Biophysical studies of pigment transport in frog melanophores: impedance measurements and advanced microscopy analyses
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Small proteins, other molecules and large organelles are frequently transported from one location to another within cells. These transports employ cytoskeletal networks and enable cells to maintain regions with different functions and attain an asymmetrical shape.
The aim of this work was to explore biophysical methods for monitoring intracellular transport processes and associated structural changes. For these studies we have used pigment cells, melanophores, from the African clawed frog Xenopus laevis. In response to external stimuli, these cells can change colour by redistributing pigment granules in the cytoplasm.
Transparent "cell clinics" equipped with gold electrodes were developed for impedance studies. The results show that impedance measurements at different frequencies not only can be used to monitor cell attachment and spreading, but also events like pigment aggregation. Significant F-actin breakdown and a cell area decrease may explain the impedance decrease seen during latrunculin-induced aggregation. In aggregation induced by melatonin there was, however, a small increase of the cell area, no F-actin breakdown and still lowered impedance, indicating that some other, likely intracellular mechanism is involved. In addition, confocal laser scanning microscopy (CLSM) studies showed that aggregation was associated with an increase in the cell height, more prominent for latrunculin than for melatonin. This height increase did not seem to involve influx of water through aquaporin channels at the cell membrane, or newly formed or remodelled microtubules in the cells.
Besides impedance measurements, Image Correlation Spectroscopy (ICS) was applied to analyse pigment aggregation. The study shows for the first time that ICS can be used to analyse aggregation of non-fluorescent particles and suggests that the method may provide new information on the state of aggregation of granules in pigment cells.
Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2003. , 58 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 803
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-26657Local ID: 11222ISBN: 91-7373-491-8OAI: oai:DiVA.org:liu-26657DiVA: diva2:247206
2003-09-26, Victoriasalen, Hälsouniversitetet, Linköping, 09:00 (Swedish)
Rorsman, Patrik, Professor
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