Tetrodotoxin and paralytic shellfish toxins derived from RNA of marine bacteria

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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