Abstract
In 1998, during a toxicological surveillance of various marine fouling organisms in Hiroshima Bay, Japan, specimens of the ribbon worm, Cephalothrix simula (Nemertea: Palaeonemertea) were found. These ribbon worms contained toxins with extremely strong paralytic activity. The maximum toxicity in terms of tetrodotoxin (TTX) was 25,590 mouse units (MU) per gram for the whole worm throughout the monitoring period. The main toxic component was isolated and recrystallized from an acidified methanolic solution. The crystalline with a specific toxicity of 3520 MU/mg was obtained and identified as TTX by high performance liquid chromatography (HPLC)-fluorescent detection (FLD) (HPLC-FLD), electrospray ionization-mass spectrometry (ESI-MS), infrared (IR), nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC-MS). The highest toxicity of C. simula exceeded the human lethal dose per a single worm. A toxicological surveillance of C. simula from 1998 to 2005 indicated approximately 80% of the individuals were ranked as “strongly toxic” (≥1000 MU/g). Forty-eight percent of the specimens possessed toxicity scores of more than 2000 MU/g. Seasonal variations were observed in the lethal potency of C. simula. Specimens collected on January 13, 2000 to December 26, 2000 showed mean toxicities of 665–5300 MU/g (n = 10). These data prompted a toxicological surveillance of ribbon worms from other localities with different habitats in Japan, including Akkeshi Bay (Hokkaido) under stones on rocky intertidal beaches, as well as Otsuchi (Iwate) among calcareous tubes of serpulid polychaetes on rocky shores. Within twelve species of ribbon worms examined, only C. simula possessed extremely high toxicity. Therefore, C. simula appears to show generally high toxicity irrespective of their locality and habitat.
Highlights
Nemerteans are mostly marine, soft-bodied, vermiform invertebrates distributed worldwide, often inhabiting under rocks, among sessile organisms or within various sediments along coastal areas [1].With approximately 1200 known species [2], they comprise the phylum Nemertea, which is classified into three subgroups, Palaeonemertea, Pilidiophora (=Heteronemertea + Hubrechtella and related forms) and Hoplonemertea [3,4,5]
In 1998, during a toxicological surveillance of various marine fouling organisms in Hiroshima Bay, Japan, we found that palaeonemerteans in the genus Cephalothrix among sessile organisms on the shells of the cultured oysters, Crassostrea gigas, contained toxins with extremely strong paralytic activity [26]
The paralytic toxicity of a species of ribbon worms, found on the surface of the shells of cultured oysters hanging onto floating culture raft in Hiroshima Bay, was examined between 1998 and
Summary
Nemerteans are mostly marine, soft-bodied, vermiform invertebrates distributed worldwide, often inhabiting under rocks, among sessile organisms or within various sediments along coastal areas [1]. With approximately 1200 known species [2], they comprise the phylum Nemertea, which is classified into three subgroups, Palaeonemertea, Pilidiophora (=Heteronemertea + Hubrechtella and related forms) and Hoplonemertea [3,4,5] They are generally carnivorous, with no morphological or behavioral means of protection against potential predators. Bacq [13,14], who discovered two neurotoxins, each from (1) Amphiporus lactifloreus and Drepanophorus crassus and (2) Lineus longissimus and “Lineus lacteus” (=Ramphogordius lacteus) He suggested that these substances, which he called “amphiporine” and “némertine”, respectively, served in a defensive role, rather than being offensive venoms, such as those frequently associated with the prey captured by a characteristic eversible organ, the proboscis. We focus on the toxicity of TTX-containing species of ribbon worms in Hiroshima Bay and review the current information, compared with the toxicity of specimens from elsewhere
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