; TeX output 2012.11.24:1022papersize=614.295pt,794.96999pt?K{ 5UsGGecrm1728DynamichEnergyBudgetapproacyhtomosdelingmechanismsofnA@ecss05001|%CdSehquanytumdottoxicityn2n3vV ecrm1200NowvembSerl24,2012n4,._c 1 ecrm1000TinU Klanjscek^!T2ecrm07001|2^ 0ercmmi7;\2^2 d,RogerM.NisbGet^ٓRcmr71|s,JohnH.Priester^3RandPatriciaA.Holden^3n5I3%u ecbx0900Abstractn6`J$. ecrm0900A{mecBox1g180,Zagreb,Croatia,R'HR-10002.KE-mail:utin@irb.hr.Phone:+385(915141227 !i-:3KBrenScÒhoAnin-;740 𢱹depthexpGositionofthetheorycanbefoundinKooijman(2010);toverviewscanbefoundinNisbetetal.;741𢱹(2000)U fromanecological,andinSousaetal.(2008)fromamoreformal,theoreticalpGerspective.;742Klanjsceketal.(2012)utilizedDEBtheorytomoGdelgrowthdynamicsofP.Eaerigunosa|pexpGosedto;743𢱹dissolvedQcadmium.pnDatafromQPriesteretal.(2009)guidedmoGdeldesignandparameterization.pnThemoGdel;744𢱹wasabletocapturegrowthdynamicsofbacteriaforexpGosuresrangingfrom0to150mg(Cd(IGI))/Lwitha;745𢱹single cmmi10r=inT*able1).;787MortalityԸwasԹdescribGedusinganagingmoGdulebasedonconceptsfromtheDEBԘtheory(Chapter6in;788𢱹KoGoijman,H2010).L\DEBHtheoryHassumesdamagedpartsofthecells,calledHdamage-inducingcompGounds;789s獒&ٹ2*?K{`M𢱹(DamICs),6causeethedcelltoproGduce`incorrect'proteinswhich,6inturn,5accumulateasdamagetodthecell,;790 𢱹thusincreasingtheprobabilityofdeath.3ThetheorythenlinkstheagingproGcesstopGopulation-levelprocesses;791𢱹byscalingdamage-inducingcompGoundsanddamage, interpretingthescaledquantitiesasagingacceleration;792𢱹andU hazardrate,respGectively*.;793Klanjsceketal.(2012)usedfourstatevqariablestodescribGeabacterialcellintheabsenceofatoxicant:;794𢱹structuralvolume,energyreservedensity*,densityofdamageinducingcompGounds,andhazardrate.H'Limiting;795𢱹substrate>concentration=inthesupGernatantis=thestatevqariablecharacterizing=theenvironment.TTheirmoGdel;796𢱹includedkaknegativefeedbackkfrombacterialmetabGolismtotheenvironment:metabGolicactivitykdegrades;797𢱹theenvironment,which,inturn,slowsdownthemetabGolism;&oxygenlimitationwasidentiedasapGossible;798𢱹culprit.;799Y2.2`Mo_delofdissolvedcadmiumtoxicityz100t𢱹Klanjscek8etal.(2012)suggestedthatbGothdirectexposuretodissolvedcadmiuminthesupernatant(membrane-z101𢱹relatedeects),KandexpGosureduetobioaccumulatedcadmiumwereimpGortant.Theirdissolvedcadmiumz102𢱹toxicity,1moGdel,2includedbotha,2modelof,2exposure(directand,2duetobioaccumulation),4bandamodel,2oftoxicz103𢱹action.cThreejmechanismsofjtoxicactionwerejsuggestedtobGedrivingthegrowthdynamicsofbacteriaz104𢱹expGosedU todissolvedcadmium:z1051. initial\Bretardationofgrowthduetotheneedto\Cinvestenergyinacclimationwhencadmiumispresentz106 inU thesupGernatant,withenergyinvestmentrequiredforacclimationequalacrossexpGosures,z1072. compGetitionersiblyassociatedQDsz127𢱹Quantum|dotsaccumulateonthemembraneinrespGonse|toconcentrationofquantumdotsinthesupGernatant,z128𢱵QO7U,T˭.NBacterialgcellsfareassumedtoencounterQDsrandomly*,%andQDsareassumedtoreversiblyassoGciatez129𢱹withECthemembrane.OnceassoGciated,{QDscandisassociate.Denotingtheratesofassociationanddissociationz130𢱹byU k^PAbR )Gandk^PDbR 殹respGectively*,thedensityofreversiblyassoGciatedQDs,K`y cmr10[=QRb]Z,isthengivenby:z131<$Ad[qŵQRb]Awfe䈟 (֍ ҵdt _=kPAR'QO7U,T !", cmsy108kPDR <6[ SQRb]zrŲ[QRb]۵;`(1)s獒&32?K{`M𢱹wherezriszthebacterialproGductionrate(seeT*able1).(IfassoGciationanddissociationarezmuchzfasterprocessesz132 𢱹than XbacterialproGductionand/orchangesintheenvironment,*equation(1)canbGeassumedtobeinaquasi-z133𢱹steadyU state,hencez134Y[!QRb]&zkRbQO7U,T˭;`(2)whereӵkR =C5kr+BO \cmmi5AR @=qȟ(UWkr+BDRdX O!cmsy7r7)N͸C5kr+BAR @=qȴkr+BDR @ifk^PDbR ,CrG.QNotethattheequation(2)depGendsontheassumptionthatthez135𢱹membraneEareaDispropGortionaltostructuralvolume;seeHanegraafandMuller(2001),KoGoijman(2010),andz136𢱹KlanjscekU etal.(2012)forin-depthdiscussionandexamples.z137YExpQosureduetoirrev>ersiblyassociatedQDsz138t𢱹IrreversibleU assoGciationofQDscanbedescribedbyageneralmassbalanceequation:z139C܍<$õd[qŵQI]ßwfe뻟 (֍ ldtɲ=kIQO7U,T8rŲ[QI];`(3)ЍwhereU kI뵹istheirreversibleassoGciationcoecient.z1402.3.2 MoQdelsofto>xicactionz141tEectsofexpQosureonenergyconductancez142𢱹Energy conductance(v[ٹ) inDEB theorycontrolsbGoththeassimilationrateandtheenergyreserveutilizationz143 𢱹rate.KF*ollowingKlanjsceketal.(2012),FJitisassumedthattheeectsofQDsonvqcanbGedescribedbyaz144𢱹multiplicativeU factorvQDR(T*able1):z145fm vQDTJ=^u cmex10 #18+<$l[30QRb]lwfen (֍{KR^9$۷1Eϟ^LC18+<$l[30QI]lwfe (֍{KI^y۷1W;`(4)c(whereU KR 䂹andKI뵹areinhibitioncoGecients.z146EectsofexpQosureonmain>tenancez147t𢱹MaintenanceKinDEBKtheoryrepresentsthecostofmaintainingthestructureoftheKcell,Mi.e.nukeepingthecellz148𢱹alive.Thisf9includescostf8ofproteinturnover,jdamagef8repair,andf9maintenanceoff8cross-membranegradients.z149𢱹Quantum-2dots-1couldaectthesecostsbGothinsideandoutsideofthecellbyincreasingnecessaryproteinz150𢱹turnover[and\damagerepairrates,Oor(inthecaseofmembrane-assoGciatedQDs)shiftingthebalanceofcross-z151𢱹membraneelectroGchemicalgradients(e.g.e-byscavengingfreeprotons).e,ThisismoGdeledbyassumingeachz152𢱹assoGciatedQDӫincreasesenergycostsataxedrate,wmR c-andmIj`forreversiblyandirreversiblyassoGciatedz153𢱹QDs,U respGectively*.qTheincreaseinmaintenancecoGecientduetoQDs,mQD 2,isthen:z154mmQDTJ=mR: [ 'QRb]xX+8mIA=[ ZQI]:`(5)EectsofexpQosureonR>OSproductionz155t𢱹DEBDtheoryDrecognizesDfreeradicalsandreactiveoxygenDspGecies(ROS)DasamainDcauseofproGductionofz156𢱹damage-inducingw compGoundsw (e.g.DdamagetoDNAvandessentialproteins)and,consequently*,agingandz157𢱹cellVdamageU(KoGoijman,2010,pp.8 209-214).8!AgingaccelerationisascaledmeasureofaccumulatedlevelVofz158𢱹damage-inducingU compGoundsanddeterminestherateofincreaseofthehazardrate.z159AnyassoGciatedQDѱisassumedtobGeabletoincreasethehazardratebyincreasingproGductionofROSz160𢱹and,!:therefore,increase@agingaccelerationA(q[ٹ)?).[TheQD-relatedadditiontotheagingacceleration,!:(ɟ5dq =qȴdtв)QD+2,z161𢱹is:z162f^<$dqwfe  (֍dt0ݟ^Q QDᛲ=kPIq@LR y[QRb]8+kPIq@LI*[QI];`(6)whereU k^PIbq@LR andk^PIbq@LI JaretoxicityU parametersforreversiblyandirreversiblyassoGciatedQDs.z163Ifapproximation(2)holds,Q:[WQRb]uwinequations(4)-(6)canbGereplacedwithkRbQO7U,T˭.ΌSincekR 1alwaysz164𢱹appGears&incombination'withanotherparameter,thoseparameterscanbGescaledbykRb,andkR Ccanbesetz165𢱹toU unitywithoutthelossofgenerality*.z166s獒&ٹ4H?K{`MEectsofexpQosureonacclimationz167t𢱹ExpGosureVtoUanewenvironmentcanVtriggerarespGonse(e.g.5!F*eriancetal.,1998;W*angandCrowley,2005;z168 𢱹PagesBetBal.,2007),~;whichBslowspGopulationgrowthBuntilbacteriaacclimateB(e.g.:proGductionofBcadmiumz169𢱹euxLmachineryLasinGibbGonsetal.(2011)).nCompletesuppressionofgrowthforapGeriodLoftimethatcanz170𢱹happGenwhentheretardationisstrongenough-and/oriscombinedwithothertoxiceects-iscommonlyz171𢱹describGedasalagtime.Previousstudiescharacterizedlagtimeasaconsequenceofenergyinvestmentforz172𢱹overcomingahurdle(BaranyiandRobGerts,1994),[suppressionofdivisionuntilcellsreachanenvironment-z173𢱹depGendentsize(HillsandMackey,1995),orsimplyanempiricallyderivedfunctionofpreviousgrowthandz174𢱹environmentalU states(Munoz-Cuevqasetal.,2010).z175Klanjsceketal.(2012)broughttheseconceptswithintheDEBframeworkbyassumingthatpartofthez176𢱹energy6ux6avqailableforgrowthis6divertedtoacclimationuntil6cellsarecompletelyacclimated.gLTheydenez177𢱹a:newstate:vqariable,?acclimationenergydensitya(seeT*able1fordynamics),?whichdictatesthepropGortionz178𢱹ofU energydedicatedtoacclimationuntilareachesthetargetacclimationenergydensity*,aM\.z179T*argetacclimationenergydensity(aM\)could,inprinciple,bGedierentforeachtreatment,orthesamez180𢱹forѳalltreatments.8IfitweredierentforeachѲtreatment,onewouldexpGectaѲcorrelationbetweenѳaM andz181𢱹expGosure.p)SinceQtheyQdidnotseeanycorrelation,QKlanjsceketal.(2012)assumedthesamevqalueforaM 1vforz182𢱹all*qexpGosures,2butnotedthataM ͹forthe*rlowest*qexposurescouldbeoverestimated.cFIn*qthismanuscript,2aM ͹isz183𢱹allowedU tofreelyvqaryacrossexpGosures.z184Y2.4`Quantumdotdissolutionz185𢱹AmoGdel=of>QDdissolutionisimpGortantbecause=ourapproachtoQDtoxicity>heavilyrelies>onpredictionsz186𢱹ofttheuioniccadmiumtoxicitytmoGdel.}AbsentunderstandinguofthephysicsofuQDYdissolution, anempiricalz187𢱹representationj7isadoptedj8basedonmeasurementsbyj8Priesteretal.(2009),o}whomeasuredtime-evolutionofz188𢱹dissolved8cadmiuminanabioticenvironmentwith758mg/L7totalcadmiumintroGducedasQDs,pڵC^Al75x,andz189𢱹concentrationofdissolvedcadmiumforallbiotictreatments,SC^B(,atsixhours(T*able3).aTheyfoundthatz190𢱹dissolvedU cadmiumintheabiotictreatmentcanbGedescribedbythedissolutioncurvegivenbyz191'KCA፱75x(t)=<$ 2:5tKwfe!p (֍18+0:1t&:`(7)~AssumingtheproGcessesunderlyingdissolutionand,%therefore,theshap}/eFofalldissolutioncurvesfollowsthatz192𢱹of_the_abiotictreatment,bgdissolutioncurves_foralltreatmentsarecreatedbyrequiringthatthecurvepassesz193𢱹throughthesix-hourpGointmeasuredbyPriesteretal.(2009)forthatparticulartreatment._Denotingthez194𢱹dissolutioncurveforexpGosureofxmg/LtotalcadmiumintroGducedasCdSeQDswithC^Bx(,{andthe6-hourz195𢱹measurementU forthesameexpGosurewithC^Bx((6):z196f'CBx((t)=<$j*C^Bx(6)Kwfee m~C:Al75x(6)!3CA፱75x(t):`(8)!2.5`Datacalibrationz197𢱹ThebacterialgrowthcurvesbyPriesteretal.(2009)comeprimarilyfrommeasurementsofopticaldensityz198𢱹(OD).nThenrelationshipofODnjtocellcountisnon-linear(Begotetal.,1996);|thusinthestudyofionicz199𢱹toxicity*,oKlanjscekCetBal.(2012)usedacalibrationcurveobtainedfromaseparateexpGerimentrelatingOD.toz200𢱹cellU count:z201OG0፴D = 1|sOD@e Zcmr52 OmD6;`(9)whereU 1ѓand 2arecalibrationparameterslistedinT*able2.z202QDs,M|however,mayaectOD5inotherways. +Calibration(9)reliesontheassumptionthatopticalz203𢱹characteristicsuofudispGersioncentersremainsconstant.Thisassumption,~5however,doGesunotseemtouholdforz204𢱹stationarykgrowthphasesinQDktreatmentsinPriesteretal.(2009).After24khours,qtheODkmeasurementsz205𢱹for5some5ofthehigherexpGosuresarehigherthanthoseoflower5expGosures(e.g.gcalibratedOD5is11.5forthez206𢱹control,and|13|for37.5mg/L|expGosure),butbacterialcountsarelower|forthetreatmentsthanthecontrolz207𢱹(5:210^10 cforthecontrol,and2:110^10forthe37.5mg/Ltreatment).3kThissuggeststhat,atleastinthez208𢱹stationary-growth-phase,cOD-Visnotareliablemeasureofcelldensity*,cwhichforbacteria-shouldcorrelatez209𢱹closelyU withbiomass.z210s獒&ٹ5_)?K{`MT*odeterminethepGointwhereODdatastarteddivergingfrom(9),anewexpGerimenthasbGeenperformedz211 𢱹withWthesameVmaterialsandmethoGdsasinPriesteretal.(2009),*inwhichODIwashourlyrecorded,*andcellz212𢱹counts(after8,13,and18hours)wereconductedforgrowthofP.& aerigunosaGexpGosedtofourconcentrationsz213𢱹ofJCdintroGducedasQDs(0,(12,(30,andJ60mg/L).Thedataconrmedthatover18hours,(i.e.lthetimez214𢱹pGeriod]{overwhich]|growthrateconstantswerecalculated]|inPriesteretal.(2009),_OD]yispropGortionaltocellz215𢱹concentrations.Y.Conservqatively*, SinthecurrentstudyonlyODdataupto15hourscalibratedwith(9)arez216𢱹used.z217Y2.6`Mo_delttingandtestingz218t𢱹InYordertoXteaseoutmechanismsofnanotoxicity*,thevqalidityXofmechanisms,equations,andYparametervqaluesz219𢱹foruCd(IGI)utoxiceectsproposedinKlanjscekuetal.(2012)wasassume}/d.ThusonlytheQDutoxicity-relatedz220𢱹parametersneededtobGetted.IfalltoxiceectswereopGeratingsimultaneously*,@eightparameterswouldz221𢱹havetobGettedinadditiontotargetacclimationenergydensities.GxThepGopulationgrowthdatadidnothavez222𢱹informationsucientforttingsuchalargenumbGerofparameters,"soonlyonemechanismatatimehasz223𢱹bGeentted.3ThisapproachaimstoidentifythestrongestofthecandidatemechanismsandhasbGeenusedz224𢱹inamanypreviousatoxicologicalapplicationsofDEBatheorya(KoGoijmanandBedaux,1996;Jageraetal.,2006;z225𢱹JagerU andKlok,2010).z226ThemoGdelswerettedtodatausingMA*TLAB'snlint.mleastsquaresttingroutine.-Themodelwasz227𢱹simulatedusingproprietarycoGdewritteninMA*TLAB,andsquareofthedierencebGetweenobservedandz228𢱹simulatedncellconcentrationmforagivensetofparametersmwascalculated.jTheparametermvqaluesweread-z229𢱹justedusingLevenbGerg-Marquardstepadjustments,.andtheproGcesswasrepGeateduntilreachingconvergence.z230𢱹GoGodnessoftasrepresentedbyresidualsumofsquaresoeredacruderankingofthemechanismsthatwasz231𢱹usedWytoexcludethemostill-ttingones.xMoreformalstatisticalmethoGdsofmodelselectionaswereusedinz232𢱹previousecotoxicologicalapplicationsofDEBtheorywerenotadoptedhere.EThiswasbGecausepreviousworkz233𢱹adopting`pthis`oapproachbyMuller`oetal.(2009)yieldedtheimplausibleresultthatsimilartoxicant-organismz234𢱹combinationswerenotnecessarilybGestdescribedbythesametoxicitymechanisms.xInaddition,formalz235𢱹moGdelselectioncoulddiscardvqalidmechanismsbGecauseitscorestheassumedfunctionalformrepresentingz236𢱹theU mechanism(usingtherequirednumbGerofparameters),notjusttheplausibilityofthemechanismitself.z237!֍3cResultsz238~𢱹First,xdissolvedAlcadmiumAmtoxicitywasinvestigatedtoestimateeectsAmofexpGosuretoQDsthatcanbGeexplainedz239𢱹bycadmiumdissolvingfromQDs.ONext,ӌtheabilityofassumedQDtoxicitymechanismstoexplainthez240𢱹remainingbutthat9QDsthemselvesarenot.h(Hence,>theonlysourceof9toxicityinthisscenario9isthedissolvedz249𢱹cadmiumU describGedby(8).z250Neitherscenariocapturesthedata.'T*otal-cadmiumdrivensimulationsoverestimatetheeectsoflower,z251𢱹anduunderestimateutheeectsofhigherexpGosures(Figure2,}toppanel).Dissolutiondrivensimulationsustillz252𢱹overestimatettheteectsofthelowestexpGosuret(10mg/L),butgrosslyunderestimateeectsofalltheotherz253𢱹expGosures,¦provingythisscenarioyincapableofcapturingevenrudimentarytoxicyeects(Figure2,¦bGottomz254𢱹panel).,(TheYinabilityXofeitherscenariotocapturethedatastronglysuggeststhatQDItoxicityXisindeedanz255𢱹impGortantU eectseparatefromthetotaland/ordissolvedcadmiumexpGosure.z2563.2`CdSeQDtoxicityz257t𢱹AsU indicatedinMoGdeldevelopmentU section,therearethreeroutesofinvestigation:z258s獒&ٹ6y?K{`M1. ac}/climationeects:qequalU vs.vqariabletargetacclimationenergydensityacrosstreatments,z2592. asso}/ciationVtypeeects:QDszreversiblyzvs.|irreversiblyassoGciatedzwiththecelladdingoneparameterz260 each,U andz2613. metab}/olicʷeects:"eectsonmaintenance,energyconductance,andmortality(increaseinagingaccel-z262 erationU rate);eachmetabGoliceectaddsoneparameterperassociationtype.z263𢱹AnycombinationofmetabGoliceects(includingnone)couldbeoperational(eightcombinations),ٙatleastonez264𢱹butpGossiblybothassociationtypeeectscouldoperate(threecombinations),@andtwoacclimationeectsz265𢱹are pGossible.WThisgivesatotalof48possiblecombinations.WThedataarenotextensiveenoughtoallowne-z266𢱹tuning$tothedegreenecessaryto#distinguishbGetween$multipleeectsopGeratingatthesametime.M,Therefore,z267𢱹only?!dominant? eects-thosethatcanexplainthegreatestpGortionofthedata-canbGeinvestigated.j+This?!isz268𢱹done̙sequentially*,wutilizingthesum̘ofsquaredierencebGetweendataandsimulations̘forallcurves(RSS)z269𢱹asU aguide.z270First,$QDsareassumedtoaectonlyacclimationbyallowingaM ktovqarybGetweentreatments.Thez271𢱹resultingyt(Figure3,etoppanel)isaremarkqableimprovementyonthezRSS obtainedforconstantaM\,z272𢱹suggestingU3aU4signicantimpGortanceofQDTeectsonacclimation.qAlthoughallowedU3tovqaryfreelyacrossz273𢱹expGosures,U aM 5|increasedwithexposureforallmechanisms(Figure3,bottompanel).z274T*otesttheimpGortanceofmetaboliceects,besttsofeachmetaboliceectforbothassociationtypesarez275𢱹simulated@whileallowing@aM tovqaryacrosstreatments;Gesimulationssuggestthat@allconsideredphysiologicalz276𢱹mechanisms[canimprovethets(Figure4).Inaddition,]aM <:retainsthequalitativepatternobservedinthez277𢱹bGottom0-panelof0,Figure3(patternsnotshown).e/ThisconsistencysuggestsvqariableaM doGesnotimprove0-thez278𢱹ts+ItalsosuggestsprioritizationoffutureexpGerimentalresearch,notablytheneedforz355𢱹aRmuchSbroaderbaseofdataontheinterplayofSbioticandabioticeectsonQD)dissolution.RFinally*,_thez356𢱹researchbTexpGosesalimitationofcurrenttheoryforecotoxicologybasedonDEBbtheory*. DEBtheorybTisabstractz357𢱹and;%reliesonconceptssuchasdamage;$inducingcompGounds.hRelatingtheseconceptstospecicmechanismsz358𢱹suchJasJoxidativestressrequiresJmakingtighterlinksbGetweenJthetheoryandmeasurablequantities.nThisisz359𢱹aU priorityforourfutureresearch.z360s獒&ٹ8 Ѡ?K{`M5cAccknowledgementsz361~𢱹W*ethankErikMullerforusefuldiscussionsonthemechanismsoftoxicity*.*TheresearchwassuppGortedbyz362 𢱹US*National+Science*F*oundationundergrantEF-0742521.TherewasalsosuppGortfrom*theUS*Nationalz363𢱹ScienceF*oundationandtheUSEnvironmentalProtectionAgencyunderCoGoperativeAgreementNumbGerz364𢱹EFU 0830117,andCroatianMinistryforScience,EducationandSpGortgrant098-0982934-2719.z365!֍6cEthicalG\standardsandconictofincterestz366𢱹ExpGeriments{performedzhereincomplywiththecurrentlawszoftheUnitedStatesofAmerica.5Theauthorsz367𢱹declareU thattheyhaveU noconictofinterest.z368!֍Referencesz369𢱹J.*"Baranyi*!andT.A.RobGerts.kA)dynamicapproachtopredictingbacterialgrowthinfoGod.kInternationalz370JournalofF;o}/odMicrobiology,U 23:277294,1994.z371𢱹C.Begot, I.Desnier,J.D.Daudin,J.C.Labadie,andA.LebGert.Methodsforcalculatinggrowthparametersz372byU opticaldensitymeasurements.nJournalofMicr}/obiologicalMethods,U 25:225232,1996.z373𢱹Jinfeng8Chen,JiangangY*uan,Shanshan7Wu,Biyun8Lin,andZhongyiY*ang.Distributionoftraceelementz374contamination&in%sedimentsand%riverineagricultural%soilsofthezhongxinriver,southchina,and&evqaluationz375ofU loGcalplantsforbiomonitoring.nJournalofEnvir}/onmentalMonitoring,U 14:26632672,2012.z376𢱹P*.WFerianc,A.Farwell,andVT.Nystrom.ThecadmiumstressstimulonVofEscherichia)*c}/oli k-12.Microbiology,z377144(4):10451050,U 1998.z378𢱹SeaniM.GibbGons,KevinF*eris,MicheleA.McGuirl,SergioE.Morales,AnuHynninen,PhilipiW.Ramsey*,andz379JamesEE.Gannon.oftheRoyal >SocietyB,365,72010.qdoi:(n10.1098/rstb.2010.0137.z388𢱹T.zJager,SE.H.W.zHeugens,andS.A.L.M.zKoGoijman.Makingsenseofecotoxicologicaltestresults:kT*owardsz389applicationU ofproGcess-basedmodels.nEc}/otoxicology,U 15(3):305314,2006.z390𢱹TjallinglJagerlandElkeI.Zimmer.+SimplieddynamicenergybudgetmoGdelforanalysingecotoxicityldata.z391Ec}/ologicalModelling,U 225:7481,2012.z392𢱹ArturoA.Keller,HongtaoW*ang,DongxuZhou,HunterS.Lenihan,GaryCherr,BradleyJ.Cardinale,z393RobGertwMiller,4andwZhaoxiaJi.[Stabilityandaggregationwofmetaloxidenanoparticlesinnaturalaqueousz394matrices.nEnvir}/onmentalScience&T;echnology,U 44(6):19621967,2010.z395𢱹T.#Klanjscek,R.M.NisbGet,J.Priester,andP*.A.Holden.yMoGdeling"physiologicalprocessesthat"relatetoxicantz396expGosureU andbacterialpopulationdynamics.nPL}/oSONE,7(2),2012.doi:10.1371/journal.pGone.0026955.z397𢱹S.A.L.M.tGKoGoijman.&DynamicEner}/gyBudgettheoryformetabolicorganisation,43rded.&CambridgetGUniversityz398Press,U GreatBritain.ISBN9780521131919.,2010.z399𢱹S.A.L.M.>KoGoijman?andJ.J.M.Bedaux.TheGpanalysisofGoaquatictoxicitydata.VU*University>Press,Amster-z400dam,U 1996.z401s獒&ٹ9 s?K{`M𢱹ErikB.Muller,5RogerM.NisbGet,6andHeatherA.Berkley*.Sublethaltoxicanteectswithdynamicenergyz402 budgetU theory:qmoGdelformulation.nEc}/otoxicology,U 19(1):3847,2009.DOI10.1007/s10646-009-0385-3.z403𢱹M.ZMunoz-Cuevqas,\;P*.S.Fernandez,\:S.George,\;andC.Pin.MoGdelingthelagperiodandexponentialgrowthz404oflisteriamonoGcytogenesunderconditionsofuctuatingtemperatureandwateractivityvqalues.;Applie}/dz405andEnvir}/onmentalMicrobiology,U 76(9):29082915,2010.z406𢱹R.M.&NisbGet,E.B.Muller,K.Likqa,andS.A.L.M.KoGoijman.RF*rommoleculestoecosystemsthroughdynamicz407energyU budgetmoGdels.nJournalofAnimalEc}/ology,U 69(6):913926,2000.z408𢱹D.Pages,MWL.Sanchez,MVS.ConroGd,MWX.Gidrol,A.F*ekete,P.Schmitt-Kopplin,MWT.Heulin,andW.Achouak.z409ExplorationNofintraclonaladaptationmechanismsofPseudomonasbr}/assicacearumXfacingNcadmiumtoxicity*.z410Envir}/onmentalMicrobiology,U 9(11):28202835,2007.z411𢱹J.H.Priester,HP*.K.Stoimenov,R.E.Mielke,S.M.W*ebb,C.Ehrhardt,J.P*.Zhang,G.D.Stucky*,andP*.A.z412Holden. Eects5iof5hsolublecadmiumsaltsversuscdsequantumdotsonthegrowthofplanktonicPseu-z413domonasaeruginosa.nEnvir}/onmentalScience&T;echnology,U 43(7):25892594,2009.z414𢱹T.ISousa,T.Domingos,andS.A.L.MIKoGoijman.GF*romempiricalpatternsItotheory:ZaformalmetabGolicz415theoryU oflife.nPhilosophic}/alT;ransactionsoftheRoyalSocietyB,U 363(1502):24532464,2008.z416𢱹F*rankvonderKammer,P.LeeFerguson,PatriciaA.Holden,ArmandMasion,KimR.Rogers,StephenJ.z417Klaine,AlbGert!A.Koelmans,Nina"Horne,andJason!M.Unrine.Analysisofengineered"nanomaterialsinz418complexY.matricesY/(environmentandbiota):yGeneralconsiderationsY/andconceptualcasestudies.zEnvir}/on-z419mentalT;oxic}/ologyandChemistry,U 31(1):3249,2012.z420𢱹A.lW*anglandD.E.Crowley.GlobalgenelexpressionrespGonsestocadmiumtoxicitylinEscherichiac}/oli.Journalz421ofBacteriolo}/gy,U 187(9):32593266,2005.z422s獒ק10 ߊ?K{`M7cFigureG\legendsz423~ FigureU1:rOOverviewoftheapproach.rBacterialgrowthanddissolvedcadmiumUtoxicitymoGdelfromz424 Klanjsceketal.(2012)(shadedbGoxes)areusedtopredicttheresponseofbacteriatocadmiumresultingz425 from0EQD0ANAacmr675N(6)C-:AN75N(t) jp 鍍azexpQX.R]dK cmsy8\tkX.RQX.O1UT6p^Ynexpq7R ¿[QX.R]+k-:6I>q7I㸿[QX.I?] } pp rtMoC7CX.O1UT8k-:6O>C[CX.IvN 0]rq7C f[CX.IvN 0] ^pp rBacterial(p;=mꍑ bS33*\)@SV +KX.S p ֍'obacterial(pro4Units Std.v$alueZ@ @ tQD(toÒxicityparameters@ @ ٍkX.ImꍑFB$L9*\)7h(C-mol{\girrevÒersible(assoq7Rmꍑ=C-mol=b*\) mg(h`b3\[QX.R]toÒxicityVM0.00026q2 @ $k-:6I>q7Imꍑ=C-mol=b*\) mg(h`b3u'[wYQX.I?]ytoÒxicity((kX.Ir=\t0:00785i@1#Ս2 )0.01q2@ @ rE>PÒarameters(adoptedfromKlanjsceketal.(2012)Z@ @ ٍ KX.Smꍑ=C-mol=џ*\)@SLhalf-saturation(constanÒt ÿ10-:7 q16@ |捍vAEh-:1cenergy(conductancea0:84768@ mAEh-:1rmainÒtenance(ratea0:30911@ "gAԍn.d.1inÒvestment(ratio3:369810-:3@ ٍDdsqmꍑFB$L=џ*\)@C-molS4mÒultiplicative(stresscoq7Cmꍑ=C-mol=b*\) mg(h-:3~ dissolvÒed(cadmiumtoxicityUa0:21352q2 @ k-:6I>CmꍑFB$L9*\)7h(C-mollcadmium(inuxcoCAEh-:1cadmium(euxcoo3:6,1t0:46@ @iv:Tҟ#1= =C-mols=enÒvironmental(degradationco cmmi10 0ercmmi7O \cmmi5K`y cmr10ٓRcmr7Zcmr5u cmex101