Meeting Abstract
P1.139 Tuesday, Jan. 4 Subcellular Localization of Aquaporin-2 During Salinity Adaptation in the Ribbed Mussel KAPPER, M.A.; Central Connecticut State University kapper@ccsu.edu
During adaptation to increases in environmental salinity osmoconforming invertebrates typically modify the intracellular solute load by synthesis of free amino acids. In the ribbed mussel, Geukensia demissa, alanine is used as the immediate osmotic effector, with glycine and proline accumulating later. Even though intracellular fluids eventually come into osmotic equilibrium with the external environment following an increase in external salinity, there is a transitional loss of water from the cells as metabolic activity is redirected towards amino acid synthesis. I hypothesize that the magnitude of this water loss is modulated by the removal of aquaporin-2 water channel proteins from the cell membrane during the initial salinity challenge. Gills from mussels adapted to 15,oC and 15o/ooS were excised and incubated in aerated 30o/ooS artificial sea water at 15oC. Tissues were fixed and embedded in paraffin using standard histological techniques. Two µm sections were incubated with an anti-aquaporin-2 antibody overnight followed by a secondary antibody coupled to a fluorescent dye. Duplicate slides processed without the primary antibody served as negative controls. Fluorescence micrographs of gills from mussels adapted to 15o/ooS showed a relatively even distribution of aquaporin-2 around the periphery of the cells. Fluorescence from aquaporin-2 in gills that had been incubated at 30o/ooS for 30 minutes appear to show a concentration of fluorescence in the interior of the cells, away from the cell membranes. If removal of aquaporin from the cell membrane during salinity adaptation is confirmed, we hypothesize that the process is mediated by a cAMP linked G-protein system analogous to the mammalian kidney. Supported by CSU-AAUP grants to MAK.
