Science Daily reveals how one species of ant takes on their own brains and programs their social roles – doing the job we thought DNA did:
In Florida carpenter ant colonies, distinct worker castes called minors and majors exhibit pronounced differences in social behavior throughout their lives. In a new study published today in Science, a multi-institution team anchored at University of Pennsylvania found that these caste-specific behaviors are not set in stone. Rather, this pioneering study shows that social behavior can be reprogrammed, indicating that an individual’s epigenetic, not genetic, makeup determines behavior in ant colonies.
Epigenetics is the study of stable, or persistent, changes in gene expression that occur without changes in DNA sequence.
In a previous study, the authors created the first genome-wide epigenetic maps in ants. This revealed that epigenetic regulation is key to distinguishing majors as the “brawny” soldiers of carpenter ant colonies, compared to minors, their smaller, “brainier” sisters. Major ants have large heads and powerful mandibles that help to defeat enemies and process and transport large food items. Minor ants are much smaller, outnumber majors two to one, and assume the important responsibility of searching for food and recruiting other ants to help with the harvest.
In the new findings, an interdisciplinary research team led by senior author Shelley Berger, PhD, from the Perelman School of Medicine at the University of Pennsylvania, in collaboration with teams led by Juergen Liebig from Arizona State University and Danny Reinberg from New York University, found that caste-specific foraging behavior can be directly altered, by changing the balance of epigenetic chemicals called acetyl groups attached to histone protein complexes, around which DNA strands are wrapped in a cell nucleus.
So, by messing with these chemicals – histones – the group could reprogram how the same DNA was expressed in different individuals. Both had the same genes, but one set would get brainier, and the other, brawnier, depending on when and how the histones were inhibited.
The results, though, can go even deeper than building a smarter ant….
In contrast to the dramatic boost in foraging seen in minors, feeding mature major workers these inhibitors caused little to no increase in foraging. However, the team found that directly injecting these epigenetic inhibitors into the brains of very young majors immediately increased foraging, reaching levels normally only observed in minors. Additionally, a single treatment with these inhibitors was sufficient to induce and sustain minor-like foraging in the majors for up to 50 days. These results suggest that there is an “epigenetic window of vulnerability” in young ant brains, which confers increased susceptibility to environmental manipulations, such as with histone-modifying inhibitors.
Berger observes that all of the genes known to be major epigenetic regulators in mammals are also present in ants, which makes ants “a fantastic model for studying principles of epigenetic modulation of behavior and even longevity, because queens have a much longer lifespan compared to the major and minor workers….”
We called these guys “bull ants” when I was growing up in Florida, and had no idea how complicated they were.