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Differential Gene Expression in Heterosigma akashiwo in Response to
Model Flue Gas:Where Does the Carbon Go?
8th Annual Algae Biomass SummitAlgal Strain Development
October 2, 2014
Jennifer J. Stewart, Ph.D.Scientist, NSF SEES Fellow
R83-3221
Koonin et al. (2010) Genome Biology 11:209
What is a Raphidophyte?
Hara & Chihara 1987
3
Heterosigma akashiwo Raphidophyte Metabolizes NO gas Optimum growth
maintained over a wide range of salinity (10-30 psu) and temperature (16-30°C)
Survives nutrient limitation and high light stress
Exhibits no strong preference for nitrogen source
(NO3- , NO2
-, NH4+)Photos by Elif Demir-Hilton and Kirk Czymmek
Jennifer J. Stewart, Ph.D.Scientist, NSF SEES Fellow
Theoretical Mechanism of NR2-2/2HbN
Dual NO dioxygenase and Nitrate Reductase Activities
5 e- when fully reduced: 2 e- accepted by FAD, 1e- by heme-Fe, and 2e- by Mo-MPT
Univalent reduction of both heme-Fe centers possible
Nitrate captured(Stewart & Coyne 2011)
Jennifer J. Stewart, Ph.D.Scientist, NSF SEES Fellow
5
Air 10.5mM Flue Gas 12.4 mM
12% CO2, 150 ppm NO, N2 balance
Heterosigma akashiwo on a Model Flue Gas
Jennifer J. Stewart, Ph.D.Scientist, NSF SEES Fellow
_x0003_Air _x0008_Flue Gas0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Carbohydrate LipidProtein
Carb Lipid Protein0
1
2
3
4
5
6
7
8
9 Air Flue Gas
Pro
du
cti
vit
y (
gra
ms
m-2
da
y-1
)
Compositional Breakdown-Per Cell Basis
6
1 3 5 7 9 11 13 15 17
-10
-8
-6
-4
-2
0
2
4
6
8
10
-log(p-value)
log
2 (
fold
ch
an
ge
)
1641 Transcripts Were Significantly Differentially Expressed
524 Received KEGG Orthology (KO) Identifiers
274 Received Enzyme Commission (EC) Numbers
149 Mapped to KEGG Reference Pathways
Global Gene Expression Analysis
7
Metabolic Overview of Differentially Expressed Genes
8
Photosynthesis
Carbohydrate
Carbohydrate
TCA
Lipid Syn
N-Metabolism
AA
Isoprenoids
Abiotic Stress
Redox
Nucleotides
RNA Processing
DNA Synthesis
Protein SynthesisSignaling
Cell Cycle
Transporters
Unknowns
Metabolic Overview of Differentially Expressed Genes
9
For NR, Only NR2 sequences were Found to be Differentially Expressed The Highest Up-regulated Transporter Genes were Phosphate Transporters Flue Gas is a Significant Source of Nitrogen for Protein Synthesis
Nitrogen Uptake and Utilization
10
C14:0
C15:0
C15:1
C16:0
C16:1
C16:1
C17:0
C17:1
C18:0
C18:1
C18:2n
6
C18:3n
3C18
:4
C20:1n
9
C20:5n
3
C22:1n
9C22
:2
C22:6n
30
2
4
6
8
10
12
14
16
18Air Flue Gas
FA
ME
(p
g/ce
ll)Fatty Acid Biosynthesis
Increase in FAs involved in plastid membrane composition
11
Fatty Acid Biosynthesis
12
Carbonate Chemistry
13
CO2 Fixation During Growth on Model Flue Gas
a-D-Glucose-6P
b-D-Glucose-6P b-D-Fructose-6P
b-D-Fructose-1,6P2
Glyceraldehyde-3PGlyceraone-P
Glycerate-1,3P2
Glycerate-3P
Glycerate-2P
Phosphoenolpyruvate Pyruvate
Carbon Fixation
AA Synthesis Fatty Acid Synthesis
Up-Regulation Seen Throughout the
Glycolysis Pathway
_x0003_Air _x0008_Flue Gas0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Carbohydrate LipidProtein
Heterosig
ma aka
shiw
o
Nannoch
loropsis
sp.
0%
20%
40%
60%
80%
100%
Carbohydrate LipidProtein
Pathway for Storage Carbohydrates?12%CO2 + 150 ppm NO 2%CO2 – Day 5 Batch Growth
Pathway for Storage Carbohydrates?
16
Green algae = StarchDiatoms = Chrysolaminarin
Jennifer J. Stewart, Ph.D.Scientist, NSF SEES Fellow
17
Glycolytic and Glucan Biosynthesis in the Diatom Phaeodactylum tricornutum
Chauton et al. (2013) Plant Physiology 161:1034
18
All Roads Lead to b-D-Fructose-6P
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Storage Carbohydrate metabolism of Ectocarpus siliculosus. Michel et al. (2010) New Phytologist 188:67
Dittami et al. (2011) Plant Signaling & Behavior 6:8
Fate of b-D-Fructose-6P in Brown Macro-Algae
Acknowledgements
20
R83-3221 R83-3221
• UD: Kathy Coyne, Mark Warner, & Tom Hanson • SU: Katherine Miller• ASU: John McGowen, Tom Dempster, Hank Gerken, and
Crew• Lab Members: Colleen Bianco, Chris Main, Kaytee P.,
Josee Nina Bouchard• DNREC Division of Air Quality: Ali Mirzakhalili & Mark
Lutrzykowski• The following funding sources:
Jennifer J. Stewart, Ph.D.Scientist, NSF SEES Fellow
