Studies on intra- and extracellular calcium translocation during the gravitropic response of plant roots

神奈川大

Water Stress-induced Ultrastructural Changes of Leaf tissues and Cells in the Ice Plant, Mesembryanthemum crystallinum L.

A facultative halophyte ice plant, Mesembryanthemum crystallinum L., switchs over from C_3 photosynthesis to Crassulacean acid metabolism (CAM) under environmental stress, such as water stress (osmotic stress or ionic stress). The ultrastructural changes of tissues and cells during the metabolic switch were examined in common ice plants cultured hydroponically with 400 mM NaCl. To define the stress-induced metabolic switch, the concentration of malate was measured in well expanded green leaves kept in the light and dark. The concentration was significantly higher in leaves kept in the dark than in the light, indicating CAM induction by water stress in the ice plant. The leaves of stress-induced CAM plants and unstressed plants were fixed chemically by conventional methods, and ultrathin sections were examined with a light microscope and an electron microscope. In contrast with those found in unstressed plants, in stress-induced CAM plants, epidermal bladder cells were well developed, mesophyll cells changed to small and round in shape, and the intercellular spaces became remarkably narrow. These changes may be caused directly by waterstress. Furthermore, in mesophyll cells, the chloroplasts contained conspicuously swelled thylakoids and a few small starch grains. These structural changes in chloroplasts may reflect the metabolic switch induced by water stress

Pigment Changes and Ultrastructural Morphogenesis of Chromoplasts during Fruit Ripening of Pimentos

The correlative change of pigments with chromoplast morphogenesis in the pericarpof yellow and red pimentos during fruit ripening was examined by pigment spectrophotometryand electronmicrosopy. The metamorphosis of plastids, chloroplasts to chromoplasts, occurredwith the decrease of chlorophyll contents and the appearance of newly synthesized carotenoids,chloroxanthin in yellow pimentos and possibly capsanthin and/or capsorubin in red pimentos.As ripening proceeded, in plastids, plastoglobuli increased in both number and size, in contrastwith the degradation of grana-stack and the fragmentation of stromal thylakoids. The plastidsof yellow-ripe fruit pericarps contained exclusively plastoglobuli of various sizes at the center ofstroma, indicating G (globular)-type chromoplasts, while the plastids of red-ripe fruit pericarpsincluded a few enlarged plastoglobuli and electron-dense inclusions of various configurations,which possibly transformed from plastoglobuli to finally form needle-shaped carotenoidcrystalloids. They were determined as an intermediate-type between G-type and F (filament)-typechromoplasts, and it was reconfirmed that, during chromoplast maturation, needle-shapedcarotenoid crystalloids are formed by the elongation of enlarged plastoglobuli, concomitant withthe increase of cartotenoid contents

SLPI facilitates cell migration by regulating lamellipodia/ruffles and desmosomes, in which Galectin4 plays an important role

To elucidate the underlying mechanism of secretory leukocyte protease inhibitor (SLPI)-induced cell migration, we compared SLPI-deleted human gingival carcinoma Ca9-22 (Delta SLPI) cells and original (wild-type: wt) Ca9-22 cells using several microscopic imaging methods and gene expression analysis. Our results indicated reduced migration of Delta SLPI cells compared to wtCa9-22 cells. The lamellipodia/dorsal ruffles were smaller and moved slower in Delta SLPI cells compared to wtCa9-22 cells. Furthermore, well-developed intermediate filament bundles were observed at the desmosome junction of Delta SLPI cells. In addition,Galectin4was strongly expressed in Delta SLPI cells, and its forced expression suppressed migration of wtCa9-22 cells. Taken together, SLPI facilitates cell migration by regulating lamellipodia/ruffles and desmosomes, in which Galectin4 plays an important role

SLPI facilitates cell migration by regulating lamellipodia/ruffles and desmosomes, in which Galectin4 plays an important role

To elucidate the underlying mechanism of secretory leukocyte protease inhibitor (SLPI)-induced cell migration, we compared SLPI-deleted human gingival carcinoma Ca9-22 (Delta SLPI) cells and original (wild-type: wt) Ca9-22 cells using several microscopic imaging methods and gene expression analysis. Our results indicated reduced migration of Delta SLPI cells compared to wtCa9-22 cells. The lamellipodia/dorsal ruffles were smaller and moved slower in Delta SLPI cells compared to wtCa9-22 cells. Furthermore, well-developed intermediate filament bundles were observed at the desmosome junction of Delta SLPI cells. In addition,Galectin4was strongly expressed in Delta SLPI cells, and its forced expression suppressed migration of wtCa9-22 cells. Taken together, SLPI facilitates cell migration by regulating lamellipodia/ruffles and desmosomes, in which Galectin4 plays an important role