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Transcriptomic responsesof Emiliania huxleyi
to Ocean Acidification
Sebastian D. Rokitta, Uwe John and Björn Rost
Ocean Acidifcation
CO2
pH
DIC
Year
[CO32-]
300
250
150
100
50
0
200
1850 1900 21001950 20502000
pHSWS
7.8
8.2
8.1
8.0
7.9
2400
1600
1200
800
400
2000
0
[DIC][μmol kg-1]
CO32-
[CO2]
35
30
20
15
5
0
25
10
[μmol kg-1]
After Wolf-Gladrow et al. (1999)
Photo: NASA, PML
Coccolithophores
Biological carbon pumps
OA-responses in E. huxleyi
Modified from Hoppe et al. (2011)
Energization?
The matrix approach
Light vs. pCO2
50 μmol photons m-2 s-1
300 μmol photons m-2 s-1
380 μatm 1000 μatm
• Acclimation data (μ, POC, PIC)• Physiology (Ci acquisition, light reactions)• Transcriptomics (gene expression)
Phenomenology Rokitta & Rost (2012)
• PIC production drops(especially under low light!)
• POC production is boosted(especially under low light!)
• TPC production is insensitive
Physiology Rokitta & Rost (2012)
• More POC despite less pigmentation and O2 evolution
Improved energy efficiency under OA
Gene expression?
Transcriptomics
Low-lightacclimation
1172 ↑861 ↓
High-lightacclimation
1082↑814 ↓
OA responsive genes
Low-lightspecific
447 ↑236 ↓
High-lightspecific
357 ↑189 ↓
725 ↑625 ↓
CoreOA-response
Transcriptomics
# of genes; s ign denotes regulat ion (+ ↑ ; - ↓ )
Carbon metabolism
Light physiology
Signalling
Ion fluxes
CoreOA-response
LL specificOA-response
HL specificOA-response
-40 -20 0 20 40 -40 -20 0 20 40 -40 -20 0 20 40
Organellar shuttling ↑Pentose phosphate pathway ↑Glycolysis ↓Fatty Acid & Glucan anabolism↑
Energy dissipation ↑
Lipid and IP3 signaling ↑
Membrane potentials ↑
Regulation of C fluxes ↑
Energy dissipation ↑
Transcriptomics
OA re-wires carbon fluxes
NADPH NADH
OA affects the redox hub
Carbonmetabolism
Trx
XC
Asc
GSH
Chloro-plast
EMS
NADP/NADPH
NAD/NADH
...
Mitochon-drium
Conclusions
• OA causes a shunting of carbon fromcalcification towards biomass production
• OA-Responses are modulated by energyavailability and typically attenuated by high light
• OA affects cellular signaling and the redox hub and thereby re-wires carbon flux networks
