Reference: Bint. Bull.. 141: 167-175. (August. 1971) THE IHSTKIIUTION OF PHOSPI IOAKGININE AND PIIOSPIIO-CREATINE IN MARINE INYLRTEBRATLS ' MORRIS ROCKSTEIN Marine Biological Laboratory, Woods Hole, Massachusetts mid the University of Miami School of Medicine. Miami, Florida 33152 Despite the wide morphological, ecological and functional diversity of the two or more million species of animals which exist on earth, comparative biochemical studies emphasize the basic similarity, at the molecular level, of all animal life. This is true both as regards chemical replicating mechanisms, on the one hand, and intracellular enzyme and co-enzyme systems which are particularly concerned with energy transfer, storage, and utilization, on the other. The phylogenetic significance of the high energy phosphagens, phosphocreatine and phosphoarginine, was first suggested by the studies of Kutscher and Acker-mann (1926) who proposed the principle that creatine was the phosphagen of vertebrate muscle and that invertebrates should therefore be termed "acreatinate." More recent studies by Yuclkin (1954) and by Roche, Thoai and Robin (1957). who identified creatine phosphate as present in three other invertebrate phyla, have cast doubt on the original concept of Kutscher and Ackermann. and the inferences of Needham, Baldwin and Yuclkin (1932) and Baldwin and Needham (1937). as to the phylogenetic implications of differential distribution of the two phos-phagens. A recent review of Ennor and Morrison ( 1958 ) covered the scattered, later reports on the distribution of phosphocreatine in marine organisms. They concluded (page 665) that "phosphocreatine and phosphoarginine cannot be regarded as characteristic of the vertebrates and invertebrates, respectively, for, while phosphocreatine is a phosphagen characteristic of the vertebrates, no one phosphagen is characteristic of the invertebrates." However, even the early work of X'eedham (1932) ct a!., showed that creatine did occur in some of the echinoderms as well as the hemichordates, with the in-ference on their part, that this was evidence for a common ancestry for the echinoderms and the vertebrates. Other biochemical evidence by Bergmann, McLean and Lester (1943) and Bergmann (1949) and more limited embryological evidence by Breneman (1966) have also linked the echinoderms phylogenetically to the primitive chordates, particularly the hemichordates. However, the tech-niques of separation and identification of these two phosphagens, which have been employed in these earlier studies and upon which phylogenetic inferences were based, are either questionable or differ from one another significantly. The present study was therefore undertaken in an attempt to resolve the question of the possible phylogenetic interrelationship of the echinoderms and primitive chordates, suggested both by embryological and by Bergmann's quite different biochemical line of evidence. Accordingly, the distribution of the two phosphagens in representative species of four major classes of the Echinodermata 1 This study was supported in part by Grants No. HD 00571 and No. HD 00261 from the National Institutes of Health, and NSF Grant No. G-11664 and ONR Grant (to the Marine Biological Laboratory) No. 4785. 167
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