continuous exposure to male pheromones worked best, even shorter
exposure improved overall egg quality. Ruvinsky believes this result can
be explained by the animals' "shifting energy budgets."
outside the body, pheromones are chemicals that animals produce and
release to elicit social responses from other members of their species.
According to Ruvinsky, pheromones also inform animals about how to
budget their finite energy.
conditions are not conducive to reproduction, female animals will spend
resources and energy maintaining their overall body health, including
muscles, neurons, intestines and other nonreproductive organs. Sensing
male pheromones triggers downstream signaling from the nervous system to the rest of the body, causing the female animals to shift their energy and resources to increasing reproductive health instead. The result? Better eggs but faster decay of the body.
pheromone tricks the female into sending help to her eggs and
shortchanging the rest of her body," Ruvinsky said. "It's not all or
nothing, but it's shifting the balance."
Salvaging recycled eggs
female roundworms spent more energy on reproduction, they produced more
egg cell precursors from stem cells. And, in a seemingly
counterproductive move, most of these cells actually died. But Ruvinsky
says this is not a mistake but a cleverly designed advantage.
"The majority of egg precursors die, and the spare parts are
recycled to build better eggs," he said. "We think that is essentially
what's happening. Production is increased. Most egg precursors die, and
their parts are salvaged and recycled into a few, higher-quality eggs."
course, there are unfortunate trade-offs. When female roundworms
neglected the rest of their body to focus their energy on reproductive
health, they were more likely to experience early death. Ruvinsky said
this information, too, can advise future drug development for humans.
pheromones that roundworms use are not found in humans," he said. "But
the neurons they activate are very similar. We are working to design
pharmacological interventions that manipulate these neurons to improve
fertility while reducing the negative side effects. It remains to be
seen, but it's definitely worth trying."
More information: Erin Z. Aprison et al, A male pheromone that improves the quality of the oogenic germline, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2015576119