scholarly journals Ca2+-Dependent Cessation of Cytoplasmic Streaming Induced by Hypertonic Treatment in Vallisneria Mesophyll Cells: Possible Role of Cell Wall–Plasma Membrane Adhesion

2003 ◽  
Vol 44 (10) ◽  
pp. 1027-1036 ◽  
Author(s):  
Teruyuki Hayashi ◽  
Shingo Takagi
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cytoplasmic Streaming ◽  
Mesophyll Cells ◽  
Membrane Adhesion

Stationary organization of the actin cytoskeleton in Vallisneria: the role of stable microfilaments at the end walls

1995 ◽  
Vol 108 (4) ◽  
pp. 1531-1539
Author(s):  
J.H. Ryu ◽  
S. Takagi ◽  
R. Nagai
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Cytoplasmic Streaming ◽  
Cytochalasin B ◽  
Prior Treatment ◽  
Aquatic Angiosperm ◽  
Mesophyll Cells ◽  
Complicated Process ◽  
Side Walls

In mesophyll cells of the aquatic angiosperm Vallisneria gigantea, bundles of microfilaments (MFs) serve as tracks for the rotational streaming of the cytoplasm, which occurs along the two longer side walls and the two shorter end walls. The stationary organization of these bundles has been shown to depend on the association of the bundles with the plasma membrane at the end walls. To identify the sites of such association, the effects of cytochalasin B (CB) on the configuration of the bundles of MFs were examined. In the case of the side walls, MFs were completely disrupted after treatment with CB at 100 micrograms/ml for 24 hours. By contrast, in the case of the end walls, a number of partially disrupted MFs remained even after 48 hours of treatment. After removal of CB, a completely normal arrangement of bundles of MFs was once again evident within 24 hours after a rather complicated process of reassembly. When reassembly had been completed, the direction of cytoplasmic streaming was reversed only in a small fraction of the treated cells, suggesting that bundles of MFs are anchored and stabilized at the end walls of each cell and that the polarity of reorganized bundles and, therefore, the direction of the cytoplasmic streaming is determined in a manner that depends on the original polarity of MFs that remained in spite of the disruptive action of CB. By contrast, the direction of reinitiated cytoplasmic streaming was reversed in 50% of cells in which the bundles of MFs had been completely disrupted by exogenously applied trypsin prior treatment with CB.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Expression of a CO2-permeable aquaporin enhances mesophyll conductance in the C4 species Setaria viridis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Maria Ermakova ◽  
Hannah Osborn ◽  
Michael Groszmann ◽  
Soumi Bala ◽  
Andrew Bowerman ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Carbon Fixation ◽  
Foxtail Millet ◽  
Mesophyll Conductance ◽  
Mesophyll Cells ◽  
Green Foxtail ◽  
Targeted Expression ◽  
Fundamental Limitation ◽  
Leaf Biochemistry

A fundamental limitation of photosynthetic carbon fixation is the availability of CO2. In C4 plants, primary carboxylation occurs in mesophyll cytosol, and little is known about the role of CO2 diffusion in facilitating C4 photosynthesis. We have examined the expression, localization, and functional role of selected plasma membrane intrinsic aquaporins (PIPs) from Setaria italica (foxtail millet) and discovered that SiPIP2;7 is CO2-permeable. When ectopically expressed in mesophyll cells of S. viridis (green foxtail), SiPIP2;7 was localized to the plasma membrane and caused no marked changes in leaf biochemistry. Gas-exchange and C18O16O discrimination measurements revealed that targeted expression of SiPIP2;7 enhanced the conductance to CO2 diffusion from the intercellular airspace to the mesophyll cytosol. Our results demonstrate that mesophyll conductance limits C4 photosynthesis at low pCO2 and that SiPIP2;7 is a functional CO2 permeable aquaporin that can improve CO2 diffusion at the airspace/mesophyll interface and enhance C4 photosynthesis.

Structure and development of cortical microtubule arrays in plant cells

1978 ◽  
Vol 36 (2) ◽  
pp. 264-265
Author(s):  
A.R. Hardham ◽  
B.E.S. Gunning
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cortical Microtubule ◽  
Plant Cells ◽  
Original Description ◽  
Cell Cortex ◽  
Cortical Microtubules ◽  
Fundamental Part ◽  
Cellulose Component

Microtubules in the plant cell cortex are usually aligned parallel to microfibrils of cellulose that are being deposited in the cell wall, and are considered to function in guiding or orienting cellulose synthetase complexes that lie in or on the plasma membrane. The cellulose component is largely responsible for the mechanical reaction of the wall to turgor forces, thereby determining cell size and shape, and therefore the role of the cortical microtubules is a fundamental part of the overall morphogenetic process in plants. It is important to determine the structure of cortical arrays of microtubules and to learn how the cell regulates their development, neither of these aspects having been investigated adequately since the original description likened the microtubules to “hundreds of hoops around the cell”.

scholarly journals Plasma Membrane Localization Is Required for RasA-Mediated Polarized Morphogenesis and Virulence of Aspergillus fumigatus

2012 ◽  
Vol 11 (8) ◽  
pp. 966-977 ◽  
Author(s):  
Jarrod R. Fortwendel ◽  
Praveen R. Juvvadi ◽  
Luise E. Rogg ◽  
Yohannes G. Asfaw ◽  
Kimberlie A. Burns ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Aspergillus Fumigatus ◽  
Structural Changes ◽  
Hyphal Growth ◽  
Membrane Association ◽  
Ras Signaling ◽  
Ras Proteins ◽  
Content Type

ABSTRACT Ras is a highly conserved GTPase protein that is essential for proper polarized morphogenesis of filamentous fungi. Localization of Ras proteins to the plasma membrane and endomembranes through posttranslational addition of farnesyl and palmitoyl residues is an important mechanism through which cells provide specificity to Ras signal output. Although the Aspergillus fumigatus RasA protein is known to be a major regulator of growth and development, the membrane distribution of RasA during polarized morphogenesis and the role of properly localized Ras signaling in virulence of a pathogenic mold remain unknown. Here we demonstrate that Aspergillus fumigatus RasA localizes primarily to the plasma membrane of actively growing hyphae. We show that treatment with the palmitoylation inhibitor 2-bromopalmitate disrupts normal RasA plasma membrane association and decreases hyphal growth. Targeted mutations of the highly conserved RasA palmitoylation motif also mislocalized RasA from the plasma membrane and led to severe hyphal abnormalities, cell wall structural changes, and reduced virulence in murine invasive aspergillosis. Finally, we provide evidence that proper RasA localization is independent of the Ras palmitoyltransferase homolog, encoded by erfB , but requires the palmitoyltransferase complex subunit, encoded by erfD . Our results demonstrate that plasma membrane-associated RasA is critical for polarized morphogenesis, cell wall stability, and virulence in A. fumigatus .

scholarly journals Role of turgor pressure in endocytosis in fission yeast

2014 ◽  
Vol 25 (5) ◽  
pp. 679-687 ◽  
Author(s):  
Roshni Basu ◽  
Emilia Laura Munteanu ◽  
Fred Chang
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Fission Yeast ◽  
Turgor Pressure ◽  
Time Lapse ◽  
Actin Assembly ◽  
Latrunculin A ◽  
The Media ◽  
Time Lapse Imaging

Yeast and other walled cells possess high internal turgor pressure that allows them to grow and survive in the environment. This turgor pressure, however, may oppose the invagination of the plasma membrane needed for endocytosis. Here we study the effects of turgor pressure on endocytosis in the fission yeast Schizosaccharomyces pombe by time-lapse imaging of individual endocytic sites. Decreasing effective turgor pressure by addition of sorbitol to the media significantly accelerates early steps in the endocytic process before actin assembly and membrane ingression but does not affect the velocity or depth of ingression of the endocytic pit in wild-type cells. Sorbitol also rescues endocytic ingression defects of certain endocytic mutants and of cells treated with a low dose of the actin inhibitor latrunculin A. Endocytosis proceeds after removal of the cell wall, suggesting that the cell wall does not contribute mechanically to this process. These studies suggest that endocytosis is governed by a mechanical balance between local actin-dependent inward forces and opposing forces from high internal turgor pressure on the plasma membrane.

scholarly journals Role of Proton Motive Force in Photoinduction of Cytoplasmic Streaming in Vallisneria Mesophyll Cells

Plants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 376
Author(s):  
Akiko Harada ◽  
Yoshiji Okazaki ◽  
Toshinori Kinoshita ◽  
Reiko Nagai ◽  
Shingo Takagi
Keyword(s):  
Cytoplasmic Streaming ◽  
Red Light ◽  
Proton Motive Force ◽  
Motive Force ◽  
Activation Mechanism ◽  
Dependent Manner ◽  
Mesophyll Cells ◽  
P Type ◽  
Exchange Activity

In mesophyll cells of the aquatic monocot Vallisneria, red light induces rotational cytoplasmic streaming, which is regulated by the cytoplasmic concentration of Ca2+. Our previous investigations revealed that red light induces Ca2+ efflux across the plasma membrane (PM), and that both the red light-induced cytoplasmic streaming and the Ca2+ efflux are sensitive to vanadate, an inhibitor of P-type ATPases. In this study, pharmacological experiments suggested the involvement of PM H+-ATPase, one of the P-type ATPases, in the photoinduction of cytoplasmic streaming. We hypothesized that red light would activate PM H+-ATPase to generate a large H+ motive force (PMF) in a photosynthesis-dependent manner. We demonstrated that indeed, photosynthesis increased the PMF and induced phosphorylation of the penultimate residue, threonine, of PM H+-ATPase, which is a major activation mechanism of H+-ATPase. The results suggested that a large PMF generated by PM H+-ATPase energizes the Ca2+ efflux across the PM. As expected, we detected a putative Ca2+/H+ exchange activity in PM vesicles isolated from Vallisneria leaves.

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