The title of this book is a book related to biological sciences, so students who do not have a high school biology elective three learning foundation may find it a little obscure.
What is the content of the high school biology elective three? The three elective textbooks are divided into five special topics -
Topic 1: Genetic Engineering;
Topic 2: Cell Engineering;
Topic 3: Embryo Engineering;
Topic IV: Safety and ethical aspects of biotechnology;
Topic 5: Ecological Engineering.
The content of this book is closely related to these topics.
In the compulsory high school biology course, we learned about genes, which are the genetic code in the organism, and all life phenomena of living things are related to genes. Genes are like the creation of the Creator in theology, which is an "heavenly machine" that cannot be leaked, and when human beings master gene editing technology, it means "breaking the heavens" and mastering the ultimate law of life.
Maybe you don't know much about gene editing, but you must have heard of disease-resistant rice, late-ripening tomatoes, teacup cats, mini pigs, etc. GMOs, and of course, you may hear more about whether GM crops are safe? Will gene therapy animals have irreparable side effects? Can gene therapy be applied to humans? Is it possible to edit human embryonic cells? And so on.
In this book, the authors (Jennifer Dodna and Samuel Sternberg) reconstruct the whole process of the birth of the gene-editing technology CRISPR and talk about their views on the ethics of gene editing and future applications.
The book is well organized and gives us a speculative understanding of gene editing.
Book Introduction:
In high school textbooks, we learned a lot about genetic diseases, albinism, phenylketonuria, congenital deafness, sickle cell anemia; polydactyles, and finger, cartilage hypoplasia; red-green blindness, hemophilia, trisomy 21, cat syndrome, etc., which are actually caused by wrong changes in human genes.
If you want to cure these diseases, you have to start with genes, which is the meaning and value of gene editing.
But the gene is in the cell, the cell is as small as dust, how can we edit the gene?
Scientists have tried a variety of ways, first of all, the use of viruses that can only survive and reproduce in the cell, the therapeutic genes are first introduced into the genes of the virus, and then transferred to the genes of the cells with the help of virus parasitism, but the virus will cause the body's immune response, and it is difficult to control where the virus inserts new gene fragments, which requires scientists to find new gene editing methods.
This editing method needs to first determine where the gene is edited, and then cut the gene in this position, and then replace it with a new gene fragment, just like the DNA strand is a rope, the rope is full of knots, each knot is extremely important, one of the knots in the rope is broken, then you need to use a pair of scissors to cut the knot, and then connect the new knot to the rope.
The authors' team developed CRISPR gene editing technology in 2012, which can achieve this function. This book details how CRISPR gene editing technology was born, and interested students recommend reading it carefully.
Gene editing technology has also been controversial since its birth and maturity, how should we view and apply gene editing technology? This is also the focus of the book.
The scope of application of transgenic technology is undoubtedly in organisms, and it is now being discussed in plants, animals and people.
Genetically modified crops can fight pests and diseases and increase crop yields, such as wheat that is immune to powdery mildew, soybeans with lower trans fatty acids, and cotton that is resistant to bollworms. These GM crops have excellent performance and quickly occupy the market as soon as they are introduced. As of 2015, 92 percent of corn and 94 percent of soybeans in the United States were genetically modified crops.
Although GM crops are used by humans, the safety of GM crops is still questionable, and many people believe that GM crops are unsafe.
Transgenic animals are less accepted than genetically modified plants. According to the New York Times survey, 75 percent of those surveyed said they refused to eat the genetically modified animal. Although scientists have now made transgenic pigs with higher lean meat content and transgenic goats with longer wool lengths, it is conceivable that the social acceptance of these genetically modified animals will not be very high.
The authors argue that, in fact, almost every food we eat has been artificially modified, for example, the random mutagenesis and hybridization techniques used in seed selection and breeding are essentially changing the genotype of animals and plants according to human needs. In this sense, the transgenic technology represented by CRISPR is essentially no different from the traditional breeding methods in the past.
Therefore, the authors are optimistic about the future application of genetically modified plants and animals. She believes that in the future, human beings will certainly need to solve many problems to ensure the absolute safety of gene editing technology applied to animals and plants, but people will certainly have the wisdom to solve these problems. Obviously, today's debate about the safety of genetically modified plants and animals will not stop easily, but in the future, the historical trend of their benefit to humanity is obvious.
Genetically modified animals not only provide meat and fur for humans, but even have the hope of saving many lives. In the United States, for example, there are now about 124,000 people waiting for organ transplants, but only 28,000 people get transplanted organs every year, and a large number of patients die while waiting for organs, and the lack of organ donors is a very real problem. Scientists envision that through gene editing technology, humans may be able to modify pig genes so that pigs can grow organs that can be used by humans. Moreover, the technology has already achieved preliminary results, scientists have used genetically modified pigs as donors for transplanted organs, one transplanted kidney is maintained in the baboon for 6 months, and a transplanted heart is maintained in another baboon for 2 and a half years. At present, this field has attracted a lot of investment. So, if gene-editing technology can really save human lives and provide valuable transplanted organs, it's really hard to reject it.
At this point, we have to start a more sensitive discussion, that is, how to view the application of gene editing technology in humans?
Gene editing has great potential for use in the medical field, but we must also be soberly aware that this technology is still a long way from mature application. For example, gene editing is not 100% accurate, and if it fails, the potential risks are high.
In CRISPR technology, guide RNA can recognize specific DNA fragments of 20 base lengths, but the scientists found that this recognition is not absolutely accurate, and if a similar fragment has only one or two different bases, CRISPR is likely to misidentify and make the wrong cut, a phenomenon known as off-target effect. In general, off-target effects are a very common medical phenomenon, such as looking at the instructions of various drugs, basically labeling side effects. But the off-target effect of gene editing is particularly dangerous, after all, the side effects of ordinary drugs will end after the drug is stopped, but once the gene editing is off target, the changes to the gene will never be recovered.
In addition to the off-target effect, the role and influence of various genes in humans is also very limited. The causes of many diseases are very complex, may be a combination of genetic variation and environmental factors, and simply editing genes may not be effective. What's more, there are secondary effects in gene editing, which may bring many unintended and complex consequences. For example, modifying the human body's CCR5 gene will theoretically enhance people's resistance to AIDS, but it will also increase the risk of West Nile disease; although some genes will increase the risk of Alzheimer's disease, studies have shown that these genes will also improve people's cognitive ability at a young age. In the face of the complex consequences of gene editing, how to make trade-offs? How to judge the risk? Deep reflection is still required from all sectors of society.
Let's go one step further. If the application of gene editing in medical treatment is still acceptable to most people, then the application of it to human embryos in an attempt to modify the genotype of human offspring is still in the ethical forbidden zone. In fact, scientists have edited a large number of embryonic genes of other organisms, so gene editing human embryos is no longer technically a problem. As we all know, He Jiankui, a former associate professor at southern university of science and technology, gave birth to two baby girls because of gene editing of human embryos in violation of the law, which triggered severe criticism and opposition from all walks of life, and he himself was sentenced to prison.
At present, all sectors of society have unanimously agreed to ban gene editing of human embryonic cells, mainly because there are still a large number of ethical issues that have not been solved. First, if we do gene editing human embryonic cells, then people will certainly not be satisfied with just changing harmful genes into normal genes, but will further want to turn them into better genes. Therefore, no matter how small the genetic gap between people is at the beginning, the wealthy class that can afford genetic modification will definitely let their offspring have better genes, which will inevitably lead to class solidification and gene solidification, and the rich people in the future will live longer, have better physical fitness, and have smarter brains. If this change lasts long enough, are the rich and the poor still the same creature? This would lead to serious and insurmountable social injustices.
For example, some genetic modifications will increase the content of erythropoietin in the human body, greatly improving the endurance value of athletes; other genetic modifications will reduce people's sleep time and increase the time they can participate in labor in disguise. If these changes do occur, is there any fairness in sports? Are people who are not genetically modified still socially competitive? Are minority genetic groups discriminated against? Will the diversity of human physiology and culture be challenged? Therefore, the authors argue that no one should currently do gene editing of human embryonic cells unless various social, ethical, and philosophical issues are discussed in depth and a global consensus is reached.
However, the author also makes her point that in the future, gene editing of human embryonic cells is certain to happen, and the question is only when and how. On the one hand, the success rate of gene editing will continue to improve with the improvement of technology, sooner or later it will reach 100% accuracy, which can avoid technical risks; on the other hand, each of us at the beginning of life, in fact, will carry 50-100 gene mutations inherited from the reproductive cells of our parents, and in the human body, there will be millions of mutations every second on average, so the change of human genes is actually a common natural phenomenon, gene editing just makes this change have directionality. So she believes that future parents have the right to use CRISPR technology to produce healthier children, as long as the process is safe and does not favor minorities.
The greater the ability, the greater the responsibility, in the face of the great tool to modify the code of life, we must think carefully before putting it into action, after breaking the heavenly opportunity, we need to control this amazing force, and we must also believe that human beings have the wisdom to make the right decisions.