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Both inositol 1,4,5-trisphosphate (IP3) mediated signalling and RNA interference are widespread processes with fundamental roles in animal cell function. In the nematode C. elegans these two pathways have been shown to intersect such that IP3 signalling mutants display an altered exogenous RNAi response. IP3 is a key second messenger in the transduction of intracellular signals. Produced by the hydrolysis of membrane phospholipid PIP2 by phospholipase C (PLC), IP3 triggers Ca2+ release from internal stores by binding to the IP3 receptor, a ligand gated calcium channel in the ER, thus triggering downstream calcium signalling pathways. It has been previously shown that loss of function in the IP3 receptor (ITR-1) or in PLCβ (EGL-8) results in an enhanced response to exogenous dsRNA, with a more robust silencing response than that seen in WT worms. Conversely the potentiation of IP3 signalling by the loss of function IPP-5, a phosphatase which catalyses the hydrolysis of IP3, results in resistance to RNAi. In order to better understand the context of the IP3 signalling events which are regulating the RNAi response I sought to identify the upstream activator of EGL-8 in this mechanism. EGL-8 is canonically activated by Gαq homologue ELG-30. However, by screening the RNAi responses of Gα signalling mutants using a range of assays, EGL-30 was ruled out as an activator of EGL-8 in the pathway regulating RNAi, since EGL-30 loss of function does not result in an enhanced RNAi response. The Gαo/i homologue, GOA-1, was identified as the most likely activator of EGL-8 due to the strongly enhanced RNAi response in goa-1 loss of function mutants in a number of assays. Other Gα subunits and known regulators of GOA-1 and EGL-30 signalling were also analysed. The RNAi response is a multistep process in which the exogenous RNAi pathway must compete with the closely related and interlinked endogenous small RNA pathways for resources. With the aim of better understanding how changes in IP3 signalling might be influencing the RNAi response, small RNA sequencing was performed to look for evidence of change in the endogenous small RNA pathways of itr-1 mutants, and followed up with qPCR. However, no substantial changes to the endogenous small RNA pathways were found. Downstream of the production of primary siRNAs from exogenous dsRNA, separate argonautes mediate cytoplasmic and nuclear RNAi responses. I utilised an established assay to test for effects of IP3 signalling on nuclear RNAi. The results suggest no specific alterations to the nuclear RNAi pathway in these mutants.

The work presented in this thesis uses structural priming to investigate pragmatic enrichment. Chapter 2 looks at the role the alternative plays in the derivation of scalar implicatures. We investigate whether the salience of the alternative is sufficient for the derivation of scalar implicatures or whether an additional usage mechanism is required. Chapter 3 focuses on the derivation of one particular category of implicature known as ad hoc implicatures. Ad hoc implicatures are different from traditional scalar implicatures in that they do not have a predefined scale from which to draw alternatives. We test whether specific alternatives are used in the derivation of ad hoc implicatures or whether a general anything else alternative is used. Chapter 4 investigates interlocutor alignment in the production of implicatures. Since implicature comprehension can be primed we extend this by investigating implicature production. The findings of the work presented here demonstrate that structural priming can be extended beyond its traditional application to syntax and semantics and can be used to provide insight into pragmatic enrichments.