Salt and water balance in the oligohaline clam, Rangia cuneata II. Accumulation of intracellular free amino acids during high salinity adaptation

During adaptation to an increase in ambient salinity (2–20 ppt) the estuarine clam Rangia cuneata enlarges the pool of free amino acids in adductor muscle fibers by more than five‐fold (>300 μM/gm dry wt). The process can occur under anaerobic conditions, but oxygen is critical to survival during high salinity adjustment. It is suggested that the pool may be enlarged by de novo synthesis, via a modified form of glycolysis perhaps involving the direct amination of pyruvate to form alanineutilizing free ammonia.