Presentation is loading. Please wait.

Presentation is loading. Please wait.

Ectocarpus siliculosus

Similar presentations


Presentation on theme: "Ectocarpus siliculosus"— Presentation transcript:

1 Ectocarpus siliculosus
Filamentous, cosmopolitan brown alga – mostly from temperate seas One of the best-studied seaweeds The first fully-sequenced multicellular alga – ongoing genome annotation > 300 fully-characterized strains in public-domain culture collections (CCAP, KU-MACC)

2 So what about Ectocarpus?
Ectocarpus accumulates iodine, but at much lower levels than Laminaria (data from Roscoff & Vernaison) Genome annotation has revealed the presence of one vanadium haloperoxidase gene X-ray absorption spectroscopy using synchrotron radiation (XAS) on Ectocarpus

3 Iodine K-edge XAS of Ectocarpus siliculosus
Like Laminaria, Ectocarpus accumulates iodine as iodide!

4 Iodine metabolism in Ectocarpus
At present probably more questions than answers! Does iodide have an apoplastic antioxidant function in Ectocarpus? What does the genome tell us about antioxidant systems? Does Ectocarpus produce iodinated / halogenated metabolites, are there iodo-/halocarbons? Ongoing work - NERC SOLAS grant to Lucy J. Carpenter (York) and FCK

5 Outlook and open questions
Mechanism of cell wall / apoplastic accumulation, storage of iodide? How does the mobilization upon oxidative stress work? Giant kelp / Macrocystis?

6 So what about Greece and the Mediterranean Sea?
Very little is known about halogen fluxes in Mediterranean coastal systems! In particular, molecular iodine and halocarbon emissions from Mediterranean seaweeds are seriously understudied

7 So what about Greece and the Mediterranean Sea?
Some tropical/Mediterranean seaweeds are known to be strong iodine accumulators: Asparagopsis taxiformis (Rhodophyta) Other candidates (known for strong halogen metabolism, albeit not iodine accumulation): Rhodophyta - Gracilaria sp., Ceramium sp., Dasya sp., Laurencia sp. Phaeophyta – Ectocarpales, Fucales (Sargassum sp.) Deep-water kelp (Laminariales)?

8 Deep-water kelp in the Mediterranean Sea
Laminaria rodriguezii, mainly known from western / central Mediterranean Not known from Greece so far – lack of exploration of relevant depth range (> 50 m)

9 Deep-water kelp forests in the tropics: An analogy to the Mediterranean Sea?
Graham et al., 2007: Deep-water kelp refugia as potential hotspots of tropical marine diversity and productivity.- PNAS 104 (42),

10 Deep-water kelp in the Mediterranean Sea
What are the implications for marine and atmospheric halogen chemistry in the region?

11 A place where you can smell the tide level…
Roscoff, Brittany, France

12 Acknowledgements -- Peter M.H. Kroneck (University of Konstanz, Germany) -- Sonja Woitsch, Markus Weiller (dto.) -- Lucy J. Carpenter and Carl Palmer (University of York, UK) -- Gordon McFiggans (University of Manchester, UK) -- Philippe Potin (CNRS, Roscoff, France) - Martin Feiters (University of Nijmegen, The Netherlands) - Wolfram Meyer-Klaucke and Gerd Wellenreuther (European Molecular Biology Laboratory, Hamburg, Germany) - Eva M. Boneberg (Biotechnologie Institut Thurgau, Switzerland, formerly at University of Konstanz) - Alison Butler (University of California, Santa Barbara, USA) - George Luther & Tim Waite (University of Delaware, Lewes, USA) - Rafael Abela & Daniel Grolimund (Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland)

13 Thank you. Dunstaffnage Marine Laboratory,
Oban, Argyll / West Highlands, Scotland

14 Reserve slides follow

15 What makes iodide a suitable antioxidant?
Thermodynamics Cl- Br- I- One-electron transfer per X- GR (kJ mol-1) X- + 3O2  [X] O2• - 247.97 200.7 143.76 X- + OH• (g)  [X] + OH- 49.21 1.93 -55.0 X- + OH•(aq)  [X] + OH 67.54 20.26 -36.66 X- + 1O2  [X] + O2• - 152.45 105.17 48.24 X- + H2O2  [X] + OH• + OH- 235.42 188.15 131.22 X- + H+ + HO2 •  [X] + H2O2 93.59 46.31 -10.61 X- + O3  [X] + O3• - 135.08 87.80 30.87

16 What makes iodide a suitable antioxidant?
Thermodynamics Cl- Br- I- Two-electron transfer per X- GR (kJ mol-1) 2 X- + H+ + O3  X2 + O2 + OH- - 57.9 -112.5 X- + H+ + O3  HOX + O2 -111.8 -141.4 -210.8 X- + H+ + 1O2 + H2O  HOX + H2O2 62.48 32.88 -36.43 X- + 2H+ + 1O2  X2 + H2O2 96.66 42.06 -62.76 X- + H2O2  HOX + OH- 28.21 -1.39 -70.81 X- + 2 H+ + H2O2  X2 + 2 H2O -77.66

17 What makes iodide a suitable antioxidant?
Kinetics Compound k12 (M-1 s-1) O3 reactions with I x 109 Br x 102 Cl- < 3 x 10-3 Ascorbate x 107 Glutathione x 106 Singlet oxygen (1O2) reactions with I x (aprotic solvents) 8.7 x 105 (pH ~ 7) Br x 103 Cl x 103 Ascorbate x 106 Glutathione x (in D2O, 310 K, pD = 7.4)

18 What makes iodide a suitable antioxidant?
Kinetics Compound k12 (M-1 s-1) OH radical (OH) reactions with I x 1010 Ascorbate x 1010 Glutathione x (pH = 5.5) Dimethyl sulfoniopropionate 3 x 108 Dimethyl sulfide x 1010 Dimethyl sulfoxide 6.6 x 109 Superoxide (O2-) reactions with I x (no data available for I-) Ascorbate x (pH= 7.4) Glutathione x (pH= 7.8)

19 What makes iodide a suitable antioxidant?
Kinetics Compound k12 (M-1 s-1) Hydrogen peroxide (H2O2) reactions with I Br x 10-5 Cl x 10-7 Ascorbate 2 x 100 Glutathione 2 – 20 x 100 Glutathione peroxidase 6 x 107


Download ppt "Ectocarpus siliculosus"

Similar presentations


Ads by Google