1,720,965 research outputs found
The photosensory transduction in Halobacterium salinarium: An overview of behavioural and biophysical data
No full textPhotosensors and phototransduction models in Halobacterium salinarum: a lesson from behavioural studies
No full textColor-specific conditioning effects due to both orange and blue stimuli are observed in a Halobacterium salinarum strain devoid of putative methylatable sites on HtrI
No full textIs Sb510 the signalling state for photoresponses to blue light stimuli in Halobacterium salinarum?
No full textPhotoresponses of Halobacterium salinarum to repetitive pulse stimuli
No full textAbstractHalobacterium salinarum cells from 3-day-old cultures have been stimulated with different patterns of repetitive pulse stimuli. A short train of 0.6-s orange light pulses with a 4-s period resulted in reversal peaks of increasing intensity. The reverse occurred when blue light pulses were delivered as a finite train: with a 3-s period, the response declined in sequence from the first to the last pulse. To evaluate the response of the system under steady-state conditions of stimulation, continuous trains of pulses were also applied; whereas blue light always produced a sharply peaked response immediately after each pulse, orange pulses resulted in a declining peak of reversals that lasted until the subsequent pulse. An attempt to account for these results in terms of current excitation/adaptation models shows that additional mechanisms appear to be at work in this transduction chain
Competition-integration of blue and orange stimuli in Halobacterium salinarum cannot occur solely in SRI photoreceptor
No full textAbstractExperiments on the integration of blue and orange stimuli in Halobacterium salinarum were performed by using different combinations of blue and orange steps. The results show that the prevalence of the blue stimulus over the orange one depends on both the blue and the orange light intensities. A quantitative analysis of the current hypotheses on the phototransduction of orange and UV-blue light stimuli is presented, showing that the balancing between the two antagonistic stimuli should depend only on the intensity of the blue stimulus and not on that of the orange one, provided that the combination of the two stimuli occurs linearly at the photoreceptor stage. We conclude that blue and orange stimuli elicit distinct intracellular signals whose integration occurs downstream of the photoreceptor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
NORMAL AND LATERAL FORCES IN SCANNING FORCE MICROSCOPY
No full textWith an atomic force/friction force microscope operating in the constant force mode and with an optical lever technique as a deflection sensor, we have investigated the total force acting on the cantilever tip during the raster scanning of the sample surface. A model including the normal and lateral components of the force has been worked out. The normal force is related to the cantilever loading. The lateral force has two components, dissipative and nondissipative, having opposite symmetry with respect to the scanning direction. Within our model, the nondissipative component, which is related to the topography, can be distinguished from the friction component in two different ways, both leading to ''pure friction'' images. The first method is based on the comparison of two images acquired in the forward and backward scanning direction, respectively. The second method is based on the comparison of the topographic and lateral force images acquired in the same scanning direction. This latter way does not need correction for the nonlinear behavior of the piezoelectric transducer. Results from various samples are reporte
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