Water Transport and Aquaporin Expression in Fish

One of the major differences between terrestrial and aquatic vertebrates is that the latter group have a potentially greater difficulty in maintaining osmotic homeostasis because they are surrounded by an external environment which is almost always in osmotic dis-equilibrium with their body fluids. In comparison to terrestrial animal species, aquatic organisms such as teleost fish may well possess a distinct set of mechanisms in order to adapt and survive the osmotic challenges posed by the seawater (SW: hyper- osmotic) or freshwater (FW: hypo-osmotic) environments. However, to date, little is known about how these mechanisms manifest themselves at the molecular level. In order to begin an evaluation of which proteins may be involved in osmoregulation in both the freshwater and marine environments, investigations have been initiated using the euryhaline teleost the European eel (anguilla anguilla) which naturally inhabits both environments.