Early process on embryogenesis of cultured carrot suspension cells.

胡萝卜悬浮细胞在含有2，4-D的培养基中分离和转移，并在含有10^&lt；-7&gt；M玉米素但缺乏2，4-D的培养基中培养，低密度(&lt；12%Ficoll)的细胞合成花青素，而高密度(&gt；14%Ficoll)的细胞形成体细胞胚胎。1.在培养液中测定培养胡萝卜细胞的膜电位时，膜电位约为-40 mV，不受盐的加入或2，4-D的添加(或去除)的影响。2.在实验介质中(含低盐浓度)进行测量时，其值分布很广(从-60 mV到-110 mV)，且随外界K^+浓度变化较大，但不存在镁离子或钙离子。3.用Ficoll密度梯度离心法分离细胞时，高密度(14%Ficoll)细胞的膜电位约为-150 mV，在去2，4-D的胚胎发育过程中膜电位无明显变化。而密度较低(在6-10%Ficoll之间)的细胞膜电位负值较小(-60~-110 mV)。当这类细胞被转移到含有玉米素但缺乏2，4-D的培养基中培养时，在花青素合成之前，膜电位负移了约15 mV。在含有玉米素的培养液中，当2，4-D被加入到花青素合成细胞中时，在抑制花青素合成之前，观察到了膜的瞬时超极化和随后的去极化。

Carrot suspension cells in a medium containing 2,4-D are fractionated and transferred and cultured in a medium containing 10^<-7>M zeatin but lacking 2,4-D, cells of lower density (<12% Ficoll) synthesize anthocyanin while those of higher density (>14% Ficoll) form somatic embryos. 1. When the membrane potenitals of cultured carrot cells were measured in culture medium, it was about -40 mV and did not change by addition of salts or addition (or depletion) of 2,4-D. 2. When the measurement was performed in test medium (containing low concentration of salts), the values were widely distributed (from -60 to -110 mV)and changed largely with external concentration of K^+ but no Mg^<++> or Ca^<++>. 3. When the cells were fractionated by Ficoll density gradient centrifugation, the membrane potential of the cells of higher density (>14% Ficoll) was about -150 mV in the test medium and did not change during embryogenesis with depletion of 2,4-D. On the otherhand, the membrane potential of the cells of lower density (banding between 6 - 10% Ficoll) was less negative (-60<wave> -110 mV) in the test medium. When such cells were transferred and cultured in the medium containing zeatin but lacking 2,4-D, the membrane potential was shifted negatively by about 15 mV prior to anthocyanin synthesis. When the 2,4-D was added to anthocyanin-synthesizing cells in the medium containing zeatin, a transient hyperpolarization and subsequent depolarization of the membrane were observed prior to the inhibition of anthocyanin synthesis.