Post on 15-Jul-2015
transcript
Eukaryotic metatranscriptome profiling identifies the unique responses of phytoplankton functional groups to deep water upwelling at station ALOHA
Harriet Alexander1, Monica Rouco-Molina2, Sheean Haley2, Sonya Dyhrman2
1 MIT/WHOI Joint Program in Oceanography2 Earth and Environmental Science, Lamont-Doherty Earth Observatory, Columbia University
Stochastic blooms of large phytoplankton balance NCP at Station ALOHA
Image credits: SeaWIFS Global Chlorophyll
North Pacific Subtropical Gyre
Station ALOHA
(Karl and Church, Nature Rev. Microbiol., 2014)
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Sampling at Station ALOHA coupled with bloom simulations
+ 10% DSW
700m0.2 μm filtered
S
In situ
E
Deep seawater amendment
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CTD
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6 August 24 August 2 September0.0
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168 h
Chlorophyll (mg m-3)
Start date of experiment
S1
E1
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S = In situE = Experimental
Sampling at Station ALOHA coupled with bloom simulations
0
100
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8/6 8/10 8/14 8/23 8/27 8/31 9/89/4
S1 S2
0.9
0.6
0.3
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CTD
Ch
loro
pig
me
nt
(μg
/L)
Pre
ssu
re (
db
ar)
S3
E1S1 E2S2 E3S3
What are the biogeochemical constraints on the oligotrophic large phytoplankton? What are the functional group transcriptional responses to deep seawater (DSW) upwelling?
S = In situE = Experimental
Sampling at Station ALOHA coupled with bloom simulations
E1
Sampling and processing for metatranscriptomes
S1
0
100
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8/6 8/10 8/14 8/23 8/27 8/31 9/89/4
S1 S2
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0.3
0
CTD
Ch
loro
pig
me
nt
(μg
/L)
Pre
ssu
re (
db
ar)
S3
Filter (>5μm)
Extract RNA
Poly-A selection
Sequence(Illumina 60M 100bp PE)
Map to custom reference database (MMETSP)
Pool counts by functional group
MMETSP=Marine Microbial Eukaryotic Transcriptome Sequencing Project
S1 S2 S30
20
40
60
80MMETSP
Genome
Reads mapped to reference (%)
DSW addition alters functional group composition; shift similar across replicated experiments
Dinoflagellates Diatoms Haptophytes
Little changein species composition
Significant changes in species composition
DIA HAP DIN
ENVIRONMENTAL INFORMATION
PROCESSING
ENERGY METABOLISM
CARBOHYDRATE AND LIPID
METABOLISM
NUCLEOTIDE AND AMINO ACID
METABOLISM
GENETIC INFORMATION
PROCESSING
METABOLISM
Metabolic fingerprint differs between groups
and shifts after DSW addition
DIA HAP DIN
ENVIRONMENTAL INFORMATION
PROCESSING
ENERGY METABOLISM
CARBOHYDRATE AND LIPID
METABOLISM
NUCLEOTIDE AND AMINO ACID
METABOLISM
GENETIC INFORMATION
PROCESSING
METABOLISM
Metabolic fingerprint differs between groups
and shifts after DSW addition
95% confidence intervals indicated
DIA HAP DIN
ENVIRONMENTAL INFORMATION
PROCESSING
ENERGY METABOLISM
CARBOHYDRATE AND LIPID
METABOLISM
NUCLEOTIDE AND AMINO ACID
METABOLISM
GENETIC INFORMATION
PROCESSING
METABOLISM
Metabolic fingerprint differs between groups
and shifts after DSW addition
For each gene determineSignificance Post-p > 0.95 for 2-fold change
Experiments coupled with field sampling identify metabolic response to DSW addition
Phosphate and amino acid transport
Metallic and B12 transport
Transcriptional response to DSW addition unique
Down-regulation following DSW addition
Up-regulationfollowing DSW addition
No major shifts in metabolism; most regulation
post-transcription?
Biogeochemical drivers of observed metabolic shifts
Urea transporter
Nitrate/itetransporter
Phospho-diesterase
Adenosyl-homocysteinase
Iron transporter
DIA
HAP
N P Vitamins Fe
Down in DSW
Up in DSW
No significant change
Complex co-limitation?Drivers not consistent across functional groups
Transcriptional response to DSW additionunderscores functional group traits
Diatoms “the scavengers”; r-selected
Haptophytes “the survivalists”; K-selected
Down-regulation following DSW addition
Up-regulationfollowing DSW addition
Functional group specific traits drive ecology of the system… balancing NCP
What are the biogeochemical constraints on the oligotrophic large phytoplankton?
Vary by functional group (Fe, N, P, vitamins)Possible complex co-limitation
What are the functional group transcriptional responses to deep water upwelling?
Dinoflagellates: Little/no transcriptional responseDiatoms: Broad down-regulation indicative of “scavenger”; r-selectedHaptophytes: General up-regulation indicative of “survivalist”; K-selected
Acknowledgements
o Dyhrman Lab
o Captain, crew of R/V Kilo Moana
o Science party of HOE-DYLAN
o Bethany Jenkins
Funding:o CMORE
o MMETSP/Gordon & Betty Moore Foundation
o NSF
o NDSEG
o MIT Presidential Fellowship
o MIT/WHOI Joint Program