527 



DuPaul, William D. 1972. 



Mechanisms of isosmotic intracellular regulation in marine molluscs. Ph.D. 

 thesis, College of William and Mary, 90 p. 



Salinity caused changes in concentration of free amino acids and in the 

 activities of alanine and aspartate aminotransferase were measured in gill 

 tissue of Mevoenavia mevoenavia, My a, and Spisula. Largest change in con- 

 centration of an individual free amino acid due to a salinity increase was 

 noted for alanine which had a 5195% increase in Mevoenavia, and a 411% and 

 282% increase in Mya and Spisula. Changes in concentration of alanine were 

 reflective of salinity induced changes in amino transferase activities. 

 Aspartic acid can serve as an indicator to determine metabolic pathways 

 which are active in the process of intracellular osmotic regulation. Syn- 

 thesis of alanine for osmoregulatory purposes is directly related to meta- 

 bolic pathways involving synthesis of pyruvate. - J.L.M. 



528 



DuPaul, William D., and Kenneth L. Webb. 1974. 



Salinity-induced changes in the alanine and aspartic aminotransferase 

 activity in three marine bivalve molluscs. Arch. Internatl. , Physiol. 

 Biochim. 82(5): 817-822. 



Meraenaria mevoenavia, soft clam, and surf clam accumulate intracellular 

 alanine when environmental salinity increases. At seawater salinities 

 alanine makes up 50% to 90% of the -total free amino acid (FAA) pool. The 

 experimental increase in salinity was from 20°/°° to 30°/°°. The response 

 had 2 major components, a "fast component" which acted during initial 

 phases of osmotic stress for 2 days and a "slow component" for longer term 

 adjustment. The fast component is important in preventing excessive tissue 

 water loss and cell volume changes during periods of rapid osmotic 

 adjustment. Large increases in alanine concentration occurred in Mya and 

 Spisula during the first 2 days of stress, and aspartic acid concentration 

 decreased in the same period. On the other hand, the fast component in 

 Mevoenavia consisted of a large increase in taurine concentration. The 

 slow component response consisted largely of a further increase in the 

 fast component constituent. In M. mevoenavia concentration of alanine 

 also increased considerably. Alanine aminotransferase levels were higher 

 in S. solidissima than in the other 2 species and changed during the 

 experiment. In all 3, activity levels were the same at the end as at the 

 start of the experiment. In the 1st day alanine aminotransferase increased 

 in surf clarr. and soft clam as alanine concentrations rose. In hard clam, 

 where the large increase in alanine is delayed, alanine aminotransferase 

 decreased daring the first day. Aspartic aminotransferase activity 

 decreased slightly in Mevoenavia and did not regain the original level. 

 Metabolic pathways for alanine accumulation appeared similar to those 

 described for invertebrate facultative anaerobiosis. - J.L.M. 



529 



Eagar, R. M. C. 1978. 



Shape and function of the shell: A comparison of some living and fossil 

 bivalve molluscs. Biol. Rev. 53: 169-210. 



This review paper cites the work of Stanley (1975) , abstracted elsewhere 

 in this bibliography. - J.L.M. 



147 



