Tetrodotoxin and paralytic shellfish toxins derived from RNA of marine bacteria

河豚毒素(TTX)和麻痹性贝类毒素(PSP)是具有相似药理活性的强效神经毒素。这两种毒素都是不同的毒素，化学结构不同，分布在不同的生物体中，所以不同的研究人员对它们进行了独立的研究。它们之间的相关性还没有得到讨论。另一方面，我们报道了河豚是一种典型的河豚毒素携带者，除了河豚毒素外，还含有PSP和TTX，这两种毒素都是通过核糖核酸酶消化从河豚肝脏的高分子部分释放出来的。这些事实表明，这两种毒素的产生都与某些生物体的RNA有关。研究表明，塔玛亚历山大藻是一种具有代表性的甲藻毒素产生菌，它同时具有TTX和PSP。最近，在一些细菌中发现了TTX和PSP。这些细菌包括在海水中常见的一种细菌，这表明大多数海洋生物都接触到了这些细菌。目前的研究表明，常见水生生物同时具有这两种毒素，但含量很低。据报道，细菌的产毒率很低。这一事实与普通动物体内的低水平毒素很好地吻合。Hawever说，它无法解释河豚等特定动物体内这些毒素的高含量，这表明某些未知的机制使特定动物中毒，例如特定动物与细菌合作产生毒素的机制。在有毒河豚的肝脏中发现了细菌共生。当用抗生素处理标本时，共生菌消失了。这些标本的肝脏无毒，表明肝脏中的共生生殖器参与了毒素的积累。虽然在电镜观察中没有观察到细胞内细菌，但其中一个细胞器被从塔玛乳杆菌分离的细菌的抗体染色。这也是一个阶段

Tetrodotoxin (TTX) and paralytic shellfish toxins (PSP) are potent neurotoxins with similar pharmacological activity. Both toxins have been studied by different researchers independently, because they are different toxins with different chemical structure which distribute in different organisms. No correlation between them has been discussed. On the other hand, we reported that puffer, a representative TTX-bearing animal, possesses PSP as well as TTX, and that both toxins are released from high molecular fraction of the liver of toxic puffer by RNase digestion. These facts suggest that both toxins occur correlatedly in association with RNA of some organism. The present study revealed that Alexandrium tamarense, a representative PSP producing dinoflagellate, possesses TTX as well as PSP.Recently, TTX and PSP have been identified in some bacterial strains. These bacteria include a species which can be commonly observed in the seawater, indicating that most of marine organisms are exposed to these bacteria. The present study showed that common aquatic organisms possess both toxins, thogh the level is very low. Toxin productibity of bacteria is reported to be very low. This fact coincides well with low level of toxin in common animals. Hawever, it could not explain the high amount of these toxins in specific animals such as puffer, suggesting that some unknown mechanism for the specific animals to be made toxic, for example, the toxin production mechanism by collaboration of the specific animals and bacteria. Symbiosis of bacteria was found in the liver of toxic puffer specimens. Symbiotic bacteria disappeared when the specimens were treated with antibiotics. The liver of these specimens belomes nontoxic, showing that symbiotic gacteria in the liver is involved in toxin accumulation. Although endocellular bacteria were not observed in A.tamarense by EM observation, one of the organella was stained by antibody against bacterium isolated from A.tamarense. It was also sta