Infographic: How C. elegans Transmit Stress Signals to Offspring

Exposing neurons of hermaphroditic C. elegans to high levels of either the Huntington’s disease–causing protein Q40 or the ligand Wnt triggers a stress pathway, the mitochondrial unfolded protein response (UPR^mt), in many of their cells, including their oocytes. The UPR^mt involves elevated copy numbers of the organelle’s genome and an accumulation of unfolded proteins (1). When researchers bred these animals with wild-type males that had not been stressed (2), they found that about 30 percent of the offspring continued to carry a “memory” of that stress, as evidenced by the UPR^mt in their tissues (3). This transgenerational inheritance, the researchers found, was mediated by Wnt. Hermaphroditic offspring with the strongest stress responses were allowed to self-fertilize until up to 90 percent of offspring showed the UPR^mt inherited from the experience of their ancestors—a “memory” passed down for as many as 50 generations (4). Worms...