| The C.elegans has become an ideal model organism by researchers in nervous system functions and neural circuits. There are several reasons for its wide spread use: the simple anatomical structure, short life circle, high breed competency and the whole genome sequenced yet. We use specific promoters through infusion technique and second spliced leader (SL2) system to express different fluorescent proteins to determine the specific location of C.elegans neurons and glia, whereas using confocal laser scanning technique to confirm the expression driven by promoters. After the interested neurons or glial cells are specific marked, we use optogenetics protein Channelrhodopsin-2(ChR2) and GCaMP proteins in further study of the nervous system and neural circuits. We cloned the specific promoters to locate olfactory neurons AWA, AWB, AWC, ASH, ADL and two kinds of glia Amphid sheath glia and Cephalic sheath glia. Via chemotaxis assay we find C.elegans have a preference on diverse concentrations of IAA from attractive to repulsive. Furthermore, we have analysed the olfactory neurons AWA AWB AWC response to different concentrations of IAA by electrophysiology technology. In vivo Calcium imaging and in vivo patch clamp show that polymodal ASH sensory neurons only respond to high concentration (10-2IAA) rather than low concentration (10-4IAA), which is mediated by TRPV channel OSM-9. All above indicate that C.elegans concentration-dependent olfactory preference is mediated by several sensory neurons through different response modes. In addition, in order to study the development mechanism of nematode glial cells and its function on neural system, we use EMS forward genetics screening and find the key determinants vab-3, which is located in paired domain. The preliminary mechanism is proteins translation has been terminated by a stop codon, which causes a severe defect in dendrite migration and axon guidance. |
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