Show simple item record

dc.contributor.authorGreen, Jon Marc
dc.date.accessioned2017-04-18T11:14:14Z
dc.date.issued2016-09-20
dc.description.abstractOestrogenic chemicals have become increasingly associated with health effects in wildlife populations and humans. Transgenic animal models have been developed to understand the mechanisms by which these oestrogenic chemicals alter hormonal signalling pathways and how these alterations can lead to chronic health effects. The use of highly informative transgenic animal models will also result in better use and potential reduction of intact animals used in animal testing in line with the principles of the 3Rs. In this thesis work, two novel oestrogen responsive transgenic zebrafish models have been generated to investigate the effects of oestrogenic chemicals, identify their tissue targets and better understand the temporal dynamics of these responses. Both models express the pigment-free ‘Casper’ (a mutant line lacking skin pigment) phenotype, which facilitate identification of responding target tissues in the whole fish in all fish life stages (embryos to adults). The oestrogen response element green fluorescent (ERE-GFP)-Casper model was generated by crossing an established ERE-GFP line with the skin pigment free Casper line. The model generated is highly sensitive to oestrogenic chemicals, detecting responses to environmentally relevant concentrations of EE2, bisphenol A (BPA), genistein and nonylphenol. Use of the ERE-GFP- Casper model shows chemical type and concentration dependence for green fluorescent protein (GFP) induction and both spatial and temporal responses for different environmental oestrogens tested. A semi-automated (ArrayScan) imaging and image analysis system was also developed to quantify whole body fluorescence responses for a range of different oestrogenic chemicals in the new transgenic zebrafish model. The zebrafish model developed provides a sensitive and highly integrative system for identifying oestrogenic chemicals, their target tissues and effect concentrations for exposures in real time and across different life stages. It thus has application for chemical screening to better direct health effects analysis of environmental oestrogens and for investigating the functional roles of oestrogens in vertebrates. The second model generated was an ERE-Kaede-Casper line developed via crossing of the ERE-GFP-Casper line and a UAS-Kaede line and screening subsequent generations for a desired genotype and homozygous expression of the transgenes. Kaede is a photoconvertible fluorescent protein that initially fluoresces green in colour and can be permanently converted to red fluorescence upon short exposure to UV light. The model has a silenced skin pigmentation and high sensitivity to oestrogenic chemicals comparable with the previously developed ERE-GFP-Casper model. Use of this model has identified windows of tissue-specific sensitivity to ethinyloestradiol (EE2) for exposure during early-life (0-48hpf) and illustrated that exposure to oestrogen (EE2) during early life (0-48hpf) can enhance responsiveness (sensitivity) to different environmental oestrogens (EE2, genistein and bisphenol A) for subsequent exposures during development. These findings illustrate the importance of oestrogen exposure history in effects assessments and they have wider implications for the possible adverse effects associated with oestrogen exposure.en_GB
dc.description.sponsorshipBiotechnology and Biological Sciences Research Council (BBSRC)en_GB
dc.description.sponsorshipAstraZenecaen_GB
dc.identifier.grantnumberBB/L01548X/1en_GB
dc.identifier.grantnumber620033640en_GB
dc.identifier.urihttp://hdl.handle.net/10871/27141
dc.language.isoenen_GB
dc.publisherUniversity of Exeteren_GB
dc.rights.embargoreasonChapter 5 of the thesis (title and authors below) is currently in preparation for submission to the journal "Environmental Science and Technology" for publication. This embargo request has been supported by my supervisor Prof. Charles Tyler. “Early life exposure to ethinylestradiol enhances subsequent responses to environmental oestrogens measured in a novel transgenic zebrafish” Green, JM; Lange, A; Scott, A; Wai, HA; Takesono, A; Brown, AR; Owen, SF; Kudoh, T; Tyler, CR.en_GB
dc.subjectEstrogenen_GB
dc.subjectOestrogenen_GB
dc.subjectTransgenicen_GB
dc.subjectZebrafishen_GB
dc.subjectEnvironmentalen_GB
dc.subjectScreeningen_GB
dc.subjectQuantificationen_GB
dc.subjectToxicologyen_GB
dc.subjectEstrogenicen_GB
dc.subjectEDCen_GB
dc.subjectFluorescenten_GB
dc.subjectAutomateden_GB
dc.titleDevelopment of Novel Transgenic Zebrafish Models and their Application to Studies on Environmental Oestrogensen_GB
dc.typeThesis or dissertationen_GB
dc.contributor.advisorTyler, Charles
dc.publisher.departmentCollege of Life and Environmental Sciencesen_GB
dc.type.degreetitlePhD in Biological Sciencesen_GB
dc.type.qualificationlevelDoctoralen_GB
dc.type.qualificationnamePhDen_GB


Files in this item

This item appears in the following Collection(s)

Show simple item record