Gene expression dissection of the circadian neuronal circuit of Drosophila identifies novel circadian genes

Gene expression profiling of distinct members of a neuronal circuit has the potential to identify candidate molecules and mechanisms that underlie the formation, organization and function of the circuit. To this end, we report here the application of a novel method to characterize RNAs from small numbers of specific Drosophila brain neurons, which belong to the circadian circuit. We identified three different sets of mRNAs enriched in different subclasses of clock neurons: one is enriched in all clock neurons, a second is enriched in PDF-positive clock neurons and a third is enriched in PDF-negative clock neurons. Moreover, we characterized 2 novel genes, Fer2 and dnocturnin, one from each subgroup, which highlight subgroup-specific features and play important roles in circadian rhythms. The methodology is a powerful tool not only to dissect the cellular and molecular basis of circadian rhythms but also to molecularly characterize other Drosophila neuronal circuits.

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