Chinese biologists first got the healthy young monkeys, which appeared due to the method of transfer of nuclei from somatic cells deprived of its own nucleus the egg. Born young Javanese macaques represent the complete genetic copies of the cells of the connective tissue of the monkey as a donor, from which was taken the nucleus for cloning. Recall that the first animal cloned in such a way, was the famous sheep Dolly, which came to light in 1996. The results of their work, Chinese geneticists describe in the journal Cell.
“A method of cloning monkeys gives us a lot of new possibilities. Now we can grow primates with exactly the same set of genes, with the exception of one stretch of DNA, whose structure we have changed. This will help not only to reveal the essence of many genetic diseases, but also to find new methods of dealing with cancer and disorders of the immune system,” says sun Qiang, Director of the Center for the study of primates at the Institute of neurophysiology KANG in Shanghai.
The first cloned animal on Earth, Dolly the sheep, was “the product of” three mothers, one of which left her their genetic material, and the second gave the first egg, and the third was carrying her after the successful transfer of DNA the first parent in a sexual cell of the second.
The birth of Dolly opened up a new era in biology and genetics – now scientists have the ability to create “clean” lines of experimental animals with exactly the same DNA and resurrect the extinct species. Initially, researchers feared that cloning technique leads to accelerated aging of the body and rarely succeeds, but in recent years they were able to show that it is not, and to increase the chances of success up to 70-80%.
According to the sun, despite all these advances, to date no research team was not able to clone a macaque or any other monkey in this way and Dolly.
“We tried to use several different methods of transfer of nuclei, and only one of them worked. We had to deal with a huge number of mistakes and failures before we found the right method of cloning monkeys,” continues the song.
The key to solving this problem, as noted by a Chinese biologist, was to accelerate the process of migrating the kernel from “normal” monkey cages of the donor to an empty egg cell, which significantly reduced the likelihood that the process of its further development will go down the wrong path. Additionally, the scientists developed a special “cocktail” of enzymes and RNA molecules that protected protein coat DNA from damage and forced the egg to share after entering the new kernel.
Primary culture of donor fibroblasts (A), the procedure of extracting the nucleus from an oocyte (B, C) and the procedure for the merger of the egg with the nucleus of a fibroblast (D-F)
The fruit of all efforts were two newborns Javanese macaques (Macaca fascicularis), produced by a surrogate mother of 8 and 6 months ago having exactly the same DNA. The first named Zhong Zhong, and the second is Hua Hua.
Zhong Zhong (left) and Hua Hua (right)
Like nicknames, as they note, are a kind of play on words – the expression of the Zhonghua means “Chinese people” in the language of China. Both monkeys have no health problems and grow and develop in the same way as all the other monkeys at this age.
According to Chinese researchers, a similar cloning technique succeeds in every third case the donor DNA are the connective tissue cells (fibroblasts), prepared in a special way. This figure, according to the sun, it will be possible to make even higher in the future through further optimization of the transfer procedure of the kernel.
Scientists admit that in the past science has been able to create a copy monkey, but in the strictest sense it was not a clone. Biologists have divided the embryo into several parts during the initial phases of its development, which led to the birth of not one, but two monkeys. In this way you can clone no more than four individuals at a time, which greatly limits the scientific usefulness of this technique in comparison with the ideas of Suna and his colleagues.
The scientists are cloning animals in the first place, in order to better understand the development processes of the embryo, however, such experiments have some practical use. For example, the cloning of monkeys would help to create models of genetically determined human diseases, which are necessary for studies of the mechanisms of development of these diseases and test drugs. Such models are applied in mice, but monkeys are genetically and physiologically much closer to humans, so these studies give more adequate results.
Fibroblasts of the fetus, which the Chinese scientists used for cloning, are easily subjected to genetic modifications, including using CRISPR/Cas9. Therefore, the successful cloning of monkeys from these cells means that the creation of genetically modified apes is not far off.
Opponents of the procedure of cloning argue that animals that appear on the light in such a way may contain hidden defects and therefore less viable. For example, Dolly the sheep differed in poor health, suffered from arthritis and lived only six years. However, recently scientists have found that no special predisposition to diseases of the Dolly was not, and it hurt, probably because of the content in indoor and low mobility.