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1、RNA沉默在植物逆境生物中的作用Abstract:Antimicrobialpeptides,includingdefensins,arecomponentsoftheinnateimmunesysteminticksthathavebeenshowntoprovideprotectionagainstbothgram-negativeandgram-positivebacteria.Varisin,oneofthedefensinsidentifiedinDermacentorvariabili
2、s,wasshowntobeproducedprimarilyinhemocytesbuttranscriptlevelswerealsoexpressedinmidgutsandothertickcells.Inthisresearch,westudiedtheroleofvarisinintheimmunityoftickstothegram-negativecattlepathogen,Anaplasmamarginale.Expressionofthevarisingenewassilen
3、cedbyRNAinterference(RNAi)inwhichmaletickswereinjectedwithvarisindsRNAandthenallowedtofeedandacquireA.marginaleinfectiononanexperimentally-infectedcalf.Silencingexpressionofvarisininhemocytes,midgutsandsalivaryglandswasconfirmedbyrealtimeRT-PCR.Weexpe
4、ctedthatsilencingofvarisinwouldincreaseA.marginaleinfectionsinticks,buttheresultsdemonstratedthatbacterialnumbers,asdeterminedbyanA.marginalemsp4quantitativePCR,weresignificantlyreducedinthevarisin-silencedticks.Furthermore,coloniesofA.marginaleintick
5、susedforRNAiweremorphologicallyabnormalfromthoseseeninelutionbufferinjectedcontrolticks.ThecolonyshapewasirregularandinsomecasestheA.marginaleappearedtobefreeinthecytoplasmofmidgutcells.Sometickswerefoundtobesystemicallyinfectedwithamicrobethatmayhave
6、beenrelatedtothesilencingofvarisin.ThisappearstobethefirstreportofthesilencingofexpressionofadefensininticksbyRNAithatresultedinreducedA.marginaleinfections.引自:KatherineM.KocanÆJose´delaFuenteÆRau´lManzano-RomanÆVictoriaNaranjoÆWayneL.HynesÆDanielE.So
7、nenshineSilencingexpressionofthedefensin,varisin,inmaleDermacentorvariabilisbyRNAinterferenceresultsinreducedAnaplasmamarginaleinfectionsExpApplAcarol(2008)46:17–28DOI10.1007/s10493-008-9159-5RNA沉默在植物的逆境生理中具有重要作用,植物中已经发现了多种小RNAs,如miRNAs和siRNAs。其中siRNA
8、s可以由外源性核酸产生,如侵入的病毒,这种外源性siRNAs是植物、真菌和一部分动物重要的抗病毒机制。siRNAs也可以由植物自身基因组转录物产生,如天然反义转录siRNAs(natsiRNAs)和长小干扰RNAs(longshortinterferingRNAs,lsiRNAs),这些内源性siRNAs和miRNAs一样,不仅可以调节植物基因表达,而且在植物防御细菌和食草动物过程中也具有重要作用。病毒或细菌则分别进化出了病毒沉默抑制子(ViralsuppressorsofRNAs
