Importance of observation interval in two-dimensional video analysis of individual diatom cells.

The effect of the observation interval on two-dimensional trajectory analysis of motility of individual diatom cells of Navicula sp. was studied by comparing thinned-out observation data. The trajectory of cell movement was visualized accurately even after thinning the data interval. However, the analysis of velocity fluctuations of individual cells was found to be significantly affected by the data interval. Reproducibility of the results was guaranteed by analyzing many independent cells. In addition, comparison between automatic and manual determination of cell positions proved that automatic determination was a reliable process. Our data indicated that two-dimensional trajectory analysis using a computer can be a powerful technique to study diatom locomotion.