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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.

由有毒甲藻（如亚历山大藻）引起的麻痹性贝类中毒。是最突出的贝毒，因为症状剧烈且死亡率高。一旦被麻痹性贝类毒素污染，双壳类体内的毒素需要一段时间才能净化。这种现象导致贝类市场长期关闭，对贝类产业造成严重损害。然而，由于对毒素代谢知之甚少，因此尚未开发出有效的方法来去除双壳类中的麻痹性贝类毒素。膝沟藻毒素 (GTX) 是 STX 的 11-O-硫酸盐衍生物，是亚历山大藻属的主要成分。分布于北太平洋地区。有毒甲藻大量繁殖期间贝类的毒素特征反映了致病甲藻的毒素特征。然而，在致病甲藻消失后的毒素释放期，贝类的毒素谱逐渐发生变化，例如部分GTX转化为STX，尽管转化的生物学过程尚未阐明。最近，我们发现细菌提取物将 GTX 转化为 STX。提取物中的谷胱甘肽 (GSH) 参与了这一转化。反应过程中形成GSH和STXs的稳定结合物。这些结果表明，贝类组织中的GSH参与了贝类在发育期间GTXs向STXs的转化，并且GS-STXs缀合物在贝类中形成和积累。然而，在补品贝类中没有检测到结合物，这表明结合物发生了一些变化。在这项研究中，我们证明，当谷氨酰转肽酶释放谷氨酸残基时，GS-STXs 缀合物的 STXs 部分被分解，表明 GSH 也参与了贝类中积累的 GTXs 的分解。