05 July 2021

Hypoallergenic chick

The first cloned calf in Russia opened the way to genetically modified cattle

Natalia Safronova, "Scientific Russia"

Scientists from the L.K. Ernst Institute of Animal Husbandry, Skoltech, MSU and their colleagues received the first viable cloned calf in Russia – he has already turned one year and four months old. In parallel, the team managed to carry out a knockout of beta-lactoglobulin protein genes in the laboratory, which is responsible for milk allergy in humans. The experiment is a step towards obtaining genetically modified cows with hypoallergenic milk.

The study was published in the journal Doklady Biochemistry and Biophysics (Singina et al., Production of a Cloned Offspring and CRISPR/Cas9 Genome Editing of Embryonic Fibroblasts in Cattle).

A team led by Galina Singina from the L.K. Ernst Institute of Animal Husbandry cloned a calf using somatic cell nucleus transfer technology, using embryonic fibroblasts as nuclear donors. The technology involves replacing the nucleus of an egg with a nucleus from an ordinary cell of another individual. The result is an embryo that is transferred to the cow's uterus and is carried by her.

Although GMO mice have not yet become widespread in Russia, they have become commonplace in many countries. But editing the genome of other species, as noted by one of the authors of the study, associate professor of Skoltech Peter Sergiev, remains expensive and involves difficulties in breeding and breeding animals. Mice in this sense have a number of advantages, including a short, three-week pregnancy. In addition, laboratories around the world have been working with mice for decades, so a lot of experience has been accumulated in handling them.

"So the development of a methodology for obtaining cattle with hypoallergenic milk is not only a necessity from the point of view of agriculture of the future, but also simply a cool project," Sergiev comments on the study.

"A cloned heifer weighing 63 kg was born on April 10, 2020. Now, at the age of more than a year, it is already an adult individual weighing 410 kg with a regular reproductive cycle. The first year we kept her and her mother in a separate room, but since May she has been transferred to daily grazing along with the rest of the institute's cows. It took some adaptation, but it passed quickly," says Galina Singina.

Sergiev explains that cow cloning is the first phase of the experiment, the result of which should be the production of a genetically modified individual. So scientists made sure that the methodology was fine-tuned before implanting GMO embryos. With the help of CRISPR/Cas9 technology (Nobel Prize 2020), the team has already managed to "turn off" the PAEP and LOC100848610 genes, which are responsible for the production of beta-lactoglobulin in cows. The resulting line of genetically modified embryonic fibroblasts will be used as donors for somatic cell nucleus transfer during cloning.

Beta-lactoglobulin, the main allergen in cow's milk, is not an easy target, since two copies of two genes are responsible for it in the cow's genome at once. The team managed to deactivate three copies out of four, but, according to Sergiev, this is enough for further breeding of the "ideal" animal by traditional breeding.

In preparation for the next stage of the experiment, scientists are raising a herd of several dozen cows that will bear GMO calves. "Since there is no 100% guarantee in such a process, we have to roll the dice repeatedly, which is very expensive," Sergiev notes.

"I think this work will lay the methodological foundation for genetic engineering of livestock in Russia, after which more complex tasks will appear. For example, to make cows produce some proteins that they normally do not produce. This may have applications in biotechnology," the scientist concludes.

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