Epigenetics

Franken-ants to help us study epigenetics?

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Who thought twenty years ago we’d be reading science releases like this ? From Jeffrey M. Perkel at The Scientist:

The idea of establishing an ant colony as a model system for epigenetics dates back nearly 12 years to a conversation Reinberg had with Shelley Berger, an epigeneticist at the University of Pennsylvania. Berger had recently returned from a family vacation in Costa Rica, where she spent time watching leaf-cutter ants in action. Ant colonies are highly homogeneous, genetically speaking. Yet their members vary dramatically in shape, size, and behavior. “In some cases the worker and queen are absolutely identical genetically, and yet they have completely different functions,” Berger explains. “The workers give up their reproduction to the queen.” Such phenotypic differences, Berger and Reinberg realized, must come down to epigenetics—variations in gene expression caused by transcription factors, differences in histone modification, noncoding RNA abundance, DNA methylation, and so on.

They recruited ant expert Juergen Liebig of Arizona State University, and the trio settled on a pair of species to study: the carpenter ant Camponotus floridanus and Harpegnathos saltator, aka Jerdon’s jumping ant.

According to Berger, each species offers unique attributes. The carpenter ant has several genetically identical “castes,” including a queen and two worker classes with different body morphologies and behaviors: petite foragers and brawny soldiers. The jumping ant has only one worker caste, but unlike workers of most ant species, they retain the ability to become fertile. If the queen dies or is removed from the colony, some of the workers will fight until a winner emerges, at which point she transforms into a queen—a feature that also makes classical genetics studies feasible, as it allows colonies to be manipulated and propagated.

Most recently, the team showed that epigenetic manipulation of carpenter ants (using histone deacetylase inhibitors and RNA interference) could turn soldiers into foragers (Science, 351:aac6633, 2016). Berger’s team calls these creatures “Frankenstein ants,” she says, as they blend the behavior of one caste with the morphology of the other: “They’re still these big soldier-like ants, but now they’re foraging. We’ve changed their brains, sort of the way Dr. Frankenstein changed the behavior of the monster.” More.

It’s not so much that the selfish gene couldn’t somehow tortuously “explain” all this as that no one would care much about the explanation if epigenetics is simpler.

See also: Epigenetic change: Lamarck, wake up, you’re wanted in the conference room!

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