PHYLOGENY AND THE DISTRIBUTION OF CREATINE IN INVERTEBRATES

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Abstract
1. Fifteen species of invertebrates from seven phyla were examined for the presence of creatine, guanidinoacetic acid, and transamidinase. 2. None of the animals which possessed creatine had detectable levels of transamidinase. All animals which possessed guanidinoacetic acid also possessed transamidinase activity. A third group of invertebrates was formed of those species in which neither of the guanidine compounds nor transamidinase could be demonstrated. 3. Attempts using various procedures to obtain synthesis of creatine from appropriate precursors in those organisms in which it was found were uniformly negative. 4. Accumulation of creatine from very dilute solution in the ambient medium was demonstrated for all of the invertebrates in which creatine was found. 5. In Glycera and Saccoglossus, both of which possess creatine, creatine-C14 obtained from the ambient medium persists as creatine for at least 96 hours. 6. Other organisms which do not normally possess creatine also showed the ability to accumulate it from dilute solution. Evidence is presented that such animals eliminate creatine and may degrade it in the process. 7. These findings are discussed and their possible significance for phylogeny considered. It is suggested that the creatine found in the invertebrates examined here may be exogenous in origin. Thus, its presence may be adventitious and its use as phosphagen opportunistic.