Distribution of Tetrodotoxin in Blue-Ringed Octopuses and the Hunt for Tetrodotoxin-Producing Symbiotic Bacteria

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The Malacologist




The Malacological Society of London

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Some blue-ringed octopuses (Hapalochlaena spp.) contain tetrodotoxin (TTX) in their posterior salivary glands and soft tissues (Sheumack et al. 1978). This potent neurotoxin inhibits action potentials in nerve and muscle tissue (e.g. Narahasi 2001). Because TTX occurs in several independently derived taxa besides newts and octopuses, such as puffer fish, clams, ribbon worms, and frogs (Miyazawa and Noguchi, 2001), involvement of symbiotic bacteria is hypothesized (Simidu et al. 1987, Yasumoto et al. 1989). Several strains of bacteria, including Vibrio spp., cultured from pufferfish (Noguchi et al. 1987) and the blue-ringed octopus (Hapalochlaena lunulata, Hwang et al. 1989) appeared to produce TTX. Hwang et al. (1989) cultured bacteria from the posterior salivary glands (PSG) of Hapalochlaena lunulata and found trace amounts of TTX in the colonies. However, Matsumura (1995) has called for a re-evaluation of the toxin identification in bacterial studies, because the medium on which the bacteria were cultured may cause a false identification of TTX when identified by high performance liquid chromatography (HPLC) or gas-chromatography coupled with mass-spectroscopy (GC-MS). Moreover, presence of synthetic byproducts of TTX in frogs (Daly, 1995) and lack of bacteria coincident with TTX-containing tissues in newts (Lehman et al. 2004) suggest a bacterial symbiont may not explain the origin of TTX in all cases. In the octopuses examined (Hwang et al. 1989), quantities of TTX were extremely low per bacterial culture and disagree with organismal levels of TTX. Chromatographic profiles of the purported toxin in this study were poorly resolved and near the limits of equipment detection. While bacterial production of TTX may have simply been inhibited outside the octopus host, re-examnination of TTX production and distribution in blue-ringed octopuses is warranted.


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