Single-cell transcriptomics in the Drosophila midbrain: linking molecules to neuronal function

Biosciences Special Seminar

Speaker: Dr Vincent Croset, University of Oxford

Host: Dr Carolina Rezaval

Molecules are essential for neurons to function, neural circuits to operate and for brains to instruct behaviour. Single-cell transcriptomics provides the unique power to assess the diversity of cell types in the nervous system. Near complete representation can be easily achieved when combined with the relatively small brain of the fruit fly Drosophila. I will present a dataset of tens of thousands of single cells from the fly midbrain generated with Drop-Seq and 10X Genomics’ Chromium. Cluster-based analysis assigned transcriptional profiles to neurons comprising several recognised brain areas and in some cases hints towards greater molecular heterogeneity than previously envisaged. Beyond cell-type clustering, neurons can be classified according to neurotransmitter, neuromodulator and/or neuropeptide expression. Most cells express two or more transmitters suggesting possible new rules for co-transmission. Some neuropeptides are preferentially co-expressed with a particular fast-acting neurotransmitter. In contrast, neuropeptide expression in monoaminergic neurons appears more diverse with subsets of a given class of monoamine releasing cells, producing different neuropeptides. The next step in these analyses is to test the functional significance of cell-specific genes identified in this ‘static’ brain atlas and to perform more ‘dynamic’ single-cell analyses across behavioural states. I will present my latest data investigating cell-specific modulation of gene expression in the context of water deprivation and learning.