Florida carpenter ants (Camponotus floridanus) develop specialized jobs early in adulthood. “Major” worker ants are large soldier ants that help protect the colony, while “minor” worker ants are smaller and forage for food. Researchers have identified an epigenetic pathway that can be altered to make majors show foraging behaviors like minor ants, according to a paper published in Molecular Cell yesterday (November 12).
A team led by Shelley Berger, an epigeneticist at the University of Pennsylvania Perelman School of Medicine, injected the brains of major ants with the chemical trichostatin A at either 0, 5, or 10 days after the insects reached adulthood. This caused hundreds of genes to be differentially expressed. One important upregulated gene was RCOR1, which codes for a protein called CoREST that was found to be responsible for the altered ant behavior. It prevents the degradation of juvenile hormone, normally found in high levels in minors but low levels in majors. Ants injected at 10 days after becoming adults did not show different gene expression or changes in behavior, suggesting that behavioral plasticity has a narrow window.
“Given how highly related workers of different castes are to one another, we’ve always suspected that the epigenome plays a big role in their huge behavioral differences,” said first author Karl Glastad, a postdoc in the Berger lab, in a news release. “However, this is the first study where the actual mechanism has been identified, from epigenome, through hormonal signaling, and finally to behavior.”
K.M. Glastad et al., “Epigenetic regulator CoREST controls social behavior in ants,” Mol Cell, doi:10.1016/j.molcel.2019.10.012, 2019.
Emily Makowski is an intern at The Scientist. Email her at email@example.com.