The self of the heavens has billions of clones

Chapter 144

R & D history
First transplant the nucleus of the donor cell containing the genetic material into the egg cell from which the nucleus has been removed, use microcurrent stimulation to fuse the two into one, and then promote the division and reproduction of this new cell to develop into an embryo. When the embryo develops to a certain extent After that, it is implanted into the uterus of the animal to make the animal pregnant, and then the animal with the same gene as the one who provided the nucleus can be produced.In this process, if the donor cells are genetically modified, the offspring of the asexually reproduced animals will undergo the same genetic changes.clone

Cloning technology does not require male and female mating, does not require the combination of sperm and eggs, but only needs to extract a single cell from an animal, cultivate it into an embryo by artificial means, and then implant the embryo into a female animal to give birth to a new individual.This cloned animal cultured from a single cell has exactly the same characteristics as the single-cell donor and is a "replica" of the single-cell donor.British scientists in England and American scientists in Oregon have successively cultivated "cloned sheep" Dolly and "cloned monkey".The success of cloning technology is called "historic event, scientific pioneering work" by people.Some people even think that cloning technology can be compared with the advent of the atomic bomb.

Cloning technology can be used to produce "cloned human beings" and "replicate" human beings, which has attracted widespread attention from all over the world.For human beings, is cloning technology sad or happy, a curse or a blessing?Materialist dialectics holds that everything in the world is a unity of contradictions and is divided into two.So is cloning.If cloning technology is used to "replicate" war madmen like Hitler, what will it bring to human society?Even if it is used to "copy" ordinary people, it will bring a series of ethical and moral issues.If cloning technology is applied to animal husbandry production, it will cause a fundamental change in the breeding and reproduction of excellent livestock varieties.If the cloning technology is used in the research of gene therapy, it is very possible to overcome those stubborn diseases such as cancer and AIDS that endanger human life and health.Cloning technology, like atomic energy technology, is a double-edged sword, the hilt of which is in the hands of human beings.Human beings should take joint actions to avoid the appearance of "human cloning" and make cloning technology benefit human society.

Cloning technology, also known as "biological amplification technology", has experienced three development periods: the first period is the period of microbial cloning, that is, one bacterium can quickly replicate thousands of bacteria that are exactly the same as it, thus becoming into a bacterial group; the second period is the period of biotechnology cloning, such as using genetic gene-DNA for cloning; the third period is the period of animal cloning, that is, a cell is cloned into an animal.The cloned sheep "Dolly" is cloned from the somatic cells of an ewe, using animal cloning technology.

In nature, many plants are born with the instinct of cloning, such as sweet potatoes, potatoes, roses and other plants that can be propagated by cuttings.The animal cloning technology has gone through the development process from embryonic cells to somatic cells.cloned sheep
Unfertilized eggs of some invertebrates (worms, some fish, lizards, and frogs) can also grow and develop into complete individuals under certain environmental conditions, such as chemical stimulation.This process is also known as cloning of the egg-laying female.

As early as the 20s, scientists in the United States used amphibians and fish as research objects and pioneered the technology of cell nuclear transfer, which can be compared to "civet cats for princes".The basic process is to first transplant the nucleus of the donor cell containing the genetic material into the egg cell from which the nucleus has been removed, use microcurrent stimulation and other means to fuse the two into one, and then promote the division and reproduction of this new cell to develop into an embryo. After the embryo develops to a certain extent (it takes about 50 days for the Roslin Institute to clone sheep), it is then implanted into the uterus of the animal to make the animal pregnant and produce an animal with the same gene as the donor.If the donor cells are genetically modified during this process, the same changes will occur in the genes of the offspring of asexually reproduced animals.The main difference between the "Honolulu technology" that successfully cultivated three generations of cloned mice and the technology of cloning Dolly sheep is that the genetic material in the cloning process is not cultured in culture medium, but directly injected into egg cells by physical methods.In this process, chemical stimulation is used instead of electrical stimulation to promote the fusion of egg cells. In 6, British scientist Willardson cloned a sheep using embryonic cells. Later, others successively cloned cows, rats, rabbits, monkeys and other animals.The birth of these cloned animals was achieved by using embryonic cells as donor cells for nuclear transplantation.This cloning technology is less difficult and more suitable for research.

The cloned sheep "Dolly" used mammary epithelial cells (somatic cells) as donor cells for nuclear transplantation. It opened a new page in the history of biological cloning and broke through the traditional method of using embryonic cells for nuclear transfer, making cloning possible. Technology has come a long way.Dolly has completely inherited all the genetic characteristics of the DNA of his biological mother's one-cell provider, the Dorset ewe, and is a [-]% "replica" of the Dorset ewe.

early research
The genetic makeup of all members of a clone is identical, except when mutations occur.Clones of natural plants, animals and microorganisms have long existed in nature. For example, identical twins are actually clones.However, the incidence of natural mammalian cloning is extremely low, the number of members is too small (usually two), and it lacks purpose, so it can rarely be used to benefit mankind. Therefore, people began to explore artificial methods. Produce clones of higher animals.In this way, the word cloning began to be used as a verb, referring to the act of artificially breeding cloned animals.

Currently, the two main methods for producing mammalian clones are embryo segmentation and nuclear transfer.The cloned sheep "Dolly", as well as various cloned animals subsequently bred by scientists from various countries, all used nuclear transfer technology.The so-called nuclear transplantation refers to the process of transplanting the nuclei of embryos or adult animals at different stages of development into enucleated oocytes through microsurgery and cell fusion methods to reconstruct the embryo and make it mature.Unlike embryo segmentation technology, nuclear transfer technology, especially continuous nuclear transfer technology, can produce unlimited genetically identical individuals.Since nuclear transplantation is an effective method to produce cloned animals, people often call it animal cloning technology.

The idea of ​​cloning animals using the technique of nuclear transfer was first proposed by Hans Spemann in 1938, which he called a "bizarre experiment", that is, from embryos (mature or immature) in the late stage of development. The nucleus, which is transplanted into an egg.This idea is now the basic approach to cloning animals.

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