Novel proteinaceous toxins from the box jellyfish (sea wasp) Carybdea rastoni

During summer and autumn, the box jellyfish (sea wasp) Carybdea rastoni is one of the most bothersome stinging pests to swimmers and bathers on the Ja panese coast. Two labile but potent hemolytic toxins from the tentacles of Carybdea rastoni were isolated in their active forms using newly developed purification methods. The molecular masses of the isolated C. rastoni toxin -A and toxin-B (CrTX-A and CrTX-B) are 43 and 46 kDa, respectively, as calc ulated from SDS-PAGE. In the present study, we sequenced the full-length cD NA (1600 bp), which encodes both CrTX-A and CrTX-B. The deduced 450 amino a cid sequence of the CrTXs, showed no significant homology with any known pr otein. This report presents the first complete sequence of a proteinaceous jellyfish toxin. Furthermore, it was revealed that CrTX-A was primarily loc alized in the nematocyst, whereas CrTX-B was detected only in the tentacle. Because the nematocyst is the organ responsible for the cnidarian sting, t he remain der of the study focused on the toxicity of CrTX-A We found that CrTX-A was fatally toxic to mice at 20 mu g/kg (i.v.) and crayfish at 5 mu g/kg (i.p.). Subcutaneously injected CrTX-A (0.1 mu g) caused inflammation of mouse skin. These results showed that CrTX-A is responsible for the cuta neous inflammation observed in humans stung by C. rastoni. (C) 2000 Academi c Press.