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PubMed2005

Genome sequence of Blochmannia pennsylvanicus indicates parallel evolutionary trends among bacterial mutualists of insects.

The distinct lifestyle of obligately intracellular bacteria can alter fundamental forces that drive and constrain genome change. In this study, sequencing the 792-kb genome of Blochmannia pennsylvanicus, an obligate endosymbiont of Camponotus pennsylvanicus, enabled us to trace evolutionary changes that occurred in the context of a bacterial-ant association. Comparison to the genome of Blochmannia floridanus reveals differential loss of genes involved in cofactor biosynthesis, the composition and structure of the cell wall and membrane, gene regulation, and DNA replication. However, the two Blochmannia species show complete conservation in the order and strand orientation of shared genes. This finding of extreme stasis in genome architecture, also reported previously for the aphid endosymbiont Buchnera, suggests that genome stability characterizes long-term bacterial mutualists of insects and constrains their evolutionary potential. Genome-wide analyses of protein divergences reveal 10- to 50-fold faster amino acid substitution rates in Blochmannia compared to related bacteria. Despite these varying features of genome evolution, a striking correlation in the relative divergences of proteins indicates parallel functional constraints on gene functions across ecologically distinct bacterial groups. Furthermore, the increased rates of amino acid substitution and gene loss in Blochmannia have occurred in a lineage-specific fashion, which may reflect life history differences of their ant hosts.

Amino Acid Sequence↗
PubMed1992

Purification of maize pollen exines and analysis of associated proteins.

Zea mays (maize) pollen exines have been purified with the use of differential centrifugation and sucrose gradients, followed by mild detergent and high salt treatment. The final exine fraction is highly purified from other organelles and subcellular structures as assayed by transmission electron microscopy. Using mature maize pollen as the starting material, 0.2 to 0.3% of the total pollen protein remained associated with the exine fraction throughout the purification. Seven abundant sodium dodecyl sulfate-extractable proteins are detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the final fraction. Amino acid analysis reveals that one of the proteins contains a substantial amount of hydroxyproline, a characteristic of some primary cell wall proteins. The amino acid composition of the 25-kD protein strongly implies that it is an arabinogalactan protein. When exines are purified from earlier pollen developmental stages, a subset of the proteins found in the mature pollen exine is seen.

Journal Article↗
PubMed1992

Cell Wall Changes in Nectarines (Prunus persica) : Solubilization and Depolymerization of Pectic and Neutral Polymers during Ripening and in Mealy Fruit.

Nectarine fruit (Prunus persica L. Batsch var nectarina [Ait] maxim) cultivar Fantasia were either ripened immediately after harvest at 20 degrees C or stored for 5 weeks at 2 degrees C prior to ripening. Fruit ripened after 5 weeks of storage did not soften to the same extent as normally ripened fruit, they lacked juice, and had a dry, mealy texture. Pectic and hemicellulosic polysaccharides were solubilized from the mesocarp of the fruit using phenol:acetic acid:water (PAW) treatment to yield PAW-soluble material and cell wall material (CWM). The carbohydrate composition and relative molecular weight (M(r)) of polysaccharide fractions released from the CWM by sequential treatment with cyclohexane-trans-1,2-diamine tetra-acetate, 0.05 m Na(2)CO(3), 6 m guanidinium thiocyanate, and 4 m KOH were determined. Normal ripening of nectarines resulted in solubilization of pectic polymers of high M(r) from CWM during the first 2 d at ripening temperatures. Concurrently, galactan side chains were removed from pectic polymers. Solubilized pectic polymers were depolymerized to lower M(r) species during the latter stages of ripening. Upon removal from cool storage, fruit had undergone some pectic polymer solubilization, and after ripening, pectins were not depolymerized and were of high M(r). Side chains did not appear to be removed from insoluble pectic polymers and branched pectins accumulated in the CWM. The molecular weight profiles obtained by gel filtration of the hemicellulosic fractions from normally ripening and mealy fruit were similar. The results suggest that mealiness results as a consequence of altered pectic polymer breakdown, including that associated with neutral side chains.

Journal Article↗
PubMed2007

Apoplastic barriers to radial oxygen loss and solute penetration: a chemical and functional comparison of the exodermis of two wetland species, Phragmites australis and Glyceria maxima.

Few studies have examined exodermal development in relation to the formation of barriers to both radial oxygen loss (ROL) and solute penetration along growing roots. Here, we report on the structural development, chemical composition and functional properties of the exodermis in two diverse wetland grasses, Glyceria maxima and Phragmites australis. Anatomical features, development, the biochemical composition of exodermal suberin and the penetration of apoplastic tracers and oxygen were examined. Striking interspecific differences in exodermal structure, suberin composition and quantity per unit surface area, and developmental changes along the roots were recorded. Towards the root base, ROL and periodic acid (H(5)IO(6)) penetration were virtually stopped in P. australis; in G. maxima, a tight ROL barrier restricted but did not stop H(5)IO(6) penetration and the exodermis failed to stain with lipidic dyes. Cultivation in stagnant deep hypoxia conditions or oxygenated circulating solution affected the longitudinal pattern of ROL profiles in G. maxima but statistically significant changes in exodermal suberin composition or content were not detected. Interspecific differences in barrier performance were found to be related to hypodermal structure and probably to qualitative as well as quantitative variations in suberin composition and distribution within exodermal cell walls. Implications for root system function are discussed, and it is emphasized that sufficient spatial resolution to identify the effects of developmental changes along roots is crucial for realistic evaluation of exodermal barrier properties.

Cell Wall↗
PubMed1982

In situ analysis of the inflammatory cell infiltrates in colon carcinomas and in the normal colon wall.

Inflammatory cells (lymphocytes, plasma cells, macrophages, mast cells and polymorphonucleated cells) forming infiltrates in the stroma of ten colon carcinomas were analysed in situ and compared with the cells of the normal colon wall. The cancer stroma contained a larger proportion of lymphocytes, while the number of IgA-containing plasma cells was markedly reduced compared to the normal colon mucosa from the resection edge. In both tissues the number of macrophages was much higher than the study of H & E stained routine preparations would suggest. The peritumoural cell infiltrates consisted of 47% lymphocytes, 19% plasma cells, 15% macrophages (including monocytes) and 5% granulated mast cells, while 15% of all inflammatory cells were polymorphonucleated (PMN). Necrotic areas of the tumours were dominated by a larger number of PMN and macrophages. Compared to the normal colon wall, the significant differences in cell composition and the accumulation of mononuclear cells (MC) at the cancer borders indicate that populations of cells are selectively attracted to the tumour site, although the factors responsible for the local cell reaction in cancer are still unknown.

Adenocarcinoma↗
PubMed2006

The two-component regulatory system mtrAB is required for morphotypic multidrug resistance in Mycobacterium avium.

Clinical isolates of the opportunistic pathogen Mycobacterium avium complex (MAC) undergo a reversible switch between red and white colony morphotypes on agar plates containing the lipoprotein stain Congo red. Compared to their isogenic red counterparts, white morphotypic variants are more virulent and more resistant to multiple antibiotics. This report shows that the two-component regulatory system mtrAB is required for the red-to-white switch as well as for other morphotypic switches of MAC. A mutant with a transposon insertion in the histidine protein kinase gene mtrB was isolated from a morphotypically white parent clone. The mutant resembled a naturally occurring red morphotypic variant in that it stained with Congo red, was sensitive to multiple antibiotics, and was permeable by a fluorescent DNA stain. However, it differed from a red variant in that it could not switch to the white or transparent morphotype, and it could not survive intracellularly within macrophage-like cells. Transcomplementation with a cloned wild-type mtrB gene restored to the mutant the ability to form impermeable, drug-resistant white and transparent variants. Quantitative reverse transcriptase PCR showed that mtrB was required for the normal expression of cell surface Mce proteins, some of which are up-regulated in the red-to-white switch. The results indicate that mtrAB functions in regulating the composition and permeability of mycobacterial cell walls and plays a role in the reversible colony type switches of MAC.

ATP-Binding Cassette Transporters↗
PubMed1991

Mucor dimorphism.

Mucor dimorphism has interested microbiologists since the time of Pasteur. When deprived of oxygen, these fungi grow as spherical, multipolar budding yeasts. In the presence of oxygen, they propagate as branching coenocytic hyphae. The ease with which these morphologies can be manipulated in the laboratory, the diverse array of morphopoietic agents available, and the alternative developmental fates that can be elicited from a single cell type (the sporangiospore) make Mucor spp. a highly propitious system in which to study eukaryotic cellular morphogenesis. The composition and organization of the cell wall differ greatly in Mucor yeasts and hyphae. The deposition of new wall polymers is isodiametric in yeasts and apically polarized in hyphae. Current research has focused on the identity and control of enzymes participating in wall synthesis. An understanding of how the chitosome interacts with appropriate effectors, specific enzymes, and the plasma membrane to assemble chitin-chitosan microfibrils and to deposit them at the proper sites on the cell exterior will be critical to elucidating dimorphism. Several biochemical and physiological parameters have been reported to fluctuate in a manner that correlates with Mucor morphogenesis. The literature describing these has been reviewed critically with the intent of distinguishing between causal and casual connections. The advancement of molecular genetics has afforded powerful new tools that researchers have begun to exploit in the study of Mucor dimorphism. Several genes, some encoding products known to correlate with development in Mucor spp. or other fungi, have been cloned, sequenced, and examined for transcriptional activity during morphogenesis. Most have appeared in multiple copies displaying independent transcriptional control. Selective translation of stored mRNA molecules occurs during sporangiospore germination. Many other correlates of Mucor morphogenesis, presently described but not yet explained, should prove amenable to analysis by the emerging molecular technology.

Carbon↗
PubMedDate not supplied

[Amino acid composition of peptidoglycans isolated from cells of Coryneform bacteria by various methods].

A comparative study has revealed the identity of the amino acid composition of the peptide part of peptidoglycans obtained from the intact cells (the first method) and of the amino acid composition of peptidoglycans isolated from cell walls (the second method). This evidences for the possibility of using the first method when determining types of peptidoglycans for diagnosis of the coryneform bacteria genera.

Actinomycetales↗
PubMed1986

Resistance vessels in hypertension.

Hypertension differentially affects the functional behavior of the mesenteric resistance arteries compared with similar sized arteries from the cerebral vascular autoregulatory bed. Antihypertensive drug treatment may, or may not, reverse the vascular wall structural composition and smooth muscle cell receptor sensitivity and contractile properties. These effects depend on the agent used, the length of treatment, and the vascular bed. Rat brain resistance arteries are myogenic at transmural pressures that are similar to those measured in autoregulatory, in vivo flow studies, as is the elevation of this range as a consequence of hypertension. The methods we have developed afford the investigator quantitative control over the variables that might affect the function of resistance vessels when tested in vitro. These techniques maintain the vessel close to physiological, in vivo conditions, and are useful tools for unraveling the complex mechanisms that define both, the normal vessel properties, and those of the vessel which has undergone modifications as a result of hypertension. Whether the vascular changes that we find in the SHR rat model parallel those which occur in human essential hypertension must yet be ascertained.

Animals↗
PubMed1985

[The chemical composition of "zymosans" from yeasts].

The chemical composition of "Zymosanes" (complex cell-wall-polysaccharides), prepared by different methods from Baker's yeast, were analyzed by classical and modern techniques, e.g. GLC and TLC. They are very complex natural products consisting of a basic structure of polysaccharides, which proteins and different lipids are bound to. Higher purified zymosanes seem to be free from nucleic acids and do not contain sialic acid.

Amino Acids↗
PubMedDate not supplied

Macrophage interaction with mycobacteria including M. leprae.

Resistance properties of pathogenic mycobacteria to macrophage bactericidal activity seems to be due mostly to the composition and constitution of their cell walls. In the case of Mycobacterium tuberculosis, sulfatides and polyglutamic acid could be implicated in the phenomenon of fusion inhibition between phagosomes and lysosomes. M. leprae and M. lepraemurium, which do not seem to inhibit fusions are protected by a thick electron transparent zone (ETZ) that seems to be composed of mycosides. This layer would inhibit lysosomal enzyme diffusion inside phagosomes. As ETZ does not exist in mycobacteria before their phagocytosis, we have tried to see when and how it is formed inside macrophages. We have compared ETZ formation in M. leprae and M. avium which both contain mycosides. These two species were allowed to be phagocytized by mouse bone-marrow derived macrophage and samples were taken for electron microscopy during the first hours of phagocytosis and also during several weeks of incubation. In M. avium ETZ appeared within 1 to 2 hours after phagocytosis. It seems to be formed by a sort of swelling of the thin electron transparent layer of the bacterial cell wall. This swelling occurs only in regions where the external polysaccharide layer of M. avium starts to disappear. After 1 to 3 hours, this layer was completely absent and all bacteria were enveloped in a thick ETZ. In M. leprae, the ETZ is also formed within one hour after ingestion. However, the presence in some bacteria of a very thin dense layer located at the original place of the outer dense layer of the cell wall does not fit well with the idea of ETL swelling. In addition, the appearance of a thick dense layer located between the ETZ and the phagosome membrane is not yet understood. The ETZ formed also rapidly in macrophages infected with heat killed cells of M. avium or M. leprae. This shows that its formation does not require the active participation of the bacterium. As already proposed ETZ seems to lessen considerably the diffusion of lysosomal enzymes towards the bacterium in both species. In M. leprae it seems especially efficient because despite acid phosphatase activity found in many phagosomes, neither the number of bacteria per macrophage nor their state of degradation changed during 3 and a half months of macrophage culture.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

[Taxonomic position of cultures of the family Micromonosporaceae].

The paper describes cultures that can be assigned to the genus Micropolyspora according to such properties as the presence of aerial mycelium, catenae of spores and galactose in the composition of sugars in the cell wall. However, the cultures contain xylose in the cell wall and therefore are related to the genus Micromonospora. These findings as well as the atypical proportion between DAPA and its isomers suggest that the cultures occupy an intermediate position between the genus Micromonospora and the genus Micropolyspora.

Micromonospora↗
PubMed1967

Preparation and chemical composition of the cell membranes of developmental reticulate forms of meningopneumonitis organisms.

The outer limiting membranes of developmental reticulate forms of the meningopneumonitis organism were purified by a combination of differential centrifugation, trypsin digestion, and sodium dodecyl sulfate treatment, and their physical and chemical properties were compared with those of outer envelopes of mature dense forms of this organism. Reticulate bodies were easily disrupted by short periods of sonic treatment and were lysed by trysin digestion, in contrast to the dense bodies which were resistant to these treatments. In electron micrographs, reticulate body membranes were seen as very thin, flattened structures, whereas dense-body envelopes showed folding rigid membranes. The results of chemical fractionation of (32)P-labeled purified preparations indicated that reticulate body membranes have smaller amounts of phospholipid, and are more dense than cell walls of the mature forms. The analysis of amino acid composition of reticulate body cell membranes showed that they do not contain cystine or methionine, both of which were found in cell walls of dense bodies. These results clearly show that there are significant differences in the chemical and physical properties of the outer envelopes of the developmental and mature forms of this organism.

Acids↗
PubMed1999

Almost pure I(alpha) cellulose in the cell wall of Glaucocystis.

Crystalline features of cellulose microfibrils in the cell walls of Glaucocystis (Glaucophyta) were studied by combined spectroscopy and diffraction techniques, and the results were compared with those of Oocystis (Chlorophyta). Although these algae are grouped into two different classes, by the composition of their chloroplasts for instance, their cell walls are quite similar in size and morphology. The most striking features of their cellulose crystallites are that they have the highest cellulose I(alpha) contents reported to date. In particular, the I(alpha) fraction of cellulose from Glaucocystis was found to be as high as 90% from (13)C NMR analysis. The mode of preferential orientation of cellulose crystallites in their cell walls is also interesting; equatorial 0.53-nm lattice planes were oriented parallel to the cell surface in the case of Glaucocystis, while the 0.62-nm planes were parallel to the Oocystis cell surface. Such a structural variation provides another link to the evolution of cellulose structure, biosynthesis, and its biocrystallization mechanism.

Cell Wall↗
PubMed1984

[Electron microscopic findings in A-cells of the islands of Langerhans in diabetes mellitus].

A description is given of the electron microscopic-morphometric findings obtained for the islets of Langerhans of the pancreas and for the glucagon-producing A cells of one patient suffering from longstanding insulin-dependent diabetes mellitus (IDDM, type I diabetes), two patients with longstanding insulin-independent diabetes mellitus (NIDDM, type II diabetes), and one non-diabetic. A morphometric determination of the volume densities of the vascular connective tissue and the various endocrine cells per islet tissue and organelles/ultrastructures per A cell was made, and the diameters of the A-granules were measured. So far, no such studies have been made for human diabetes mellitus, and only a few are available for humans with sound metabolism. In general, the qualitative and, particularly, the quantitative electron microscopic results found for the IDDM patient show greater and clearer deviation from the control with normal metabolism than the findings obtained for the NIDDM patients. As regards the cellular composition of the pancreatic islets and changes caused by diabetes mellitus, the morphometric values obtained from electron micrographs are in essential agreement with comparable findings reported in the literature for light microscopic-histochemical and -immunohistochemical morphometry. The patient with insulin-dependent diabetes has a higher proportion of vascular connective tissue in the pancreatic islets than the non-diabetic. This increase is both relative and absolute and is primarily connected with the loss of B cells in this type of diabetes. In the IDDM patient, A cells were found in the islets but also scattered as single cells in the exocrine tissue and in the walls of pancreatic ductules. The ultrastructural composition of the A cells varies within wide limits even in persons with sound metabolism. Diabetes mellitus does not cause major qualitative alterations in the A cells. The A cells of the IDDM patient contained a remarkable number of nuclei and rarely showed A-granule crinophagia. The casuistic electron microscopic findings, most of which have been obtained for the first time, are discussed. Nothing can be said at this stage about the general applicability of the findings. The morphometric results obtained for the A cells can be interpreted as indicating increased metabolism with heightened glucagon synthesis and secretion in the case of the insulin-dependent diabetic and, to a lesser extent, in the NIDDM patients. This interpretation would support the assumption of a normally existing mutual local paracrine regulation of the A and B cells which stems from close topographical relations (contact, gap junctions).

Adolescent↗
PubMed1985

Peptidoglycan cross-linking and teichoic acid attachment in Streptococcus pneumoniae.

Autolysin-defective pneumococci continue to synthesize both peptidoglycan and teichoic acid polymers (Fischer and Tomasz, J. Bacteriol. 157:507-513, 1984). Most of these peptidoglycan polymers are released into the surrounding medium, and a smaller portion becomes attached to the preexisting cell wall. We report here studies on the degree of cross-linking, teichoic acid substitution, and chemical composition of these peptidoglycan polymers and compare them with normal cell walls. peptidoglycan chains released from the penicillin-treated pneumococci contained no attached teichoic acids. The released peptidoglycan was hydrolyzed by M1 muramidase; over 90% of this material adsorbed to vancomycin-Sepharose and behaved like disaccharide-peptide monomers during chromatography, indicating that the released peptidoglycan contained un-cross-linked stem peptides, most of which carried the carboxy-terminal D-alanyl-D-alanine. The N-terminal residue of the released peptidoglycan was alanine, with only a minor contribution from lysine. In addition to the usual stem peptide components of pneumococcal cell walls (alanine, lysine, and glutamic acid), chemical analysis revealed the presence of significant amounts of serine, aspartate, and glycine and a high amount of alanine and glutamate as well. We suggest that these latter amino acids and the excess alanine and glutamate are present as interpeptide bridges. Heterogeneity of these was suggested by the observation that digestion of the released peptidoglycan with the pneumococcal murein hydrolase (amidase) produced peptides that were resolved by ion-exchange chromatography into two distinct peaks; the more highly mobile of these was enriched with glycine and aspartate. The peptidoglycan chains that became attached to the preexisting cell wall in the presence of penicillin contained fewer peptide cross-links and proportionally fewer attached teichoic acids than did their normal counterparts. The normal cell wall was heavily cross-linked, and the cross-linked peptides were distributed equally between the teichoic acid-linked and teichoic acid-free fragments.

Amino Acids↗
PubMed1972

Peptidoglycan composition and taxonomy of group D, E, and H streptococci, and Streptococcus mutans.

The qualitative and quantitative composition of the peptidoglycan from the cell wall of groups D, E, and H streptococci, and Streptococcus mutans, was determined. In group D, S. faecalis and the closely related species S. liquefaciens and S. zymogenes were separated from S. faecium and the closely related species S. durans on the basis of their peptidoglycan composition. A relationship among S. bovis, S. equinus, and some strains of S. mutans was indicated by the presence in each of a similar peptidoglycan containing threonine. Threonine was released from the S. mutans polymer as a threonine-lysine dipeptide. Hydrolysis of the dipeptide at 100 C for 24 hr in 6 n HC1 was required to break the peptide bond. Motile group D streptococci possessed a peptidoglycan of the same composition as S. faecium. Group E and H strains were also similar in the composition of their peptidoglycan. The results demonstrate that peptidoglycan composition can be used to (i) aid in the division of members of an immunological group into subgroups, and (ii) indicate a relationship between members of the same genus which are not related on an immunological basis.

Amino Acids↗
PubMed1983

Host-Pathogen Interactions : XXII. A Galacturonic Acid Oligosaccharide from Plant Cell Walls Elicits Phytoalexins.

Elicitors of phytoalexin accumulation in soybean (Glycine max L. Merr., cv Wayne) cotyledons were released from soybean cell walls and from citrus pectin by partial acid hydrolysis. These two hydrolysates yielded nearly identical distributions of elicitor activity when fractionated on anion-exchange columns. Chromatography of the pectin elicitor on gel filtration and high-pressure anion-exchange columns did not further purify the elicitor. Elicitor activity of the preparation was lost by treatment with either endo-alpha-1,4-polygalacturonase or pectate lyase. Glycosyl residue compositions of the purified elicitors from cell walls and pectin were both found to be approximately 98% galacturonosyl residues. Linkage analysis of the pectin elicitor showed that most, if not all, of the galacturonosyl residues were alpha-1,4-linked. The high-mass molecular ions detected by fast atom bombardment-mass spectrometry of the most active elicitor fractions from cell walls and pectin both corresponded precisely to a molecule composed of 12 galacturonosyl residues. These results suggest that dodeca-alpha-1,4-d-galacturonide is the active elicitor, but the possibility remains that the active component could be a slightly modified oligogalacturonide present, but not detected, in the purified fractions.

Journal Article↗