| Research Abstract |
Members of the phylum Cnidaria (corals, sea anemones, jellyfishes) are equipped with nemaotocysts (stinging cells) which they use in capturing prey and for defense. Many cnidarians are considered hazardous sea-creatures due to the toxicity inflicted by their sting. The sting of some jellyfishes, such as Chironex fleckeri, Chropsalmus quadrigatus and Physalia Physalis have been reported to be lethal to humans. Cnidarian toxins have been extensively studied and chemically characterized as mostly proteinaceous. The exact chemical properties of cnidarian toxins have not been elucidated due to their labile nature, except for some moderately stable neurotoxic polypeptides from sea anemones. Recently, we have developed a novel purification method for isolating unstable proteinaceous toxins from jellyfish. This purification method has resulted in the isolation of active protein toxins from three species of box jellyfishes (sea wasps), Carybdea rastoni, Carybdea alota and Chropslmus quadrigatus. C. rastoni is one of the most annoying sea-creatures for swimmers and bathers in Japan. C. alata is a common stinger in Hawaii. The sting of these three Species has been documented to induce cutaneous pain and inflammation in humans. Lt has been reported that the sting of C. quadrigatus from Okinawan resulted in three fatalities. RT-PCR and 5'-/3'-RACE methods were used to elucidate the full-length nucleotide and amino acid sequences of the isolated proteinaceous toxins from C. rastoni, C alata and C. quadrigatus Comparison between the proteinaceous toxins (43-45 kDa) from the three jellyfishes demonstrated 22-44% homology. Since these toxins did not show any homology with any other known protein, it is suggested that these toxins represent a novel class of bioastie proteins.
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