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Study_3 (2)

By Veronica Adams,2014-07-19 00:36
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Study_3 (2)study,Study

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AnnualReportofChinaIn

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    ;4114daysafterprotonradiationsurvivepercentmeasurementsofmouseindicatethatmOusses ;surVive100%whentheysufferfromprotonradiationof4and8Gy,survive80%atdoseof16Gy?When ;doseincreaseto32Gy,allofmousedied.

    ;51Besidesthedepilationandburningofskin,somemutationspresenttotheskincellaswellas ;tissuesofheart,liver,kidneyandlung.

    ;33Study0fDNASampleforAtomicForceMicroscopy

    ;CAIMinghui,ZHAOKui,ZHANYong,NIMeinan,

    ;SUILi,KONGFuquan,YANGMing-jian

    ;flSchoolofScience,HebeiUniversityofTechnology,Tianjin300130,China)

    ;AtomicForceMicroscopy(AFM)wasinventedbyBinnig,CalvinFQuateandChristophGerberin ;1986.AFMhasuniqueadvantagesinobservingbiologicalsample.Firstofall,biologicalsamplecanbe ;Observedinphysiologicalenvironment;Second,theforcebetweenAFMtipandsampleisSOlittlethat ;biOlogica1samplecankeepundamaged;Third,nonconductoralsocouldbeobservedbyAFM.Therefore,

    ;AFMhadbeenusedextensivelyinmanyfieldsafteremergencingin1986.

    ;ThereisnodoubtthatthekeypointofusingAFMisthepreparationofthesample.Atpresent,many ;wavs0fDreparingDNAsampleareusedindifferentlabs.TwomethodsofpreparingDNAsampleare ;usedextensivelyineverylabs.First,usebaremicaassubstrate,andaddcationsinDNAsolutionto ;improvetheabsorbedforce;Second,baremicaistreatedwithdifferentreagents,suchascation, ;G1utaraldehyde.SpermidineandSOon.However,therearemanydifferencesinpreparingdetails.Suchas,

    ;DNAconcentration,cationconcentrationandabsorbedtime.Inoneword,differentmethodsaresuitable ;fordifferentexperimentalaims.Wemustfindnewmethodswhicharesuitablef0rthelengthmeasurement

    ;ofDNAandthefragmentsinducedbyradiation,aswellasstatisticalanalysis. ;Thebaremicaisusedassubstratesinthenewmethod.Therearethreestepsinourexperiment:First, ;adjustDNAconcentrationwithainvariableMgconcentration;Second,adjustMg’concentrationwith

    ;ainvariableDNAconcentrationwhichisselectedinthefirststep;Third,adjustsomedetails,suchas, ;abs0rbedtimeandtimesofrinsingsamplewithwater.Byagreatdealofexperiments,DNAconcentration ;andMgconcentrationarefixedon1ng/gLand1mM,respectively.

    ;Fig.1AFMImageofDNA

    ;20nm

    ;1.0nm

    ;O0nm

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    ;FUNDAMENTALANDAPPLIEDFUNDAMENTALRESEARCH.NuclearPhysics89

;Fig.1isthetypicalAFMimageofPUC19plasmidDNA.TheDNAsampleispreparedwithnew

    ;method.TheconfigurationofDNAcanbeclearlyobservedintheFig.1,moreoverthenumberofDNA ;molecularismoderate.WiththenewmethodofDNAsamplepreparation,wecanmeasurethelengthof ;DNAmolecularandtheDNAfragmentsinducedbyradiation,andthenmakestatisticalanalysis. ;SupportedbyNationalNaturalScienceFoundationofChina(10175095,10474018)andPresidentFoundationofChinaInstituteofAtomicEnergy

    ;34DNAEnd-JoiningCatalyzedbyCell-FreeExtracts

    ;AfterDamagedbyHeavyIons

    ;KONGFuquan,ZHAOKui,ZHOUPingkunl,NIMeinan,SUILi,CAIMinghui

    ;(1DepartmentRadiationToxicology,InstituteofRadiationMedicine,

    ;AcademyMilitaryMedicalSciences,Beijing100850,China)

    ;Itisineluctabilitythatthedamagetoastronautwillbeinducedbyheavyionsalongwiththe ;developmenttoouterspace.SotheexperimentofDNAendjoiningcatalyzedbycellfreeextractsaft

    er

    ;DNAdamagingbyheavyionsisdone.

    ;TheDNAsampleispGEM..T1double..strandedplasmidDNAandisofferedbydepartmentof ;radiationtoxicologyofBeijingInstituteofRadiationMedicine,AcademyofMilitaryMedicalSciences.In

    ;theexDeriment,19MeVofLi(LET=120keV/pm,inwater)ionswasgeneratedbyHI13tandem

    ;acceleratoratChinaInstituteofAtomicEnergy(CIAE),andtheDNAsamplesinaqueoussolutionwere ;irradiatedwithvariousdoses(4,6,and8Gy)inatmosphereatroomtemperature.Afterirradiating,DNA ;end-joiningwascatalyzedbycel1.freeextractsinvitrosystem.Fig.1showstheresultofagarosegels ;electr0Dh0resis.

    ;Md46688M446688)

    ;Linear

    ;form

    ;Supercoiled

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    ;Fig.1DNAend-joiningafterirradiatedbyheavyionsLi

    ;aCellfreeextractsis18.8Pg;bCellfreeextractsis6345Pg

    ;Linear

    ;form

    ;Supercoiled

    ;form

    ;InFig.1aandb,Mismarker,4,6and8areDNAirradiatedwith4,6and8Gyrespectively.4,6’and

    ;8’areDNAthatareend-joinedafterirradiatingwithdosesof4,6and8Gyrespectively.

    ;Inagarosegelselectrophoresis,thesupercoiledDNAmovesmorequicklythanthelinearformDNA ;becausethesuDercoiledDNAiscompact.InFig.1,thedimerformDNAliketheexperimentofPETER ;Baumanneta1.Ll_donotappear.

    ;ButthefractionoflinearformDNAincreasesaftercatalyzingbycellfree

    ;extractcontrasttothatbeforecatalyzing.Thisphenomenonismoreevidentinthedoseof6Gythanthat ;inotherdoses.ThereactionsystemFig.1bhasmorecellfreeextractsthanthereactionFig.1a.Soit1s

    ;evidentthattheincreasingoflinearformDNAinreactionsystemFig.1bisstrongerthanthatinreaction ;svstemFig.1a.ItmaybethattherearesomedamagesofbasesandsugarbasesintheDNAthatstillkeep

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