Theconcentrationofcalciumfoundinclassicmediaandtheirderivativesvariesfrom0inBGJbMediumFitton-JacksonModification,developedtoculturecartilagenousembryonicbone,to2mMinMCDBmedia201,developedtocultureChickEmbryoFibroblasts,anattachedcellline.Asageneralrule,thehighestconcentrationsofcalciumarefoundinserumsupplemented,suchasFBS,classicmediadevelopedforattachedcelltypes.Seragenerallyprotectscellsfromoxidativedamage.Calciumlevelsaregenerallylowerinserum-freemediaandmediadevelopedforprimaryandclonalcellculture.ThismaybeduetothefactthatprimarycellsandcellsgrownatclonaldensitiesaresusceptIBLetothetoxicinfluxofcalciumthroughcellmembranesdamagedbyoxidativeprocesses,prevalentinserum-freeculturemedia,andenzymaticandmechanicalprocessing.Sincecalciumaffectscellsignalinganddifferentiationaswellascellattachment,mediadevelopedforspecificcelltypesmayrequiresubstantiallyloweredcalciumlevels.
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因为常用的缓冲溶液由弱酸及其共轭酸盐组合而成,当加入酸时,弱酸盐部分转化为弱酸;当加入碱时,弱酸部分转化为弱酸盐。而弱酸在水中不完全电离,弱酸盐在水中可以水解,所以ph变化较小,保持了溶液的PH基本不变。
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