Pufferfishes are harmless (if uneaten) and sometimes also seen on our shores. Belonging to Family Tetraodontidae, pufferfishes harbour tetraodotoxin, a potent toxin that may be concentrated in the intestines, reproductive organs or skin.
Where does the toxin come from?
From marine bacteria!
From Marine Bacteria Which Produce Tetrodotoxin Usio Simidu et al Applied and Evironmental Microbiology July 1987, p. 1714-1715 Vol. 53, No. 7 0099-2240/87/071714-02$02.00/0
The study suggests that tetrodotoxins found in animal organs are the products of marine bacteria. Tetrodotoxin producing bacterium have also been found in the intestines of a crab, Atergatis floridus. Another tetrodptoxin-producing bacterium has also been found in a calcareous red alga, Jania sp. Tetrodotoxin-producing bacteria have also been isolated from various marine organisms, including a starfish, Astropecten polyacanthus, a horseshoe crab, Carcinoscorpius rotundicauda, and the blue-ringed octopus, Octopus maculosus.Despite the notoriety of pufferfishes and their toxins, they have provided many useful insights and applications for human health.
Although the role of the toxin in animals is still not entirely clear, the fact that scared animals exude the toxin into surrounding seawater suggests that the toxin has a protective function. There are a few established cases where the toxin has a distinct function; e.g., the blue-ringed octopus, 0. maculosus, which lives in tropical and subtropical seas, stores the toxin in large, second salivary glands and injects it when it attacks other animals, thus poisoning them. The role of tetrodotoxin in the bacteria themselves is not yet clear.
from Pufferfish DNA Yields Clues To Human Biology ScienceDaily 31 Jul 02;
Researchers who completed the study of the genome of the Japanese pufferfish Fugu rubripes and through a comparison with the human genome, twere able to predict the existence of nearly 1,000 previously unidentified human genes. Pufferfish have the smallest known genomes among vertebrates, the group of animals with backbones that includes humans. The Fugu sequence contains roughly the same number of genes as the much larger human genome, but in a compact form streamlined by the relative scarcity of the "junk" DNA that fills much of the human sequence.Tetraodotoxin extracted from pufferfishes has also been applied as a fast acting, long lasting and non-addictive treatment for heroin and opioid withdrawal, and in pain relief in cancer. It works by blocking slow sodium channel nocicipetive pain fibres in a highly selective way.
More about the recent case of poisoning
Three still critical after eating blowfish testicles
AFP 29 Jan 09;
TOKYO (AFP) — Three Japanese diners remained in a critical condition on Wednesday after eating blowfish testicles, a dangerous delicacy prepared by an unlicensed chef, police said.
"The three men remain hospitalised. They are heavily poisoned and their consciousness has been impaired," said a police official in northern Yamagata prefecture.
A group of seven men reported feeling numb on Monday soon after eating the testes of "fugu" blowfish, which is highly prized in Japan but is supposed to be prepared only by specially trained chefs because of its potential risk.
Northern Japan is known for imposing less stringent rules on fugu than Japan's culinary hubs of Tokyo and Kyoto.
The diners ate raw meat and baked testes of blowfish at a restaurant in Tsuruoka, an old castle town by the Sea of Japan (East Sea), 350 kilometres (220 miles) north of Tokyo.
The restaurant's owner as in police custody. Media reports said he was a former fisherman who did not have a proper licence to prepare fugu.
The victims, some of whom were understood to be frequent visitors to the restaurant, were offered the fugu dishes by the owner as off-the-menu specials for the winter season.
Blowfish poison scare returns to Japan
AFP 28 Jan 09;
TOKYO (AFP) — Seven Japanese have fallen ill with one in a critical condition after eating the testes of blowfish, police said Tuesday, renewing public fears over the dangerous delicacy.
The group ate raw meat and baked testes of blowfish -- known in Japan as fugu -- at an upscale restaurant late Monday in Tsuruoka, an old castle town by the Sea of Japan (East Sea), 350 kilometres (220 miles) north of Tokyo.
They were treated at a hospital for numbness in the hands and legs and other symptoms. One of them was in a critical condition on Tuesday.
"The victims included many public welfare volunteers and a town head. They came to party at the restaurant after a public welfare meeting," a Tsuruoka police spokesman said.
The seven men were aged between 61 and 69, except for a 55-year-old secretary at a community centre.
The restaurant, "Kibunya," did not have a licence from the provincial administration to prepare and serve blowfish, which contains tetrodotoxin in its organs, a powerful neurotoxin that can cause death in minutes.
Kibunya's owner, Iwao Aizawa, was being questioned by police on suspicion of professional negligence resulting in injuries.
"It is not so common to eat fugu in this region as it is caught in seas farther south. The fish was purchased from an ordinary dealer," the police official said.
Fugu, cooked in a cauldron or eaten in raw slices, is appreciated in Japan as a culinary delight, especially in the cold winter months. Its testes, known as shirako, are praised as creamy and rich in taste.
Blowfish deaths have fallen since 1983 when the health ministry instructed local authorities to ban eating of its dangerous parts. Only licensed chefs are now allowed to serve blowfish.
Six people died of blowfish poisoning in 2002 but since then Japan has seen no more than three deaths a year, according to health ministry statistics.
Blowfish is even called "teppou (gun)" in western Japan for its famous danger. In 1975, renowned kabuki actor Mitsugoro Bando VIII died at the age of 69 from eating a blowfish liver at a restaurant in Kyoto.