Ribonuclease-stable polysomes in the egg of Ascaris lumbricoides☆
[摘要] RibosomesfromprecleavageandcleavingeggsofAscarislumbricoides,pulse-labelledwith3H-uridine,havebeeninvestigatedbydensity-gradientcentrifugation.Ithasbeenfoundthatthereisalargeproportionofribosomalaggregates(polysomes)comparedtosingleribosomesintheeggthroughoutearlydevelopment.Muchofthepolysomefractioninthe0-dayeggisunusuallystable,bothtopreincubationandtolowconcentrationsofRNase.Thisstabilitydecreasesduringcleavage.ExposuretohigherconcentrationsofRNaseresultsinmoreextensivebreakdownofthestablepolysomes,whilepretreatmentwithtrypsinrendersthemsusceptibletolowconcentrationsoftheenzyme.Someofthenewlysynthesized(radioactive)RNAisassociatedwiththestablepolysomesinthe0-dayegg.Duringblastulation,however,muchofthepolysomefraction,andallofthenewlysynthesizedRNAassociatedwithit,isdirectlysusceptibletodecompositionbylowconcentrationsofRNase.Ithasalsobeenshown,bytestingtheproteinsynthesizingcapacityoftheribosomepreparations,thatthestablepolysomesareinactiveinproteinsynthesis,butthattheybecomeactivatedfollowingtreatmentwithtrypsin.ThepossiblesignificanceoftheseobservationsrelativetothebiologyofAscariseggsisdiscussed.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
