RUI: The role of aquaporin channels in the eel intestinal water influx pathway during salinity acclimation

Eels migrate from rivers to the sea to breed and when they do so, one of the main challenges they face is that they must cope with the increase in salinity. In seawater, teleosts (bony fishes) lose water to the environment and in order to overcome this problem, they drink seawater. The intestine absorbs both salts and water, but the excess salts are excreted by the gills. It is not known how water absorption takes place in fish intestines and the goal of this project is to use molecular, biochemical, and physiological approaches to determine if water transport proteins, aquaporins, are involved in this process. One aspect of this project will reveal whether aquaporin proteins are in the correct location in intestinal cells to absorb the water. In addition, the functional characteristics of these proteins will be determined by expressing them in Xenopus (frog) oocytes and studying their transport characteristics. Eels will be transferred from freshwater to seawater, mimicking their natural migration, to test the hypothesis that there should be an increase the production of intestinal aquaporins that corresponds to the increased water absorption seen during acclimation to seawater. In addition, the importance of these proteins in intestinal water transport will be demonstrated by determining the rate of intestinal water transport after the levels of aquaporins are lowered by interfering with the intestinal cell's ability to synthesize these proteins. The project will not only have a major impact on understanding how fish are adapted to living in seawater, but will also increase the general level of knowledge concerning water transport processes in other animals. This project will involve the training of graduate and undergraduate students at both Georgia Southern University and Mount Desert Island Biological Laboratory.