Transcriptomic responses of Emiliania huxleyi to Ocean Acidification Sebastian D. Rokitta, Uwe John and Björn Rost
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