Abstract
The chemotactic behavior of Escherichia coli has been studied by exposing cells tethered by a single flagellum to pulses of chemicals delivered iontophoretically. Normally, wild-type cells spin alternately clockwise and counterclockwise, changing their direction on the average approximately once per second. When cells were exposed to a very brief diffusive wave of attractant, the probability of spinning counterclockwise quickly peaked, then fell below the prestimulus value, returning to baseline within a few seconds; repellent responses were similar but inverted. The width of the response indicates that cells integrate sensory inputs over a period of seconds, while the biphasic character implies that they also take time derivates of these inputs. The sensory system is maximally tuned to concentration changes that occur over a span of approximately 2 sec, an interval over which changes normally occur when cells swim in spatial gradients; it is optimized to extract information from signals subject to statistical fluctuation. Impulse responses of cells defective in methylation were similar to those of wild-type cells, but did not fall as far below the baseline, indicating a partial defect in adaptation. Impulse responses of cheZ mutants were aberrant, indicating a serious defect in excitation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 215-226 |
| Number of pages | 12 |
| Journal | Cell |
| Volume | 31 |
| Issue number | 1 |
| DOIs | |
| State | Published - 1982 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Cell Biology
- Molecular Biology
- Medicine(all)
Cite this
Impulse responses in bacterial chemotaxis. / Block, Steven M.; Segall, Jeffrey E.; Berg, Howard C.
In: Cell, Vol. 31, No. 1, 1982, p. 215-226.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Impulse responses in bacterial chemotaxis
AU - Block, Steven M.
AU - Segall, Jeffrey E.
AU - Berg, Howard C.
PY - 1982
Y1 - 1982
N2 - The chemotactic behavior of Escherichia coli has been studied by exposing cells tethered by a single flagellum to pulses of chemicals delivered iontophoretically. Normally, wild-type cells spin alternately clockwise and counterclockwise, changing their direction on the average approximately once per second. When cells were exposed to a very brief diffusive wave of attractant, the probability of spinning counterclockwise quickly peaked, then fell below the prestimulus value, returning to baseline within a few seconds; repellent responses were similar but inverted. The width of the response indicates that cells integrate sensory inputs over a period of seconds, while the biphasic character implies that they also take time derivates of these inputs. The sensory system is maximally tuned to concentration changes that occur over a span of approximately 2 sec, an interval over which changes normally occur when cells swim in spatial gradients; it is optimized to extract information from signals subject to statistical fluctuation. Impulse responses of cells defective in methylation were similar to those of wild-type cells, but did not fall as far below the baseline, indicating a partial defect in adaptation. Impulse responses of cheZ mutants were aberrant, indicating a serious defect in excitation.
AB - The chemotactic behavior of Escherichia coli has been studied by exposing cells tethered by a single flagellum to pulses of chemicals delivered iontophoretically. Normally, wild-type cells spin alternately clockwise and counterclockwise, changing their direction on the average approximately once per second. When cells were exposed to a very brief diffusive wave of attractant, the probability of spinning counterclockwise quickly peaked, then fell below the prestimulus value, returning to baseline within a few seconds; repellent responses were similar but inverted. The width of the response indicates that cells integrate sensory inputs over a period of seconds, while the biphasic character implies that they also take time derivates of these inputs. The sensory system is maximally tuned to concentration changes that occur over a span of approximately 2 sec, an interval over which changes normally occur when cells swim in spatial gradients; it is optimized to extract information from signals subject to statistical fluctuation. Impulse responses of cells defective in methylation were similar to those of wild-type cells, but did not fall as far below the baseline, indicating a partial defect in adaptation. Impulse responses of cheZ mutants were aberrant, indicating a serious defect in excitation.
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U2 - 10.1016/0092-8674(82)90421-4
DO - 10.1016/0092-8674(82)90421-4
M3 - Article
VL - 31
SP - 215
EP - 226
JO - Cell
JF - Cell
SN - 0092-8674
IS - 1
ER -