Sensory Transduction in Halobacterium halobium: Retinal Protein Pigment Controls UV-Induced Behavioral Response

Dencher, Norbert A.; Hildebrand, Eilo

doi:10.1515/znc-1979-9-1030

Cited by 54 publications

(36 citation statements)

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“…This light intensity is comparable with or lower than the intensities used by other workers (3,11,12,22,23).…”

Section: Methodssupporting

confidence: 68%

“…Halobacteria are attracted by long-wavelength and visible light and repelled by short-wavelength, visible, and near-UV light (3,18). The resulting accumulation or depletion of cells in the measuring spot can be observed directly ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Complete action spectra are much more easily obtained by monitoring changes in cell density as a function of spatial differences in light intensity and wavelength. We developed the microscopic method described here to obtain action spectra for the phototactic responses of halobacteria, which, until now, have been obtained mainly by observations of single cells (2,3,22,23) or by a very slow macroscopic technique (14). The basic technique was already used by Engelmann, the discoverer of bacterial phototaxis (6), who observed the accumulation of cells in a field of attractant light.…”

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A rapid population method for action spectra applied to Halobacterium halobium

1988

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We have developed a simple and rapid technique for measuring the action spectra for phototaxis of populations of microorganisms and applied it to halobacteria. A microscope with a dark-field condenser was used to illuminate the cell suspension in a sealed chamber with light of wavelength >750 nm; in this region of the spectrum, the halobacteria show no phototactic response. A 150-p.m spot of light from a xenon arc lamp, whose wavelength and intensity can be varied, was projected through the objective lens into the center of the dark field. The objective lens imaged this measuring spot through a 780-nm cut-off filter on an aperture in front of a photomultiplier. The intensity of the scattered 750-nm light, and therefore the photomultiplier current, is proportional to the number of cells in the measuring spot. A third lamp provided background light of variable wavelength and intensity through the dark-field condenser. To minimize secondary effects due to large changes in cell density, we recorded the initial changes in the photomultiplier current over 1 min after the actinic light had been switched on. By plotting the rate of change against wavelength, we obtained action spectra after the proper corrections for changes in light intensity with wavelength were applied and saturation effects were avoided.

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“…This light intensity is comparable with or lower than the intensities used by other workers (3,11,12,22,23).…”

Section: Methodssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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A rapid population method for action spectra applied to Halobacterium halobium

1988

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“…The addition of an uncoupler that repells H. halobium [8] caused MCP demethylation. The illumination of bacteria by green light, which is absorbed by the bacteriorhodopsin proton pump, increases the membrane potential and attracts cells via A~H +-sensing [7,8] [5,6]. It is believed that blue light absorbed by P370 causes a membrane depolarisation and the subsequent reversal of bacterial flagella [21][22][23].…”

Section: Discussionmentioning

confidence: 99%

The role of methylation in the taxis of Halobacterium halobium to light and chemo‐effectors

1982

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In Halobaeterium halobium tactic responses towards light and chemoeffectors are accompanied by changes in the methylation level of methyl-accepting chemotaxis proteins (MCP). Taxis towards green light absorbed by the bacteriorhodopsin proton pump appears to be governed by A/t H +-sensing. The addition of CCCP, an uncoupler, prevented the increase of MCP methylation in response to green light illumination, but had no effect on CH3-incorporation followed by the addition of the attractants glucose, leucine and histidine: Similarly, CCCP did not change MCP demethylation in response to blue light illumination, a repelling stimuli. The sensitivity to an uncoupler of methylation linked to AFt H+-mediated green light taxis is to be expected, while the independence of demethylation caused by the blue light of CCCP is an indication that in the latter case a specific photoreceptor governs phototaxis. Informed processing from the blue light receptor to MCP does not involve a change in the membrane potential. Halobacterium halobium photobehavior a~H+-sensing Protein methylation Blue-light taxis

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“…We postulate that the inverse responses are caused by certain properties of a cellular osciUlator for which we previously postulated a role in response regulation and sensory control in halobacteria (A. Schimz Halobacteria can sense changes in light fluence rate through membrane-bound retinal-protein complexes, and they respond with an altered pattern of behavior (2,3,12,14,15). The organisms swim by means of polarly inserted flagella in either direction of their long axis.…”

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Role of the response oscillator in inverse responses of Halobacterium halobium to weak light stimuli

Hildebrand¹,

Schimz²

1987

J Bacteriol

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(3,4,15). According to the wavelengths of maximal quantum efficiency the two sensory photosystems were called PS 565 and PS 370 (3). Recently an additional pigment which absorbs maximally around 475 nm was found to contribute to the sensitivity in the blue-UV range (17).The magnitude of the behavioral responses usually depends directly on the stimulus strength, i.e., on the increase or decrease of the fluence rate (4). Under certain conditions, however, weak attractant stimuli can lead to repellent responses and weak repellent stimuli cause attractant responses. In the present paper we describe such inverse responses. Furthermore, we discuss these phenomena in relation to a cellular oscillator for which we previously proposed a role in response regulation and sensory control in halobacteria (10, 11). MATERIALS AND METHODSBacterial strains and cultivation. Cells of Halobacterium halobium with different interval lengths between spontaneous reversals were used. Strain WS (resembles the wild type in pigment content) had the shortest intervals; R1L3 (lacks most of the carotenoids) had intervals of medium length; ET15-7 (lacks bacteriorhodopsin and carotenoids and does not respond to stimuli in the yellow-green range) had the longest intervals (5); Flx3 lacks the light energy-converting * Corresponding author. pigments bacteriorhodopsin and halorhodopsin (13). Cultivation was done as described earlier (5). Bacteria from the early stationary phase were used.It was possible to obtain cells with extremely short or long intervals from these strains by further selection. Single colonies were isolated; after growth in peptone medium, the cultures were tested for the length of spontaneous reversal intervals. The cultures with the longest intervals were directly used for experiments; cultures with short intervals were further selected for high motility on soft agar plates (15).Experimental procedure. Single cells in a population were observed through a phase-contrast microscope connected to an infrared-sensitive video system. At given delay times after a spontaneous reversal had been observed, stimuli (stepwise increase or decrease of light) were applied through the objective by an incident light illuminator.The interval length between reversals before and after the stimulus was measured with an electronic stopwatch. The response is defined as an attractant response when the interval is longer, and as a repellent response when it is shorter, than the average spontaneous interval.The wavelength of stimulating light was either 565 or 370 nm. If not otherwise noted, background light for observation was white light (>350 nm, 250 W m-2). Further details of the experimental prodecure, including light measurement, were described elsewhere (5). The temperature was 22 to 24°C. RESULTSIn most strains of H. halobium the mean interval length between spontaneous reversals is about 10 to 12 s. Some strains we used showed longer or shorter mean interval lengths. By isolation of single cells out of these populations it was possible to get r...

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Sensory Transduction in Halobacterium halobium: Retinal Protein Pigment Controls UV-Induced Behavioral Response

Cited by 54 publications

References 0 publications

A rapid population method for action spectra applied to Halobacterium halobium

A rapid population method for action spectra applied to Halobacterium halobium

The role of methylation in the taxis of Halobacterium halobium to light and chemo‐effectors

Role of the response oscillator in inverse responses of Halobacterium halobium to weak light stimuli

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