Determination of Pentoses. Effect of Varying Proportions of Components of Bial's Color Reagent

Comprehensive Monosaccharide Composition Analysis of Insoluble Polysaccharides by Permethylation To Produce Methyl Alditol Derivatives for Gas Chromatography/Mass Spectrometry

Knowledge of the monosaccharide composition of plant and microbial cell wall polysaccharides is critical for the understanding of polysaccharide structure and function. Differences in the hydrolytic stability of the glycosidic bonds and in the susceptibility of monosaccharides to acid-catalyzed degradation cause inconsistency of signal response in the common glycosyl composition methods. In addition, many polysaccharides are insoluble, partially soluble, or form highly viscous gels in water, and this also hinders or even prevents detection by traditional methods. As a result, currently available methods for monosaccharide composition analysis lack accuracy and are limited to the soluble portions of biological samples or expose the polysaccharides to very harsh conditions, resulting in loss of less stable residues. Here we present a new approach to accomplish the monosaccharide composition analysis of polysaccharides, including those that are not or sparingly soluble, based on permethylation in DMSO as the initial derivatization step. Our key finding is that the permethylation solubilizes the polysaccharide before the hydrolysis step, so that differences in solubility are no longer a factor in the efficiency of the acid-catalyzed depolymerization. After the hydrolysis, the partially methylated monosaccharides are reduced to alditols and remethylated for GC/MS analysis. In addition to enabling composition analysis of insoluble polysaccharides, this method also has the advantages that it is comprehensive, allowing quantification of all types of sugars, including uronic acids, on the same column and gives consistent response factors for different monosaccharide classes.

Enzymatic diversity of the Clostridium thermocellum cellulosome is crucial for the degradation of crystalline cellulose and plant biomass

The cellulosome is a supramolecular multienzyme complex comprised of a wide variety of polysaccharide-degrading enzymes and scaffold proteins. The cellulosomal enzymes that bind to the scaffold proteins synergistically degrade crystalline cellulose. Here, we report in vitro reconstitution of the Clostridium thermocellum cellulosome from 40 cellulosomal components and the full-length scaffoldin protein that binds to nine enzyme molecules. These components were each synthesized using a wheat germ cell-free protein synthesis system and purified. Cellulosome complexes were reconstituted from 3, 12, 30, and 40 components based on their contents in the native cellulosome. The activity of the enzyme-saturated complex indicated that greater enzymatic variety generated more synergy for the degradation of crystalline cellulose and delignified rice straw. Surprisingly, a less complete enzyme complex displaying fewer than nine enzyme molecules was more efficient for the degradation of delignified rice straw than the enzyme-saturated complex, despite the fact that the enzyme-saturated complex exhibited maximum synergy for the degradation of crystalline cellulose. These results suggest that greater enzymatic diversity of the cellulosome is crucial for the degradation of crystalline cellulose and plant biomass, and that efficient degradation of different substrates by the cellulosome requires not only a different enzymatic composition, but also different cellulosome structures.

Grafting of aminated oligogalacturonans onto Douglas fir barks. A new route for the enhancement of their lead (II) binding capacities

Chemical modification of Douglas fir bark and its subsequent utilization in adsorption of PbII from aqueous solutions was investigated. A new approach to enhance the natural properties of bark by covalent grafting of oligogalacturonans was developed. The polysaccharidic moiety of barks was functionalized by periodate oxidation and derivatized after reductive amination in presence of aminated oligogalacturonic acid. PbII adsorption isotherms of derivatized barks were then determined and compared with the capabilities of crude barks using the Langmuir adsorption model in terms of affinity (b) and maximum binding capacities (q(max)). Derivatization resulted in significant enhancements of the q(max) values (up to x8), along with little change of the affinity parameter.

Nalidixic Acid and the Metabolism of Escherichia coli

Nalidixic acid (NAL) is bactericidal for E. coli B. Synthesis of deoxyribonucleic acid (DNA), ribonucleic acid and protein was necessary to initiate the lethal effect, but only protein synthesis was necessary to sustain it. NAL inhibited DNA synthesis specifically, but this inhibition occurred even under conditions that were not lethal to the bacteria. In contrast to other inhibitors of DNA synthesis, NAL did not cause the solubilization of cellular DNA even when bacteria were exposed to it for 2 hr. A bacterial mutant deficient in DNA polymerase was much more sensitive to the lethal action of NAL than its parent strain. Moreover, inhibition of protein synthesis did not protect this mutant from NAL-induced killing. NAL inhibited neither DNA polymerase, nor thymidine or thymidylate kinases. The data are interpretated as suggesting that NAL altered the structure of DNA or a protein attached to nascent DNA and that this lesion can be partially repaired by DNA polymerase.

Severe Gestational Hypothyroidism Increases BBB Nutrient Transport in the Offspring

Brain growth spurt and development is highly influenced by thyroid hormones. We reported earlier that chronic maternal potassium thiocyanate feeding (induced moderate hypothyroidism) resulted in reversible decrease in Blood-Brain Barrier (BBB) glucose transport in the offspring. To assess whether severe hypothyroidism as often seen in endemic areas would have greater effect, we have now determined the thyroid status and BBB nutrient transport in the pups born to dams made severely hypothyroid by feeding 6-n-propyl thiouracil (PTU), the potent antithyroid compound. The pups of PTU fed dams had lower birth weights (P < 0.001) than controls. Their weanling body weight and brain weight were also significantly lower. They were very severely hypothyroid (serum T4 < 0.7 μg/d1 and T3 < 0.5 ng/ml) and surprisingly there was a significant increase in the BBB transport of all three nutrients tested (leucine, tyrosine and 2-deoxy-D-glucose). The increased BBB nutrient transport however does not appear to be due to opening/breakdown of BBB as evident from the lack of extravasation of Evans blue injected into the carotid artery. Interestingly, T3 supplementation to the dams and offspring, could mitigate the changes not only in BBB nutrient transport but also their body and brain weights at weanling.

Agarose-carrageenan hybrid polysaccharides from Lomentaria catenata

Two polysaccharide fractions, PS1 and PS2 from Lomentaria catenata consisted of D-Gal, L-Gal, D-Glc, D-Xyl, D-GlcA and sulphate. Partial hydrolysis led to the isolation and identification of oligosaccharides indicating the co-existence of an agarose and carrageenan backbone structure, in which D-Glc and D-GlcA residues occur as single units branching at O-3 of -->4)alpha-D-Gal(1--> and O-4 of -->3)beta-D-Gal(1-->, respectively.

A modified orcinol test for the specific determination of RNA

The standard orcinol test for estimating RNA is modified and developed as a specific method for the determination of RNA in the presence of DNA and proteins. The main differences in the procedure of the modified test when compared to that of the standard test are preincubation of the samples with H2SO4 before addition of the orcinol reagent, decreased concentration of orcinol, no addition of FeCl3.6H2O, and quantitation of RNA at its maximum absorbance under these conditions at 500 nm where interferences from DNA and proteins were minimal.

Polyamine metabolism in enucleated mouse L-cells

The distribution of polyamines between the nucleus and the cytoplasm, and the role of the nucleus in polyamine metabolism, have been studied using cells enucleated with cytochalasin B. Spermidine and spermine were found in the nuclear and the cytoplasmic fractions of L929 cells; their concentration was 3-fold higher in the former fraction. Ornithine decarboxylase activity was only found in the cytoplasm, and this activity could be stimulated in enucleated cells by the addition of fresh medium. These cells synthesized putrescine actively, but the putrescine made was not converted to spermidine, and accumulated to relatively high concentrations. Similarly, methionine did not act as a precursor to spermidine in enucleated cells, in contrast to whole cells, although it was incorporated into cell protein. Spermidine synthesis, unlike putrescine synthesis, appears to be completely dependent on a nuclear component.

Changes in rat parotid salivary proteins induced by chronic isoproterenol administration

Changes in the rat parotid gland and its secretion, brought about by chronic isoproterenol administration, were studied. In addition to the expected enlargement, morphological and biochemical analyses of the glands showed evidence of changes in the secretory components. Chromatographic and electrophoretic experiments revealed both qualitative and quantitative changes in the secretory proteins.

T6r+-induced proteins and nucleic acids in Escherichia coli infected in the presence of streptomycin

Streptomycin does not strongly inhibit T-even phage multiplication in the streptomycin-susceptible polyauxotroph, Escherichia coli strain T(-)H(-)U(-). The relatively slight inhibition, observed earlier, on production of late proteins has now been studied further. The phage-induced ribonucleic acid, synthesized in T6 phage infection in the presence of streptomycin, has been characterized by its base composition, size distribution, and behavior in hybridization tests. Comparison of these properties to those of control samples, taken during either early or late periods of infection, have not shown any significant differences. Phage-induced proteins, synthesized at different times during infection, were studied by disc-gel electrophoresis. Staining and autoradiography of the patterns of pulse-labeled proteins, formed in the absence and presence of the antibiotic showed only slight quantitative changes in the appearance of early proteins. More marked quantitative effects were detected later in infection. Nevertheless, changes in the mobilities of the different proteins were not observed in the streptomycin-treated cultures at any time after infection, suggesting the absence of gross misreading sufficiently great to alter the distinctive electrophoretic patterns of the extracts. Cells infected and incubated in the presence of the antibiotic were found to contain intact virus particles, as shown by electron microscopy. Such infected cells contained extensive deoxyribonucleic acid pools and did not develop the rounded nucleoids with enclosed dense bodies characteristic of the lethal action of the antibiotic. On the other hand, infected bacteria previously exposed to lethal concentrations of streptomycin were unable to synthesize the early enzymes, deoxycytidylate (dCMP) hydroxymethylase and dihydrofolate reductase, or to make phage deoxyribonucleic acid and phage. Such previously killed cells contained the rounded and clotted nucleoids and were unable to unravel this pathological structure after phage infection.

A non-nucleotide polymer found in the DNA of the sand dollar, Echinarachnius parma. II. Preliminary characterization

A preliminary characterization of the non-nucleotidic component present in the DNA of Echinarachnius parma was undertaken. This material has an extremely high sedimentation coefficient (907 S). It contains no deoxyribose and presumably no ribose. After acid hydrolysis it was strongly ninhydrin-positive and also gave positive tests for reducing sugars as well as a slightly positive test for amino sugars. Upon electrophoretic analysis of an acid hydrolysate, three ninhydrinpositive spots were detected. One of these migrated to the negative electrode with a mobility identical with that of galactosamine, the other migrated to the positive electrode, and the third was neutral at pH 6.3. The spot with a mobility identical with that of galactosamine also gave a positive test for amino sugar. The material was not attacked by α-amylase. However, digestion with a crude trypsin preparation resulted in loss of the banding property in gradients of cesium chloride. Exposure to purified trypsin did not completely digest it, but caused an increase in buoyant density.

EFFECT OF OZONE ON SURVIVAL AND PERMEABILITY OF ESCHERICHIA COLI

Scott, D. B. McNair (University of Pennsylvania, Philadelphia) and E. C. Lesher . Effect of ozone on survival and permeability of Escherichia coli . J. Bacteriol. 85: 567–576. 1963.— Escherichia coli cultures in the logarithmic phase or resting were treated with various concentrations of ozone in saline solution. Approximately 2 × 10 7 molecules of ozone per bacterium killed 50% of the cells. Ozone caused leakage of cell content into the medium, and lysis of some cells. Low concentrations of ozone did not react with the glutathione within the cells, although reaction with glutathione in solution was immediate and stoichiometric. The effect on nucleic acid within the cells was to change the solubility and to cause the release of ultraviolet-absorbing material into the medium. Ozone attacked the ring structure of the base or the carbohydrate only when the substance was in the medium. Nucleic acids released into the medium were reabsorbed by cells which were not lysed. Viable cells resumed growth immediately, and grew at rates determined by the nutrients either added to the medium or which resulted from leakage and lysis of nonviable cells. It is postulated that the primary attack of ozone was on the cell wall or membrane of the bacteria, probably by reaction with the double bonds of lipids, and that leakage or lysis of the cells depended on the extent of that reaction.