Social insects are an ideal system to study the role of gene regulation in brain development and function because individuals from different castes (workers and queens) display dramatic different behaviors despite sharing the same genome. 

We have been developing the ant Harpegnathos saltator as a model organism because of its unique phenotypic plasticity. In Harpegnathos ants, adult workers can become queens via a caste transition that results in germline activation, lifespan extension, and major changes in behavior. This transition can be induced and reversed and offers a unique experimental paradigm to study the molecular regulation of behavioral and neuroanatomical plasticity. In the past ten years, we have sequenced the Harpegnathos genome, determined that all major epigenetic pathways are conserved and active in this organism, and have established various manipulation techniques, including gene knockdowns and genome editing.

Using various functional genomics approaches, we discovered that as brains of workers transition to queen they display a remarkable degree of molecular and cellular plasticity. At a molecular level, hundreds of coding and noncoding genes are differentially regulated in the brain, suggesting that transcriptional reprogramming contributes to the observed changes in behavior. Among these, we discovered a transcription factor that participates in caste selection by repressing genes from the opposite caste in response to socially-regulated hormones. At a cellular level, we found that neuroprotective glia cells expand as workers become queens, perhaps contributing to their extended lifespan, and that a population of neurons in the mushroom body also increases in relative frequency after the transition.

Our results reveal that socially regulated changes in gene expression induce brain remodeling and behavioral reprogramming in Harpegnathos.

Those who wish to meet the speaker should contact Jin Zhang, Zucker Lab

The Columbia Neuroscience Seminar series is a collaborative effort of Columbia's Zuckerman Institute, the Department of Neuroscience, the Doctoral Program in Neurobiology and Behavior and the Columbia Translational Neuroscience Initiative, and with support from the Kavli Institute for Brain Science.