Publication details

Discrete Fourier transform-based analysis of HeLa cell microtubules after ultrasonic exposure



Year of publication 2005
Type Article in Periodical
Magazine / Source Microscopy Reasearch Technique
MU Faculty or unit

Faculty of Medicine

Field Biophysics
Keywords cytoskeleton; microtubules; immunofluorescence; FFT analysis; ultrasound; image analysis
Description Cytoskeletal structures can be affected by ultrasound. We exposed HeLa cells to continuous ultrasound (1 MHz, 1 and 2, 10 min. at 37 C). The microtubules were detected by the monoclonal antibody TU-01/SwAM/FITC, observed in a fluorescence microscope and photographed digitally. The images were processed by FFT magic software. The structure analysis is based on frequency domain filtering using discrete Fourier transform. We tried to design filters to extract information describing best the structural changes. The properties of the filter can be enhanced by direction filtering, i.e., extraction of a symmetric angular segment in the frequency domain centred on a zero frequency. The final image is a normalised sum of inverse FFTs of such segmented spectra. The method yielded the ratio of the area of microtubules to the total cell area. Assuming that the image background intensity is constant, we can use thresholding to detect areas occupied by the cells. The information about the area of the microtubules is contained in a wide range of higher intensities. Therefore, we use a gamma correction. The area occupied by microtubules is then considered an area with intensities above the selected threshold. There were tested three different filters. The mathematical method chosen seems sensitive enough for quantitative assessment of changes of the microtubular network.
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