Meeting Abstract

P3.213  Tuesday, Jan. 6  Aquaporin-3 expression correlates with seasonal acquisition of freeze tolerance in the goldenrod gall fly, Eurosta solidaginis PHILIP, B.N.; LEE, R.E.**; Miami Univ., Oxford. Ohio; Miami Univ., Oxford. Ohio philipbn@muohio.edu

Some invertebrates have evolved adaptations to survive freezing of their bodily fluids during subzero temperature exposure. The accumulation of cryoprotectants, such as glycerol, and the redistribution of water between body compartments play central roles in their capacity to survive freezing. The movement of glycerol and water into and out of the cell is facilitated by aquaporins, which are pore-forming transmembrane proteins. Recent studies demonstrated that there is a significant decrease in freeze tolerance when molecular movements through aquaporins are blocked. Larvae of the goldenrod gall fly, Eurosta solidaginis, are freeze-intolerant during the summer, but develop their capacity for freeze tolerance through the autumn. To determine whether aquaporin expression is correlated with their acquisition of freeze tolerance, E. solidaginis larvae were collected monthly, from July through January. As expected, larvae developed progressively greater levels of freeze tolerance through the autumn. Also, glycerol concentration increased in the larvae as the plant gall tissues around them senesced and dried. Following each field collection, membrane- and soluble-protein fractions were isolated from larval homogenates. Immunoblots using rat anti-AQP3, a water- and glycerol-permeable aquaporin, showed a gradual increase in membrane-bound AQP3 from July through January. In contrast, AQP3 proteins in the soluble fraction peaked in September and gradually decreased through December. These results support the hypothesis that AQP3 expression increases concomitantly with increasing freeze tolerance in E. solidaginis. Supported in part by NSF grant #IOB-0416720.