Hailing a discovery that could have major implications for understanding heredity and evolution, researchers at Tel Aviv University have identified a nervous system mechanism that can transmit neural messages to future generations.
Researchers found a mechanism exhibited in nematodes — worms found in virtually all environmental habitats — that allows nervous system cells (neurons) to communicate with germ cells, which contain genetic and epigenetic information that is transmitted to future generations.
The study, led by Prof. Oded Rechavi of Tel Aviv University’s George S. Wise Faculty of Life Sciences and Sagol School of Neuroscience, was published Thursday in the peer-reviewed scientific journal Cell.
“The mechanism is controlled by small RNA molecules, which regulate gene expression,” said Rechavi. “We found that small RNAs convey information derived from neurons to the progeny (descendants) and influence a variety of physiological processes, including the food-seeking behavior of the progeny.”
The findings, Rechavi said, contradict one of the most basic dogmas in modern biology, where it has long been thought that brain activity could have no impact at all on the fate of future generations.
“The Weismann barrier, also known as the Second Law of Biology, states that inherited information in the germline is supposed to be isolated from environmental influences,” said Rechavi.
According to the study, co-authored by Rechavi’s students Rachel Posner and Itai Toker, the findings constitute the first time that a mechanism transmitting neuronal responses across generations has been identified.
“In the past, we’ve found that small RNAs in worms can produce transgenerational changes, but the discovery of a transgenerational transfer of information from the nervous system is a Holy Grail,” said Toker. “The nervous system is unique in its ability to integrate responses about the environment as well as bodily responses. The idea that it could also control the fate of an organism’s progeny is stunning.”
Researchers found that the synthesis of small RNAs in neurons is necessary for nematodes to be efficiently attracted to odors associated with essential nutrients, and search for food. The RNAs produced in the parents’ nervous system influenced this behavior, as well as the expression of germline genes persisting through at least three generations.
Nematodes that did not create the small RNAs exhibited defective food identification skills. When the researchers restored the ability to produce small RNAs in neurons, however, the nematodes once again moved toward food efficiently.
This positive effect was maintained for multiple generations of nematodes even though the offspring did not have the ability to produce small RNAs alone.“It’s important to stress that we don’t know yet whether any of this translates to humans. If it does, then studying the mechanism could have a practical use in medicine,” said Rechavi.“Many diseases might have some epigenetically inherited component. Deeper understanding of non-conventional forms of inheritance would be crucial to better understand these conditions and to design better diagnostics and therapies.”