Cloned English' clone' comes from the Greek' KL! N' (twig) In horticulture, the word "clone" was used until the 20th century. Later, sometimes' e' is added to the end of the word to become' clone' to indicate that' o' is pronounced as a long vowel. Recently, with the widespread use of this concept and word in public life, spelling has been limited to the use of "cloning". In Chinese mainland, the Chinese translation of this word is "clone", while in Hong Kong and Taiwan, it is usually translated as "clone" or "copy". The former "clone" is like the transliteration "copy" of copy, which has the disadvantage of not looking at the literal meaning; The latter's "copy" can roughly express the meaning of cloning, but it is not accurate and easy to be misunderstood.
Cloning is usually artificially induced asexual reproduction or natural asexual reproduction (such as plants). Cloning is a multicellular organism, genetically identical to another organism. Clones can be natural clones, such as asexual reproduction or individuals with identical genes (just like identical twins). But what we usually mean by cloning is an identical copy produced by conscious design.
In biology, cloning is usually used in two aspects: cloning a gene or cloning a species. Cloning a gene refers to obtaining a gene from one individual (for example, by PCR), then inserting it into another individual (usually by vector), and then studying or utilizing it. Cloning sometimes refers to successfully identifying a certain -{A|zh-cn: phenotype; Zh-tw: dominant gene. So when a biologist says that the gene of a disease has been cloned successfully, that is to say, the position and DNA sequence of this gene have been determined. Obtaining a copy of this gene can be considered as a by-product of identifying this gene.
Cloning an organism means creating a new object with exactly the same genetic information as the original organism. Under the background of modern biology, this usually includes somatic cell nuclear transfer. In somatic cell nuclear transfer, the nucleus of oocytes is removed and replaced by the nucleus taken from cloned organisms. Usually, oocytes and their transplanted nuclei should come from the same species. Because the nucleus contains almost all the genetic information of life, the host oocyte will develop into an organism genetically the same as the nuclear donor. Although mitochondrial DNA has not been transplanted here, it is still relatively rare, and its impact on organisms can usually be ignored.
In horticulture, cloning refers to the offspring of a single plant produced by vegetative propagation. Many plants obtain a large number of offspring from one plant by cloning this asexual reproduction.
Clone is a transliteration of English clone. Scientists call the process of artificial gene manipulating animal reproduction cloning, and this biotechnology is called cloning technology.
Cloning technology can play a role in saving rare and endangered animals, expanding and improving animal populations, providing enough experimental animals, promoting the research of transgenic animals, overcoming hereditary diseases, developing high-level new drugs and producing internal organs for human transplantation, but if it is applied to human reproduction, it will produce a huge ethical crisis.
What is cloning?
Cloning is a transliteration of the English word clone, which comes from the Greek word klone. Its original intention is to cultivate plants through asexual reproduction or vegetative reproduction, such as stem cutting and grafting.
Today's cloning refers to the asexual reproduction of organisms through somatic cells and the population of offspring individuals with exactly the same genotype formed through asexual reproduction. Cloning can also be understood as copying, copying, that is, producing the same copy from the prototype, and its appearance and genetic genes are exactly the same as the prototype.
What did China clone?
Frog: 1952, unsuccessful.
Carp: 1963, as early as 1963, China scientist Tong Dizhou successfully cloned a female carp by injecting the genetic material of a male carp into the egg of a female carp, which was 33 years earlier than Dolly's cloning. However, because the related papers were published in a China sci-tech journal and were not translated into English, they are not well-known internationally. (From: Public Broadcasting Company)
In ancient mythology, the Monkey King turned his hair into countless bizarre stories of the Monkey King, expressing the illusion that human beings copied themselves. 1938, German scientists first proposed the idea of mammalian cloning. 1996, after Dolly the sheep was born, cloning quickly became the focus of the world's attention, and people could not help but wonder: Will we follow the sheep? This kind of problem makes everyone feel uneasy. However, the opposition to cloning has not stopped the unremitting pursuit of scientists. With the successful cloning of primates, such as cattle, rats, pigs and even monkeys, which are closest to human biological characteristics, it has been believed that one day, scientists will use a human cell to replicate exactly the same person as the cell provider. Cloning human beings is no longer a dream in science fiction, but a reality that will surface. At present, three foreign organizations have officially announced that they will conduct human cloning experiments. Professor zavos of the University of Kentucky in the United States is working with an Italian expert named Antinori to plan to clone a human within two years.
Because human cloning may bring complicated consequences, most countries with advanced biotechnology have adopted an attitude of explicit prohibition or strict restriction. Clinton said: "It is dangerous to copy human beings through this technology and should be eliminated!" "Hong Guofan, member of Chinese People's Political Consultative Conference and director of the National Gene Research Center of the Chinese Academy of Sciences, also made it clear that he opposed the study of human cloning and advocated distinguishing cloning technology from human cloning.
Is human cloning really as terrible as the devil in Pandora's box?
In fact, the main reason why people can't accept human cloning experiments is the obstacle of traditional ethics. For thousands of years, human beings have been following the way of sexual reproduction, but human cloning is a product in the laboratory and a life created under human manipulation. Especially in the west, cloning "abandoning God to divide Adam and Eve" has been opposed by many religious organizations. Moreover, the relationship between clones is also contrary to the traditional ethical way of determining kinship by blood. All these make it impossible for clones to find a suitable place to live in traditional human ethics. However, as He Xiuxiu, an academician of the Chinese Academy of Sciences, said, "The ethical issues of human cloning should be faced squarely, but there is no reason to oppose scientific and technological progress." The development of human society itself tells us that it is a historical progress for science and technology to drive people to update their ideas, while it is rigid to bind the development of science and technology with old ideas. Historically, blood transfusion technology, organ transplantation, etc. , has brought great ethical controversy, in 1978 when the first test-tube baby was born, caused an uproar, but now, people have been able to treat all this correctly. This shows that the idea of constantly updating in the face of scientific and technological development has not brought disaster to mankind, on the contrary, it has benefited mankind. As far as cloning technology is concerned, "therapeutic cloning" will make a breakthrough in producing transplanted organs and overcoming diseases, and bring revolutionary changes to biotechnology and medical technology. For example, when your daughter needs a bone marrow transplant, no one can provide it for her; When you unfortunately lost a 5-year-old child, you can't get rid of the pain; When you want to raise your own children but can't have children ... maybe you can realize the great scientific value and practical significance of cloning. The research of therapeutic cloning and the experiment of complete human cloning complement and promote each other. The end point of therapeutic cloning is the emergence of complete human cloning. If used properly, they can and should bring good news to human society.
Science has always been a double-edged sword. However, whether a scientific and technological progress is really beneficial to human beings depends on how human beings treat and apply it, rather than choking on it just because it is temporarily unreasonable. Cloning technology may indeed be the same as atomic energy technology, which can not only benefit mankind, but also cause endless harm.
As for people's fear that once the cloning technology is mature, thousands of "Hitler" will be cloned by people with ulterior motives, or another celebrity will be cloned to confuse people, that is a misunderstanding of cloning. The cloned person is only a genetic feature, and the social attributes such as thinking and personality influenced by many factors in the acquired environment cannot be exactly the same, that is, no matter how the cloning technology develops, only the human body can be cloned, but not the human soul, and there is an age gap between the cloned person and the cloned person. Therefore, the so-called human cloning is not a complete copy of human beings, historical figures will not be resurrected, and real people do not have to worry about having another "self".
All cloned items and cloning time
Sheep: 1996, Dolly
Macaque: Tetra, female, June 5438 +2000 10.
Pigs: in March 2000, 5 Scottish PPL piglets; August, Xena, female
Cattle: 200 1 year, alpha and beta, male.
Cat: 200 1 ending, plagiarist (CC), female.
Mouse: In 2002.
Rabbit: It was independently realized in France and South Korea from March to April, 2003;
Mule: May 2003, Gem, Idaho, male; June, Utah pioneer, male
Deer: Dewey in 2003.
Ma: Prometea, female, 2003.
Dog: Snoopy, Experimental Team of Seoul National University, Korea, 2005.
Pigs: On August 8, 2005, the first pig cloned from donor cells in China.
Although great progress has been made in cloning research, the success rate of cloning is still quite low: before Dolly was born, researchers experienced 276 failed attempts; After 9000 attempts, 70 calves were born, and one third of them died at an early age. Prometea also made 328 attempts to be born successfully. For some species, such as cats and orangutans, there are no reports of successful cloning. The cloning experiment of dogs is also the result of hundreds of repeated experiments.
Dolly's age test after birth showed that she was old when she was born. At the age of six, she developed arthritis, which is common in old age. This aging is thought to be caused by the wear of telomeres. Telomeres are terminal chromosomes. With cell division, telomeres are constantly worn during replication, which is usually considered as the cause of aging. However, after successfully cloning cows, the researchers found that they were actually younger. The analysis of their telomeres shows that they not only return to the length at birth, but also are longer than the telomeres at birth. This means that they can live longer than ordinary cattle, but many of them die prematurely because of overgrowth. Researchers believe that related research can eventually be used to change human life span.
Human cloning violates human bioethics.
Should modern science and technology, especially modern life science and technology, respect ethical principles and listen to ethical voices? Some experts pointed out that the secret cloning of human beings by some scientific lunatics in the United States violates human bioethics, and there are great controversies and a series of legal problems that are difficult to solve.
Recently, many domestic media reprinted an amazing news reported by foreign media: a group of scientific lunatics manipulated by cult organizations are conducting a secret human cloning experiment in the depths of the desert in Nevada, USA. According to the same principle that British scientists created Dolly, the world's first cloned sheep, they extracted cells from an American baby girl who died in February this year and cloned them. It is said that "if all goes well, the world's first clone will be born at the end of next year."
After the news was disclosed, cloning technology and its ethical issues once again became a hot topic of discussion. If this news is true, how to treat this matter and how to correctly evaluate and think about this issue, the reporter visited the director of the Ethics, Law and Society Department of the Southern Research Center of the National Human Genome and researcher Shen Mingxian of the Institute of Philosophy of the Shanghai Academy of Social Sciences. Professor Shen said: Since Dolly sheep was successfully cloned by Roslin Institute in England in 1997, driven by fame and fortune, people abroad have been proposing and trying to engage in human cloning research. Although governments have banned it, reports related to human cloning have appeared in newspapers more than once in the past two years. However, it is really shocking that this time the speed is so fast and it is related to cult organizations.
It is understandable that parents who have lost their beloved daughter hope to revive their daughter through cloning technology. But if scientists use this to carry out experiments on human cloning, it is worth discussing. Professor Shen believes that even if cults are abandoned, this practice is not desirable. As far as "human cloning" is concerned, he will live in the shadow of "I am a replica of the dead". How will this affect his psychology?
According to the viewpoint of bioethics, science and technology should proceed from long-term interests and benefit all mankind. It must follow the four internationally recognized ethical principles of "doing good, not hurting, independence and justice". Dolly's sheep cloning has successfully experienced more than 200 failures, and there have been deformed or aborted sheep. However, human cloning is more complicated and will undoubtedly encounter more failures. If we create unhealthy, deformed or short-lived people, it will be a violation of human rights.
Professor Shen pointed out that at present, the scientific community divides cloning into therapeutic cloning and reproductive cloning. The former uses embryonic stem cells to clone human organs for medical research to solve the problem of insufficient donors for organ transplantation, which is supported by the international scientific and ethical circles, but there is a premise that the embryos used for therapeutic cloning cannot exceed the limit of pregnancy 14 days. As for reproductive cloning, that is, human cloning, on the whole, it violates the principles of bioethics, so the mainstream opinion of scientists is firmly opposed. UNESCO, the World Health Organization, the International Human Genome Ethics Committee and governments all expressed their opposition to reproductive cloning very clearly. Even if human cloning is really born, we still have to stick to this basic position.
From Wen Wei Po, June 5438+065438+1October 8, 2000.
What we call the advantages and disadvantages of biotechnology mainly refers to cloning, and its advantages and disadvantages are as follows.
Pro: 1) cloning technology can relieve women's pain of not being a mother.
2) The implementation of cloning experiment has promoted the development of genetics and opened up a prospect for "manufacturing" animal organs that can be transplanted into human body.
3) Cloning technology can also be used to detect fetal genetic defects. Cloned fertilized eggs are used to detect various genetic diseases, and cloned embryos have exactly the same genetic characteristics as fetuses developed in uterus.
4) Cloning technology can be used to treat nervous system injury. Adult nerve tissue has no regeneration ability, but stem cells can repair nervous system damage.
5) In in vitro fertilization, doctors often need to implant multiple fertilized eggs into the uterus in order to choose one of them to enter the pregnancy stage. But many women can only provide one egg for fertilization. This problem can be well solved by cloning. This egg cell can be cloned into multiple cells for fertilization, thus greatly improving the success rate of pregnancy.
Disadvantages: 1) Cloning will reduce genetic variation. Individuals produced by cloning have the same genetic genes and the same disease sensitivity, and a disease can destroy the entire population produced by cloning. It is conceivable that if all cattle in a country are the same cloned product, a slight virus may destroy the animal husbandry of the whole country.
2) The use of cloning technology will make people tend to breed the most valuable individuals in the existing population, instead of promoting the survival of the fittest of the whole population according to the laws of nature. In this sense, cloning technology interferes with the natural evolution process.
3) Cloning technology is an expensive technology, which requires a lot of money and the participation of biological professionals, with a high failure rate. Dolly is the only result of 277 experiments. Although more advanced technology has been developed, the success rate can only reach 2-3%.
4) Transgenic animals increase the risk of disease transmission. For example, if a cow producing medicinal milk is infected with a virus, the virus may infect patients through milk.
5) The application of cloning technology to human body will lead to the artificial control of the genetic traits of offspring. The core of the controversy caused by cloning technology is whether genetic manipulation of human embryos can be allowed in early development. This is unacceptable to many ethicists.
6) Cloning technology can also be used to create "Superman", or people who are physically strong but mentally retarded. Moreover, if cloning technology can be effectively used in humans, men will lose their genetic significance.
7) The impact of cloning technology on family relations will also be enormous. A child born from his father's DNA clone can be regarded as his father's twin brother, but the birth time has been delayed for decades. It's hard to imagine how a person will feel when he finds himself just a copy of another person.
The origin of cloning technology
Cloning is a transliteration of English clone, which is simply an artificially induced asexual reproduction method. But cloning is different from asexual reproduction. Asexual reproduction means that there is no combination of male and female germ cells, and only one kind of organism produces offspring. The common reproduction methods are spore reproduction, budding reproduction and fission reproduction. By layering, cutting or grafting the roots, stems and leaves of plants to produce new individuals, it is also called asexual reproduction. Sheep, monkeys, cows and other animals cannot reproduce asexually without manual operation. Scientists call artificial gene manipulation of animal and plant reproduction process cloning, and this biotechnology is called cloning technology.
The idea of cloning technology was first put forward by German embryologist in 1938. 1952, scientists first carried out cloning experiments with frogs, and then people continued to study cloning technology with various animals. Because of the little progress in this technology, the research work once entered a trough in the early 1980 s, and later some people cloned it successfully with mammalian embryonic cells. 1On July 5th, 1996, British scientist Dr Ian Wilmut cloned a live sheep from adult sheep somatic cells, which brought a major breakthrough in the research of cloning technology. It broke through the technical difficulty that only embryonic cells could be used for animal cloning in the past, and achieved the goal of animal cloning with somatic cells for the first time, realizing animal replication in a higher sense. The goal of studying cloning technology is to find a better way to change the genetic composition of domestic animals and cultivate animal groups that can provide consumers with better food or any chemicals they may need.
The basic process of cloning is to transplant the nucleus of a donor cell containing genetic material into an egg cell without nucleus, then fuse the two cells through micro-current stimulation, and then promote the new cells to divide and reproduce and develop into embryos. When the embryo develops to a certain extent (it takes about 6 days for Roslin Institute to clone sheep), it is implanted into the uterus of an animal to make the animal pregnant and give birth to an animal with the same gene as the donor. In this process, if the donor cells are genetically modified, the genes of the offspring of asexual animals will also change in the same way. The main difference between "Honu Lu Lu badminton technology" and Dolly sheep technology that successfully bred three generations of cloned mice is that the genetic material in the cloning process is directly injected into the egg cells by physical methods, rather than cultivated in the culture medium. In this process, chemical stimulation is used instead of electrical stimulation to control the egg cells again. 1On July 5th, 998, scientists from Ishikawa Animal Husbandry Center and Animal Husbandry Laboratory of Feng Jingen University announced that two calves cloned from adult animal somatic cells were born. The birth of these two cloned cows shows that the technology of cloning adult animals is repeatable.
Dolly's birth means that human beings can produce the same life in large quantities from one tissue cell of an animal just like copying tapes or files, which is undoubtedly a breakthrough in the field of genetic engineering research.
People cut off the branches of plants and insert them into the soil, which will soon germinate and grow new plants. These plants are plants with exactly the same genetic material composition. This is called cloning. Also, the tubers of plants such as potatoes are cut into many small pieces for reproduction, and the offspring produced are also "clones". These are all asexual reproduction of plants, or "cloning". This phenomenon is so common that almost everyone has seen it.
(Figure) Dolly the Cloned Sheep
There is also asexual reproduction in the animal kingdom, but it is more common in invertebrates, such as split reproduction of protozoa and budding reproduction of caudate animals. But for advanced animals, under natural conditions, they can only reproduce sexually, so scientists must go through a series of complicated operating procedures to make them reproduce asexually. In 1950s, scientists successfully cloned an amphibian, Xenopus laevis, which opened a new chapter in cell biology.
In the late 1980s, Britain and China successively used embryonic cells as donors to "clone" mammals. By the mid-1990s, China had cloned five kinds of mammals, including mice, rabbits, goats, cows and pigs.
19 Dragon produced Dolly, a lamb with the same genetic structure as the donor, which caused an uproar in the world. Dolly is special in that its life was born without the participation of sperm. The researchers first sucked genetic material from a sheep's egg cell and turned it into an empty shell, then took out breast cells from a 6-year-old ewe and injected genetic material into the empty shell of the egg cell. In this way, an egg cell containing new genetic material but not refined was obtained. This modified egg cell divides and proliferates to form an embryo, which is then implanted into the uterus of another ewe. With the smooth delivery of ewes, "Dolly" came into this world.
But why don't other cloned animals have such great influence in the world? This is because the genetic genes of other cloned animals come from embryos, and they are all nuclear transplants with embryonic cells, which cannot be strictly said to be "asexual reproduction". Another reason is that the embryonic cell itself is sexually propagated, and the genome in its nucleus is half from the father and half from the mother. Dolly's genome is all from a single parent, which is really asexual reproduction. Therefore, strictly speaking, "Dolly" is the first truly cloned mammal in the world. 1On February 23rd, 997, scientists from Roslin Institute, Scotland, announced that the successful use of goat somatic cell "cloning technology" by their research team was the result of scientific development, and it had a very broad application prospect. In horticulture and animal husbandry, cloning technology is an ideal means to cultivate varieties with stable genetic traits. Through cloning technology, high-quality fruit trees and improved livestock can be cultivated. In the medical field, the United States, Switzerland and other countries have been able to use "cloning" technology to cultivate human skin for skin grafting. This new achievement avoids the possible rejection of allogeneic transplantation and brings good news to patients. According to China Xinhua News Agency1April 4, 1997, Cao Yilin, an expert in plastic surgery in Shanghai Ninth Staff Hospital, successfully cloned human ears in mice for the first time in the world, bringing hope for the repair and reconstruction of missing organs. Cloning technology can also be used to breed many valuable genes, such as insulin for treating diabetes, growth hormone that is expected to make dwarfism patients grow taller again, and interferon that can resist many diseases and infections.
Cloning is a major technological breakthrough in the field of biological sciences, which reflects the progress of nuclear differentiation technology, cell culture and control technology. Originally, it was a transliteration of English clone, which means the offspring individual population with the same genotype formed by biological cell asexual reproduction, referred to as "asexual reproduction".
The word "cloning" was introduced into horticulture in 1903, and gradually applied to botany, zoology and medicine. Broadly speaking, "cloning" is actually something we often encounter in our daily life, but it is not called "cloning".
In spring, the 6-year-old ewe has exactly the same gene, which can be described as a copy of her mother. It is worth noting that cloning technology will not only bring great benefits to mankind, but also bring disasters and problems to mankind. However, we can't stop its development, because it may bring serious consequences. In the final analysis, its advantages outweigh its disadvantages, and it will be beneficial to the wide application of human beings.