Responsible Seafood Advocate
By Bonnie Waycott
With tools like CRISPR, can genome editing deliver more resilience for aquaculture?
In 2021, a new variety of red sea bream hit markets in Japan, the result of a trial by the Regional Fish Institute in Kyoto. It was the continuation of research published in 2018, when scientists at Kyoto and Kindai Universities manipulated fertilized fish eggs to knock out the myostatin gene that restricts muscle growth. With a meat content of around 1.2 to 1.6 times that of conventional sea bream, the new line of fish could be a huge boost for farmers, who would be able to grow meatier animals using less feed.
Japan’s work involves a genome-editing technology called Clustered Regularly Interspaced Short Palindromic Repeats, or CRISPR, which modifies genes by snipping out or adding in new segments of DNA. In aquaculture, CRISPR is being used to produce lines of fish boasting targeted traits such as disease resistance and fast growth.
“CRISPR is part of an immune-defence mechanism that bacteria use to defend against viruses,” Professor Ximing Guo at Rutgers University in New Brunswick, N.J., told the Advocate. “The bacteria contain enzymes, such as Cas-9, that can cut DNA at specific positions. For genome editing, a guide-RNA is also required to guide the Cas-9 enzyme so it can cut the DNA in the region you want and create a mutation that would either knock out a particular gene or replace that gene with a new, more effective copy.”
Guo breeds oysters for resistance against the diseases MSX and Dermo, which have devastated oyster fisheries along the U.S. Atlantic coast and in Maritime Canada. Going forward, he and his team are interested in using CRISPR to study gene function and possibly knock out the myostatin gene in scallops to produce bigger, meatier adductor muscles.
Guo says that Japan’s work is a solid example of how CRISPR can transform the genetic improvement of aquaculture species.
“It’s a very effective way of producing fish with more edible flesh while feeding them the conventional amount of feed, and it could potentially help to lower production costs or make production more effective,” he said. “It may be important to test the fish, however, to ensure that there is no significant impact on nutrient content and meat quality and demonstrate this to the public. If you are producing a type of fish that is more muscular, what would be the effect on nutrient content and how would that impact consumers? This needs to be made clear.”
BROWSE RELATED ARTICLES: