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PubMed1985

Characterization of Chlamydomonas sexual agglutinins.

Molecules (agglutinins) mediating mating-type-specific adhesion of Chlamydomonas reinhardtii plus and minus gametes have been purified and shown to be homologous by several criteria. Both are large, extrinsic glycoproteins, rich in hydroxyproline and serine, which to a variety of inactivating agents. Direct visualization of agglutinins by the rapid-freeze deep-etch technique of Heuser reveals that both are extremely asymmetric, fibrous molecules with similar but distinct topographies. Each has a globular head, a rigid domain, a relatively flexible region and a terminal hook. In situ images show that the molecules associate with the flagellar surface via the latter (hook) domain, projecting the globular head distally. A functional role for the head is implied from inactivation studies (thermolysin digestion and reduction/alkylation) showing a selective modification of this domain. A library of monoclonal antibodies, raised against the plus agglutinin, has been used to probe the structural organization of this molecule by immunotopographic mapping. Two Two distinct classes of monoclonal antibodies are shown to react with carbohydrate epitopes localized to the two termini (head and hook) of the plus agglutinin while a third recognizes a polypeptide determinant that repeats along the rod-like portion of the molecule. The latter class is gamete (but not mating-type)-specific while the other two classes display distinct patterns of cross reactivity. Finally, the Chlamydomonas agglutinins show a striking compositional and structural resemblance to the major cell wall glycoproteins of this organism. Wall glycoproteins, which are also rich in hydroxyproline and serine and capable of self-assembly, may therefore share a common evolutionary heritage with the agglutinins.

Amino Acids↗
PubMed1989

Two new carbapenem antibiotic-producing actinomycetes: Kitasatosporia papulosa sp. nov. and Kitasatosporia grisea sp. nov.

Two new carbapenem antibiotic-producing actinomycetes, the cell-walls of which contain LL-diaminopimelic acid and meso-diaminopimelic acid, were isolated from soil. The two strains were subjected to taxonomic studies, which involved morphological, cultural, physiological and chemotaxonomical characterization, the latter including the cell-wall chemo-type, whole-cell sugar composition, phospholipid composition, menaquinone system and DNA base composition. These strains were identified as new species of the genus Kitasatosporia. The proposed names are Kitasatosporia papulosa for strain AB-110 (IAM 13637, FERM 9000, JCM 7250) and Kitasatosporia grisea for strain AA-107 (IAM 13638, JCM 7249).

Actinomycetales↗
PubMedDate not supplied

[The biology and osmoadaptation of haloalkaliphilic methanotrophs].

There is increasing evidence for the presence and activity of methanotrophic bacteria in saline and alkaline aquatic environments located in different ecogeographical regions. Alkalitolerant halophilic and alkaliphilic halotolerant methanotrophs of type I were found to be able to utilize methane and methanol, to oxidize ammonium ions, and to transform various organic compounds in a wide range of water salinities (up to 12% NaCl) and pH values (from 5 to 11). The ecophysiological importance of methanotrophs in microbial communities inhabiting saline and alkaline aquatic environments is due to their involvement in the global cycles of methane and major bioelements (C, N, and S). Specific cyto- and biochemical properties of haloalkaliphilic methanotrophs--the synthesis of osmoprotectants (ectoine, 5-hydroxyproline, and sucrose), the accumulation of potassium ions, the formation of glycoprotein S layers on the outer surface of their cell walls, and the modification of the chemical composition of their membranes--allow them to adapt to highly saline and alkaline habitats. Due to their specific properties, haloalkaliphilic methanotrophs may become of use in modern biotechnology.

Adaptation, Physiological↗
PubMed1995

Effect of hydrothermal treatment of rice straw on its composition and in sacco digestibility and in vitro fermentation by rumen microorganisms.

Chemical composition, in sacco rumen disappearance of various cell wall constituents (CWC) and in vitro fermentation pattern of hydrothermally treated (1 to 14 kp/cm2 pressure for 5 min) rice straw was examined. At 10 kp/cm2 pressure treatment (maximum effect) the contents of dry matter (DM), organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF), hemicellulose (HC) and cellulose (CE) were decreased by 32.5, 35.3, 27.8, 10.2, 61.2 and 25.1%, respectively (P < 0.05), over the untreated control. The in sacco rumen disappearance of DM, OM, HC and CE from rice straw treated at 8 kp/cm2 pressure (maximum effect) and incubated for 48 h was increased from 53.2 to 77.7, 52.4 to 80.3, 49.5 to 82.0 and 49.2 to 79.3%, respectively (P < 0.01). In vitro production of total volatile fatty acids and the content of TCA-insoluble protein was also significantly higher (P < 0.05) on treated compared with untreated straw.

Animal Feed↗
PubMed1992

Short-chain fatty acid production and fiber degradation by human colonic bacteria: effects of substrate and cell wall fractionation procedures.

Three dietary fiber sources (corn fiber, oat bran, wheat bran) were analyzed for chemical composition and potential fermentation by human colonic bacteria in vitro. Total dietary fiber (TDF) concentration of substrates was 64.3, 11.1 and 50.4 g/100 g dry matter for corn fiber, oat bran and wheat bran, respectively. Original material (ORIG), TDF fractions and simulated (SIM) cell wall fractions (produced by combining cellulose, hemicelluloses and pectic substances in proportions they represented in the cell wall) from each substrate were fermented in vitro for 6, 12, 18, 24 or 48 h using inoculum prepared from freshly voided feces from each of three human volunteers. Substrate dry matter remaining after 48 h of fermentation was 87.8, 39.8 and 73.5% for TDF fractions of corn fiber, oat bran and wheat bran, respectively. Disappearance of ORIG fractions was considerably greater than that of TDF due to fermentation of nonfibrous material. Disruption of cell wall structure during isolation of polysaccharide fractions allowed for dramatically increased fermentability of SIM relative to TDF. Averaged across all treatments, production of the short-chain fatty acids, acetate, propionate and butyrate, occurred in the molar ratio 63:21:16; however, profiles of short-chain fatty acids produced were influenced by both treatment and inoculum source. Extent of substrate fermentation varied among inoculum donors, implying that colonic microbial activities differ among individuals. Potential colonic fermentability of fiber sources was influenced by substrate, method of fiber preparation and inoculum source.

Adult↗
PubMed1980

Isolation and characterization of outer and inner membranes of Selenomonas ruminantium: lipid compositions.

The isolation procedure and characterization of the outer and inner membranes from Selenomonas ruminatium cells, a strictly anaerobic bacterium, are described. The metabolic fate of [14C]decanoate incorporated into the outer and inner membranes was examined. The percent distribution of radioactivities in the outer and inner membranes was about 40 and 50% of the total incorporated activity, respectively. Approximately 47% of the radioactivity incorporated into the outer membrane was recovered in the phospholipid fraction, and the remaining radioactivity was found in both aqueous and phenol layers when the outer membrane was treated with phenol-water. In contrast to [14C]decanoate, the percent distribution of [3H]glycerol in the outer and inner membranes was about 25 and 70% of the total incorporated activity, respectively. Most of the assimilated 3H was located in the phospholipid fraction of both membranes. However, no significant label was detected in either the protein or cell wall fraction. The following observations were made concerning lipid compositions in the outer and inner membranes by chemical and isotopic analyses. (i) The outer and inner membranes contained no detectable phosphatidyl glycerol or cardiolipin. (ii) A prominent radioactive compound, designated band III lipid, was found mainly in the outer membrane as a major radioactive spot when cells were grown with [14C]decanoate. This lipid contained phosphorus, 2-keto-3-deoxyoctulosonic acid and 3-OH fatty acid but no detectable glycerol. This lipid was identified tentatively to be 2-keto-3-deoxyoctulosonic acid-lipid A. (iii) Although the ubiquity of phosphatidyl ethanolamine plasmalogen in both outer and inner membranes was confirmed, the occurrence of the molecular species of phosphatidyl ethanolamine plasmalogen was quite different in the outer and inner membranes.

Aldehydes↗
PubMed2000

Accumulation of lymphocytes, dendritic cells, and granulocytes in the aortic wall affected by Takayasu's disease.

The aim of this study was to analyze the cellular composition of the arterial wall in Takayasu's disease and to investigate the contribution of the various cell types to the immunoinflammatory processes and degenerative alterations of the vessel wall in this disease. Specimens of aorta were obtained at operation from 10 patients with Takayasu's arteritis. The duration of disease ranged from 2 months to 13 years. Immunohistochemical investigation was carried out using the antibodies CD3 (to identify T-cells), CD20 (B-cells), S-100 (dendritic cells), CD68 (macrophages), CD15 (granulocytes), von Willebrand factor (endothelial cells), and alpha-smooth muscle actin (smooth muscle cells). All specimens showed distinctive histologic features of Takayasu's arteritis and contained inflammatory infiltrates, but the degree of their accumulation within the aortic wall varied. Inflammatory infiltrates within the deep part of the intima, around areas of neovascularization and within the adventitia contained T-cells colocalizing with dendritic cells. Nodules formed by large numbers of intermingling T-cells and B-cells enriched with dendritic cells were observed in the adventitia. Massive accumulation of granulocytes and their destruction within the adventitia were prominent in all cases. This is the first study that establishes the presence of dendritic cells and granulocytes in Takayasu's disease. Dendritic cells are probably involved in the immunoinflammatory processes through their interaction with T-cells and B-cells. The present observations may help understanding of the pathogenesis of Takayasu's disease.

Adult↗
PubMed1974

Subunit cell wall of Sulfolobus acidocaldarius.

The cell wall of Sulfolobus acidocaldarius has been isolated. Cells were mechanically disrupted with a French press, and the cytoplasmic membrane was removed by extracting cell-envelope fragments with Triton X-100. The Triton-insoluble cell wall material retained the characteristic subunit structure when examined in the electron microscope. Isolated cell wall fragments formed in open sheets that were easily separated from cytoplasmic contamination. Chemical studies showed that the Triton-insoluble cell wall fragments consisted of lipoprotein with small amounts of carbohydrate and hexosamine. The amino acid composition indicated a highly charged hydrophobic cell surface. The presence of diaminopimelic acid with only traces of muramic acid indicates that the cell envelope does not have a rigid peptidoglycan layer. The results of chemical analyses and electron microscopy suggest a wall-membrane interaction stabilizing the cell envelope. The chemical and physical properties of this type of cell envelope would appear to form the basis for a new major division of bacteria with the definitive characteristics of a morphologically distinct subunit cell wall devoid of peptidoglycan.

Amino Acids↗
PubMed1992

Comparison of cell-wall teichoic acid with high-molecular-weight extracellular slime material from Staphylococcus epidermidis.

Extracellular high-mol.-wt material was separated from liquid cultures of Staphylococcus epidermidis. This material contained protein c. 20% w/w and polysaccharide c. 80% w/w. The polysaccharide was isolated by gel and ion-exchange chromatography and contained glycerol phosphate, glucose, N-acetylglucosamine, and D-alanine. Cell-wall teichoic acid was isolated from strain RP-62A and had a similar composition.

Acetylglucosamine↗
PubMed1988

[Immunomodulating properties of the antigens of the cell walls of nontoxigenic Corynebacterium diphtheriae].

The total protein fraction was obtained by extraction with nonionic detergent NP-40. The fraction composition and molecular parameters were studied with DDS-Na electrophoresis in polyacryl amide gel. Common properties of the Corynebacterium diphtheriae protein fraction 66 kD and an analogous fraction of the cell walls of staphylococci and the measles virus were shown with immunoblotting. Cell-mediated mechanisms of the immune response to contact with antigens of Corynebacterium diphtheriae cell walls were revealed.

Adjuvants, Immunologic↗
PubMed1971

Abnormal autolytic enzyme in a pneumococus with altered teichoic acid composition.

Pneumococci in which the choline component of the cell wall teichoic acid was replaced by ethanolamine contain an abnormal autolytic enzyme that has a low molecular weight and low activity in contrast to the enzyme typical of choline-containing bacteria that has a high molecular weight and high activity. The abnormal autolysin can be converted to the normal (cholinetype) enzyme by incubation in vitro with choline-containing cell walls.

Amino Alcohols↗
PubMed2000

Compressive/Tensile Stresses and Lignified Cells as Resistance Components in Joints between Cladodes of Opuntia laevis (Cactaceae).

The Cactaceae are a diverse group of plants with a wide variety of morphologies. Many species of Opuntia have segmented stems in which terminal cladodes may be separated from main-stem cladodes with varying amounts of resistance. From a geometric approach, derivations were used to calculate normal (axial and bending) and shear (transverse force and torque) stresses at joints due to the weight of the cladodes. Normal and shear stresses act perpendicular and parallel to (along) the cross sections of joints, respectively. Normal stress caused by bending was >10 times that of the mean value of any other stress. Analyses were performed to determine the relationship between maximum normal stress and the amount of lignified xylem cells. Such cells had thicker cell walls compared with the various other cells of stem joints that had thin cell walls and that thus would provide the most resistance to normal stresses. An analogy was made between cactus joints and a composite beam with reinforcing rods. In such joints, thin-walled parenchyma cells might be analogous to concrete that has little resistance to tensile stress, while the thick-walled, lignified xylem cells would be analogous to reinforcing rods. There were statistically significant relationships between normal stresses (from bending and axial loads) and mean percentage of lignified xylem cells (r=0.73) and between normal stresses and total areas of lignified xylem cells (r=0.65) (more stress, more reinforcing xylem cells). Tensile portions of cactus joints had 23% lignified xylem cells, while compressive portions had only 10% lignified xylem cells in joint areas (more tension, more reinforcing xylem cells). In addition, tensile joint tissues had two to three times more thick-walled, lignified xylem cells in the outer 30% of the radius compared with other joint tissues types (more reinforcing near the surface). To our knowledge, this is the first publication to present mechanical stresses at stem joints of cacti and the first to relate these stresses to characteristics of resisting tissues in the joints of a cactus.

Journal Article↗
PubMed2003

Down-regulation of the AtCCR1 gene in Arabidopsis thaliana: effects on phenotype, lignins and cell wall degradability.

Cinnamoyl CoA reductase (CCR; EC 1.2.1.44) is the first enzyme specific to the biosynthetic pathway leading to monolignols. Arabidopsis thaliana (L.) Heynh. plants transformed with a vector containing a full-length AtCCR1 cDNA in an antisense orientation were obtained and characterized. The most severely down-regulated homozygous plants showed drastic alterations to their phenotypical features. These plants had a 50% decrease in lignin content accompanied by changes in lignin composition and structure, with incorporation of ferulic acid into the cell wall. Microscopic analyses coupled with immunolabelling revealed a decrease in lignin deposition in normally lignified tissues and a dramatic loosening of the secondary cell wall of interfascicular fibers and vessels. Evaluation of in vitro digestibility demonstrated an increase in the enzymatic degradability of these transgenic lines. In addition, culture conditions were shown to play a substantial role in lignin level and structure in the wild type and in the effects of AtCCR1 repression efficiency.

Aldehyde Oxidoreductases↗
PubMed1980

[Isolation and characterization of endo-N-acetylmuramidase produced by Actinomyces levoris].

Precipitation by ammonium sulfate and a subsequent purification of the culture fluid of Actinomyces levoris by gel-filtration through Sephadex G-25, ion-exchange chromatography on DEAE-cellulose and CM-cellulose resulted in an enzyme which activley lyzes the cell walls of a hemolytic streptococcus of group A. The molecular weight (12,500), isoelectric point (pI 10,6) and amino acid composition of the enzyme were determined. The enzyme specificity was assayed using peptidoglycane isolated rom the cell walls of streptococcus of group A used as a substrate. An analysis of the hydrolysis products of peptidoglycane showed that the enzyme under study is an endo-beta-N-acetylmuramidase (EC 3.2.1.17).

Actinomyces↗
PubMed1965

ROLE OF AMINO ACIDS IN POSTEXPONENTIAL GROWTH.

Toennies, Gerrit (Temple University, and The Institute for Cancer Research, Philadelphia, Pa.). Role of amino acids in postexponential growth. J. Bacteriol. 90:438-442. 1965.-It was shown earlier that depletion of different essential amino acids from the medium of growing Streptococcus faecalis leads to the formation of cell types of different compositions in terms of cytoplasm, wall, and membrane. The findings presented now indicate that these postexponential effects can be induced by very low concentrations of incomplete amino acid complements, that cystine and methionine have major and separate effects, and that these effects may be modulated differentially by the presence of different combinations of other amino acids.

Amino Acids↗
PubMed1973

A polypeptide bacteriophage receptor: modified cell wall protein subunits in bacteriophage-resistant mutants of Bacillus sphaericus strain P-1.

Bacillus sphaericus strain P-1 has previously been shown to have a tetragonally arrayed (T layer) protein which forms the outer layer of the cell wall. The T layer was quantitatively extracted from whole cells by 6 M urea, and the T layer subunits were purified by electrophoresis of the extracts on acrylamide gels containing 0.1% sodium dodecyl sulfate or 6 M urea. Using ethylene diacrylate cross-linked gels, the T layer was found to make up 16% of the total cellular protein. A virulent bacteriophage which is inactivated by purified T layer was isolated from soil. Twenty-four phage-resistant mutants were isolated, of which 17 had T layer subunits of increased mobility on sodium dodecyl sulfate acrylamide gels. No mutants devoid of T layer were found. Mutants were grouped into six classes according to the molecular weight of their T layer subunits. These ranged from that of the wild type, 150,000 down to 86,000. Two mutants from different classes were examined in detail. Cells of the mutant strains did not adsorb phage nor did cell walls isolated from these mutants inactivate phage. The amino acid composition of the T layers from mutants differed little from that of the wild-type T layer.

Adsorption↗
PubMed1968

Passive electrical properties of microorganisms. 3. Conductivity of isolated bacterial cell walls.

The dielectric properties of isolated Micrococcus lysodeikticus cell walls have been studied to establish more firmly the view that wall-associated ions play a major role in the conduction of low frequency electric current by intact bacterial cells. The conductivity of isolated walls was found to be about 0.40 mho/m. If counterions associated with fixed, ionized groups in the wall have average mobilities equal to that of sodium ions in free solution, the fixed charge concentration required to account for the measured conductivity is between 75 and 95 meq/liter of wet wall volume. Estimates of the numbers of titratable amino and carboxyl groups in wall polymers indicate that conductivity is more closely related to net wall charge than to total wall charge. The measured wall conductivity was used to predict a value of 0.15 +/- 0.03 mho/m for whole cell conductivity. This prediction is close to the measured value of 0.25 +/- 0.05 mho/m and it is thought that much of the disparity in values is related to changes in wall structure and composition during the isolation procedures.

Aging↗
PubMed2000

Biosynthesis of the galactan component of the mycobacterial cell wall.

The structural core of the cell walls of Mycobacterium spp. consists of peptidoglycan bound by a linker unit (-alpha-L-Rhap-(1-->3)-D-GlcNAc-P-) to a galactofuran, which in turn is attached to arabinofuran and mycolic acids. The sequence of reactions leading to the biogenesis of this complex starts with the formation of the linker unit on a polyprenyl-P to produce polyprenyl-P-P-GlcNAc-Rha (Mikusová, K., Mikus, M., Besra, G. S., Hancock, I., and Brennan, P. J. (1996) J. Biol. Chem. 271, 7820-7828). We now establish that formation of the galactofuran takes place on this intermediate with UDP-Galf as the Galf donor presented in the form of UDP-Galp and UDP-Galp mutase (the glf gene product) and is catalyzed by galactofuranosyl transferases, one of which, the Mycobacterium tuberculosis H37Rv3808c gene product, has been identified. Evidence is also presented for the growth of the arabinofuran on this polyprenyl-P-P-linker unit-galactan intermediate catalyzed by unidentified arabinosyl transferases, with decaprenyl-P-Araf or 5-P-ribosyl-PP as the Araf donor. The product of these steps, the lipid-linked-LU-galactan-arabinan has been partially characterized in terms of its heterogeneity, size, and composition. Biosynthesis of the major components of mycobacterial cell walls is proving to be extremely complex. However, partial definition of arabinogalactan synthesis, the site of action of several major anti-tuberculosis drugs, facilitates the present day thrust for new drugs to counteract multiple drug-resistant tuberculosis.

Cell Wall↗