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An electrode system is described for the near-simultaneous application and measurement of translational, levitational and rotational forces induced by AC electric fields, and this has been used to investigate the differences in the AC electrodynamics of viable and non-viable yeast cells. A new approach to the theoretical modelling of the experimental data(More)
We used electrorotation measurements to investigate alterations in the plasma membranes of DS19 murine erythroleukaemia cells that accompanied erythropoietic differentiation induced by hexamethylene bisacetamide (HMBA). Following 3 days of HMBA treatment, the mean cell membrane specific capacitance determined from electrorotation spectra of individual,(More)
Vibrations in microtubules and actin filaments are analysed using amethod similar to that employed for description of lattice vibrationsin solid state physics. The derived dispersion relations show thatvibrations in microtubules can have optical and acoustical branches.The highest frequency of vibrations in microtubules and in actinfilaments is of the order(More)
The determination of complete electrorotation spectra of living cells has been made possible by the development of a quadrature generator and an electrode assembly that span the frequency range between 100 Hz and 1.6 GHz. Multiple spectra of single cells of the yeast Saccharomyces cerevisiae have been measured at different medium conductivities ranging from(More)
So far, electrorotation and its application to the determination of single cell properties have been limited to eukaryotes. Here an experimental system is described that allows the recording of electrorotation spectra of single bacterial cells. The small physical dimensions of the developed measuring chamber combined with a single frame video analysis made(More)
Electrorotational spectra of yeast cells, Saccharomyces cerevisiae strain R XII, were measured over a frequency range of nearly 7 decades. The physical properties of distinct cell parts were simultaneously determined for individual cells by comparison with an electrical two-shell model: The conductivity of the cytoplasm, cell wall and cytoplasmic membrane(More)
Electrorotation (ROT) spectra of Friend murine erythroleukaemia DS19 cells were measured in the frequency range 10 kHz-100 MHz as a function of suspension osmolality and cell differentiation treatment with hexamethylene bisacetamide (HMBA). A minimization program was employed to curve-fit the measured spectra using a single-shell dielectric model, allowing(More)
A widespread use of electrorotation for the determination of cellular and subcellular properties has been hindered so far by the need for manual recording of cell movements. Therefore a system has been developed that allows the automatic collection of electrorotation spectra of single cells in real time. It employs a hardware based registration of image(More)
Rotation of living and dead yeast cells with and without buds was examined in rotating electric fields through a frequency range of 90 Hz to 140 MHz. For living yeast maximum rotation was observed in co-field direction at 30 MHz as predicted from model calculations, but with an unexpected sharp second resonance at 80 MHz for nonbudding cells. Also in the(More)
The Portuguese dogfish Centroscymnus coelolepis is a deepwater squaloid shark with a wide distribution and is also an important fishing resource in parts of its range. Despite concerns about the species’ sustainability, current fisheries management measures have been implemented without a good understanding of the stock structure. The assessment of the(More)
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