5 myths about cloning
Post-science debunks scientific myths and explains common misconceptions. We asked our experts to comment on the popular ideas of people about reproductive cloning.
A clone is an exact copy of the original
This is rather an inaccuracy
There are several ways to use the term "clone": as a designation of the offspring of a single cell (slang common in scientific circles) or as a designation of an organism that has an identical genome to the original (like Dolly the sheep, obtained by transferring the nucleus of the somatic cell of the "original" into the donor egg). The problem is that in both cases the genomes of the original and the clone will not be identical due to the accumulation of random mutations. For example, the cells of our body may differ from each other by a set of mutations acquired during division, although we must be a clone of the very first cell of the embryo. The same story with identical twins, who are actually clones of each other, but nevertheless differ in a set of mutations.
If this is not enough to believe in the non-identity of the clone and the original, you can switch from observing changes in DNA to epigenetic. At the level of epigenetic changes, all our cells are different, twin cells are even more different, and even a colony of cells (derivatives of the same cell) growing under the same conditions in a Petri dish will also contain cells slightly different from each other epigenetically. Thus, a clone is a perfect repetition of the original in a world where there are no replication errors and epigenetics, but in the real world it is only an attempt to recreate the original.
Maria Shutova, Candidate of Biological Sciences, Researcher at the Laboratory of Genetic Foundations of Cellular Technologies of the Institute of General Genetics of the Russian Academy of Sciences.
Cloning a mammoth is impossible
Theoretically it is possible
Theoretically, mammoth cloning is possible, and there is a non-zero probability that there will indeed be a cell in which mammoth DNA will be intact, therefore it can be used for cloning. There is also a non-zero probability that after some time scientists will be able to synthesize a full-fledged intact mammoth genome. That is, theoretically it is possible, but it is unlikely that such manipulations can occur in the near future with the help of cloning technologies, because in order to find a fossil mammoth cell that will contain a whole set of DNA, it is necessary to sort through and analyze about 10-14 cells. And it's hard for me to say how long it will take to artificially synthesize full-size DNA, but to date, about 106 nucleotides have been synthesized in Craig Venter's laboratory. And we will need to synthesize about 109 nucleotides, that is, in order to achieve such a technical level of synthesis, it will probably take at least another dozen or two years. Therefore, theoretically cloning a mammoth is possible, but it is unlikely that it will happen during the lifetime of the current generation.
Sergey Kiselyov, Doctor of Biological Sciences, Professor, Head of the Epigenetics Laboratory of the N.I. Vavilov Institute of General Genetics of the Russian Academy of Sciences
Cloned animals have no parents
It all depends on who we consider to be parents
Each person is the product of combining an equal number of genes of his parents, which are in the DNA of the father's sperm and the mother's egg. After fertilization, each gene (or rather, almost every one, because there are also genes of sex chromosomes and mitochondria) is present in two copies. Genes "work", or, as scientists say, are expressed, and as a result of the sequential switching on and off of certain genes, a full-fledged organism develops. In mammals, the egg is fertilized in the womb of the mother, where its development into a fetus takes place.
In cloned animals, everything happens a little differently. The very first and most famous clone was, of course, Dolly the sheep. She had neither father nor mother in the usual sense. In order for Dolly to be born, scientists took an unfertilized egg from one sheep and mechanically extracted a nucleus from it, which contained maternal genetic information. Further into such an enucleated one (nucleus is the "core") the egg was injected with a nucleus taken from the udder cell of another sheep. The result was an egg with a double set of genes – not because half of the genes belonged to the father and half to the mother, but because the udder cell of the sheep from which the nucleus was taken contained a double set of genes.
The last stage of the cloning process is identical to the gestation of fertilized eggs by a surrogate mother. The resulting egg with a double set of genes was planted in the womb of the third sheep, which bore the fetus – the future Dolly. As a result, Dolly may have a different number of parents depending on who you consider to be parents. From the point of view of genetics, Dolly is certainly a clone of the animal from whose udder cell the nucleus was taken. Therefore, her genetic mom and dad are the parents of this donor sheep. The surrogate mother is the lamb that bore Dolly. And she received the mitochondrial genes from the third animal – the sheep from which the egg was taken, she is Dolly's mitochondrial mother.
Konstantin Severinov, Doctor of Biological Sciences, Professor of the Skolkovo Institute of Science and Technology (SkolTech), Professor at Rutgers University (USA), Head of the Laboratory of Molecular, Environmental and Applied Microbiology of Peter the Great SPbPU
Human cloning is ethically unacceptable
Truth
The goals of reproductive cloning may be different. The first ethically unjustified goal is to recreate a complete genetic copy of an organism as a set of spare parts for a particular person, for example, in order to use the possibilities of transplantation as a way to combat aging, diseases, and loss of organ operability. If we grow a complete organism, considering it as a set of spare parts, we violate the key ethical dogma that one cannot treat a person as a means, but only as a goal. Any object that is alive, even if it is reproduced artificially, should be considered as a target. The situation with such cloning violates key ethical norms.
If we are talking about reproductive cloning not only for the sake of growing an organism, but for the sake of recreating the completeness of the biological and social, then this is impossible, because all genetic programs are implemented only in the environment. The main behavioral signs are quantitative, that is, their specific behavior depends not only on the norm of reaction inherent in the genotype, but also on the influence of society (intelligence, cognitive abilities, propensity for criminal behavior). Even if we repeat the norm of the genotype reaction, we will never create social conditions that allow us to achieve a similar manifestation of the trait. Society is very dynamic, and we cannot repeat its conditions that affected a particular person. In addition, it is necessary to take into account the selectivity of the reaction to individual factors. A person is influenced not only by purposefully created conditions, but also by factors of non-targeted influence: the environment, the media and other agents of socialization. Therefore, neither the target setting nor the mechanisms for implementing the idea of reproductive cloning are ethically and scientifically justified.
Elena Bryzgalina, PhD, Head of the Department of Philosophy of Education of the Faculty of Philosophy of Moscow State University, specialist in philosophical problems of biology and Medicine
Cloning will destroy genetic diversity
Not true
The birth of identical twins has not destroyed any genetic diversity on Earth so far. It is unlikely that cloning will occur on Earth with a higher frequency than the birth of identical twins. Man has existed not for two thousand years, but much longer, and during this time he was not destroyed, and twins were born. Therefore, even if we take another three thousand years, I doubt that humanity will be able to clone so many individuals.
Why? If we talk about a person, it is primarily because this is due to the fact that it is necessary to use female eggs for cloning, and in an amount much larger than nature uses for the normal process of childbirth. Therefore, in this case, we definitely will not be able to get closer to nature, even if we gather all the women of the Earth together. Cloning, of course, will not destroy genetic diversity, because the birth of identical twins throughout the history of mankind has not affected the genetic diversity of people in any way.
Sergey Kiselyov, Doctor of Biological Sciences, Professor, Head of the Epigenetics Laboratory of the N.I. Vavilov Institute of General Genetics of the Russian Academy of Sciences
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01.07.2016