Actas de congresos
Leishmania Amazonensis Chemotaxis Under Glucose Gradient Studied By The Strength And Directionality Of Forces Measured With Optical Tweezers
Registro en:
0819465542; 9780819465542
Progress In Biomedical Optics And Imaging - Proceedings Of Spie. , v. 6441, n. , p. - , 2007.
16057422
10.1117/12.701196
2-s2.0-34247344560
Autor
De Ysasa Pozzo L.
Fontes A.
De Thomaz A.A.
Barbosa L.C.
Ayres D.C.
Giorgio S.
Cesar C.L.
Institución
Resumen
Chemotaxis is the mechanism microorganisms use to sense the environment surrounding them and to direct their movement towards attractive, or away from the repellent, chemicals. The biochemical sensing is almost the only way for communication between unicellular organisms. Prokaryote and Eukaryote chemotaxis has been mechanically studied mainly by observing the directionality and timing of the microorganisms movements subjected to a chemical gradient, but not through the directionality and strength of the forces it generates. To observe the vector force of microorganisms under a chemical gradient we developed a system composed of two large chambers connected by a tiny duct capable to keep the chemical gradient constant for more than ten hours. We also used the displacements of a microsphere trapped in an Optical Tweezers as the force transducer to measure the direction and the strength of the propulsion forces of flagellum of the microorganism under several gradient conditions. A 9μm diameter microsphere particle was trapped with a Nd:YAG laser and its movement was measured through the light scattered focused on a quadrant detector. We observed the behavior of the protozoa Leishmania amazonensis (eukaryote) under several glucose gradients. This protozoa senses the gradient around it by swimming in circles for three to five times following by tumbling, and not by the typical straight swimming/tumbling of bacteria. Our results also suggest that force direction and strength are also used to control its movement, not only the timing of swimming/tumbling, because we observed a higher force strength clearly directed towards the glucose gradient. 6441
Law, A.M.J., Aitken, M.D., Continuous-flow capillary assay for measuring bacterial chemotaxi (2005) Applied And Environmental Microbiology, 71 (6), pp. 3137-3143 Khan, S., Jain, S., Reid, G.P., Trentham, D.R., The fast tumble signal in bacterial chemotaxis (2004) Biophysical Journal, 86 (6), pp. 4049-4058 Neuman, K.C., Chadd, E.H., Liou, G.F., Bergman, K., Block, S.M., Characterization of photodamage to Escherichia coli in optical traps (1999) Biophysical Journal, 77 (5), pp. 2856-2863 Who, (2002) World Health Organization Soares, R.P.P., Turco, S.J., Lutzomya longipalpis (Díptera: Psychodidae: Phlebotominae): a review (2003) An Acad Bras Cienc, 75, pp. 301-330 Rice, S.E., Purcell, T.J., Spudich, J.A., Building and using optical traps to study properties of molecular motors (2003) Biophotonics, PT B, 361, pp. 112-133 Rohrbach, A., Stelzer, E.H.K., Three-dimensional position detection of optically trapped dielectric particles (2002) Journal Of Applied Physics, 91 (8), pp. 5474-5488 Gittes, F., Schmidt, C.F., Interference model for back-focal-plane displacement detection in optical tweezers (1998) Optics Letters, 23 (1), pp. 7-9 Allersma, M.W., Gittes, F., deCastro, M.J., Stewart, R.J., Schmidt, C.F., Two-dimensional tracking of ncd motility by back focal plane interferometry (1998) Biophysical Journal, 74 (2), pp. 1074-1085