Neural connectivity molecules best identify the heterogeneous clock and dopaminergic cell types in the Drosophila adult brain

Our recent single cell sequencing of most adult Drosophila circadian neurons indicated striking gene expression heterogeneity, about 2-3 cells per clock neuron group. To extend this characterization to other adult fly brain neurons, we used the identical plate-based methods to generate single cell data from a similar subset of dopaminergic neurons. To minimize batch effects and to apply an additional sequencing strategy, we also assayed these two populations together with 10X Chromium. An unsupervised clustering algorithm indicates that dopaminergic neurons are comparably heterogeneous, suggesting that the transcriptomic diversity of adult fly brain neurons parallels its EM connectome. The results here further indicate that connectivity molecules like cell surface molecules best characterize all neuron groups. We suggest that these surprising features are general and make major contributions to neuronal identity and connectivity of the adult central brain as well as underlie the complex behavioral repertoire of Drosophila.