2111 



Duke, Thomas W. 1967. 



Possible routes of zinc 65 from an experimental estuarine environment to 

 man. J. Water Pollut. Control Fed. 39(4): 536-542. 



A concrete-walled pond 30 x 60 m, adjoining the estuary surrounding Pivers 

 Island, N.C., was used as the experimental environment. Less than one per- 

 cent of the zinc 65 introduced into the water was accumulated by seafood 

 organisms. Among several organisms in the pond were 20 Meveenavia meveenavia 

 weighing 4.6 x 10 3 grams. Scallops, oysters, and clams are eaten by man and 

 they accumulated zinc 65 more rapidly and to higher levels than the other 

 organisms tested. Oysters and hard clams contained more zinc 65 in edible 

 tissues than did scallops. If all organisms from the pond were eaten by man 

 over a long period of time, he could have accumulated more zinc 6 5 from clams 

 than other organisms because edible portions of the clams had the highest 

 specific activity. These results cannot be extrapolated to include the pos- 

 sible movement of zinc 6 5 in an estuary under different conditions of pH, 

 temp, salinity, and different rates of exchange of water. As these conditions 

 vary, so would the movement of zinc 65. - J.L.M. 



2112 



Dykens, J. A., and C. P. Mangum. 1979. 



The design of cardiac muscle and the mode of metabolism in molluscs. Comp. 

 Biochem. Physiol. 62A(3): 549-554. 



The structure of the squid cardiac myofiber differs fundamentally from that 

 of lamellibranchs, most notably in mitochondrial and tubule density. Com- 

 pared with Mereenavia meveenavia, Lolliguncuta bvevis shows 252 beats/min 

 at 20°C compared with 10 for M. mereenavia, mitochondrial density (% cross- 

 sectional area) 50 to 80 compared with 5 to 20, and the heart muscle ob- 

 liquely striated compared with smooth. This information suggests that a 

 critical event in the evolution of the highly aerobic metabolism and great 

 swimming speed of decapod cephalopods, in which the oxygen-carrying capacity 

 of the blood is not especially high, was the replacement of a lamellibranch 

 type of cardiac myofiber with that found in the squid. - J.L.M. 



2113 



Edwards, Harold H., William H. Johnson, and Jacqueline P. Merrick. 1977. 



Comparison of solubility properties of a-paramyosin, 6-paramyosin, and acid- 

 extracted paramyosin. Biochem. 16(10): 2255-2260. 



We have found that acid-extracted paramyosin is very similar if not identical 

 to a-paramyosin, but that acid and a forms differ considerably from B- and 

 y-paramyosin. S-paramyosin precipitates abruptly from solution in a narrow 

 zone of pH below neutrality, and increases in ionic strength shift the zone 

 of precipitation toward lower pH values. In contrast, acid and a-paramyosin 

 show gradual aggregation with changing pH at lower ionic strength (<0.3) but 

 sharp transitions similar to B-paramyosin at higher ionic strength (>0.3). 

 Transitions were also found at lower pH (ca 4.0) which were not mirror images 

 of transitions at higher pH (ca 7.0). Viscosity measurements show that acid- 

 extracted paramyosin is close in behavior to a native extract obtained by 

 extraction in mild, nondenaturing media containing mixed antibiotics. Each 

 of these extracts differed considerably from 6-paramyosin. Mild, nonhydro- 

 lytic procedures employed by others to remove small, noncovalent bonded com- 

 ponents or to separate protein complexes were not effective in converting ot- 

 to B-paramyosin. Comparison of extraction procedures strongly supports the 

 suggestion of Stafford and Yphantis (19 72) that B- and y-paramyosin are 

 hydrolytic products of a-paramyosin and that the proteases responsible may 

 be of bacterial origin. - modified authors' abstract. - J.L.M. 



587 



