Bet on carp: gene editing of fish will help create a new aquaculture

Russian scientists have obtained carp specimens with an edited genome. Experts have disabled the myostatin gene in fish, which limits the increase in muscle mass. According to the calculations of geneticists, this will lead to a 20% increase in meat content. Scientists plan to get offspring from these carps and bring out a new product line in two generations. Currently, the use of organisms with an altered genome for agricultural purposes is prohibited in Russia. However, according to experts, the method of gene editing is fundamentally different from gene modification and the use of such products in food is absolutely safe. And the main obstacle to putting it into practice remains people's distrust of such technologies.

Carps with an edited genome

Specialists from the All-Russian Scientific Research Institute of Fisheries and Oceanography (VNIRO) obtained individuals of carps with an edited genome, in which the myostatin gene is disabled. It limits the growth of muscle mass in adult fish. As a result, scientists estimate that the muscle mass of carp will increase by 15-20%. The institute's staff received not just laboratory samples for research, but full-fledged organisms that will be used for further breeding of the new product line. It will take about a year and a half for the carp to reach the required size.

— We looked at the genome of these fish and saw the changes in it that we had planned. At the next stage, we need to get offspring from these individuals, all of whose cells will contain the edited genome. And only after that we will get carp, which can be bred and eaten. We will find fish with these mutations in their genitals, and they will become the parents of a new product line. It will take two generations," said Nikolai Muge, head of VNIRO's Department of Molecular Genetics.

In their work, the scientists used the CRISPR/Cas9 genomic editing technique, which is called genetic scissors. It allows you to make changes to the genome of higher organisms. The effect was on the mstn (myostatin) gene. This is a reverse regulator of muscle growth, which, when turned off, leads to a continued increase in muscle mass after reaching the optimal size of the fish.

— In this work, an editing complex for knocking out (disabling) the myostatin gene, consisting of a mixture of guide RNA and Cas9 endonuclease protein, was delivered to fish embryos by microinjection. As part of the methodology development, the sample consisted of 1011 experimental and 580 control fish, respectively. The presence of editing events was detected by sequencing methods," said Nikolai Muge.

The sample of the studied samples consisted of 115 experimental and eight control fish. Of the 115 samples, mstn gene editing events were detected in 12 fish (10.4%).

According to the developers, this will be the first commercial line of fish with an edited gene in our country, which will have improved economic properties. Currently, research is mainly conducted on cell cultures, less often on some aquarium fish species, such as, for example, zebrafish. Similar work is underway in Russia with goats and pigs, but real results are still far away. Attempts to create aquaculture with improved properties are being made all over the world. Experiments are underway, but the ultimate goal has not yet been achieved.

Prohibition of gene editing in agriculture

Currently, the practical use of plants, fish and animals with altered genes in agriculture in our country is prohibited. Although, for example, they are actively used in the USA and China. According to our legislation, gene editing is equivalent to gene modification. Although, in fact, these two approaches are fundamentally different. For modification, foreign DNA is introduced into the genome of an organism, and the CRISPR/Cas9 technique allows for small changes in genes that practically do not differ from natural mutations.

VNIRO scientists' research is funded by a grant from the Russian Ministry of Education and Science. Izvestia sent a request to the ministry about the possibility of allowing gene editing in agriculture, but had not received a response by the time the material was published.

— This intervention did nothing supernatural with the fish, it just turned off myostatin, which stopped muscle growth (at the optimum level). There are more muscles, and there is more meat in the fish. No new protein has been created, and nothing new has appeared in the fish at all. It's just that one gene was turned off. It's not even a GMO," said Mikhail Bolkov, a researcher at the Institute for the Study of Aging at the Russian State Scientific and Clinical Center of the Pirogov Russian National Research Medical University of the Russian Ministry of Health.

Genes are added to genetically modified organisms, for example, for resistance to diseases, cold, and pesticides. This allows the crop to survive and give more profit to farmers and livestock breeders. A new gene is being introduced into GMOs, but here they just edited their own. In this case, so that it is not readable and this molecule is not synthesized. It is completely safe for the one who eats this fish. This could possibly have consequences for the longevity of fish, but the task was to grow food, not a long-lived fish, the specialist explained.

As soon as a technology related to hormonal or genetic effects appears, prejudice immediately arises, says Mikhail Chebanov, director of Kubanbioresources. According to him, this is a global problem.

— For example, the lifetime production of salmon roe without slaughtering fish is very limited in the West. For this, natural hormones are used to make the caviar flow out by itself, but still it has not become widespread. At the same time, genetically modified products are widely used. And if the packaging contains true information about how and where this product was received, then there will be a buyer for it," the expert noted.

If special authorities conduct an examination and accreditation of genetically edited products, this will increase consumer confidence in them, the specialist emphasized.