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PHOTOBIOLOGY. Part 3: Photoprotection. Part 3: Photoprotection. Nadine Schubert Instituto de Ciencias del Mar y Limnología de la UNAM Unidad de Sistemas Arrecifales, Puerto Morelos, México. Photorespiration Water-water cycle Cyclic e - - transport. Energy dissipation.
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PHOTOBIOLOGY Part 3: Photoprotection Part 3: Photoprotection Nadine Schubert Instituto de Ciencias del Mar y Limnología de la UNAM Unidad de Sistemas Arrecifales, Puerto Morelos, México
Photorespiration Water-water cycle Cyclic e-- transport Energy dissipation LIGHT ABSORPTION UTILIZATION OF ABSORBED LIGHT ENERGY LIGHT Adjustment of antenna size State transition Light capture Thermal dissipation Xanthophyll cycle Photochemistry CO2 fixation Production of Oxygen Radicals Antioxidant systems Photodamage Repair and de novo synthesis Net photodamage
LIGHT ABSORPTION UTILIZATION OF ABSORBED LIGHT ENERGY Excess energy Fv/Fm Photosynthesis Photoprotection Fv/Fm O2 Photoinactivation/Photodamage Irradiance
Violaxanthin Cycle Yamamoto et al., (1962) XANTHOPHYLL CYCLE
Protective pigment Energy dissipater Accessorypigment Energy collector Violaxantina Zeaxantina S2 Energía Clorofila a S1 S1 Qy Calor S0 PHOTOPROTECTION BY CAROTENOIDS Violaxanthin Zeaxanthin Energy Chlorophyll a Heat Antheraxanthin, Lutein
NON-PHOTOCHEMICAL QUENCHING PS = 0 NPQ = 0 NPQ = (Fm-Fm’)/Fm’ PS = 0 1 NPQ 0 1 PS 0 1 NPQ 0 PS = 1 NPQ = 0
Relationship between ZEA-content and Fv/Fm and NPQ Macrocystis pyrifera Dictyota dichotoma Uhrmacher et al. (1995) Garcia-Mendoza & Colombo-Pallotta (2007) Open symbols = light exposure to 150 mol m-2 s-1 Closed symbols = light exposure to 500 mol m-2 s-1
Müller et al. (2001) NON-PHOTOCHEMICAL QUENCHING
PHOTODAMAGE ATP ADP + Pi NADPH NADP + H+ 2H+ Fd 1O2 ATPase PQH2 PSII LHCII Cyt bf PSI LHCI PQ 1O2 PC H+ 2H2O O2+ 4H+ 2H+
3P680* P680 3O2 1O2* 3Car* 1Car HEAT PHOTODAMAGE PSII LHCII 1O2 2H2O O2+ 4H+ Carotenoids: -carotene - reaction center
3Chl* Chl 3O2 1O2* 3Car* 3Car* 1Car 1Car HEAT HEAT 1O2 PHOTODAMAGE PSII LHCII 2H2O O2+ 4H+ Carotenoids: zeaxanthin, lutein - PSII antennae
CYANOABACTERIA RED ALGAE GREEN ALGAE, HIGHER PLANTS BUT CAREFUL…
BUT CAREFUL… Determination of Fm is very difficult in red algae due to phycobilisome movement application of far-red pulse before measurement to ensure that PSII antenna is associated to PSII
BUT CAREFUL… Campbellet al. (1998)