Ion movements in a developing fucoid egg☆☆☆
[摘要] RadioisotopeswereusedtomeasurethefluxesofK,Cl,Na,Ca(andtosomeextent,Mg)acrossthemembranesoftheeggsofthebrownalgaeFucusandPelvetiaatdifferentstagesofdevelopment.ThemembranesofunfertilizedeggshavearelativelynonselectivepermeabilitytoK,Na,andClbutdevelopahighdegreeofspecificityforKwithinafewhoursafterfertilization.Atthistime,theoutwardleakageofClfallstoaverysmallfractionoftheinwardflux.ThisallowstheeggstoaccumulateKCl,whichprovidestheosmoticdrivingforceforgrowth.Theinternal[K]:[Na]ratioincreasesbyabout6-foldbythetimeoffirstdivision;thisresults(atleastpartially)froma60%fallinthesodiumpermeability.Finally,membraneconductanceswerecalculatedfromthesetracerdata.Multiplicationoftheseconductancevaluesbythetranscellularvoltagespreviouslyfoundsufficienttopolarizesucheggsgiveseffectivetranscellularcurrentvaluescomparabletothosedrivenbytheeggthroughitself.Thissuggeststhattheendogenouscurrentactsbacktofurtherpolarizethisegg.
[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]
