during development from eggs to adults by Brookbank and Whiteley (19$U). 

 Xanthine oxidase, uricase, allantoinase, and allantoicase also were found 

 in the eggs. 



Much speculation exists concerning the origin and significance of 

 TMA. oxide in fish muscle and blood. Formerly believed to be present only 

 in marine fish (Kutscher and Ackermann 1933 and Baldwin 1952), it has been 

 shown to occur in significant but smaller amounts in fresh-water species 

 (Cook 1931, Reay 1938, and IAntzel et al. 1939). Reay found that elasmo- 

 branchs contain more TMA oxide than do teleosts. Suyama and Tokuhiro 

 (195U b) also studied the distribution of TMA oxide in elasmobranchs. 



In contrast to the blood of elasmobranchs, the blood of marine tele- 

 osts has no appreciable TMA oxide (Norris and Benoit 19 hS)» Norris and 

 Benoit also reported the oxide to be of general occurrence in marine Orus— 

 acea,which includes the lobster (Reay 1938)* For a more detailed comparison 

 between various fresh- and salt-water fish, see the review on nitrogenous 

 extractives in fish by Shewan (195>1). As was pointed out by Shewan, en- 

 vironment, seasonal variation, size, and age all can affect the TMA oxide 

 content. His work shows that different muscles also have different TMA 

 oxide content; the tissue forming the dark lateral line of both herring 

 and tunny have about half the content of the rest of the skeletal muscle. 

 Similar differences also were found between the white and red muscles of 

 fish by Endo and Shimidu (1955). The content of TMA and TMA. oxide of 

 numerous species of fish occurring near Bombay has been reported by Joshi 

 et al. (1953). TMA oxide has been found in the skin of the octopus (As- 

 ano and Sato 19!>U), but in shellfish muscles, the amounts are relatively- 

 low (Simidu et al. 19!?3)« 



TMA oxide may be the end product of protein metabolism, but enzymes 

 capable of oxidizing TMA in TMA oxide, such as occur to mammals, are ap- 

 parently lacking (Shewan 19£l). The difference in TMA oxide content be- 

 tween marine and fresh-water species is reflected in other organisms used 

 as food by these animals. Fresh-water aooplankton contain a very low 

 concentration of the oxide, whereas marine plankton have levels comparable 

 to other marine species (Reay 1938). Feeding experiments carried out with 

 young salmon (Benoit and Norris I9I6) indicate that the origin of TMA 

 oxide is exogenous in this species, mien diets free from TMA oxide were 

 fed, little or no TMA oxide was found, but some retention occurred when 

 the oxide was included in the diet. TMA oxide reductase activity in the 

 dark muscle of albacore and frigate mackerel has been demonstrated by 

 the reduction of aseptically added TMA oxide (Kawabata 1953). Immediately 

 after catch, large amounts, of free trimethylamine were found in the dark 

 musclej these amounts increased on incubation. No increase in free tri- 

 methylamine occurred in white muscle, nor was there any reduction 01 

 added TMA oxide. The reaction was found to be sensitive to both cyanidLe 

 and heat. Nickerson et al. (1950J found only slight increases in TMA 

 content of sterilized fish fillets, indicating very low amount of any 

 naturally occurring TMA oxide reductase. Since elasmobranchs show es- 

 pecially high concentrations of TMA oxide in all body fluids and tissues, 

 the base probably serves as an osmoregulatory factor (Reay 1938 and Shewan 

 1951). TMA oxide therefore may not be entirely of exogenous origin and 



26 



