Grandfather's inheritance
Biologists have described the transmission of genetic information outside of DNA through generations
Nikita Loginov, Naked Science
Scientists from the University of California at Santa Cruz (USA) have uncovered the mechanism of transmission of biological traits and traits beyond DNA molecules. It turned out that hereditary information can thus pass not only from parents, but also from grandparents, biologists write in the journal Proceedings of the National Academy of Sciences (Kaneshiro et al., Sperm-inherited H3K27me3 epialleles are transmitted transgeneratively in cis).
People noticed the similarity of offspring to their parents in ancient times, but only in the XIX century the monk-biologist Gregor Mendel and the nobleman Imre Festerik gave a scientific explanation why this happens. Inherited traits in the form of genes are encoded in DNA and RNA molecules that are passed down from generation to generation. The genes themselves usually do not change during the life of the organism, and the reason for the variability of new generations is that the genes of the ancestors (not only direct, but also more distant) are shuffled during sexual reproduction like a deck of cards.
For a long time, scientists believed that genes are the only mechanism for transmitting hereditary information. That is, there is no inheritance of traits outside of DNA and RNA. This means that the traits and properties that the body acquired during life cannot be passed on to its children. However, by the end of the XX century, biologists discovered that this was not the case: there was still an epigenetic channel for transmitting signs. The essence of his work is as follows: under the influence of various lifetime factors (for example, severe stress) The "activation level" of various DNA and RNA sites is changing. Because of this, the same genetic code can produce different results for a parent and his child.
American biologists from the University of California have studied one of these mechanisms using soil nematode worms (Caenorhabditis elegans). Under the influence of the epigenetic label H3K27me3, the DNA molecule is tightly packed, which makes some genes difficult to activate. Scientists removed this label from the chromosomes of nematode sperm and fertilized eggs with fully labeled genes with them in order to determine exactly what changes this would lead to.
As biologists expected, without H3K27me3, usually inactive genes were activated in the offspring. This led to various effects, up to the infertility of some worms. But the most interesting thing turned out to be that some genes were activated earlier than necessary — right in the germ tissue, whereas normally they should have started in already formed neurons. And this acquired pattern of gene activation was consistently passed on to offspring.
Nematode embryos with active and deactivated epigenetic label H3K27me3 / © University of California
According to Susan Strome, one of the authors of the study, any epigenetic changes in the germ line can potentially persist for many generations. This does not look like some strange feature of nematode worms, but rather a preserved epigenetic mechanism characteristic of animals in general, including humans.
Consequently, the development of an individual can be influenced by the life circumstances that his ancestors had to go through — not only directly to parents, but also to grandparents. However, it is not yet possible to test this hypothesis in humans: genetic experiments involving humans are prohibited.
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