A kinetic analysis of the changes in membrane permeability induced by fertilization in the egg of the sea urchin Sphaerechinus granularis
[摘要] Fertilization-inducedmodificationsineggmembranepermeabilitytolabeledadenineandl-leucinesubstrateshavebeenstudiedbytheinitialrate-pulsetechnique,usingtheseaurchinSphaerechinusgranularis.Kineticparametershavebeendeterminedforunfertilizedeggsaswellasforfertilizedeggsatvariousdevelopmentalstages.Sampleswereusuallyprocessedaccordingtoacentrifuge-washtechnique,sinceMilliporefiltrationwasfoundtobeinadequateinthecaseofleucine.Severalargumentsarepresentedwhichsupporttheviewthattheuptakeofadenineoccursthroughaprocessofsimplephysicaldiffusionacrossthecellmembrane.Ithasbeendemonstrated,ontheotherhand,thatthetransportofl-leucineinvolvesacarrier-mediatedexchange-diffusionprocess.Kineticdatapointtotheexistenceofmajorfluctuationsingeneraleggmembranepermeabilitywhichappeartobelargelyindependentofthemitoticcycleandofthemechanismsinvolvedinthetransportofthesubstratesstudied.Aunitaryhypothesisispresentedtoaccountforthesefertilization-inducedchangesinmembranepermeabilityandwhichdoesnotinvolvethesynthesisorrecruitmentofpreviouslyinactivecarriers.
[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]
