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Construction of the comprehensive olfactory map in C. elegans

Construction of the comprehensive olfactory map in C. elegans
Seoyeong Kim
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Seoyeong Kim; Kyuhyung KimHan Kyoung Choe
Han Kyoung Choe
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Caenorhabdtis elegans, Chemotaxis, AWC neuron, AWA neuron, Volatile chemical
Caenorhabdtis elegans, Chemotaxis, AWC neuron, AWA neuron, Volatile chemical
Animals must recognize and discriminate thousands of chemicals to generate the correct behavioral response. The understanding basic design of a sensory system in simple animals gives the opportunity to elucidate detailed molecular and neural mechanisms underlying sensory responses in higher animals. C. elegans detects a large number of odorants via three neurons pairs including the AWC neurons, and elicit a multitude of olfactory behaviors (Bargmann, 1993, Cell). Due to the established connectome, the olfactory system of C. elegans provides an excellent model system in which to explore the circuit mechanisms underlying olfactory processing at the single cell resolution. Previous genetic and behavioral experiments have identified a set of signaling genes including olfactory receptors, but the knowledge is still limited. Here I investigated molecular and neuronal mechanisms underlying olfactory signaling in C. elegans. I first screened volatile chemicals that were not tested previously and found that worms respond to a distinct set of volatile chemicals including 3,4-hexanedione, formaldehyde, 1-propanol, or 2-propanol. I further identified that the AWC neurons are required for chemotactic responses to these chemicals and certain chemosensory GPCRs which are expressed in AWC mediate chemotactic responses. This study suggests that C. elegans olfactory systems detect a large spectrum of volatile chemicals via the distinct chemosensory neuron-type. |동물들은 일반적으로 수천가지의 화학물질을 감지하고 구분한 뒤 이를 바탕으로 행동 반응을 보인다. 후각은 다양한 종에서 오래 전부터 중요한 감각 기관이었음에도 불구하고 아직까지 odorant와 뉴런, 수용체 사이의 관계가 모두 밝혀져 있지 않다. C. elegans는 고등 생물에 비해 훨씬 간소화 된 신경계를 가지고 있고, 이미 302개의 뉴런이 모두 밝혀져 있다는 점, connectome 또한 밝혀져 있다는 점, 후각에 5% 이상의 유전자들이 코딩 되어 있다는 점 등 신경 실험 모델로서 다양한 장점들을 가지고 있기 때문에 Chemosensation 연구에 유용하게 사용될 수 있다. 이 논문에서는 C. elegans를 통하여 어떤 odorant가 어떤 뉴런들에 의해 감지되고, 어떤 수용체와 결합하는지, 각 odorant에 대한 시그널링을 관찰하였다. 먼저, odorant 스크리닝을 통해 C. elegans가 감지할 수 있는 odorants를 구별하였고, 돌연변이를 이용하여 이 odorant 중 대다수가 AWC 뉴런을 통해 감지되어 호의적인 chemotaxis반응을 보임을 확인하였다. 더 나아가 AWC 뉴런에 발현하는 STR-2와 SRA-13 수용체가 어떤 odorant 감지에 필요한지도 조사하였다. 결과적으로C. elegans가 다양한 휘발성 화합물을 감지할 수 있고, 대부분 호의적인 chemotaxis 반응에 AWC뉴런이 중요하게 작용한다는 것을 밝혔다.
Table Of Contents
Ⅰ. INTRODUCTION 1 1.1 Odorant preference 1 1.2 Olfactory neurons in C. elegans 2 1.3 Olfactory receptors in C. elegans 4 Ⅱ. METHOD 8 2.1 C. elegans stains and genetics 8 2.2 Chemotaxis assays 8 2.3 Statistics analysis 9 Ⅲ. RESULT 12 3.1 Wild-type animals showed attractive chemotactic behavior in newly found odorants 12 3.2 The AWC neurons are required for sensing most of the new odorants 12 3.3 The AWC ON or OFF neurons are required for distinct odorants 17 3.4 STR-2 and SRA-13 GPCRs are required for chemotactic responses to particular odorants 17 Ⅳ. DISCUSSION 21 Ⅴ. REFERENCES 24 요약문 29
Brain and Cognitive Sciences
Related Researcher
  • Author Choe, Han Kyoung Laboratory of Animal Behavior and Circadian rhythm
  • Research Interests Modulation of neural circuit; Circadian regulation of behavior and perception; Neurotechnology
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