Gene-edited pufferfish and sea bream hit menus in Japan

Editor/Mohamed Shihab

Kyoto, Japan-based Regional Fish Institute is now selling gene-edited pufferfish to the public – one of the first times a gene-edited seafood product was offered over-the-counter to Japanese consumers.

The company’s online store has been offering the product since it gained government approval in 2021. The sale of gene-edited fish is part of a wider trend in Japan toward the new technology.

Unlike the European Union, Japan has had a more positive view of the use of gene editing in food. In 2018, the European Court of Justice ruled that all organisms produced by biotechnology were to be considered GMOs, and to be regulated as such. Accordingly, they must go through rigorous safety testing at the E.U. level. The E.U. public has also taken a different stance to genetically modified foods, as the use of genetic modification in some organisms is effectively banned in many countries.  

Following Brexit, the U.K. government is now pushing a genetic technology and precision breeding bill through Parliament. It would allow the setting of more-stringent rules for gene-edited crops and organisms than for GMO. However, those rules may be complicated by Scotland, which appears ready to assert that its devolved government can set its own rules on food safety.

In contrast to Europe's more conservative approach,, Japan has been more welcoming of gene-editing technology. In 2021, Japan’s government approved three gene-edited foods for commercial sale: a tomato with increased GABA content and two fish with faster growth and higher yield than their conventional counterparts.

Japan is not just allowing gene-editing, it is also funding it. In a 27 June press release, Regional Fish Institute announced that it had – along with Kyoto University and Tokyo Marine University – been awarded a government subsidy of JPY 97.5 million (USD 705,000, EUR 690,000) for research as a “year-2022 growth-type small and medium enterprise R&D support project.” The company will use the money to develop gene-edited tilapia and vannamei shrimp.

Japan has followed the lead of the U.S.A. and Canada in approving the sale of gene-edited foods with limited safety review, in contrast to the procedure for transgenic foods. In the former, an existing gene is deleted, or its effect reduced, while in the latter, new genetic material is introduced from another species. Transgenic foods pose a risk of introducing allergens into food products, while gene-edited foods contain no new genes, but rather deletion or the targeted mutation of a gene. It is also considered that changes of this scale sometimes occur randomly within the range of typical natural mutations.

In 2019, an advisory panel to Japan’s Ministry of Health, Labor, and Welfare recommended allowing gene-edited foodstuffs to be sold to consumers without safety evaluations, opening up new opportunities for such developments.

The stance has opened up the market for gene-edited fish, such as the two that were approved for sale in 2021. The two fish are a red sea bream lacking a myostatin gene which suppresses muscle growth, and a tiger pufferfish with its genes that control appetite removed. Both of the new fish were gene-edited using CRISPR gene-editing technology.

The fish were developed through a collaboration of Kyoto-based Regional Fish Institute, Kyoto University, and Kinki University; and Japan Ministry of Health, Labor and Welfare and the Ministry of Agriculture, Forestry and Fisheries.

The genome-edited red sea bream has 20 to 60 percent more edible yield than a conventional fish of the species, while feed utilization efficiency was increased by about 14 percent. It was introduced to the press by the universities under the nickname of “Muscle Madai” (madai means red sea bream in Japanese), but is being sold by Regional Fish Online as “22nd Century Sea Bream.” A set of about 16 thin slices on a bed of dried kelp is sold for JPY 3,000 (USD 21.69, EUR 21.24).

The genome-edited tiger pufferfish grows faster and achieves a 90 percent increase in weight over the conventional puffer in the same farming period. This allows a shortening of the farming period from the conventional two years. Sliced pufferfish sets are sold through the website in a variety of sizes and prices.

While faster weight gain and increased yield have been the goals of most gene-edited fish so far, other traits, such as disease resistance, are also possible. Plus, although the ease of use of the CRISPR-Cas9 system has been the trigger for an explosion in gene-editing, it is not the only choice for gene-editing, nor always the best.

A 2019 study in Japan, “Targeted mutagenesis of the ryanodine receptor by Platinum TALENs causes slow swimming behaviour in Pacific bluefin tuna (Thunnus orientalis)” the Platinum TALENs method of gene-editing was used rather than CRISPR to induce mutations in Pacific bluefin tuna. The change reduced the “burst swimming” ability of the tuna.

As a result, when the bluefin were disturbed by touching them, they swam away slowly, rather than with a burst of speed. Farm-raised tuna with burst swimming edited out may be less likely to break their necks by swimming at high speed into the walls of tanks and net pens, a common cause of mortality.

The trait has not yet been commercialized, but Japan’s farmed bluefin sector gained stronger footing in 2021, giving those pursuing the technology strong incentive to push their progress.