The mechanism of glycine betaine regulation in response to hyperosmotic stress in oyster mitochondria: A comparative study of Atlantic and Chesapeake Bay oysters

Abstract

AbstractMitochondria isolated from Crassostrea virginica gill take up14C‐choline and convert it to glycine betaine. Mitochondria from low salinity adapted oysters from both the Chesapeake Bay and Atlantic coast take up choline at similar rates, but the rate of glycine betaine synthesis is up to 4‐fold faster in the Atlantic oyster mitochondria. The choline uptake and glycine betaine synthesis rates are much higher (as much as 5‐fold, depending upon the concentration of choline) in mitochondria from high salinity adapted oysters from both populations compared to the rates found in the low salinity groups. Furthermore, the uptake and synthesis rates in the high salinity adapted mitochondria are similar between Atlantic and Bay oysters up to 5 mM choline. Above that concentration, the uptake and synthesis rates of mitochondria from the Atlantic oysters are greater than the rates in the Bay oysters (2. 5‐fold and 2‐fold, respectively). These results indicate that glycine betaine synthesis is regulated differently both between the two oyster populations and between the two acclimation salinities. © 1995 Wiley‐Liss, Inc.