Ishida M, Allen R D, Fok A K
Department of Physiology, Mie University School of Medicine, Tsu, Japan.
J Eukaryot Microbiol. 2001 Nov-Dec;48(6):640-6. doi: 10.1111/j.1550-7408.2001.tb00203.x.
The roles of somatic and oral cilia and solid particles during digestive vacuole (DV) formation in Paramecium multimicronucleatum were investigated using video-enhanced and immunofluorescence microscopy. Membrane incorporation into DVs was found to increase linearly with increasing particle concentration. The rate of discoidal vesicle transport to the cytopharynx was not affected by particles, showing that particles are not required for membrane trafficking to the cytopharynx. However, the presence of particles leads to an increased membrane fusion between the cytopharyngeal membrane and the discoidal vesicles. When live cells lost their somatic cilia on the left-ventral side anterior to the oral region due to deciliation, membrane incorporation into newly formed DVs was strongly inhibited. Using video-enhanced microscopy, latex beads were seen to be loaded along the quadrulus on the dorsal surface of the buccal cavity, but few beads were seen next to the dorsal and ventral peniculi. Particle sequestration into a pre-formed nascent digestive vacuole (NDV) was studied in Triton X-100-permeabilized cells whose ciliary beating was reactivated by the addition of Mg-ATP. Both beat frequency and the percentage of cells containing bead-labeled NDV were dependent on the Mg-ATP concentration: the higher the beat frequency, the higher the percentage of cells with a bead-labeled NDV. These results suggest that ciliary beating is probably the only mechanism required for particle accumulation in the NDV, while a coordinated beating of the somatic cilia on the left-ventral side anterior to the oral region as well as the quadrulus moves particles into the NDV. The beating of the peniculi may somehow prevent the backward flow of particles out of the NDV.
利用视频增强显微镜和免疫荧光显微镜，研究了多核草履虫消化泡（DV）形成过程中体细胞纤毛、口纤毛和固体颗粒的作用。发现膜掺入消化泡的量随颗粒浓度的增加呈线性增加。盘状小泡向胞咽的运输速率不受颗粒影响，表明颗粒不是膜运输到胞咽所必需的。然而，颗粒的存在会导致胞咽膜与盘状小泡之间的膜融合增加。当活细胞由于去纤毛作用而在口区前方左侧腹侧失去体细胞纤毛时，新形成的消化泡中的膜掺入受到强烈抑制。通过视频增强显微镜观察到，乳胶珠沿着口腔背表面的四边形排列，但在背侧和腹侧小膜附近几乎看不到珠子。在经Triton X-100通透处理的细胞中研究了颗粒隔离到预先形成的新生消化泡（NDV）中的情况，这些细胞的纤毛摆动通过添加Mg-ATP得以重新激活。纤毛摆动频率和含有珠子标记的新生消化泡的细胞百分比均取决于Mg-ATP浓度：摆动频率越高，含有珠子标记的新生消化泡的细胞百分比越高。这些结果表明，纤毛摆动可能是颗粒在新生消化泡中积累所需的唯一机制，而口区前方左侧腹侧的体细胞纤毛以及四边形结构的协同摆动将颗粒移入新生消化泡。小膜的摆动可能以某种方式防止颗粒从新生消化泡中倒流出来。
