Site and timing of synthesis of tubulin and other proteins during oogenesis in Drosophila melanogaster☆

[摘要] ProteinsyntheticpatternsduringoogenesisinDrosophilamelanogasterwereexamined;inparticularthesite,time,andrateoftubulinsynthesisandaccumulationduringoogenesisweredetermined.Ovarianproteinswerelabeledwith[35S]methionineinvivoorinorganculureinvitro,andtheproteinssynthesizedineggchambersofspecificdevelopmentalstagesdisplayedbytwo-dimensionalgelelectrophoresis.Adissectiontechniquewasdevisedtoexamineproteinssynthesizedineachofthethreecelltypespresentinstage10Beggchambers.Themajorityofproteinswhichwereresolvedbytwo-dimensionalgelelectrophoresis,includingtubulinandactin,weresynthesizedthroughoutoogenesisand,atleasttosomeextent,ineachofthestage10Bcelltypes.Proteinsynthesisspecifictodevelopmentalstageand/orcelltypewasalsoobserved;forexample,twononchorionproteinsweresynthesizedonlyinfolliclecellsandprimarilyatstage10.Asensitiveandspecificradioimmuneassaywasdevelopedinordertoquantitatetubulinaccumulation.Synthesisofseveralα-tubulinsubunitsandoneβ-tubulinsubunitwasobserved.Thetubulincontentpereggchamberincreasedfrom3nginstage9to17nginstage14,aperiodofabout13hr.Anaccumulationrateof1ng/hrsuggeststhattubulinmRNAcanaccountforabout4%ofthetotal,nonmitochondrial,poly(A)+RNAoftheegg.Analysisofseparatedcelltypesatstage10Brevealedthatboththefollicleandnursecellssynthesizeandaccumulateappreciableamountsoftubulin.Thestage10Boocytecontainsrelativelylittletubulinbutactivelysynthesizesit.Thesetwocomplementaryanalysesdemonstratethatthetubulinpresentintheeggissynthesizedwithintheoocyte-nursecellsyncytium,firstinthenursecellsandlaterintheoocyte.

[学科分类] 生物科学（综合）