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Biochim Biophys Acta. 2016 Nov;1858(11):2625-2635. doi: 10.1016/j.bbamem.2016.07.017. Epub 2016 Jul 30.

Spectral phasor analysis of LAURDAN fluorescence in live A549 lung cells to study the hydration and time evolution of intracellular lamellar body-like structures.

Author information

1
Área de Investigación Respiratoria, Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Uruguay; Unidad de Bioquímica y Proteómica Analítica, Institut Pasteur de Montevideo, Uruguay; Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California at Irvine, Irvine, CA, USA. Electronic address: lmalacrida@hc.edu.uy.
2
Unidad de Biología Celular, Institut Pasteur de Montevideo, Uruguay.
3
Área de Investigación Respiratoria, Departamento de Fisiopatología, Hospital de Clínicas, Facultad de Medicina, Universidad de la República, Uruguay.
4
Laboratory for Fluorescence Dynamics, Biomedical Engineering Department, University of California at Irvine, Irvine, CA, USA.
5
MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, Odense M, Denmark. Electronic address: bagatolli@memphys.sdu.dk.

Abstract

Using LAURDAN spectral imaging and spectral phasor analysis we concurrently studied the growth and hydration state of subcellular organelles (lamellar body-like, LB-like) from live A549 lung cancer cells at different post-confluence days. Our results reveal a time dependent two-step process governing the size and hydration of these intracellular LB-like structures. Specifically, a first step (days 1 to 7) is characterized by an increase in their size, followed by a second one (days 7 to 14) where the organelles display a decrease in their global hydration properties. Interestingly, our results also show that their hydration properties significantly differ from those observed in well-characterized artificial lamellar model membranes, challenging the notion that a pure lamellar membrane organization is present in these organelles at intracellular conditions. Finally, these LB-like structures show a significant increase in their hydration state upon secretion, suggesting a relevant role of entropy during this process.

KEYWORDS:

LAURDAN; Lamellar bodies; Macromolecular crowding; Membrane biophysics; Microscopic imaging; Spectral phasor

PMID:
27480804
PMCID:
PMC5045802
DOI:
10.1016/j.bbamem.2016.07.017
[Indexed for MEDLINE]
Free PMC Article

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