A terrible food poisoning attack is not an experience to forget. The commonly studied microscopic nematode Caenorhabditis elegans not only does he ensure that he remembers, but he genetically incorporates the threat of spoiled meals into his children to force them to stay clear as well.
What if by some misfortune one of these worms sinks anyway? The warning encoded in RNA can come out of its disintegrating body and can be picked up by any passing member of the species.
This remarkable means of memory transfer was seen by researchers at the U.S. Murphy Lab at Princeton University as part of a series of studies on inherited behaviors in the nematode.
Due to the existence of a fairly strict barrier between the germ cells that give rise to a new generation and the cells of the parents’ own body, it was once believed that events affecting the physiology of a father could not be imprinted on his offspring.
This vision has come out the window with discoveries of environmental stress in animals such as C. elegans changing the way genes are ignited not only in their offspring, but in the very children of their offspring … and so on, for generations.
Nor is it just a worm thing. The genes of the offspring of fruit flies and even mice can be modified by indications in the environment of their parents, effectively changing the biological functions of future generations.
Last year, researchers in the laboratory of molecular biologist Coleen Murphy published their findings C. elegans reactions to bacterial consumption Pseudomonas aeruginosa – An attractive source of food that quickly becomes unpleasant to your digestive system.
The team found that the worms absorbed RNA strands from their toxic food through the intestines, among which was a stretch of non-coding RNA called P11.
This nucleic acid slip was found to bind to a corresponding code in the genome of the worm, a gene called maco-1, which was already known to play a role in sensory perception. As a result, the worm “learns” to avoid itself P. aeruginosa in the future.
Surprisingly, this change in behavior also affects the offspring of a mother worm, teaching at least the next four generations to avoid this particular microbial meal.
The latter experiment demonstrates that genetic memory is not strictly a family affair, with evidence that can be transmitted laterally from worm to worm.
Tragically, the teacher must first be dusted off.
“We’ve discovered that a worm can learn to avoid this pathogenic bacterium, and if we grind it, or even just use the medium where the worms swim, and give that medium or the lysate of the worm crushed to naive worms, those worms now “learn” to avoid the pathogen as well, ”Murphy says.
Research on nematodes unable to learn this avoidance trick suggested that, despite the established role of maco-1 in preventing P. aeruginosa, only the presence of the gene could not explain why the behavior was inherited. Something else was happening.
Therefore, the team looked for other factors behind the peculiar neurological adaptation.
(Murphy Lab)
The main suspect was a traveling “jumping” gene called Cer1, which is already known to have the proper characteristics to move from one part of a genome to another like a virus.
“What we discovered is that a retrotransposition called Cer1 that forms viral-like particles seems to carry a memory not only between tissues (from the germ line of the worm to its neurons), but also between individuals,” says Murphy . Worms that naturally did not have Cer1, or had edited it, simply could not resist being bitten P. aeruginosa.
All this learning experience is not without risks. The jumping behavior of the retrotransposon can also cause damage as it is inserted into parts of the animal’s genome, suggesting that there must be a benefit to its costs.
Fascinating as they are now, the suggestions that inherited behavior-altering experiences can be inherited would have been surprisingly controversial half a century ago, when American animal psychologist James V. McConnell rose to fame — and infamy — for suggestions that worms plans could inherit memories by consuming other, more polite worms.
McConnell’s chapter in the history of biology has since influenced the debate over the permeability of this barrier between parents and children, and whether the experiences of the world of a generation can directly affect the way it is approached. the next.
It is still being explored to what extent this can happen in humans, but there are captivating signs that we are not exempt either.
This research was published in Cell.