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Chemical ecology of tropical algae: Part I

Chemical ecology of tropical algae: Part I. Bernardo A.P. da Gama Universidade Federal Fluminense Niterói – Rio de Janeiro - Brazil. Outline. The tropical marine environment What is seaweed chemical ecology? What are secondary metabolites? How are they biosynthesized?

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Chemical ecology of tropical algae: Part I

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  1. Chemical ecology of tropical algae:Part I Bernardo A.P. da Gama Universidade Federal Fluminense Niterói – Rio de Janeiro - Brazil

  2. Outline • The tropical marine environment • What is seaweed chemical ecology? • What are secondary metabolites? • How are they biosynthesized? • Why are they biosynthesized? • Ecological roles of macroalgal metabolites • Resource allocation models • Defenses against herbivores • Defenses against epibionts caulerpenyne

  3. Part I • The tropical marine environment • What is seaweed chemical ecology? • What are secondary metabolites? • How are they biosynthesized? • Why are they biosynthesized? • Ecological roles of macroalgal metabolites • Resource allocation models • Defenses against herbivores • Defenses against epibionts caulerpenyne

  4. References • Few books, majority of knowledge is hot out of the press! • Consequence of the novelty of this expanding field Ecological roles of marine natural products Edited by Valerie J. Paul Springer 2008 CRC Press 2001 Comstock Publishing 1992

  5. The tropical marine environment • Conspicuous and diverse coral reefs are NOT the only tropical ecosystems! • Seagrass beds, rocky shores, mangrove forests – equally important

  6. The tropical marine environment • How to define it? • Latitude: between 23o27’ N and S • SST: sea surface temperatures – more accurate indication

  7. The tropical marine environment Consider this: • Macroalgae are restricted to the euphotic zone • Present boundaries are set by SS isotherms (20oC-winter isotherms) • Presence of hard substrata is a condition for most macroalgae • Present distribution results from migration & displacement of coastlines along geological times (continental drift)

  8. The tropical marine environment • Add to this the recent (~500 y.a.) human-mediated amplification of distributions – bioinvasions • Further human-mediated changes are to be expected if global climatic changes really affect global oceanic currents! Sea Surface Temperature, MODIS satellite data, NASA, GSFC

  9. What is algal chemical ecology? • Science that studies any type of ecological interaction involving marine algae mediated by chemical compounds • E.g.: herbivory, competition, gamete attraction, symbiosis, epibiosis, settlement, etc. capisterone A, R = COCH3 capisterone B, R = H

  10. What are secondary metabolites? • Also called natural products • Not involved in primary cell functions • Thus called secondary metabolites • Specific or mixed biosynthetic pathways • Many are group- or even species-specific Please read Faulkner yearly reviews and later Blunt et al. entitled “Marine natural products” In Natural Product Reports phlorotannins

  11. How are they biosynthesized? Maschek & Baker (2008)

  12. Isoprenoids • Mevalonate-dependent & independent quinones terpenes carotenoids steroids

  13. Acetogenins Polyketides polyphenolics (phlorotannins) fatty acids prostaglandins

  14. Amino acids alkaloids peptides

  15. Shikimate pathway flavonoids coumarins cinnamic acid derivatives (seagrasses)

  16. Nucleic acids nucleotid base modified nucleic acid

  17. Carbohydrates sugar polysaccharide

  18. Why are they biosynthesized? • If you discover, please let me know! • Some claim they are just “metabolic waste products” • Some are clearly involved in basic, non-ecological roles (e.g., phlorotannins) • Makes no sense to invest in genetic information, enzymes and precursors to synthesize them if they play no function! • Chemical communication and warfare Williams DH (1989) Why are secondary metabolites (natural products) biosynthesized? J Nat Prod

  19. Intraspecific molecular interactions SEXUAL AUTOTOXINS ALARM AUTOINHIBITORS TRACK / CUE GROUPING PHEROMONES TERRITORIAL

  20. Interspecific molecular interactions SYMBIONT LOCALIZATION KAIROMONES PREY LOCALIZATION ALARM / CUE benefit the receiver of the chemical message

  21. Interspecific molecular interactions (II) ATTRACTION REPELLENT DEFENSE ANTIBIOTIC ALLOMONES COMPETITION POISON benefit the sender of the message

  22. anti- Fouling Pathogens Alellopathy Energy source feromones sexual UV protection Consumption Bacteria Algae Fungi Invertebrates & fish simbiosis

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