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Oxidative stress in seaweeds

Oxidative stress in seaweeds. Jonas COLL ÉN UMR 7139 –Catherine BOYEN Végétaux marins et biomolécules Station Biologique de Roscoff. Intertidal seaweeds and oxidative stress. The intertidal is harsh, dynamic, and non-predictable → A high stress environment

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Oxidative stress in seaweeds

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  1. Oxidative stress in seaweeds Jonas COLLÉN UMR 7139 –Catherine BOYENVégétaux marins et biomolécules Station Biologique de Roscoff

  2. Intertidal seaweeds and oxidative stress • The intertidal is harsh, dynamic, and non-predictable→ A high stress environment • Seawater can be depleted of CO2 and supersaturated with O2→Potential for high ROS production during photosynthesis • Seawater contains high concentrations of halides→Formation of reactive halogens, e.g. Br & I • Seawater can be both a source and a sink of ROS • Seaweeds lack roots, xylem/phloem, cuticle→High rate of desiccation and local phenomena • Reproductive structures are often photosynthetically active

  3. Three principal models Ectocarpus siliculosus Laminaria digitata Chondrus crispus

  4. Seaweeds and oxidative stress-principal present research areas • Stress physiology of Chondrus crispus • Glutathione S-transferases in red and brown algae • Roles of oxylipins in macroalgae • Osmotic stress in Ectocarpus siliculosus • Effects of heavy metals on brown algal physiology • Defense reactions in brown algae

  5. Clustering of HSPs Stress physiology of Chondrus crispus -a transcriptomic approach Stress genes

  6. Glutathione S-transferases in red and brown algae-seaweeds contain new classes Phylogeny A new class Protein production The GST, found in all organisms, are best known for their major roles in detoxification Species Source GSTsChondrus ESTs 3 Laminaria ESTs 4Ectocarpus ESTs + 15 genome Induction byH2O2, oxylipins, herbicides & metals

  7. Roles of oxylipins in macroalgae -mechanisms and signaling Laminaria digitata Chondrus crispus Abiotic and biotic stress (copper, endophytic alga) Genomic resources (ESTs genomes) Algal tissues Metabolite profiling Transcriptomic profiling Characterisation of enzymes Production of plant-like (C18) and animal-like (C20) oxygenated PUFA derivatives + new molecules? Integration of results Expected results - Verification of known oxylipins metabolic pathways - Identification of new enzymatic activities/oxylipins pathways - Regulation of the oxylipin pathways - Evolution of lipid signalling mechanisms in eukaryotes

  8. 0 mg 500 mg Effects of heavy metals on brown algal physiology-the example copper and Ectocarpus • Toxicology • Proteomics • Transcriptomics- Increased expression of HSP, GST, MSR, TRX • Lipidomics- Production of oxylipinsand free fatty acids 24h 300 Cu2+ µg/L

  9. Effects of heavy metals on brown algal physiology-the example copper and Ectocarpus 0 mg • Toxicology • Proteomics: 2D analysis • Transcriptomics- Increased expression of HSP, GST, methionine sulfoxide reductase, thioredoxin • Lipidomics- Biosynthesis of oxylipinsand free fatty acids release 500 mg 24h 300 Cu2+ µg/L

  10. Osmotic stress in Ectocarpus siliculosus-an integrative approach Ectocarpus High salinity Screening: photosynthesis& survival Sensitive and resistant mutants Mutagenesis Low salinity OSMOTIC S T R E S S Sequence data (ESTs, genome) Transcriptomics: microarray Physiology & metabolic profiling Candidate genes Intracellular osmolarity [Na+] and [K+] Targeted studies Integrative approach Osmolytes Amino acids Pigments Understanding of osmotic stress responses Photosynthesis

  11. Control Elicited Defense reactions in brown algae-Laminaria produces an oxidative burst after elicitation Grazers, microbes endophyte attack G-G-G-G-G- Cell wall damage Alginate degradation H2O2 release n (H2O2)/FW nmol/g Time (min)

  12. Defense reactions in brown algae-halogen metabolism in Laminaria Hours after elicitation 3 6 12 X- + H2O2 HPO XHO 2n variation Reactive halogens Halogenated compounds Haloperoxidases as anti-oxidant enzymes? Haloperoxidases provides potential antimicrobial compounds

  13. Perspectives • Genome of Ectocarpus • Genome sequenced (11x coverage) and assembled. • Genome of Chondrus • Pilot genome project started, 1.3x sequenced. New more powerful tools From gene and expression to structure and function

  14. The people Functional genomicsCatherine BOYENJonas COLLÉNSimon DITTAMIP-O DE FRANCOCécile HERVÉSylvie ROUSVOALThierry TONON Defense and signaling in marine algaePhilippe POTINAudrey COSSELudovic DELAGE Catherine LEBLANCAndres RITTERJean-Pierre SALAÜNFrançois THOMAS

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