and results are described. Reared in tanks with quahogs are sea hares for 

 alga control, and silversides and mummichogs, used in laboratory toxicological 

 studies. Culture of lobsters and salmon is also contemplated. - J.L.M. 



385 



Costello, D. P., M. E. Davidson, A. Eggers, M. H. Fox, and C. Henley. 1957. 



Methods for obtaining and handling marine eggs and embryos. Mar. Biol. 

 Lab., Woods Hole, Mass., Lancaster Press, Inc., Lancaster, Pa., xv + 247 p. 



Material is treated by Phyla. Venus mercenaria (p. 130-132) is one of 

 several pelecypods discussed. Callocardia convexa, which is similar in 

 appearance, is often found with M. mercenaria , and can be confused with it. 

 Callocardia is smaller than mature Venus , is white, and has a smooth margin 

 to its shell. Breeding season of hard clam is mid- June to mid-August, with 

 a peak from late June to early July in the Woods Hole region. Individual 

 batches will shed for about 20 days only. Water temp must be above the 

 critical level of 23 to 25°C. Details of procuring and handling material 

 are summarized from the literature. All papers cited are abstracted 

 elsewhere in this bibliography. - J.L.M. 



386 



Cottrell, G. A. 1964. 



Fractionation of binding particles of certain physiologically active sub- 

 stances from a molluscan ganglia (sic) . Am. Zoologist 4(4)': 409 (abstract) . 



Describes preliminary studies of binding of acetylcholine (ACh) , 5- 

 hydroxytryptamine (5-HT), and an unidentified cardio-excitatory substance in 

 ganglia of Mercenaria (Venus) mercenaria. Homogenates prepared in 1.1 M 

 glucose were separated into 3 primary fractions (SI, S2, and Su) by 

 differential centrif ugation. Further fractionation was achieved in a 

 discontinuous sucrose gradient of 5 solutions ranging in concentration from 

 1.0 to 2.4 M. Three quarters of the ACh was recovered in sediments SI and 

 S2. Slightly more than half of this was in S2. Distribution of 5-HT was 

 similar. Most of the unidentified factor was in sediments, most of it in 

 S2. When S2 was resuspended in 1.1 M glucose and centrif uged over the 

 sucrose gradient at 100,000 g for 90 min, partial separation of all 3 sub- 

 stances was achieved. Over 90% of ACh was at the top of the gradient, which 

 corresponded to the solutions 1.1 M glucose, 1.0 M sucrose, and half of the 

 1.3 M sucrose. More than 60% of 5-HT was in the bottom half of the tube and 

 most of this was below 1.7 M sucrose. Highest concentration of unidentified 

 factor was in the fraction 1.3 to 1.7 M sucrose, whereas none was found in 

 the most dense sucrose fraction where highest concentration of 5-HT was 

 found. - J.L.M. 



387 



Cottrell, G. A. 1966. 



Separation and properties of subcellular particles associated with 5- 

 hydroxytryptamine, with acetylcholine and with an unidentified cardio- 

 excitatory substance from Mercenaria nervous tissue. Comp. Biochem. Physiol. 

 17 (3) : 891-907. 



Seventy percent or more of acetylcholine (ACh) and 5-hydroxytryptamine (5-HT) 

 in Mercenaria ganglia is bound to particles which sediment when homogenates 

 of this tissue, prepared in 1.1 M glucose, are centrif uged at high speed. 

 Similarly, a large proportion of the unidentified cardio-excitatory factor, 

 Substance X, is particle bound in Mercenaria ganglia. Particles binding each 

 of these substances have been partially separated from each other by density 

 gradient centrifugation. ACh particles were mainly associated with the least 

 dense layers of the gradient, 5-HT with denser layers, and Substance X with 

 layers of intermediate density. A fraction of 5-HT particles has been 

 purified 20 times over the original homogenate. The level of ACh contami- 

 nation of this fraction, if any, was below the limit of detection. Particles 

 binding ACh and 5-HT release their active substances in a quantitatively 

 similar manner to changes in pH, hypotonicity and increased temp. These 

 substances apparently act as peripheral neurohumors and also mediate nerve 

 activity at central synapses in mollusks. Clam nervous tissue contains 



107 



