In all probability, natural selection began as ancient marine microorganisms were required to compete for limited resources. These pressures resulted in the evolution of diverse genetically encoded small molecules with a variety of ecological and metabolic roles. Remarkably, many of these same biologically active molecules have potential utility in modern medicine and biomedical research. The most promising of these natural products often derive from organisms richly populated by associated microorganisms (e.g., marine sponges and ascidians), and often there is great uncertainty about which organism in these assemblages is making these intriguing metabolites. To use the molecular machinery responsible for the biosynthesis of potential drug-lead natural products, new tools must be applied to delineate their genetic and enzymatic origins. The aim of this perspective is to highlight both traditional and emerging techniques for the localization of metabolic pathways within complex marine environments. Examples are given from the literature as well as recent proof-of-concept experiments from the authors' laboratories.

The concept of transfer function for organ performance (work output vs. biochemical input) is developed for skeletal and cardiac muscle under steady-state exercise conditions. For metabolic control by the ADP concentration, the transfer function approximates a Michaelis-Menten hyperbola. Variation of the work identifies metabolic operating points on the transfer function corresponding to ADP concentrations or to a ratio of inorganic phosphate to phosphocreatine that can be determined by phosphorus nuclear magnetic resonance. This operating point is characterized by the fraction (V/VJ) of maximal activity of oxidative metabolism in the steady state. This quantity appears to be useful in predicting the degree to which metabolic homeostasis is effective; poorly controlled metabolic states can readily be identified and are used in the diagnosis and therapy of metabolic disease in the organs of neonates and adults.Analytical biochemistry has great strengths in measuring the more stable components of cell bioenergetics, particularly ATP [as buffered by creatine kinase equilibrium in skeletal tissue, brain, and heart (1, 2)]. However, the more labile and indeed interesting components, phosphocreatine (PCr) and inorganic phosphate (Pi) are measured with significantly less accuracy for two reasons: (i) the breakdown of PCr during extraction in the interval between cessation of metabolism and assay and (ii) even more serious, the difficulty in distinguishing, by usual analytical techniques, the bound and free forms and the contents of different intracellular compartments (3).Phosphorus NMR (P NMR) is selectively sensitive to the unbound form of cell metabolites and affords a wholly noninvasive approach to the study of metabolic control in the cytoplasmic compartment of cells and tissues (4, 5). P NMR can be used to obtain the relative concentrations of PCr, Pi, and ATP with rapidity and with significant atcuracy (± 10% in a 1-min scan). These concentration ratios are of great usefulness and importance in the study of metabolic control in animal models, neonates, and adults. Additional information is available when the absolute values of tissue concentrations of PCr and Pi are calculated from the value of ATP, and also creatine, as determined by analytical biochemistry [or prospectively by proton NMR (6, 7)]. When ADP plays its usual role as a regulatory metabolite, its concentration is maintained too low to be directly determined by NMR but can be calculated from the PCr/P1 value with appropriate assumptions. Under these conditions, NMR becomes a very useful tool because the principal elements of energy metabolism are determined and thermodynamic values may be estimated. As we shall discuss here, rates of oxidative metabolism relative to their maximal rates for the particular tissue conditions may be determined with significant accuracy particularly when P NMR data are used to include the effect of pH. We shall show how P NMR can be used, particularly in tissues stressed with hypoxia, for the prediction of stabili...

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Three types of metabolic control of oxidative metabolism are observed in the various tissues that have been studied by phosphorous magnetic resonance spectroscopy. The principal control of oxidative metabolism in skeletal muscle is by ADP (or P1/phosphocreatine). This

As part of a continuing program to identify novel treatments for neglected parasitic diseases the Panama International Cooperative Biodiversity Group (ICBG) program has been investigating the antimalarial potential of secondary metabolites from Panamanian marine cyanobacteria. From over 60 strains of cyanobacteria evaluated in our biological screens, the organic extract of a Schizothrix species from a tropical reef near Piedras Gallinas (Caribbean coast of Panama) showed potent initial antimalarial activity against the W2 chloroquine resistant strain of Plasmodium falciparum. Bioassay guided fractionation followed by 2D NMR analysis afforded the planar structure of a new and highly functionalized linear peptide, gallinamide A. Subsequent degradation and derivatization methods were used to determine the absolute configuration at most chiral centers in this unusual new metabolite.