Changes in the Elastic Properties of Cholinergic Synaptic Vesicles as Measured by Atomic Force Microscopy

Abstract

Cholinergic synaptic vesicles from Torpedo californica have been probed with the atomic force microscope in aqueous buffers to map and measure their elastic properties. Elastic properties were mapped with a new atomic force microscope technique known as force mapping. Force mapping of vesicles showed that the centers of the vesicles are harder or stiffer than the peripheral areas in the three buffers that were investigated. These were an isoosmotic buffer, a hypoosmotic buffer, and an isoosmotic buffer with 5 mM CaCl2 added. The hardness of the vesicular centers was quantified by calculation of the elastic modulus. Elastic moduli were in the range of 2-13 x 10(5) Pa. Vesicular centers were hardest in calcium-containing buffer and softest in isoosmotic buffer. Hypotheses are presented for the composition and function of the hard centers.

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…This was applied to synaptic vesicles from Torpedo californica [1206], M. gryphiswaldense bacteria [1207] and oocysts of C. parvum [954].…”

Effect of chain lengths of PEO–PPO–PEO on small unilamellar liposome morphology and stability: an AFM investigation

“…The data analysis has been described elsewhere [17] and will be briefly summarized here. Force curve data was fitted to the Hertz contact model by assuming a spherical shape for the tip [17,26].…”

“…Force curve data was fitted to the Hertz contact model by assuming a spherical shape for the tip [17,26]. The indentation, δ, from the difference between the cantilever distance …”

“…In order to elucidate the effects of PEO and PPO chains on stability enhancement, a more quantitative approach is desired to measure the micromechanical properties of the individual liposome. AFM force plots were used to investigate the micromechanical properties of small vesicles on a mica surface [17][18][19].…”

Probing nanomechanical properties from biomolecules to living cells

“…This fundamental physiological process appeared at an early stage of evolution, and most of the molecular mechanisms that are manifested in simple unicellular organisms, such as yeast, have been conserved in more complex systems, such as the mammalian brain [10]. The mechanical properties of neurotransmitter-secreting vesicles were investigated by Laney et al [54] in 1997. It has been assumed that the stiffness of vesicles determines the mechanism of exocytosis.…”