Sea bream aquaculture has grown rapidly in importance in the EC, particularly in Southern Portugal. However, its further development as a valuable source of nutrition and of employment is being hindered by the high cost of production of larvae, which have a high mortality rate and incidence of malformations during development. Thyroid hormones are known to play a crucial role in the development and growth of vertebrates, but our understanding their role in fish development is still very limited. The aim of the project is to elucidate the role of thyroid hormones in sea bream development, both normal and abnormal by applying a combination of techniques to produce a comprehensive study of thyroid receptor levels and function and thyroid activity. Poly(A)+ RNA will be isolated and used to synthesise cDNA for ligation into vector 2 zap for packaging into phage particles to construct a cDNA library. The cloned genes will be used to prepare highly specific probes for the detection and quantification of thyroid hormone receptor RNA's by means of Northern and slot blot analysis. This will allow the assessment of the level of expression of the genes for the receptors in important tissues during both normal and abnormal larval development and subsequent growth and maturation. The results will be used in conjunction with concurrent measurement by radioimmunoassay of blood levels of the thyroid hormones and complimentary radio-ligand assay of receptor level and occupancy by hormone, in an investigation of the precise role and actions of thyroid hormones in early development, survival and growth of the fish to maturity. In addition, the effects of experimental intervention to alter thyroidal and environmental influence on larval development and growth will be investigated, with analysis of receptor gene expression, receptor function, and thyroid hormone levels to determine the precise effects of the treatments on thyroid function and the target tissues for the hormones.
Funding SchemeCSC - Cost-sharing contracts