Studies on metabolisms of paralytic shellfish toxins in scallop in association with the reductive transformation by thiols

扇贝中麻痹性贝类毒素代谢与硫醇还原转化的研究

基本信息

批准号：
13660207
负责人：
SATO Shigeru
金额：
$ 2.11万
依托单位：
Kitasato University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Paralytic shellfish poisoning caused by toxic dinoflagellates such as Alexandrium spp. is the most prominent shell poison because of acuteness of the symptoms and high fatality. Once contaminated by paralytic shellfish toxins, it takes a time to depurate toxins in bivalves. A long-time closure of the shellfish market due to this phenomenon poses severe damage to the shellfish industry. However, no effective method to remove paralytic shellfish toxins from bivalves have been developed, because there is little knowledge about the metabolism of the toxins. Gonyautoxins (GTXs), 11-O-sulfate derivatives of STX, are major components of Alexandrium spp. which distribute in northern Pacific area. Toxin profile of the shellfish during a bloom of toxic dinoflagellates reflects that of the causative dinoflagellate. In the toxin deputation period after disappearance of the causative dinoflagellates, however, toxin profile of the shellfish gradually changes, for example, a part of GTXs transforms to STXs, though the biological process of transformation has not been elucidated. Recently, we have found that bacterial extracts transform GTXs to STXs. In this transformation, glutathione (GSH) in the extract is found to be involved. A stable conjugate of GSH and STXs is formed in a process of the reaction. These findings suggest that GSH in the shellfish tissue is involved in the transformation of GTXs to STXs of the shellfish during deputation period, and that GS-STXs conjugates are formed and accumulated in the shellfish. However, the conjugates were not detected in the tonic shellfish, suggesting that something happens on the conjugates. In this study, we demonstrate that STXs moiety of the GS-STXs conjugates are decomposed when glutamic acid residue is released by g-glutamyltranspeptidase, indicating that GSH is involved also in decomposition of GTXs accumulated in the shellfish.

由有毒鞭毛藻（例如Alexandrium spp）引起的麻痹贝类中毒。由于症状的敏锐度和死亡人数高，是最突出的壳毒。一旦被瘫痪的贝类毒素污染，将需要一些时间才能在双壳类中降低毒素。由于这种现象，贝类市场的长期关闭对贝类行业造成了严重破坏。但是，没有开发出从双壳类中去除麻痹性贝类毒素的有效方法，因为对毒素的代谢知识很少。 gonyautoxins（GTXS），STX的11-O-硫酸盐衍生物是Alexandrium spp的主要成分。在北太平洋地区分发。贝类的毒素特征在一大堆有毒的鞭毛藻植物中反映了鞭毛鞭毛酸酯的毒素。然而，在因果性鞭毛藻消失后的毒素代表时期，贝类的毒素谱逐渐变化，例如，GTXS的一部分转换为STX，尽管尚未阐明生物学转化过程。最近，我们发现细菌提取物将GTXS转化为STX。在这种转换中，提取物中的谷胱甘肽（GSH）被发现涉及。在反应过程中形成了GSH和STX的稳定共轭物。这些发现表明，贝类组织中的GSH参与了代表期间GTX向贝类的STX的转化，并且在贝类中形成并积累了GS-STXS结合物。但是，在补品贝类中未检测到缀合物，这表明在缀合物上发生了一些事情。在这项研究中，我们证明了GS-STXS结合物的STX部分是在G-Glutamylylanspeptidase释放出谷氨酸残基时分解的，这表明GSH也参与了在贝类中积累的GTX的分解。