Wall Chemical Composition Research Articles

Cell wall composition and structure of Yarrowia lipolytica transposon mutants affected in calcofluor sensitivity.

A collection of transposon-mutagenized strains of Yarrowia lipolytica was screened for wall defects by determination of their sensitivity to calcofluor white. A number of strains were hypersensitive, whereas others were resistant. Different non-allelic mutants displayed increased sensitivity to autolysis and lytic enzymes, independently of whether they were sensitive or resistant to calcofluor white. A thorough analysis of their cell walls revealed minor quantitative alterations, and no significant changes in chitin content. Electrophoretic analysis of wall-bound and excreted proteins proved to be a sensitive method that revealed defects in the cell wall structure of the mutants. Important alterations in the patterns of the wall proteins extracted by SDS or by enzymatic treatments were noticed for the mutants, as compared to the parental strain. Mutants released to the growth medium a larger number of protein species than the parental strain, suggesting impairment in wall assembly of certain polypeptides. Patterns of wall-bound and excreted proteins, as well as alterations in wall chemical composition were not diagnostic of calcofluor white sensitivity or resistance, but were specific for each mutant. Our data show that an increase in either sensitivity or resistance of Y. lipolytica to certain levels of calcofluor is equally indicative of alterations in cell wall structure, independent of chitin levels.

182 Chemical Changes in the Cell Wall Composition of Calcium-infiltrated `Golden Delicious' Apples

`Golden Delicious' apples (Malus ×domestica Borkh.) were pressure-infiltrated after harvest with 0%, 1%, 2%, 3%, or 4% CaCl2 solutions (w/v) and the chemical composition of the cell wall of the cortical tissue 2 to 4 mm under the epidermis was studied. The mineral composition of the control cell wall (0% CaCl2) was not affected by the pressure infiltration process. In addition, no significant change was noticed in cell wall associated protein, uronic acid, total polysaccharides, or non-cellulosic neutral sugar contents except for xylose and rhamnose, which decreased (-25%) and increased (+20%), respectively. When apples were infiltrated with CaCl2, Ca content of the cell wall increased and maximum accumulation was achieved with a 2% CaCl2 solution. Calcium infiltration also induced a two-fold increase in Na, a 27% decrease in P, and a 40% decrease in protein content. These data suggest that chemical changes occurring after Ca infiltration are not related to pressure infiltration alone, but are mainly due to the Ca accumulation in the cell wall after pressure infiltration of CaCl2 solutions. Saturation of the available binding sites for Ca occurred in the cell wall when fruit were infiltrated with 2% CaCl2, as no further significant changes in the cell wall chemical composition was detected in fruits infiltrated with 3% or 4% CaCl2.

Permeability assessment of capsules for islet transplantation.

Despite considerable progress in the development of immunoisolation devices, the optimal permeability of such devices is not known. This limitation stems partly from deficits in knowledge about which molecules should be allowed to traverse the semipermeable membrane and which molecules should be excluded, and also partly from experimental obstacles that have prevented a systematic study of permeability. To determine the optimal permeability of immunoisolation devices, we have created a series of microcapsules (800 microM diameter) that span a broad range of molecular exclusion limits yet are identical in wall thickness and chemical composition. Capsule permeability was precisely defined by two complementary methods--size exclusion chromatography (SEC) and a newly developed methodology to assess permeability of biologically relevant proteins. The entry of interleukin-1 beta-125I was significantly delayed, but not prevented, when the capsule exclusion limit was decreased from 230 kD to 3.2 kD, as determined by SEC with dextran standards. The influx of IgG was as predicted, based on the viscosity radius R eta of IgG and the capsule exclusion limit defined by SEC. Glucose-stimulated insulin secretion by encapsulated pancreatic islets did not differ as capsule permeability was decreased from a molecular exclusion limit of 230 kD to 120 kD. These studies should assist in the design of immunoisolation devices by defining the permeability optimal for cell function and also should be applicable to any cell type or immunoisolation device.

Cell surface characteristics of Lactobacillus casei subsp. casei, Lactobacillus paracasei subsp. paracasei, and Lactobacillus rhamnosus strains.

Hydrophilic and electrostatic cell surface properties of eight Lactobacillus strains were characterized by using the microbial adhesion to solvents method and microelectrophoresis, respectively. All strains appeared relatively hydrophilic. The strong microbial adhesion to chloroform, an acidic solvent, in comparison with microbial adhesion to hexadecane, an apolar n-alkane, demonstrated the particularity of lactobacilli to have an important electron donor and basic character and consequently their potential ability to generate Lewis acid-base interactions with a support. Regardless of their electrophoretic mobility (EM), strains were in general slightly negatively charged at alkaline pH. A pH-dependent behavior concerning cell surface charges was observed. The EM decreased progressively with more acidic pHs for the L. casei subsp. casei and L. paracasei subsp. paracasei strains until the isoelectric point (IEP), i.e., the pH value for which the EM is zero. On the other hand, the EM for the L. rhamnosus strains was stable from pH 8 to pH 3 to 4, at which point there was a shift near the IEP. Both L. casei subsp. casei and L. paracasei subsp. paracasei strains were characterized by an IEP of around 4, whereas L. rhamnosus strains possessed a markedly lower IEP of 2. The present study showed that the cell surface physicochemical properties of lactobacilli seem to be, at least in part and under certain experimental conditions, particular to the bacterial species. Such differences detected between species are likely to be accompanied by some particular changes in cell wall chemical composition.

Kinetics of primary biodegradation of sulphosuccinate esters by Comamonas terrigena

A series of in vitro experiments were completed to evaluate the potential of enzyme extracts, obtained from the white-rot fungi Trametes versicolor (TV1, TV2), Bjerkandera adusta (BA) and Fomes fomentarius (FF), to increase degradation of cell wall components of wheat straw. The studies were conducted as a completely randomized design and analysed using one-way ANOVA. Enzyme activities of the extracts, previously obtained from a liquid culture medium, were characterized in terms of laccase and peroxidase for ligninolytic activity. Carboxymethyl cellulase (CMCase) and avicell digesting cellulase (Avicelase) were used for cellulolytic enzyme assays. Wheat straw samples were incubated with enzyme extracts in a citrate buffer (pH 5.0) in a forced air oven at 25 °C for 6 days. In vitro NDF digestibility (IVNDFD), and the rate and extent of NDF fermentation, without and after incubation with the white-rot enzyme extracts, were determined using a gravimetric microbiological method and a gas production technique, respectively. Results from cell wall chemical composition showed that TV2 and BA enzyme extracts decreased NDF concentration (P<0.05) and that TV1 had higher activity (P<0.05) towards cellulose. There was an increase in IVNDFD (P<0.05), resulting from treatment of wheat straw with enzyme extracts from BA, TV1 and TV2, reaching a difference of 13% for TV2 (P<0.05), versus the non-treated straw control. Treatment with enzyme extract from TV2 caused increased gas production (P<0.05) after the first 20 h of incubation, and also increased the maximum rate of gas production, thus enhancing fermentation kinetics. This study indicates that enzyme extracts from white-rot fungi can be used to develop new approaches to overcome low digestibility of some plant cell walls. Utilization of different substrates to produce enzyme extracts can lead to production of viable ligninolytic complexes which could improve the nutritive value of fibrous feeds.

Some significant differences in wall chemistry among four commercial Agaricus bisporus strains

Significant differences in gross wall chemical composition were detected in four commercial Agaricus bisporus strains. All were grown under the same conditions and their walls prepared by a mild method of breakage. A more detailed analysis of the wall fractions, isolated by means of their distinct solubilities, also showed striking structural differences among the four strains studied. The detected differences, not only in the overall composition of the wall but also in the polysaccharide structure, could assist in the characterization of strains and/or varieties of the commercial basidiomycete A. bisporus.

Characterization of a Rhodococcus species that utilizes numerous aromatics

Rhodococcus species were isolated from oil-soaked soil in Newfoundland and found to utilize numerous aromatic compounds as sources of carbon and energy. This Gram-positive bacterium exhibited rod-cocci dimorphism during its growth cycle. Cell wall chemical composition (amino acids, sugars and fatty acids) was determined using gas chromatography-mass spectrometry and high pressure liquid chromatography. Comparison of both acid production and growth substrates showed complete homology with Rhodococcus erythropolis No. 4277. A numerical taxonomic approach clustered the isolates with the genus Rhodococcus. Tentatively we have identified the aromatic-degrading isolates as Rhodococcus species.

Changes of Cell Wall Composition and Polymer Size in Primary Roots of Cotton Seedlings Under High Salinity

The aim of this study was to investigate changes in cell wall chemical composition and polymer size in the root tip of intact cotton seedlings (Gossypium hirsutum L. cv. Acala SJ-2) grown in saline environments, in order to relate the interaction between high salinity and root growth to possible changes in cell wall metabolism. Cotton seedlings were grown in modified Hoagland nutrient solution with various combinations of NaCl and CaCl 2 . Cell walls were fractionated into four fractions (pectin, hemicellulose 1 and 2, cellulose), and analysed for their total sugar content, neutral sugar composition and size of polysaccharides. At 1 mol m −3 Ca, 150 mol m −3 NaCl resulted in a significant increase in the cell wall uronic acid content, but a reduction in cellulose content on a per unit dry weight basis

Wood and cellulosic chemistry

Ultrastructure and formation of wood cell wall chemical composition and distribution structure of cellulose - recent developments in its characterization chemistry of lignin chemistry of cell wall polysaccharides chemistry of extractives chemistry of bark chemical characterization of wood and its components colour and discoloration chemical degradation weathering and photochemistry of wood microbial, enzymatic and biomimetric degradation of lignin in relation to bioremediation chemical modification of wood chemical modification of cellulose chemical synthesis of cellulose wood plasticization wood-polymer composites adhesion and adhesives pressure-sensitive adhesives and forest products wood-inorganic composites as prepared by the sol-gel process preservation of wood conservation of waterlogged wood biodegradable plastics from lignocellulosics recycling of wood and fibre products pulping chemistry.

Mechanical Structure of the Stem of Arborescent Palms

Mechanical properties of the stem tissue were examined for the arborescent rain forest palms Welfia georgii, Iriartea gigantea, Socratea durissima, Euterpe macrospadix, Prestoea decurrens, and Cryosophila albida. Dry density, elastic modulus, and modulus of rupture are greatest toward the base and periphery of palm stems. All of these properties increase markedly with inferred age. The capacity to increase stem stiffness and strength is the major means by which arborescent palms compensate for increased structural demands during height growth. Young palms are overbuilt with respect to diameter and older palms are underbuilt, compared with arborescent dicotyledons and conifers. Yet there is a tendency to maintain a constant margin of safety against mechanical failure by increases in stem tissue stiffness and strength, with initial low values increasing to exceptionally high values. Stiffness and strength of palm stem tissue increase more rapidly with specific gravity than would be expected from existing models that describe mechanical properties of cellular solids. This difference between palm stem tissue and common woods may result from differences in cell structure and cell wall chemical composition.

Leptotrichia buccalis a Gram-negative bacterium

Oral strains of Leptotrichia buccalis (Robin) Trevisan 1879, 138 (Basionym Leptothrix buccalis Robin 1853, 394) were found to be Gram-negative, on the basis of cell wall morphology and chemical composition. The G-C ratio 34 mole per cent places L. buccalis in a group with the genera Sphaerophorus and Fusobacterium in the family Bacteroidaceae.

LIGNIFICATION AND IN VITRO CELL WALL DIGESTIBILITY OF PLANT PARTS

The in vitro cell wall digestibility and chemical composition were determined with a total of 56 forage samples. Two samples each of Dactylis glomerata L., Bromus inermis Leyss., Medicago sativa L., and Lotus corniculatus L. were collected at three maturities. Two samples of Symphtum officinale L. were collected at two maturities. All samples were later separated into leaf and stem portions. Wide variation existed in chemical composition and digestibility. The range in cell wall constituents was 23.9 to 79.8%, in acid detergent fiber 16.9 to 52.3%, and in lignin 3.7 to 19.1%. The in vitro cell wall digestibility varied from 16.6 to 77.5%. Correlation coefficients between lignin content and cell wall digestibility were higher when lignin was expressed as a percentage of dry matter rather than as a percentage of cell walls. In grasses, the relationship between lignin in cell walls and cell wall digestibility was linear. However, cell wall digestibility of legumes and Russian comfrey was not as low as expected from the content of lignin.