Paralytic toxins in a ribbon worm Cephalothrix species (Nemertean) adherent to cultured oysters in Hiroshima Bay, Hiroshima Prefecture, Japan

In 1998, during the surveillance of the toxicity of various marine fouling organisms in Hiroshima Bay, Hiroshima Prefecture, Japan, specimens of the r ibbon worm, "himomushi" Cephalothrix sp. (Nemertean) adherent to the shells of cultured oysters hanging onto floating culture rafts were found to cont ain toxins which showed strong paralytic action in mice throughout the surv ey period, February to May. The maximum toxicity (as tetrodotoxin, TTX) was 14,734 MU/g whole body. Attempts were made to identify the paralytic toxin s in this worm. The "himomushi" toxin (HMT) was extracted from the worm wit h 80 methanol acidified with acetic acid and the extract defatted with dich loromethane. The aqueous layer was chromatographed on activated charcoal an d the unbound and bound toxic fractions were analyzed by high-performance l iquid chromatography and gas chromatography-mass spectrometry. It was rathe r unexpectedly revealed from these results that HMT was comprised of TTX, 4 -epiTTX, anhydroTTX and three unidentified toxins. To our knowledge, this i s the first report of the occurrence of toxic organisms, containing a high concentration of TTX, adherent to cultured bivalves such as oysters. (C) 20 00 Elsevier Science Ltd. All rights reserved.