Schwartz J L, Garneau L, Masson L, Brousseau R
Institute for Biological Sciences, National Research Council, Ottawa, Canada.
Biochim Biophys Acta. 1991 Jun 18;1065(2):250-60. doi: 10.1016/0005-2736(91)90237-3.
The role of ion channels in the initial steps following exposure of SF-9 lepidopteran insect cells in culture to the delta-endotoxin CryIC from the insecticidal bacterium Bacillus thuringiensis was investigated using single ionic channel measurements and microspectrofluorescence of the calcium-sensitive probe fura-2. It was found that: (1) the toxin triggers an immediate rise in intracellular calcium; (2) the surge is due to calcium entering the cells via calcium channels; (3) the toxin recruits or introduces anionic channels in the cell's plasma membrane in a time-dependent manner. These channels, not seen in the absence of the toxin, are induced by toxin exposure to either side of the cell membrane. They have a conductance of 26 picosiemens (pS) and are mainly permeable to chloride. This study provides the first evidence of the primary role of calcium and chloride ions in the action of delta-endotoxin on cultured insect cells.
利用单离子通道测量技术以及钙敏探针fura-2的显微荧光技术，研究了离子通道在培养的SF-9鳞翅目昆虫细胞暴露于来自杀虫细菌苏云金芽孢杆菌的δ-内毒素CryIC之后初始步骤中的作用。研究发现：（1）毒素引发细胞内钙立即升高；（2）钙升高是由于钙通过钙通道进入细胞；（3）毒素以时间依赖方式在细胞膜上募集或引入阴离子通道。这些在无毒素时未见的通道，在毒素作用于细胞膜两侧时被诱导产生。它们的电导为26皮西门子（pS），主要对氯离子通透。本研究首次证明了钙和氯离子在δ-内毒素对培养昆虫细胞作用中的主要作用。
