Details of Award
NERC Reference : NE/C002369/1
Unravelling the Molecular Mechanisms of Disruption of Sexual Differentiation in Fish Exposed to Oestrogenic and Androgenic Pollutants
Fellowship Award
- Fellow:
- Dr R van Aerle, University of Exeter, Biosciences
- Grant held at:
- University of Exeter, Biosciences
- Science Area:
- Freshwater
- Overall Classification:
- Freshwater
- ENRIs:
- Pollution and Waste
- Natural Resource Management
- Global Change
- Environmental Risks and Hazards
- Biodiversity
- Science Topics:
- Water Quality
- Pollution
- Ecotoxicology
- Environmental Genomics
- Abstract:
- Major worldwide attention has focussed on the possibility that disruption of reproductive systems by pollutants may be reducing the reproductive health of many wildlife populations, and possibly human populations too. Exposure to one group of chemicals, so-called endocrine disrupting chemicals (EDCs) in both freshwater and marine environments has been shown to alter the reproductive physiology and morphology of fish, resulting in the induction of female-specific proteins in male fish, skewed sex ratios, reduced sperm counts, and an increased prevalence of intersexuality. Fish are used as vertebrate models to study the effects of endocrine disruption, as most EDCs end up in the aquatic environment via effluent from sewage treatment works (STW). Extensive field studies have shown that an increased number of male roach (a member of the carp family) living in rivers that receive STW effluent had alterations in the reproductive system, with gonads that contained eggs and/or had female-like reproductive ducts. Other abnormalities observed included the induction of female-specific proteins in male fish, skewed sex ratios, and reduced sperm quality. Fish are particularly vulnerable to chemical exposures during the early life-stages and it has been shown in the laboratory that male fish exposed to oestrogenic EDCs during the period when the gonads are formed (gonadal sex differentiation) can develop eggs in their gonads and/or form female-like reproductive ducts. In a recent laboratory study, it has been shown that exposure of fathead minnow (a fish related to the carp) to ethinyloestradiol (EE2; a synthetic oestrogen, widely used in the contraceptive pill) during the period of gonadal sex differentiation, resulted in a feminisation of the male reproductive duct and the production of a female-specific protein that makes up the egg yolk in oviparous vertebrates (vitellogenin). Despite many studies on the effects of EDCs on reproductive development and function in fish, not much is known about how (i.e. via what mechanisms) these chemicals interfere with the reproductive system. The aim of this project is to identify the mechanisms of disruption of sexual differentiation after exposing fish to oestrogenic and androgenic pollutants. The research will take place at the University of Exeter, an internationally recognised institution for its contributions in the field of endocrine disruption. The project will involve a series of fish exposures and consists of 3 phases. During the first phase, a fish gene array will be established that includes a set of reproductive genes that play key roles in reproductive development and function. During the second phase, fathead minnow will be exposed to various doses of 2 well-established model chemicals, a natural steroid oestrogen (17b-oestradiol) and a synthetic androgen (17a-methyltestosterone), during the period of gonadal sex differentiation and grown until sexual maturity. Gene expression patterns (`signatures?) will be analysed at the end of the exposure and compared with conventional ecotoxicological endpoints, including vitellogenin induction, alterations in gonad structure, and the ability of fish to produce viable offspring (reproductive success). The experiment will be repeated with STW effluent and the responses compared with the `oestrogen? and `androgen? signatures, respectively. The final string to this project (phase 3) will be to conduct exposures of fathead minnow in a similar manner to the 3 chemicals, but this time samples will be taken at various time points during the exposure period. The same endpoints as studied in phase 2 will be analysed at the end of the exposure period. The results will allow the identification of molecular signalling pathways through which EDCs are able to cause disruption of reproductive development and function in fish.
- NERC Reference:
- NE/C002369/1
- Grant Stage:
- Completed
- Scheme:
- Directed Postdoc pre-FEC
- Grant Status:
- Closed
- Programme:
- Post Genomics Fellow
This fellowship award has a total value of £133,100
FDAB - Financial Details (Award breakdown by headings)
| Total - Staff | Total - Other Costs |
|---|---|
| £104,600 | £28,500 |
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