Wall Polysaccharides Research Articles

Growth and cell wall changes in azuki bean epicotyls I. Changes in wall polysaccharides during intact growth

o) was the shortest in the upper region (0-30 mm below the apex) of the epicotyl, where vigorous endogenous growth took place, and became longer toward the basal region, which was mature and not growing. In the upper region of the epicotyl, a lower percentage of a-cellulose and a higher percentage of pectic substances than in the lower region were found. The percentage of hemicellulose content was almost constant over the whole epicotyl. Major components of noncellulosic neutral sugars in the cell wall were galactose and xylose. The percentage of the galactose content to the noncellulosic polysaccharide was highest in the upper region and lowest in the basal region of the epicotyl, and a clearly negative correlation between the galactose composition and the T o value was obtained. On the contrary, the percentage of die xylose content was highest in the basal region and lowest in die upper region, and a clearly positive correlation between die xylose composition and the To value was obtained. During die endogenous growth of die intact epicotyl, all die neutral sugars, particularly galactose, increased in die upper region, whereas in die middle and basal regions, only xylose increased. Similar changes in sugar compositions were observed during IAA-induced elongation of die segment excised from various regions of die epicotyl.

Feulgen, iron-propionocarmine and cupra-ammonium in preparing algal chromosomes for light microscopy.

A method for obtaining algal chromosomal preparations is described employing the Feulgen method for DNA staining, Fe-propionocarmine as an enhancing stain, and cupra-ammonium to remove cell wall material. Fe-propionocarmine applied as a gradient to the side provides cells stained with the Feulgen stain alone or with the Feulgen Fe-propionocarmine stain, thereby facilitating useful comparison. Where dilute the Fe-propionocarmine enhances nuclear staining without staining orthe organelles; where more concentration it also stains the nucleolus, spindle, spindle polar bodies, pyrenoid and protoplast. Treatment with cupra-ammonium, to remove polysaccharide wall material, followed by neutralization with propionocarmine, enables thinner squashes and better chromosome spreads without loss of differential staining. Preparations mounted in euparal are long-lasting.

Lytic activity of the plasmalemma and its derivatives in plant cells

Ultrastructural, cytochemical and densitometrical investigation carried out on suspension culture cells of Haplopappus gracilis, protoplasts isolated from leaf parenchyma cells of Nicotiana tabacum, root meristem, root cap cells and young leaves of Hordeum seedlings revealed a pronounced lytic capacity of plasmalemma evaginations and invaginations. In cultivated cells plasmalemma outgrowths into the cell walls exhibited high acid phosphatase activity; presumably, they are important for separation of the aggregated cells. The lytic activity of plasmalemma infoldings seen in cultivated cells increased if the cells were transferred to a medium lacking carbohydrate. In starved cells plasmalemma evaginations protruding into the wall isolated wall fragments which underwent lysis (fig. 1). The degraded wall material captured by plasmalemma invaginations was then transferred to the central vacuole. It is suggested that in this way wall polysaccharides become mobilized allowing a partial survival of the cell population even after 4-day's carbon starvation. During the endocytic process the cytoplasmic islets are included into plasmalemmasomes; so these structures may be identified as auto-heterophagosomes (ambilysosomes by de Duve).

Further observations on cell wall morphogenesis and polysaccharide arrangement during plant growth

The three-dimensional arrangement of the polysaccharide chains in cell walls was investigated, using ultracryotomy and cytochemistry, in order to test the validity of the previously postulated “ordered fibril hypothesis” and to analyze the characteristics of the primary wall morphogenesis. Both in mung bean hypocotyl (Phaseolus aureus) and pea root (Pisum sativum) cultured in defined conditions, cell to cell endogenous specificity is marked by differences in the numbers of layers, thickness, rhythm and direction of deposition. The occurrence of bow-shaped arrangements and of strata of orientation intermediate between the main crisscrossed multifibrillar layers suggests that the sequential changes of the morphogenetic activity of the cells is progressive. The twisted polysaccharide disposition evokes certain mesomorphic states; a part of the mechanism responsible for the wall arrangement may result from a self-assembly process as in the orientation of the molecules in a liquid cristal. This possibility finds experimental support in the fact that a three-dimensional association of the hemicellulose chains spontaneously appears when precipitated in acellular conditions. Polysaccharide removal associated with shadowing indicates that the ordered disposition within the wall is extensively altered by even a slight extraction. These data may invalidate diverse results which are generally brought forward to explain the wall organization during growth.

Polysaccharide and oligosaccharide changes in germinating lupin cotyledons

In germinating lupin cotyledons, there was a rapid depletion of raffinose series oligosaccharides, a temporary increase in sucrose and constant low levels of reducing monosaccharides. The major polysaccharide fraction was extracted with hot NH4 oxalate—EDTA solution and had the constitution of intercellular/cell wall polysaccharide. GLC examination of component sugars showed that as cotyledons expanded this fraction was depleted and that there was selective hydrolysis of arabinose and galactose, so that the uronic acid proportion increased. Gel and DEAE-cellulose chromatography showed that this fraction became more heterogeneous. The neutral and acidic fractions were separated and the component sugars, viscosities, gel chromatographic behaviour and sedimentation constants of these determined. The results indicated that in the later phase of plant cell wall expansion in germinating lupin cotyledons the arabinogalactan side chains of the pectic polysaccharide fraction are selectively hydrolysed leaving a primary wall with a high uronic acid content.

Structural-metabolic polysaccharides of Rhodotorula

1. One of the polysaccharides of the cell walls of the species ofRhodotorula studied in a structuralmetabolic (soluble) glucomannan with a glucose: mannose ratio averaging 1:2.5.

Flokulace a obsah polysacharidů v buněčné stěně kvasinek při kontinuální výrobě piva.

Flokulace a obsah polysacharidů v buněčné stěně kvasinek při kontinuální výrobě piva.

Wall teichoic acids in animal Staphylococcus aureus strains determined by precipitation.

567 strains of Staphylococcus aureus isolated from a number of animal hosts were examined by agar gel precipitation for wall teichoic acids or other wall polysaccharides. The species was shown to be heterogeneous with regard to these constituents. Three groups could be distinguished: 1. The strains which had been classified biochemically as belonging to the human, bovine, hare and horse biotypes, and some of the swine strains, contained polysaccharide A. Of these, the horse strains contained polysaccharide Aα whereas the other strains regularly contained polysaccharide Aß. Of the latter, a higher incidence of additional polysaccharide Aα distinguished the human biotype from other biotypes. 2. The dog strains contained none of the reference polysaccharides but an unknown polysaccharide (P). 3. The pigeon and mink strains contained polysaccharide C. The occurrence of polysaccharide C in the biochemically least active biotypes is interesting, indicating a bridge towards the polysaccharide AßC group of S. epidermidis.

Mode of action of clotrimazole.

Clotrimazole, a synthetic antifungal agent, was fungicidal to growing cultures of one strain of Candida albicans. Cultures treated with the drug were osmotically stable. It had no effect on the respiratory activity of intact C. albicans cells or their isolated mitochondria with exogenous NADH and succinate as substrates. Studies with radioactive precursors revealed that clotrimazole inhibited synthesis of both protein and RNA by intact cells to a greater extent than that of DNA, lipid and wall polysaccharides. However, even with higher levels of the drug, the effect on endogenous or poly U-directed polypeptide synthesis by cell-free extracts was consistently negative. The minimum fungicidal concentration of the drug caused a marked enhancement of leakage of intracellular phosphorus compounds into the ambient medium with concomitant breakdown of cellular nucleic acids. Acceleration of K-efflux in treated cells also occurred to the corresponding extent. Both of these events began rapidly and extensively aft...

A function of the Golgi apparatus in polysaccharide synthesis and transport in the root-cap cells of wheat.

1. A radioautographic study of the cells of the root tips of wheat incubated with d-[1- or 6-(3)H]glucose has shown that labelled material is formed in the golgi apparatus of the root-cap cells. This material passed to the vesicles associated with the golgi bodies and then moved through the cytoplasm across the plasmalemma and was incorporated into the cell wall and slime layer of the tissue. 2. Analysis of the labelled material extracted from the root tips showed that the bulk of the radioactive material was polysaccharide; there were relatively small amounts of labelled lipids and protein in the tissue. 3. Starch was formed from the exogenous labelled glucose and it was located in the plastids of the cell. The synthesis of starch depended on the metabolic activity of the cells, which varied with the position of the cell in the various tissues of the root tip and with the amount of the exogenous glucose. 4. Isolation of the radioactive polysaccharides from the root tip incubated in the radioactive glucose has shown that the glucose was very rapidly incorporated into the galactosyl residues of the polymers. 5. Analysis of the radioactive polysaccharides has indicated that the material transported in the golgi vesicles is probably pectic substance. 6. A scheme for the synthesis of the storage and wall polysaccharides by separate routes and their location within the cell has been put forward.

MORPHOGENESIS AND BIOCHEMICAL PROCESSES IN SCHIZOPHYLLUM COMMUNE FR.

The investigation concerns a first attempt to unravel biochemical patterns of significance for morphogenesis in S. commune. The results derive from two different stocks: one with wild morphology, the other exhibiting an impairment of pileus formation. Some morphological and genetical features of the stocks are discussed. A special culture technique allowed fair synchronization and control of development via the medium. This technique is based on the fact that differentiation can be prevented by cultivation in a thiamine-free medium. Measured changes in protein, RNA, DNA, and soluble cell constituents during thiamine-induced primordia formation yielded some information concerning the first steps of differentiation. Primordial growth was found to depend upon transport of nitrogenous compounds from the mycelium and the presence of a carbon source in the medium. Most of the assimilated glucose is deposited as polysaccharides in the cell walls of the primordia. Chemical analysis of the cell walls demonstrated that they are mainly composed of two different glucans, called here S- and R-glucan, some properties of which were investigated. Pileus formation was shown to occur without the uptake of nutrients from the medium and to depend upon the withdrawal of substances from stunted fructifications and stroma in particular. Comparison of the two investigated stocks provided strong support for a causal relationship between degradation of the cell-wall glucans and pileus formation. An analysis was made of respiration and fermentation during development; some findings probably bearing upon the problem of morphogenesis are discussed.

Electron microscopy of Neurospora crassa mycelia.

The fine structure of vegetative mycelia of the filamentous Ascomycete, Neurospora crassa, has been investigated by the standard techniques of electron microscopy. Addition of uranyl nitrate to the methacrylate-embedding medium minimized disruption of the specimens-an accident often observed in the preparation of microbial material. This report describes the presence of a chitinous polysaccharide wall containing fine fibrils embedded in a homogeneous matrix. A sinuate plasma membrane lies adjacent to the inner wall surface. This membrane is often closely associated with the endoplasmic reticulum of the cytoplasm. Numerous mitochondria of the classical type, and dense particles of 10 mmicro diameter occur throughout the cytoplasm. The nuclear region is surrounded by a double membrane with pore openings. Associated with the nuclear envelope is a dense area, the nucleolus. The significance of these observations and their relationship to other forms is discussed.