The Mechanism Of Sensory Information Coding In Caenorhabditis Elegans

Animals rely heavily on the nervous system to detect physical and chemical sensation.This ability is conserved across species which enables animals to survive in harsh and variable environmental conditions.Caenorhabditis elegans(C.elegans)are nematodes generally living in a relatively complex ecology,with flexible temperatures,numerous physical obstacles,and diverse chemical substances.There are also countless favorable and harmful bacteria,fungi,and other organisms in their habitat.As such,C.elegans need to detect and differentiate multitudinous stimuli via distinct sensory signals and pathways in the immediate surroundings.In this study,we use C.elegans as model organisms and combine multidisciplinary technologies to explore physical and chemical sensation along its molecular mechanisms.In the first part,we found that the OLL sensory neurons of C.elegans can respond to both touch and cold stimulation.Mechanical stimulation can induce the autonomous robust calcium transient and the rapidly-adapting mechanoreceptor currents in OLL sensory neurons.Based on a series on experimentations,we uncovered a novel amiloride-insensitive sodium conduction channel that may mediate the mechanotransduction of OLL neurons where known mechano-gated channels do not participate in the mechanotransduction.Further,OLL neurons also mediate cold but not warm sensation while the identified cold receptors,TRPA-1 and GLR-3 are not responsible for the cold sensation of OLL neurons.Hence,we revealed the polymodal functionalities of OLL neurons in mechanosensation and cold sensation.In the second part,we explored the molecular mechanism of mechanosensation in C.elegans male-specific neurons.In this study,we found that the pheromone-sensitive CEM neurons also mediate mechanosensation in a cell-autonomous manner.Mechanical stimulation evoked robust calcium transients and rapid mechanoreceptor currents in CEM neurons.Moreover,chloride conductance channels mediate the mechanotransduction of CEM neurons and exogenous expression and activation of chloride channels can effectively stimulate CEM neurons.We observed that under physiological conditions,CEM neurons are in high chloride ion concentration.In terms of behavior,CEM neurons participate in the male nose touch avoidance response.Therefore,we suggest the polymodal functionalities of CEM neurons in both chemoreception and mechanosensation.Critically,our results show that mechanical stimulation can activate an excitatory chloride channel.Thus,our work broadens the repertoire of mechano-gated ion channels.In the third part,we revealed the real-time function of C.elegans glia in chemoreception.We found that C.elegans AMsh glia play a role in olfactory perception and adaptation.AMsh glia cell-autonomously sense the aversive odorant,IAA,by its specific olfactory receptor — the G protein-coupled receptor SRH-79.As a polymodal sensory neuron in C.elegans,ASH neurons are known to detect various repulsive odorants and mediate avoidance responses.Optogenetic activation of AMsh glia effectively reduced the excitability of ASH neurons,while at behavioral level,the worms showed latency in the avoidance response to repulsive odorants.Consequently,AMsh glia decreased the sensitivity of ASH neurons to odor and promoted olfactory adaptation.Here,we propose novel bona fide olfactory receptor cells and a glia-neuron multicellular olfactory adaptation model.We also unveiled the real-time function of glia in olfactory transduction which may provide novel perspectives of glia in mammalian sensory transduction.Sensation is one of the most basic functions in the nervous system of humans and animals.They perceive meticulously the surrounding and respond appropriately to favorable or harmful environments,thereby maintaining homeostasis.Sensory information coding is the conversion of external environmental stimuli into nerve impulses where the central system obtains a subjective sense of the nature and intensity of stimulation according to these encoded signals and then generates appropriate behavioral output.Mechanosensation,temperature sensation,and olfactory sensation are essential to the survival of animals and play a crucial part in perceiving the surroundings in much greater details.This article will be an excellent enlightenment in uncovering the mechanism of sensory information coding.