The microscopic roundworm C. elegans lives for only about two to three weeks, reaching maturity in three days, then reproducing for a few days before beginning to age. This short life cycle makes it an ideal model for studying rapid aging, as researchers can follow its entire life cycle in just a few weeks.
On the fifth day of the worm's life, after it has finished passing on its genes to the next generation, a sharp decrease in its ability to sense diacetyl, the chemical compound emitted from its bacterial food source, is observed.
Researchers created worms carrying random gene mutations to test their ability to smell food. Most of the worms lost their sense of smell after reproduction, while those carrying a mutation in the nhr-76 gene retained their sense of smell, confirming the role of this gene in sensory deterioration.
The nhr-76 gene produces a protein that suppresses genes responsible for detecting food odors within sensory neurons. It is believed that this protein receives an age-related chemical signal to activate, leading to the worms losing their ability to smell food after reproduction.
Researchers propose two possibilities for the existence of this gene:
Its effect appears after reproduction, and therefore natural selection cannot get rid of it, because the organism has already passed its genes on to the next generation.
Sensory deterioration may be programmed to reduce competition for resources between older worms and younger generations, increasing the chances of offspring survival.
Most aging research focuses on the accumulation of damage, but this study highlights the existence of programmed genes that determine the decline of specific functions after reproduction ends. Since similar genes exist in mammals, these findings provide an important model for studying programmed aging in other animals and potentially humans, although similar mechanisms in humans have not yet been established.
The study was published in the journal Aging Cell.
