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Origin of defects in assembled supramolecular structures of sweet potato starches with different amylopectin chain-length distribution

A combined approach of fluorophore-assisted capillary electrophoresis (FACEL), high-sensitivity differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and light (LM) and scanning electron microscopy (SEM) was applied to study the effects of changes in amylopectin chain-length distribution on the assembly structures of sweet potato starches with similar amylose levels. It was shown that unlike ordinary sweet potato starch, starch extracted from Quick Sweet cultivar of sweet potato had anomalous high level of amylopectin chains with a degree of polymerization (DP) 6–12. Joint analysis of the obtained data revealed that amylopectin chains with DP 10–24 are, apparently, the dominant material for the formation of supramolecular structures in starch granules. In contrast, amylopectin chains with DP < 10 facilitated the formation of defects within crystalline lamellae. An increase in relative content of amylopectin chains with DP < 10 is accompanied by the correlated structural alterations manifested at all levels of starch granule organization (crystalline lamellae, amylopectin clusters, semi-crystalline growth rings, and granule morphology). Thus, the short amylopectin chains with DP < 10 were considered as an origin of the defectiveness in starch supramolecular structures.

Influence of sulfidation treatment on the structure and tribological properties of nitrogen-doped diamond-like carbon films

The nitrogen-doped diamond-like carbon (DLC) films were deposited on high speed steel (HSS) substrates in the direct current unbalanced magnetron sputtering system. Sulphurized layer was formed on the surface of DLC films by means of liquid sulfidation in the intermixture of urea and thiourea solution in order to improve the tribological properties of DLC films. The influence of sulfidation treatment on the structure and tribological properties of DLC films was investigated in this work. The structure and wear surface morphology of DLC films were analyzed by Raman spectroscopy, XPS and SEM, respectively. It reveals that the treated films are smooth and uniform; and sulfur atoms are bonded chemically. The treated films have broader distribution of Raman spectra in the range of 1000–1800 cm −1 and higher I D/ I G ratio than the untreated films as a result of the appearance of the crystalline graphite structure after the sulfidation treatment. It is showed that the sp 2 relative content increase in the treated films from the XPS measurement. The Raman results are consistent with the XPS results. The tribological properties of DLC films were investigated using a ball-on-disk rotating friction and wear tester under dry friction conditions. It is found that the sulfidation concentration plays an important part in the tribological properties of the treated DLC films. The results showed the treated films with low sulfidation concentration have a lower friction coefficient (0.1) than the treated films with high sulfidation concentration (0.26) and the untreated films (0.27) under the same friction testing conditions, which can be attributed to both the presence of sulfur-containing materials and the forming of the mechanical alloyed layer on the wear surface. Adding the dry nitrogen to the sliding surface in the testing system helps the friction coefficient of the treated films with low sulfidation concentration to decrease to 0.04 further in this work. On the basis of the experimental results, it is indicated that the liquid sulfidation technique, which is low-cost, non-polluting and convenience, would be an appropriate method for the surface treatment of DLC films.

Amplification of 1-deoxy-d-xyluose 5-phosphate (DXP) synthase level increases coenzyme Q10 production in recombinant Escherichia coli

For the enhancement of coenzyme Q(10) (CoQ(10)) production, 1-deoxy-D-xylulose 5-phosphate (DXP) synthase of Pseudomonas aeruginosa was constitutively coexpressed in a recombinant Escherichia coli strain, which harbors the ddsA gene from Gluconobacter suboxydans encoding decaprenyl diphosphate synthase. It was found that the expression of the ddsA gene caused depletion of the isopentenyl diphosphate (IPP) pool in E. coli. Amplification of DXP synthase level by installing P. aeruginosa DXP synthase restored the diminished IPP pool and concomitantly resulted in approximately a twofold increase in relative content and productivity of CoQ(10). Maximum CoQ(10) concentration of 46.1 mg l(-1) was achieved from glucose-limited fed-batch cultivation of the recombinant E. coli strain simultaneously harboring the ddsA and dxs genes.

Carbohydrate accumulation in Siberian spruce needles of various ages

The content of mono- and oligosaccharides, hemicelluloses, and water-soluble polysaccharides was studied in Siberian spruce (Picea obovata Ledeb.) needles of various ages. Accumulation of carbohydrates during the growth period and the ratio of their individual fractions were determined by the proportions between the growth rate and assimilate export in developing needles. Throughout the growth period, the content of monosaccharides in needles of all ages was much higher than that of oligosaccharides. Unlike the period of active growth, the dormancy period was characterized by a wider diversity of oligosaccharides and their rather high content. Hemicelluloses that accumulated during the previous growth season and water-soluble polysaccharides of 2- and 3-year-old needles were involved into metabolism at the time of active growth of current-year needles. Analysis of carbohydrate accumulation in 1- to 9-year-old needles showed that the monosaccharide concentration was higher in needles of the first two years. The content of hemicelluloses A and B and water-soluble polysaccharides was higher in older needles. During the growth period, the assimilates of 2- and 3-year-old needles were partly used for the formation of young needles. The increase in relative content of polysaccharides during needle senescence reflects the involvement of photosynthetic products into the secondary pool of carbon metabolites.

Study of Ag/La0.6Sr0.4MnO3 catalysts for complete oxidation of methanol and ethanol at low concentrations

Ag-modified La0.6Sr0.4MnO3-based catalysts with the perovskite-type structure were prepared by using a citric acid sol–gel method, and their catalytic performance for complete oxidation of methanol and ethanol was evaluated and compared with that of the γ-Al2O3-supported catalysts, Ag/γ-Al2O3, Pt/γ-Al2O3, and Pd/γ-Al2O3. The results showed that the Ag-modified La0.6Sr0.4MnO3-based catalysts with the perovskite-type structure displayed the activity significantly higher than that of the supported precious metal catalysts, 0.1%Pd/γ-Al2O3 and 0.1%Pt/γ-Al2O3 in the temperature range of 370–573K. Over a 6%Ag/20%La0.6Sr0.4MnO3/γ-Al2O3 catalyst, the T95 temperature for methanol oxidation can be as low as 413K. Even at such low reaction temperature, there were little HCHO and CO detected in the reaction exit-gas. However, for the 0.1%Pd/γ-Al2O3 and 0.1%Pt/γ-Al2O3 catalysts, the HCHO content in the reaction exit-gas reached ∼200 and ∼630ppm at their T95 temperatures. Over a 6%Ag/La0.6Sr0.4MnO3 catalyst, the T95 temperature for ethanol oxidation can be as low as 453K, with a corresponding content of CH3CHO in the exit-gas at 782ppm; when ethanol oxidation is performed at 493K, the content of acetaldehyde in the exit-gas can be below 1ppm. Characterization of the catalysts by X-ray diffraction (XRD), TEM, XPS, laser Raman spectra (LRS), hydrogen temperature-programmed reduction (H2-TPR) and oxygen temperature-programmed desorption (O2-TPD) methods revealed that both the surface and the bulk phase of the perovskite La0.6Sr0.4MnO3 played important roles in the catalytic oxidation of the alcohols, and that γ-Al2O3 as the bottom carrier could be beneficial in creating a large surface area of catalyst. Moreover, a small amount of Ag+ doped onto the surface of La0.6Sr0.4MnO3 was able to partially occupy the positions of La3+ and Sr2+ due to their similar ionic radii, and thus, became stabilized by the perovskite lattice, which would be in favor of preventing the aggregation of the Ag species on the surface and enhancing the stability of the catalyst. On the other hand, modification of the Ag+ to the surface of La0.6Sr0.4MnO3 resulted in an increase in relative content of the surface O22−/O− species highly reactive toward the alcohols and aldehydes as well as CO. Besides, solution of low-valence metal oxides SrO and Ag2O with proper amounts in the lattice of the trivalent metal perovskite-type oxide LaMnO3 would also lead to an increase in the content of the reducible Mnn+ and the formation of anionic vacancies, which would be favorable for the adsorption-activation of oxygen on the functioning catalyst and the transport of the lattice and surface oxygen species. All these factors would contribute to the pronounced improvement of the catalyst performance.

Expression of the glutamate transporters in human temporal lobe epilepsy

Glutamate is the major excitatory neurotransmitter in the central nervous system and is implicated in the pathogenesis of neurodegenerative diseases. Five human glutamate transporters have been cloned and are responsible for the removal of potentially excitotoxic excess glutamate from the extracellular space. In this study we consider whether there are selective changes in the expression of the glutamate transporters in the medial temporal cortex and hippocampus from temporal lobe epilepsy patients, which might contribute to the development or maintenance of seizures. Since disruption of the glial transporter excitatory amino acid transporter 2 in mice results in lethal spontaneous seizures, we were interested primarily in studying changes in this transporter. Using in situ hybridization we show that there was no reduction in the level of excitatory amino acid transporter 2 encoding messenger RNA in the temporal lobe epilepsy cases compared to post mortem controls and indeed there was a relative increase in content of excitatory amino acid transporter 2 messenger RNA per cell in temporal lobe epilepsy cases. Western blotting showed that there was no change in the excitatory amino acid transporter 2 protein content in temporal lobe epilepsy cases as compared to post mortem controls. A small reduction in the level of the second astroglial transporter protein, excitatory amino acid transporter 1, was observed in temporal lobe epilepsy cases. Surprisingly, immunohistochemical experiments using a polyclonal anti-excitatory amino acid transporter 2 antibody, showed a different localization of this protein in epilepsy derived tissue as compared to post mortem controls although glial markers such as glial fibrillary acidic protein and glutamine synthase showed similar patterns of staining. However, repeating this experiment using control tissue from non temporal lobe epilepsy biopsies demonstrated that this change in the excitatory amino acid transporter 2 transporter localization occurred post mortem. These data suggest that major changes in the level of expression of the glutamate transporters do not play an important role in the development of human temporal lobe epilepsy but may be implicated the aetiology of other types of epilepsy.

Effect of Porcine Somatotropin (pST) on Body Composition, Meat Quality and Characteristics of Backfat in Genetically Different Pigs

AbstractThe influence of genotype, pST and stress reactivity on carcass composition, meat and fat quality was investigated in 57 growingfinishing pigs. Pietrain pigs contained more meat and less fat in carcass in comparison to Schwerfurter breed. Exogenous pST improved the carcass composition with regard to leaness. The inhibitory effect of pST on fat synthesis caused a reduced chemical fat in adipose tissue, reduced size and number of fat cells and an increase of relative content of polyunsaturated fatty acids. Halothane reactivity mainly influenced the composition of carcass. Stress‐positive pigs were leaner than H'pigs. The factors pST, breed and halothane reactivity slightly affected the meat quality.

Mössbauer and x-ray investigations of oxidized ultrafine iron particles treated with high-pressure and electrodischarge pulses

Ultrafine iron particles with an average size of 30 nm were obtained by the levitation method in an inert gas flow. Electrodischarge experiments were carried out under a pressure of 3 GPa. The values of the parameters of electrodischarge pulses were sufficient to move defects (ions, atoms, dislocations) by conductivity electrons to destroy the metastable state of nanocrystals, but not sufficient to generate heat wave. This effect had threshold features. After the first pulse the relative resistance drop was more than five times. Next, electrical pulses slightly reduced resistance up to its saturation. Properties of ultrafine iron particles have been studied using Mössbauer absorption spectra and x-ray diffraction for three types of samples: (a) primary powder, (b) powder treated to 3 GPa in a ‘‘toroid’’ device, (c) powder treated by electrical pulses at 3 GPa. An x-ray diffraction pattern revealed seven slightly broadened iron reflexes as well as more broadened oxide film reflexes. Oxide film reflexes correspond to the most intense reflexes of a spinel structure. The integrated intensities of 220,311 spinel reflexes divided by integrated intensity of 110 iron reflex are equal to 0.12, 0.14, and 0.19 for samples (a), (b), and (c) respectively. Thus, the relative content of oxide iron phase increases from samples (a) to (c). The increase of relative content of the oxide iron phase was confirmed by a Mössbauer absorption experiment. This effect can be explained by the transformation of the metastable solution of oxygen in iron lattice to iron oxide with a spinel structure, under the action of high-density current pulses.

Expression of four myosin heavy chain isoforms with development in mouse uterus.

In smooth muscle tissue, two or three isoforms of myosin heavy chain (MHC) have been reported (SM1, SM2, and/or NM). In mouse uterus tissue, four bands in the region of the MHC's can be resolved on high resolution SDS polyacrylamide gels. Western blots using smooth muscle (SM) MHC-specific and nonmuscle (NM) MHC-specific polyclonal antibodies show the upper two bands in the MHC region are SM isoforms, whereas the lower two bands are NM isoforms. One-dimensional peptide maps of these four bands show each to have a unique pattern of polypeptide fragments following alpha-chymotrypsin digestion. Developmental expression of myosin heavy chains (MHC) in mouse uterus, aorta, bladder, and stomach (6 ages, 10-150 days) was determined using tissue homogenates. In the uterus, both SM MHC's show an increase in relative content with increasing age, whereas the NM MHC's show a decrease. The mouse aorta shows a significant increase in the SM MHC's and a significant decrease in the NM MHC from day 10 to day 30, which is similar to data reported for the rat aorta. Whereas both the bladder and stomach contain relatively small amounts of NM MHC's (approximately 10% or less), these quantities do show decreases with development. The SM1:SM2 ratio for the uterus remains high (3.4 at 150 days) through development; the aorta, bladder, and stomach also start out high, but tend toward 1.0 in the 150-day animals. The presence of four MHC isoforms in the uterus with unique developmental regulation of expression is consistent with hypotheses of unique functional roles for these isoforms.

Comparison of soluble proteins associated with disease resistance induced by bacterial lipopolysaccharide and by viral necrosis

Infiltration of tobacco leaves with bacterial lipopolysaccharide (LPS) results in the acquisition of systemic resistance to subsequent bacterial infection. By means of gel electrophoresis, we have investigated the changes in soluble protein composition of Nicotiana tabacum cv. “Bottom Special” leaves after they were infiltrated with LPS from Pseudomonas solanacearum. A new protein band (approximate molecular weight 31800) was present in leaves infiltrated with LPS, but not in those infiltrated with phosphate buffer. In time course experiments, the accumulation of the new protein as well as the increase in relative content of at least two other proteins were correlated with the appearance of resistance to bacterial multiplication in tobacco tissues. The new protein band did not co-migrate with the “pathogenesis-related” (PR) proteins that accumulated in tobacco leaves infected with tobacco necrosis virus or tobacco mosaic virus (strain 1952-D). The PR proteins were present in tissues infiltrated with LPS as well as in extracts of tissues infiltrated with virulent and avirulent strains of P. solanaceamm, but their presence was not correlated with the acquisition of resistance to bacterial multiplication.

Content and turnover of gangliosides in rat brain following behavioural stimulation.

Abstract— Rats were placed in a tank of deep water to swim until they learned to escape (Group E) or were lifted out (Group F). Controls (Group C) were left in their home cages. Specific radioactivities of purified gangliosides, other glycolipids and nonlipid carbohydrates were measured at 9 and 24 h after intracranial injection of D‐[1‐14C]glucosamine and the subsequent swimming trials. Nonspecific effects of behavioural stimulation (similar changes in Groups E and F) included decreased net incorporation of radioactivity into monosialogangliosides and nonganglioside carbohydrates, a relative increase in content of GT1 gangliosides and decreased content of GT1 gangliosides. Specific effects (different changes in Groupe E and F) included in Group E decreased net uptake of radioactivity into disialogangliosides. These results demonstrate that in rat brain: (1) ganglioside metabolism is affected by behavioural stimulation; (2) metabolism of other heteropolysaccharides is also affected; and (3) some biochemical changes are consequences of nonspecific stimulation whereas others are associated with specific elements of experience.