Polysaccharide Components Of Cell Walls Research Articles

Protective effects of peptides on the cell wall structure of yeast under osmotic stress.

Three peptides (LL, LML, and LLL) were used to examine their influences on the osmotic stress tolerance and cell wall properties of brewer's yeast. Results suggested that peptide supplementation improved the osmotic stress tolerance of yeast through enhancing the integrity and stability of the cell wall. Transmission electron micrographs showed that the thickness of yeast cell wall was increased by peptide addition under osmotic stress. Additionally, quantitative analysis of cell wall polysaccharide components in the LL and LLL groups revealed that they had 27.34% and 24.41% higher chitin levels, 25.73% and 22.59% higher mannan levels, and 17.86% and 21.35% higher β-1,3-glucan levels, respectively, than the control. Furthermore, peptide supplementation could positively modulate the cell wall integrity pathway and up-regulate the expressions of cell wall remodeling-related genes, including FKS1, FKS2, KRE6, MNN9, and CRH1. Thus, these results demonstrated that peptides improved the osmotic stress tolerance of yeast via remodeling the yeast cell wall and reinforcing the structure of the cell wall. KEY POINTS: • Peptide supplementation improved yeast osmotic stress tolerance via cell wall remodeling. • Peptide supplementation enhanced cell wall thickness and stability under osmotic stress. • Peptide supplementation positively modulated the CWI pathway under osmotic stress.

The evolving views of the simplest pectic polysaccharides: homogalacturonan

Pectin is an important component of cell wall polysaccharides and is important for normal plant growth and development. As a major component of pectin in the primary cell wall, homogalacturonan (HG) is a long-chain macromolecular polysaccharide composed of repeated α-1,4-D-GalA sugar units. At the same time, HG is synthesized in the Golgi apparatus in the form of methyl esterification and acetylation. It is then secreted into the plasmodesmata, where it is usually demethylated by pectin methyl esterase (PME) and deacetylated by pectin acetylase (PAE). The synthesis and modification of HG are involved in polysaccharide metabolism in the cell wall, which affects the structure and function of the cell wall and plays an important role in plant growth and development. This paper mainly summarizes the recent research on the biosynthesis, modification and the roles of HG in plant cell wall.

Using brefeldin A to disrupt cell wall polysaccharide components in rice and nitric oxide to modify cell wall structure to change aluminum tolerance.

The components and structure of cell wall are closely correlated with aluminum (Al) toxicity and tolerance for plants. However, the cell wall assembly and function construction in response to Al is not known. Brefeldin A (BFA), a macrolide, is used to disrupt cell wall polysaccharide components, and nitric oxide (NO), a signal molecule, is used to modify the cell wall structure. Pretreatment with BFA accelerated Al accumulation in root tips and Al-induced inhibition of root growth of two rice genotypes of Nipponbare and Zhefu 802, and significantly decreased the cell wall polysaccharide content including pectin, hemicellulose 1, and hemicellulose 2, indicating that BFA inhibits the biosynthesis of components in the cell wall and makes the root cell wall lose the ability to resist Al. The addition of NO donor (SNP) significantly alleviated the toxic effects of Al on root growth, Al accumulation, and oxidative damage, and decreased the content of pectin polysaccharide and functional groups of hydroxyl, carboxyl, and amino in the cell wall via FTIR analysis, while had no significant effect on hemicellulose 1 and hemicellulose 2 content compared with Al treatment. Furthermore, NO didn't change the inhibition effect of BFA-induced cell wall polysaccharide biosynthesis and root growth. Taken together, BFA disrupts the integrity of cell wall and NO modifies partial cell wall composition and their functional groups, which change the Al tolerance in rice.

Overexpression of UDP-glycosyltransferase genes enhanced aluminum tolerance through disrupting cell wall polysaccharide components in soybean

Overexpression of UDP-glycosyltransferase genes enhanced aluminum tolerance through disrupting cell wall polysaccharide components in soybean

Neochloris oleoabundans cell walls have an altered composition when cultivated under different growing conditions

The impact that environmental factors have on the intracellular components of microalgae has been the focus of research for a number of decades. Despite that, their effects on the cell wall have received very little attention. In this study, we investigated how different growing conditions affect the cell walls of N. oleoabundans. The results revealed that the cell wall composition varied in that the modifications were different in the four cultivation media: freshwater nitrogen-replete (optimum culture) and -depleted conditions, and seawater nitrogen-replete and -depleted conditions. Nitrogen deficiency in freshwater cultivation was the only condition that significantly (p < .05) increased the total content of carbohydrates in the cell wall. The three most abundant components of freshwater-cultivated cell wall polysaccharides were rhamnose, galactose and glucuronic acid whereas in seawater media the main components of cell wall polysaccharides were rhamnose, glucose and galactose. The combined results of the biochemical analyses and monoclonal antibodies epitope-binding revealed that N. oleoabundans cell walls are likely composed of sulphated polysaccharides enriched in mannose, β-(1 → 4)-d-mannans, and glucose as they grow in seawater. Salinity and nitrogen deficiency also had an impact on the nitrogenous components of the cell wall. Under these conditions we observed a decrease in glucosamine in the cell wall. The analysis of specific binding of monoclonal antibodies, revealed that the cell wall of N. oleoabundans is possibly enriched in arabinogalactan proteins (AGPs). Under salinity and nitrogen deficiency N. oleoabundans increased the proportion of the non-polar to polar amino acids in the cell walls. An increase of leucine in the cell walls may suggest that N. oleoabundans contains leucine-rich repeat proteins which are known to play a vital role in stress responses. This report provides new insights into microalgae cell wall biology and how cell walls are remodelled when growing under different conditions.

Identification of a dTDP-rhamnose biosynthetic pathway that oscillates with the molting cycle in Caenorhabditis elegans.

L-Rhamnose is a common component of cell-wall polysaccharides, glycoproteins and some natural products in bacteria and plants, but is rare in fungi and animals. In the present study, we identify and characterize a biosynthetic pathway for dTDP-rhamnose in Caenorhabditis elegans that is highly conserved across nematode species. We show that RML-1 activates glucose 1-phosphate (Glc-1-P) in the presence of either dTTP or UTP to yield dTDP-glucose or UDP-glucose, respectively. RML-2 is a dTDP-glucose 4,6-dehydratase, converting dTDP-glucose into dTDP-4-keto-6-deoxyglucose. Using mass spectrometry and NMR spectroscopy, we demonstrate that coincubation of dTDP-4-keto-6-deoxyglucose with RML-3 (3,5-epimerase) and RML-4 (4-keto-reductase) produces dTDP-rhamnose. RML-4 could only be expressed and purified in an active form through co-expression with a co-regulated protein, RML-5, which forms a complex with RML-4. Analysis of the sugar nucleotide pool in C. elegans established the presence of dTDP-rhamnose invivo Targeting the expression of the rhamnose biosynthetic genes by RNAi resulted in significant reductions in dTDP-rhamnose, but had no effect on the biosynthesis of a closely related sugar, ascarylose, found in the ascaroside pheromones. Therefore, the rhamnose and ascarylose biosynthetic pathways are distinct. We also show that transcriptional reporters for the rhamnose biosynthetic genes are expressed highly in the embryo, in the hypodermis during molting cycles and in the hypodermal seam cells specifically before the molt to the stress-resistant dauer larval stage. These expression patterns suggest that rhamnose biosynthesis may play an important role in hypodermal development or the production of the cuticle or surface coat during molting.

Use of FT-IR Spectra and PCA to the Bulk Characterization of Cell Wall Residues of Fruits and Vegetables Along a Fraction Process

This study focuses on the analysis of polysaccharide residues from the cell walls of fruits and vegetables: tomato, potato, pumpkin, carrot and celery root. An alcohol-insoluble residue was prepared from plant material by extraction using the hot ethyl alcohol method and then cell wall fractions soluble in trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetate, sodium carbonate and alkaline solution were sequentially extracted. Infrared spectroscopy combined with Fourier transform (FT-IR) was used to evaluate differences among cell wall residues and among species after each step of sequential extraction of pectins and hemicelluloses. Additionally, pectic substances were identified using an Automated Wet Chemistry Analyser. Principal component analysis (PCA) was applied to FT-IR spectra in two regions: 1,800–1,200 cm−1 and 1,200–800 cm−1 in order to distinguish different components of cell wall polysaccharides. This method also allowed us the possibility of highlighting the most important wavenumbers for each type of polysaccharide: 1,740, 1,610 and 1,240 cm−1 denoting pectins or 1,370 and 1,317 cm−1 denoting hemicelluloses and cellulose, respectively.

Characterisation of polysaccharides from gold kiwifruit ( Actinidia chinensis Planch. ‘Hort16A’)

The cell-wall polysaccharide components of gold kiwifruit ( Actinidia chinensis Planch. ‘Hort16A’, ZESPRI ® GOLD) have been investigated for the first time. Alcohol-insoluble residues (AIRs) were prepared from whole, unpeeled gold and green ( Actinidia deliciosa) kiwifruit and the constituent sugar and glycosyl linkage compositions determined. AIRs from both kiwifruit contained a high proportion of cellulose; the gold kiwifruit contained a higher proportion of hemicellulosic polysaccharides and lower proportion of pectic polysaccharides compared with the green. The gold kiwifruit AIR was partitioned by sequential extraction with water, aqueous CDTA (0.05 M), aqueous Na 2CO 3 (0.05 M) and aqueous KOH (1 M then 4 M). The glycosyl linkage compositions of each fraction were determined and the types of cell-wall polysaccharides from the gold fruit were found to be similar to those previously reported for the green fruit.

Metagenomic islands of hyperhalophiles: the case of Salinibacter ruber

BackgroundSaturated brines are extreme environments of low diversity. Salinibacter ruber is the only bacterium that inhabits this environment in significant numbers. In order to establish the extent of genetic diversity in natural populations of this microbe, the genomic sequence of reference strain DSM 13855 was compared to metagenomic fragments recovered from climax saltern crystallizers and obtained with 454 sequencing technology. This kind of analysis reveals the presence of metagenomic islands, i.e. highly variable regions among the different lineages in the population.ResultsThree regions of the sequenced isolate were scarcely represented in the metagenome thus appearing to vary among co-occurring S. ruber cells. These metagenomic islands showed evidence of extensive genomic corruption with atypically low GC content, low coding density, high numbers of pseudogenes and short hypothetical proteins. A detailed analysis of island gene content showed that the genes in metagenomic island 1 code for cell surface polysaccharides. The strain-specific genes of metagenomic island 2 were found to be involved in biosynthesis of cell wall polysaccharide components. Finally, metagenomic island 3 was rich in DNA related enzymes.ConclusionThe genomic organisation of S. ruber variable genomic regions showed a number of convergences with genomic islands of marine microbes studied, being largely involved in variable cell surface traits. This variation at the level of cell envelopes in an environment devoid of grazing pressure probably reflects a global strategy of bacteria to escape phage predation.

Effect of raw and cooked onion dietary fibre on the antioxidant activity of ascorbic acid and quercetin

The effect of cell walls (dietary fibre) from raw and cooked onions ( Allium cepa L. red skinned variety) on two dietary antioxidants, l-ascorbic acid (AA) and quercetin, was investigated. Cell walls isolated from onion parenchyma tissues were incubated with AA or quercetin in HEPES buffer at pH 6.5 and 37 °C for 2 h. The resulting supernatants were analysed by the ferric reducing antioxidant power (FRAP) assay and cyclic voltammetry (CV). Results show that onion cell walls effectively reduced AA degradation, but provided no protective effect against quercetin degradation, and may increase the degradation. This suggests some type of favourable interaction of the cell wall components with AA but not with quercetin. Cooking facilitates the extraction of cell wall polysaccharides and hence influences the extent of interaction of cell wall components and antioxidants. The redox behaviour of the antioxidants, the polysaccharide components of cell walls, and their relative extractabilities all appear to have important influences on the interactions.

Maize Stem Tissues: Impact of Development on Cell Wall Degradability

Grass degradability declines as cell wall and lignin concentrations increase during maturation. The role of tissue development and lignification in decline of stem degradability was examined in maize (Zea mays L.) internodes sampled at 10 stages of growth from early elongation through plant physiological maturity. The fourth elongated internode above ground level was collected from three maize hybrids grown in a 2‐yr, replicated field trial at St. Paul, MN. Internode cross‐sections and ground samples were incubated in vitro for 24‐ and 96‐h with rumen microbes. Tissue degradation was examined by light microscopy and degradability of cell wall polysaccharide components from ground internodes was determined. All tissues in elongating internodes were completely degradable except for protoxylem vessels, which was the only lignified tissue. After elongation, degradability of all tissues declined markedly except for phloem, which never lignified. Tissues with thick, lignified secondary walls (sclerenchyma and rind‐region parenchyma) required longer incubation times for observable degradation. Cell wall polysaccharide components were highly degradable in immature internodes, but degradability declined after elongation and reached a minimum by Sampling Date 8, with glucose and xylose residues having the greatest reductions in degradability. Cell wall polysaccharide degradation was related to lignin concentration and ferulate cross‐linking in a complex manner.

An original chemoenzymatic route for the synthesis of β- d-galactofuranosides using an α- l-arabinofuranosidase

Galactofuranose is a widespread component of cell wall polysaccharides in bacteria, protozoa and fungi, but is totally absent in mammals. Importantly, galactofuranose is a key constituent of major cell envelope polysaccharides in pathogenic mycobacteria. In this respect, galactofuranose-based glycoconjugates are interesting target molecules for drug design. O-Glycosidases and notably β- d-galactofuranosidases could be useful tools for the chemoenzymatic synthesis of galactofuranosides, but to date no studies of this type have been reported. Here we report the use of a GH 51 α- l-arabinofuranosidase for the synthesis of β- d-galactofuranosides. We have demonstrated that this enzyme can catalyse both the autocondensation of p-nitrophenyl-β- d-galactofuranoside and the transgalactofuranosylation of benzyl α- d-xylopyranoside, forming p-nitrophenyl β- d-galactofuranosyl-(1→2)-β- d-galactofuranoside and benzyl β- d-galactofuranosyl-(1→2)-α- d-xylopyranoside, respectively. Both reactions were very regiospecific and the reaction involving benzyl α- d-xylopyranoside afforded very high yields (74.8%) of the major product. To our knowledge, this demonstration of chemoenzymatic synthesis of galactofuranosides constitutes the very first use of an O-glycosidase for the synthesis of galactofuranosides.

A Study of Surface Proteins, Other Adhesins and Iron Acquiring Mechanisms in the Pathogenesis of Neisseria gonorrhoea strains Isolated from STD Patients in Ethiopia

Background information: Neisseria gonorrhoea is one of the most world wide prevalent Gram-negative diplococci bacteria causing the disease called Sexually Transmitted Disease on humans. Its stages of infection involve, first, colonization of columnar epithelial cells of mucosal surfaces; then an inflammatory response is elicited; and finally, the phagocytosis of the organisms by PMNs results in the formation of purulent discharges where the PMNs are found accumulated in it. The antigenic composition of N.gonorrhoea is complex with three major classes that are associated with the surface layers, namely, the pilus protein antigens, the polysaccharide component of cell wall and the outer membrane protein constitution. The pathogenicity determinant factors of N.gonorrhoea have been proved to include: Colonial Morphology which indicates that the virulence factors are based on the five major colony forms designated as T1, T2, T3, T4 and T5, indicating differences in surface antigens, virulence and in colony appearances; and, the Pili are the other pathogenesis determinant factors that are functioning by having adherence to the mucosal cell surface and serving as conjugal transfer of genetic material. It has been observed that piliated bacterial strains are resistant to phagocytosis, giving inefficient digestion ability to the macrophages compared to nonpiliated strains. Thus, types T1 and T2 are most virulent to humans because they are the piliated (fimbriated) strains. The Ethiopian situation in relation to gonococcal infections indicates that it is known to be highly prevalent among both sexes of most age groups. However no work has been conducted to assess the prevalence of the different virulence factors of N.gonorrhoeae strains. Objective : The aim of this study was thus to assess the prevalence of all the essential surface antigens as virulence factors of N.gonorrhoeae among the most vulnerable group of individuals for the infection and try to assess and recommend the possibility of getting important surface components to serve as vaccine candidates against gonococcal infections. Patients & methods: a total of over 300 STD male and female patients from three study sites, Addis Ababa, Nazareth, and Awassa, were used as study subjects by collecting urogenital specimen after their clinical examination. The specimens were then used for the isolation of the N.gonorrhoea strains that were identified for their virulence types, tested for their antimicrobial sensitivity patterns and determined their surface antigenic components for the most prevalent virulence factors using haemagglutination and other detection assay methods. Results: It was found that out of the total 335 specimens, N.gonorrhoea strains were isolated in 59% positive rate from males compared to the 43% positive rate was obtained from the females. The sensitivity pattern of these strains indicate that there were 19 different antibiogram patterns showing that only 12.3% were sensitive to all drugs while over 70% of the strains were resistant against more than two combined drugs and above 90% of these multi-drug resistant strains showed to be PPNGs. Out the total N.gonorrhoea isolates, 200 were tested for their haemagglutination and Iron-binding protein production properties and 35% of them were found to be Mannose Resistant Haemagglutinating (MRHA) strains while 20% were Mannose Sensitive Haemaggluintating (MSHA) strains when tested using the human AB blood types of. By the use guinea pig blood cells this was found to be 15% MRHA and 25% MSHA strains. When tested for their iron-binding protein (IBP) production, the MRHAs were positive for IBPs while the MSHA were positive for this property in 10%. Finally, based on the results obtained conclusions and recommendations are given at the end of the paper. [J Ethiopia Med Pract. 2002;4(1):14– 20]

Regulation of cell-wall polysaccharide components by CaCl2 in suspension cultures of kidney bean (Phaseolus vulgaris)

We cultured the suspension cells of kidney bean in MS media supplemented with one of five concentrations of CaCI2 [0,22,44 (control), 88, or 176 mg/L], and harvested them at the logistic (15 d) and early-stationary (30 d) phases. Cells grown at concentrations higher than 22 mg/L showed better proliferation than those at 0 mg/L The rate of proliferation also increased with higher concentrations. We fractionated the individual sugars into symplastic (EtOH and starch) and apoplastic (low-molecular pectin, high-molecular pectin, hemicellulose, and cellulose) components. Cells treated at the highest concentration (176 mg/L) exhibited the greatest amount of sugar in the EtOH and starch fraction during the logistic phase. In contrast, cells in the early stationary phase had the highest level of sugar at treatment concentrations of less than 22 mg/L. For treatment concentrations higher than 22 mg/L on Day 15, more pectin and hemicellulose was detected at greater amounts compared with those cells treated with 0 mg/L. However, at Day 30, concentrations higher than 44 mg/L induced greater amounts of pectin and hemicellulose than from the other concentrations. Cellulose was more abundant with the 0 mg/L treatment, and contents ranged from 17.4 to 25.5% in the primary cell walls over all treatment concentrations. These results indicate that CaCI2 modulates both symplastic and apoplastic sugar metabolism. Therefore, we suggest that the cell-wall structure may define the mode of polysaccharide biosynthesis during cell growth.

Impact of lignin composition on cell-wall degradability in anArabidopsis mutant

An Arabidopsis mutant that does not deposit syringyl-type lignin was used to test the hypothesis that lignin composition impacts cell-wall degradability. Two lines of the ferulate-5-hydroxylase-deficient fah1 mutant and the wild-type control line were grown in the greenhouse. In Experiment 1, the plants were harvested at the mature seed stage. For Experiment 2, plants were harvested 5, 6, 7 and 8 weeks after sowing. In both experiments stems were collected and analysed for cell-wall concentration and composition, and in vitro degradability of cell-wall polysaccharide components by rumen micro-organisms. The absence of syringyl-type lignin was confirmed for the mutant lines by nitrobenzene oxidation and pyrolysis-GC-MS. Lignin concentration was the same for all three Arabidopsis lines, at all stages of maturity. The Arabidopsis stems were similar to forage legumes in that the potentially degradable cell-wall fraction was very quickly degraded. Cell-wall polysaccharide degradability did not differ among the Arabidopsis lines in the first experiment after 24-h fermentations, but the cell-wall polysaccharides of the fah1-2 mutant line were less degradable after 96-h than either the wild-type or the fah1-5 mutant. In contrast, in Experiment 2 no differences among lines were found for cell-wall polysaccharide degradability after either 24- or 96-h fermentations; however, signficantly higher levels of ester-bound ferulic acid were found in the walls of the fah1 mutant lines. As expected, increasing stem maturity was correlated with reduced degradation of cell-wall polysaccharides. These experiments indicate that either lignin composition, as measured by syringyl-to-guaiacyl ratio, does not alter cell-wall degradability in Arabidopsis, or that the fah1 mutation has other effects on the cell walls of these mutants such that the impact of the change in syringyl-to-guaiacyl ratio is masked. © 1999 Society of Chemical Industry

Cell wall composition and degradability of stem tissue from lucerne divergently selected for lignin and in vitro dry‐matter disappearance

AbstractLucerne populations that had previously been divergently selected for acid detergent lignin (ADL) concentrations of whole herbage were additionally divergently selected for in vitro dry‐matter disappearance (IVDMD) of basal stems. Parental plants of the four selected populations were intercrossed and the half‐sib progeny evaluated in a replicated field trial in 1988 over two harvests. Cell wall composition of basal stems was determined for detergent fibre components and neutral sugars, uronic acids, Klason lignin and esterified and etherified phenolic acids of the total fibre fraction. Lignin polymer composition was measured by nitrobenzene oxidation. Degradability of cell wall polysaccharide components was determined by a 48‐h in vitro ruminal fermentation. Cell wall composition was changed by both selection criteria. Klason lignin proportion of the total fibre did not differ as a result of selection, whereas the ADL concentration of neutral detergent fibre was different among selection groups. The cell wall polysaccharides of lucerne basal stems shifted towards more cellulose (glucose residues) and less hemicellulose (xylose residues) with selection for either low ADL or high IVDMD. While degradability of the cell wall polysaccharides was correlated with various measures of lignin composition and concentration, the results were variable and inconclusive. Surprisingly, Kiason lignin and ADL were positively correlated with cell wall polysaccharide degradability, and esterified ferulic acid was negatively correlated with degradation of the cell wall. Selection for herbage ADL and basal stem IVDMD of lucerne did alter cell wall degradation, but the associated changes in cell wall lignification were not consistently correlated with cell wall degradability.

The fluorescence brightener Rylux BSU induces dimorphism in Basidiobolus ranarum.

The fluorescence brightener Rylux BSU (RBSU) showed an affinity for polysaccharide components of cell walls and accumulated in the extension zones of hyphal apices in Basidiobolus ranarum. It inhibited the polarized growth of mycelial hyphae and induced isotropic growth resulting in spherical thick-walled cells up to 456 microm in diameter. On the inner cell wall surface, massive protuberances were formed. The cell wall and protuberances were positive in PAS and the Grocott method and stained with fluorochromes Blankophor BA, Calcofluor, Uvitex 2B, Rylux BSU and FITC-labeled WGA- and ConA-lectins. The WGA-FITC fluorescence intensity of the wall's outermost layer, if not connected with neighbouring cells, and the fluorescence intensity of the innermost layer and of some protuberances mainly in their apical parts were on the average twice higher than the fluorescence intensity of the remaining wall material. RBSU binding to the cell wall material was stable. The process of converting from polarized to isotropic growth was reversible, depending upon contact with RBSU-containing medium. Repeated transfers of cells from RBSU-containing medium to an RBSU-free medium resulted in the development of apical swollen dumbbell-shaped cells.

The detection and quantification of apiose by capillary gas chromatography of its alditol acetates

The branched-chain sugar, apiose [3-C-(hydroxymethyl)-D-glycero-aldotetrose] occurs widely in plants, in low molecular weight glycosides’, and as a component of cell-wall polysaccharides’-s. Problems have been encountered in the analysis of apiose as its alditol acetate derivatives. For example, when pyridine was used as the acetylation catalyst6, the alditol gave two peaks by g.1.c.‘. Similar results were obtained when sodium acetate was used as the catalyst*, and underacetylation was suggested*. We have reported’ the application to apiose of the method of Blakeney et al.“, which uses reduction with sodium borohydride in methyl sulphoxide and acetylation catalysed by IV-methylimidazole. The two peaks detected were assigned to apiitol tetraand penta-acetate and reflected the slow acetylation “g’* of the tertiary hydroxyl group at C-3. Complete acetylation requires elevated temperatures and extended times (90 min)‘. Kindel and Cheng13 obtained similar results, but reported that substantial proportions of 3-C-(acetoxymethyl)-1,2,4tri-O-acetyl-3-O-(methylthiomethyl)-D-glycero-tetritol were formed as a side product. We now present additional evidence that application of the method of Blakeney et al.” to apiose gives apiitol 1,2,3,4,4’-penta-acetate and 1,2,4,4’-tetra-acetate, and propose a method for quantification based on the latter derivative.

Immunochemical and structural analysis of the cell wall mannan as the basis of the taxonomic reidentification of a yeast strain

The immunochemical properties and structural features of D-mannans from two Candida parapsilosis strains were studied. Weak cross-reactivity of D-mannans with antisera produced to C. parapsilosis strains was observed, as well as significant differences in the mannans structures were found by means of methylation analysis, acetolysis and 1H-NMR spectroscopy. In view of the discrepancies found, new taxonomic identification of one strain was carried out. On the basis of assimilation of potassium nitrate and formation of hat-shaped spores as well as other differences found by investigation of physiological characteristics, one strain of C. parapsilosis was reidentified as Hansenula anomala. This work demonstrates that immunochemical and structural investigations of cell-wall polysaccharide components can serve as a basis for taxonomic identification of yeast strains.

Cellular and Extracellular Polysaccharides of the Blue green AlgaNostoc

The carbohydrate content of various cellular fractions of the blue-green alga Nostoc was studied as a function of age of the culture. The production of extracellular and intracellular polysaccharides was higher in actively growing cultures. Mannose and glucose were the main components of cell wall polysaccharides. Glucosamine and diaminopimelic acid were also detected in the cell walls. The kinetics of incorporation of radioactivity from sodium [l4C] bicarbonate showed that the extra cellular polysaccharides were labelled within 10 min of incubation suggesting the active exudation of polysaccharides by this alga. The selective excretion of polysaccharides by the alga Nostoc is also suggested.