According to basic genetic principles, if certain genes help parents survive and reproduce, the parents will pass those genes on to their offspring. And some recent studies have shown that the real situation is much more complicated: genes can be turned off or silenced in response to environmental or other factors, and these changes can sometimes be passed from one generation to the next. This phenomenon is called epigenetic inheritance, and it is not yet well understood. Geneticists at the University of Maryland have proposed for the first time a specific mechanism by which parents can pass on silent genes to their offspring, and this silence can be maintained for more than 25 generations, PhysOrg.com reported on Feb. 3 (Beijing time). The discovery could change the understanding of animal evolution and help design a wide range of therapies for genetic diseases in the future. The related paper is published online Feb. 2 in the Proceedings of the National Academy of Sciences “Biologists have long wondered how much information from the environment is passed on to the next generation, and this mechanism shows for the first time how this happens at the level of animal tissues.” says Anthony Jose, associate professor of cell biology and molecular genetics at the University of Maryland. They studied a roundworm called Cryptobacterium hidradenum and got its nerve cells to produce double-stranded RNA molecules (dsRNA) that matched specific genes. dsRNA molecules can move between somatic cells and silence that gene when their sequence matches the corresponding cellular DNA. They discovered this time that dsRNAs can also enter germ cells and silence the genes in them. More surprisingly, this silencing can be maintained for more than 25 generations. If this mechanism is also present in other animals (including humans), it suggests that there is a completely different way for species to evolve in response to their environment. “This mechanism gives animals a tool to evolve much faster.” Jose said we still need further corroboration, and if animals use this RNA transport to adapt to their environment, it means we have to re-understand the evolutionary mechanism. Long-term, stable silencing effects are critical in developing therapies for genetic diseases. For more than a decade, researchers have been looking at a process called “RNA interference” (often called RNAi) as a potential gene therapy that can target any disease gene with paired dsRNA. The biggest hurdle is achieving stable silencing so patients don’t have to repeatedly use high doses of dsRNA. “RNAi is promising as a treatment, but efficacy declines over time and with cell division.” Specific dsRNAs in Ascaris neuronal cells, Jose said, may have certain chemical modifications that make gene silencing stable for many generations. Further study of such molecules could help address the efficacy of RNAi therapies. Jose also pointed out that there are huge differences between roundworms and humans. Mammals, unlike simple animals, are genetically capable of reprogramming silenced genes every generation. On the surface, this appears to prevent epigenetic inheritance, whereas previous evidence suggests that the environment can also cause some intergenerational inheritance in mammals. Their study helped uncover the cause of this intergenerational inheritance. Certain genes can be really bland and can be silent for more than 25 generations. So it seems that mega handsome parents give birth to children who don’t look so good to the audience, and shouldn’t always suspect that people have had plastic surgery. This new study by American scientists is important not only to provide new ideas for the treatment of genetic diseases, but also to provide us with an explanation of the powerful adaptive capacity of living things. In order to cope with the unpredictable, biological succession, you can not rely solely on the DNA set of magic. We need several hands to grasp, several hands must be hard. The genes have survived for billions of years, and there are more “caves” than we can imagine.