5细菌的遗传和变异e.pptxVIP免费

BacterialGeneticsXiao-KuiGUOPhD第一页，共四十二页。BacterialGenomics第二页，共四十二页。MicrobialGenomics第三页，共四十二页。第四页，共四十二页。第五页，共四十二页。68%DeinococcusradioduransMicrobialGenomeFeaturesG+Ccontent29%BorreliaburgdorferiGenomeorganizationsinglecircularchromosomelargelinearchromosomeplus21extrachromosomalelementscircularchromosomeplusoneormoreextrachromosomalelementstwocircularchromosomes第六页，共四十二页。PLASMIDSPlasmidsareextrachromosomalgeneticelementscapableofautonomousreplication.AnepisomeisaplasmidthatcanintegrateintothebacterialchromosomeClassificationofPlasmidsTransferpropertiesConjugativeplasmidsNonconjugativeplasmidsPhenotypiceffectsFertilityplasmid(Ffactor)Bacteriocinogenicplasmids.Resistanceplasmids7factors).第七页，共四十二页。Insertionsequences(IS)-Insertionsequencesaretransposablegeneticelementsthatcarrynoknowngenesexceptthosethatarerequiredfortransposition.•a.Nomenclature-InsertionsequencesaregiventhedesignationISfollowedbyanumber.e.g.IS1•b.StructureInsertionsequencesaresmallstretchesofDNAthathaveattheirendsrepeatedsequences,whichareinvolvedintransposition.Inbetweentheterminalrepeatedsequencestherearegenesinvolvedintranspositionandsequencesthatcancontroltheexpressionofthegenesbutnoothernonessentialgenesarepresent.•c.Importance•i)Mutation-Theintroductionofaninsertionsequenceintoabacterialgenewillresultintheinactivationofthegene.•ii)Plasmidinsertionintochromosomes-Thesitesatwhichplasmidsinsertintothebacterialchromosomeareatornearinsertionsequenceinthechromosome.•iii)PhaseVariation-Theflagellarantigensareoneofthemainantigenstowhichtheimmuneresponseisdirectedinourattempttofightoffabacterialinfection.InSalmonellatherearetwogeneswhichcodefortwoantigenicallydifferentflagellarantigens.Theexpressionofthesegenesisregulatedbyaninsertionsequences.Inoneorientationoneofthegenesisactivewhileintheotherorientationtheotherflagellargeneisactive.Thus,Salmonellacanchangetheirflagellainresponsetotheimmunesystems'attack.Phas...