UBC Theses and Dissertations
Goa-1 and g protein signalling pathway modulation of the tap withdrawal response Reiss, Aaron
Previous research on Caenorhabditis elegans by Giles (2012) and McEwan (2013) identified the goa-1 gene as a possible regulator of habituation of the tap withdrawal response because mutations in goa-1 caused abnormal habituation across multiple metrics. The original goal of this thesis was to use behavioural and genetic analyses to understand where and how goa-1 functions in habituation of the tap withdrawal response. I planned to use C. elegans with green fluorescent protein (GFP) inserted into wild-type goa-1 as well as tissue-specific degron strains to perform targeted degradation of the GOA-1 protein in subsets of cells. However, when I tested habituation the goa-1::GFP strain found that habituation for the probability of response looked similar to the probability of response habituation for the goa-1 null mutant, yet had a normal, wild-type phenotype for habituation of response duration. I compared our CRISPR goa-1::GFP strain to a second goa-1::GFP strain created by a different single copy insertion technique; the behaviour of this second goa-1::GFP was the same as our goa-1::GFP strain. I tested different mutant goa-1 strains to determine their effects on the habituation phenotypes, however, none of them matched the goa-1::GFP phenotype. Because the goa-1::GFP worms showed normal habituation of response duration I created three GOA-1::GFP degradation strains with pan-neuronal, ciliated neuron, and touch neuron specific degradation. The anatomical results showed that although goa-1::GFP degradation occurred, the behaviour results were inconclusive. Finally, I performed the habituation assay on worms with mutations in genes that were known interactors with goa-1 and found that mutations in dgk-1 led to similar habituation phenotypes as goa-1::GFP worms. The most likely explanation for the goa-1::GFP abnormal habituation phenotype is that the GFP interfered with a signalling pathway that activates the diacylglycerol kinase. These data suggest that the role of goa-1 in habituation of the probability of response is mediated through dgk-1.
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