Commit 5d56d2f0 authored by mk11g11's avatar mk11g11
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corrections

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......@@ -16,3 +16,4 @@ geometry: "left=4cm, right=1.5cm, top=1.5cm, bottom=1.5cm" # Change to margins r
library(tidyverse)
library(kableExtra)
```
......@@ -7,22 +7,29 @@ AChBP - Acetylcholine Binding Protein \\
bgtx - bungarotoxin \\
Bovine Serum Albumin (BSA) \\
e. coli
ER- endoplasmic reticulum
polyvinylidene difluoride (PVDF)
C. elegans
GLIC - \textit{Gloebacter} ligand gated ion channels \\
glutamine-gated chloride (GluCl)
Green Fluorescent Protein (GFP) \\
Hermaphrodite Specific Neurons (HSNs) \\
BWM - Body Wall Muscle \\
Ch - choline \\
ChAt - Choline acetyltransferase \\
dimethyl sulfoxide (DMSO) \\
ECD - extracellular domain \\
E/R ratio
ELIC - \textit{Erwinia} ligand gated ion channels
ELIC - \textit{Erwinia} ligand gated ion channels\\
GABA - Gamma aminobutyric acid \\
GPCR - G protein coupled receptor \\
nAChR : nicotinic acetylcholine receptor \\
NGM - nematode growth medium \\
NMJ - Neuromuscular junction\\
neurosecretory motor neurons (NSM\\
RIC-3 - Resistant to Inhibitors of Cholinesterase-3 \\
TM - transmembrane
SDS-PAGE - sodium dodecyl sulfate polyacrylamide gel electrophoresi
TM - transmembrane \\
RIC-3 - (resistant to inhibitors of cholinesterase-3\\
VAChT - Vesicular acetylcholine transferase \\
MBP - Maltose Binding Protein
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\addcontentsline{toc}{chapter}{Abstract}
\chapter*{Abstract}
An ability of insecticides to selectively target pests without affecting non-target species is key determinant of success of compounds used in agriculture. Neonicotinoids which encompass seven different types of chemical representing three distinct chemical classes, namely the cyanoamidines, nitroguanidines and nitromethylenes, are a major class of insecticides. They effectively control a wide range of insect pests and have low toxicity against mammals, however they can also negatively impact on non-target species of bees, threatening food safety. Neonicotinoids act by targeting insect nicotinic acetylcholine receortors (nAChRs), which are major excitatory receptors in the insect central nervous system. Difficulties in heterologous expression of these proteins hinders their pharmacological characterisation and identification of the molecular determinants of neonicotinoid-toxicity. This thesis describes efforts into developing \textit{Caenorhabditis elegans (C. elegans)} as a platform in which the mode of action and selective toxicity of neonicotinoid-insecticides can be studied.
An ability of insecticides to selectively target pests without affecting non-target species is a key determinant of success of compounds used in agriculture. Neonicotinoids which encompass seven different types of chemical representing three distinct chemical classes, namely the cyanoamidines, nitroguanidines and nitromethylenes, are a major class of insecticides. They effectively control a wide range of insect pests and have low toxicity against mammals, however they can also negatively impact on non-target species of bees, threatening food safety. Neonicotinoids act by targeting insect nicotinic acetylcholine receortors (nAChRs), which are major excitatory receptors in the insect central nervous system. Difficulties in heterologous expression of these proteins hinders their pharmacological characterisation and identification of the molecular determinants of neonicotinoid-toxicity. This thesis describes efforts into developing \textit{Caenorhabditis elegans (C. elegans)} as a platform in which the mode of action and selective toxicity of neonicotinoid-insecticides can be studied.
We determined the effects of neonicotinoids on \textit{C. elegans} behaviours governed by the cholinergic neurotransmission. The cyanoamidine represented by clothianidin, the nitroguanidine represented by thiacloprid and the nitromethylene represented by nitenpyram showed low efficacy on locomotion, pharyngeal pumping, egg-laying and egg-hatching of young adult wild-type \textit{C. elegans}. Exposure of mutant worm with enhanced cuticular permeability showed increased susceptibility of worms to all three neonicotinoids tested, suggesting an adult cuticle limits drug access. The role of the cuticle in neonicotinoids susceptibility was investigated in \textit{C. elegans} cut-head preparation, in which the cuticle is removed and the effects of compounds on pharyngeal pumping are scored. Out of the three neonicotinoids applied, clothianidin showed the greatest efficacy. It stimulated pharyngeal pumping at $\geq$ 75 $\mu$M (18.75 ppm). Generally, the concentrations effective against the function of the pharynx are an order or magnitude lower than the residual, average concentration of neonicotinoids in the soil, suggesting \textit{C. elegans} is not impacted in the field, and at least several fold lower than lethal doses in insect-pests. The difference in neonicotinoid-susceptibility between adult \textit{C. elegans} and insects precludes the use of \textit{C. elegans} pharynx as a platform for the mode of action studies, but highlights its potential as a suitable background for the heterologous expression of insect nAChRs.
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......@@ -2,7 +2,7 @@
\chapter*{Acknowledgements}
Throughout the process of PhD study, research and writing this thesis, I have received a great deal of support and help.
I would like to thank my supervisors: Dr Declan Doyle, Prof Vincent OConnor and Prof Lindy Holden-Dye, whose expertise, knowledge, enthusiasm and motivation was invaluable. Without your guidance this PhD would have been unachievable.
I would like to thank my supervisors: Dr Declan Doyle, Prof Vincent O'Connor and Prof Lindy Holden-Dye, whose expertise, knowledge, enthusiasm and motivation was invaluable. Without your guidance this PhD would have been unachievable.
I would like to acknowledge The Gerard Kerkut Charitable Trust for providing funding for this PhD project.
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......@@ -5,4 +5,4 @@ Part of this thesis has been published in the following papers:
Kudelska, M. M., L. Holden-Dye, V. O'Connor, and D. A. Doyle. 2017. Concentration-Dependent Effects of Acute and Chronic Neonicotinoid Exposure on the Behaviour and Development of the Nematode \textit{Caenorhabditis elegans}. Journal Article. Pest Manag Sci 73 (7): 1345–51. https://doi.org/10.1002/ps.4564.
Kudelska, M. M., A. Lewis, C. T. Ng, D. A. Doyle, L. Holden-Dye, V. M. O'Connor, and R. J. Walker. 2018. Investigation of Feeding Behaviour in \textit{c. elegans} Reveals Distinct Pharmacological and Antibacterial Effects of Nicotine. Invertebrate Neuroscience : IN 18 (4): 14. https://doi.org/10.1007/s10158-018-0219-1.
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Kudelska, M. M., A. Lewis, C. T. Ng, D. A. Doyle, L. Holden-Dye, V. M. O'Connor, and R. J. Walker. 2018. Investigation of Feeding Behaviour in \textit{C. elegans} Reveals Distinct Pharmacological and Antibacterial Effects of Nicotine. Invert Neurosci 18 (4): 14. https://doi.org/10.1007/s10158-018-0219-1.
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