Abe S, Takeda J
Institute of Agricultural Environment Control, College of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama 790, Japan.
Plant Physiol. 1988 Jun;87(2):389-94. doi: 10.1104/pp.87.2.389.
When dielectrophoresis and electrofusion of barley (Hordeum vulgare var Moor) leaf protoplasts were assayed in the presence of 0.1 to 1 millimolar lanthanum ion (La(3+)) in the basal medium (0.7 molar mannitol, 1 millimolar piperazine-N, N-bis[2-ethanesulfonic acid]-Na [pH 6.7], 0.1 millimolar CaCl(2)), dielectrophoresis and induction of electrofusion were strongly inhibited. The latter remained inhibited and the former recovered by about 60% after washing the La(3+) -treated protoplasts without EDTA. These inhibitions were almost completely abolished by washing the La(3+) -treated protoplasts with 1 millimolar EDTA. Inductively coupled plasma atomic emission spectroscopic analysis revealed that protoplasts retained a considerable amount of La(3+) after washing without EDTA and released most of the bound La(3+) by washing with 1 millimolar EDTA. This tightly bound La(3+) seemed responsible for the inhibition of electrofusion and dielectrophoresis that was observed in the La(3+) -treated protoplasts after washing. zeta-potentials of protoplasts were -39.0+/-3.2 millivolts, -16.7 +/- 2.6 millivolts, and virtually zero in media containing 0, 0.1, and 0.3 millimolar La(3+) (I = 7.2 millimolar), respectively, and had a positive value (+ 14.2 +/- 2.2 millivolts) in the presence of 1 millimolar La(3+). These effects of La(3+) on zeta-potentials were easily abolished by washing without EDTA. This indicates that charged species located at the surface of plasma membrane of protoplasts cannot account for the sites at which La(3+) exerts its inhibition of dielectrophoresis and electrofusion. In contrast, the promotion of spherical fusion and the reduction of broken fusion products observed in the presence of La(3+) were almost completely abolished by washing without EDTA. Our results also indicate that the initial induction and development of electrofusion can be studied independently.
在基础培养基（0.7摩尔甘露醇、1毫摩尔哌嗪 - N，N - 双[2 - 乙磺酸] - 钠[pH 6.7]、0.1毫摩尔氯化钙）中，当在0.1至1毫摩尔镧离子（La(3+)）存在的情况下测定大麦（Hordeum vulgare var Moor）叶片原生质体的介电电泳和电融合时，介电电泳和电融合的诱导受到强烈抑制。在不使用乙二胺四乙酸（EDTA）洗涤经La(3+)处理的原生质体后，电融合仍受到抑制，而介电电泳恢复了约60%。用1毫摩尔EDTA洗涤经La(3+)处理的原生质体后，这些抑制作用几乎完全消除。电感耦合等离子体原子发射光谱分析表明，在不使用EDTA洗涤后，原生质体保留了大量的La(3+)，而用1毫摩尔EDTA洗涤后释放了大部分结合的La(3+)。这种紧密结合的La(3+)似乎是导致在洗涤后经La(3+)处理的原生质体中观察到的电融合和介电电泳抑制的原因。在分别含有0、0.1和0.3毫摩尔La(3+)（离子强度I = 7.2毫摩尔）的培养基中，原生质体的ζ电位分别为 - 39.0±3.2毫伏、 - 16.7±2.6毫伏和几乎为零，而在存在1毫摩尔La(3+)时具有正值（+ 14.2±2.2毫伏）。La(3+)对ζ电位的这些影响在不使用EDTA洗涤时很容易消除。这表明位于原生质体质膜表面的带电物质不能解释La(3+)发挥其对介电电泳和电融合抑制作用的位点。相反，在存在La(3+)时观察到的球形融合促进和破碎融合产物减少在不使用EDTA洗涤时几乎完全消除。我们的结果还表明，电融合的初始诱导和发展可以独立研究。
