Satoshi Ogihara

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During inversion of a Volvox embryo, a series of cell shape changes causes the multicellular sheet to bend outward, and propagation of the bend from the anterior to the posterior pole eventually results in an inside-out spherical sheet of cells. We use fluorescent and electron microscopy to study the behavior of the cytoskeleton in cells undergoing shape(More)
The cell cortex of Dictyostelium amebae contains an actin-rich cytoplasmic matrix. Changes in geometry of this matrix are believed to regulate protrusive activity and motility of the cell cortex. Two actin-binding proteins (120,000 and 95,000 daltons [120K and 95K]) are present in the cell cortex, and their properties, many of which are described here for(More)
In Volvox carteri adults, reproductive cells called gonidia are enclosed within a spherical monolayer of biflagellate somatic cells. Embryos must "invert" (turn inside out) to achieve this configuration, however, because at the end of cleavage the gonidia are on the outside and the flagellar ends of all somatic cells point inward. Generation of a bend(More)
Polarized epithelial cells develop and maintain distinct apical and basolateral surface domains despite a continuous flux of membranes between these domains. The Na(+)/H(+)exchanger NHE6 localizes to endosomes but its function is unknown. Here, we demonstrate that polarized hepatoma HepG2 cells express an NHE6.1 variant that localizes to recycling endosomes(More)
We observed the fine structure of myosin filament bundles in 10 mM MgCl2 and studied the effects of light chain phosphorylation on it by electron microscopy. In the filament bundles of dephosphorylated myosin in the presence of ATP, we found a striation pattern of 13.4 nm periodicity running perpendicularly to the long axis of the filaments. However, we did(More)
Exocytosis has been proposed to participate in the formation of pseudopods. Using video-enhanced microscopy, we directly visualized exocytosis of single vesicles in living Physarum plasmodia migrating on a substrate. Vesicles containing slime, the plasmodial extracellular matrix, of approximately 3.5 microm in diameter, shrank at the cell periphery at the(More)
1. The actin-activated Mg2+-ATPase activity of gizzard HMM increased in proportion to the square of the extent of LC phosphorylation. This result indicates that the LCs of HMM are randomly phosphorylated, and the phosphorylation of both heads of HMM is required for the activation of HMM Mg2+-ATPase by F-actin. 2. In 75 mM KCl, the Mg2+-ATPase activity of(More)
Helicobacter pylori (H. pylori), the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane(More)
The ultrastructural changes in electropermeabilized bovine platelets that accompany the Ca2(+)-induced secretion of serotonin were investigated in ultra-thin sections of chemically fixed cells. Such preparations permitted us to study both the localization of and the structures associated with serotonin-containing dense granules. Localization of dense(More)
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