Severina I I, Skulachev V P, Zorov D B
A. N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, Union of Soviet Socialist Republics.
J Cell Biol. 1988 Aug;107(2):497-501. doi: 10.1083/jcb.107.2.497.
Power transmission along trichomes of filamentous cyanobacteria Phormidium uncinatum has been studied with the use of ethylrhodamine fluorescence as a probe for the transmembrane electric potential difference (delta psi). It is found that agents preventing the light-induced delta psi formation (photosynthetic redox chain inhibitor dibromothymoquinone) or dissipating delta psi (uncoupler tetrachlorotrifluoromethylbenzimidazole) strongly decrease the fluorescence of the ethyl-rhodamine-stained trichomes. K+-H+ antiporter nigericin converting delta pH to delta psi increases the fluorescence. These relationships are in agreement with the assumption that ethylrhodamine electrophoretically accumulates inside the cyanobacterial cells. Illumination of a single cell in the P. uncinatum trichome gives rise to quenching of the fluorescence in this cell and usually in one or two neighbor cells, whereas the rest of trichome remains fluorescing. A small light spot (5% of the trichome length) causes an increase in the ethylrhodamine fluorescence not only in the illuminated but also in the nonilluminated parts of the trichome up to the laser-treated cell or its neighbor(s). It is concluded ethylrhodamine can be used to monitor the power transmission which was previously demonstrated by microelectrode studies of the cyanobacterial trichomes. In certain trichomes, several "dark" cells appear during the storage of the trichomes without energy sources. Illumination for several minutes results in dark cells becoming fluorescing. Thus some cells or cell clusters can be reversibly excluded from the lateral delta psi-transmitting system of the trichome, the rest being still electrically connected. This means that filamentous cyanobacteria possess mechanisms to transmit power along the trichome and to switch off this transmission.
利用乙基罗丹明荧光作为跨膜电势差（δψ）的探针，对丝状蓝藻弯曲席藻（Phormidium uncinatum）毛状体中的能量传递进行了研究。发现能够阻止光诱导δψ形成的试剂（光合氧化还原链抑制剂二溴百里醌）或耗散δψ的试剂（解偶联剂四氯三氟甲基苯并咪唑）会强烈降低乙基罗丹明染色毛状体的荧光。将δpH转化为δψ的K⁺-H⁺反向转运蛋白尼日利亚菌素会增加荧光。这些关系与乙基罗丹明通过电泳在蓝藻细胞内积累的假设一致。对弯曲席藻毛状体中的单个细胞进行光照会导致该细胞以及通常一两个相邻细胞的荧光猝灭，而毛状体的其余部分仍保持荧光。一个小光斑（毛状体长度的5%）不仅会使受照部分的乙基罗丹明荧光增加，还会使毛状体未受照部分直至激光处理的细胞或其相邻细胞的荧光增加。得出的结论是，乙基罗丹明可用于监测能量传递，这一点先前已通过对蓝藻毛状体的微电极研究得到证实。在某些毛状体中，在没有能量来源的情况下储存毛状体时会出现几个“暗”细胞。光照几分钟会导致暗细胞发出荧光。因此，一些细胞或细胞簇可以可逆地从毛状体的横向δψ传递系统中排除，其余部分仍保持电连接。这意味着丝状蓝藻具有沿毛状体传递能量并关闭这种传递的机制。
