166 J. AWAPARA 
MENDEL” in the muscle of a number of invertebrates, OkUDA?$ in some cephalopods 
and SCHMIDT AND WATSON?’ in the abalone (Haliotus). Stimpson, ALLEN AND AWA- 
PARA" compared the taurine concentration of some marine molluscs with the taurine 
concentration of fresh water and terrestrial molluscs. As shown in Table V, none of 
the fresh-water or terrestrial molluscs had taurine, at least not enough to be detected 
by paper chromatography. All the marine molluscs had taurine and some in very high 
concentration (Table VI). In Polinices duplicata the concentration of taurine was as 
TABLE VI 
TAURINE CONCENTRATION IN SOME INVERTEBRATES 
Values are expressed in wmoles/g fresh wt. 

Taurine 
concentration 

Penaeus aztecus 23 
Clibinarius vittatus 2 
Pagurus pollicaris 30 
Siphonaria lineolata 5 
Fasciolaria distans 12 
Busycon perversum 15 
Thais haemastoma 16 
Polinices duplicata 60 
Oliva sayana 6 
Arca umbonata 70 
Volsella demisus 10 
Crassostvea virginica 6 
Lithophage bisulcata Ti 
Loliguncula brevis 55 

high as 60 wmoles/g of fresh tissue. ALLEN AND AWAPARA®’ compared the rate of 
formation of taurine from cysteine in two molluscs: Rangia cuneata, a mollusc that 
lives in brackish water and is known to have traces of taurine and Mytilus edulis, a 
marine mollusc which as indicated before has a very high amount of taurine. Methods 
were developed to inject in the tissues of these molluscs small volumes of solution 
of |®°S|cysteine or methionine. Analyses of all 3°S-labeled compounds were then per- 
formed after various time-intervals. They found that taurine is formed from both cysteine 
and methionine. Sulfate was formed in both animals. Other intermediates detected 
were cysteic acid and cysteine sulfinic acid. Taurine formation from methionine, 
cystine or cysteine occurred by the same steps described for the rat?%. Differences in 
rates of formation were observed but not sufficiently different to account for the 
discrepancy in their taurine content. We postulated that taurine is in fact formed in 
both organisms but for unknown reasons R. cuneata loses its taurine to the medium 
whereas M. edulis concentrates it in the muscle. A similar situation was observed by 
AWAPARA* who showed that taurine is concentrated and held for long periods of 
time by the heart muscle of the rat, but other organs did not concentrate taurine nor 
hold it for long periods of time. In one experiment we showed that R. cuneata cannot 
hold injected taurine. This is shown in Fig. 2. A similar experiment was not possible 
for M. edulis because the high concentration of endogenous taurine prevented us 
References p. 174/175 
