Are the traits of genetically modified fish safe?

Scientists from the fish transgenic engineering group of the Institute of Hydrobiology, Chinese Academy of Sciences, under the leadership of Academician Zhu Zuoyan, injected the growth hormone gene of grass carp into the fertilized eggs of carp, and bred a transgenic carp F1 generation with grass carp growth hormone gene and another transgenic triploid carp "Jili" with grass carp growth hormone gene.

The transgenic carp F1 generation is a transgenic "whole fish" gene fish composed of growth hormone genes of Yellow River carp and grass carp. It can grow to 1200 grams in 150 days and up to 2000 grams; it can reach 5000 grams in two years. Its growth rate is more than 140% faster than that of ordinary carp.

Jili is a non-fertile Jili bred by combining transgenic diploid carp with transgenic tetraploid fish (two sets of carp chromosomes and two sets of crucian carp chromosomes). Jili has the advantages of fast growth of grass carp and the taste of crucian carp. Since it cannot reproduce, there is no concern about hybridization with other fish and causing ecological crisis during the promotion process.

Are genetically modified fish safe?

The biosafety of genetically modified fish includes food safety, ecological and genetic safety. At present, the generally recognized safety evaluation principle of genetically modified foods is the "substantial equivalence" principle proposed by the Organization for Economic Cooperation and Development (OECD) in Europe in 1993, that is, whether genetically modified foods and food ingredients are substantially equivalent to traditional foods currently sold on the market.

The exogenous gene transplanted into the "whole fish" gene-transfected Yellow River carp is a grass carp growth hormone gene that is very similar to the endogenous growth hormone gene of carp. Transferring the grass carp growth hormone gene to carp is safe for carp; compared with traditionally farmed carp, the transgenic "whole fish" Yellow River carp carries the grass carp growth hormone gene and contains very small amounts of grass carp growth hormone. Like carp growth hormone, grass carp growth hormone is an extremely unstable polypeptide that already exists in the fish body. After physical treatments such as heating, it is decomposed into amino acids and loses its physiological function of hormones. It is as safe to eat as non-transgenic carp.

After the commercial breeding of transgenic "whole fish" fish, will it have an impact on fish germplasm resources and aquatic ecological environment? We might as well regard the "whole fish" gene transfer as a kind of "hybridization", that is, the hybridization of a gene with a species genome. The genome of fish has about 100,000 genes. The formation mechanism of the transgenic "whole fish" Yellow River carp can be simply compared to the hybridization of a grass carp gene and 100,000 carp genes. The degree of species heterozygosity is only one hundred thousandth of the hybridization of grass carp and carp. From this point of view, transgenic fish are much safer than any hybrid fish. Moreover, the reproductive capacity and adaptability of transgenic fish to the environment are not superior. Even if it is allowed to enter the nature, it is impossible for it to form a dominant population, inhibit the growth of other fish, and threaten the ecosystem. Moreover, the grass carp gene carried by the transgenic fish is only one of the 100,000 gene fragments of grass carp. Even if it can be hybridized with other fish, the possibility of causing genetic confusion is very small.

Artificially induced tetraploid carp and crucian carp

Researchers at the Institute of Hydrobiology, Chinese Academy of Sciences have recently cultivated a new excellent breeding variety - tetraploid carp and crucian carp. The mother of these tetraploid carp and crucian carp is an artificial compound triploid carp, which is a compound of 2 sets of carp and 1 set of crucian carp chromosomes; tetraploid is a compound of 1 set of crucian carp chromosomes superimposed on the 3 sets of chromosomes of the mother. The success of tetraploid carp and crucian carp breeding has opened up a new path for artificial directional breeding of fish in the future.

The success of tetraploid carp and crucian carp breeding is that researchers found that among the mature individuals of artificially induced compound triploid carp, the egg cells produced by a few individuals not only retained the original three sets of chromosomes, but also fused with a complete set of chromosomes of foreign sperm nuclei to produce artificial tetraploid carp and crucian carp. Since these tetraploid groups all come from the same mother, they have exactly the same genetics.

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