求翻译一段生物论文,请不要用翻译软件.GenomiccontextofstablyandunstablyexpressedtransgenesCharacteristicsofflankingplantDNAOnlyafewreportsprovidecomprehensivedataonthegenomiccontextoftransgenesingeneticallywe

　　求翻译一段生物论文,请不要用翻译软件.

　　Genomiccontextofstablyandunstablyexpressed

　　transgenes

　　CharacteristicsofflankingplantDNA

　　Onlyafewreportsprovidecomprehensivedataonthe

　　genomiccontextoftransgenesingeneticallywellcharacterized

　　lines[24,25,26··].Recurringsequencemotifshave

　　appearedinplantDNAthatflankstransgenesintroduced

　　usingbinaryvectorsandAgrobacterium-mediatedtransfer

　　intodiploidandtetraploidNicotianaspecies.Oftwelve

　　transgenelociexaminedsofar([25,26··];AJMMatzke,

　　JJakowitsch,FMette,CKunz,HvanderWinden,

　　unpublisheddata),matrix-attachmentregions(MARs)

　　havebeenfoundintheflankingregionsoffour;various

　　microsatellitesinthree;highlyrepetitivetandemrepeats

　　intwo;andretroelementremnantsinfive.Exceptfor

　　thefrequentpresenceofbinaryvectorsequences(see

　　below),theremainingDNAcontainsnodefiningcharacteristics.

　　Prokaryoticsequences,aGA-richmicrosatellite,

　　retroelementremnants,andatandemrepeatarrayarethe

　　primaryelementscorrelatedsofarwithsilencing.MARs

　　havebeenassociatedwithsomestablyexpressedinserts

　　[26··].InworkonplantspeciesotherthanNicotiana,

　　highlyrepetitivesequenceshavebeenfoundadjacentto

　　anunstabletransgeneinpetunia[24].Molecularanalysis

　　ofthreeintegrationsitestructuresinricetransformedby

　　directgenetransferindicatedacommonAT-richrepetitive

　　sequenceandtelomericrepeatsatallthreejunctionsofthe

　　targetgenome[27].AdditionalstudiesonDNAsequences

　　flankingtransgeneinsertsarerequiredtosubstantiatethe

　　currentviewthatcertainrepeatsorprokaryoticsequences

　　tendtobeassociatedwithpoorlyexpressedorsilenced

　　inserts.