Cytoplasmic regulation and cyclic variation in protein synthesis in the early cleavage stage of the sea urchin embryo☆

[摘要] Proteinsynthesisinintactseaurchinembryosintheearlycleavagestageshowedcyclicvariationsuperimposedonanincreasingbasalrateofsynthesis.Thecyclicvariationsinproteinsynthesisseemtobecorrelatedwithmitoticdivision,andmaybedirectlyrelatedtothemitoticcycle.Thelengthofthecyclesinintactembryoswasinverselycorrelatedwiththetemperature,buttheamountofproteinsynthesizedduringeachcyclewasapproximatelythesameregardlessofthetemperature.Cyclicfluctuationinproteinsynthesis,initiatedbyfertilization,wasobservedeveninthepresenceofactinomycinD.Cyclesofproteinsynthesiswereobservedevenintheabsenceofnuclearandcytoplasmicdivisionduetotreatmentwithcolchicine,puromycin,andcycloheximide.Similarcyclicvariation,butinmirrorimagetothatofproteinsynthesis,wasobservedinproteolyticactivity.Cell-freesystems(12,000gsupernatant),wherepracticallynoproteaseactivitywasfound,ofseaurchinembryosatvariousstageswereshowntocarryoutproteinsynthesisatratesvaryinginacyclicfashionwithoutincreaseinthebasallevelofsynthesis.Thesecyclicchangeswerenotobservedinintactunfertilizedeggsorincell-freesystemspreparedfromthem.Theperiodicappearanceanddisappearanceofpolyribosomescorrespondingtothecell-freecyclewasobservedonincubationofthe12,000gsupernatantfromfertilizedeggs.Itwassuggestedthatthecytoplasmmayregulateproteinsynthesis,resultingultimatelyinmitoticdivision.Continuousanddiscontinuousproteinsynthesisinthisstageandthenatureofcyclicproteinsynthesisarediscussed.

[学科分类] 生物科学（综合）