Nerve cells can transmit messages to future generations not via the DNA, but by epigenetic changes
https://www.haaretz.com/science-and-health/worms-help-israeli-scientists-rewrite-basics-of-genetics-1.7345758For biologists, the discovery is shocking. “These findings go against one of the most basic dogmas in modern biology,” Rechavi says. “It was long thought that brain activity could have absolutely no impact on the fate of the progeny.” Evidently the nematode didn’t hear of the Second Law of Biology.
Excerpts: "Nematodes have just upended the Second Law of Biology, researchers at Tel Aviv University reported Thursday in the journal Cell. Using worms, Prof. Oded Rechavi, with Rachel Posner and Itai Toker, have proved for the first time that true epigenetic inheritance does exist.
A worm’s reaction to the environment can pass from generation to generation without change in the DNA itself. The team also discovered exactly how this nongenetic legacy is achieved.
“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.”
The Second Law of Biology, aka the Weismann barrier, states that inherited information in the germline (sperm and egg cells) shalt be isolated from environmental influences.But in the simple nematode C. elegans, progress was made in recent years. Mechanisms were identified that act in parallel with the DNA.
In this new study, Rechavi and colleagues show that the worm’s ability to seek food can be governed by inheritance from the ancestor’s neurons, causing epigenetic silencing of a specific gene in the progeny.
This gene was shown to control the decision of whether to forage (go look for food, leave your safe place) or whether to stay put and avoid the risk.
And what is the mechanism controlling the gene? It turns out to be a type of small RNA molecule made in the worm nerve cells.
A worm that can’t make the small RNAs can’t seek food.
But if that worm’s mother or even their grandmother could make the small RNA in the nervous system — then the worm can seek food.
The worm inherited the small RNAs from Mama, not via the DNA. Ergo, somehow Mama’s nerve cell conveyed the change to Mama’s germ cells.
The epigenetic effect can persist three to five generations in nature, even hundreds of generations if the worms are genetically altered, Rechavi says.
Their discovery upends a basic tenet of biology, the Second Law: Inherited information in the germline is supposed to be isolated from what happens in somatic cells (the cells of the body, not the germ cells) and from environmental influences.
In the lab, nematodes that couldn’t make the small RNAs exhibited defective food identification skills. When the researchers restored the ability to produce small RNAs in neurons, the nematodes moved toward food efficiently once again. This effect was maintained for multiple generations even though the progeny did not have the ability to produce small RNAs themselves.
For biologists, the discovery is shocking. “These findings go against one of the most basic dogmas in modern biology,” Rechavi says. “It was long thought that brain activity could have absolutely no impact on the fate of the progeny.” Evidently the nematode didn’t hear of the Second Law of Biology.
Link to the original study.
My comment: Epigenetic memory makes it possible for an organism to transfer valuable information from parents to offspring. The mechanism is very complex and points to design. Scientists are still wondering if this mechanism is present in mammalian cells. Of course it is. There are thousands of different short and long noncoding RNA molecules in human sperm, for example. Their job is to transfer epigenetic memory to children. This information is stored in histone epigenetic markers. Most of human traits and characteristics are inherited in this way. But gene-centric theory of evolution resists findings like this. That's why it's pseudoscience. Don't get lost my friends.
