动物造模 z-bo 2020-09-25 348

　　When a child puts a toy in his mouth, an adult will usually say: "I am sick because of the bacteria." He may not hear it at that time, but gradually began to stop eating the toy. Other animals cannot talk to humans and their offspring, which does not mean that they cannot explain the potential danger to future generations.

　　Caenorhabditiselegans (Caenorhabditiselegans) are very intelligent animals. They feed on bacteria such as empyema, which can cause nematode disease under certain environmental conditions. In 2019, researchers at Princeton University discovered that when a mother becomes ill with pyuria, she avoids the bacteria. Not only that, the fourth generation avoided this situation. After 4 generations, this avoidance behavior disappeared. Nematodes have been extensively studied for a long time, and the identity of every cell in the body (neurons, muscle cells, intestinal cells, etc.) is well known. However, this complex behavior passed down from generation to generation surprised researchers. Subsequent studies have shown that this behavior is limited to pathogenic suppuration. So how do nematodes know exactly what bacteria they are eating? In order to study this problem, the researchers added a variety of substances isolated from purulent bacteria to the bacteria and used harmless bacteria to feed the nematodes.

　　The substances they add include metabolites of purulent bacteria and genetics (DNA, RNA, protein, etc.). Colleen Murphy, a professor of molecular biology at Princeton University, said: "Unlike our initial expectations, the signal does not come from bacterial metabolites, but is related to small RNA produced by bacteria, especially the pathogenic state of bacteria." They found Genetic avoidance behavior requires a specific non-coding RNA called P11. "P11 itself is a small RNA molecule that causes nematodes. I don't get sick," she added. Murphy and colleagues found that when the nematode eats bacteria, P11 is absorbed and processed by the nematode's intestines, and then invades the nematode's eggs and sperm. Since the mother of the nematode is male and female, it has two types of germ cells and can self-fertilize. in

　　After, P11 is sent to the neuron that controls the avoidance behavior. In this neuron, certain fragments of the nematode mRNA are destroyed, thereby preventing the nematode from producing a protein called macoylin. In this way, the nematode knows to avoid pathogens. The presence of P11 in the germ cells of the nematode ensures that P11 can be used in subsequent generations of the nematode.