164 J. AWAPARA 
acids as well as the branched chain amino acids were present in small amounts. Proline 
was found in most of them in higher concentration than in most mammalian organs. 
ACKERMANN has analyzed a large number of invertebrates and invariably found large 
quantities of glycine in most of them. In the mussel Mytilus edulis he found a number 
of bases but glycine betaine was the most abundant of all !®. Since that time, ACKERMANN 
et al. have isolated glycine betaine from other invertebrates along with a number of 
new nitrogenous compounds. From the king crab (Limulus polyphemus) they obtained 
nearly all known a-amino acids and a number of other related substances like glycine 
betaine, choline, ergothioneine and others!’. From the sea snail Patella sp. he isolated 
also glycine betaine, choline, arginine, taurine and a number of other metabolites, 
some closely related to amino acids!§. From a tunicate Cronza intestinalis they isolated 
glycine and taurine’? and from the marine worm Nerets virens he isolated glycocy- 
amine, choline, lysine, leucine, tyrosine and a-alanine”’; he also showed the presence 
of large amounts of glycine. It is in fact tempting to ascribe an important function to 
glycine and its various derivatives: glycocyamine, glycine betaine and choline. It 
would be very interesting to study the biogenesis and catabolism of glycine in inverte- 
brates where this amino acid is abundantly present. The occurrence of glycine betaine 
and choline in most invertebrates suggest active transmethylation, a reaction which 
has not been studied extensively among invertebrates. In addition to those methylated 
derivatives a new and unique one was found by ACKERMANN ina giant sponge, namely 
taurobetaine. Although taurobetaine has not been discovered in any other organism 
it shows that methylations must occur even in the lowly sponge and with methyl 
acceptors not recognized until now such as taurine. The role of taurobetaine is not 
known. Other unique betaines have been known before the discovery of taurobetaine ; 
one such is butyrobetaine. 
Tosum up: There are some unique features in the distribution of non-protein nitrogen 
in invertebrates. Much of the non-protein nitrogen is present as a-amino acids and 
some derivatives. The concentration of free amino acids in invertebrates is very high 
as compared to the free amino acids of vertebrates. A marine environment does not 
account for this high concentration of free amino acids since fishes do not have more 
amino acids in the free form than mammals do. Whereas in mammalian organs there 
isa more even distribution of free amino acids, in invertebrates’ organs some amino 
acids make up the largest portion of the free amino acid nitrogen. Glycine and, as 
will be discussed later, taurine are found in nearly all species of invertebrates and in 
very large amounts. Glycine betaine is also found in the tissues of many invertebrates 
suggesting that it is formed by transmethylation in which glycine participates. High 
levels of free amino acids, it has been suggested, is a manifestation of osmoreguiatory 
mechanisms in some animals. Dietary factors could affect the distribution of free 
amino acids and related compounds but cannot account for a relatively uniform and 
unique pattern of distribution such as found in the crustacea discussed. 
From the standpoint of comparative biochemistry it would be more profitable to 
study taxonomically related species under uniform laboratory conditions. The con- 
tent and types of amino acids which are found in the invertebrates have given us many 
clues to fascinating problems. The next step is to study metabolic sequences and to 
compare rates of reactions in different species. The comparative study on urea forma- 
tion by BROWN AND COHEN?! is a good example of the interesting consequences of this 
type of study. 
References p. 174/175 
