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Glen Sweeney

Dr Glen Sweeney

Honorary Senior Lecturer

School of Biosciences


Our work concerns aspects of the molecular biology of farmed fish species. We have two main interests.

The nature and regulation of life cycle transitions in fish

All fish species go through a transition that converts the larva which emerges following hatching of an egg, into a juvenile that simply needs to grow to attain the adult phenotype. The most dramatic manifestation of the larval-juvenile transition is seen in flatfish metamorphosis, where there are dramatic morphological changes and a loss of external bilateral symmetry. We are studying metamorphosis in a major cultured flatfish species, the Atlantic halibut (Hippoglossus hippoglossus). Subtractive hybridisation is being used to identify genes that become activated during metamorphosis. Additionally the role of the endocrine system in metamorphosis is being investigated. In particular we are investigated the role of thyroid hormones, and thyroid hormone receptors in promoting halibut metamorphosis and the larval-juvenile transition in a non-metamorphic fish species, the sea bream Sparus aurata.

We are also conducting research into smoltification — the process by which freshwater salmon become adapted for life in salt water prior to their migration from river to sea. Subtractive hybridisation is being used to isolated genes that show differential expression during metamorphosis, and we have also cloned thyroid homrone receptors from salmon since thyroid hormones have a role in regulating smoltification.

Sex determination in fish

Unlike the simple XY/XX chromosomal sex-determining system of mammals, fish use a range of different strategies to determine sex. Some fish species have chromosomal sex determining systems analogous to those of mammals (XX/XY) or birds (ZZ/ZW), but in other species the are no morphologically distinct sex chromosomes, with environmental factors taking the lead role in sex determination. We are studying the role of candidate sex determining genes, particularly WT-1, and various members of the sox gene family, in sex determination in the European sea bass (Dicentrarchus labrax). Sea bass is of great interested because of the heavily skewed sex ratios (approx. 90% of offspiring are male), that are encountered on sea bass farms.


Recent Funding for research in my lab has come from the EU and the BBSRC.


  • Dr D. Power, Centre for Marine Sciences, University of the Algarve, Portugal
  • Professor A. Canario, Centre for Marine Sciences, University of the Algarve, Portugal
  • Professor B. Th. Bjornsson, Department of Zoophysiology, University of Goteborg, Sweden.
  • Dr K. Pittman, Department of Fisheries and Marine Biology, University of Bergen, 5020 Bergen, Norway
  • Ms H. Smaradottir, Fiskeldi Eyjafjardar Ltd. Glerargata 34, Akureyri, Iceland.
  • Dr S. Zanuy, Instituto de Acuicultura de Torre de la Sal (CSIC), Castellon, Spain
  • Dr C. Mylonas, Institute of Marine Biology of Crete, Iraklion, Crete, Greece.
  • Dr F. Piferrer, Institute of Marine Sciences, Barcelona, Spain
  • Dr A. Tandler, National Center for Mariculture, Eilat, Israel.
  • Professor A. J. Teale, Institute of Aquaculture, University of Stirling
  • Professor C. Secombes, Department of Zoology, University of Aberdeen
  • Dr S. Martin, Department of Zoology, University of Aberdeen
  • Professor D. Houlihan, Department of Zoology, University of Aberdeen