A gene expression atlas of a juvenile nervous system.
Although the fundamental architecture of metazoan nervous systems is typically generated in the embryo, substantial numbers of neurons are added during post-natal development as existing neurons also expand in size and undergo additional differentiation. To reveal the underlying molecular determinants of post-embryonic neurogenesis and maturation, we have produced gene expression profiles of all neuron types and their progenitors in the first larval stage (L1) of C. elegans. Comparisons of the L1 profile to the embryo and to the later L4 larval stage identified thousands of differentially expressed genes across individual neurons throughout the nervous system. Key neuropeptide signaling networks, for example, are remodeled during larval development. Gene regulatory network analysis revealed potential transcription factors driving the temporal changes in gene expression across the nervous system, including a likely broad role of the heterochronic gene lin-14. We utilized available connectomic data of juvenile animals in combination with our neuron-specific atlas to identify potential molecular determinants of membrane contact and synaptic connectivity. These expression data are available through a user-friendly interface at CeNGEN.org for independent investigations of the maturation, connectivity and function of a developing nervous system. Overall design: Neurons were isolated from L1 stage hermaphrodite Caenorhabditis elegans using Fluroescence-activated cell sorting (FACS) and analyzed using scRNA-seq.