Mechanical properties of membranes from spheroplast using optical tweezers

COLQUE, A., GONZALEZ MONTORO, M.A., VALDEZ-TAUBAS, J. Y N. WILKE

Carlos Paz

Congreso; 'XLII Reunión Anual de la Sociedad Argentina de Biofísica; 2013

Laser tweezers and optical microscopy have been used for the determination of the rheological properties of model biomembranes1 and of membranes of mammal cells2. Here, we used the technique to explore the deformability of membranes of spheroplast of yeast Saccharomyces cerevisiae. It was reported that the shear viscosity of this membrane is very different from mammal cells but the out-of-plane deformability has not been studied yet. The wall of Saccharomyces cerevisiae cells was digested with zymoliase and 200 µL of a suspension of spheroplasts were placed on a glass cover-slide previously treated with piranha solution for 2 h and poly-lysine in buffer borate overnight. A 10µL-drop of an aqueous solution of micro-spheres (anionic, 3 µm diameter or cationic, 1 µm diameter) was added to the spheroplasts. After an hour, some beads were attached to the spheroplast surface, permitting to catch the bead with the optical trap and move it apart from the spheroplast. This movement generated a membrane nanotube between the cell and the bead, which allowed to test the membrane deformability, by tracking the bead position relative to the spheroplast in time after the trap was turned off. The nanotube relaxation process suggested that the spheroplast membrane was more elastic than the membrane of mammal cells. References: 1- Sorre B et al.PNAS. 2012. 173-178. 2- Pascoal P. et al. Lab Chip. 2010. 2235-2241. 3- Valdez-Taubas J. et al. Curr. Biol 2003 1636-1640.