That offspring inherit epigenetic patterns of modifications to gene expression that reflect the environmental exposures of their parents was a relatively recent discovery. The evolutionary world is just a little bit Lamarkian, in that the ability to steer the metabolic reactions of immediate descendants provides greater resilience to stressful environments. Short-lived species respond to mild stresses with extension of life span, presumably because this increases the odds of reaching a better environment in which offspring are more likely to survive. As shown here, that extension of life span fades for descendants if the stress is maintained over generations. There is at that point a different set of cost-benefit considerations when it comes to balancing the fitness advantage of a metabolism that ages more slowly versus the fitness advantage of a metabolism geared for early life reproductive success at the expense of faster aging. Evolution has clearly produced a complex set of transgenerational reactions to common stresses in the environment a species finds itself in.
Epigenetic inheritance alerts naïve descendants to prepare for stresses that could still be present, whereas distant descendants return to a basal state after several generations without stress. However, organisms are frequently exposed to stresses successively across generations. We found that parental hypoxia exposure increased parental longevity, caused intergenerational lipid reduction, and elicited transgenerational fertility reduction that was dependent on generationally transmitted small RNAs.
Here, we find that Caenorhabditis elegans adapt to repeated generational stresses. We show that, upon two repeated generational hypoxia exposures, the life-span extension is eliminated, and after four repeated generational hypoxia exposures, the reduced fertility is eliminated. Transgenerational adaptation also occurred in response to changes in glucose availability. Transgenerational hypoxia adaptation is dependent on the H3K27 trimethyltransferase PRC2 complex, and we identified transgenerationally adapted genes. Our findings reveal that transgenerational adaptation occurs and suggest that H3K27me3 is a critical modification for adapting to repeated generational stresses.
Link: https://doi.org/10.1126/sciadv.adv9451
View the full article at FightAging
