Oxidative stress in seaweeds Jonas COLLÉN 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 Seawater can be depleted of CO 2 and supersaturated with O 2 → 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

Three principal models Ectocarpus siliculosus Laminaria digitata Chondrus crispus

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

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

Induction by H 2 O 2, oxylipins, herbicides & metals Glutathione S-transferases in red and brown algae -seaweeds contain new classes Phylogeny A new class The GST, found in all organisms, are best known for their major roles in detoxification Protein production SpeciesSource GSTs Chondrus ESTs 3 Laminaria ESTs 4 Ectocarpus ESTs + 15 genome

Laminaria digitata Chondrus crispus Abiotic and biotic stress (copper, endophytic alga) Roles of oxylipins in macroalgae -mechanisms and signaling 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 Characterisation of enzymes Transcriptomic profiling Metabolite profiling Integration of results Genomic resources (ESTs genomes) Algal tissues Production of plant-like (C18) and animal-like (C20) oxygenated PUFA derivatives + new molecules?

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 oxylipins and free fatty acids 24h 300 Cu 2+ µg/L 0  g 500  g

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

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

Defense reactions in brown algae - Laminaria produces an oxidative burst after elicitation G-G-G-G-G- Cell wall damage H 2 O 2 release Time (min) n (H2O2)/FW nmol/g Grazers, microbes endophyte attack Alginate degradation Control Elicited

Hours after elicitation 3612 Haloperoxidases as anti-oxidant enzymes? Haloperoxidases provides potential antimicrobial compounds 2 n variation X - + H 2 O 2 XHO Reactive halogens Halogenated compounds HPO Defense reactions in brown algae -halogen metabolism in Laminaria

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

The people Functional genomics Catherine BOYEN Jonas COLLÉN Simon DITTAMI P-O DE FRANCO Cécile HERVÉ Sylvie ROUSVOAL Thierry TONON Defense and signaling in marine algae Philippe POTIN Audrey COSSE Ludovic DELAGE Catherine LEBLANC Andres RITTER Jean-Pierre SALAÜN François THOMAS