mercenene occurs in more than one species, and its presence is therefore 

 unlikely to be the result of a selective feeding device, concentrating 

 mercenene produced by other organisms. - J.L.M. 



2119 



Epstein, Henry F., Bruce J. Aronow, and Harriet E. Harris. 1976. 



Myosin-paramyosin cofilaments: Enzymatic interactions with F-actin. Proc. 

 Natl. Acad. Sci. USA 73(9): 3015-3019. 



Interaction of paramyosin and myosin was studied by enzymological methods. 

 Paramyosin from adductor muscles of Meroenaria meroenaria inhibits the 

 actin-activated, Mg ++ -requiring, ATPase of clam-adductor and rabbit skeletal 

 muscle myosins. Myosin and paramyosin must be rapidly coprecipitated for 

 this inhibition. Incubation with F-actin in the absence of ATP does not 

 alter this effect. This inhibition follows a hyperbolic function with 

 respect to paramyosin concentration. Slow precipitation by dialysis of 

 myosin and paramyosin together leads to copolymers with actin-activated 

 ATPase equivalent to that of slowly formed myosin filaments. Both kinds of 

 slowly formed filaments have enzymatic properties distinct from those of 

 the rapidly precipitated proteins. Paramyosin is competitive with F-actin 

 for their effects upon myosin. The apparent affinity of myosin for F-actin 

 is markedly reduced by association with paramyosin, but the extrapolated 

 maximal velocity of actomyosin is unaffected. The specificity of this inhi- 

 bition is strongly suggested by marked quantitative differences between 

 native and cleaved paramyosins. No inhibition of intrinsic myosin ATPase 

 by paramyosin was seen. These studies suggest that at least two types of 

 condition-dependent association between myosin and paramyosin are possible. 

 One class of interaction is associated with enzymic inhibition in rapidly 

 coprecipitated filaments, whereas slowly formed cofilaments exhibit cata- 

 lytic activity similar to that of identically treated myosin and have a 

 characteristic 14.5 nm axial repeat. - modified authors' abstract - J.L.M. 



2120 



Eversole, Arnold G. , William K. Michener, and Peter J. Eldridge. 1980. 



Reproductive cycle of Meroenaria meroenaria in a South Carolina estuary. 

 Proc. Natl. Shellf. Assn. 70: 22-30. 



Hatchery seed of M. meroenaria planted at two tidal locations and at three 

 clam densities were sampled for three yrs . Gonadal development was deter- 

 mined histologically and related to clam size and experimental treatments. 

 Male gametogenesis preceded female development and a 9.5:1 male to female 

 sex ratio occurred during the first yr. Equal numbers of males and females 

 were approached in the 2nd yr 'and maintained through the 3rd yr. Changes 

 in % lumen; in % lumen filled with oocytes or spermatocytes, spermatids, and 

 spermatozoa; and the number and size of ovocytes were used to delineate 

 spawning and tissue regeneration periods. Spawning lasted for approximately 

 6 months with peaks in May and June and in September and October. Spawning 

 was followed by rapid regeneration of gonadal tissue. Shell length, tissue 

 wet weight, and internal shell volume varied significantly between sexes 

 and developmental stages of clams. Females were longer, weighed more, and 

 had more space within the shell than male clams. No histological differ- 

 ences were detected between clams from different densities or tidal loca- 

 tions. Age, size, and sex relationships to gonadal development are pre- 

 sented with a discussion of seasonal gonadal changes. - modified authors' 

 abstract - J.L.M. 



2121 



Figley, Bill, and Ray Townsend. 1980. 



Fish facts: Hard clam. The Fisherman (New Jersey, Delmarva and Hatteras) 

 8(36) : 15. 



A brief review of the biology of the hard clam (Mereenaria meroenaria) 

 covers common names, range, size, food, habitat, spawning, and predators. 

 It contains nothing new. In New Jersey the commercial fishery has had two 

 peaks, one in the early 1950s, the other in the late 1960s. The decline in 

 the 1950s was caused in part by the closing of shellfish areas from pollution. 



590 



