Researchers from the University of Pennsylvania have discovered that the social behavior of carpenter ants can be reprogrammed via epigenetic, rather than genetic factors.
Epigenetics is the study of gene expression changes without the involvement of DNA sequence alterations. Many distinct animal traits such as size, behavior and aging have been associated with epigenetics.
Eusocial insects such as ants settle together within colonies of species that have a similar genetic makeup. The animals are categorized into castes according to its behavior and morphological characteristics. Through this division, the species are assigned with specific tasks and the entire groups' social adaptation becomes organized.
The caste system is highly established, but for one type of insect called carpenter ants (Camponotus floridanus), such system may possibly be defied. This is because of the change in assigned behaviors of each division that has been altered by epigenetic substances known as acetyl groups.
Acetyl groups are connected to histone protein complexes, where DNA strands are wrapped in the nucleus of a cell.
Histone modification is a technique used to identify the properties of different tissues inside individual species. With this, the team wondered if histone alterations may induce differences in social behavior between the two types of foraging ants: the stronger, bigger-bodied majors and the smaller but brainier minors.
For the experiment, the researchers fed minors with substances that inhibit cells from removing acetyl groups from histones. Such move improved the species' ability to look for and forage food. Histone acetylation also increased the neuronal activity of near genes.
Consequently, when the researchers prevented the addition of acetyl groups, the species decreased its foraging activity.
While the intervention significantly resulted in positive effects for minors, the impacts on majors were not that notable. Although there was an increase in foraging, the change was not that significant.
When the substances were injected directly into the brains of the youngest majors, however, foraging increased in levels similar to that of the productive minors.
The researchers also discovered that the epigenetic inhibitors were adequate enough to cause foraging efficiency for up to 50 days. The finding suggests that young ant brains may still be susceptible to environmental manipulations, such as histone-altering inhibitors.
"Because of the remarkable window we have uncovered, ants also provide an extraordinary opportunity to explore and understand the epigenetic processes that come into play to establish behavioral patterns at a young age," said lead author Shelley Berger.
The discovery may pave the way for experts to understand the behaviors of humans, especially in the face of increasingly prevalent behavioral disorders.
Another implication is the involvement of an epigenetic enzyme writer called CBP, which changes chromatin by acetyl groups to histones. In the past, CBP has already been recognized as an important factor in the learning and memory abilities of mice. In some disorders such as Rubinstein-Taybi syndrome, CBP was found to be mutated.
"From mammalian studies, it's clear this is an important protein involved in learning and memory," Berger said.
Now, experts are looking at the possible role of CBP in the social behaviors of vertebrate species.
The study was published in the journal Science on Jan. 1, 2016.
