Expression profiling of the mature C. elegans nervous system by single-cell RNA-Sequencing, bioRxiv, 2019-08-17

AbstractA single neuron and its synapses define the fundamental structural motif of the brain but the underlying gene expression programs that specify individual neuron types are poorly understood. To address this question in a model organism, we have produced a gene expression profile of &gt;90% of the individual neuron classes in the C. elegans nervous system, an ensemble of neurons for which both the anatomy and connectivity are uniquely defined at single cell resolution. We generated single cell transcriptomes for 52,412 neurons that resolve as clusters corresponding to 109 of the canonical 118 neuron classes in the mature hermaphrodite nervous system. Detailed analysis revealed molecular signatures that further subdivide identified classes into specific neuronal subtypes. Notably, neuropeptide-related genes are often differentially expressed between subtypes of the given neuron class which points to distinct functional characteristics. All of these data are publicly available at our website (<jatsext-link xmlnsxlink=httpwww.w3.org1999xlink ext-link-type=uri xlinkhref=httpwww.cengen.org>httpwww.cengen.org<jatsext-link>) and can be interrogated at the web application SCeNGEA (<jatsext-link xmlnsxlink=httpwww.w3.org1999xlink ext-link-type=uri xlinkhref=httpscengen.shinyapps.ioSCeNGEA>httpscengen.shinyapps.ioSCeNGEA<jatsext-link>). We expect that this gene expression catalog will spur the goal of delineating the underlying mechanisms that define the developmental lineage, detailed anatomy, synaptic connectivity and function of each type of C. elegans neuron.

biorxiv neuroscience 100-200-users 2019

Modulation of sensory behavior and food choice by an enteric bacteria-produced neurotransmitter, bioRxiv, 2019-08-15

AbstractAnimals coexist in commensal, pathogenic or mutualistic relationships with complex communities of diverse organisms including microbes1. Some bacteria produce bioactive neurotransmitters which have been proposed to modulate host nervous system activity and behaviors2. However, the mechanistic basis of this microbiota-brain modulation and its physiological relevance is largely unknown. Here we show that in C. elegans, the neuromodulator tyramine (TA) produced by gut-colonizing commensal Providencia bacteria can bypass the requirement for host TA biosynthesis to manipulate a host sensory decision. Bacterially-produced TA is likely converted to octopamine (OA) by the host tyramine beta-hydroxylase enzyme. OA, in turn, targets the OCTR-1 receptor on the ASHASI sensory neurons to modulate an aversive olfactory response. We identify genes required for TA biosynthesis in Providencia, and show that these genes are necessary for modulation of host behavior. We further find that C. elegans colonized by Providencia preferentially select these bacteria in food choice assays, and that this selection bias requires bacterially-produced TA. Our results demonstrate that a neurotransmitter produced by gut microbiota mimics the functions of the cognate host molecule to override host control of a sensory decision, thereby promoting fitness of both host and microbe.

biorxiv neuroscience 0-100-users 2019

 

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