FREE AMINO ACIDS IN INVERTEBRATES Cy /aL 
of 5-hydroxytryptamine in tissues of invertebrates. The latter is formed by the decar- 
boxylation of 5-hydroxytryptophane. Spermine has been isolated by ACKERMANN” 
from the tunicate Czona intestinalis. 
An interesting compound, N-acetyltyramine has been isolated from the silkworm 
Bombyx mort by BUTENANDT ef al.”. 
Simpson” using a method for separating amines from amino acids’? detected a 
number of amines 1n extracts of all 17 marine species studied but none were identified. 
WHAT IS THE MAJOR SOURCE OF FREE AMINO ACIDS 
IN AQUATIC INVERTEBRATES? 
In Figs. 1-5 are shown chromatograms of extracts from whole animals. It is imme- 
diately apparent that there are great differences in patterns. As stated in the preceding 
discussion, glycine was very abundant in crustaceans and taurine in marine molluscs. 
This rather uneven distribution cannot be explained on the basis of diet. Many of the 
organisms studied have similar feeding habits and were obtained from the same area; 
yet, their free amino acid pattern Is quite different. Marine gastropods have abundant 
quantities of taurine, but their terrestrial counterparts have none. In Fig. 7 one can 
see that the land snails have a relatively similar pattern. Glycine is present in very 
small amounts or not present; taurine is absent; glutamic acid is present in relatively 
higher concentration and so is aspartic acid. There are no detectable amounts of 
branched chain or aromatic amino acids (in the range studied which is 50 mg of tissue 
per chromatogram). The land snail Otala lactea was analyzed after 6 months of star- 
vation and compared with specimens of fed snails. The chromatograms are shown in 
Fig. 7 and it is apparent that the differences are relatively small. In the same Fig. 
are shown chromatograms of a herbivorous snail. The carnivorous snail Euglandina 
singlyana feeds on the herbivorous snail Bulimulus. There is relatively little difference 
in the two patterns. 
It should be interesting to study sulfur metabolism in land snails. The pathway 
of methionine and cysteine metabolism are similar in nearly all organisms studied and 
there is ample evidence to show that taurine is formed in the marine gastropods. 
Land gastropods must metabolize sulfur in a different manner and it should be studied. 
Basically the biochemical events occurring in invertebrates must be the same or 
very similar to those occurring in the mammal. But the differences which one finds, 
however small, are interesting clues to biochemical evolution. Amino acids are an 
important group of compounds and the patterns, or “finger prints” as ROBERTS 
calls them are expressions of their metabolic activities. I believe that there is sufficient 
evidence to support the view that these “finger prints” are not fortuitous, that they 
do not represent dietary habits, but that they represent a picture of the metabolic 
activities of these organisms. They represent the balance between formation or 
accumulation of these substances, and disposition of them by catabolic reactions or 
by some excretory process. It has been suggested that free amino acids maintain 
osmotic balance in marine invertebrates. This is probably true, but this is only one 
function. Is this an adaptation to a marine environment? The question needs to be 
answered. Before it can be answered we need to know far more about metabolism of 
amino acids in invertebrates. 
References p. 174/175 
