Biology

Dr. Abhishek Bhattacharya
Department of Biological Sciences, Columbia University, New York, USA

Abstract:

Understanding the synaptic wiring of an entire nervous system - its ‘connectome’ - is an essential first step to elucidate how nervous system processes information and generates behavior. Connectomes have two components – the wiring diagram of all chemical synapses and that of all electrical synapses. My work focuses particularly on the electrical synaptic wiring, which has generally remained the stepchild of synapse biology, particularly in regards to its development and plasticity. My work is a first ever attempt to understand the molecular logic of electrical synaptic specificity and functional diversity of an entire nervous system, which have been proposed to be defined by the neuron-specific complement of electrical synapse constituents. I systematically defined the molecular composition of the electrical connectome of the nematode C. elegans through a genome- and nervous-system-wide analysis of the expression patterns of the invertebrate electrical synapse constituents, the innexins. I observed highly complex combinatorial expression patterns throughout the nervous system. This work provides insights into the yet unknown molecular determinants of the electrical synaptic specificity and functional diversity, and provides novel entry points to decipher them. I will also present my work showing that these innexin expression patterns change in a strikingly neuron-type-specific manner throughout the nervous system when animals enter a diapause arrest stage under harsh environmental conditions. I found an intersectional gene regulatory mechanism that mediates dynamic innexin expression plasticity in a neuron-type- and environment-specific manner, which ultimately leads to circuit plasticity. By analyzing individual synapses, I demonstrated that these stage-specific electrical synapse remodeling are responsible for particular aspects of the stage-specific behavioral alteration.