Nuccitelli R, Jaffe L F
J Cell Biol. 1975 Mar;64(3):636-43. doi: 10.1083/jcb.64.3.636.
Using a newly developed extracellular vibrating electrode, we have made the first study of the spatial distribution of the growth currents around a single developing egg. This pattern was studied during the current pulses wihic traverse two-celled Pelvetia embryos. These pulses can be stimulated to occur with a periodicity of 70 min by mild acidification of the dea water medium. Current enters only at the growing rhizoid's tip while leaving both the base of the rhizoid cell and the whole outer membrane of the thallus cell. The field in front of the rhizoid cell falls off as the inverse cube of the distance from the rhizoid cell's center in the manner of a dipole field. The total inward and outward currents are equal, agreeing with theory. The current density at the rhizoid cell's base is twice that at the top of the thallus cell and this probably represents a change in the outer membrane's properties. There are no significant differences in the durrent density over the thallus cell. These results suggest a model in which the pulse current leaks in through newly opened channels in the growing tip and leaks out elsewhere due to the resultant fall in the membrane potential.
我们使用新开发的细胞外振动电极，首次对单个发育中的卵细胞周围生长电流的空间分布进行了研究。在电流脉冲穿过双细胞鹿角菜胚胎的过程中对这种模式进行了研究。通过对去离子水培养基进行轻度酸化，可刺激这些脉冲以70分钟的周期出现。电流仅在生长的假根尖端进入，同时从假根细胞基部和叶状体细胞的整个外膜流出。假根细胞前方的电场以偶极场的方式随着与假根细胞中心距离的立方反比而衰减。总的内向和外向电流相等，这与理论相符。假根细胞基部的电流密度是叶状体细胞顶部电流密度的两倍，这可能代表外膜特性的变化。叶状体细胞上的电流密度没有显著差异。这些结果提出了一个模型，即脉冲电流通过生长尖端新打开的通道漏入，并由于膜电位的下降而在其他地方漏出。
