Berlin 2018 – scientific programme

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BP: Fachverband Biologische Physik

BP 15: Postersession III

BP 15.28: Poster

Tuesday, March 13, 2018, 14:00–16:00, Poster B

Assessing the Spatial Heterogeneity of Crowding in Living Cells — •Claudia Donth and Matthias Weiss — University of Bayreuth, Experimental Physics I

Although the interior of living cells consists of a plethora of unevenly distributed macromolecules and membrane-enclosed organelles covering several size ranges, cellular fluids are typically assumed to be homogeneously crowded solutions.

To explore the spatial heterogeneity of cellular fluids we used FRET, FLIM and confocal imaging as well as ratiometric confocal imaging in living cells. Based on the definition of the signal-to-noise ratio we defined the heterogeneity of an observable as the ratio of its standard deviation and its mean. By means of simulations we established the relation between the heterogeneity of crowding and the heterogeneity of emitted fluorescence intensity, allowing us to determine the local spatial heterogeneity of cellular crowding from imaging data.

Using different fluorescence markers we analyzed the spatial heterogeneity of macromolecular crowding states as well as that of the local ATP:ADP ratio. In addition to our measurements in interphase and metaphase cells we did time-lapse measurements in cells subjected to osmotic and oxidative stress as well as cells undergoing apoptosis to gain insight into possible dynamic changes of the local heterogeneity of cellular fluids.

Our results suggest a considerable spatial heterogeneity of cellular fluids with marked differences between nucleoplasm and cytoplasm that even persist after nuclear envelope breakdown.