There may be disputes about when humans began domesticating horses,
but there is no argument that horses have helped shape human history. We know Chinese equine Veterinary Medicine, including herbal
treatments and acupuncture, dates back thousands of years, but there`s
no agreement on the date, or even century. We do know the year their
health and care became part of the formal curriculum of veterinary
colleges. The year was 1761 and the location was the first veterinary
school in the world, in Lyon, France. Equine anatomy as part of a formal
curriculum has been studied by veterinarians since then, for more than
250 years.
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This logic can confuse many people, and even some scientists are using it. I have watched a TV talk show with a famous rice breeding expert. While supporting the GM crops in general, he also expressed reservations about the crops containing the Bt gene. The reason is also that it can kill pests. Harmful to human health?
After watching this program, my respect for this celebrity was greatly reduced. The research literature on Bt can be said to be full of enthusiasm. He did not first look at it and asked questions on television. Because of his lofty prestige, he would mislead the general public. This is irresponsible.
He even forgot about this common sense: Because insects and humans have different physiological conditions, they can kill insects, but they are not necessarily harmful to the human body. Many vegetables and fruits contain natural insecticides and insect repellents. Insects are not eaten, but we eat special foods such as tomatoes, citrus, onions, garlic, peppers, peppers, and so on. Some of these natural insecticides and insect repellents may not be good for human health, but some are not only harmless to the human body, but may even be beneficial. For example, citrus contains citric acid, which is a natural insect repellent. It has been reported that it also has Anti-cancer effect.
Bt toxin protein is one of the safest natural insecticides on the human body. It comes from Bacillus thuringiensis (Bacillus thuringiensis, hence abbreviated as Bt) and is a protein crystal secreted by Bacillus spores called "endotoxin". This endotoxin is non-toxic. After the insects have eaten the spores of Bacillus thuringiensis, the endotoxin crystals dissolve in the insect's intestine and are processed by proteases in the insect's intestine to be activated into toxic toxins that bind to receptors on the surface of intestinal cells. , causing intestinal perforation of insects. As a result, insects no longer eat, and are starved to death after 1 to 3 days.
Long ago, this biotoxin was used as a biological pesticide to spray crops. The so-called "organic crops" and "green crops" are not biological pesticides such as Bt endotoxin. However, this biological pesticide is much more expensive than chemical pesticides. In 1981, the gene encoding Bt endotoxin was cloned. The gene is transferred to the crop cells. The transgenic crops thus produced can also secrete endotoxins. After the insects eat the leaves of the transgenic crops, they also eat endotoxins and will be poisoned. Therefore, the cultivation of insect-resistant transgenic crops can eliminate or minimize the use of pesticides. At present, the most cultivated pests are transgenic maize and transgenic cotton.
Why is Bt endotoxin nontoxic to humans and animals? There are several reasons for this. When we eat food, it is usually heated and cooked before it is eaten. Endotoxin is a protein. Proteins denature after heating. Experiments have shown that endotoxin loses its activity when boiled in water at 60 degrees Celsius for one minute. Even if it is eaten raw, it does not matter. Endotoxins can only be processed into toxic proteins in the alkaline environment of insects. However, the stomach environment of humans and livestock is acidic. The intestinal cell surface of the animals does not contain toxin protein receptors. Therefore, it will not poison. Endotoxins eaten by humans and livestock are digested and broken down like other proteins.
The United States has used Bt endotoxin as a biological pesticide for decades. It has been a decade since the planting of insect-resistant genetically engineered crops containing the Bt gene on a large scale. To date, no case of human or animal poisoning has been found. Experiments with rats and sheep also showed that eating Bt endotoxin does not affect the health of mammals.
Excessive chemical pesticide residues have always been a major hidden danger of food safety. Since the cultivation of Bt genetically modified crops can eliminate or reduce the use of pesticides, it can not only save costs, but also avoid pesticide pollution. It is of great benefit to the protection of the environment and health. In this sense, Bt genetically modified crops are more environmentally friendly, safer, and greener. "Greenpeace" does not care about the overuse of chemical pesticides, but arbitrarily opposes genetically modified crops. It is running counter to its "environmental protection" claim.
"Greenpeace" recently held a press conference and announced that they had discovered unlicensed GM rice in the Hubei region. These rice plants contain a toxic protein gene called Bt, which is resistant to the main pest of rice, the aphid. They put forward: "Do not eat insects, how can people eat it?"