An anti-chlorpropham single-chain variable-fragment (scFv) gene was introduced into Arabidopsis in a manner to express the antibody fragment in each of four different subcellular compartments. The accumulation of scFv in transgenic plants was detected by targeting the fragment in the endoplasmic reticulum or apoplastic space, or by expressing the fragment as a glycosylphosphatidylinositol-anchored protein, while no accumulation could be detected by targeting the fragment in the cytosol. Transgenic plants accumulating the scFv gene at a high level in the endoplasmic reticulum had enhanced tolerance to chlorpropham in comparison with the non-transformants. (+info)
Isolation and characterization of mutants supersensitive to the spindle poison, isopropyl N-3-chlorophenyl carbamate (CIPC) in the fission yeast Schizosaccharomyces pombe.
(2/12)
Mutants supersensitive to the spindle poison, Isopropyl N-3-chlorophenyl carbamate (CIPC) of the fission yeast Schizosaccharomyces pombe were isolated and characterized genetically. Fourteen different recessive loci were assigned for the mutation (donated as cps1 to cps14) and two, cps1 and cps3, were mapped precisely on the chromosomes. Nine mutant strains were also supersensitive to phenothiazine derivatives, inhibitors of calcium-binding protein calmodulin. Four of nine strains were incapable of growing in the presence of 10 microM calcium ionophore A23187, at which the drug had no effect on cell growth in other strains. Fluorescence microscopy using the DAPI and Calcofluor staining methods showed two strains out of four to be defective in normal cell division; most stationary-phase cells of the cps6 mutant were seen to be bi- or tetra-nucleate, being partitioned with one or three septa, respectively. In the other mutant (cps8), enlarged cells were unequally partitioned with multisepta, and each compartment contained several daughter nuclei. The septa appeared aberrant in position within the cell, and situated diagonally but not vertically along the long cell axis. (+info)
Planktonic versus biofilm catabolic communities: importance of the biofilm for species selection and pesticide degradation.
(3/12)
The role of microfilaments and microtubules in apical growth and dimorphism of Candida albicans.
(4/12)
Cytoskeleton inhibitors were used to study morphogenesis in the pathogenic and dimorphic fungus Candida albicans. Nocodazole is a specific microtubule inhibitor and chloropropham (CIPC), at high concentrations, is an inhibitor of microtubules and microfilaments. Distribution of microtubules and microfilaments was studied by immunofluorescence techniques using anti-tubulin antibody with FITC-conjugated secondary antibody, and by staining with Rh-phalloidin. Nocodazole did not arrest apical cell elongation at a concentration (20 micrograms ml-1) that inhibited nuclear division and migration. Cytoplasmic and nuclear microtubules disappeared within 30 min in filamentous cells under these conditions. However, the Rh-phalloidin-stained actin granules which were localized in the tips of filamentous cells, and the microfilaments, were arranged normally at this concentration of nocodazole. Growth, and normal distribution of microtubules and microfilaments, were inhibited by a high concentration (200 micrograms ml-1) of CIPC. At a concentration (100 micrograms ml-1) of CIPC that permitted nuclear division, apical cell elongation was arrested, and filamentous growth was converted into yeast growth. At this concentration of CIPC, microtubules were distributed normally in filamentous cells. Long microfilaments were not observed, and actin granules did not localize in the tips of filamentous cells, but were distributed throughout the cytoplasmic cortex. Our results show that cytoplasmic microtubules are not essential for the elongation of filamentous cell tips but that microfilaments are apparently essential for this process. (+info)
The use of bio-guided fractionation to explore the use of leftover biomass in Dutch flower bulb production as allelochemicals against weeds.
(5/12)
Na+-coupled D-glucose uptake and membrane order of enterocyte brush border membrane vesicles, under the effect of a series of N-phenylcarbamates.
(6/12)
The importance of the hydrophobic effect of exogenous substances and of modifications of membrane order on D-glucose uptake are still poorly defined. Our results show that the concentrative Na+ -coupled D-glucose uptake of rat enterocyte brush border membrane vesicles is inhibited by N-phenylcarbamates increase the membrane order. However, since the concentrations required for membrane order increase are much greater than those active on D-glucose uptake, the effects on lipid order cannot be responsible for the inhibition of D-glucose uptake. Measurements of D-glucose uptake under conditions of Na+ equilibrium show that these carbamates do not act directly on the carrier but indirectly by favouring the dissipation of the Na+ gradient. (+info)
Immunofluorescence microscopy of microtubules in intact cell lineages of the moss, Physcomitrella patens. I. Normal and CIPC-treated tip cells.
(7/12)
Monoclonal antibodies to yeast tubulin have been used to visualize the distribution of microtubules in the intact filamentous protonemata of the moss Physcomitrella patens. Protonemata were prepared for immunofluorescence by fixation in formaldehyde and cells were made permeable with Driselase. Extensive cell files were preserved by 'blotting' the moss onto glutaraldehyde-derivatized coverslips. Problems due to fluorescence from chloroplasts were obviated by extraction with dimethyl sulphoxide and the non-ionic detergent, Nonidet NP40. These improvements allowed us to determine that microtubules were present throughout the cell cycle in the apical dome of caulonemal tip cells, that was a pronounced association of microtubules with the nucleus, that 'astral' microtubules were associated with the mitotic spindle and during anaphase may be involved in reorientation of the spindle before an oblique cytokinesis in caulonemata and that the cytokinetic phragmoplast appeared identical to the structure described for higher plants. Microtubules appeared to converge at the very tip of apical caulonemal cells and this was studied further by treating cells with CIPC--a drug that is known to produce multiple microtubule-organizing centres--and which here produces multiple foci for microtubules at the tip. These observations emphasize the involvement of microtubules in tip growth, alignment of the cell plate and nuclear migration--processes that are fundamental to the morphogenesis of filamentous organisms. (+info)
Microtubule biogenesis and cell shape in Ochromonas. 3. Effects of herbicidal mitotic inhibitor isopropyl N-phenylcarbamate on shape and flagellum regeneration.
(8/12)
The role of microtubules and microtubule nucleating sites in the unicell, Ochromonas has been examined through the use of two mitotic inhibitors, isopropyl N-phenylcarbamate (IPC) and isopropyl N-3-chlorophenyl carbamate (CIPC). Although IPC and CIPC have little or no effect on intact microtubules, the assembly of three separate sets of microtubules in Ochromonas has been found to be differentially affected by IPC and CIPC. The assembly of flagellar microtubules after mechanical deflagellation is partially inhibited; the reassembly of rhizoplast microtubules after pressure depolymerization is totally inhibited (however, macrotubules may form at the sites of microtubule initiation or elsewhere); and, the reassembly of the beak set of microtubules after pressure depolymerization may be unaffected although similar concentrations of IPC and CICP completely inhibit microtubule regeneration on the rhizoplast. These effects on microtubule assembly, either inhibitory or macrotubule inducing, are fully reversible. The kinetics of inhibition and reversal are found to be generally similar for both flagellar and cell shape regeneration. Incorporation data suggest that neither IPC nor CIPC has significant effects on protein synthesis in short term experiments. Conversely, inhibiting protein synthesis with cycloheximide has little effect on microtubule regeneration when IPC or CIPC is removed. Although the exact target for IPC and CIPC action remains uncertain, the available evidence suggests that the microtubule protein pool or the microtubule nucleating sites are specifically and reversibly affected. Comparative experiments using the mitotic inhibitor colchicine indicate some similarities and differences in its mode of action with respect to that of IPC and CIPC on assembly and disassembly of microtubules in these cells. (+info)