Chinese biologists for the first time received healthy young monkeys, which appeared due to the method of transferring the nucleus from the somatic cell to the nucleus devoid of its own nucleus. Born young Javanese macaques are complete genetic copies of cells of the connective tissue of the donor monkey, from which the cloning nuclei were taken. Recall that the first animal, cloned in this way, was the famous lamb Dolly, who was born in 1996. The results of their work are described by Chinese geneticists in the journal Cell.
"Creating a technique for cloning monkeys gives us a lot of new opportunities. Now we can grow primates with an absolutely identical set of genes, with the exception of one DNA site whose structure we changed. This will help not only to reveal the essence of many genetic diseases, but also to find new methods for fighting cancer and immune disorders, "says Qiang Song, director of the Center for Primate Studies at the Institute of Neurophysiology, CAS in Shanghai.
The first cloned animal on Earth, the Dolly lamb, was the "product" of three mothers, one of whom left her her genetic material, the second - gave the first egg, and the third - carried it after successfully transferring the DNA of the first parent to the sex cell of the second.
The birth of Dolly opened a new era in biology and genetics - now scientists have the opportunity to create "clean" lines of experimental animals with absolutely identical DNA, and also to resurrect already extinct species of living beings. Initially, scientists feared that the cloning procedure leads to an accelerated aging of the body and rarely succeeds, but in recent years they have managed to show that this is not the case and increase the chances of success to 70-80%.
As Sun notes, despite all these successes, so far no scientific team has been able to clone a macaque or any other monkey in the same way as Dolly.
"We tried to use several different kernel transfer techniques, and only one of them worked. We had to face a lot of mistakes and failures before we found the correct method for cloning monkeys, "continues Sung.
The key to solving this problem, as the Chinese biologist notes, was the acceleration of the process of nuclear transfer from the "ordinary" cell of the donor monkey to an empty egg, which markedly reduced the likelihood that the process of its further development would go along the wrong path. In addition, scientists developed a special "cocktail" of enzymes and RNA molecules that protected the protein envelope of DNA from damage and caused the egg to be divided after introducing a new nucleus into it.
The primary culture of donor fibroblasts (A), the procedure for extracting the nucleus from the ovum (B, C), and the procedure for the fusion of an egg cell with a fibroblast core (DF)
The fruit of all efforts was two newborn Javanese macaques (Macaca fascicularis), produced by the surrogate mother 8 and 6 months ago, having absolutely the same DNA. The first was named Zhong Zhong, and the second was Hua Hua.
Zhong Zhong (left) and Hua Hua (right)
Such nicknames, as the scientists note, are a kind of word game - the expression zhonghua means "Chinese people" in the language of the Celestial Empire. Both monkeys have no health problems and grow and develop the same way as the rest of the monkeys at this age.
According to Chinese researchers, this cloning procedure is completed successfully in every third case, if the DNA donor is the connective tissue cells (fibroblasts) prepared in a special way. This figure, according to Song, can be made even higher in the future in the course of further optimization of the nuclear transfer procedure.
Scientists admit that in the past science has already managed to create a copy of the monkey, but in the strictest sense it was not a clone. Biologists simply divided the embryo into several parts in the first phases of its development, which led to the birth of not one but two monkeys. Similarly, it is possible to "clone" no more than four individuals at a time, which greatly limits the scientific utility of this technique in comparison with the ideas of Sun and his colleagues.
Cloning animals scientists are primarily engaged in order to better understand the development of the embryo, but such experiments have some useful benefits. For example, cloning monkeys would help create models of genetically determined human diseases that are needed to study the mechanisms of developing these diseases and testing drugs. Such models are used in mice, however monkeys are genetically and physiologically much closer to humans, therefore such studies give more adequate results.
Fetal fibroblasts, which Chinese scientists used for cloning, are well suited to genetic modifications, including using the CRISPR / Cas9 system. Therefore, the successful cloning of macaques from these cells means that the creation of genetically modified monkeys is not far off.
Opponents of the cloning procedure argue that animals that appear in this way may contain hidden development defects and are therefore less viable. For example, Dolly the sheep was weak in health, suffered from arthritis, and lived only six years. However, recently the scientists found out that Dolly had no special predisposition to the diseases, and she was sick, most likely because of the content in an enclosed space and low mobility.
The article is based on materials .
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