The industrial application purpose of genetically modified muscled pigs is very clear
?? When you hear "pork belly," you will definitely think of pigs, but have you ever considered that one day pork belly might disappear from pigs? According to a June 30 report by the British Daily Mail, molecular biologist Jin Zhenxiu (transliterated) of Seoul National University in South Korea and his colleagues used the targeted gene knockout technique "TALEN" to remove the myostatin gene from pigs, then implanted these modified genes into pig embryonic cells, allowing sows to give birth to 32 piglets. The muscle cells of these piglets grow without restriction, turning them into "muscle pigs" rather than developing the chubby body shape of their companions. After 8 months, 13 piglets survived, and currently only 2 remain, of which only one has been assessed as "healthy." Jin Zhenxiu said that in the past, breeding a new animal variety took decades, but with the help of gene technology, it can be completed in a relatively short time. However, researchers have no plans yet to introduce "muscle pigs" into people's daily diets. Currently, many countries stipulate that because the environmental and human health impacts of genetically modified meat are unclear, the sale of such meat is not permitted.
According to another notice on the website of Yanbian University in Jilin Province, China, this achievement was completed through cooperation between the research group of Professor Yin Xijun of the university and the team of Jin-Soo Kim of Seoul National University in South Korea. The university's official website published a related report:
Recently, Nature/news reported on the research achievement of Professor Yin Xijun's team at Yanbian University, under the title "Super-muscly pigs created by small genetic tweak" (Nature 523, 13-14 02 July 2015 doi:10.1038/523013a). This innovative achievement was completed through cooperation between Professor Yin Xijun's research group at our university and the team of Jin-Soo Kim of Seoul National University. Nature is one of the most influential academic journals in the world. The papers it publishes represent substantive progress on an important scientific issue and have important near-term and long-term impact. This is the first time a scientific research achievement of our university has been reported in Nature News.
Nature reported that the Belgian Blue is the flagship breed of Belgian beef cattle and, after decades of breeding, has developed into a "bodybuilder cow" with the double-muscling gene, well-developed muscles, and a robust build. The research team used next-generation genome editing technology and somatic cell nuclear transfer technology, without relying on the introduction of exogenous DNA sequences, to simulate the natural mutation of the myostatin gene (Myostatin, MSTN) in large animals and obtain double-muscled boars, all of which exhibited characteristics of muscle overexpression. This type of double-muscled pig may become the first genetically modified animal approved for human consumption.
MSTN is a negative regulator of skeletal muscle growth and development, and loss of its activity manifests as the "double-muscle" trait in animals. In nature, MSTN gene mutations have been found in cattle, sheep, dogs, humans, and others. Among them, mutant cattle have already been bred into new beef cattle breeds and introduced by dozens of countries worldwide as terminal sires for crossbreeding improvement. The beef from these cattle is tender, low in fat and cholesterol, and high in protein, and is called "heart-healthy beef," making it highly favored by consumers in European and American countries. However, no pigs with MSTN gene mutations have yet been found in nature. To introduce the MSTN mutation, the research team used TALEN gene editing technology, constructing fusion proteins with nucleases to break the target gene DNA sequence at specific sites, thereby enabling DNA editing and modification operations at that site, such as knock-out, knock-in, base substitution, point mutation, or gene modification.
The research team designed and constructed a plasmid capable of efficiently knocking out the MSTN gene, transfected pig fetal fibroblasts by electroporation, sorted positive cells by magnetic bead sorting as donor cells, performed enucleation by a chemically assisted enucleation method, and then carried out somatic cell nuclear transfer; after embryo transfer confirmed pregnancy, fetuses were removed for gene sequencing, and fetal cells with bilateral MSTN gene knockout were used as donor cells for another round of somatic cell nuclear transfer, obtaining 32 double-muscled pigs (of which 13 survived to 8 months). In this study, the construction of the gene knockout plasmid and gene sequencing were undertaken by Pro. Kim's team, while Professor Yin Xijun's team at Yanbian University was responsible for gene transfection, somatic cell cloning, and the production and management of cloned animals.
Heiner Niemann, a senior researcher in the field of gene editing tools at the Friedrich Loeffler Institute in Germany, said that the pigs exhibited typical traits of double-muscled animals, which are typically characterized by well-developed muscles in the back and hindquarters.
Professor Yin Xijun explained that although the produced double-muscled pigs have a series of management problems common to other double-muscled animals, such as difficult births and low piglet survival rates, they can be used to establish a new concept of lean-meat breeds, increase lean meat percentage, meat quality, and economic benefits, achieving the goal of industrialization.
Next-generation gene editing should be regarded as a new technology developed on the basis of traditional mutation breeding, and in terms of safety it is more comparable to traditional mutation breeding technology - both are essentially equivalent to artificial mutation technology, and both merely accelerate the process of natural mutation. However, this new breeding technology is more precise and has a shorter cycle than traditional mutation breeding. Because this new technology can avoid relying on the introduction of exogenous DNA sequences, the genetically modified biological materials obtained through this technology are in fact not essentially different from the various natural polymorphic individuals formed through long-term evolution in nature. At present, the U.S. government approved the first plant material obtained through targeted genome modification in 2012, which can be directly evaluated in the field as a conventional variety.
Dr. Kang Jindan is the main researcher in charge of this project in Professor Yin Xijun's team and is one of the main contributors to this research achievement.
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