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At least 37 records · Page 2Linked to original sources
PubMed1988

Bafilomycins: a class of inhibitors of membrane ATPases from microorganisms, animal cells, and plant cells.

Various membrane ATPases have been tested for their sensitivity to bafilomycin A1, a macrolide antibiotic. F1F0 ATPases from bacteria and mitochondria are not affected by this antibiotic. In contrast, E1E2 ATPases--e.g., the K+-dependent (Kdp) ATPase from Escherichia coli, the Na+,K+-ATPase from ox brain, and the Ca2+-ATPase from sarcoplasmic reticulum--are moderately sensitive to this inhibitor. Finally, membrane ATPases from Neurospora vacuoles, chromaffin granules, and plant vacuoles are extremely sensitive. From this we conclude that bafilomycin A1 is a valuable tool for distinguishing among the three different types of ATPases and represents the first relatively specific potent inhibitor of vacuolar ATPases.

Adenosine Triphosphatases↗
PubMed2006

Control of the actin cytoskeleton in plant cell growth.

Plant cells grow through increases in volume and cell wall surface area. The mature morphology of a plant cell is a product of the differential rates of expansion between neighboring zones of the cell wall during this process. Filamentous actin arrays are associated with plant cell growth, and the activity of actin-binding proteins is proving to be essential for proper cell morphogenesis. Actin-nucleating proteins participate in cell expansion and cell plate formation whereas the recycling of actin monomers is required to maintain actin dynamics and controlled growth. Coordination of actin-binding protein activity and other aspects of cytoskeletal behavior during cell development maintains cohesive cell expansion. Emerging plant signaling networks are proving to be powerful regulators of morphology-shaping cytoskeletal activity, and in this review we highlight current research in actin network regulation.

Actins↗
PubMed1998

On the relationship between the plant cell and the plant.

The mechanism by which higher plant cells divide is quite different from the animal system, and has implications for the way in which the processes of pattern formation, morphogenesis and cell differentiation are executed. The relationship between cell shape, cell division and differentiation and development will be considered from an evolutionary perspective, and the ways in which new molecular markers can inform our interpretation of these relationships will be considered.

Cell Differentiation↗
PubMed2005

Growth of the plant cell wall.

Plant cells encase themselves within a complex polysaccharide wall, which constitutes the raw material that is used to manufacture textiles, paper, lumber, films, thickeners and other products. The plant cell wall is also the primary source of cellulose, the most abundant and useful biopolymer on the Earth. The cell wall not only strengthens the plant body, but also has key roles in plant growth, cell differentiation, intercellular communication, water movement and defence. Recent discoveries have uncovered how plant cells synthesize wall polysaccharides, assemble them into a strong fibrous network and regulate wall expansion during cell growth.

Cell Wall↗
PubMed2001

Integrated bioprocessing for plant cell cultures.

Plant cell suspension culture has become the focus of much attention as a tool for the production of secondary metabolites including paclitaxel, a well-known anticancer agent. Recently, it has also been regarded as one of the host systems for the production of recombinant proteins. In order to produce phytochemicals using plant cell cultures, efficient processes must be developed with adequate bioreactor design. Most of the plant secondary metabolites are toxic to cells at the high concentrations required during culture. Therefore, if the product could be removed in situ during culture, productivity might be enhanced due to the alleviation of this toxicity. In situ removal or extractive bioconversion of such products can be performed by in situ extraction with various kinds of organic solvents. In situ adsorption using polymeric resins is another possibility. Using the fact that secondary metabolites are generally hydrophobic, various integrated bioprocessing techniques can be designed not only to lower toxicity, but also to enhance productivity. In this article, in situ extraction, in situ adsorption, utilization of cyclodextrins, and the application of aqueous two-phase systems in plant cell cultures are reviewed.

Acrylic Resins↗
PubMed2004

Determination of cell concentration in a plant cell suspension using a fluorescence microplate reader.

Microscopic counting of plant cells is a very tedious and time-consuming process and is therefore seldom used to evaluate plant cell number on a routine basis. This study describes a fast and simple method to evaluate cell concentration in a plant cell suspension using a fluorescence microplate reader. Eschscholtzia californica cells were fixed in a mix of methanol and acetic acid (3:1) and stained with a fluorescent DNA binding dye (Hoechst 33258). Readings were done in a fluorescence microplate reader at 360/465 nm. Specific binding of the dye to double-stranded DNA was significantly favored over unspecific binding when 1.0 M Tris buffer at pH 7.5 containing 1.0 M NaCl and 75 microg ml(-1) of Hoechst 33258 was used. Fluorescence readings must be done between 4 min and 12 min following the addition of the staining solution to the sample. The microplate counting method provides a convenient, rapid and sensitive procedure for determining the cell concentration in plant cell suspensions. The assay has a linear detection range from 0.2 x 10(6) cells to 10.0 x 10(6) cells per milliliter (actual concentration in the tested cell suspension). The time needed to perform the microplate counting was 10% of that needed for the microscopic enumeration. However, this microplate counting method can only be used on genetically stable cell lines and on asynchronous cell suspensions.

Bisbenzimidazole↗
PubMed1978

Mineral components of plant cell walls.

Plant cell walls that are secondarily thickened contain silicon and metal cations. The silicon occurs predominantly as silica (SiO2.nH2O) deposited in intimate association with the organic components of the walls and, according to recent evidence, as an integral constituent of polyuronides. Relatively large amounts of deposited (i.e., solid) silica are found in rice and other cereals and in grasses. When ingested by ruminant animals, practically all the solid silica may be recovered in the feces. However, microscopic particles of silica from plants are, to a small extent, absorbed as such through the gastrointestinal wall in both man and ruminant animals. It has now been shown that silicon is essential for animals, and that it is a constituent of certain mucopolysaccharides, thereby contribution to the architecture of connective tissues. The acidic silanol group of solid silica in plant cell walls may be involved in binding metal cations, but carboxyl and phenolic hydroxyl groups of the organic components of the walls are probably mainly responsible. Binding of metal cations by these components of plant cell walls, and possibly by silica, is likely to reduce availability of the cations for intestinal absorption.

Animal Nutritional Physiological Phenomena↗
PubMed2002

Dynamic changes and the role of the cytoskeleton during the cell cycle in higher plant cells.

In higher plant cells microtubules (MTs) show dynamic structural changes during cell cycle progression and play significant roles in cell morphogenesis. The cortical MT (CMT), preprophase band (PPB), and phragmoplast, all of which are plant-specific MT structures, can be observed during interphase, from the late G2 phase to prophase, and from anaphase to telophase, respectively. The CMT controls cell shape, either irreversibly or reversibly, by orientating cellulose microfibril (CMF) deposition in the cell wall; the PPB is involved in determining the site of division; and the phragmoplast forms the cell plate at cytokinesis. The appearance and disappearance of these MT structures during the cell cycle have been extensively studied by immunofluorescence microscopy using highly synchronized tobacco BY-2 cells. Indeed, these studies, together with visualization of MT dynamics in living plant cells using the green fluorescent protein, have revealed much about the modes of MT structural organization, for example, of CMTs at the M/G1 interphase. The microfilaments which also show dynamic changes during the cell cycle, being similar to MTs at particular stages and different at other stages, appear to play roles in supporting MTs. In this article, we summarize our ongoing research and that of related studies of the structure and function of the plant cytoskeleton during cell cycle progression.

Actin Cytoskeleton↗
PubMed2006

Microtubule cortical array organization and plant cell morphogenesis.

Plant cell cortical microtubule arrays attain a high degree of order without the benefit of an organizing center such as a centrosome. New assays for molecular behaviors in living cells and gene discovery are yielding insight into the mechanisms by which acentrosomal microtubule arrays are created and organized, and how microtubule organization functions to modify cell form by regulating cellulose deposition. Surprising and potentially important behaviors of cortical microtubules include nucleation from the walls of established microtubules, and treadmilling-driven motility leading to polymer interaction, reorientation, and microtubule bundling. These behaviors suggest activities that can act to increase or decrease the local level of order in the array. The SPIRAL1 (SPR1) and SPR2 microtubule-localized proteins and the radial swollen 6 (rsw-6) locus are examples of new molecules and genes that affect both microtubule array organization and cell growth pattern. Functional tagging of cellulose synthase has now allowed the dynamic relationship between cortical microtubules and the cell-wall-synthesizing machinery to be visualized, providing direct evidence that cortical microtubules can organize cellulose synthase complexes and guide their movement through the plasma membrane as they create the cell wall.

Cell Growth Processes↗
PubMed2006

Immunocytochemical localization of glutathione precursors in plant cells.

In plant cells, the antioxidant glutathione is synthesized out of its constituents cysteine, glutamate and glycine. As information about their subcellular and cellular distribution was not available in the past, the aim of the present study was to develop a technique that would allow visualization of their distribution in plant cells. With selective antibodies against cysteine, glutamate and glycine, it was possible, for the first time, to study the relative distribution of these components in meristematic root tip cells and mesophyll cells from older and younger leaves of Cucurbita pepo plants with the transmission electron microscope. These investigations revealed that high levels of cysteine accumulated in younger leaves. However, glutamate and glycine accumulated in the older ones, where cysteine levels were found to be significantly lower. On the subcellular level, glutamate was found in similar content in all investigated cellular compartments except for the cytosol, which showed up to 49% lower glutamate content (in younger leaves) than the other cell compartments. Levels of glycine were similar in all investigated cell compartments of one organ except vacuoles, which contained the lowest amounts of glycine. Cysteine was highest in plastids, the cytosol and in nuclei. When compared with younger leaves, glutamate and glycine were found to be accumulated in plastids (180 and 83%) and the cytosol (142 and 130%) of older leaves, whereas cysteine contents were found to be very low in the glutathione producing cell compartments of the leaves. These results indicate that low levels of cysteine might be a limitation for glutathione synthesis in older leaves. Cysteine and glycine were also detected in vacuoles where glutamate was absent. None of these components were detected in the apoplast. Therefore, these results indicate that glutathione degradation occurs within vacuoles or at the tonoplast, rather than at the plasmalemma or in the apoplast. Summing up, with the methods presented in this and a previous work, it is now possible to study the subcellular distribution of glutathione and its precursors in one plant sample simultaneously. The application of these methods on plant samples during abiotic and biotic stress situations should help us reveal possible limitations of glutathione synthesis during oxidative stress.

Cucurbita↗
PubMed1998

Genetics of plant cell shape.

Plant cells have a variety of shapes crucial for their functions, yet the mechanisms that generate these shapes are poorly understood. Genetic dissection of the trichome (plant hair) branching pathway in Arabidopsis, has uncovered mechanisms and identified genes that control plant cell morphogenesis. The recent identification of one of these genes, ZWICHEL (ZWI), as a novel member of the kinesin superfamily of microtubule motors provides a starting point for the analysis of the plant cytoskeleton's role in a specific morphogenetic event.

Arabidopsis↗
PubMed1982

A new method for the determination of hydraulic conductivity and cell volume of plant cells by pressure clamp.

Internodes of Chara corallina were used for experiments in which cell turgor pressure was clamped by means of the pressure probe technique. Essentially, the procedure consisted of a combination of volume and turgor pressure relaxations. This technique permits the determination of the cell volume by nonoptical means. The values obtained are in agreement with the ones determined by optical means. Furthermore, the hydraulic conductivity (L(p)) was determined from the initial slope of the volume relaxation; the values thus obtained are in agreement with those calculated from the half-times of pressure relaxations. The determination of L(p) from volume relaxation measurements has the advantage that the cell volume, the volumetric elastic modulus of the cell wall, and the internal osmotic pressure do not have to be known. Furthermore, the half-time of volume relaxation is longer than that of pressure relaxation, as shown by theory and experiment. This may be used to enhance the resolution of the relaxation measurement and, thus, to improve the accuracy of L(p) determinations for higher plant cells which exhibit a very fast pressure relaxation.

Journal Article↗
PubMed1998

Quantitative X-ray microanalysis of solutes in individual plant cells: a comparison of microdroplet and in situ frozen-hydrated data.

Two different approaches to X-ray microanalysis were tested and compared. These were the analysis of sap droplets extracted from individual cells (plants grown and analysed in Bangor, U.K.), and the analysis of cells in situ in frozen tissue (plants grown and analysed in Hannover, Germany). The data suggest that both these methods can produce quantitative data accurately reflecting in vivo concentrations in cereal leaf epidermal cells. The relative merits of the two procedures are discussed with reference to possible sources of error and their application to other cell types. Bulk wheat leaf tissue concentrations of K and Cl did not differ significantly between the two locations, but Ca concentration was significantly higher in the plants grown in Hannover. Microdroplet analysis invariably yielded linear responses in the range of concentrations found in plant tissue (r2 for Ca > 0.97, r2 for K, Cl > 0.99), and interference of other components of the sap was minimal. The calibration curves for the frozen-hydrated material were typically linear in the same range of concentrations (r2 for K, Ca, Cl > 0.95), and the results for K and Cl concentration in these samples were highly consistent with those measured in the microdroplet experiments. In wheat, for example, the cellular Cl concentration varied between 12 mM and 119 mM, but no significant differences were found between the two techniques of measurement. The results for cellular Ca differed in a manner which might be predicted from the results of the bulk tissue analyses.

Journal Article↗
PubMed2004

Comparative effects of various nitric oxide donors on ferritin regulation, programmed cell death, and cell redox state in plant cells.

Past studies investigating the regulatory functions of nitric oxide (NO) in plant cells have utilized various NO-donors that release NO in different redox forms, which has lead to problems in the interpretation of data. In the present study, the effects of different NO-donors releasing NO with either NO+ (SNP) or NO' (SNAP, GSNO, NOC-18) character have been compared in plant cells. In particular, ferritin regulation, programmed cell death, cellular redox state, and ROS-scavenging enzymes in Arabidopsis thaliana and Nicotiana tabacum cells were examined. The results show that SNP behaves differently than the other NO-donors tested; indeed, SNP induces accumulation of ferritin transcripts in Arabidopsis, whereas SNAP inhibits its accumulation. Moreover, among the assortment of donors tested, only SNP caused programmed cell death and suppression of ROS-scavenging systems.

Apoptosis↗
PubMed2004

Expression of functional human coagulation factor XIII A-domain in plant cell suspensions and whole plants.

Coagulation factor XIII, a zymogen present in blood as a tetramer (A2B2) of A- and B-domains, is one of the components of many "wound sealants" which are proposed for use or currently in use as effective hemostatic agents, sealants, and tissue adhesives in surgery. After activation by alpha-thrombin cleavage, coagulation factor XIII A-domain, a transglutaminase, is formed and catalyzes the covalent cross-linking of the alpha- and gamma-chains of linear fibrin to form homopolymers, which can quickly stop bleeding. We have successfully expressed the A-domain of factor XIII in both plant cell cultures and whole plants. Transgenic plant cell culture allows a rapid method for testing production feasibility while expression in whole plants demonstrates an economic production system for recombinant human plasma-based proteins. The expressed factor XIII A-domain had a similar size as that of human plasma-derived factor XIII. Crude plant extract containing recombinant factor XIII A-domain showed transglutaminase activity with monodansylcadaverine and casein as substrates and cross-linking activity in the presence of linear fibrin. The expression of factor XIII A-domain was not affected by plant leaf position.

Factor XIII↗