Ref HAL: hal-00630757_v1
PMID 21297002
DOI: 10.1182/blood-2010-08-299883
WoS: 000289507200028
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67 Citations
Résumé:

The culminating step of the intraerythrocytic development of Plasmodium falciparum, the causative agent of malaria, is the spectacular release of multiple invasive merozoites on rupture of the infected erythrocyte membrane. This work reports for the first time that the whole process, taking place in time scales as short as 400 milliseconds, is the result of an elastic instability of the infected erythrocyte membrane. Using high-speed differential interference contrast (DIC) video microscopy and epifluorescence, we demonstrate that the release occurs in 3 main steps after osmotic swelling of the infected erythrocyte: a pore opens in similar to 100 milliseconds, ejecting 1-2 merozoites, an outward curling of the erythrocyte membrane is then observed, ending with a fast eversion of the infected erythrocyte membrane, pushing the parasites forward. It is noteworthy that this last step shows slight differences when infected erythrocytes are adhering. We rationalize our observations by considering that during the parasite development, the infected erythrocyte membrane acquires a spontaneous curvature and we present a subsequent model describing the dynamics of the curling rim. Our results show that sequential erythrocyte membrane curling and eversion is necessary for the parasite efficient angular dispersion and might be biologically essential for fast and numerous invasions of new erythrocytes. (Blood. 2011;117(15):4118-4124)

Ref HAL: hal-00677371_v1
DOI: 10.1039/c1sm05239j
WoS: 000290227400006
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124 Citations
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We report on a continuous droplet interface crossing encapsulation (cDICE) technique for the high-yield production of microscopic vesicles tunable in size and content. Overcoming some of the current technique limitations, such a simple setup has a great potential in various fields from encapsulation to the design of biomimetic cells and artificial tissues.

Résumé:

Fabrication of vesicles, a close membrane made of an amphiphile bilayer, has great potentiality for encapsulation and controlled release in chemical, food or biomedical industries but also from a more fundamental point of view for the design of biomimetic objects. Methods based on lipid film hydratation1, inverse emulsion techniques2 and more recently microfluidic techniques such as double emulsion3 or jetting4 method are limited either by a low yield, a low reproducibility, a poor control on the size, or by the presence of remaining solvent or defects. We propose a fast and robust method5 easy to implement: Continuous droplet interface crossing encapsulation (cDICE), that allows the production of defect-free vesicles at high-yield with a control in size and content. The vesicles have controlled bilayer composition with a polydispersity in size lower than 11%. we have shown that solutions as diverse as actin, cells, micrometric colloids, protein and high ionic strength solutions can easily be encapsulated using this process. By adjusting the parameters of our set-up, we are able to produce vesicles in the range 4-100 µm in diameter, stable for weeks. We believe this method open new perspectives for the design of biomimetic systems and even artificial tissues. [1] M. I. Angelova and D. S. Dimitrov, Faraday Discuss., 1986, 81, 303. [2] S. Pautot, B. J. Frisken and D. A. Weitz, Langmuir, 2003, 19, 28702879; S. Pautot, B. J. Frisken and D. A. Weitz, Proc. Natl. Acad. Sci. U. S. A., 2003, 100, 10718. [3] H. C. Shum, D. Lee, I. Yoon, T. Kodger and D. A. Weitz, Langmuir, 2008, 24, 7651. [4] J. C. Stachowiak, D. L. Richmond, T. H. Li, A. P. Liu, S. H. Parekh and D. A. Fletcher, Proc. Natl. Acad. Sci. U. S. A., 2008, 105, 4697. [5] M. Abkarian, E. Loiseau and G. Massiera, Soft Matter, 2011, DOI: 10.1039/c1sm05239j.

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Ref HAL: hal-00538841_v1
Ref Arxiv: 1011.6081
DOI: 10.1039/b925373d
WoS: 000277031300016
Ref. & Cit.: NASA ADS
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7 Citations
Résumé:

We have used an original analysis of reflection interference contrast microscopy (RICM) to detect an ultra-weak specific interaction between a glycolipid vesicle and a lectin-coated substrate. The membrane height fluctuations in the contact zone are observed with a high illumination aperture; the membrane profile and the membrane-substrate distance are quantitatively determined using the new analysis, which accounts for multiple interfaces and multiple incidence rays. We showed that this refined version of RICM theory is necessary, specifically in the case of intermediate membranesubstrate distance (30 nm) and helped to discriminate between the ultra-weak interaction and pure gravitational sedimentation

Ref HAL: hal-00321742_v1
PMID 32900076
DOI: 10.1039/b700550d
WoS: 000247367400007
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25 Citations
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We show the existence of a flow at the surface of strongly adhering giant lipid vesicles submitted to an external shear flow. The surface flow is divided into two symmetric quadrants and presents two stagnation points (SP) on each side of the vesicle meridian plane. The position of these stagnation points depends strongly on the adhesion strength, characterized by the ratio of the contact zone diameter to the vesicle diameter. Contrary to the case of non-adhesive vesicles, streamlines do not lie in the shear plane. By avoiding the motionless contact zone, streamlines result in three-dimensional paths, strongly asymmetric away from the SP. Additional shearing dissipation may occur on the membrane surface as we observed that the mean rotational velocity of the membrane increases towards the vesicle SP, and is mainly determined by the adhesion induced vesicle shape.