The cloned sheep "Dolly" born in 1996 made the public familiar with cloning technology for the first time. More than 20 years later, scientists have cloned many other mammals using somatic cell nuclear transfer technology: cloned cows and rats were born in 1997; Macaques with genes similar to humans were successfully cloned in 1999; Cloned pigs appeared in 2000; After that, cloning rabbits and horses was successful in 2003; In 2009, cloned camels were born in the UAE. In China alone, there are many varieties of cloned animals such as cattle, dogs, cats, and monkeys, and researchers have recently used it in the rapid breeding of high-quality dairy cows.
What is cloning?
The world's first cloned sheep "Dolly" was born in 1996. (Source: Reuters)
Cloning is transliterated from the English clone, which means asexual reproduction, that is, using the DNA of organisms (animals and plants) own germ cells or somatic cells to copy and reproduce, that is, a parthenogenesis method. Cloning in a broad sense we often encounter in our lives - after the cactus is cut into several pieces, each piece takes root when it lands on the ground; A strawberry plant can grow hundreds of strawberry seedlings in a year by relying on its creeping stems that "crawl" along the ground. This way of reproducing through a part of the organism itself is called asexual reproduction, that is, cloning in a broad sense.
However, most organisms today form a way in which sex cells (sperm and eggs) of both sexes exchange DNA with each other to reproduce, and the most important reason for this reproduction method is that exchanging genes adds or multiplies the excellent genes of both sexes, so that the offspring are healthier and stronger. As a result, cloning is today seen as an artificial, non-mainstream way of reproduction.
But the scientific significance of cloning has also been recognized by the 2012 Nobel Prize in Physiology or Medicine, awarded by John Gordon of the United Kingdom and Shinya Yamanaka of Japan, whose research has shown that mature, specialized cells can be reprogrammed to become all the tissues and life of the body. This means that even if animals or people cannot produce germ cells due to aging, and even the germ cells of the two sexes cannot blend, they can re-conceive life by obtaining specialized adult cells, such as intestinal cells, skin cells, etc., which is actually a reversal of life, because the DNA of qualitative, stereotyped mature cells still contains all the genetic information needed to develop into a life, and thus can re-conceive life.
The world's first cloned mammal, the "Dolly" sheep, was born in Scotland in 1996, which further proves the significance of cloning, and advanced life can reproduce without the need for germ cells of both sexes to exchange genes. Today, the meaning of "cloning" is not just "asexual reproduction", but an artificially induced asexual reproduction method. Biotechnology is used to produce offspring from asexual reproduction that have exactly the same genetic organization as the original individual, a process known as cloning.
China's leading achievement in cloned animals
The world's first somatic cloned monkey was born in China. (Source: Xinhuanet)
As early as 1981, scientists at the Institute of Hydrobiology of the Chinese Academy of Sciences cloned a fish from the kidney cells of adult crucian carp, proving that the somatic cells of adult fish can also be dedifferentiated and reprogrammed, which is 15 years earlier than the "Dolly" sheep cloned with adult somatic cells. Since there were no papers and public reports published internationally at that time, cloned fish were born silently and did not attract widespread attention.
Nowadays, China's cloning technology is at the advanced level in the world, although the cloning technology of the United States, Japan and South Korea developed early, but in recent years China has tackled cloning technology, there have been cloned cattle, cloned dogs, cloned cats and other breeds, and previously completed the first cloning experiment on non-human primates, few countries in the world have so many cloned species.
China's first somatic cloned cows were born in Ningxia
On January 31, 2023, the Ningxia Science and Technology Department officially announced that on the eve of the Spring Festival, three high-yield and long-lived cows copied by somatic cell cloning technology were born one after another in Lingwu City. This is the first time in China that somatic cell cloning technology is used to restore and preserve the germplasm of 100 tons of excellent individuals in the existing population, and it is used for efficient breeding of high-quality dairy cows, opening a new era in which somatic cloning technology plays a core and key role in the cultivation of high-quality dairy cows.
It is understood that the pregnancy rate of the first batch of 120 cloned embryos transplanted reached 42%, and the pregnancy rate of more than 200 days reached 17.5%. It marks the further maturity of this technology in practical application, and the first successful use of cloning technology in the key link of dairy cow breeding, reaching the international advanced level, which is another major breakthrough in the field of dairy cow breeding technology following the successful application of live egg collection-in vitro embryo production (OPU-IVP) technology in dairy cows in October 2022.
China's first batch of excellent somatic cloning cows was born in Ningxia. (Source: Northwest A&F University)
The world's first somatic cloned Arctic wolf was born in China
On June 10, 2022, a newborn cloned Arctic wolf with a dark body was born in Changping District, Beijing, weighing 520 grams and measuring 22 centimeters in length. It is known that the donor cells of the cloned Arctic wolf came from the skin sample of a wild Arctic she-wolf named "Maya" in Harbin Polar Park. Since then, the Chinese Academy of Agricultural Sciences has confirmed that this Arctic wolf cloned successfully with skin fibroblasts of Arctic wolves as donor cells is indeed the world's first case.
Arctic wolves are ice age survivors and are mainly found in the Arctic, including northern Canada and northern Greenland. Due to human harvesting of trees, environmental pollution and poaching, Arctic wolf populations and habitats are declining. In 2012, the Arctic wolf was added to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Experts believe that the birth of the world's first cloned Arctic wolf is a landmark event that is of great significance to the world's wildlife protection and the restoration of endangered species.
The world's first cloned Arctic wolf unveiled at Harbin Polar Park. (Source: People's Network)
The world's first somatic cloned monkey was born in China
On January 24, 2018, the Chinese Academy of Sciences held a press conference to announce that the mainland has realized somatic cell cloning of non-human primates for the first time in the world: on November 27, 2017, the world's first somatic cloned monkey "Zhongzhong" was born in the Institute of Neuroscience of the Chinese Academy of Sciences and the non-human primate platform of the Center for Excellence in Brain Science and Intelligent Technology; On December 5 of the same year, the second cloned monkey "Hua Hua" was born. Both cloned monkeys are female.
Cell, a top international academic journal in biology, published the results as a cover article and published it online on January 25, 2018. This achievement, independently completed by Chinese scientists, is known as "a milestone breakthrough in the field of life sciences in the world". This achievement marks that China has taken the lead in opening a new era of using somatic cloned monkeys as experimental animal models, and realized the transformation of mainland China from international "parallel" to "leading" in the field of non-human primate research.
The picture shows somatic cloned monkeys "Zhongzhong" and "Huahua". (Source: Xinhuanet)
The world's first gene-edited cloned dog was born in China
On July 5, 2017, Beijing Sinovalley Biotechnology Co., Ltd. announced that after the identification of the Nanchang Police Dog Base Dog DNA Laboratory of the Ministry of Public Security, the company's beagle dog "Longlong" and the world's first gene-edited disease model dog "Apple" have a probability of being identified as the same as 99.99%, and the parent-child relationship is excluded from the "surrogate dog", which proves that "Dragon Dragon" is a clone dog of "Apple". "Dragon Dragon" became the first somatic cell cloned dog completely independently bred in mainland China, and also the world's first gene-edited cloned dog.
"This marks that the mainland has become the second country after South Korea to independently master dog somatic cell cloning technology." Lai Liangxue, a researcher at the Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, said. According to reports, after the breakthrough of cloning dog technology, people can "customize" their functions according to their needs, such as breeding a batch of experimental dogs with the same genetic background and similar age at one time to study the mechanism of disease occurrence and verify the efficacy of new drugs; Knocking out or knocking in a gene in a dog makes the dog more sensitive and muscular, making it an excellent working dog such as a police dog or search and rescue dog.
Cloning opens up more possibilities
In fact, since the birth of the cloned sheep "Dolly", the ethical debate around cloning technology has never stopped. This breakthrough in scientific research affirmed the progress of human cloning technology, and at the same time caused controversy, including ethical and moral concerns about human cloning. Scientific research encourages free exploration, but it cannot be without the norms of scientific research ethics. In order to put an end to ignoring scientific ethics and morality, the mainland has also made special provisions at the institutional level.
It is understood that the mainland's scientific research ethics review system began in the 90s of last century. At that time, in order to adapt to the rapid development of biotechnology, the state increased the investment in projects such as the 863 Program, the 973 Program and the Natural Science Foundation, and established an ethical review committee according to the ethical evaluation requirements of international projects. Subsequently, the science and technology and health management departments began to attach importance to ethical review, and continued to increase the intensity of ethical review and supervision in scientific research and application. In this process, a series of ethical norms, norms and evaluation standards for scientific research have been formed, advocating scientific research activities that conform to ethical norms, and restricting or even prohibiting scientific research activities that do not conform to ethical norms.
At present, there are three main documents in the mainland's scientific research ethics, namely the Measures for the Ethical Review of Biomedical Research Involving Humans issued by the National Health and Family Planning Commission in October 2016, the Good Clinical Practice (GCP) for Drug Clinical Trials issued by the former State Food and Drug Administration in June 2003, and the Provisions on the Ethical Review of the Welfare of Laboratory Animals in Non-human Primate Experiments and Animal Experiments in International Cooperation Projects issued by the Chinese Center for Disease Control and Prevention in 2012 ( Trial)".
In addition, in June 1998, with the consent of the State Council, the General Office of the State Council forwarded and implemented the Interim Measures for the Management of Human Genetic Resources; In May 2001, the State Council also promulgated the Regulations on the Safety Management of Agricultural Genetically Modified Organisms; In December 2003, the Ministry of Science and Technology and the former Ministry of Health jointly issued the Ethical Guidelines for Human Embryonic Stem Cell Research, which clearly stipulates that research on reproductive cloning of human beings is prohibited and research on embryonic stem cells and therapeutic cloning is permitted, provided that norms are followed.
With the advancement of science and technology, gene and cloning technology is also constantly evolving. As a biotechnology with great application value, cloning technology plays an important role in the fields of basic life sciences, agricultural science research and production, and medicine.
In basic life sciences, genetic research on a variety of animals is realized through cloning technology, helping to clearly reveal gene function and the essence of life. In agriculture, attempts have been made to use gene transfer technology to create plants that are resistant to insects, diseases and drought. In the field of medicine, cloning technology plays a vital role in artificial organs and even xenotransplantation.
Looking to the future, if the scientific exploration and ethical issues raised by cloning technology can be solved and the cloning technology is used more rationally, cloning technology will win more positive attention in scientific development.
(Source: Xinhuanet, People's Daily, CCTV News, China Daily, Science and Technology Daily)