Aggregation of several forms of the molluscan muscle protein paramyosin at 

 low concentration and at low ionic strength was studied in the pH range 6 

 to 10 using transient electric birefringence techniques. In the lower part 

 of this pH range, aggregates exhibit negative birefringence, but this 

 changes to positive birefringence when the pH increases. Analysis of the 

 field-free birefringence decay transients of the paramyosin solutions showed 

 that all aggregates coexisted with paramyosin monomer and allowed a deter- 

 mination of the rotational diffusion constant of aggregates present at each 

 pl-l. The size and shape of these aggregates were estimated from their ro- 

 tational diffusion constants and were compared with the known character- 

 istics of larger aggregates such as paracrystals. Positively birefringent 

 aggregates appear to be staggered dimers at certain values of pH; at other 

 pH values these appear to be higher aggregates, probably formed by lateral 

 aggregation of monomer or dimer onto one of these staggered dimers. The 

 staggered dimers are formed by overlap of 200 to 600 A along each cylindri- 

 cal paramyosin molecule, in agreement with the 530 A overlap distance found 

 in paramyosin paracrystals by Cohen et al. (1971) . Some speculations are 

 given about the nature of the negatively birefringent species. - modified 

 authors' synopsis - J.L.M. 



2162 



Kyte, M. A., and K. K. Chew. 19 75. 



A review of hydraulic escalator shellfish harvester and its known effects 

 in relation to the soft shell clam, Mya arenaria. Univ. Wash. Sea Grant 

 Publ. WSG-75-2: 1-32. 



Details on Mercenaria mercenaria unlikely. Did not search beyond SUNY- 

 Stony Brook library. - J.L.M. 



2163 



Leibovitz, L. , T. R. Meyers, and M. Frey. 1976. 



A shell deforming disease of hard clams (Mercenaria mercenaria) . In Proc. 

 First International Colloquium on Invert. Pathol, and IXth Ann. Meeting, 

 Soc. Invert. Pathol. Printing Dept., Queens Univ.: 386-387. 



A shell abnormality of hard clam from Great South Bay, Long Island, N.Y. 

 was observed in wild and hatchery-grown planted stock. It was distinct 

 from shell abnormality related to mechanical injury, predator damage and 

 other abnormal shell changes including "Indian blanket" shell markings. 

 Greatest incidence of the disease was associated with early stages of shell 

 deformity in newly planted stunted hatchery reared stock. The stock suf- 

 fered a high mortality rate immediately following planting, but the cause 

 of the mortality was not known. Following the period of mortality, shell 

 deformities became progressively more pronounced in individual surviving 

 hard clams during growth from juvenile to adult marketing stages. The 

 disease was not seen in other areas of Long Island. The appearance of 

 affected Mercenaria mercenaria is described. - J.L.M. 



2164 



Malek, Emile A., and Thomas C. Cheng. 1974. 



Medical and Economic Entomology. Academic Press, New York, x + 398 p. 

 Chapter 8. Hematology. 



A second class of hemolymph cell occurs in some mollusks. These are smaller, 

 and have lower nuclear-cytoplasmic ratios. Such cells, designated hyalino- 

 cytes, have been found in Mercenaria mercenaria, - J.L.M. 



2165 



Malek, Emile A., and Thomas C. Cheng. 1974. 



Medical and Economic Malacology. Academic Press, New York, x + 39 8 p. 

 Chapter 12. Aquaculture. 



Mercenaria mercenaria is briefly covered. There is nothing new on biology, 

 and the aquaculture of mollusks generally is still in its infancy. - J.L.M. 



602 



