Are you particularly disgusted that smelly mosquitoes keep you awake? Don't worry, maybe in the future, whether it's buzzing mosquitoes, food on a plate, pets snuggling at your feet, plants in the garden, or even cells in your body, your child's brain and body, all these can be transformed through genetic engineering technology to stop mosquitoes from sucking blood, make plants stronger, make pets smarter and make you and your children healthier.
The era of "designing babies"?
Many sci-fi works often mention the concept of "designing babies". For example, scientific lunatics want to control the world. They started with the fetus and provided it with super-power characteristics, so the baby with tailor-made super-power was born.
To some extent, these once impossible things have now become within reach. It relies on a gene editing technology (knocking out and adding specific DNA fragments) which is popular all over the world, and is called CRISPR/Cas9 system. If this technology becomes more mature, babies can modify their genes as needed before birth.
20 15 researchers in China used fertilized eggs that could not develop into babies for research, and then used CRISPR/Cas9 system to cut the human HBB gene in fertilized eggs, because the mutation of HBB gene would lead to β thalassemia. They injected 86 fertilized eggs, of which 7 1 fertilized eggs survived. Among the 54 samples tested, HBB of 28 fertilized eggs was cut. At this point, the idea of gene editing human embryos has become a reality.
Related technologies have been applied to plants and animals at present, and it is only a matter of time before editing human genes. However, this achievement may lead to legal and moral disputes.
A New Gene Editing Method
Although it is nothing new to modify human DNA manually in reality, there has never been a technology that can change human DNA as accurately and efficiently as CRISPR/Cas9 system. So, what is CRISPR/Cas9 system? How did it accomplish this tiny and precise work?
In fact, CRISPR/Cas9 system itself is a defense system, which is a tool used by some bacteria to deal with invading viruses, but scientists have found that this system can be easily changed into a tool for editing genes.
First of all, scientists borrowed a harmless virus equivalent to a "conveyor belt" to import targeted RNA, shear proteins and alternative DNA fragments into cells. Then, the guide RNA and the shear protein will attach to the specific position of the target DNA, where the shear protein will cut the double-stranded DNA, but the cell itself has the ability to repair DNA, and it will try to find similar DNA fragments as templates to repair this break. If the replaced DNA fragment is similar to the original fragment, the cell will install the replaced DNA fragment at the break. Therefore, by providing different DNA to repair the break, you can modify the base pair, delete a sequence, or add a completely new gene and so on. In this way, the genetic modification is completed.
By using it, we can see what genes are doing at a certain stage and easily "turn off" gene expression; It can introduce specific mutations to find out what makes cells cancerous or makes people sick; You can also adjust the genes of plants and animals to create more muscular drought-resistant corn and police dogs.
In the laboratory, using traditional methods to construct genes is not only cumbersome, but also expensive. The CRISPR/Cas9 system is a relatively simple and accurate gene editing method with relatively low cost. Only a few years after its invention, it has had a great influence in the field of biomedical research. Some scientists believe that one day CRISPR/Cas9 system may help to treat many genetic diseases, such as-
Hypothesis of babies without birth defects
Every family wants their children to be healthy and happy. For parents-to-be, the biggest worry is whether their unborn child is healthy. The methods to judge fetal diseases include prenatal examination (such as screening for mutation of pathogenic genes during pregnancy) and genetic diagnosis before embryo implantation, that is, screening embryos fertilized in vitro. Only when it is certain that the embryo will not have any problems will it be implanted into the mother's uterus. At present, genetic diagnosis before embryo implantation has been able to screen out thousands of serious genetic diseases.
However, if a child inherits the risk of two or more diseases, the genetic diagnosis method before embryo implantation becomes impractical. Because for the risk of two diseases, 3/4 embryos may not be suitable, and every time in vitro fertilization, only a few embryos can develop successfully, and it is obviously impossible to take out 3/4 embryos. In fact, even a few embryos that can develop successfully may have mutation of pathogenic genes.
In this case, instead of hoping to give birth to a healthy baby like buying a lottery ticket, it is better to use CRISPR/Cas9 system to edit the gene of an embryo and repair the "bad" DNA so that the embryo will not be discarded.
It can permanently change the genome of our offspring to eliminate diseases. By adding "beneficial" genes or mutant genes to improve the health level of babies with birth defects, people may live longer, healthier and happier.
Treat herpes
Everyone has a virus lurking in his body. For example, you are likely to be infected with human papillomavirus at some point. Human papillomavirus inserts its own DNA into the genome of a cell, so that it can be hidden for decades. If there is something wrong with your immune system, it will be activated and then infect more cells. The consequences may be fatal: human papillomavirus can cause diseases such as neck, throat, anus and cervix.
Herpes simplex virus can do similar things. Adding one or more copies of its own DNA to sensory nerve cells around the mouth or genitals will lead to skin ulcers around the mouth or genitals. Not only these two kinds, but also several other common viruses can be hidden in your body with this despicable trick.
At present, the best thing we can do is to help the immune system suppress virus activity. Now with the development of CRISPR/Cas9 system, there has been a breakthrough in the field of gene editing. Many studies have shown that in a small area of the body, such as around the mouth, CRISPR/Cas9 system can easily "attack" the target virus, herpes simplex virus, and destroy the virus genes in cells.
The dawn of AIDS treatment?
As we all know, HIV is a cunning retrovirus. Once it introduces its DNA into the genome of the host cell, it has a long incubation period and can remain dormant for many years. Although doctors can adjust the matching antiretroviral drugs to suppress the virus, if the treatment is stopped, it will revive again.
So, can CRISPR/Cas9 system be used to treat AIDS?
American neuroscientists use CRISPR/Cas9 system to eliminate HIV in experiments, but unlike herpes simplex virus and human papillomavirus, which are only distributed in a certain part, HIV is hidden in human memory T cells (a kind of human immune cells), and memory T cells are scattered in all corners of the human body, so it is not certain that CRISPR/Cas9 system can eliminate all HIV.
However, some scientists say it may not be necessary to eliminate HIV in all cells. Their idea is to use CRISPR/Cas9 system and existing antiretroviral drugs to restore the immune system of HIV-infected people, and finally cure AIDS, but the research needs to be deepened and developed.
But obviously, any genetic engineering technology has worrying risks, such as creating healthy babies, muscular police dogs and horns on farms, which will involve ethical and animal welfare issues; While improving the drought resistance, salt tolerance or growth rate of plants, plants will begin to spread and become invasive weeds, which will bring various ecological problems, including the extinction of local species. Perhaps the most controversial thing is that humans can use gene editing technology for non-therapeutic human body enhancement, such as modifying genes to increase muscle mass, height or intelligence, and create a unique "design baby" in the novel.
Genetic engineering technology is full of controversy, and how to treat these problems seems to have to wait for time to verify.
(This article is from the third issue of big science and technology * scientific mystery 20 16)