Protein synthesis in Artemia salina embryos: II. Resumption of RNA and protein synthesis upon cessation of dormancy in the encysted gastrula☆

[摘要] AstudyhasbeenmadeoftheonsetofRNAandproteinsynthesisinencystedgastrulaeofthebrineshrimp,Artemiasalina,duringtheirtransitionfromanametabolic(cryptobiotic)statetoactivelifeandrenewedembryonicdevelopment.Discretesedimentationclassesofpolyribosomesinverysmallamountsweredemonstratedinextractsfromdriedandprehydrated(0°C)gastrulaebysucrosedensity-gradientcentrifugation.Anincreaseinpolyribosomecontentoccurswithin3minutesafterdormancyisterminatedinprehydratedgastrulae,andwithin30minutesingastrulaeincubatedfromthedriedstate.Therateofincorporationof14C-labeledleucineandphenylalanineintoproteininvitrobypreparationsfromdormantgastrulaeisverylowbutincreasesmarkedlywhenmetabolismisresumed,parallelingtheincreaseobservedinthepolyribosomecontentofthesepreparations.Polyuridylicacidstimulates(120-fold)theincorporationofphenylalaninebyribosomepreparationsfromdormantgastrulae;theextentofthisstimulationappearstofluctuateduringtheresumptionofdevelopment.IncorporationintoRNAisroughlylinearingastrulaeduringthefirst2hoursofincubationat30°CusingNaH14CO3aslabeledprecursor.MostoftheincorporatedradioactivityisassociatedwiththetwomajorclassesofribosomalRNA(17Sand26S)and4SRNA.ThepresenceofRNAofhighmolecularweightundergoingrapidturnoverisindicatedbythedistributionofradioactivityandabsorbancebelowthe26SRNApeakofsucrosegradientprofiles.

[学科分类] 生物科学（综合）