What doesn’t kill you makes your offspring stronger
When a C. elegans nematode starves early in its life cycle, its offspring are more resistant to starvation in the next generation; however, this life-saving inheritance comes at a fitness cost for the worm itself, reveals research published in GENETICS.
Jobson et al. investigate the idea that lean experiences during early development cause organisms to anticipate a deprivation in the future and to prepare by undergoing molecular reprogramming. This hypothesis – termed the “thrifty phenotype” – says that these organisms would then thrive in lean conditions but suffer adverse outcomes in times of plenty. In fact, many researchers have explored the thrifty phenotype to explain the high incidence of type 2 diabetes and other metabolic abnormalities in individuals who experience poor nutrition during fetal development.
Better understanding the changes an organism undergoes to survive starvation – and how those changes affect the organism itself and its offspring – can help us understand how food availability (and perhaps even socioeconomic hardship) impacts public health.
And that’s where worms come in.
C. elegans has always been an interesting study in adaptive fitness; they have an alternative developmental stage called the dauer larva that allows them to go into stasis and survive harsh conditions like high population density and limited food. These worms are also capable of arresting development in the first larval stage when they hatch in the complete absence of food. Now, Jobson et al. have rigorously and systematically examined both the immediate and long-term effects of starvation on the worms and their offspring.
They starved the worms during the first larval stage and then gave them ample food. They found that starvation slowed their growth, resulted in fewer progeny, and made them more sensitive to starvation later in life – a result that actually goes against the “thrifty phenotype” hypothesis. Interestingly, progeny of the starved worms were more resistant to starvation, an effect which lasted two generations. The worms most severely affected by the initial starvation event were actually more likely to have offspring that were better adapted to adverse conditions.
More work is needed to understand the mechanism by which the starved worms can pass down starvation resistance, but epigenetic modifications are likely at play.
CITATION Jobson, M.A., Jordan, J.M., Sandrof, M.A., Hibshman, J.D., Lennox, A.L., Baugh, L.R. 2015. Transgenerational effects of early life starvation on growth, reproduction and stress resistance in C. elegans. GENETICS, 201(1): 201-212. doi: 10.1534/genetics.115.178699 http://www.genetics.org/content/201/1/201.full