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ID:62010686
大小:1.82 MB
页数:36页
时间:2021-04-12
《analysis of a piwirelated gene implicates small rnas in :一个piwi蛋白相关基因分析表明小rna.ppt》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、RNAiinGenomeRearrangementandChromosomeSegragationinTetrahymenaKazufumiMochizuki,YifanLiu,KathleenKarrerandMartinA.GorovskyDepartmentofBiology,UniversityofRochester,Rochester,NY,USAThetwofeaturesofTetrahymenabiologythatwillbeemphasizedareitsnucleardimorphismandthegenomerearrangementsth
2、ataccompanydevelopmentofthesomaticmacronucleus.ItisalsoworthmentioningthatstudiesinTetrahymenaaregreatlyfacilitatedbythefactthatDNA-mediatedtransformationoccursentirelybyhomologousintegrationandbytherecentavailabiltyofthecompletegenomesequenceinsearchable(butnotyetannotated)form.Featu
3、resoftheTetrahymenaSystemNucleardimorphismMassivegenomerearrangementDNA-mediatedtransformationbyhomologousintegrationGenomesequence(searchable,butnotyetannotated)TetrahymenathermophilaMetazoanFungiCiliatePlant1.The2nucleiinTetrahymenaarethemacronucleus(Mac)andthemicronucleus(mic).Thei
4、rpropertiesareillustratedonthenextslide.2.Duringthesexualphaseofthelifecycle(conjugation)2cellsmateandtheMicundergoesmeiosistogiverisetopronucleithatarereciprocallyexchangedbetweenthe2cells,followedbyfertilization.Twopost-zygoticdivisionsfollowandtheproductsdevelopintonewMacsandnewMic
5、s.WhenthenewMacsbegintodevelop,theoldMacbecomespycnotic,undergoesanapoptosis-likedegradationandthendisappears.3.Duringmacronucleardevelopment,10-15%ofthemicronucleargenomeiseliminated.NuclearDimorphisminTetrahymenathermophilaMacronucleus(Mac)TranscriptionallyInert(VegetativeCells)Dipl
6、oid(2C);N=5MitoticDivisionGermlineSomaticlineTranscriptionallyActivePolyploid(~45C);N=250AmitoticDivisionLacks10~15%ofMicGenomeMicronucleus(Mic)Thenextslideillustratesthe2processesthataccountforDNAsequenceeliminationduringMacdevelopment:IES(Internaleliminatedsequence)removalandchromos
7、omefragmentation.InIESremoval,DNAsegmentsrangingfrom0.5-20kbareremovedandthesequencesflankingthemarerejoined.IESremovaloccursatabout6000sitesinthemacronucleargenomeandishighly,butnotperfectly,reproducible.IESremovalaccountsformostofthesequenceelimination.Inchromosomefragmentation,brea
8、kagea
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