How to clone an animal? How to clone a human? How to clone a plant? How was Dolly the Sheep cloned? And what is a clone?

How to create a clone?

As you know, in the process of reproduction of most higher organisms, the daughter individual 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.

Clones in biology are organisms that have the same genotype.

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

How to clone an animal?

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

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

In Dolly's case, the same nuclear transfer technology was used as when cloning animals from embryonic cells.

The transfer process uses two cages. The recipient cell is an unfertilized egg, the donor cell is taken from the cloned animal. In the case of Megan and Morgan sheep, 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, which contains a nucleus with chromosomal DNA, is connected to the recipient egg cell, which is deprived of genetic material.

After that, some of the fused cells begin to divide, and after being placed in the uterus of a surrogate mother, develop into an embryo.

According to the Roslin Institute experts, only one out of thirty embryos implanted in surrogate mothers develops normally.

Later it was discovered that the "normally developing" cloned sheep Dolly ages several times faster than its "normally born" relatives. According to one of the most likely explanations, aging occurs due to a programmed limitation in the number of divisions and lifespan of each cell in higher organisms. According to one version, this is determined by the length of the end sections of the 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 undergone at least several divisions before, was used as a donor when creating Dolly, the telomeres of its chromosomes were somewhat shortened by that time, which could determine the overall biological age of the cloned organism.

How to clone a human?

Ever since the cloned sheep was born, there has been an ongoing debate around 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. Similarly, an artificially obtained "clone" of a person will be only the younger twin of the DNA donor in time. Just like twins, a clone and a 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 that any florist or horticulturist has to deal with. When a plant is propagated by shoots, cuttings, tendrils, this is an example of cloning. This is how a new plant with a genotype identical to the shoot donor plant is obtained. 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 world was shown the famous Dolly sheep, born without the participation of a male, interest in cloning has not weakened 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 the right one) scientists have successfully cloned a person!" True, these headlines do not appear in scientific almanacs and not on the websites of research institutes and academies - but what a self-respecting layman reads serious scientific publications!

But seriously… it is theoretically possible. Why do we say "theoretically"? Yes, because so far there has not been a single experiment, only theoretically one can argue. Scientists are in no hurry to start practicing, 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 meets a mysterious planet where the descendants of the crew of another ship that once crashed live. The heroes are surprised that among the inhabitants there are a lot of people "of the same face", and soon these people put forward a strange demand: to give up all the children who are on board the Enterprise.

It turns out that for many generations these people reproduced by cloning (after all, it was impossible to create a large population of several surviving crew members in a natural way) - that's why there are so many similar people among them, and most importantly - the accumulation of genetic errors in 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 scriptwriters' 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 shortly after birth, edema, placental anomalies, immune deficiency - this is only a small part of the list of disorders that scientists have encountered in animal cloning experiments. Quite often, animals were born with serious defects of the heart and other vital important organs, and it was connected with those same genetic errors. Consequently, no one guarantees that when cloning a person, one healthy person will not have several hundred disabled people - much more than when reproducing naturally. What to do with the result of a failed experiment? It's not a sheep that you can just pick up and kill like that - it's a man, his murder will be a criminal offense ... or will it not? Maybe the cloned person will not be considered as a full-fledged individual with all civil rights? This humanity has already "passed" in ancient times, and without any cloning - and no one wants to return to this ...

The question of human cloning can be put in a slightly different way: for what? The possibility of cloning higher primates can be studied without any particular ethical problems in the animal closest to humans - the chimpanzee. Studying the psychological differences of genetically identical people? This has been remarkably studied and continues to be studied in twins. And what practical value can human cloning have?

Those who judge cloning based on science fiction films like The Sixth Day usually present it like this: now we are cloning A.S. Pushkin - and he will immediately begin to write masterpieces for us. In reality, everything happens a little differently: the clone does not get 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 mother (it is genetic - other factors that scientists influence on intrauterine development) are called epigenetic, so the clone will not be an exact copy even in physical sense). Then this embryo is implanted in the uterus (and not placed in an apparatus - there are no such devices and are not expected in the foreseeable future), where it develops as an embryo of its species is supposed to 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 it, will not listen to the fairy tales of Arina Rodionovna, will not study at the Tsarskoye Selo Lyceum ... and there will be many things in his childhood that made the “original” a great poet.

Perhaps the main argument against the cloning of geniuses lies precisely in the fact that people who will raise these children will initially consider their pupils to be brilliant ... such an “experiment” is often put by some irresponsible parents, only now they grow up not great writers, 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 the military power of the state in modern world is determined not so much by the muscles of a soldier, but by the presence of high-tech weapons - and it is much more reasonable to throw state resources to this "front" if we want to strengthen the army.

The hope that cloning will make a person immortal is completely meaningless: even if we were able to copy and upload into the clone’s brain the entire life experience of the original (as the heroes of the movie “The Sixth Day” do - in reality there is no such technology and is not expected), anyway the original could not be embodied in it and say: "Here, it's me - young again." The most he can do is to look at his clone and think: “This is how I was in my youth.” An egoist who is preoccupied with preserving his “beloved one” (and other people, as a rule, do not think about immortality) will obviously not be satisfied with this option.

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

So, the question of the possibility of human cloning can be answered as follows: it is theoretically possible, but no one will do this, even if there is no practical sense. Much more relevant (and not as acute from an ethical point of view) is the idea of ​​cloning individual organs and tissues for transplantation ... but its practical implementation is still far away.

Human cloning no longer seems such a fantasy as some 20-30 years ago. In this issue, we will talk about how 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 could not ignore Dolly the sheep, which 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 monkeys, which brought humanity much closer to creating their own copies. But such scientific experiments, first of all, are aimed at studying genetic diseases and new methods of fighting cancer, which claim millions of lives every year.

Newborn clones often suffer from gigantism, defects in the liver, heart and brain, due to which the animals simply die. This is one of the major obstacles to human cloning. Also, thanks to science fiction people, people think about the absolute identity of the 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 the complete cloning of human DNA, then such procedures are prohibited in most countries, which at the same time does not interfere with the development of genetics. Scientists have managed to save human umbilical cord blood and grow stem cells from it. But they are the building material for growing new organs. At the moment, humanity already has the experience of transplanting not only skin and bones, but also artificially grown bladders and trachea.

It will be important to note that there is another way of cloning that 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 only allowed in the US, 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 a person trying on the role of the Lord, 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 interfere with secret experiments that are most likely being 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 specific person, RBC reports.

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

The embryos were destroyed five days later for a detailed study of the material obtained. If the data is confirmed, then 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 will lead to the destruction of the embryos. "In other experiments, scientists have cloned a human fetus from the embryonic cells of other embryos," says Leonard Zohn, a stem cell researcher at Harvard. - However, it has now become clear that humans can be cloned more the easy way". The breakthrough is that we have grown the embryo using adult cells.”

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

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

Many scientists have welcomed research in this area. “This is the most successful description of the cloning technique using human material. However, we are still very far from achieving the goal of obtaining embryonic stem cells,” said 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 stem cell chain,” said Ian Wilmut, the “father” of Dolly the sheep.

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 increase federal funding for such projects. The Vatican has also condemned research in this area.

Now in most countries of the world 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) of 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, which will monitor the purity of the experiments.

The initiative of American scientists is far from the first attempt to create a human clone. In 2004, Greek doctor Panagiotis Zavos claimed 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 a surgical operation, 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, was engaged in cloning of people. "Clonaid" has grown about 30 clones. However, the sectarians could not confirm the cloned origin of the newborns.