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At least 19 recordsLinked to original sources
PubMed1990

Production of a foreign protein product with genetically modified plant cells.

Plant cells (Nicotiana tabacum) were genetically engineered to produce a foreign protein, chloramphenicol acetyltransferase (CAT), and the CAT production from suspension cultures was investigated. Suspension cultures were grown in a shake flask, a stirred fermenter, and a bubble-column fermenter. The CAT production was growth related and the maximum activity was reached during the early stationary phase. A 41-day, semicontinuous stirred fermenter run, consisting of five sequential batch runs, demonstrated long-term CAT production. Continuous CAT production was also accomplished in a bubble-column fermenter at a medium flow rate of 3.1 ml h-1, which was equivalent to a dilution rate of 0.25 day-1.

Cells, Cultured↗
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↗
PubMed1991

Dielectric spectroscopy as a novel and convenient tool for the study of the shear sensitivity of plant cells in suspension culture.

Plant cell suspensions of different species and different age were subjected to hydrodynamic stress while following the decline in the volume fraction of intact cells by measuring the permittivity of the cell suspension at radio frequencies. Results were compared with the fresh weight, dry weight, packed cell volume and cell number of the suspensions. At first a rapid decline is seen as the most shear-sensitive cells are broken up, followed by a slower decline as less sensitive cells are broken up. The sensitivity of the cells to shear stress depended strongly on the cell line used but only slightly on their age, older cells being more sensitive. The dependence of the shear sensitivity on the cell line might be an effect of the species investigated, the culturing conditions of the cell line, or both. It was found that cells that grow in a finely dispersed suspension are much less prone to shear stress than is often assumed.

Cells, Cultured↗
PubMed1992

Bioconversion of naturally occurring precursors and related synthetic compounds using plant cell cultures.

The nearly unlimited enzymatic potential of cultured plant cells can basically be employed for bioconversion purposes. Plant enzymes are able to catalyze regio- and stereospecific reactions and can therefore be applied to the production of compounds of pharmaceutical interest. Naturally occurring as well as related synthetic compounds may be used as precursors. A review of the current status of such bioconversions is given. It includes the performance of bioconversions by freely suspended and immobilized plant cells or enzyme preparations. In addition, the kinetic aspects of immobilized plant cells are discussed. Special attention is paid to the bioconversion of poorly or water insoluble precursors. Finally, a model scheme for the development of a commercially available drug, produced by bioconversion, and perspectives are discussed.

Biotechnology↗
PubMed1979

Production of biologicals by plant cell cultures.

The biologicals currently produced from plants are generally low molecular weight chemicals such as drug compounds rather than high molecular weight compounds such as proteins. The reasons for considering a fermentation technology based on plant cell cultures have been described. The state of technology of plant cell cultures is sufficiently advanced to suggest that the major questions remaining are economic rather than primarily technical. Limited analysis of the economics of commercial production of biologicals by plant cell cultures shows that a commercial process is certainly feasible.

Biological Products↗
PubMed1992

Problems of optimisation of plant cell culture processes.

The adoption of plant cell cultures as an industrial process depends greatly on the economics of such a process. The multicycle or draw-fill culture technique is one method for improving the productivity and, hence, cost of a process. Mathematical models have been devised for the functional relationships between the nominal costs of biomass and secondary metabolites and the plant cell growth characteristics in a multicycle growth system. The models were used to evaluate the data obtained with cultures of Dioscorea deltoidea (which produces diosgenin) and Panax ginseng, grown in various types of bioreactors. The multicycle system gave an increase of 1.5-2 in biomass productivity compared with batch culture, but was probably only commercially viable if the cost of the process in the bioreactor was at least 30 times that of the medium and if an inoculum of about 30% of the culture of the previous cycle was left in the bioreactor. In the multicycle system incompletely utilised nutrient or metabolite accumulation can only reach 1.43 times or less that of the initial values. With the P. ginseng culture, about 75% of the calculated maximum cell packing density per fresh weight (approximately 530 g 1-1) in this regime was achieved. The possibility of growth in the standard bioreactor of a shear sensitive type culture was shown with a marine impeller speed up to 330 cm s-1.

Biotechnology↗
PubMed1992

Synthesis, assembly and function of plant cell wall macromolecules.

The plant cell wall consists of a structurally intricate network of polysaccharide and protein whose biosynthesis, assembly and functions are still poorly understood. Recent research has shown how cell wall macromolecules, and fragments thereof, appear to be involved in processes such as cell growth, cell and tissue differentiation and the control of pathogenesis.

Cell Wall↗
PubMed1978

Inducing effect of plant cells on nitrogenase activity by Spirillum and Rhizobium in vitro.

Eleven different plant cell tissue cultures of both legume and non-legume origin have been grown in direct association, and in separate but close proximal association with both Spirillum lipoferum and Rhizobium sp. 32H1. Basic similarities were found in the nutritional requirement for the induction of nitrogenase activity (C2H2) in both organisms. In the absence of plant cell cultures both organisms need to be provided with a pentose sugar and a tricarboxylic acid to induce high levels of nitrogen-fixing activity. Plant cell callus tissue appears only capable of supplying the tricarboxylic acid to induce high levels of nitrogen-fixing activity. Plant cell callus tissue appears only capable of supplying the tricarboxylic acids needed but not the sugar component. The plant tissue, however, seems able to activate certain carbohydrates, which in themselves are incapable of substituting for the pentose additive.

Enzyme Induction↗
PubMedDate not supplied

Transfer, maintenance, and expression of bacterial Ti-plasmid DNA in plant cells transformed with A. tumefaciens.

The mechanism of induction of the plant cancer crown gall by Agrobacterium tumefaciens has been briefly described. The salient points are as follows. 1. Large plasmids of molecular weight (100 to 150) S 10(6), called Ti-plasmids, are essential to the transformation process. 2. Ti-plasmids carry a DNA segment that can be transferred to, and maintained and expressed in, transformed plant cells. 3. This DNA segment has been identified both by direct hybridization experiments between Ti DNA fragments and crown gall DNA and by the study of a deletion mutant of a Ti-plasmid. 4. Indirect evidence suggests that genes involved in the synthesis of abnormal amino acids (such as octopine and nopaline) by crown gall cells, and known to be carried on the Ti-plasmids, are in fact located on the DNA segment that is transferred to the plant cells. 5. Ti-plasmids are efficient conjugative plasmids, since they can promote their own transfer by conjugation to various plasmid-free bacterial strains. Their conjugative properties may be involved also in the Ti DNA transfer from Agrobacterium to plant cells. 6. Preliminary evidence indicates that the transferable segment of the Ti-plasmid has the structure of a transposon, since it appears to be flanked by a sequence exhibiting most of the properties of the sequences that border the known bacterial drug-resistance gene transposons.

Cell Transformation, Neoplastic↗
PubMed1992

Secondary fungal metabolites and their biological activities, II. Occurrence of antibiotic compounds in cultures of Armillaria ostoyae growing in the presence of an antagonistic fungus or host plant cells.

We found that in the presence of host plant cells or some antagonistic fungi, the highly forest-pathogenic basidiomycete Armillaria ostoyae is strongly stimulated to produce a series of toxic secondary metabolites which are capable of inhibiting the growth of the antagonist or of killing the plant cells still before cell contact. The chemical structures of the metabolites have been identified, of which two of them are new compounds. The time dependence and sites of synthesis in the mycelium have been determined in order to lay the foundation for future studies concerning the induction mechanism for the synthesis of the toxins.

Anti-Bacterial Agents↗
PubMed1976

Differential staining of tannin in sections of epoxy-embedded plant cells.

A staining procedure is described for the light microscopic localization of ergastic tannins in epoxy sections of plant cells embedded for study by transmission electron microscopy. Callus and cell suspensions of Pseudotsuga menziesii and Pinus taeda fixed in glutaraldehyde:acrolein and then OsO4, followed by epoxy embedding, were sectioned 0.5 mum thick, stained on a glass slide with ethanolic Sudan black B at 60 C as described by Bronner, and then mounted in Karo syrup. Tannin deposits stained brownish-orange and were easily distinguished from lipid bodies of similar size, which stained dark blue to black, and from starch grains, which were unstained. The significance of this differential polychromasia was confirmed by transmission electron microscopy. This staining procedure should prove valuable in the cytoplasmic evaluation of the plant cell ergastics (especially tannins) via light microscopy whether or not electroc microscopic examination is intended.

Plant Cells↗
PubMed1991

Large-scale plant cell culture: methods, applications and products.

Recent significant contributions to the design of large-scale plant cell cultures for secondary metabolite production include: the development of a strategy to control the concentration of dissolved gases at constant shear; a surface immobilization technique to retain cell mass at high mixing rates; and a modified stirred-tank reactor with a mesh cage to prevent damage of hairy root cultures.

Biotechnology↗
PubMed1978

Ribonuclease H activity in cultured plant cells.

Ribonuclease H (RNAase H) was extracted from cultured plant cells, strain GD-2 and characterized. RNAase H activity in logarithmical growing cells is much higher than that of stationary cells, and the response of RNAase H activity was very similar to that of DNA polymerase after culture. The activities of RNAase, DNAase, phosphodiesterase and alkaline phosphatase decrease parallel with the increase in growth, and increase to stationary phase, contrasting with those of DNA polymerase and RNAase H.

Cell Division↗
PubMed1992

Cytoplasmic chloride regulates cation channels in the vacuolar membrane of plant cells.

This study is concerned with the characterization of the ionic currents in the vacuolar membrane (tonoplast) of plant cells. Voltage patch-clamp experiments at the whole vacuole and single channel levels were employed to study the effects of cytoplasmic chloride on the tonoplast inward rectifying currents of sugar beet cultured cells. Whole vacuole experiments showed that removal of cytoplasmic chloride induced a decrease in the level of the inward currents, an effect that was reversed upon returning to control levels of cytoplasmic chloride. Substitution of cytoplasmic chloride by any other anion (organic or inorganic) resulted in a reduction in the level of the inward currents. At a given negative tonoplast potential, the inward currents showed a linear relationship with the concentration of cytoplasmic chloride between 10 and 100 mM, with the slope of these relationships increasing as the potential was made more negative. Single channel experiments showed that reduction of cytoplasmic chloride changed the gating mechanism of the channels without affecting the single channel conductance. Reduction of cytoplasmic chloride caused a decrease in the open probability of the tonoplast cation channels by reducing their mean open time and by inducing the appearance of an additional closed state.

Cells, Cultured↗
PubMed1978

The lignin fraction of plant cell walls.

Methods are discussed for determining lignin in plant cell walls. The increase in apparent lignin content that may occur as a result of artifacts produced during food preparation is also discussed. The phenolic components, including lignin, of cell walls separated from 12 vegetable, fruit, and cereal foods are determined. Wheat bran, on a fresh weight basis, had a high cell wall content (48.6%) compared with the vegetables and fruit whose contents ranged from 1.0 to 6.0%. Wheat bran and spinach cell walls had the highest lignin contents (11.4 and 4.4%, respectively) and the lowest degradabilities (35.8 and 39.6%, respectively) as determined by a cellulase technique. Cell walls of spinach, beetroot, sweet corn, pineapple, and wheat bran contained the phenolic acids (ferulic, p-coumaric, and diferulic) bound to polysaccharide components. Cell walls of cabbage, Brussels sprout, celery, cauliflower, green bean, carrot, and pea contained only traces of these acids.

Cell Wall↗