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1、APOPTOSIS:AnoverviewSanjeevSharma*,AartiBhardwaj$,ShaliniJain#andHariomYadav#*AnimalGeneticsandBreedingDivision,#AnimalBiochemistryDivision,NationalDairyResearchInstitute,Karnal-132001,Haryana,India$CollegeofAppliedEducationandHealthSciences,Meerut,U.P.INTRODUCTIONCellde
2、athbyinjury-Mechanicaldamage-ExposuretotoxicchemicalsCelldeathbysuicide-Internalsignals-ExternalsignalsConted…..Apoptosisorprogrammedcelldeath,iscarefullycoordinatedcollapseofcell,proteindegradation,DNAfragmentationfollowedbyrapidengulfmentofcorpsesbyneighbouringcells.(T
3、ommi,2002)Essentialpartoflifeforeverymulticellularorganismfromwormstohumans.(Faddyetal.,1992)Apoptosisplaysamajorrolefromembryonicdevelopmenttosenescence.Whyshouldacellcommitsuicide?ApoptosisisneededforproperdevelopmentExamples:TheresorptionofthetadpoletailTheformationof
4、thefingersandtoesofthefetusThesloughingoffoftheinnerliningoftheuterusTheformationoftheproperconnectionsbetweenneuronsinthebrainApoptosisisneededtodestroycellsExamples:CellsinfectedwithvirusesCellsoftheimmunesystemCellswithDNAdamageCancercellsWhatmakesacelldecidetocommits
5、uicide?Withdrawalofpositivesignalsexamples:growthfactorsforneuronsInterleukin-2(IL-2)Receiptofnegativesignalsexamples:increasedlevelsofoxidantswithinthecelldamagetoDNAbyoxidantsdeathactivators:Tumornecrosisfactoralpha(TNF-)Lymphotoxin(TNF-β)Fasligand(FasL)Historyofcelld
6、eath/apoptosisresearch1800sNumerousobservationofcelldeath1908MechnikovwinsNobelprize(phagocytosis)1930-40Studiesofmetamorphosis1948-49Celldeathinchicklimb&explorationofNGF1955Beginningofstudiesoflysomes1964-66Necrosis&PCDdescribed1971Termapoptosiscoined1977Celldeathgenes
7、inC.elegans1980-82DNAladderobserved&ced-3identified1989-91Apoptosisgenesidentified,includingbcl-2,fas/apo1&p53,ced-3sequenced(Richerdet.al.,2001)Necrosisvs.ApoptosisCellularcondensationMembranesremainintactRequiresATPCellisphagocytosed,notissuereactionLadder-likeDNAfragm
8、entationInvivo,individualcellsappearaffectedCellularswellingMembranesarebrokenATPisdepletedCelllyses,el
