CEFAS: Effect of retinoid pollution, ocean acidification and hypoxia on development of oysters, mussels and scallops
About the award
The University of Exeter’s College of Life and Environmental Sciences, in partnership with the Centre for Environment, Fisheries and Aquaculture Science (Cefas), are inviting applications for a fully-funded PhD studentship to commence in September 2016 (or as soon as possible thereafter). For eligible students the studentship will cover UK/EU tuition fees plus an annual tax-free stipend of £14,198 for 3.5 years. The student would be based in Biosciences in the College of Life and Environmental Sciences at the Streatham Campus in Exeter.
Dr Tetsu Kudoh, University of Exeter
Professor Tamara Galloway, University of Exeter
Tim Bean, Cefas
Retinoid chemicals including nonylphenol and tributyltin (TBT) are major pollutants in rivers and coastal waters and have resulted in some of the largest environmental endocrine disruption events world-wide, with specific effects on the development and normal growth of molluscs. We found that pollutants (e.g. retionids) and hypoxia both reduce larval shell development and cause lethality. Negative impact of such environmental changes on larval development of commercially important shellfish (oyster, mussel and scallop) has been a concern for food security since TBT pollution events in the 1970s. This project will aim to understand the functional mechanisms through which such effects are mediated and aim to mitigate these issues through increased awareness, accurate risk assessment by in vitro assay development and by breeding animals for resilience to these stressors.
Retinoids (e.g. all retinoic acids) are crucial morphogens in vertebrate embryo development. Retinoic acid (RA) regulates hox gene expression and changes cell fates of early embryos. We have previously reported that tissue specific expression of the enzyme, Cyp26, which degrades RA, is crucial in regulating RA activity in specific domains of the embryo in the brain (Kudoh et al. 2002). We have recently cloned Cyp26 from the pond snail (Lymnaea stagnalis) and European common limpet (Patella vulugata) and conducted in situ hybridisation to examine gene expression patterns. The data suggest that Cyp26 is specifically expressed in the shell gland tissue in the trochophore larvae suggesting that titration of RA is required for development of the shell. Indeed, when we added RA in the culture water of the pond snail and limpet embryos, shell formation was specifically suppressed. Furthermore, we have also treated oyster (Crassostrea gigas) embryos with RA and confirmed that RA suppresses shell formation in bivalves too. It is also known that water acidification enhances the effect of RA in molluscan larvae.
We aim to identify molecular mechanisms of the effect of retinoid pollution and hypoxia (single as well as additive effects) by analysing gene expression profiles (transcriptome, QPCR and in situ hybridisation). These analyses will allow us to identify target genes and gene expression dynamics affected by the environmental changes. We will generate the first fluorescent transgenic biosensor oysters which can monitor stress responses caused by retinoid pollution, oxidative stresses and hypoxia. Such biosensor animals will be useful for assessing the impact of any pollution events and for risk assessing new chemicals as well as for learning real time stress responses and abnormalities caused by subtle environmental changes. We have strong expertise in transcriptome, QPCR, in situ hybridisation and technology for generating biosensor transgenic animals. Through these assays we will study variation in the sensitivity of animals to retinoid pollutants and, for example by identifying allelic variation of key genes, we will develop assays that allow for marker assisted selection of resilient stocks of animals.
This project will see an advancement of the experimental approaches for molluscan research on larval development and environmental changes, and will provide new information about mechanisms of population changes due to environmental changes. Ultimately this information will allow us to predict population changes of the species in the wild and develop methods to mitigate issues affecting food security and environmental sustainability.
This award provides annual funding to cover UK/EU tuition fees and a tax-free stipend. For students who qualify to pay UK/EU tuition fees, the award will cover the tuition fees in full plus a tax-free stipend of £14,198 per year for 3.5 years.
For further information please visit: http://www.exeter.ac.uk/studying/funding/award/?id=2127