Meeting Abstract

P2.79  Friday, Jan. 4  Aquaporins play a role in desiccation and freeze tolerance in larvae of the goldenrod gall fly, Eurosta solidaginis PHILIP, B.N.**; YI, S.-X.; ELNITSKY, M.A.; LEE, R.E.; Miami University, Oxford, OH; Miami University, Oxford, OH; Miami University, Oxford, OH; Miami University, Oxford, OH philipbn@muohio.edu

Survival of freezing, not only, requires organisms to tolerate ice formation, but also depends on the rapid redistribution of water and cryoprotective compounds between intra- and extra-cellular compartments. Aquaporins are transmembrane proteins that serve as the major pathway through which water and small uncharged solutes (e.g. glycerol) enter and leave the cell. Consequently, we tested the hypothesis that aquaporins play a critical role in the survival of freezing and desiccation in a naturally freeze-tolerant organism. We examined larvae of the goldenrod gall fly, Eurosta solidaginis, to determine whether aquaporins were present and if their presence promoted freeze tolerance of specific tissues. Immunoblotting with mammalian anti-AQP2, -AQP3 and -AQP4 revealed corresponding aquaporin homologues in E. solidaginis, whose patterns of expression varied depending on acclimation temperature and desiccation treatment. To examine the role of aquaporins in freeze tolerance, we froze fat body, midgut and salivary gland tissues in vitro in the presence and absence of mercuric chloride, a specific aquaporin inhibitor. Survival of fat body and midgut cells was significantly reduced when mercuric chloride was present. In contrast, survival of the salivary gland did not differ when frozen with mercuric chloride. Our results suggest that the aquaporins found in the fat body and midgut are mercury sensitive, while those in the salivary gland are not. Overall, this study supports our hypothesis that naturally occurring aquaporins in E. solidaginis are regulated during desiccation and promote cell survival during freezing.