Dowd J P, Matsumura P
Department of Microbiology and Immunology, The University of Illinois at Chicago, 60612-7344, USA.
Mol Microbiol. 1997 Jul;25(2):295-302. doi: 10.1046/j.1365-2958.1997.4631830.x.
The purpose of this work was to develop a high-resolution analysis of behaviour as an assay of the physiological consequences of mutations in the che genes and also to examine the role of CheZ in chemotaxis. Recent advances in flash photolysis have made it possible to expose cells to an unstable chemical gradient created by a square-wave increase in attractant concentration. The response of individual cells can be tracked in the order of milliseconds using real-time motion analysis. The tumble frequency of wild-type Escherichia coli exposed to photoreleased aspartate falls very quickly to smooth-swimming levels, and the swimming speed of these cells rises. As a consequence of these behavioural changes, there is an increase in the number of bacteria present in the centre of the flashed area, that is the bacteria's response to the transient gradient generated by flash photolysis was to swim into the centre of the flash area. This allowed the rapid quantitative measurement of chemotaxis. Deletion of various che genes resulted in predictable changes in chemotactic behaviour. cheZ null mutants are non-chemotactic when measured by classical techniques but demonstrate a definite chemotactic response to photoreleased attractant.
这项工作的目的是开发一种行为的高分辨率分析方法，作为检测che基因中突变的生理后果的一种手段，同时研究CheZ在趋化作用中的作用。闪光光解技术的最新进展使得将细胞暴露于由引诱剂浓度的方波增加所产生的不稳定化学梯度成为可能。使用实时运动分析，可以在毫秒级追踪单个细胞的反应。暴露于光释放天冬氨酸的野生型大肠杆菌的翻滚频率会很快降至平稳游动水平，并且这些细胞的游动速度会上升。由于这些行为变化，闪光区域中心的细菌数量增加，也就是说，细菌对闪光光解产生的瞬态梯度的反应是游向闪光区域的中心。这使得对趋化作用进行快速定量测量成为可能。删除各种che基因会导致趋化行为发生可预测的变化。通过经典技术测量时，cheZ缺失突变体是非趋化性的，但对光释放的引诱剂表现出明确的趋化反应。
