Highly Toxic Ribbon Worm Cephalothrix simula Containing Tetrodotoxin in Hiroshima Bay, Hiroshima Prefecture, Japan

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.

Assessment of Neuronal Cell-Based Cytotoxicity of Neurotoxins from an Estuarine Nemertean in the Han River Estuary

“…The present study was conducted to evaluate the neurotoxicity of the estuarine heteronemertean Y. pratensis [19], collected from Korean waters, toward nerve cells. Although the toxicity of Nemertea found has been widely reported [2,15,16,[22][23][24], the neurotoxicity of this heteronemertean isolated from the Han River estuary has not been investigated, and it has not been subjected to taxonomic analysis. Therefore, in this study, neurotoxins were extracted from the ribbon worm in the estuary of the Han River.…”

“…Nemerteans, also called ribbon worms, live all over the world, mostly in marine benthic habitats, although some species have stayed to live in freshwater and land habitats. Nemerteans have no means of defense against potential predators but they rely on various toxic or noxious chemicals for their defense and predation [1][2][3]. They are basically carnivorous, feeding on small crustaceans, polychaetes, and mollusks [4][5][6], and usually range from several centimeters up to 50 cm in length.…”

“…It has been known that free-living nemerteans use their proboscis for prey capture by everting the proboscis for wrapping the prey's body tightly with explosive force [7,8]. In this process, it seems to use neurotoxins to kill them before eating [2].…”

Defensive symbioses of animals with prokaryotic and eukaryotic microorganisms

“…Recently, the nemertean ribbon worm Cephalothrix simula was found to contain high concentrations of TTX and several of its analogues. 168 Shortly aer, Magarlamov et al isolated TTX-producing Bacillus species from C. simula individuals and used immunohistochemical methods to tie TTX production to the bacteria and localize the compound in the maturing spores. 166 If substantiated and combined with more detailed analyses on the nature and consistency of the Bacillus-C. simula association, these results could provide the rst demonstration of symbiont-produced defensive TTX.…”

Toxins of Pufferfish—Distribution, Accumulation Mechanism, and Physiologic Functions

“…In 1998, a ribbon worm that accumulates an extremely high concentration of TTX was found in Hiroshima Bay, Hiroshima Prefecture, Japan, and later identified as "akahanahimomushi" Cephalothrix simula (Asakawa et al 2013). We investigated the intra-tissue microdistribution of TTX in this species by the immunohistochemcal technique (Tanu et al 2004).…”