| Poster, Friday, 19:00 |
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| Biomechanical Features of
the Cell Nucleus During Optical Stretching
Enrico Warmt, Tobias Kießling,
Anatol Fritsch, Roland Stange, Josef A. Käs
University of Leipzig, Faculty of
Physics and Earth Sciences, Institute of Experimental Physics I, Soft Matter
Physics Division, Linnéstraße 5, 04103 Leipzig, Germany |
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The deformation of cells in optical stretcher experiments is considered
to be caused exclusively by the deformation of the cellular cytoskeleton.
However, the visual appearance of certain cell types during the stretching
process implicates events taking place in the cell organelles, especially
the cell nucleus. To obtain a more detailed view into the cell we dyed
the nucleus in different cell lines and stretched many cells to examine
the behavior of the nucleus. At a certain laser power, we observe an abrupt
restructuring of the nucleus of MCF-7 cells. This restructuring is irreversible
and does not occur during a second stretch of the same cell. Interestingly,
the intensity of the restructuring differs between cell lines in a highly
reproducible way: While MCF-7 and HMEC show a significant restructuring,
less or even no restructuring is observed on MDA-MB-231, MDA-MB-436 and
MCF-10A cells. By controlling the ambient temperature, we show that restructuring
is triggered by a laser-induced increase in temperature during measurement.
The underlying physical processes and the origin of the variations among
cell lines has to be clarified.
Fig. 1: Deformation curve of a nucleus: Increasing the laser
power linearly from 200 mW after one second to 2000 mW after nine seconds.
First, the nucleus contracts in laser direction, after that it extends
in the same way.
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