期刊
EUKARYOTIC CELL
卷 10, 期 9, 页码 1251-1256出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/EC.05066-11
关键词
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资金
- NSF [MCB-0951199]
- NIH [1R01EY019101]
- California Institute of Regenerative Medicine [RB1-01417]
- University of California at Davis (UC Davis)
- Research to Prevent Blindness, UC Davis Ophthalmology, and Yunnan Province Talented Recruiting Program [2009CI127]
- Direct For Biological Sciences
- Div Of Molecular and Cellular Bioscience [0951199] Funding Source: National Science Foundation
Many types of cells migrate directionally in direct current (DC) electric fields (EFs), a phenomenon termed galvanotaxis or electrotaxis. The directional sensing mechanisms responsible for this response to EFs, however, remain unknown. Exposing cells to an EF causes changes in plasma membrane potentials (V(m)). Exploiting the ability of Dictyostelium cells to tolerate drastic V(m) changes, we investigated the role of V(m) in electrotaxis and, in parallel, in chemotaxis. We used three independent factors to control V(m): extracellular pH, extracellular [K(+)], and electroporation. Changes in V(m) were monitored with microelectrode recording techniques. Depolarized V(m) was observed under acidic (pH 5.0) and alkaline (pH 9.0) conditions as well as under higher extracellular [K(+)] conditions. Electroporation permeabilized the cell membrane and significantly reduced the V(m), which gradually recovered over 40 min. We then recorded the electrotactic behaviors of Dictyostelium cells with a defined V(m) using these three techniques. The directionality (directedness of electrotaxis) was quantified and compared to that of chemotaxis (chemotactic index). We found that a reduced V(m) significantly impaired electrotaxis without significantly affecting random motility or chemotaxis. We conclude that extracellular pH, [K(+)], and electroporation all significantly affected electrotaxis, which appeared to be mediated by the changes in V(m). The initial directional sensing mechanisms for electrotaxis therefore differ from those of chemotaxis and may be mediated by changes in resting V(m).
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