Mycoplasma mobile, a parasitic bacterium, glides on solid surfaces, such as animal cells and glass, by a special mechanism. This process is driven by the force generated through ATP hydrolysis on an internal structure. However, the spatial and temporal behaviors of the internal structures in living cells are unclear. In this study, we detected the movements of the internal structure by scanning cells immobilized on a glass substrate using high-speed atomic force microscopy (HS-AFM). By scanning the surface of a cell, we succeeded in visualizing particles, 2 nm in height and aligned mostly along the cell axis with a pitch of 31.5 nm, consistent with previously reported features based on electron microscopy. Movements of individual particles were then analyzed by HS-AFM. In the presence of sodium azide, the average speed of particle movements was reduced, suggesting that movement is linked to ATP hydrolysis. Partial inhibition of the reaction by sodium azide enabled us to analyze particle behavior in detail, showing that the particles move 9 nm right, relative to the gliding direction, and 2 nm into the cell interior in 330 ms and then return to their original position, based on ATP hydrolysis. IMPORTANCE The Mycoplasma genus contains bacteria generally parasitic to animals and plants. Some Mycoplasma species form a protrusion at a pole, bind to solid surfaces, and glide by a special mechanism linked to their infection and survival. The special machinery for gliding can be divided into surface and internal structures that have evolved from rotary motors represented by ATP synthases. This study succeeded in visualizing the real-time movements of the internal structure by scanning from the outside of the cell using an innovative high-speed atomic force microscope and then analyzing their behaviors.

Mycoplasma mobile, a parasitic bacterium, glides on solid surfaces, such as animal cells and glass by a special mechanism. This process is driven by the force generated through ATP hydrolysis on an internal structure. However, the spatial and temporal behaviors of the internal structures in living cells are unclear. In this study, we detected the movements of the internal structure by scanning cells immobilized on a glass substrate using high-speed atomic force microscopy (HS-AFM). By scanning the surface of a cell, we succeeded in visualizing particles, 2 nm in hight and aligned mostly along the cell axis with a pitch of 31.5 nm, consistent with previously reported features based on electron microscopy. Movements of individual particles were then analyzed by HS-AFM. In the presence of sodium azide, the average speed of particle movements was reduced, suggesting that movement is linked to ATP hydrolysis. Partial inhibition of the reaction by sodium azide enabled us to analyze particle behavior in detail, showing that the particles move 9 nm right, relative to the gliding direction, and 2 nm into the cell interior in 330 ms, then return to their original position, based on ATP hydrolysis.IMPORTANCEThe Mycoplasma genus contains bacteria generally parasitic to animals and plants. Some Mycoplasma species form a protrusion at a pole, bind to solid surfaces, and glide by a special mechanism linked to their infection and survival. The special machinery for gliding can be divided into surface and internal structures that have evolved from rotary motors represented by ATP synthases. This study succeeded in visualizing the real-time movements of the internal structure by scanning from the outside of the cell using an innovative high-speed atomic force microscope, and then analyzing their behaviors.

Gallium Nitride nano-particles (GaN NPs) are synthesized by a simple nitridation method. A mixture of commercially available ¢-Gallium Oxide (¢-Ga 2 O 3) and GaN powders with about 5¯m particle size was heated at temperatures ranging from 7001,000°C in an ammonia (NH 3) atmosphere for 1 h. In the powder mixture, the ¢-Ga 2 O 3 particles converted to GaN NPs agglomerates, while the GaN particles are slightly grown. When the mixture was heated in the NH 3 atmosphere at 900°C, GaN NPs varying from 30 to 50 nm and microsized GaN particles were obtained.

No abstract

Mycoplasma mobile, a pathogenic bacterium glides on solid surfaces with a unique mechanism. In the mechanism, "legs" on a cell repeatedly catch and pull sialylated oligosaccharides on host cells. The force for gliding is generated on an internal structure which consists of gliding motors evolved from F-type ATPase/synthase [1]. However, the actual movement of gliding machinery has not been observed. In this study, we focused on visualizing the movement of gliding motors in living cells by high-speed AFM [2]. To prevent Mycoplasma mobile cells from the removal from the glass slide in the observation, they were fixed onto the glass slide by crosslinking with glutaraldehyde [3]. The high-speed AFM visualized particle structures in the cell, which are consistent with the gliding motors reconstructed by electron cryomicroscopy [4, 5]. The particle movements were detected when the moving frequency was reduced by sodium azide, an inhibitor of F-type ATPase/synthase. The individual particles moved about 15 nm reversibly to the left side relative to the gliding direction of cell.