How to clone an animal? How to clone a person? How to clone a plant? How was Dolly the sheep cloned? And what is a clone?

How to create a clone?

As is known, in the process of reproduction of most higher organisms, the daughter receives half of the genes from the father and half from the mother, that is, it differs in genotype (set of genes) from both the father and the mother.

In biology, clones are organisms that have the same genotype.

It should be remembered that it is almost impossible to obtain an absolutely exact copy when cloning - in the process individual development Some genes can “work” and some “be silent”; the activation of certain genes can be influenced by external factors.

How to clone an animal?

The first successful experiments in cloning animals were carried out in the mid-1970s by the English embryologist J. Gordon, when a new tadpole was obtained by transplanting the nucleus of a tadpole cell into a frog egg.

A significant contribution to solving the problem of cloning mammals was made by a Scottish group of researchers from the Roslyn Institute and PPL Therapeuticus, led by Ian Wilmut. In 1996, they published their publications on the successful birth of sheep Megan and Morgan as a result of the transfer of cell nuclei from sheep embryos into unfertilized sheep eggs. In 1997, Wilmut's group used the nucleus of an adult (rather than embryonic) cell and produced a sheep named Dolly.

In Dolly's case, the same nuclear transfer technology was used to clone animals from embryonic cells.

The transfer process uses two cells. The recipient cell is an unfertilized egg, the donor cell is taken from the animal being cloned. In the case of the sheep Megan and Morgan, the donor cells were taken from sheep embryos; in the case of Dolly, differentiated (adult) cells were used from the lower part of the udder of a sheep that was four months pregnant. The pregnant animal was chosen because the udder of a pregnant sheep is actively growing, that is, its cells are actively dividing and are characterized by increased viability.

Using a microscope and two very thin capillaries, DNA is removed from the recipient cell, then the donor cell, containing a nucleus with chromosomal DNA, is connected to the recipient egg cell, devoid of genetic material.

After this, some of the fused cells begin to divide and, once placed in the surrogate mother's uterus, develop into an embryo.

According to specialists from the Roslin Institute, only one out of thirty embryos implanted into surrogate mothers develops normally.

It was later discovered that the “normally developing” cloned sheep Dolly ages several times faster than her “normally born” relatives. According to one of the most likely explanations, aging occurs due to a programmed limitation on the number of divisions and lifespan of each cell of higher organisms. According to one version, this is determined by the length of the terminal sections of chromosome arms - telomeric repeats. With each cell division, their length decreases, which, accordingly, determines the remaining life time allowed for the cell. Since the cell of an already adult animal, which had previously undergone at least several divisions, was used as a donor cell when creating Dolly, the telomeres of her chromosomes were somewhat shortened by that time, which could determine the general biological age of the cloned organism.

How to clone a person?

Since the birth of the cloned sheep, there has been debate all over the world about the need to ban or allow human cloning.

It should be remembered that organisms with an identical genotype, that is, natural clones, are identical twins. Likewise, an artificially obtained “clone” of a person will be only the younger twin of the DNA donor. Just like twins, the clone and the DNA donor will have different prints fingers. The clone will not inherit any of the original individual's memories.

How to clone a plant?

Plant cloning, unlike animal cloning, is a common process faced by any gardener or gardener. When a plant is propagated by shoots, cuttings, or tendrils, this is an example of cloning. This is exactly how a new plant is obtained with a genotype identical to the shoot donor plant. This is possible due to the fact that as plants grow, cells do not lose the ability to implement all the genetic information contained in the nucleus.

based on materials from http://www.rusbiotech.ru/ and http://ru.wikipedia.org

Since the famous sheep Dolly, who was born without the participation of a male, was revealed to the world, interest in cloning has not waned even among people who are very far from biological science. And, of course, the most main question: “Is it possible to clone a person?” Moreover, every now and then a sensational headline will pop up somewhere: “British (American, Japanese, Chinese - insert as appropriate) scientists have successfully cloned a person!” True, these headlines do not appear in scientific almanacs or on the websites of research institutes and academies - but what kind of self-respecting layman reads serious scientific publications!

But seriously... it's theoretically possible. Why do we say "theoretically"? Yes, because there has not been a single experiment yet, and one can only talk theoretically. Scientists are in no hurry to begin practice, and there are reasons for this... and here we will briefly digress from objective reality and turn to science fiction.

In one of the episodes of the science fiction series Star trek: Next generation, the crew of the starship Enterprise encounters a mysterious planet where the descendants of the crew of another ship that once crashed live. The heroes are surprised that among the residents there are a lot of people who look the same, and soon these people put forward a strange demand: to hand over all the children who are on board the Enterprise.

It turns out that these people reproduced by cloning for many generations (after all, it was impossible to create a large population from a few surviving crew members naturally) - that’s why there are so many people similar to each other among them, and most importantly, the accumulation of genetic errors during the cloning process led to , that the last generation cannot be reproduced even in this way! That’s why they needed other people’s children...

Science fiction does not always live up to its epithet, but in this case the writers' idea turned out to be extremely close to reality. The same sheep Dolly was shown to the general public because this experiment was successful, but how many were unsuccessful? Hundreds! Intrauterine fetal death, death soon after birth, swelling, placental abnormalities, immune deficiency - this is only a small part of the list of violations that scientists encountered in animal cloning experiments. Animals were often born with serious heart defects and other vital defects. important organs, and this was due to those same genetic errors. Consequently, no one guarantees that when cloning a person, for every healthy person there will not be several hundred disabled people - much more than during natural reproduction. What to do with the result of a failed experiment? This is not a sheep that you can just pick up and kill - this is a person, his murder will be a criminal offense... or will it not be? Maybe a cloned person will not be considered a full-fledged individual with all civil rights? This humanity has already “passed through” in ancient times, without any cloning - and no one wants to return to this...

The question of human cloning can be posed somewhat differently: for what? The possibility of cloning great apes can be studied without any special ethical problems on the animal closest to humans - chimpanzees. Studying psychological differences in genetically identical people? This has been and continues to be studied remarkably well in twins. What practical value can human cloning have?

Those who judge cloning based on science fiction films like “The Sixth Day” usually imagine the matter this way: now we are cloning A.S. Pushkin - and he will immediately begin to write masterpieces for us. In reality, everything happens somewhat differently: the clone does not come out of the autoclave as an adult and “ready-to-eat” individual - it is an embryo that differs from the usual one only in that it is an exact genetic copy of the maternal one (precisely genetic - other factors that scientists also influence intrauterine development are called epigenetic, so the clone will not be an exact copy even in physical sense). Then this embryo is implanted into the uterus (and not put into a device - there are no such devices and are not expected in the foreseeable future), where it develops as an embryo of its species should develop, then it is born, grows, develops... and if it is a person, then he still has to be educated and trained. A clone of A.S. Pushkin, even if we create him, will not listen to Arina Rodionovna’s fairy tales, will not study at the Tsarskoe Selo Lyceum... and many things will not be in his childhood that made the “original” a great poet.

Perhaps the main argument against the cloning of geniuses is precisely that the people who will raise these children will initially consider their pupils to be geniuses... such an “experiment” is often carried out by some irresponsible parents, only they don’t grow up to be great writers or scientists and musicians, but ordinary hysterics and neurasthenics.

The idea of ​​“conveyor production” of ideal soldiers seems equally dubious - after all, such an “army of the future” will first require an “army” of surrogate mothers... and military power states in modern world is determined not so much by soldiers’ muscles as by the presence of high-tech weapons - and it makes much more sense to throw state resources at this “front” if we want to strengthen the army.

The hope that cloning will make a person immortal is completely meaningless: even if we managed to copy and download into the brain of a clone the entire life experience of the original (as the heroes of the film “The Sixth Day” do - in reality there is no such technology and is not expected), it would still the original could not have embodied himself in it and said: “Here, this is me—young again.” The maximum he can do is look at his clone and think: “This is how I was when I was young.” An egoist who is concerned about preserving “his beloved self” (and other people, as a rule, do not think about immortality) is clearly not satisfied with this option.

I can’t help but remember the statement of one citizen who hid behind his nickname and avatar in social network(it’s doubtful that he would say something like that to someone’s face): with the help of cloning, beautiful women can be replicated and distributed to men, and all other women should be destroyed... what can I say? This citizen definitely does not consider women as people. But this expresses the main problem of human cloning: in order to do this, we will have to stop considering a person to be a person.

So, the question about the possibility of human cloning can be answered this way: it is theoretically possible, but no one will do this, at least for lack of practical sense. The idea of ​​cloning individual organs and tissues for transplantation seems to be much more relevant (and not so acute from an ethical point of view) ... but its practical implementation is still far away.

Human cloning no longer seems as fantastic as it did some 20-30 years ago. In this issue we will talk about how much scientists have advanced in this matter and how soon we will be able to grow clones for ourselves.

Let's start, perhaps, with our smaller brothers, because it is animals that show the main successes in matters of cloning. Of course, we couldn’t ignore Dolly the sheep, who became the first cloned mammal back in 1995. And on January 24 of this year, scientists from China officially reported on the successful cloning of a monkey, which brought humanity much closer to creating its own copies. But such scientific experiments are primarily aimed at studying genetic diseases and new methods of combating cancer, which claims millions of lives every year.

Newborn clones often suffer from gigantism, liver, heart and brain defects, due to which the animals simply die. This is one of the main aspects preventing human cloning. Also, thanks to science fiction writers, people think about the absolute identity of a clone not only in appearance, but also, for example, in character. Unfortunately, this factor cannot be controlled, because Human consciousness is formed not only by genetics.

If we talk about complete cloning of human DNA, then such procedures are prohibited in most countries, which, however, does not interfere with the development of genetics. Scientists have managed to preserve human cord blood and grow stem cells from it. But they are the building material for growing new organs. On this moment humanity already has experience in transplanting not only skin and bones, but also artificially grown bladders and trachea.

It will be important to note that there is another method of cloning, which causes in society great amount disputes. This is the cultivation of a full-fledged human embryo consisting of about 100 cells. Its biomaterial is suitable for growing organs and other therapeutic purposes. True, such procedures are allowed only in the USA, India and the UK, as well as in some parts of Australia.

Finally, it is also worth noting that, despite the development of technology, we still live in a deeply religious society. The Pope and the Patriarch of the Russian Orthodox Church speak out against the idea of ​​a person trying on the role of God, and the lack of guarantees for the viability of the fetus makes one think about the ethics of cloning. All these factors, as well as various international conventions, are unlikely to allow legal human cloning in the next century, which, of course, will not prevent secret experiments, which are most likely carried out by transcontinental medical corporations.

Scientists from California managed to clone five human embryos, which were destroyed five days after the start of the experiment.

A group of scientists from California reported that they were able to clone five human embryos. Researchers conducted an experiment to create stem cells containing the genetic material of a certain person, RBC reports.

Scientists used the somatic cell nuclear transfer (SCNT) method, which was introduced in 1996. during the cloning of Dolly the sheep. The meaning of this method is to remove the nucleus of the donor's egg and introduce the nucleus containing DNA information. Skin cells from two men were used as a source of DNA.

The embryos were destroyed after five days for a detailed study of the resulting material. If the data is confirmed, this will be the first successful attempt to clone a person.

So far, scientists have not tried to extract miracle cells from freshly grown embryos, as this would lead to the destruction of the embryos. "In other experiments, scientists have cloned human embryos from embryonic cells from other embryos," says Leonard Sohn, a stem cell researcher at Harvard. - However, it has now become clear that people can be cloned more the easy way" The breakthrough is that we have grown an embryo using adult cells."

“We created five blastocysts from 25 donor eggs. This is a very high success rate,” says project manager Andrew French.

The scientists rejected accusations that their research was ethically unacceptable. "Because a large number of couples undergoing infertility treatment have expressed a desire to participate in the study, then we believe that the described method of obtaining a donor egg is appropriate and ethically acceptable,” say the researchers, who expect to use this technology to create biotransplants for patients suffering from a number of diseases.

Many scientists have welcomed research in this area. “This is the most apt description of cloning techniques using human material. However, we are still a long way from achieving the goal of obtaining embryonic stem cells,” says Robin Lovell-Budge from the Center for Stem Cell Biology at the British Medical Research Council. “I hope that the authors will have the opportunity to continue their research and obtain a chain of stem cells,” said Ian Wilmut, Dolly the sheep’s “father.”

However, the issue of human cloning has long been controversial in society. US President George W. Bush opposed the use of human embryos to obtain stem cells and rejected a bill designed to expand federal funding for such projects. The Vatican also condemned research in this area.

Nowadays, most countries in the world prohibit reproductive cloning of people. However, last year British scientists managed to obtain permission from the authorities not only for therapeutic cloning(embryos are grown to obtain stem cells and destroyed after 14 days) human embryos, but also for experiments on genetic crossing of animals and people at the embryonic level, the Segodnya newspaper reports. Activity genetic scientists will be controlled by special supervisory boards that will monitor the purity of the experiments.

The initiative of American scientists is not the first attempt to create a human clone. In 2004, Greek doctor Panagiotis Zavos announced that he had succeeded in cloning human embryos by growing cells taken from dead people, in an empty cow egg. He experimented with genetic material taken from three donors - a one-and-a-half-year-old baby who died after surgery, an eleven-year-old girl who died in a car accident, and a 33-year-old man who was hit by a car. Zavos claimed that he allowed the cells to multiply only for a short time and stopped the process as soon as their number reached 64. In Australia there is a whole sect of “clone worshipers” - the Raelites. The sectarians organized the Clonaid company, which, according to them, dealt with cloning of people. Clonaid has grown about 30 clones. However, the sectarians were unable to confirm the cloned origin of the newborns.