How a Mother's Age Leaves a Molecular Mark on Her Offspring

A mother's age can shape the physical and behavioral traits of her offspring across much of the animal kingdom, from invertebrates to elephants, primates and humans — a phenomenon scientists call maternal age effects, most of which are negative. Researchers at the Marine Biological Laboratory are using tiny, fast-reproducing aquatic animals called rotifers to uncover the biological mechanism behind it.

"Maternal age effects are incredibly common, from invertebrates up through humans, elephants, other primates and other mammals," said Kristin Gribble, an associate scientist in the Bay Paul Center at the Marine Biological Laboratory. Research led by postdoctoral scientist Alyssa Liguori, now an assistant professor at SUNY-New Paltz, found that in two genotypes of the same rotifer species, the effects did not increase with every generation and could be rapidly reversed within a single generation.

That pattern suggests the effects are not caused by a gradual buildup of cellular damage or DNA mutations, as many researchers previously thought, but instead by an epigenetic mechanism called histone modification, which switches gene expression on or off without changing the DNA sequence. Gribble's lab is now testing whether these histone changes drive the effects, and is also considering a role for mitochondrial DNA, which is typically inherited from the mother.

In one rotifer strain, offspring of older mothers had a longer lifespan, suggesting a genetic mechanism can sometimes protect against the usual negative effects. Gribble suspects such effects persist across species because natural selection weakens at advanced ages — in rotifers, which do most of their reproducing while young, females have already produced most of their offspring by old age, leaving less evolutionary pressure to keep those effects in check.