Cloning (biology) is a natural occurrence or reception through multiple genetically identical organisms by asexual (including vegetative) reproduction. The term "cloning" in the same sense and is often used in relation to the cells of multicellular organisms. Cloning is also known as getting a number of identical copies of genetic molecules (molecular cloning). Finally, cloning is also commonly referred biotechnological techniques are used to obtain clones artificial organisms, cells or molecules. A group of genetically identical organisms or cells is a clone.
Cloning is widespread in nature in different organisms. In plants, natural cloning is done with different methods of vegetative propagation. In animals, cloning occurs when ameyoticheskom parthenogenesis and various forms of polyembryony. So, among vertebrates known clonally reproducing species of lizards, consisting only parthenogenetic females. In humans, natural clones - monozygotic twins. In some species of armadillo normally born from four to nine monozygotic twins. Widespread clonal reproduction of crustaceans and insects. Unique version of natural cloning recently discovered ants - small fire ant (Wasmannia auropunctata), males and females which are cloned independently so that the gene pools of the two sexes do not mix. In this species, working individuals develop from fertilized eggs, uterus - from unfertilized diploid eggs. In some eggs fertilized by males, all chromosomes mother destroyed and of these haploid eggs develop males.
The greatest attention of scientists and the public involves the cloning of multicellular organisms, which was made possible thanks to the success of genetic engineering. Creating special conditions and interfering with the structure of the cell nucleus, the experts make it develop into the desired tissue or even in the whole organism. Permitted in principle possible to reproduce even the dead body, while maintaining its genetic material.
A distinction is complete (reproductive) and partial cloning of organisms. When fully recreates the entire body as a whole, partial - the body is not completely recreated (for example, only certain of its tissue).
Reproductive cloning implies that the result is a body. Except for scientific purposes, it can be used to restore the extinct species or conservation of rare species.
One of the promising applications of cloning tissue - cell therapy in medicine. Such tissue derived from stem cells in the patient could compensate for the lack of their own and body tissue defects and rejected by the transplant. This so-called therapeutic cloning.
The Plant and Animal Cloning
Cloning of plants (more common usage the terms of tissue culture in vitro, clonal micropropagation of plants) is to regenerate whole plants from callus by varying the proportional relationship of cytokinin and auxin in the medium. For primary callus can be any plant cells and tissues (except repositories premortalnom state) because the plant cells are capable of dedifferentiation under certain phytohormones concentrations in the medium. But most often used for this purpose meristem cells because of their low degree of differentiation. In the medium for callus necessarily include auxin (for dedifferentiation of cells) and cytokinin (for the induction of cell division). after the callus callus can be divided and each part used for the regeneration of whole plants. Because the callus is a shapeless mass of undifferentiated cell, it is necessary to regenerate the plant morphogenesis induced by changes in the environment phytohormone concentrations. Cloning produces virus-free plants seedlings (using apical meristem as a source of cells) proliferate in large scale plants (including rare and endangered) Cloning of anthers and subsequent reduction provides a diploid homozygous for all genes of plants that can be used for further breeding. You can also cultivate on artificial media protoplasts of plants, of which in some cases can be regenerated whole plants (protoplasts suitable for transgenesis due to their lack of cell wall and the possibility of merging with other cells).
Cloning of mammalian possible by experimental manipulations eggs (oocytes) and animal somatic cell nuclei in vitro and in vivo. Cloning adult animals is achieved by transferring the nucleus of a differentiated cell into an unfertilized egg whose own nucleus removed (enucleated egg cell), followed by transfer of the reconstructed egg in the oviduct of the adoptive mother. But for a long time, all attempts to apply the method described above for the cloning of mammals have been unsuccessful. One of the first successful cloning of a mammal (house mouse), Soviet researchers have carried out in 1987, they used the method of electroporation for merging enucleated zygote cell mouse embryo with a nucleus.
A significant contribution to the solution of this problem was made by a group of researchers from the Scottish Roslin Institute and the company «PPL Therapeuticus» (Scotland) under the leadership of Ian Wilmut (Wilmut). In 1996, there were publishing them on the successful birth of lambs as a result of transplanting the nuclei of fibroblasts derived from fetal sheep, into enucleated oocytes. The final problem was solved by animal cloning group Wilmut in 1996, when born sheep named Dolly - the first mammal derived from adult somatic cell nucleus: a unique oocyte nucleus was replaced by the nucleus of a cell culture of mammary epithelial cells of adult lactating sheep. Further experiments were conducted successful cloning using various mammalian nuclei taken from adult somatic cells of animals (mouse, goat, pig, cow) and taken from dead frozen for several years, animal. The advent of cloning of animals has caused not only of great scientific interest, but also attracted the attention of big business in many countries. Similar works are in progress in Russia, but a focused research program does not exist. In general, animal cloning technology is still under development. The large number of thus obtained various organisms observed pathology, leading to death and fetal death shortly after birth, although the cloning of sheep in 2007 survived 5 minutes each embryo (in the case of Dolly - took 277).
In 2004, the Americans started the commercial cloning of cats, and in April 2008, South Korean customs officials have started training the seven puppies, cloned from somatic cells of the best investigative Korean dog breed the Canadian Labrador retriever. According to South Korean scientists, 90 % of cloned puppies will meet the requirements for operation in customs, while only less than 30% of normal puppies are tested for aptitude.
The Pros and the Cons of Cloning from Economic Point of View
- Stockbreeding and organs cloning
As was written by Meghani Zahra (2009), “the U.S. Food and Drug Administration (FDA) announced recently that food products derived from some animal clones and their offspring are safe for human consumption. In response to criticism that it had failed to engage with ethical, social, and economic concerns raised by livestock cloning, the FDA argued that addressing normative issues prior to issuing a final ruling on animal cloning is not part of its mission. In this article, the authors reject the FDA's claim that its mission to protect and advance public health can be accomplished without considering ethical issues or without making value judgments. The authors offer two arguments in support of their position. First, the agency's mission statement presupposes significant normative commitments and judgments. Second, the FDA's risk assessment of food products from cloned animals and their offspring is itself clearly shaped by a variety of normative commitments”
The event, which has been declared one of the greatest achievements of the twentieth century, was to clone the first mammal - a sheep named " Dolly." She was born July 5, 1999 in Edinburgh Roslin Institute. It is noteworthy scientific achievement has been an excellent example of the legacy of God genius of a man. It was not the creation of life and its media coverage was biased. This event and the subsequent successes in cloning various mammals are forcing us to put a number of questions about the validity and purpose of cloning animals and humans.
Technology by itself does not carry neither good nor evil. Technologies bring good or evil, depending on how they are used.
The birth of Dolly, named after the singer of songs in the style of Dolly Parton's country, at a cost of 277 failed attempts and 50 thousand dollars. As cloned Dolly ? Nucleus of the cell (somatic cell nucleus) adult sheep transplanted into another sheep egg from which previously removed own kernel, then this egg was placed in the uterus of a third sheep, became the " surrogate mother." The cell nucleus was obtained from an animal aged 4 to 6 years. Therefore, the question arose whether Dolly live as much as the usual live sheep, or her life will be shorter, because she was born already "adult" ?
As it turned out, Dolly grew old faster than usual. In 2002, she developed arthritis, and she died prematurely. Lulled her February 14, 2003, after the age of six she contracted lung cancer (sheep typically live for 11-12 years). During his short life, she gave birth to six lambs. In 2007, the method for transplanting the cell nucleus, applied for its "creation", was declared unfit for use when working with people.
Will the cloning benefit people by providing them with new drug substances or donor organs to be transplanted from animals to prolong human life? Will rich clone bodies for themselves ? At human cloning for the purpose of growing organs that then he would be able to transplant and thus secure his imaginary immortality need to kill the clone. This means that the purpose of human cloning advocates murder.
Such situations - real. People whose work involves issues of bioethics, understand this. Jeffrey Kahn, director of the Center for Bioethics at the Medical School of the University of Minnesota, said: " It's pretty shocking change in our ideas about biology."
In genetic cloning a mammal or human genetic information is copied only, defines the structure of the body (drawing) and some basic instructions for maintaining the life of this body. Identity of the cloned individual - not a copy, clone soul - not a copy (in the case of human or animal), as well as the spirit of a clone - not a copy (in the case of humans). Acquired knowledge, wisdom, memories, nature, behavior patterns, etc. are not transferred from the old to the new body. Learned behavior, personal development, professional interests and hobbies of the cloned individual will be different. Everyone will agree that even twins (a clone) - not twins. Outwardly, they may appear similar, but they have different fingerprints, retinal different and definitely a different personality.
Possible potential benefits that animal cloning could bring medicine can be very limited. But the reverse side of the coin promises us in serious trouble.
Cloning of farm animals is considered from the viewpoint of obtaining economic benefits from cloning. But what happens if we find an "ideal cow ", " pig ideal " or " perfect chicken ?" First of all, who will decide what is " ideal" ? " Ideal " can be considered an animal that per kilogram of feed consumed gives the most meat, milk, etc. Whatever the basis for decision-making, decisions are made on purely economic considerations.
According to Karin Verzijden, “cloning used for food production seems to be a mixed blessing. Althougt the technique may in future allow for the creation of elite livestock for meat and milk production, so far efficiency rates have been low and the health of a proportion of surrogate mothers and clones is compromised.”
If the percentage of successful results, it was high enough, this method would greatly facilitate the work of breeders. The clones have almost the same genetic material as the animal cell nuclei which were implanted into an egg with remote kernels. And no matter what sex it is an animal. In experiments with sheep can take a healthy animal cells, and thereby produce an animal with an exceptional quality of wool or meat in perfect quality. Speaking of cows, donor cells can be taken from animals other than the special milk or meat quality. Instead of breeding racehorses, which " dilutes " genes are genes Champions partner, you can get a clone of racehorses with particularly outstanding performance. Genetically, the offspring will be almost identical to the parent. Such offspring, no doubt, will win a lot of prizes.
- Human reproduction
If it is assumed that there would be enough careful research and experiments themselves are not prohibited by law, it is likely that one day people will be cloned. At present, it is impossible to predict with certainty whether the result is positive or not. What can be said about the potential benefits of such an experiment ? Human cloning would solve the problem of childless families, giving them children. If the ovaries are absent wife and the husband's sperm is not viable, you could take a core of tissue cells wife or husband of the tissue cells, and the use of donor devoid of nuclei egg of another woman. In the first case would have been my daughter, in the second - a son. Rebuilt, fully cycled gamete could be implanted into the uterus of the wife or the other woman, the surrogate mother, and develop it to term. The offspring would be virtually identical to the wife or husband. One can imagine a lot of options for such a situation.
According to L. Rudenko, “The Food and Drug Administration''s (FDA''s) Center for Veterinary Medicine issued a voluntary request to producers of livestock clones not to introduce food from clones or their progeny into commerce until the agency had assessed whether production of cattle, swine, sheep, or goats by somatic cell nuclear transfer (SCNT) posed any unique risks to the animal(s) involved in the process, humans, or other animals by consuming food from those animals, compared with any other assisted reproductive technology (ART) currently in use.”
What happens if we focus our efforts on growing only those "most desirable " animals ? We'll let the other less numerous and less productive breeds of animals disappear. They are not " desirable." But then if some mutant bacterium or virus can kill all of our " ideal" animal faster than we will find the antidote, where we take the genetic information to start all over again ? On the basis of the many compelling economic and scientific reasons, genetic information, which in itself are less numerous species, it is important to keep.
There is another problem - the genetic attenuation. If we are going to clone the "ideal " of animals, and then clone clones that sooner or later ? In genetics, the existing information is copied and passed to the next generation in new combinations. But the new information is not disclosed ever. This process enables the refreshment of the genetic information by conventional mixing and matching the crossing. However, when we clone clone refresh this mechanism is not involved. Again and again, copying the information, in the end some of it we lose. If we continue to clone clones will eventually be lost such an essential part of the information, with the result that the clones will become sterile. The problem of genetic attenuation rises before us clearly.
At the moment an obstacle to human cloning can be considered:
1. Technological difficulties, due to the fact that now neotrabotannosti cloning technology, this occurs due to a large number of failed attempts. Besides, there is one important limitation for cloning, namely, not a repeat of consciousness ;
2. Social and ethical dimension, ie due to the fact that technology as mentioned above, is unproven, there is a strong possibility of a large number of defective clones - the emergence of individuals with genetic mutations, etc. And this in turn is a threat to the human species ;
3. Ethical and religious dimension. Most religions human cloning are negative. This is due to the fact that man is the " creation of God," a man can not put yourself in the place of God and create clones itself, for it is pride, and it is known to be punishable. Legend of the Tower of Babel described in the Bible is a striking example of this was the punishment then the confusion of tongues ;
4. In terms of biosecurity form, this issue is also quite controversial. Possible mutations that can occur because of the novelty of the technology of cloning ;
5. Public opinion. In the report we have already cited the results of opinion polls, which show that the company was not opposed to therapeutic cloning (despite the fact that there exist ethical problems caused by the fact as to whether the embryo is the beginning of human life, the formation of his personality or not), but sharply against the reproductive cloning ;
6. The last and most important obstacle is the legal bans.
The human cloning also carries many cons within. As Susan Rhind writes, “Our experience with mammals shows us that any attempts at cloning humans are inherently unsafe at present. On these grounds alone, scientists should not condone human reproductive cloning, even without taking into account the equally important ethical and moral issues.”
Animal cloning can yield significant economic benefits. However, you should make every effort to preserve the original genetic diversity, leaving at least small natural populations of donors. On the other hand, human cloning, including all of the research that may lead to it, is totally unacceptable and should be prohibited by law. To date, 19 countries in Europe, Scandinavia and the Middle East, signed a treaty banning human cloning. It was announced that at the session of the U.S. Congress in January 1998, the proposal will be made immediately to prohibit human cloning. In response to the statement of one of the physiologist of the imminent start of the study in this direction, the Federal Office of Food and Drug Administration warned him that if his lab will do anything without the permission of the Office, it will be immediately closed. Everyone should understand that it is vitally important to not that in studies of the potential success has been achieved, and that they ultimately failed. As was written by James A. Riddle, “The primary concern for milk and meat from cloned animals is that inappropriate reprogramming may result in subde hazards that pose food consumption risks. As stated by the FDA, there is no a priori reason to expect that SCNT will introduce any new, potentially toxic substances into the milk or meat of otherwise healthy animals.”
Be considered attempts to correct certain genetic diseases, such as hemophilia, using genetic manipulation. These attempts were unsuccessful. In addition, the following issues are concerned about getting the human proteins in the milk of pigs, cows, sheep, and successful changes in the characteristics of plants by genetic manipulation. It must be remembered that this work with genes involves only the use of the material that God has given us, and that such studies are limited to rigid frameworks - genetic systems are too complex and manipulate them to avoid the unfortunate consequences is extremely difficult. We can fix the genetic system in which there is a flaw, but to improve a normal, healthy system genes, we simply can not.
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