Studies on the biosynthesis and role of diguanosine tetraphosphate during growth and development of Artemia salina☆

[摘要] Analysisoftheacid-solublefractionduringgrowthanddevelopmentofthebrineshrimp,Artemiasalina,usingguanosine-3Handionexchangetechniques,indicatesdiguanosinetetraphosphate(Gp4G)tobepeculiartothefemaleandtobeactivelysynthesizedbythedevelopingovarianegg.Althoughthediguanosinenucleotideshavebeendetectedinotherencystedembryos(thewaterflea,Daphniamagna,andthefairyshrimp,Eubranchipusvernalis),Gp4Gdoesnotappeartobeuniquetoencystedeggs;eggsofthebrineshrimpdestinedtodevelopovoviviparouslycontainsimilaramountsofGp4G.Incontrast,diguanosinetriphosphate(Gp3G)isnotsynthesizedduringoogenesisbutarisesduringcleavageinencystedembryosatleast.Theinabilityofthebrineshrimptoincorporate14C-labeledbicarbonateand/orformateintoacid-solubleornucleicacidpurinesatallstagesofgrowthanddevelopment,whereasthepyrimidinenucleotidesinbothfractionsbecomeheavilylabeled,indicatesArtemiatobeincapableofpurinesynthesisdenovo.ThisisparticularilystrikingduringoogenesiswhenconsiderableamountsofGp4Garebeingsynthesized.Ostensibly,purinenucleotidesynthesisinArtemiarequiresthepresenceofapurineringorcloselyrelatedderivative;theexactnatureofthisrequirementisnowunderstudy.When3H-labeledadenosineandguanosineareintroducedintothemedium,rapidincorporationintopurinenucleotidesoccurs.Finally,Gp4Gappearstobethesolesourceofpurinesfordevelopment.

[学科分类] 生物科学（综合）