Uptake Rates as Fundamentals of Iron Availability to
Phytoplankton
Yeala Shaked
Interuniversity Inst. for Marine Sciences, Eilat
Hebrew University, Jerusalem, Israel
GEOTRACES Synthesis Workshop Aug 1-4th 2016
Interac(onsandecosystemprocesses
! Bio-mediatedtransforma(onsofFespecia(on
! Physicaleffects(e.g.light,temperature)onphytoplanktonphysiology&ecologyandFespecia(on&fate
! Feinputs,recycling&residence(mes
! Chemical&photochemicaltransforma(onsofFe
! Foodwebinterac(ons
! Phytoplanktonphysiology,biochemistryandspeciescomposi(on
Whatdeterminesthebioavailabilityofirontophytoplankton?
ShakedandLis,2012
PathwaysandratesofFeacquisi(onbyphytoplankton
Chemicalreac(vityofFespecies&compa(bilitywithuptakesystems
FundamentalsofFeavailability
FeL, Fe’
Fe(II)
FeL
Uptakepathways&ratesChemicalspecia(onandkine(cs
Organic Inorganic
Par(cles Colloids Dissolved
Fe(III) Fe(II)
Emphasisonkine(cs-Usinguptakerateconstants(Kin)forcomparisons&extrapolaBontotheenvironment
FundamentalsofFeavailability
Lis,Shaked,Kranzler,KerenandMorel.2015.ISMEIronbioavailabilitytophytoplankton:anempiricalapproach
Syenchococcus
Trichodesmium
T.weisfloggii
T.psuedonana
P.tricornutum
E.hux
Phaeocys:s
Psuedo-nitzschia Thalassiosira
P.minimum
P.micans N.oculata
ChaetocerousT.antarc:ca
Anabaena
Phaeocys:s Psuedo-nitzschia
Thalassiosira
P.calceolata
• DophytoplanktondifferintheirabilitytoacquireFe?
• Aretherelower/upperlimitstouptakerates?
• WhichFecomplexesaremore/lessavailable?
• CanlabstudieshelpdefineFeavailabilityinnaturalenvironments?
Compiling5decadesofuptakestudies:
Syenchococcus
Trichodesmium
T.weisfloggii
T.psuedonana
P.tricornutum
E.hux
Phaeocys:s
Psuedo-nitzschia Thalassiosira
P.minimum
P.micans N.oculata
ChaetocerousT.antarc:ca
Anabaena
Phaeocys:s Psuedo-nitzschia
Thalassiosira
P.calceolata
Compiling5decadesofuptakestudies:
18studiesfrom13researchgroupsShorttermandlongterm(growth)uptake
15phytoplanktonspeciesand28strains5majordivisions(Euks&Cyanos)
16Fe-substrates
~25%ourowndata
StringentdataselecBoncriteria(Felimitedcells,logphase,[Fe]belowthatofVmax,etc..)
U
UU
Time(hrs)
IntracellularFeU
U
Fe-replete
Felimited
Uptakeratebasics&selec(oncriteria
Steadystate
Time(hrs)
IntracellularFe
Fe
Fe Fe
X2
Fe
Fe
Fe
FeFe
Fe
Fe Fe
[Fe]>Kρ
Sub-saturaBon
Vmax
FeconcentraBon
Uptakerate
Uptakeratebasics&selec(oncriteria
Fe
Fe’
Fe’
FeFe’Fe’
Fe'Fe' InorganicFe–limitedbylowsolubility
FeInorganicFe–bufferedbyEDTA
Fe'
Fe'
FeStrongLigands–FeDFB
Uptakeratebasics&selec(oncriteria
UptakeofinorganicIron(Fe')
U
UU
U
UU
UU
U
U
Largecells
Smallcells
growth(days)
shortterm(hrs)
UptakeofinorganicIron(Fe')
Regressionline:DirectproporBonalitybetweenparametersandR2=0.94
Surfaceareanormalizeduptake(kin/S.A)issimilaramongallstudiedeukaryotes
UptakeofsiderophoreboundFe(FeDFB)
Regressionline:DirectproporBonalitybetweenparametersandR2=0.9
UptakeofFe‘andsiderophoreboundFe(FeDFB)
Fe‘(inorganic)
FeDFB(Fe-siderophore)
Surfaceareanormalizeduptake(Kin/S.A)issimilaramongallEuksforFe’andforFeDFB.ButFe’>>FeDFB(x1000)
Up
take
rat
e /
[Fe
Su
b]
ThebioavailabilityenvelopeEmpiricalresultsoflabstudieswitheuks
1.E-13
1.E-12
1.E-11
1.E-10
1.E-09
1.E-08
1.E-07
1.E-061 10 100 1000 10000
k in(Lcell-1hr-1)
surfacearea(μm2)
Fe'
Up
take
rat
e /
[Fe
Su
b]
Comparewithotherorganisms,fieldstudies,differentFesubstrates…
1.E-15
1.E-14
1.E-13
1.E-12
1.E-11
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-050.1 1 10 100 1000 10000
kin(Lcell-1hr-1)
surfacearea(μm2)
marinesynBrackishSynSynechosys)sProchTrichoAnbn
FeDFBeuk
aryotes
Fe' eukaryot
es
Thebioavailabilityenvelope:cyanobacterialuptakekin/S.AissimilaramongallstudiedorganismsforFe’
FeDFBuptakeofcyanosisslowerthanineuks
1.E-13
1.E-12
1.E-11
1.E-10
1.E-09
1.E-08
1.E-07
1.E-061 10 100 1000 10000
k in(Lcell-1hr-1)
surfacearea(μm2)
siderophore porphyrinfreshferrihydrate Fe-dPSsaccharide organicaminenatural humicacid
Thebioavailabilityenvelope:comparingFesubstrates
Fe'
FeDFB
More
bioavailab
le
Less
ligands
Thebioavailabilityenvelope:comparingFesubstrates
MorebioavailableFesubstrates
Fe’FeDFB
LessbioavailableFesubstrates
log(kin/S.A)
ConclusionsandImplica(ons
" WepresentaconvenientframeworkforaddressingbioavailabilitybycomparingacrossFe-substratesandorganisms.
" Feuptakeratesofdefinedsubstratescanbepredictedaccordingtocellsize.
ConclusionsandImplica(ons
# Ifphytoplanktoncannotfurtherincreaseuptakerates,acompeBBveadvantageinFe-limitedwatersmustbegainedthroughalternaBvemeans.
Decreasecellsize,decreaseFedemands,usealternaBveFesources
# Allphytoplanktonarelimitedbythesamefundamentalphysical,chemicalorbiochemicalfactors.Uptakesystemshaveevolvedtooperateattheirmaximalefficiency.
# Phytoplanktonmayemployasimilarironuptakemechanism:reducBveFeuptake
Experimentaldatafor~10cyanosand~30euks!!
Whichphysico-chemicalformcanthecellaccess?
Dissolved(generatedfromtheparBcles)
Availabilityextractedfromsolubility&dissolu(onrates
Howsolubleisthemineral?(chemicalreacBvity,[ligand],lightetc…)
Colloidal/Par(culate(directlyingested)
ThewholepFepoolisavailable
" RemovingFe’(shikingequilibrium)" AcBvedissoluBonbyphytoplankton" Team-upwithbacteria(siderophores)
Cancellsenhancemineraldissolu(onrate? Addbio-mediateddissolu(on
Mineralresidence(meinupperwater Longer-availability
CanphytoplanktonkeepmineralFeattheoceansurface?
AvailabilityofSolidPhaseFetoPhytoplankton:Definingmajorfactorsatplay
Rubinetal.2011
Dust-Fecapturingandmodifica(onbynaturalTrichodesmium
Ydistan
ce(m
m)
00.20.40.60.81.01.21.4
00.20.40.60.81.01.21.4
Xdistance(mm)
SynchrotronstudywithSaBshMyneni
Dust-Fecapturingandmodifica(onsbynaturalTrichodesmium
Rapid&significantFereducBon
Fe(II)
InsituassociaBonwithFe-richparBcles
CenteringofFe-richdust
t0 1hour 1.5hour 24hour
1.01.21.41.61.82.02.22.42.62.83.0
InteracBonMovement RetenBon
Inde
x
NaturaldustAcidcleaneddustFecoateddust
Aveof9Exps30coloniesineach
SensingofFeinpar(clesbyTrichodesmium
t0 1hour 1.5hour 24hour
SensingofFeSensingofFeinpar(clesbyTrichodesmium
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3
Shorttermin
teraction
Overnightretention
BiogenicSilica FecoatedbiogenicsilicaQuartz Fecoatedquartz
0.0E+00
1.0E-09
2.0E-09
3.0E-09
4.0E-09
5.0E-09
6.0E-09
18-Nov 9-Dec 16-Mar 17-Mar 19-Mar 28-Mar 4-Apr 10-Apr 14-Apr
Fewithincells
DissFewithcells
DissSid-Fe(abio(c)
Dust-Fecapturingandmodifica(onsbynaturalTrichodesmium
Feconc(M)
Lowlevelassayfor55Fe-oxdissoluBonwithSid
0.0E+00
1.0E-09
2.0E-09
3.0E-09
4.0E-09
5.0E-09
6.0E-09
18-Nov 9-Dec 16-Mar 17-Mar 19-Mar 28-Mar 4-Apr 10-Apr 14-Apr
Fewithincells
DissFewithcells
DissSid-Fe(abio(c)
Dust-Fecapturingandmodifica(onsbynaturalTrichodesmium
Feconc(M)
Bio-mediated55Fe-oxdissoluBon
Dust-FeuptakebynaturalTrichodesmiumAssistedbyBacteria
LFeL
BACTERIA
?
TRICHODESMIUM
MineralFe
55Fe-Ox,Naturalcolonies,RedSea,Mar2016
0.E+00
4.E-10
8.E-10
1.E-09
-Sid +Sid
Uptake&Dissolutio
nrates
(M/d)
TrichouptBactuptdissolution
Thankyou
PhytoplanktonmayacBvelymineFefrommineralsandeffecttheirfateintheocean
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