动物研究 z-bo 2020-11-03 537

　　Some evidence from human famine and animal studies shows that hunger can affect the health of the offspring of starving individuals. However, people have never been clear how such an acquired trait is passed from one generation to the next. A new study of nematodes confirmed that starvation can induce specific changes in some small RNAs. These changes can be inherited for at least three generations, and this does not seem to involve any DNA.

　　This study, completed by researchers at Columbia University Medical Center (CUMC), provides interesting new evidence that genetic biology is much more complicated than previously thought.

　　Acquired traits can be inherited. This view can be traced back to Jean Baptiste Larmarck, who proposed that when individuals adapt to their environment and inherit the acquired traits to their offspring, species evolve. In contrast, Darwin believed that random mutations provide organisms with a competitive advantage and drive species evolution. In the case of giraffes, individual giraffes happen to have slightly longer necks and have a better chance of getting food, so they can have more offspring. Subsequent genetic discoveries supported Darwin's theory, and Lamarck's views were gradually forgotten.

　　Oliver Hobert, senior author of the paper, researcher at the Howard Hughes Medical Institute, and professor of molecular chemistry and molecular biophysics, said: “However, events like the Dutch famine during World War II forced scientists to re-examine acquired inheritance.” During the famine. Starving women who give birth to their children are particularly vulnerable to obesity and other metabolic diseases, as are their grandchildren. Some controlled animal experiments have also found similar results. A rat study confirmed that the father's long-term high-fat diet can cause their female offspring to be obese.

　　In a 2011 study, Oded Rechavi, a postdoctoral fellow in Dr. Hobert's laboratory, discovered that nematodes resistant to a virus can pass this immunity to their offspring for multiple generations. This immunity does not depend on the organism's genome, but is delivered in the form of small RNAs that silence viruses. Other studies have reported similar results, but none of them have addressed this issue: whether the biological response induced by the natural environment such as famine can be passed on to the offspring.

　　To answer this question, Dr. Hobert’s research team starved the nematodes for 6 days, and then tested the molecular changes in their cells. They found that the hungry nematodes produced a specific set of small RNAs (these small RNAs are involved in all aspects of gene expression, but do not code for proteins). These RNAs persisted for at least three generations, even when the nematodes were fed a normal diet. The researchers also found that these small RNAs target genes that play a role in nutritional intake.

　　Since these small RNAs are generated in response to starvation, they have passed from one generation to another. Dr. Hobert said: "From other studies, we know that small RNAs can be transmitted between cells throughout the body. Therefore, it is conceivable that small RNAs induced by starvation enter the reproductive cells of nematodes-that is, their sperm or eggs. When the nematode reproduces, these small RNAs can be independent of DNA and can be transmitted across generations in the soma of germ cells."

　　The study also found that the offspring of these starved nematodes live longer than the offspring of the control nematode. Hobert said: "We have not confirmed that starvation-induced small RNAs lead to longer lifespan-but there is an association. It is possible that these small RNAs provide nematodes with a means to control the expression of related genes in offspring.

　　These research results cannot lead to direct clinical applications. "However, they show that we should realize that besides DNA changes, there may be other things that have long-term effects on the health of organisms. In other words, what happens to a generation, whether it is famine or some other Traumatic events may be related to the health of future generations."