Biologists first to observe direct inheritance of gene-silencing RNA

Recent research has shown that, in some species, parents' life experiences can alter their offspring. Being underfed, exposed to toxins or stricken by disease can cause changes in a parent's gene expression patterns, and in some cases, these changes can be passed down to the next generation. However, the mechanisms that cause this effect—known as non-genetic inheritance—are a mystery. 

New research from the University of Maryland provides a surprising possible explanation. For the first time, developmental biologists have observed molecules of double-stranded RNA (dsRNA)—a close cousin of DNA that can silence genes within cells—being passed directly from parent to offspring in the roundworm Caenorhabditis elegans. Importantly, the gene silencing effect created by dsRNA molecules in parents also persisted in their offspring.

The work, published October 17, 2016 in the online early edition of the Proceedings of the National Academy of Sciences, suggests that the mechanisms for non-genetic inheritance might be simpler than anyone had suspected.

"This is the first time we've seen a dsRNA molecule passing from one generation to the next," said Antony Jose, an assistant professor in the UMD Department of Cell Biology and Molecular Genetics and senior author on the study. "The assumption has been that dsRNA changes the parent's genetic material and this altered genetic material is transmitted to the next generation. But our observations suggest that RNA is cutting out the middle man."

"It's shocking that we can see dsRNA cross generational boundaries. Our results provide a concrete mechanism for how the environment in one generation could affect the next generation," Jose said. "But it's doubly surprising to see that a parent can transmit the information to silence a gene it doesn't have."