J. Appl. Cryst.の発刊に際して

The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. 
The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. 
The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. 
The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

Influence of Diet On the Distribtion of Nitrogen Isotopes in Animals

https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Natural products: a continuing source of novel drug leads.

Natural products have been a rich source of compounds for drug discovery. However, their use has diminished in the past two decades, in part because of technical barriers to screening natural products in high-throughput assays against molecular targets. Here, we review strategies for natural product screening that harness the recent technical advances that have reduced these barriers. We also assess the use of genomic and metabolomic approaches to augment traditional methods of studying natural products, and highlight recent examples of natural products in antimicrobial drug discovery and as inhibitors of protein-protein interactions. The growing appreciation of functional assays and phenotypic screens may further contribute to a revival of interest in natural products for drug discovery.

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The re-emergence of natural products for drug discovery in the genomics era

In an ongoing survey of the bioactive potential of microorganisms associated with marine invertebrates, the culture media of a sponge-associated bacterial strain of Pseudomonas aeruginosa was found to contain metabolites which inhibit the growth of several Gram-positive microorganisms. A series of diketopiperazines (1-6) including a new natural product (6) and two known phenazine alkaloid antibiotics (7 and 8) were isolated from the culture broth of this bacterium.

Metabolites from an Antarctic Sponge-Associated Bacterium, Pseudomonas aeruginosa

Background Introduction to the Chemical Ecology of Marine Natural Products, M.K. Harper, T.S. Bugni, B.R. Copp, R.D. James, B.S. Lindsay, A.D. Richardson, P.C. Schnabel, D. Tasdemir, R.M. VanWagoner, S.M. Verbitski, and C.M. Ireland Ecological Perspectives on Marine Natural Product Biosynthesis, M.J. Garson Marine Natural Products Chemistry as Evolutionary Narrative, G. Cimino and M.T. Ghiselin Organismal Patterns in Marine Chemical Ecology Chemical Ecology of Mobile Marine Invertebrates: Predators and Prey, Allies and Competitors, J.J. Stachowicz The Chemical Ecology of Invertebrate Meroplankton and Holoplankton, J.B. McClintock, B.J. Baker, and D.K. Steinberg Chemical Mediation of Macroalgal-Herbivore Interactions: Ecological and Evolutionary Perspectives, V.J. Paul, E. Cruz-Rivera, and R.W. Thacker Secondary Metabolites from Antarctic Marine Organisms and their Ecological Implications, C.D. Amsler, K.B. Iken, J.B. McClintock, and B.J. Baker Spatial Patterns in Macroalgal Chemical Defenses, K. Van Alstyne, M.N. Dethier, and D. Duggins Resource Allocation in Seaweeds and Marine Invertebrates, G. Cronin Chemical Mediation of Surface Colonization, P.D. Steinberg, R. de Nys, S. Kjelleberg Cellular and Physiological Patterns in Marine Chemical Ecology Effects of Secondary Metabolites on Digestion in Marine Herbivores, N.M. Targett and T.M. Arnold Chemotaxis and Chemokinesis in Marine Bacteria and Algae, C.D. Amsler and K.B. Iken Natural Chemical Cues for Settlement and Metamorphosis of Marine-Invertebrate Larvae, M.G. Hadfield and V.J. Paul Contributions of Marine Chemical Ecology to Chemosensory Neurobiology, H.G. Trapido-Rosenthal Chemical Defenses of Marine Organisms Against Solar Radiation Exposure: UV-Absorbing Mycosporine-Like Amino Acids and Scytonemin, D. Karentz Applied Marine Chemical Ecology Marine Chemical Ecology: Applications in Marine Biomedical Prospecting, S.H. Sennett Natural Product Antifoulants and Coatings Development, D. Rittschof Metabolites of Free-Living, Commensal, and Symbiotic Benthic Marine Microorganisms, V.S. Bernan

Marine Chemical Ecology

Sponges are important components of marine benthic communities of Antarctica. Numbers of species are high, within the lower range for tropical latitudes, similar to those in the Arctic, and comparable or higher than those of temperate marine environments. Many have circumpolar distributions and in some habitats hexactinellids dominate benthic biomass. Antarctic sponge assemblages contribute considerable structural heterogeneity for colonizing epibionts. They also represent a significant source of nutrients to prospective predators, including a suite of spongivorous sea stars whose selective foraging behaviors have important ramifications upon community structure. The highly seasonal plankton blooms that typify the Antarctic continental shelf are paradoxical when considering the planktivorous diets of sponges. Throughout much of the year Antarctic sponges must either exploit alternate sources of nutrition such as dissolved organic carbon or be physiologically adapted to withstand resource constraints. In contrast to predictions that global patterns of predation should select for an inverse correlation between latitude and chemical defenses in marine sponges, such defenses are not uncommon in Antarctic sponges. Some species sequester their defensive metabolites in the outermost layers where they are optimally effective against sea star predation. Secondary metabolites have also been shown to short-circuit molting in sponge-feeding amphipods and prevent fouling by diatoms. Coloration in Antarctic sponges may be the result of relict pigments originally selected for aposematism or UV screens yet conserved because of their defensive properties. This hypothesis is supported by the bioactive properties of pigments examined to date in a suite of common Antarctic sponges.

/pdf/ecology-of-antarctic-marine-sponges-an-overview-3n3bn7e08e.pdf

Ecology of Antarctic Marine Sponges: An Overview

Cold-water marine natural products

Palmerolide A, a 20-membered macrocyclic polyketide bearing carbamate and vinyl amide functionality, was isolated from the tunicate Synoicum adareanum collected from the vicinity of Palmer Station on the Antarctic Peninsula. Palmerolide A displays potent and selective cytotoxicity toward melanoma (UACC-66 LC50 = 0.018 muM) and appears to operate via inhibition (IC50 = 2 nM) of V-ATPase.

Bill J. Baker

Papers

Metabolites from an Antarctic Sponge-Associated Bacterium, Pseudomonas aeruginosa

Marine Chemical Ecology

Ecology of Antarctic Marine Sponges: An Overview

Cold-water marine natural products

Palmerolide A, a Cytotoxic Macrolide from the Antarctic Tunicate Synoicum adareanum