Part 3: Photoprotection
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Transcript of Part 3: Photoprotection
1Nadine SchubertInstituto de Ciencias del Mar y Limnología de la UNAM Unidad de Sistemas Arrecifales, Puerto Morelos, México
Part 3:Part 3: Photoprotection Photoprotection
PHOTOBIOLOGY PHOTOBIOLOGY
Part 3:Part 3: Photoprotection Photoprotection
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LIGHT ABSORPTION UTILIZATION OF ABSORBED LIGHT ENERGY
LIGHT
Light capture
Photochemistry
Production of Oxygen Radicals
Net photodamage
Photodamage
Repair and de novo synthesis
Antioxidant systems
Thermal dissipation Xanthophyll cycle
Adjustment of antenna size State transition
CO2 fixation PhotorespirationWater-water cycleCyclic e-- transportEnergy dissipation
3Irradiance
Pho
tosy
nthe
sis
Photoprotection
Photoinactivation/Photodamage
Excess energy
Fv/Fm
Fv/Fm O2
LIGHT ABSORPTION UTILIZATION OF ABSORBED LIGHT ENERGY
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XANTHOPHYLL CYCLE
5Antheraxanthin, Lutein
Violaxanthin Zeaxanthin
PHOTOPROTECTION BY CAROTENOIDS
Chlorophyll a
Heat
En
erg
y
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PS = 0NPQ = 0
PS = 1NPQ = 0
1 PS 01 NPQ 0
PS = 01 NPQ 0
NON-PHOTOCHEMICAL QUENCHING
NPQ = (Fm-Fm’)/Fm’
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Uhrmacher et al. (1995)
Dictyota dichotoma
Open symbols = light exposure to 150 mol m-2 s-1
Closed symbols = light exposure to 500 mol m-2 s-1
Relationship between ZEA-content and Fv/Fm and NPQ
Garcia-Mendoza & Colombo-Pallotta (2007)
Macrocystis pyrifera
8Müller et al. (2001)
NON-PHOTOCHEMICAL QUENCHING
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PSIILHCII Cyt bf PSI LHCI
2H2O O2+ 4H+
2H+
PQ
PQH2
2H+
PC
Fd
NADP + H+ NADPH
H+
ATPase
ADP + Pi ATP
1O2
1O2
PHOTODAMAGE
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PHOTODAMAGE
1Car
3Car*
HEAT
Carotenoids: -carotene- reaction center
3P680*
P680
3O2
1O2*
PSIILHCII
2H2O O2+ 4H+
1O2
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PHOTODAMAGE
PSIILHCII
2H2O O2+ 4H+
1O2
3Chl*
Chl
3O2
1O2*1Car
3Car*
HEAT Carotenoids: zeaxanthin, lutein
- PSII antennae
1Car
3Car*
HEAT
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BUT CAREFUL…
CYANOABACTERIA
130
10
20
30
40
50
60
70
80
90
100
P.perforata C.volans P.pacifica C.officinalis
Fm
(%
de
F m e
n f
ar-r
ed)
far-red
oscuridad
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
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BUT CAREFUL…
Campbellet al. (1998)