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Title: Life-cycle toxicity testing in Caenorhabditis elegans : comparative effects on traits and their mechanistic basis
Author: Wren, Jodie Frances
ISNI:       0000 0004 2749 3490
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2006
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A major aim of ecotoxicology is to discover how toxicants impact populations. Often lethality is used as an endpoint in toxicity tests however this in isolation is inadequate to predict consequences for populations. The combination of life cycle toxicity testing and demographic modelling offers an opportunity to provide a solution to this problem, whilst the use of transcriptomic profiling offers the chance to understand how changes in life history are mediated at the molecular level. The nematode Caenorhabditis elegans was utilised to elucidate the effects of environmental toxicants on the life history of individuals, population growth rate, energy utilisation, and gene expression. Toxicity of four common pollutants (cadmium, fluoranthene, atrazine and aldicarb) was assessed in full life-cycle toxicity tests. The impact of each chemical on life history parameters including reproductive output/ period, time to maturity, growth and lifespan, was determined. These experiments revealed complex dose dependent responses indicating the most sensitive trait to be reproductive output. The influence of temperature and strain was investigated on cadmium toxicity indicated an increase in overall sensitivity at higher temperature and strain specific response profiles. Integration of life history data into a demographic model provided a solution to translating effects on individuals into meaningful population responses. Decreases in juvenile survival and reproduction were identified as the traits which caused the largest impacts on population growth rate. Life-cycle toxicity data was also integrated into a process-based model (DEBtox) to assess the effects of the toxicants on energy utilisation by the organisms. Finally, the mechanistic basis of observed life-history responses for the toxicant aldicarb was examined using transcriptomic profiling to identify single genes and biological and energetic pathways responsive to toxicant stress. Analysis of the molecular responses revealed novel mechanisms of toxicity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available