An electrophysiological study of regeneration in Acetabularia mediterranea
An electrophysiological study of regeneration in Acetabularia mediterranea
复制标题
地中海髋臼再生的电生理学研究
作者：
B. Novak;F. Bentrup
摘要地中海无核后茎段（PSS）的极性再生已通过电生理学方法进行了研究。1.在再生过程中，PSS 形成纵向、稳定的电位梯度 U，这反映了跨膜电位 ΔVm 的空间差异，为 5 至 10 mV，即 Vm 的约 5%。而再生在再生后 tr=45 小时左右变得可见。光触发开始，其符号可以在不晚于 t=29 h 时从 U 预测，因为再生发生在 Vmis 最高的细胞极，即细胞质更负的地方（图 3，表 1）。2.通过外部电路将 U 钳位到可比值，导致再生再次发生在 Vmis 最高的地方，尽管在这种情况下，控制 U 的电流 I 的流动与自生电流的方向相反，甚至改变其符号（图 11，表 2）。3.将 U 钳位至零，即消除任何跨细胞电位梯度，至少在 t=60 小时之前抑制极性再生（表 3）。4.U（图 4）和 I（图 12）的自发峰值最早在 t=8 小时时发生（图 5）。这些尖峰出现在假定的再生极，不应期间隔为 10-25 分钟。它们显然反映了传播动作电位（图 7-9），尽管在我们目前的实验条件下，它们仅以电紧张的方式沿着 PSS 传播（图 6）。5.U 和尖峰这两个信号可能是由于 Vm 的生电 Cl 依赖性成分的变化，而不是其 K+ 控制的扩散成分。6.数据允许证实我们的工作假设（第 242 页），该机制空间分化的过程涉及电压依赖性质膜特性，包括激发。
SummaryPolar regeneration of anucleate posterior stalk segments (PSS) of Acetabularia mediterranea has been studied electrophysiologically.1.During regeneration the PSS develops a longitudinal, steady potential gradient, U, which is shown to reflect a spatial difference in the transmembrane potential, ΔVm,of 5 to 10 mV, i.e. about 5% of Vm.While regeneration becomes visible at about tr=45 h after its light-triggered onset, its sign can be predicted from U not later than at t=29 h, because regeneration occurs at that cell pole where Vmis highest, i.e. where the cytoplasm is more negative (Fig. 3, Table 1).2.Clamping U to comparable values by external circuitry causes the regeneration again to occur where Vmis highest, although in this case the flow of the current, I, which controls U is opposite to the direction of the self-generated current, or even changes its sign (Fig. 11, Table 2).3.Clamping U to zero, i.e. eliminating any transcellular potential gradient, inhibits polar regeneration at least up to t=60 h (Table 3).4.Spontaneous spikes of U (Fig. 4) and of I (Fig. 12), occur as early as at t=8 h (Fig. 5). These spikes arise at the presumptive regenerating pole with refractory intervals of 10–25 min. They obviously reflect the propagating action potential (Figs. 7–9) although, under the conditions of our present experiments, they spread along the PSS only electrotonically (Fig. 6).5.Both signals, U and the spikes, are presumably due to changes in the electrogenic Cl-dependent component of Vm,rather than its K+-controlled, diffusive component.6.The data allow to substantiate our working-hypothesis (p. 242) that the mechanism of spatial differentiation involves voltage-dependent plasmalemma properties including excitation.