动物实验,RNA z-bo 2020-09-29 457

　　Octopus, squid, and squid usually do not strictly follow the genetic instructions of DNA, but use enzymes to remove a specific base A (adenosine) in RNA and replace it with another base I (inosine).  Most animals rarely use this process called RNA editing to encode proteins, but octopus and other octopus scalps edit RNA with more than half of the transcribed genes. In a new study, researchers quantified and explained the extent of RNA editing in cephalopods, and found that this genetic strategy significantly limited the evolution of the cephalopod genome. Related research results have been published in the recently published "Cell" magazine.

　　Previously, scientists discovered that octopuses use RNA editing to quickly adapt to temperature changes. Most RNA transcripts of squid neurons contain these edits. In this new study, the researchers hope to discover how these editing processes evolve in the head sheath lineage and affect the evolution of these animal genomes.

　　In fact, vertebrate cells can also perform RNA editing, but it is rarely used. Humans have 20,000 genes, but only dozens of RNA editing sites encode functional proteins. Researchers estimate that squid also has about 20,000 genes, but at least 60,000 active RNA editing sites. Eli Eisenberg, a biophysicist at Tel Aviv University in Israel, said: "Basically, this is a protein that does not encode DNA. It does not exist in the genome sequence. In other words, for these scalps, this is no exception. It is the rule. In fact, RNA editing is very rare, so it is not regarded as the "central rule" of genetics. Part. The co-author of the paper, the head and leg neurobiologist at the Woodsaw Institute of Marine Biology, USA Ya Rosenthal (Joshuaosenthal) said: "Watson and Crick discovered that genetic information is stored in DNA, so they believe that all information is stored in DNA. It is faithfully copied into another molecule (i.e. RNA), and then people usually think that this is a very faithful process, but squid RNA is not always the case. In fact, this organism has RNA information. We have developed an effective manipulation method. "

　　Analysis of various head sheaths revealed that this RNA editing mode exists in two octopus species. Among the common cattle fish and squid species, they all belong to the cephalopod class and are known for their complex predatory and social behaviors. However, when the researchers checked for signs of RNA editing in Nautilus, they also found that it was more closely related to octopuses, and the level of RNA editing was very low. For comparison, they also found that the level of RNA editing in the California sea hare mollusk is also very low.

　　In addition, extensive RNA editing has powerful evolutionary results. NA editing enzymes only act on base pairs surrounded by large RNA superstructures. If the bases on either side of the target are mutated, the organism may lose the ability to edit the target. In addition, the researchers also found that octopus and squid cannot tolerate DNA mutations in RNA editable genes, thus giving up the frequent mutations of genomic DNA and choosing RNA editing. done

　　"We usually use it to answer some challenges that consider evolution. Why not use RNA encoding?" Eisenberg said, "NA editing is widely used. There is an example of what will happen after completion. We know that this has a price, a price. It is to slow down the evolution of the genome. Skulls may choose RNA editing instead of genome evolution. Vertebrates have other options. They prefer genome evolution rather than RNA editing. Researchers also want to know whether RNA editing can bring octopus and its counterparts. Extraordinary intelligence. For example, octopuses are not only cunning when hunting, but also smart enough to avoid harsh sounds. They hide themselves by spraying ink, change the color of their skin to inform their peers, and learn through observation.

　　Currently, researchers are using octopus animal models to study whether RNA editing plays an important role in the behavior of the head pod. Experiments on the role of RNA editing in behavior require octopuses to grow well in the laboratory and be able to manipulate them genetically. Osenthal said: "NA editing is an elegant system that can add flexibility to genetic information, but understanding when and how to use it is a real challenge."