Optimisation and application of the GH3.TRE.Luc Reporter Gene Bioassay to assess thyroid activity in drinking and source water

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dc.contributor.advisor Aneck-Hahn, Natalie H. en
dc.contributor.coadvisor De Jager, Christiaan en
dc.contributor.postgraduate Simba, Hannah en
dc.date.accessioned 2017-08-15T12:35:30Z
dc.date.available 2017-08-15T12:35:30Z
dc.date.created 2017-05-05 en
dc.date.issued 2017 en
dc.description Dissertation (MSc)--University of Pretoria, 2017. en
dc.description.abstract The endocrine system is vulnerable to a range of chemicals in the environment. Endocrine disrupting chemicals (EDCs) are exogenous agents that can induce responses on the endocrine system because of their hormone-like activity and toxicity. Specific to this study are thyroid disrupting chemicals (TDCs), these are EDCs that specifically disrupt the thyroid hormone signalling pathway, and this may result in adverse health effects. Thyroid hormones play a crucial part in metabolism, growth, maintenance of brain function and fertility; hence disruption of the thyroid signalling axis implicates human health. We are exposed to TDCs regularly, and studies have shown an association between TDC exposure and neurobehavioural disorders, reproductive abnormalities and obesity. There is a lack of data associated to thyroid hormone receptor activity in surface and drinking water. Hence, the potential human health risks posed by thyroid disruption may therefore be underestimated. The aim of the study was to optimise and validate the GH3.TRE.Luc reporter gene bioassay that can measure thyroid hormone receptor mediated activity and cytotoxicity in drinking and source water, with relevance to water monitoring. The GH3.TRE.Luc reporter gene bioassay was established, optimized and validated to detect thyroid hormone receptor activity. The luciferace assay was used to test for metabolic activity and the resazurine cell proliferation assay was used to assess cell viability. The assay was applied to compounds with agonistic and antagonistic properties; triidothyronine (T3), thyroxine (T4), triac, tetrac, amiodarone, sodium arsenite, pentachlorophenol (PCP), ethylene thiourea, 2,2,4,4-tetrahydroxybenzophenone (THBP) and methimazole. It was also applied to environmental and drinking water samples from the Global Water Research Coalition (GWRC). Finally, the assay was applied to 48 water samples from a water treatment plant in South Africa, collected over a period of 12 months. Every month, four samples were collected. Two samples were source water samples, with one going into the treatment plant and coming out as 2 distribution pipelines (drinking water). For optimisation and validation, the dose response curves obtained for T3, T4, tetrac and triac (agonists) were comparable to literature. Antagonistic behaviour was seen in sodium arsenite, amiodarone, PCP and methimazole. Spiked water samples from the GWRC showed thyroid hormone receptor activity. Sixteen of the 48 water samples collected from the water treatment plant were positive for thyroid hormone disruptor activity. Highest activity was seen in the winter season, accounting for seasonal variations. High TDCs activity reported in the source water may be due to activities occurring near the dam. The water treatment plant seemed effective for only one of the distribution pipelines, and not the other. This study confirms that GH3.TRE.Luc Reporter Gene Bioassay is a sensitive and effective tool to identify and quantify TDC activity in pure chemicals and in complex environmental mixtures present in water. Further monitoring of water sources for TDCs is recommended to ensure water quality and safety. en
dc.description.availability Unrestricted en
dc.description.degree MSc en
dc.description.department School of Health Systems and Public Health (SHSPH) en
dc.identifier.citation Simba, H 2017, Optimisation and application of the GH3.TRE.Luc Reporter Gene Bioassay to assess thyroid activity in drinking and source water, MSc Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/61668> en
dc.identifier.other A2017 en
dc.identifier.uri http://hdl.handle.net/2263/61668
dc.language.iso en en
dc.publisher University of Pretoria en
dc.rights © 2017 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. en
dc.subject UCTD en
dc.subject Thyroid hormones en
dc.subject Thyroid disrupting chemicals en
dc.subject Endocrine disrupting chemicals en
dc.subject Thyroid equivalents en
dc.title Optimisation and application of the GH3.TRE.Luc Reporter Gene Bioassay to assess thyroid activity in drinking and source water en_ZA
dc.type Dissertation en


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