1298 



Merrick, Jacqueline P., and William H. Johnson. 1975. 



Further characterization of alpha paramyosin: reduced vs. oxidized forms. 

 Biophys. J. 15(2) Pt 2: 158a (abstract). 



Alpha paramyosin, a molecule which appears to be about 5% larger than the 

 classical ethanol preparation extracted from Meraenaria meraenaria, is 

 believed to be the native paramyosin species. Alpha-reduced R-paramyosin 

 differs from the oxidized form in several respects. It is generally more 

 soluble than alpha-oxidized, over an ionic strength range from 0.2 to 0.45M. 

 Its phase change from monomer to aggregate is more abrupt and occurs between 

 0.35-0.25M at pH 7. When ionic strength is held constant at 0.35M, and pH 

 is decreased from 7.0 to 6.7, alpha-R-paramyosin solubility falls off at a 

 more rapid rate than that of the oxidized form. Certain mollusks accumulate 

 lactate as a metabolic end product of the glycolytic scheme. In presence of 

 50nM lactate at pH 7.0, alpha-R-paramyosin begins to aggregate at a higher 

 ionic strength than the control without lactate, forming large birefringent 

 needles, as seen in phase contrast microscopy. These studies suggest that 

 alpha-R-paramyosin is a physiologically poised system. Conformational 

 changes in the thick filament paramyosin core, possibly leading to the 

 catch state, could occur from very small changes in pH, ionic strength, 

 and presence of certain metabolites such as lactate. - J.L.M. 



1299 



Merrill, Arthur S. 1971. 



Symposium on commercial marine mollusks summary. In Symposium on Commercial 

 Marine Mollusks of the United States. Am. Malacol. Un., Inc., Ann. Repts . for 

 1970: 38-40. 



Meraenaria mereenaria is compared with other commercial mollusks in volume and 

 landed value of production. Oyster was the most valuable, surf clam the 

 largest offshore fishery. Hard clam produced only 1/3 the volume of the surf 

 clam fishery, but exceeded it in value. Water pollution is an outstanding 

 problem. Many problems of the molluscan shellfish industry could be solved, 

 and the industry will continue to be an important part of the fishery economy. 

 - J.L.M. 



1300 



Merrill, Arthur S., and Robert W. Hanks. 1969. 



The Bureau of Commercial Fisheries Biological Laboratory at Oxford, Maryland, 

 meeting the problems of the shellf isheries . Bull. Assn. Southeastern Biol. 

 16(4) : 103-106. 



Meraenaria (Venus) meraenaria is not mentioned. - J.L.M. 



1301 



Merrill, Arthur S., and Helen S. Lang. 1971. 



Pollution and commercial marine mollusks. In Symposium on Commercial Marine 

 Mollusks of the United States. Am. Malacol. Un. , Inc., Ann. Repts. for 1970: 

 36-38. 



This brief general review mentions a few species but not hard clam, although 

 it is applicable in general. Water pollution affects commercial mollusks in 

 2 ways, by altering environment so that they cannot survive, or by con- 

 taminating them so that they are unfit for human consumption. They are 

 particularly susceptible because most species live in areas where pollution 

 is most likely, and cannot move to more favorable waters. Kinds of pollution 

 are fresh water, pesticides, domestic sewage, wastes from agriculture and 

 animal husbandry, heavy metals, petrochemicals, pulp mill wastes, radioactivity, 

 detergents, and waste heat. Mollusks can concentrate trace substances to 

 levels much greater than in natural environment, which can not only cause 

 physiological upsets to the animals, but also to man. Thermal pollution is 

 perhaps the only type that might be used to advantage by the shellfish 

 industry. - J.L.M. 



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