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We investigate a motion of diatom cells stimulated by a halogen lamp irradiation. Diatom cells are single-celled organisms which have chloroplast. Chloroplast contains photosynthetic pigment which absorbs blue light (wave length of the light is 400 nm–450 nm) and red one (650 nm–700 nm). Light intensity of the halogen lamp is fixed about 500 Lx during the experiment. We used colored films to cut the blue or red light and observed motion of diatom cells by using the optical microscope. We found that the speed of diatom cells decreases when the colored film is inserted, and it increases after ejecting the film. It is noted that the light intensity is constant during the experiment, which means that we change wave length of the irradiated light. Our results show that the average speed of diatom cells is influenced by not the light intensity but the wave length of the light. [ABSTRACT FROM AUTHOR]

In this study, we used a microchamber to observe and analyze the gliding phenomenon of Navicula pavillardii diatom cells at different temperatures. The temperature of the culture medium was varied from 17.0 to 30.0 °C to examine the effect of temperature on diatom movement. Movement of each cell at different temperatures was monitored by use of an inverted optical microscope and continuously recorded as video data, from which the velocities of each cell were calculated, by using dedicated software to perform two-dimensional trajectory analysis. The velocities of the same cell at different temperatures were thereby successfully compared. The results showed that the change in cell velocity was insignificant when the temperature was increased from 17.0 to 25.0 °C. When the temperature was increased from 17.0 to 27.5 °C, non-uniformly disrupted cell movement was observed. When the temperature was further increased to 30.0 °C, cell movement was clearly inhibited. By use of single-cell analysis, the effects of the temperature increases on diatom movement were successfully evaluated. Finally, we characterized the experimental data by performing t tests to evaluate the effects of variations of the movement of individual cells on the data analysis. [ABSTRACT FROM AUTHOR]

We propose a new technique for quantitative trajectory analysis of gliding phenomenon of Navicula pavillardii (NP) and Seminavis robusta (SR) diatom cells by single cell observation using a glass microchamber in this short technical note. Two-dimensional trajectory analysis of cell movements was used to determine the angular velocity, velocity, and migration distances of the diatom movement. Based on the trajectory analysis, we found that asymmetrically shaped SR had a larger angular velocity with large fluctuations compared to symmetrically shaped NP, although the velocity of SR was less than that of NP. It suggests that lateral frictional force in a culture medium is an important factor for diatom movements. Our results revealed that the single cell observation using a glass microchamber is effective on quantitative analysis of angular velocity of diatom gliding. [ABSTRACT FROM AUTHOR]

Diatoms are one of the major photosynthetic planktons. Here, we studied movements of aqueous suspensions of diatoms using a home-made 'tumbled' optical microscope system. The usual inverted optical microscope was reoriented using a homemade microscope stand so that the vertical sample stage contacted the surface. To observe the intrinsic sinking phenomenon of individual Navicula sp. cells, which have slender bodies, a homemade microchamber (1 mm3) was employed. Most of the cells uniformly sunk with a velocity of 2 to 14 μm/s. Automatic and manual two points trajectory analyses were carried out. The manual analysis was able to assess the rotation of cells. The novel methods provide new information about cell movements in aqueous systems that could not be obtained using conventional methods. Unlabelled Image • We observed sinking of diatom cells a home-made 'tumbled' optical microscope. • Automatic centroid mode analysis well revealed trajectories of hundreds of cells. • Manual two points analysis was effective on analyzing rotation of individual cells in water. [ABSTRACT FROM AUTHOR]