The first case of cloned piglet in China was revealed

After more than a year of scientific and technological research, the research group led by Professor Li Ning of China Agricultural University finally got a return on August 5, 2006. In Minghui@#@227@#@Company, Sanhe City, Hebei Province, China's first cloned pig was successfully born, which filled the gap in this field in China.

China is the seventh country to obtain somatic cloned offspring of pigs

At 10:50 a.m. on August 5, a cloned piglet weighing 1130 grams with black and shiny fur was successfully born at Minghui Pig Company in Sanhe City, Hebei Province. At that time, all the people present were delighted. Professor Li Ning led Dr. Pan Dengke and Dr. Zhang Yunhai to see the long-awaited fruit on this day after more than a year of hard work.

According to the staff of Minghui Pig Company in Sanhe City, Hebei Province, the cloned pig is in good health at present. The pig company is its future home. It is living happily with its "surrogate mother." It still mainly drinks the milk of "surrogate mother" for a living. Every time it drinks milk, it crawls around the body of "surrogate mother" very cute. The cloned piglet will run when it is born. It will live and play with its foreign companions in the same living environment and food as other piglets. There will be no difference.

The birth of cloned piglets indicates that China has entered the international advanced ranks in this research. It is understood that only Britain, Japan, the United States, Australia, South Korea and Germany have previously obtained somatic cloned offspring of pigs. China is the seventh country to obtain somatic cloned offspring of pigs.

Three batches of experiments bred a cloned pig

From the biological point of view, cloning is an artificially induced asexual reproduction or asexual reproduction of plants. A clone is a multicellular organism genetically identical to another organism.

Somatic cell cloning refers to the process of using certain equipment and technical means to recombine embryos in vitro from somatic cells of animals and oocytes that have removed nuclear genetic materials, and then implant the recombinant embryos into the uterus of surrogate mothers at specific developmental stages to complete development and produce genetically homogeneous offspring with somatic cell donors.

According to Dr. Pan Dengke, the main scientific researcher in charge of the project, when Professor Li Ning handed over this difficult subject to him and Zhang Yunhai, they didn't expect to have today's results, because at that time there were already several laboratories in China doing experiments on cloned pigs, and some laboratories had already done this step of transplantation but didn't achieve pregnancy, blastocyst rate reached 20%, which is quite difficult in China.

Dr. Pan said that at that time, he only thought that if the blastocyst rate could surpass them by 20%, he would be satisfied. Blastocyst rate is a measure of the level of early cloning technology in a laboratory. Later, the blastocyst rate far exceeded that of other laboratories, so that transplantation was achieved. At this time, the preliminary work had been done very well, so the staff of the research group risked failure and thought that animals must be cloned, but this road was not smooth sailing.

Dr. Pan also told reporters that the research group carried out a total of three experiments, respectively in January, April and May this year, the research group for the first time is the laboratory construction of cloned embryos implanted into 10 white sows for pre-test, but did not succeed, the second time to 3 sows implanted cloned embryos, only one pregnant, the last time is to 2 sows implanted cloned embryos, one of them pregnant 21 days later aborted. These three trials did not negate their efforts.

At 10:50 a.m. on August 5, the sow pregnant in April finally gave birth to three black piglets after 116 days, but only one survived and the other two died due to abnormal phenomena.

According to Dr. Pan, the main reason for piglet death is that the current cloning technology is not very mature, the mortality rate of cloned animals in the world is very high, the current cloning technology can only clone individual animals, but how to make cloned animals very healthy has not been studied yet. Many animals will have abnormal phenomena after birth. For example, two of our cloned piglets died this time. One of them had an unhealed abdominal cavity and all its internal organs were outside. The other one was stillborn. Its forelimbs were relatively long and some organs were not well developed. This phenomenon is still relatively common in the world, and now scientists are not very thorough in this area. In recent years, the hot spot is on cloning mechanism.

How difficult is cloning pigs?

Related information reported that Taiwan, with the help of the United States, has produced somatic cloned pigs. This time, however, it was done by the Chinese themselves.

Experts said that at that time Taiwan was using somatic cells from sow ears as "nuclear donors" and then transplanting them to enucleated egg cells for "nuclear transplantation" projects. Mainland scientists, on the other hand, used Chinese experimental miniature pig fetal fibroblasts, which are more common internationally. This proves that we have reached the international average in cloning technology.

From the cloning technology, cloning pigs and cloning cattle, sheep than, in what aspects of its difficulty performance? Dr. Pan Dengke introduced that cattle and sheep belong to singleton animals. People have studied cattle and sheep relatively more and more thoroughly, and the operation requirements of egg cells of cattle and sheep in vitro are not very high. Pigs belong to multifetal animals, pig eggs are particularly sensitive to low temperature, in vitro temperature requirements at about 30℃, can not deviate too much, otherwise it can not be tested, and the quality of eggs in vitro maturity is also very poor, the time required is relatively long, so it is not easy to survive. For multifoetal animals, the number of cloned embryos injected into a surrogate embryo mother is much higher than for cattle and sheep. More than 100 cloned embryos are usually transferred in the early stage. So pig cloning may be relatively difficult in this respect.

South Korea recently born cloned dog and cloned pig than, its difficulty and performance in what aspects? Dr. Pan explained that the eggs of dogs and pigs are relatively black, not easy to nuclear, the biggest difficulty of cloning dogs lies in its eggs are not easy to control, in China to see the difficulty of cloning pigs is equivalent to the difficulty of cloning dogs internationally.

Prospects for cloned pigs

Internationally, cloning technology has shown broad application prospects. Cloning technology will be applied in four aspects: breeding excellent livestock breeds and producing experimental animals; producing transgenic animals; producing human embryonic stem cells for cell and tissue replacement therapy; replicating endangered animal species; and preserving and disseminating animal species resources.

As for the prospect of pig cloning, Professor Li Ning, the leader of the research group, said that it is of great significance to carry out somatic cell cloning of pigs, which can provide ideal materials for human xenotransplantation research and disease model development in medicine, and enrich the means of improving local pig breeds and preserving local excellent pig breeds in agriculture.

Pig organs are considered as ideal organ donors for human xenotransplantation because they are similar to human organs in physiological function and morphology. Scientists believe that by genetically modifying pig cells and then cloning large numbers of genetically modified pigs, organs suitable for transplantation can be obtained. The birth of the first somatic cloned pig will lay a solid foundation for the in-depth development of xenogeneic organ transplantation, high-quality pig breeding and local improved pig breeding in China. In the near future farms for cloned pigs are likely to become providers of transplant organs.