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1、10人类染色体畸变chromosomeaberrationAnytypeofchangeinthechromosomestructureornumber(deficiencies,duplications,translocations,inversions,etc.).Althoughitcanbeamechanismforenhancinggeneticdiversity,suchalterationsareusuallyfatalorill-adaptive,especiallyinanimals.1.factorsinducingchrom
2、osomeaberrationA.IonizingradiationIonizingradiationproducesrearrangementsofthegenome.WhenirradiationoccursduringtheG0/G1phaseofthecellcycle,large-scalerearrangementsappearasexchange-typechromosomeaberrationsatthenextmitosis.Suchaberrationscanaltercellularphenotypes,andareimpo
3、rtantinvariousareasofbiology:Medicalandpublic-healthapplicationsincludeperinataldiagnosticscharacterizationofspecificcancertypes,carcinogenesisriskestimation,radiationbiodosimetryandradiotherapeutictreatmentplanning.Analyzingchromosomeaberrationshelpscharacterizerepair/misrep
4、airpathwaysinvolvedintheprocessingofDNAdamage.Ionizingradiationhassomeuniquefeaturesasaprobeofsuchpathways.Comparedtoothergenotoxicagents,itproducescopiousquantitiesofDNAdoublestrandbreaks(DSBs),anditstimingcanbecontrolledmoreaccurately.Moreover,initialradiationdamagehasadisc
5、rete,stochasticcharacterthatcanbemodulatedbyusingdifferentkindsofradiation(e.g.a-particlesversusx-rays)havingdifferentionizationdensities.Thespectrumofdifferentradiation-inducedchromosomeaberrationsisinformativeaboutthegeometryofchromosomesduringinterphase,andviceversa.Chromo
6、somalinstability,inwhichnewaberrations(thoughoftennotofthetypecharacteristicofG0/G1damage)continuetoarisemanygenerationsafterirradiation,representsaformofgenomicinstability,andgenomicinstabilityisprominentduringneoplasticprogression.B.chemicalmutagenAkindofsubstances,suchasdr
7、ugsortoxins,thatcauseschromosomalaberrationsoflivingorganisms,orincreasetherateofmutation.2.chromosomalaberrationsA.chromosomenumericalaberrationNumericalaberrationisachangeinthenumberofchromosomesfromthenormalnumbercharacteristicofthehumanbeings.(1)Euploidyistheconditionofha
8、vinganormalnumberofstructurallynormalchromosomes.Euploidhumanfemales
