. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 204 SUMNER I. ZACKS AND JOHN H. WELSH drolysis of the acetylocholine present in the incubation mixtures in two hours as evidenced by the failure of test aliquots to inhibit the spontaneous beat of the iso- lated heart. The same final concentration of acetylcholine (10~7 M) added to the bath and aliquots of incubation mixtures protected with 10~4 M physostigmine salicylate, completely inhibited the beat of the Venus hearts tested. Test concen- trations of acetylcholine (10~T M), added to the test hearts after the experimental
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 204 SUMNER I. ZACKS AND JOHN H. WELSH drolysis of the acetylocholine present in the incubation mixtures in two hours as evidenced by the failure of test aliquots to inhibit the spontaneous beat of the iso- lated heart. The same final concentration of acetylcholine (10~7 M) added to the bath and aliquots of incubation mixtures protected with 10~4 M physostigmine salicylate, completely inhibited the beat of the Venus hearts tested. Test concen- trations of acetylcholine (10~T M), added to the test hearts after the experimental aliquots had been tested, showed that the test hearts were still sensitive to acetylcholine. Thus, isolated and washed Venus amoebocytes as well as serum contain en- zymes capable of hydrolyzing acetylcholine. The observed complete inhibition of these enzymes by physostigmine salicylate 10~4 M indicates the presence of cholines- terase, since lipase and esterase are slightly inhibited by this concentration of physo- stigmine (Easson and Stedman, 1937; Richter and Croft, 1942). The presence of lipase or esterase in Venus amoebocytes cannot be excluded without additional evi-. FIGURE 1. Sample record of the response of the isolated Venus heart to aliquots of incubation mixtures, to detect the presence of acetylcholine. dence. The histochemical data, which will be presented below, indicate that a mixture of enzymes exists in the amoebocytes as well as in the intestine and heart muscle. PART II In order to obtain more information concerning the intracellular localization of esterases, recently developed histochemical methods were applied to amoebocytes, intestinal epithelium and heart muscle of Venus. These procedures have been used in combination with various enzyme inhibitors in an attempt to characterize the types of enzymes present. METHODS Nachlas and Seligman (1949) developed a procedure for the histochemical locali- zation of esterase and lipase in acetone-fixed tissues. Th
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
