The birth of the first genetically engineered and cloned puppies

[VIDÉO] You may also like this partner content (after advertisement)

Since the emergence of the gene editing technique CRISPR-Cas9, more daring genetic manipulations are emerging. In particular, scientists have begun to apply the above technique to dogs. By combining gene editing with somatic cloning by nuclear transfer, Korean researchers have for the first time produced eagles with more stable and more evenly edited genes from the first generation. . This technique could eventually limit or even eliminate genetic diseases in purebred dogs, or allow the development of more targeted and precise treatments. But the limits of this approach are still poorly known and can pose ethical problems for animal rights defenders.

Nearly 36,000 years ago, humans began to domesticate wolves.Canis lupus), which would have since dropped to most dog breeds today (with some exceptions), including companion dogs (Canis lupus Familris). The wolf’s millennia of domestication, therefore, its genome has gradually modified its genome, to gradually adapt to human needs and preferences. This evolution would have taken place through natural selection, or through human migration – domesticated breeds may have crossed and mixed across continents.

Today, humans seem to want to influence this genetic evolution more radically thanks to biotechnology. Recently, researchers from the Korean company ToolGen combined CRISPR-Cas9 technology and cloning for the first time, and gave birth to two healthy cubs.

In dogs, the CRISPR-Cas9 technique was first used by Chinese researchers in 2015, on the same dog breed. The two dogs born from this experiment were oddly more muscular than average, especially thanks to the removal of the gene that expresses myostatin, which normally restricts muscle growth. The aim was clearly to develop a new breed more suitable for running and hunting.

This inexpensive, precise technology has inspired many other companies to experiment with new dog breeds or “revive” the pets of wealthy clients. The advantage of this technology is to remove the genes that cause disease, or even improve cognitive and physical abilities.

However, the basic technique is limited, as animals are born “chimeras”. With this technique, gene editing takes place directly at the level of a fertilized egg, which is then implanted in a pregnant woman. But because variation is not present in all cells, breeding is necessary to reproduce the genes with higher frequency in future generations.

Favorable traits resulting from gene editing can be passed on from generation to generation “, explained Liangxue Lai, a researcher at the key laboratory of regenerative biology of the Guangzhou Institute of Biomedical and Health, at the time, and one of the authors of the experiment on Hercules and Tiangou. ” It will be possible to breed a large number of genetically modified dogs, which can be marketed “, he added.

For somatic cloning by nuclear transfer, it was used in dogs, in Korea, to produce a black and white Afghan hound. Named Snuppy, the greyhound was born from the skin cells of one of the father’s ears, which were combined with the eggs of a surrogate female.

Advantages of the two techniques combined

In the new study, published in the journal Biotechnology BMC, Korean researchers have successfully combined this cloning technique with CRISPR-Cas9 gene editing. Thanks to this combination, no cross-breeding is required for the desired genes to be fully expressed.

The main advantage of this new method is its ability to eliminate pathological genetic mutations in purebred dogs. In fact, in practice, the lack of genetic diversity often leads to the more frequent occurrence of phenotypic recessive mutations. Thus, ToolGen’s technique can modify these genes without the risk of altering other traits and preserve the purity of the breed.

This technology can also contribute to the protection and conservation of biodiversity, by applying it to endangered species. Because of the existence of the species, these animals are often forced to breed among close relatives, whose numbers or territories are too limited. Inbreeding, which leads to more frequent occurrence of genetic pathologies, thus constitutes an additional threat to the survival of these species. Korean technology has the potential to alleviate this problem, by eliminating disease-causing mutations.

In their experiments, the researchers took skin cells that caused the DJ-1 gene mutation to block the expression of the protein it encodes. This gene is significantly associated with various diseases, such as Parkinson’s. Other genes have also been added, including one that expresses a green fluorescent protein to facilitate tracking of successfully transfected cells.

For nuclear transfer, cells are placed near the egg from which the DNA has been previously removed. The cells and eggs are then fused together by electrical impulses introduced into their environment. The 68 embryos obtained were implanted into six surrogate females.

However, from experience, we have only given birth to two puppies, who are now 22 months old and have not shown any abnormality. However, because diseases caused by DJ-1 are age-related, dogs can develop diseases with age.

The researchers also stress that these animals will only be used for medical research. Furthermore, this type of testing remains the subject of much ethical debate.

Source: BMC Biotechnology

Leave a Comment

Your email address will not be published.