The first time in human beings completely subverted the core mechanism of mammalian development in nature: no need for male mice, two mice can reproduce the descendants.
In 1982, two British scientists introduced rat growth hormone gene into mice, creating more than 1/3 super mice than normal mice. Since then, the latest developments in biology will attract extensive attention from time to time. A few years ago, cloning sheep, showing the nucleus nuclei nucleus nuclei nuclear nucleus in a mammalian animal can be replaced by body cells, which has triggered a series of loose storm. With the removal of Dollar, and the public is tired of cloning technology disputes, these hustle and bustle are only moving.
"Huiye Yi" and its one-necrhable baby
However, the gap left by Cloning Beige, now seems to have more dangerous successors. A article published by "Nature" magazine on April 22 made a mouse to become a new animal star, creating its Japanese scientist River Yeohong giving a cute name --- "Hui Ni Ji" Ji Ingraven is a princess born from the bamboo in Japan.
The cloning is only aseculent reproduction, and Dolly can be "parent" because it gives it the original nuclear sheep with parents, so from genetic perspectives, Dollar is just a modern biology version of the same egg twins. This time, "Hui Yi Yi" has been cultivated by Scientists from Tokyo Agricultural University, but there is no father, at least there is at least the father of the usual sense. Its chromosome is provided by two mothers. It can be said that this is the first time that human beings completely subvert the core mechanism of mammalian development in nature in the laboratory.
In general, the child of sexuality species is formed by providing distribution by both parents. Of course, people are also familiar with many species that can not have fathers, such as aphids and bees, which are called solitary reproduction. However, people have never seen a mammal in nature can be lonely reproduction, and "Huiye Ni" is one of the world's first batch of mammals without my father.
The "Hui Yue Ji" is not out of the vicious mentality or arrogance of biologists. In fact, scientists have cultivated "Huiye Ni Ji" to understand our own development mechanism, in order to truly understand what role in the development of the parents in the development process. The understanding of this role will be used to help us explain the hereditary diseases or phenomena that cannot be explained in conventional legacy, can be used to understand the crazy behavior of cancer cells, and can even be used to understand the two sexs "Capture" in embryonic cells.
Sexual reproductive species, usually diploid, that is, about half of the chromosome in the cell from the mother, and the other is from the father. This means that a variety of species in which sexually transmitted species, the number of chromosomes in the talent cell must undergo a process of decancing, so that the number is just half of normal cells, this process allows sexual reproductive species to 1 1 = 2 This formula is passed down. In this simple formula differ, other chromosomes have been considered substantially consistent, in other words, in other words, they can be replaced with each other.
This idea is indeed confirmed in some simple regenerative species, and scientists check the cells from female assigles before the nuclear fusion from male and female, replace it from males or opposite, so new The chromosome composition in the fertilized egg is actually provided by two fathers or two mothers.
However, this simple replacement method is that the fertilized eggs of mammals are unreasonable, and the fertilized eggs of this surgery have aborted in development. This means that if you want to get a female individual, then her two XX chromosome can not provide all from the father and cannot be provided by the mother, and each of the parents will come out. That's why "Hui Ni Ji" is so concerned: its two XX chromosome are from the mother, two different mothers, one of the mother's genetic composition and the ordinary mother are different, this is its success Key elements.
Not only successful scientific experiments will bring new knowledge, and the deeper understanding of nature is often from failed experiments. Biologists have this aware that at least mammals have a method for identifying chromosomes from parents. Specifically, the cells of the mammal are in the face of two identical genes on the homologous chromosome, and the cells can know their sources and typically only selectively express one of them. The method identified is to see if there is a small amount of a small methyl group in the base of the component C, if any, the gene is closed. The presence of the methyl is the sign from the fat party or the mother, which is called the gene's imprint. Not all genes need to be marked, but if the genes that should be marked do not bring the correct imprint, the consequence is that the child is either properly developed, or there will be some difficult generative disease. In the development of development, if these imprint changes due to accidental reasons, it will trigger a phenomenon that is difficult to understand. For example, in the same eggs, although there seems to be exactly identical genetic information, even a basic consistent living environment, it may have a huge difference, such as a health, and another mental illness. Gene imprints are accompanied by people, with age, these printers are also changing, and even changes in the mark and the possibility of aging may also be a high. However, before "Hui Yiji" appeared, all the idea of labeled parents from genetically imprints was just conjecture, and there was no solid evidence.
The study found that mammalian embryo development requires two genes (H19 and IGF2) expression, which of which the expression of the two genes is from different genders of chromosomes. The H19 gene expression from the mother's chromosome, while IGF2 expresses the chromosome of the father, causing this phenomenon because of the gene imprint. There is one part on the female chromosome to inhibit the expression of IGF2 to promote expression of H19 with an adjusted protein. However, in the parent chromosome, this regulatory protein cannot be combined due to the different printed, so that IGF2 is expressed, while H19 is suppressed.
The gene imprint occurs during the ripening of eggs. Early work in Hanoyou Hong Group suggests that the introduction of a chromosome component (i.e., yet imprints) can extend the survival time of unstruthous embryos. Further eliminates the H19 gene in an unscrupulous egg to develop embryos to develop. It may be because the toner protein binding site still exists, and the chromosome from an immature egg still cannot express the IGF2 gene as a chromosome from the father, thereby affecting the normal development of the embryo. After rejecting the H19 gene, the Hanoi team further removes the mandatory protein binding site, in theory, the chromosome from an immature egg is theoretically like the chromosome produces IGF2 from the parent. In the 371 embryos, there are 10 days of origin that it seems to be normal, 2 birth, one, "Huiye Niji", survived to the adult and gave birth to a mouse baby.
In the eyes of different people, the meaning of "Hui Yi Ji" may be completely different, but first we have to remember that "Huiye Ni" represents human beings, it is a step in the understanding of their own understanding, this step is far away. More than the birth of Dori. Some of the biological progress will inevitably involve human beings themselves. Regardless of this fanless "Hui Ni", it will make any guess. As a man, it is not necessary to panic. At least, so far, the safest and convenient way of prosperity is still the traditional germplasm, and the birth of "Hui Ni Ji" is also It is not to take precautions to the y chromosome crisis.
Relevant
Is it worrying?
For this achievement, Magnus, a bioethist of Stanford University, said: "This is a big step. We have always believed that you must have male and female chromosomes to reproduce mammals, and this is the first I really have the opportunity to break that point. "
As with cloning technology, some people are concerned that the technology is likely to be used in human prospects. Martin Bolu, a professor of Medical Genetics, Cambridge, believes: "In ethical, in favor of the argument and other arguments The situation encountered by cloning technology is roughly the same. Its safety is still lower or less to be observed. "Azim Suli, professor, said:" This is a result of a great result. Create these mice It takes perseverance and patience. However, this technology is used for human beings too complicated. "Anne Fernson, the clinical director of the auxiliary reproductive center, said that the results show that single genitation is only effective for the very small part of the mouse embryo, so" This doesn't mean that you can eliminate male. We still need the parent's chromosome to achieve normal development. " Simon BEST, Chairman of the Biotechnology Industry Association of Scotland, believes that the paper of Hanoi et al., "Just like cloning technology, another hazyproppy form can be implemented on experimental rats, perhaps can also apply to certain other breastfeeding Class animals. "BEST also pointed out that the success rate of" Huiye Niji "genetic engineering technology is even lower than the cloning technology used by the first cloning sheep, so this technology is more difficult to accept. Not safe, it is not possible to consider applications in human. "
Since we must first get a transgenic transformation of female to provide pecals like sperm, the river Yushan Hong himself believes that the technology will be used for human beings. Elissen Murdoch, Chairman of the British Fertility Association, also believes that the main value of this achievement is that "will help us understand the reasons for future imprints, and the innate abnormalities." Female Scientist in the University of Pennsylvania Medical School, Maryza Baltoli, said that the role of "bypass" the reproductive process of experimental rats can be "surprised" for the two genes of the experiment.
The next goal of the Heye Group is to use pigs to make single germ.
