Membrane differentiation and de novo synthesis of the (Na+ + K+)-activated adenosine triphosphatase during development of Artemia salina nauplii☆

[摘要] Thedevelopingbrineshrimp,Artemiasalina,naupliusisexploredasanewmodelforthestudyofthebiogenesisofthecationtransportenzyme,(Na++K+)-activatedadenosinetriphosphatase[(Na,K)-ATPase].(Na,K)-ATPaseactivitydevelopsfromundetectablelevelsinpreemergentcysts(embryospriorto12hrofdevelopment)toveryhighlevelsinthenaupliusafter40hrofincubationinseawater[Conte,F.P.,Droukas,P.C.,andEwing,R.D.1977).J.Exp.Zool.202,339],thendeclinesbetween44and72hr.SimilarontogenicpatternsofenzymeactivitydevelopmentareobservedforMg-ATPase,5′-nucleotidase,glucose-6-phosphatase,NADHoxidase(rotenoneinsensitive),andcytochromeoxidase.However,theseenzymesshowmeasurableactivityintheearlycyststage,andthepointsatwhichtheactivityincreasesandthenreachesamaximumareusuallydifferentfromthoseofthe(Na,K)-ATPase.Theseenzymeontogenystudiesdemonstratethatmembranedifferentiationisextensiveduringtheperiodinnaupliardevelopmentwhen(Na,K)-ATPaseactivityappears,andthattheappearanceofspecificenzymesisasynchronousduringembryogenesis.Pulse-chaseexperimentswithNaH14CO3showanincreaseinthespecificradioactivityofthepartiallypurified(Na,K)-ATPasewhichismaximumwhenthelabelisadministeredat12–18hraftertheinitiationofdevelopment.Atthistimethespecificradioactivityincreaseswithpurityoftheenzyme,whereasinearlierpulseperiodsthespecificradioactivityishigherinthemorecrudeenzymefractions,suggestingthatpreferentialsynthesisofthe(Na,K)-ATPaseoccursbetween12and18hr.Radioactivityisfoundinthesubunitsofthepartiallypurified(Na,K)-ATPaseisolatedbysodiumdodecylsulfate-polyacrylamidegelelectrophoresis,andismaximumforthe12-to18-hrpulseexperiment.Thesepulse-chaseexperimentsdemonstratethatthelargeincreasein(Na,K)-ATPaseactivityisduetodenovosynthesisandestablishthatthebrineshrimpisaworkablenewmodelforthestudyofthebiogenesisofthe(Na,K)-ATPase.

[学科分类] 生物科学（综合）