Impulse responses in bacterial chemotaxis

Steven M. Block, Jeffrey E. Segall, Howard C. Berg

Research output: Contribution to journalArticle

179 Citations (Scopus)

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 languageEnglish (US)
Pages (from-to)215-226
Number of pages12
JournalCell
Volume31
Issue number1
DOIs
StatePublished - 1982
Externally publishedYes

Fingerprint

Chemotaxis
Impulse response
Defects
Methylation
Escherichia coli
Flagella
Direction compound

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 journalArticle

Block, Steven M. ; Segall, Jeffrey E. ; Berg, Howard C. / Impulse responses in bacterial chemotaxis. In: Cell. 1982 ; Vol. 31, No. 1. pp. 215-226.
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