Experiences during early development can influence neuronal functions and modu-late adult behaviors. However, the molecular mechanisms underlying the long-term be-havioral effects of these early experiences are not fully understood. The C. elegans ascr#3 pheromone triggers avoidance behavior in adult hermaphrodites.
Here, I show that hermaphrodites that are briefly exposed to ascr#3 immediately af-ter birth exhibit increased ascr#3-specific avoidance as adults indicating that ascr#3-experienced animals form a long lasting memory or imprint of this early ascr#3 exposure. ascr#3 imprinting is mediated by increased synaptic activity between the ascr#3-sensing ADL neurons and their post-synaptic SMB motor neuron partners via increased expression of the odr-2 GPI-linked signaling and avr-14 glutamate-gated chloride channel genes in the SMB neurons.
My study suggests that the memory for early ascr#3 experience is imprinted via al-teration of a single synaptic connection, that in turn shapes experience-dependent plastici-ty in adult ascr#3 responses. ⓒ 2017 DGIST
Table Of Contents
Ⅰ. Introduction 1--
1.1 Neuroconnectome 1--
1.2 Synaptic plasticity 1--
1.3 Studying of C. elegans as a model system 2--
1.4 C. elegans pheromones 3--
1.5 Early pheromone-experienced study of C. elegans 4--
II. Experimental Method & Materials 5--
2.1 Experimental Model and Subject Details 5--
2.2 Method Details 5--
2.2.1 Generation of C. elegans transgenic lines 5--
2.2.2 Pheromone imprinting 6--
2.2.3 Post-dauer assay 7--
2.2.4 Behavioral assay 7--
2.2.5 In vivo calcium imaging 8--
2.2.6 Levamizole treatment 8--
2.2.7 Heat shock treatment 9--
2.3 Quantification and Statistical Analysis 9--
2.3.1 Representative images 9--
2.3.2 GFP quantification 9--
2.3.3 Statistical tests 10--
III. Result 11--
3.1 Adult C. elegans transiently exposed to ascr#3 during larval stages ex-hibits increased acsr#3 pheromone avoidance 11--
3.1.1 Pheromone imprinting assay of naive and pre-exposed worms 11--
3.1.2 Optimal ascr#3 concentration of pre-exposure effect 13--
3.1.3 Early ascr#3 experience of males 14--
3.2 The memory for ascr#3 is acquired during the L1 larval stage 14--
3.2.1 ascr#3 imprinting is L1 specific 14--
3.2.2 The critical time for imprinting of L1 stage 15--
3.2.3 ascr#3 imprinting is pheromone specific 16--
4.1 odr-2 Acts in the SMB neurons to increase ascr#3 avoidance in ascr#3-imprinted animals 20--
4.1.1 Candidate gene search 20--
4.1.2 odr-2 recue study 22--
4.1.3 SMB sensory/inter/motor neurons 24--
4.1.4 Association of SMB and Imprining 25--
4.2 ascr#3-induced responses in the ADL chemosensory neurons are unal-tered in ascr#3 imprinted worms 25--