Arsenic reduced the amount of SGK mRNA in the gills of fish transferred from freshwater (FW) to seawater. Fish were adapted to freshwater (FW) for two weeks, then exposed to arsenic (12,000 ppb) or vehicle for 48 hours and then placed in seawater (SW) containing arsenic (12,000 ppb) or vehicle for 1 hr, 3 hr, 8 hr and 24 hrs. After the indicated times gills were isolated and SGK1 mRNA in control (hatched bars) and arsenic treated fish (solid bars) were measured as described in Methods. Data presented as percent of 0 time data. N=7/group. *P<0.05 versus control at each time point.