Huang Junjie, an associate professor of biology at Sun Yat-sen University in China, and his collaborators broke this situation on April 6th at 5438+08. They reported for the first time in the world that human sex cells were genetically modified to obtain early embryos. A stone stirs up a thousand waves, and the attention aroused by this research has been fermenting recently.
Why does this technological progress cause great ethical controversy? Once gene technology is applied to sex cells, it may not only lead to "individual customization" of genes, but also affect the evolution of generations and even human beings. "Mr. Sai" will publish many articles on this, and different opinions are welcome to contribute. In the first article published today, Wang Chengzhi, an assistant researcher at the Institute of Biophysics, Chinese Academy of Sciences, believes that this technological progress has opened a Pandora's box, and the consequences may be unpredictable.
Wang Chengzhi (Assistant Research Fellow, Institute of Biophysics, Chinese Academy of Sciences)
On April 18, Huang Jun, an associate professor of biology at Sun Yat-sen University, led a research team at Protein &; Cell magazine published a paper, which reported the research progress of transforming human embryos through gene editing technology for the first time in the world. In this study, the research team modified the HBB gene (encoding hemoglobin) in human trinuclear fertilized eggs. A stone stirs up a thousand waves, and the international scientific community has quickly made different reactions to this research, and the ethical concerns caused by this research are also constantly fermenting.
Hereditary disease: endless defects
In the paper published by Huang Jun in the research group, they modified the HBB gene encoding globin in fertilized eggs, and the mutation of this gene will lead to a common genetic disease-β thalassemia.
This disease can lead to severe anemia, dysplasia, bone changes, and even neonatal death. There are many similar genetic diseases, a large part of which are familial. These diseases afflict the whole family from generation to generation, as if their ancestors had some insoluble curse.
Before the 20th century, people's understanding of these diseases was very superficial, and there were almost no countermeasures. To make matters worse, the custom of consanguineous marriage was very popular in ancient East and West. /kloc-In the 6th century, charles ii, a prominent heir of the Spanish Habsburg dynasty, suffered from various genetic diseases due to long-term consanguineous marriage, especially due to physical defects and no children, which eventually led to the rapid decline of the Habsburg dynasty. In ancient China, consanguineous marriages often occurred. A famous example is that Emperor Wu of the Han Dynasty and his empress Chen Ajiao are cousins.
Obviously, consanguineous marriage leads to the inheritance and accumulation of family genetic defects, and intermarriage between people with different genetic backgrounds will continue to "dilute" genetic defects. However, even if only one parent's chromosome contains a genetic defect gene, the possibility of his offspring inheriting the gene is still as high as half. Obviously, in order to completely eliminate a genetic disease in a family, it is necessary to ensure that all babies born do not carry the diseased gene, and the fertilization process in vivo is random under physiological conditions.
20 14 Peking University Qiaojie, Xie Xiaoliang and Tang Fufu cooperated to help a couple with genetic diseases select embryos without pathogenic genes and known mutations in vitro by using polar single cell sequencing technology, so that their babies can get rid of the "family curse" completely. This is a "milestone" breakthrough in the history of genetic diseases, which makes human beings end the family's pathogenic genes at the individual level for the first time.
The difference between this work and Huang Jun's team work is that it is only a process of artificial selection of fertilized embryos and does not touch the ethical red line of artificial embryo transgenic. And this red line is no less than the dividing line between human beings and the "creator". Beyond it, humans may enter another world that transforms their own species.
Transgene: The Hand of God
Humans have probably never stopped thinking about where they come from and why they are human, because different cultures can find similar stories: one (or more) super powerful "God" created all species, including people. Other similar stories can be found in these fairy tales with different cultural backgrounds. For example, some "gods" can transform existing species. For example, in ancient Greek mythology, Athena turned Medusa's long hair into a poisonous snake, and in Japanese mythology, there is even a legend that evil spirits entice men to plant their lovers' heads and get a face tree. It can be seen that human imagination can transform creatures across borders.
In fact, the desire of human beings to transform species has always existed and has been practiced. Today, animals and plants closely related to human beings, from potted plants in the office to pets at home, to various animal husbandry as food, are almost all transformed by human beings through various breeding methods (mainly through hybridization), and the principles behind all this were not recognized by human beings until the last century.
Today, two basic knowledge about biological traits have almost become common sense: all biological traits are determined by genes; The essence of gene is deoxyribonucleic acid (DNA) sequence. When human beings spy on the mystery of creation, the inevitable thing will happen: human beings want to transform themselves.
Humans want to transform themselves, as can be seen from the increasingly popular plastic surgery hospitals, but humans have never transformed themselves at the genetic level. Since the door of the "double helix structure" was opened, human beings have become more and more free to manipulate DNA. Tools such as restriction endonucleases, ligases and modified enzymes are constantly being discovered and modified, and scientists can splice DNA fragments in test tubes at will like Lego bricks; Polymerase chain reaction, DNA synthesis technology and DNA sequencing technology enable scientists to read and create new DNA sequences; The discovery of homologous recombination in cells allows scientists to edit the DNA in cells: first, prokaryotes such as Escherichia coli, then lower eukaryotes such as yeast were conquered, and then a series of model organisms such as fruit flies, zebrafish and mice were "taken down" by scientists one by one.
20 13 With the appearance of CRISPR-Cas9 technology, genetic modification has become a very low-cost and simple work, and any student with a background in basic molecular biology can learn and operate it in a short time. At this point, the "hand of God" seems to be in the hands of human beings: we have the ability to transform the genes in human cells and even change the genes in embryos, so as to get the individuals we want.
With beautiful imagination, technology can make everything sound beautiful. The scientific community has also become enthusiastic about genetic modification (known as gene editing in the industry), and the good news comes one after another: scientists have successfully removed the viral DNA from the latent cell model of HIV, scientists have successfully knocked out the oncogenes of cancer cells, and scientists have successfully transformed the genetic defects in human stem cells ... Scientists seem to have done everything except gently push open the last door.
Mutant: Pandora's box?
The movie "X-Men" imagines that all kinds of mutants have appeared due to genetic evolution, and the conflict between mutants and ordinary people has plunged the world into various disasters. With the maturity of gene editing technology, genes can be artificially "evolved", which may make some imaginary plots in movies come true.
Imagine that if human embryonic genes can be edited at will, many genetic diseases can be completely eradicated at first, but humans will not be satisfied with this, because they still hope to obtain "better" genes. For example, some parents may want their children to have genes such as "smarter", "healthier" and "more beautiful". Once genetic technology is applied to embryos, there may be "personal customization" of genes. Just as plastic surgery was first used in medicine to repair serious defects or deformities caused by diseases or trauma, it inevitably became a self-customized way. Just like a beautiful face in a Korean beauty contest, who knows if it will reappear at the genetic level?
If transgenic only stays in artificial selection or even creates "better" genes to pass on to future generations, the world will only be a more homogeneous individual. But if this Pandora's box is opened, the consequences may be unpredictable.
We must not forget that there are always some crazy people among human beings. When they master certain resources, they will trample on human nature. During World War II, Hitler admonished his men: "We should do this to hundreds of millions of stupid Slavs: transform the best of them according to our requirements and isolate the rest in their own pigsty." Even though human civilization entered the 2 1 century after the tragic world war, extreme religious forces still ran rampant in many places. Imagine what the world would be like if some of them mastered gene editing technology and applied it to humans.
Science and Ethics: Where Will Mankind Go?
Bernard Shaw, an Irish playwright, once famously said, "There are two tragedies in life. One is not getting what you want, and the other is getting what you want." Scientists have spent a lot of energy to develop gene editing technology to the present height. When generations of scientists saw a glimmer of hope to eliminate human genetic diseases, did human beings push the door into the forbidden area outside the "paradise" or think twice before acting? This will determine the future of mankind.
Science is pure, just as Faraday compared science to a newborn baby. But the baby will grow up eventually. The terrible thing is that once he grows up, he will no longer listen to his parents. It may become a saint or a devil. Just as human beings created wealth, now wealth is also controlling human beings. If science cannot be tied to the ethical red line, it may become a runaway wild horse.
1996, the birth of "Dolly" cloned sheep marked the beginning of human cloning of higher organisms. In 20 10, craig venter, a "scientific madman", synthesized the artificial creature "Synthia" for the first time, which indicates that human beings can create new species. Now, we are standing in the forbidden area of transforming human beings-our own species, and ethics has never been so important. Today, most countries have passed laws prohibiting human cloning. Maybe it's time for our legislators to face up to this problem.