Meeting Abstract

P1.76  Jan. 4  Glycine betaine as the major osmolyte in larva and adult Fungia scutaria coral ANDRELL, R.M.*; LY, S.; HAGEDORN, M.; CARTER, V.L.; YANCEY, P.H.; Whitman College, Walla Walla, WA; Whitman College, Walla Walla, WA; Smithsonian National Zoological Park, Washington, DC, and Hawaii Institute of Marine Biology, Kaneohe; Hawaii Institute of Marine Biology, Kaneohe; Whitman College, Walla Walla, WA

Marine invertebrates and algae are osmoconformers that typically maintain cell volume by accumulating organic osmolytes, which may provide half or more of the cellular osmotic pressure. Thes osmolytes are primarily free amino acids and glycine betaine in most invertebrates, and small carbohydrates and dimethylsulfonopropionate (DMSP) in many algae. Corals with symbiotic algae (zooxanthellae) have been reported to obtain glycerol and DMSP from those symbionts, and it has been speculated that those solutes could serve as organic osmolytes. However, corals have not been fully analyzed for all potential osmolytes. We analyzed whole larvae and adult tissues of the coral Fungia scutaria for small carbohydrates, free amino acids, methylamines and DMSP. Larvae (from in vitro-fertilization) were raised from breeding F. scutaria adults, collected from various shallow reef flats in Kaneohe Bay at the Hawaii Institute for Marine Biology, University of Hawaii. Larvae were harvested on filters at days 1, 2, 3, 4, 5, and 6 in the absence of zooxanthellae, while some larvae on day 6 were infected with zooxanthellae. Tissues were stripped from pieces of adult coral placed in a large tube and centrifuged. HPLC revealed that glycine betaine constituted 80% or more of the total organic osmolyte-type solutes, in all larval stages and in adults. Contents of glycine betaine were as high as 200 mmol/kg tissue. The other osmotically significant solutes were taurine at 1- 5 mmol/kg in larvae and adults, and DMSP in adults only, at about 3 mmol/kg. In infected larvae, glycerol was detected at low levels (0.3-1 mmol/kg), but was not detected at other stages or in adults.