Oral Toxicity of T-2 Toxin on Litopenaeus Vannamei

摘要:

通过T-2毒素微胶囊毒饵料一次性染毒凡纳滨对虾，采用模型拟合法测定T-2毒素对凡纳滨对虾经口LD50，并分析Ca2+-ATPase、多酚氧化酶（PPO）活力以及肌肉病理组织学变化，进而探明T-2毒素对凡纳滨对虾急性毒性效应。结果表明，T-2毒素对凡纳滨对虾的急性毒性经口一次性暴露的LD50为1.22 mg/(kg?bw)，T-2毒素对PPO酶活性和Ca2+-ATPase活性的急性毒性效应ED50分别为0.05和3.22 mg/(kg?bw)，比较风险评估指数RI可知，PPO活性可作为生物学效应标记描述T-2毒素对对虾的急性毒性效应，且比Ca2+-ATPase更加灵敏。T-2毒素急性暴露可导致肌纤维间隙面积比增大，可导致对虾肌肉品质劣化。采用LC-MS/MS定量检测染毒对虾肌肉中的T-2毒素，但是没有发现游离态T-2毒素残留，说明对虾中T-2毒素急性暴露不会引起物质蓄积，但却产生功能蓄积，可能是T-2毒素以隐蔽态形式存在, 导致初始轻微损伤逐渐累加的结果。

Abstract:

Litopenaeus vannamei were orally administered as single-dose capsules containing the T-2 toxin (T-2), and the oral median lethal dose (LD50) of the T-2 toxin in Litopenaeus vannamei was determined using the model-fitting method. The Ca2+-ATPase and polyphenol oxidase (PPO) activities, as well as the histopathological changes in muscles were analyzed to explore the acute toxicity of T-2 on Litopenaeus vannamei. The results showed that the LD50 of T-2 via oral administration in a single dose was 1.22 mg/(kg?bw), and the medium effective dose (ED50) levels of Ca2+-ATPase and PPO activities were 0.05 and 3.22 mg/(kg?bw), respectively. According to the risk index (RI), the PPO activity can serve as a biological marker for the acute toxicity of T-2 on Litopenaeus vannamei and is more sensitive than Ca2+-ATPase. Acute T-2 exposure could lead to an increasing area ratio of the muscle fiber gap and shrimp quality deterioration. Quantitative analysis of T-2 in shrimp muscles was conducted by liquid chromatography-tandem mass spectrometry (LC-MS/MS); no free T-2 residues were found, indicating that acute T-2 exposure in shrimp could cause functional accumulation but not material accumulation. This was probably because T-2 was present in a masked form, which led to the gradual accumulation of minor damage during the initial stage.