The pufferfish known as the Torafugu (Takifugu rubripes) has at least two claims to fame. First, the genome of this species was the first vertebrate genome to be sequenced and made publicly available after the human genome. Pufferfish genomes are the smallest known for vertebrates, only around 400 Mb, around an eighth the size of the human genome. Pufferfishes are appealing "model" vertebrates for genomic analysis in part because, although compact, their genomes have essentially the same genes and regulatory sequences as other vertebrates, so less effort is needed to obtain a comparable amount of information (Brenner et al. 1993). Analysis of the Torafugu genome together with those of another pufferfish,Tetraodon nigroviridis, and other vertebrates have provided new insights into the evolution of vertebrates (e.g., Jaillon et al. 2004). For technical information about the Torafugu genome, visit the Fugu Genome Project webpage.
Torafugus's second claim to fame is as a dangerous delicacy in Japan. Fugu is a Japanese dish prepared in various ways from certain species of pufferfish (Takifugu, Lagocephalus, Sphoeroides) or porcupinefish (Diodon)--but especialy from Ta. rubripes. What makes fugu so exciting and sets it apart from other fish sold in restaurants is that it is potentially deadly. Fugu can contain lethal amounts of the poison tetrodotoxin in the organs, especially the liver and ovaries, and also in the skin. The poison paralyzes the muscles while the victim remains fully conscious until eventually dying from asphyxiation. There is no known antidote. Even miniscule traces of the toxin are said to cause the diner’s lips to go numb and turn his mind to the possibility that this could be his last meal. With the stakes so high, chefs must be highly trained to prepare fugu and it is not widely available outside Japan—in fact, it is illegal to sell it in most or all of the European Union and its preparation and sale is tightly regulated in the United States.
Different pufferfish species and different body parts vary substantially in their level of danger (Noguchi and Arakawa 2008). Some recent research has indicated that the toxin may be derived from tetrodotoxin-laden bacteria working their way up the food chain to the pufferfish, making poison-free farmed fugu a possibility (e.g., see Yuan et al. 2011). Some purists, predictably, insist that the taste of farmed fugu cannot compare with the sublime flavor of the wild fish—or could it just be the lack of adrenaline in the diner’s body that tames the flavor of poison-free farmed fugu? Food writer Adam Platt's 2008 account of dining on fugu in Tokyo can be read in New York Magazine.
The genus Takifugu includes around two dozen species, all of which are found in marine waters around China, Korea, and Japan, although additional morphological and genetic analyses are needed to resolve some taxonomic questions (e.g., see Song et al 2001; Reza et al 2008). Yamanoue et al. (2008) used whole mitochondrial genome sequences from 15 Takifugu species and eight other tetraodontids (plus two outgroups.) Their analyses indicated that Takifugu species are very closely related to each other and speciated over a relatively short period in the limited area of the East Asian marine waters.
- Jaillon, O., J.M. Aury, F. Brunet et al. 2004. Genome duplication in the teleost fish Tetraodon nigroviridis reveals the early vertebrate proto-karyotype. Nature 431: 946–57.
- Brenner, S., G. Elgar, G., R. Sandford, A. Macrae, B. Venkatesh, and S. Aparicio. 1993. Characterization of the pufferfish (Fugu) genome as a compact model vertebrate genome. Nature 366: 265–268.
- Noguchi, T. and O. Arakawa. 2008. Tetrodotoxin – Distribution and Accumulation in Aquatic Organisms, and Cases of Human Intoxication. Marine Drugs 6: 220-242.
- Reza, M.S., S. Furukawa, T. Mochizuki, H. Matsumura, and S. Watabe. 2008. Genetic comparison between torafugu Takifugu rubripes and its closely related species karasuTakifugu chinensis. Fisheries Science 74: 743-754.
- Song, L., B. Liu, J. Xiang, and P.-Y. Quian. 2001. Molecular Phylogeny and Species Identification of Pufferfish of the Genus Takifugu
- Yamanoue,Y., M. Miya, K. Matsuura. et al. 2009. Explosive Speciation of Takifugu: Another Use of Fugu as a Model System for Evolutionary Biology. Molecular Biology and Evolution 26(3):623–629.