Researchers Discover How Worms Pass Down Knowledge Of A Pathogen To Their Offspring

When humans see their children about to eat something they oughtn’t, we can simply tell them, “Don’t eat that. It’ll make you sick.” Those who listen to this advice are spared the painful experience of learning that lesson for themselves. While other animals can’t sit their offspring down for a good talking-to, that doesn’t mean they are unable to instruct their descendants about potential harms.

For instance, the microscopic roundworm Caenorhabditis elegans feeds on bacteria such as Pseudomonas aeruginosa. However, certain environmental conditions can cause P. aeruginosa to change in such a way that it becomes pathogenic -- that is, it sickens worms that eat it. In 2019, researchers in the Murphy lab showed that when worm mothers are made ill by P. aeruginosa, they learn to avoid the bacterium. Not only that, but their offspring, all the way down to their great-great grandchildren, somehow also know to avoid the bacterium. After four generations, though, the transgenerational avoidance behavior disappears, letting the worms return to feeding on the bacterium once more.

C. elegans has been so intensively studied that we not only know the identity (e.g., neuron, muscle cell, intestinal cell, etc.) of every cell in its body, but also the order in which it appears during embryonic development. Nonetheless, the worm still manages to surprise us with complex behaviors such as transgenerational avoidance. What causes this behavior? Initial work by the Murphy lab showed that other types of pathogenic bacteria didn’t cause avoidance behavior in offspring, indicating the behavior is specific to pathogenic P. aeruginosa. Furthermore, the researchers showed that avoidance of pathogenic P. aeruginosa is controlled by one particular worm neuron. But several questions about the phenomenon remained, so the team continued to investigate.

Continue reading at Princeton University.

Image via Princeton University.