Vegetative Cell Wall Research Articles

Oral vegetable granuloma: ultrastructural and histological study

An unusual giant-cell granulomatous inflammatory oral lesion is characterised by the presence of hyaline rings and by a lack of agreement on their nature, opinions ranging from their being hyaline degenerative blood-vessels to remains of leguminous cells. Ten such lesions and a variety of vegetables have been examined in the present investigation. Light-microscopical examination of the lesions revealed the hyaline rings surrounded by inflamed granulation tissue with associated multinuclear giant cells. Electron-microscopical examination showed them to consist of a material similar to that of vegetable cell walls, sometimes with an associated superficial layer of collagen. The observations indicate that the lesions consist of vegetable remains with an associated foreign-body type of inflammatory response.

OCCURRENCE AND PHYLOGENETIC SIGNIFICANCE OF “SPECIAL WALLS” AT MEIOSPOROGENESIS IN COLEOCHAETE

Within germinating zygotes of Coleochaete pulvinata, meiospores are individually surrounded by chamber walls which are ultrastructurally and chemically different from vegetative cell walls of the same species. Meiospore chamber walls exhibit the staining reactions typical of callose. They thus resemble the “special walls” present during sporogenesis in embryophytes. Their presence suggests that the charophycean green algal ancestors of land plants may have possessed spore development preadaptations influential in the evolution of walled spores, an important plant adaptation to terrestrial life.

Silicon accumulation in fronds of the ostrich fern, Matteuccia struthiopteris

Silicon accumulation in Matteuccia struthiopteris (L.) Todaro was investigated by electron microscopy and X-ray microanalysis. Silicon levels were highest in petioles of mature vegetative leaves, where it was restricted largely to the walls of epidermal and collenchymatous tissues. The pattern of silicon distribution within these walls was random and at no time were electron-dense aggregates of spherical particles observed. The absence of silicon from immature cells indicates that this element accumulated in vegetative cell walls during final stages of development. Moreover, the lack of silicon in lignified cell walls suggests that conditions suitable for lignification in ferns are incompatible with silicon deposition.

H2, N2, and O2 metabolism by isolated heterocysts from Anabaena sp. strain CA.

Metabolically active heterocysts isolated from wild-type Anabaena sp. strain CA showed high rates of light-dependent acetylene reduction and hydrogen evolution. These rates were similar to those previously reported in heterocysts isolated from the mutant Anabaena sp. strain CA-V possessing fragile vegetative cell walls. Hydrogen production was observed with isolated heterocysts. The ratio of C2H4 to H2 produced ranged from 0.9 to 1.2, and H2 production exhibited unique biphasic kinetics consisting of a 1 to 2-min burst of hydrogen evolution followed by a lower, steady-state rate of hydrogen production. This burst was found to be dependent upon the length of the dark period immediately preceding illumination and may be related to dark-to-light ATP transients. The presence of 100 nM NiCl2 in the growth medium exerted an effect on both acetylene reduction and hydrogen evolution in the isolated heterocysts from strain CA. H2-stimulated acetylene reduction was increased from 2.0 to 3.2 mumol of C2H4 per mg (dry weight) per h, and net hydrogen production was abolished. A phenotypic Hup- mutant (N9AR) of Anabaena sp. strain CA was isolated which did not respond to nickel. In isolated heterocysts from N9AR, ethylene production rates were the same under both 10% C2H2-90% Ar and 10% C2H2-90% H2 with or without added nickel, and net hydrogen evolution was not affected by the presence of 100 nM Ni2+. Isolated heterocysts from strain CA were shown to have a persistent oxygen uptake of 0.7 mumol of O2 per mg (dry weight) per h, 35% of the rate of whole filaments, at air saturating O2 levels, indicating that O2 impermeability is not a requirement for active heterocysts.

A histochemical study of Corallina officinalis (Rhodophyta, Corallinaceae)

Abstract A branch of Corallina officinalis L. consists of (1) an apical meristem of intensely active cells, (2) intergenicula of small, calcite encased, vegetative cells, and (3) uncalcified genicula made up of long cells. Histochemical analyses were carried out to examine developmental and structural changes in apical, intergenicular and genicular tissues with regard to the occurrence of pectins, starch, cellulose, protein, CaCO3 and nucleic acids. Vegetative cell walls consist of an inner cellulosic layer and a thicker middle layer composed of a pectin-like substance and CaCO3. The end walls of intergenicular cells are unusually rich in cellulose. A stratified cuticle covering all calcified surfaces is secreted by underlying cells. It is pectin-like and protein-free and made up of highly compressed layers over epithallial cells and more loosely compacted layers over branch apices. Starch deposition progresses centripetally in the intergenicular medulla. The uncalcified parts of genicular cells produce c...

The isolation and chemical composition of the zygospore cell wall of chlamydomonas reinhardii

After mating of competant haploid cells the diploid zygote formed could be matured into a zygospore. Isolation of the cell walls of the zygospore followed by chemical analysis indicated that the protein content was approx. 5%. Amino acid analysis showed the cell walls to contain hydroxyproline in substantial quantities (about 6 mol% of the total amino acids). The neutral sugars found were arabinose, mannose, galactose, glucose with trace amounts of rhamnose and xylose. The glucose accounted for approx. 50% of the total sugars. Twenty five percent (by weight) of the cell wall was unaccounted for, possibly remaining insoluble during the hydrolysing procedures. The results were compared with those obtained previously for the vegetative cell wall and are discussed with reference to the change from the haploid to the diploid state.

Location of peptidoglycan lytic enzymes in Bacillus sphaericus

The level of three peptidoglycan hydrolases was determined in the mother cell compartment and forespores of Bacillus sphaericus. Vegetative and sporulating cells contained in LD-carboxypeptidase active only on the vegetative cell wall peptidoglycan, and we have previously shown that sporulation is accompanied by the production of two new enzymes active only on the spore cortex peptidoglycan. These gamma-D-glutamyl-meso-diaminopimelate endopeptidase and a meso-diaminopimelate-D-alanine dipeptidase. The LD-carboxypeptidase activity appeared to be located in the membranes of both the mother cells and forespores. Endopeptidase activity was located in the integument fraction of the forespores, and the dipeptidase activity was only found in the forespore cytoplasm. These different locations comply with the probable different functions of these enzymes.

Ultrastructure of plasmodesmata and cross walls inCephaleuros, PhycopeltisandTrentepohlia(Chroolepidaceae; Chlorophyta)

Cross walls in Cephaleuros, Phycopeltis and Trentepohlia contain simple plasmodesmata approximately 40–50 nm in diameter. In all three genera, the plasmodesmata generally occur in only the central portion of the cross wall, thus forming a “central pit”. In the cross walls between vegetative cells of Phycopeltis, a ring of lightly stained material within a thickened border encircles the central pit. The cross walls between vegetative cells in Cephaleuros and Trentepohlia specimens examined thus far clearly lack the distinct arrangement characteristic of Phycopeltis; however, the cross walls between the zoosporangium and pedicel (i.e. the zoosporangium-pedicel septa) in Cephaleuros, Phycopeltis and Trentepohlia contain an inner ring of wall material which encircles the central pit. Despite some similarity between such septa and the cross walls of Phycopeltis vegetative cells, the latter are morphologically distinct. Ultrastructural observations clearly indicate that the central pits of the Chroolepidaceae a...

CELL WALL CHEMISTRY AND ULTRASTRUCTURE OF CHLOROCOCCUM OLEOFACIENS (CHLOROPHYCEAE)1,2

ABSTRACT Cell walls of Chlorococcum oleofadens Trainor & Bold were examined ultrastructurally and chemically. The wall of zoospores has a uniform 30 nm width and a regular lamellar pattern. Zoospores and young vegetative cell walk exhibit periodicities, consisting of 20 nm ridges on the outer layer. Vegetative cell walls have a variable thickness of Up to 800 nm and are composed of multiple layers of electron dense material. Further, vegetative walk contain a microfibrillar material composed predominantly of glucose and presumed to be cellulose. Except for this cellulose, vegetative cell wall chemistry is very similar to that of Chlamydomemas being composed of glycoprotein rich in hydroxyproline. The hydroxyproline in Chlorococcum walls is linked glycosidically to a mixture of hetrooligosaccharides composed of arabinose and galactose, and in one instance, an unknown 6‐deoxyhexose. Altogether, the glycoprotein complex accounts for at least 52% of the wall. The amino acid composition of the walls is stikingly similar to those of widely different plant species. Indirect evidence indicates zoospore cell walls are also chemically similar to those of Chlamydomonas, and like them, are cellulose free. Thus a major chemical difference between zoospore and vegetative cell walk of Chlorococcum is the presence of cellulose in the latter. The contribution of this microfibrillar cellulose to the physical properties of the vegetative wall is discussed.

Extent of cross-linking of germ cell wall of a variant of Bacillus cereus

Summary The extent of cross-linking of diaminopimelic acid in germ cell wall peptidoglycan of Bacillus cereus var. alesti spores [strain A(−)], was found to be 13.5 ± 2.1%. This contrasted with a value of 40.3 ± 2.25% for the extent of cross-linking of vegetative cell wall of this organism. These data indicate that germ cell wall may be considerably less rigid than vegetative cell wall. The extent of cross-linking of germ cell wall and vegetative cell wall of a cortexless mutant, A(−)1, derived from A(−), were found to be 33.3 ± 3.2% and 42.6 ± 2.0% respectively. Apparently the cortexless mutant is altered in germ cell wall structure as well as in the ability to produce a cortex. Attempts were made to determine whether the extent of cross-linking of germ cell wall remained low in whole spores of A(−) and increased on germination, but these were inconclusive mainly because of problems associated with removal of hydrophobic spore coat protein.

The ultrastructure of reproduction in the brown algaPylaiella littoralis

The ultrastructure of the later stages of gametogenesis in plurilocular gametangia ofPylaiella littoralis is described. Following a series of cell divisions, a large number of cells are present in the gametangium, each one delineated by a cell wall, and all enclosed within original vegetative cell walls. Paramural bodies are common during the division stages. Flagellum and mastigoneme formation, which occur after the period of cell division, are the major ultrastructural events in later stages of gametogenesis. Developing mastigonemes were observed in the perinuclear continuum and in ER cisternae. Mastigonemes were not observed in Golgi cisternae, although it is believed that they do occur there and that this stage was not observed. Flagella are formed in vesicles in the cytoplasm. The later stages of gametogenesis in plurilocular gametangia are compared to similar stages in plurilocular reproductive structures from diploid plants, which indicates an essentially similar pattern of development for both. A comparison is made between flagellum and mastigoneme formation in plurilocular gametangia ofPylaiella littoralis and in unilocular sporangia of the same species, which indicates that the processes are similar in both. A general pathway for development of mastigonemes inPylaiella is also suggested.

Distribution of peptidoglycan synthetase activities between sporangia and forespores in sporulating cells of Bacillus sphaericus.

Sporulating cells of Bacillus sphaericus 9602 containing fully engulfed forespores at different stages of maturity were broken by ultrasonic disruption, followed by grinding with alumina. In this way soluble enzymes derived mainly from the sporangial or from the forespore cytoplasms were obtained. Diaminopimelate ligase activity is required exclusively for cortical peptidoglycan synthesis, is absent during vegetative growth, and is synthesized during forespore maturation. It is found exclusively in the sporangial cytoplasm. L-lysine ligase is required for vegetative cell wall peptidoglycan synthesis but not for cortex synthesis. It is found in both fractions, but it has a fourfold higher specific activity in the forespore cytoplasm. Other enzymes that are required for synthesis of the nucleotide-pentapeptide precursors of both cortical and vegetative cell wall peptidoglycans are found in similar specific activities in both compartments. Mature spores, free of any residual sporangial material, have specific activities of all of these enzymes and of L-lysine ligase similar to those in forespores and in vegetative cells and are devoid of diaminopimelate ligase activity. Thus, the differential expression of at least one gene required for spore cortex synthesis in B. sphaericus occurs exclusively in the sporangial cytoplasm.

Effect of Endogenous and Exogenous Factors on the Primary Structures of Bacterial Peptidoglycan

Publisher Summary The chapter focuses on the assemble data, showing to what extent the primary structure of the peptidoglycan may change because of the effects of endogenous and exogenous factors. The chapter discusses the effects of endogenous factors such as (1) growth phase, (2) peptidoglycan structures of vegetative cell walls compared with the spore cortex, (2) changes in the peptidoglycan structure during a morphological life cycle, (4) genetic variations of the peptidoglycan structure. All of the alterations in the amino-acid sequence of peptidoglycan discussed so far are either insignificant or have been caused by unusual conditions such as growth inhibition or growth in unbalanced medium. More pronounced differences in the peptidoglycan under normal growth conditions, however, were found in bacilli during the transition from vegetative cell to endospore. In contrast to the peptidoglycan of vegetative cells, that of the spore cortex contains muramic lactam and exhibits a considerably lower degree of cross linkage. The chapter also discusses effects of exogenous factors such as (1) aerobic and anaerobic growth, (2) amino-acid composition of the growth medium, (3) ionic environment, (4) osmotic value of the growth medium, (5) antibiotics, and (6) growth-inhibiting concentrations of glycine and amino acids.

Cell wall polymers of Bacillus sphaericus: activities of enzymes involved in peptidoglycan precursor synthesis during sporulation.

In synchronously sporulating cells of Bacillus sphaericus 9602, the specific activities of those enzymes specifically required for the synthesis of the UDP-N-acetyl-muramyl-pentapeptide precursor of vegetative cell wall peptidoglycan decay by 50% after the end of exponential cell division, probably as a consequence of dilution by newly synthesized protein. The meso-diaminopimelate ligase is the only new activity whose synthesis is required for synthesis of the nucleotide-pentapeptide precursor of spore cortex peptidoglycan. The addition of d-Ala-d-Ala to the nucleotide tripeptide is catalyzed by an enzyme present in both vegetative and sporulating cells, which apparently does not discriminate between lysine- and diaminopimelate-containing acceptors. The activities of the l-Ala and d-Ala-d-Ala ligases and of the d-Ala-d-Ala synthetase increases in parallel with the appearance of the diaminopimelate ligase, indicating coordinate derepression and suggesting operon-like organization of the appropriate structural genes.

Appearance of a γ- d -Glutamyl-( l ) Meso -Diaminopimelate Peptidoglycan Hydrolase During Sporulation in Bacillus sphaericus

Particulate preparations from sporulating cells of Bacillus sphaericus 9602 contained an endopeptidase activity that hydrolyzed the gamma-d-glutamyl-(l)meso-diaminopimelic acid linkages found in the spore cortical peptidoglycan of this organism. Diaminopimelic acid did not occur in the vegetative cell wall peptidoglycan, and the gamma-d-glutamyl-l-lysine linkages found in this polymer were not hydrolyzed by the endopeptidase. The endopeptidase hydrolyzed (X)-l-alanyl-gamma-d-glutamyl-(l)meso-diaminopimelyl(l)-d-alanyl-d-alanine only after removal of the terminal d-alanine residue. The preparations contained an acyl-d-alanyl-d-alanine carboxypeptidase I activity which converted such pentapeptides into substrates for the endopeptidase and which was inhibited 50% by 4 x 10(-7) M benzylpenicillin. This activity also hydrolyzed the analogous pentapeptide substrates containing l-lysine. The preparations also contained an acyl-l-lysyl-d-alanine carboxypeptidase II activity that was not active on the meso-diaminopimelic acid-containing analogue. Neither this activity nor the endopeptidase was inhibited by 10(-3) M benzylpenicillin. The specificities of the carboxypeptidases were consistent with the exclusive presence of l-lysine C-termini in the vegetative peptidoglycan and of meso-diaminopimelyl-d-alanine C-termini in the spore cortical peptidoglycan of B. sphaericus 9602.

Amidation and Cross-Linking of the Enzymatically Synthesized Peptidoglycan of Bacillus stearothermophilus

Abstract A particulate enzyme system from Bacillus stearothermophilus which catalyzes the synthesis of peptidoglycan from uridine nucleotide precursors has been investigated. The preparation catalyzed extensive cross-linking of the enzymatically synthesized peptidoglycan. In addition in the presence of ATP and ammonia or l-glutamine amidation of the peptidoglycan also occurred. The nature of the amidated products obtained on lysozyme digestion of the enzymatically synthesized peptidoglycan was elucidated by a comparison with similar materials obtained after lysozyme digestion of isolated vegetative cell walls of this organism.

Structure of the peptidoglycan from vegetative cell walls of Bacillus subtilis.

Structure of the peptidoglycan from vegetative cell walls of Bacillus subtilis.

Composition of the cellular envelopes of Anabaena cylindrica.

Comparative chemical analyses were made of the walls of vegetative cells, heterocysts, and spores, and of the mucilage of Anabaena cylindrica. The wall of the vegetative cell is composed predominantly of amino compounds, with a mannose-rich carbohydrate component comprising only 18% of the dry weight. In contrast, 62% of the heterocyst wall and 41% of the spore wall is carbohydrate. The carbohydrate moieties of the heterocyst wall and spore wall are similar in that the ratio of glucose, mannose, galactose, and xylose is approximately 75:20:3:4 in both walls. It appears that, during the differentiation of a vegetative cell into either a spore or a heterocyst, a glucose-rich wall polysaccharide is produced that is different from the polysaccharide component of the wall of the vegetative cell and of the sheath. In the case of the heterocyst, the wall was estimated to account for approximately 52% of the dry weight of the whole cell.

Scale formation in chrysophycean algae. I. Cellulosic and noncellulosic wall components made by the Golgi apparatus.

The cell wall of the marine chrysophycean alga Pleurochrysis scherfellii is composed of distinct wall fragments embedded in a gelatinous mass. The latter is a polysaccharide of pectic character which is rich in galactose and ribose. These wall fragments are identified as scales. They have been isolated and purified from the vegetative mother cell walls after zoospore formation. Their ultrastructure is described in an electron microscope study combining sectioning, freeze-etch, and negative staining techniques. The scales consist of a layer of concentrically arranged microfibrils (ribbons with cross-sections of 12 to 25 x 25 to 40 A) and underlying radial fibrils of similar dimensions. Such a network-plate is densely coated with particles which are assumed to be identical to the pectic component. The microfibrils are resistant to strong alkaline treatment and have been identified as cellulose by different methods, including sugar analysis after total hydrolysis, proton resonance spectroscopical examination (NMR spectroscopy) of the benzoylated product, and diverse histochemical tests. The formation and secretion of the scales can be followed along the maturing Golgi cisternae starting from a pronounced dilated "polymerization center" as a completely intracisternal process which ends in the exocytotic extrusion of the scales. The scales reveal the very same ultrastructure within the Golgi cisternae as they do in the cell wall. The present finding represents the first evidence on cellulose formation by the Golgi apparatus and is discussed in relation to a basic scheme for cellulose synthesis in plant cells in general.

Isolation and characterization of three autolytic enzymes associated with sporulation of Bacillus thuringiensis var. thuringiensis.

Cells of Bacillus thuringiensis containing refractile spores autolyzed readily when suspended in buffer. The autolysate contained enzymes which lysed vegetative cell walls of the organism. Three enzymes were isolated from the autolysate, and each was purified approximately 30-fold. One enzyme, most active near pH 4.0, was found to be an N-acetylmuramidase. The other two enzymes exhibited pH optima at 8.5. One was stimulated by cobalt ions and the other was not. The cobalt-stimulated enzyme was shown to be an N-acetylmuramyl-l-alanine amidase. The cobalt insensitive enzyme exhibited both N-acetylmuramyl-l-alanine amidase and endopeptidase activity. The amidase activity may reflect incomplete separation of the cobalt-stimulated enzyme. The endopeptidase cleaved the peptide bond between l-alanine d-glutamic acid. A cell wall lytic endopeptidase with this specificity has not been previously reported. All three enzymes were extremely limited in the range of bacterial cell walls which they attacked. Except for cell walls of Micrococcus lysodeikticus, which were lysed by the muramidase, only cell walls of members of the genus Bacillus were attacked.