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 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
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
Average expression
Expression
ratio ratio
1
1,5
Stress genes
Stress
Antioxidative
enzymes
0,5 1
0,5
0
-0,5
0
C
2x
0.5x
HiT
HiLi
HiNS LoNS
-0,5
Clustering of HSPs
C
2x
0.5x
HiT
HiLi
HiNS LoNS
Glutathione S-transferases in red and brown algae
-seaweeds contain new classes
Protein production
M
kDa
1
2
3
4
5
150 –
100 –
75 –
50 –
37 –
25 –
LdGST54
20 –
12
10
8
6
4
2
0
-2
66 kDa
Induction by
H2O2, oxylipins,
herbicides & metals
A new class
GSTs
3
4
15
200 kDa
Source
ESTs
ESTs
ESTs +
genome
Absorbance at 280 nm (mAU)
Species
Chondrus
Laminaria
Ectocarpus
Phylogeny
29 kDa
The GST, found in all organisms, are
best known for their major roles in
detoxification
Roles of oxylipins in macroalgae
-mechanisms and signaling
Laminaria digitata
Chondrus crispus
Abiotic and biotic stress (copper, endophytic alga)
Genomic resources
(ESTs genomes)
Characterisation of enzymes
Algal tissues
Transcriptomic profiling
Integration of results
Metabolite profiling
Production of plant-like (C18)
and animal-like (C20)
oxygenated PUFA derivatives
+ new molecules?
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
Effects of heavy metals on brown algal physiology
-the example copper and Ectocarpus
0 mg
500
mg
Toxicology
Proteomics
Transcriptomics
- Increased expression of HSP, GST, MSR, TRX
Lipidomics
- Production of oxylipins
CO1
100
%
32.18
39.78
0
C332
100
CO1
100
33.99
%
%
and free fatty acids
0
300241
0
2.56
27.14
34.69
33.11
32.18
100
C332
40.08
45.29
39.78
34.81
100
%
24h 300
Cu2+ µg/L
2.50
22.75 25.15
%
22.05
27.20
20.00
33.11
27.14 30.00
0
2.56
10.00
29.72 34.40
33.99
40.37
38.79
34.69
40.08
40.00
45.75
45.29
50.03
50.00
54.59
60.00
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,
500 mg
methionine sulfoxide reductase,
thioredoxin
Lipidomics
- Biosynthesis of oxylipins
CO1
100
and free fatty acids release
%
32.18
39.78
0
C332
100
CO1
100
33.99
%
%
0
300241
0
2.56
27.14
34.69
33.11
32.18
100
C332
40.08
45.29
39.78
34.81
100
24h 300 Cu2+ µg/L
%
2.50
22.75 25.15
%
22.05
27.20
20.00
33.11
27.14 30.00
0
2.56
10.00
29.72 34.40
33.99
40.37
38.79
34.69
40.08
40.00
45.75
45.29
50.03
50.00
54.59
60.00
Osmotic stress in Ectocarpus siliculosus
-an integrative approach
Ectocarpus
Mutagenesis
High
salinity
Low
salinity
Screening:
photosynthesis
& survival
Sensitive
and
resistant
mutants
OSMOTIC S T R E S S
Sequence data
(ESTs, genome)
Transcriptomics: microarray
Physiology &
metabolic profiling
Candidate genes
Intracellular osmolarity
Targeted
studies
Integrative approach
[Na+] and [K+]
Osmolytes
Amino acids
Understanding of osmotic
stress responses
Pigments
Photosynthesis
Defense reactions in brown algae
-Laminaria produces an oxidative burst after elicitation
Grazers, microbes
endophyte attack
G-G-G-G-GCell wall damage
Alginate degradation
Control
H2O2 release
300
n (H2O2)/FW nmol/g
250
Control
100 µg/mL GG
200
150
100
50
Elicited
0
0
10
20
30
Time (min)
40
50
Defense reactions in brown algae
-halogen metabolism in Laminaria
Hours after elicitation
3
6
12
4
X- + H2O2
2
HPO
2n variation
0
XHO
-2
-4
-6
-8
BPO1
BPO3
IPO1
IPO3
Reactive halogens
Halogenated compounds
Haloperoxidases as anti-oxidant enzymes?
Haloperoxidases provides potential antimicrobial compounds
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