Non-genetic inheritance

Scientists have described the mechanism of extracellular inheritance in nematodes

Sofia Dolotovskaya, N+1

Scientists from the University of Maryland at College Park have described extracellular RNA inheritance with preservation of regulatory functions in nematodes. The article was published in the journal Proceedings of the National Academy of Sciences (Marré et al., Extracellular RNA is transported from one generation to the next in Caenorhabditis elegans).

The roundworm (nematode) Caenorhabditis elegans, one of the most popular model organisms in biology, was used in the work. Nematodes were fed with bacteria that synthesized double-stranded RNA, then bacteria were removed and the effect of these RNAs was observed in the descendants of nematodes.

It turned out that the RNA fed to nematodes is directly transmitted to their descendants. Fluorescent labeling of RNA showed that from the extracellular space they, together with the yolk substance, enter the oocytes and then accumulate in the embryos. After that, they enter the cytosol of the cells of the embryos, which causes silencing (suppression of gene expression) in the offspring.

Video from the University of Maryland press release
Discovery by UMD Biologists Reveals a Key Mechanism of Non-Genetic Inheritance – VM

Transmission occurs even when nematodes do not have complementary DNA sequences. The RNAs passed on to the descendants are then distributed among the cells, where it causes silencing. Interestingly, extracellular RNAs can also be transmitted to descendants without entering the cytosol. The authors suggest that in this case, the RNA remains in intracellular vesicles.

It is known that extracellular RNAs can accumulate in the human circulatory system, change their properties during diseases and potentially act as signaling molecules. However, their origin and purpose remain rather poorly understood. Once inside the cells, extracellular RNAs can regulate the expression of genes that have complementary sequences to them. Thus, it was previously shown that the introduction of RNA to some model animals can cause silencing of genes that have complementary RNA sequences, and this silencing is often preserved in the next generation. Scientists assumed that such silencing is the result of chromatin modification, DNA methylation or the formation of secondary RNAs, which are then passed on to descendants.

As the authors of the article note, in their work they have shown that extracellular RNAs are directly transmitted to the next generation. The mechanism by which extracellular RNAs transmit information regulating the work of genes to descendants explains how the experience acquired by animals during life can be passed on to the next generations.

Portal "Eternal youth" http://vechnayamolodost.ru  20.10.2016