Papers in Marine Biology and Oceanography, Suppl. to vol. 3 of Deep-Sea Research, pp. 287-297. 



On the nature and action of coelenterate toxins* 



By John H. Welsh 

 The Biological Laboratories, Harvard University 



Summary — Tetramethylammonium, known to occur in sea anemones, has been thought to be one or 

 constituents of coelenterate nematocyst toxins. To test this suggestion it was first shown that the 

 tendency to drop legs, or autotomize, in the fiddler crab Uca numlax, was reduced by previous 

 injection of extracts of tentacles of two species of anemones and of Phy.sa/ia, the Portugucsc-man-of- 

 war. It was then found that injected tetramethylammonium chloride or acetylcholine had similar 

 actions to those of the extracts. 



Further experiments of a comparable nature were done at another location, using as a test animal 

 the shore crab, Hemigrapsus niidus. Extracts of tentacles of Metridiiiiih when injected into H. niulus, 

 produced spontaneous autotomy of walking legs and chelae, followed by a degree of paralysis 

 dependent upon the dose. 



After the injection of tetramethylammonium chloride into H. niulus there were no spontaneous 

 autotomies, but there was a type of paralysis similar to that produced by tentacle extracts. 



Tetraethylammonium chloride, and a related compound called Banthine, were highly effective in 

 blocking the autotomy-inducing and paralyzing actions of Metridiitm tentacle extracts. This is added 

 evidence that a quaternary ammonium base similar to tetramethylammonium occurs in coelenterate 

 tentacle extracts. 



When Metridium and Cyanea tentacle extracts were tested on an isolated mollusc heart, evidence for 

 the presence of an excitor amine was obtained. It appeared not to be histamine. Later experiments 

 strongly suggested that the material with the marked action on the molluscan heart was 5-hydroxy- 

 tryptamine, a known histamine-releaser and potent pain producer. 



Through the use of paper chromatography further evidence has been obtained for the presence of 

 5-hydroxytryptamine in extracts of tentacles of Metridium and Physolia. This approach has also 

 shown the presence of two or more quaternary ammonium bases, one of which has been tentatively 

 identified as urocanylcholine, also known as murexine. 



The pain producing factor in coelenterate tentacle extracts is probably 5-hydroxytryptaminc: 

 while paralysis could be due to two or more related quaternary ammonium bases such as tetramethyl- 

 ammonium and urocanylcholine. 



The painful and paralyzing nature of the " sting '" of certain jellyfishes and the 

 siphonophore, Physalia, is well known. Less well known is the fact that all coelenter- 

 ates possess stinging organelles, called nematocysts, which serve two main functions; 

 one, defence, and two, immobilization of prey for ease in feeding. The latter is well 

 illustrated by a hydra subduing and engulfing a large and active Daphnia. The ability 

 to produce a painful sting is not an indication of the amount of toxic substance prcseni 

 in the tentacles of a given species; rather, it is the ability of the nematocysts to 

 penetrate the skin. This ability varies greatly with species, and effective penetration 

 of human skin is restricted to the nematocysts of relatively few species of coelenterales. 

 For example, the sea anemone, Anemonia sulcata, has penetrants that enter the skin 

 of the finger sufficiently to cause a stickiness between the tentacles and the skin, but 

 seldom is there subsequent pain. However, when a tentacle of this species is placed 

 on the tongue, a painful and long-lasting burning sensation results, indicating that 



* This investigation was supported in part by a research grant (B-623) from the National Institutes 

 of Health, Public Health Service. 



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