intestine was unexpected. The pigment appears to be a lipofuscin, closely 

 related to ceroid observed in cirrhotic and vitamin E-deficient animals. 

 The relation of excretory pigment to digestion is suggested by its absence 

 in starved animals. - modified author's summary - J.L.M. 



2066 



Zacks , Sumner I., and John H. Welsh. 1953. 



Cholinesterase and lipase in the amoebocytes, intestinal epithelium and heart 

 muscle of the quahog, Venus mercenaria. Biol. Bull. 105(1): 200-211. 



Homogenates of whole Venus mercenaria neart hydrolyze acetylcholine (ACh) and 

 benzocholine slowly. Enzymatic activity of such homogenates is the sum of 

 that contributed by amoebocytes, intestinal epithelium, and heart muscle. 

 Isolated amoebocytes hydrolyze ACh, and the enzyme responsible is inhibited 

 by 10~4m physostigmine, indicating presence of cholinesterase. Serum 

 cholinesterase and lipase are present in amoebocytes, intestinal epithelium, 

 and heart muscle. Greatest lipase activity is present in amoebocytes and 

 intestinal epithelium. Serum cholinesterase activity is greatest in 

 ventricular muscle. Potentiation of the action of ACh on isolated Venus 

 heart by physostigmine is caused by inhibition of serum cholinesterase in 

 amoebocytes and especially in heart muscle. Presence of varying levels of 

 lipase in intestinal epithelium of Venus supports the suggested presence of 

 extracellular lipolytic enzymes in certain mollusks. In Venus amoebocytes, 

 cholinesterase activity is associated with structures which stain supravitally 

 with Janus green B. The role of serum cholinesterase, in sera or in tissues, 

 is not known. A digestive role might be suspected in Venus because the enzyme 

 occurs in amoebocytes and intestinal epithelium. - modified authors' summary. 

 - J.L.ft. 



2067 



Zafiriou, 0., K. J. Whittle, and M. Blumer. 1972. 



Response of Asterias vulgaris to bivalves and bivalve tissue extracts. 

 Mar. Biol. 13(2): 137-145. 



Experiments were conducted with Crassostrea virginica, Mytilus edulis, Mya 

 arenaria, and Venus mercenaria. There was little variation in response to 

 soluble homogenates of different shellfish species. A. vulgaris approached 

 very dilute tissue homogenates; A. forbesi did not approach oyster solutions. 

 Asterias species distinguished between intact prey and injured tissue. 

 Conversion of normal prey to injured tissue by predation may be a factor in 

 forming feeding aggregations. Considerable variability in behavior of sea 

 stars was noted. Poor flow conditions alone did not explain seemingly 

 contradictory results. - J.L.M. 



2068 



Zakaria, Sheryl P. 1979. 



Depuration - As it relates to the hard shell clam of Narraganset (sic) Bay, 

 Rhode Island. Iji Proc. Northeast Clam Industries: Management for the 

 Future. Ext. Sea Grant Advisory Program, U. Mass., and MIT Sea Grant Pro- 

 gram, SP-112: 109-119. 



There is a potential $1.5 million of harvestable quahogs (Mercenaria 

 mercenaria) in areas of the Bay presently closed to shellf ishing, or open 

 only conditionally. The harvest could be nearly doubled if these areas 

 could be harvested. There has been a steady increase for the past 12 yr in 

 numbers of fishermen licensed, but a decline in total bushels harvested. 

 The decline cannot be attributed to a decline in fishing effort because the 

 amount of closure has been about the same. The total area closed has increased, 

 however. The value per bushel has increased from a low in 1965 of $5.75 in 1965 



573 



