Murvanidze G V, Glagolev A N
J Bacteriol. 1982 Apr;150(1):239-44. doi: 10.1128/jb.150.1.239-244.1982.
Electrical events after a light-dark stimulus were studied in the multicellular organism Phormidium uncinatum. Normally, such a stimulus causes the gliding trichome to reverse direction. By directing a large light spot on the end of a batch of trichomes and then switching it off, we achieved synchronization of the trichomes, since the "head" is much more sensitive than the "tail." The abrupt disappearance of a uniform light produced a depolarization wave which initiated at the head, as registered by externally applied electrodes. The second stimulus produced a depolarization of the opposite direction, reflecting the reorientation of the trichomes. No electrical response was observed at Ca2+ concentrations less than or equal to 10(-8) M. Factors causing oscillatory reversals, i.e., a combination of Ca2+ and A23187, or a viscous environment also abolished the electrical signal. Changes in an externally applied electrical field (4 V/cm2) had little effect on the motile behavior of P. uncinatum or Oscillatoria princeps. However, in the presence of 5 microM Ca2+-1 microM A23187, all the trichomes reversed synchronously to the anode after a change in polarity of an externally applied electrical field. We suggest that an increased Ca2+ concentration together with a change in delta psi (or delta mu H+) represents the taxis signal in cyanobacteria.
在多细胞生物卷曲席藻中研究了明暗刺激后的电活动。通常，这样的刺激会使滑行藻丝体改变方向。通过将一个大光斑照射在一批藻丝体的末端然后关闭它，我们实现了藻丝体的同步，因为“头部”比“尾部”敏感得多。均匀光的突然消失产生了一个去极化波，该波从头部开始，这是通过外部施加的电极记录到的。第二次刺激产生了相反方向的去极化，反映了藻丝体的重新定向。在钙离子浓度小于或等于10^(-8) M时未观察到电反应。引起振荡反转的因素，即钙离子和A23187的组合，或粘性环境也消除了电信号。外部施加电场（4 V/cm²）的变化对卷曲席藻或王子颤藻的运动行为影响很小。然而，在存在5微摩尔钙离子-1微摩尔A23187的情况下，外部施加电场极性改变后，所有藻丝体都同步向阳极反转。我们认为，增加的钙离子浓度以及ψ（或μH⁺）的变化代表了蓝细菌中的趋化信号。
