Decrease In Polysaccharide Content Research Articles

The response mechanism of alkalophilic Nitzschia sp. NW129 to low alkalinity-A study combining physiological and transcriptional analysis

Global aquatic acidification significantly threatens alkaline lake ecosystems. The mechanisms by which alkaliphilic microalgae, the key producers in these ecosystems, respond to reduced environmental alkalinity remain poorly understood. Here, we investigated the responses of alkalophilic Nitzschia sp. NW129 to low alkalinity (pH 9.2) through integrated physiological-biochemical and transcriptomic analyses. Relative to the control (pH 11.5), we observed a 60.1 % decrease in polysaccharide content, while total lipids and proteins increased by 1.74-fold and 2-fold, respectively. Transcriptome analysis revealed up-regulation of genes encoding carbonic anhydrase (CA) and malic enzyme (ME), along with those involved in glycolysis and fatty acid (FA) synthesis, compensating for carbon supply and shifting carbon flux from carbohydrate synthesis to lipid accumulation. Enhanced expression of TCA cycle genes and those encoding F-ATP synthase and inorganic pyrophosphatase (PPase) provided sufficient energy for cellular homeostasis, further facilitated by the up-regulated expression of ATP-dependent V-ATPase and ABC transporter genes. Temporal analysis revealed that the expression of genes involved in protein synthesis pathways was up-regulated on days 1 and 4 but notably down-regulated on day 2, suggesting protein degradation at this time to balance energy supply for adaptation. Despite these coping shifts, impairments in photosynthetic energy dissipation and electron transport, along with transcriptional changes including down-regulating cell cycle and inducing apoptotic pathways, ultimately caused a substantial reduction in biomass. These findings provide a basic understanding of the response mechanisms of alkalophilic microalgae to low alkalinity stress, which should aid to develop strategies to improve microalgal tolerance against acidification.

Study on the components changes of polysaccharides and saponins during nine steaming and drying of Polygonatum sibiricum.

In this study, the content and structure of Polygonatum sibiricum polysaccharides and saponins during different processing stages were determined. After processing of Polygonatum, the content of polysaccharide and glucose decreased, and the content of galactose, glucuronic acid and sugar substitution gradually increased. The content of total saponins increased significantly. Only 18 compounds were found in raw Polygonatum and 17 new compounds were presented in processed Polygonatum. During the processing of Polygonatum, the polysaccharide was partially degraded into oligosaccharides, the molecular weight gradually decreased, and the neutral sugar was converted into uronic acid, resulting in a decrease in polysaccharide content. The saponins were partially degraded into sapogenins or modified. This study clarifies the changes in the content and structure of polysaccharides and saponins in processed Polygonatum, which will pave the way for elucidating the processing mechanism. © 2024 Society of Chemical Industry.

Effects of pretreatment methods on the physicochemical properties of dried longan (Dimocarpus longan Lour.) pulps.

Several pretreatment methods were used before hot air drying to determine the effects of pretreatment on the physicochemical properties of dried longan pulps to address issues of low efficiency and excessive browning of pulps in dried longan. The results showed that pretreatment methods such as sodium chloride steeping, hot blanching, and freeze-thawing reduced the moisture content in dried longan pulps and increased the hardness of dried longan pulps. Ultrasound, microwave, and hot blanching methods reduced the degree of browning of dried longan pulps. Freeze thawing led to a decrease in polysaccharide content in dried longan pulps. The use of ultrasound- and microwave-based pretreatment methods increased the contents of free phenolics and total phenolics and increased the oxygen radical absorbance capacity indices. Alkenes and alcohols constituted the primary volatile flavor substances in longan. It was inferred that it was favorable to use the hot blanching method before subjecting the samples to conditions of hot air drying as the moisture content and degree of browning could be reduced effectively. The results reported herein can potentially help manufacturers improve drying efficiency. The results provide a platform to produce high-quality products from dried longan pulps. PRACTICAL APPLICATION: Longan pulps should be subjected to conditions of the hot blanching method before subjecting the samples to conditions of hot air drying to reduce the moisture content and degree of browning. The results reported herein can help manufacturers improve the drying efficiency of pulps. The results can be exploited to produce high-quality products from dried longan pulps.

Dynamics of non-structural carbohydrates in Pinus pallasiana D. Don needles under different forest growth conditions of ravine anti-erosion plantations

Abstract The research was aimed at analysing the peculiarities of non-structural carbohydrate metabolism in the needles of Pinus pallasiana D. Don in anti-erosion plantations on the slope and in the thalweg of the Viyskovyi ravine under different forest growth conditions. The ravine is located in the Dnipropetrovsk region and belongs to the southern geographical variant of ravine forests. The studied plants grew at three experimental sites of man-made plantation: in the thalweg (forest growth conditions – mesophilic, fresh, CL2), in the middle part of the slope of the southern exposure (mesoxerophilic, somewhat dry, or semi-arid, CL1) and on the upper part of this slope (xerophilic, arid, CL0–1). Changes in glucose, fructose, reducing sugars, sucrose and starch during the period from May to October were studied. The concentration of osmotically active substances (glucose, sucrose) increases in the months with the most unfavourable hydrothermal parameters, especially in plants of mesoxerophilic and xerophilic forest growth conditions. The dynamics of fructose content revealed two maxima (July and October), when the concentration of glucose tends to increase steadily, with the highest values found in October. During the study period, the level of fructose in the needles under the arid conditions of the upper and middle parts of the slope was much lower than under the fresh conditions of the thalweg. The dynamics curve of the starch content tends to decrease from the maximum values in May to the first minimum in August. It is followed by some increase in the concentration of this polysaccharide that does not reach the previous values. The second minimum is registered in October. Such changes in the level of starch in the needles of plants are observed under all forest growth conditions. The decrease in polysaccharide content is consistent with the increase in glucose and sucrose, especially in August. A more significant increase in the concentration of soluble osmoprotective sugars (glucose, sucrose) in P. pallasiana needles under unfavourable hydrothermal conditions compared to normal moisture conditions indicates the ability of plants to adapt to mesoxerophilic and xerophilic conditions.

Effect of active modified atmosphere packaging with different initial gas compositions on nutritional compounds of shiitake mushrooms (Lentinus edodes)

The effect of active modified atmosphere packaging with different initial gas compositions on fresh shiitake mushrooms was investigated. Shiitake mushrooms were packaged under each of the following conditions: (1) high oxygen packaging (HOP), 100% oxygen initially; (2) medium oxygen packaging (MOP), 50% O2 and balanced with N2 initially; (3) low oxygen packaging (LOP), 3% O2/5% CO2, balanced with N2 initially. Passive modified atmosphere packaging with air inside initially (AIR) was used as the control treatment. All the packaged samples were stored at 10°C with 90% RH for 7 days. During storage, gas compositions, electrolyte leakage, crude water-soluble polysaccharides, total phenolic content and free amino acid content were determined. The results showed that ethanol release was high in LOP and AIR but retarded in MOP and HOP. No packaging could prevent the decrease in polysaccharide content decreasing. Both the active and passive modified atmosphere packaging maintained the color and integrity of the mushrooms. The active modified atmosphere packaging had a significant effect on the increase of total phenolic content and total amount of free amino acids. LOP had a harmful impact on mushrooms with high levels of electrolyte leakage. In conclusion, HOP and MOP had a better effect on maintaining the nutritional compounds of shiitake mushrooms.

Decomposition in soil and chemical changes of maize roots with genetic variations affecting cell wall quality

SummaryRoots of brown‐midrib (F2bm1 and F292bm3) maize mutants and their normal isogenic counterparts (F2 and F292) were used to evaluate the changes in chemical cell wall features with regard to polysaccharides, lignin composition and interconnecting phenolic acids during root degradation in soil. To this end, the chemical variability of roots of brown‐midrib mutants and their normal counterparts was compared and its subsequent impact on carbon (C) mineralization determined under controlled conditions. The bm1 mutation mainly caused an increase in lignin content and a decrease in polysaccharide content of maize roots whereas the bm3 mutation caused only a decrease in polysaccharide content. The lignin composition of bm roots differed from that of normal lines and the proportion of cell wall ester‐linked hydroxycinnamic acids was also different. C mineralization kinetics differed markedly between the genotypes. Certain relevant factors concerning root decomposition in soil were studied from the relationships between the chemical characteristics of maize roots at different stages of decomposition and C mineralization rates. The Klason lignin‐to‐glucose ratio (KL/Glu), the Klason lignin‐to‐arabinoxylans ratio (KL/AX) and the arabinose‐to‐xylose ratio (A/X) were proposed as promising predictive indicators of C mineralization kinetics. Future estimations of soil residue decomposition could be improved by taking these initial chemical criteria into account on a wider range of residues. Décomposition dans le sol et évolution de la qualité chimique des racines de maïs présentant des modifications génétiques de la qualité des parois cellulaires’ Résumé Les racines des maïs mutants brown‐midrib (F2bm1 et F292bm3) et celles de leurs lignées isogéniques normales (F2 et F292) ont été utilisées pour évaluer les modifications des caractéristiques chimiques des parois cellulaires, à travers la composition des polysaccharides, de la lignine et la nature des acides phénoliques, au cours de la dégradation des racines dans le sol. Pour cela, nous avons examiné, en conditions contrôlées, l’impact d’une variabilité de la qualité chimique des racines, en comparant les mutants bm et leurs lignées isogéniques normales, sur la minéralisation du C. La mutation bm1 engendre principalement une augmentation de la teneur en lignine et une diminution de la teneur en polysaccharides dans les racines de maïs alors que la mutation bm3 cause uniquement une diminution de la teneur en polysaccharides. Dans les racines des mutants bm, la composition de la lignine ainsi que les proportions en acides hydroxycinnamiques estérifiés des parois cellulaires diffèrent de celles des lignées non mutantes. Les cinétiques de minéralisation du C varient fortement entre les génotypes. Les relations entre les caractéristiques chimiques des racines de maïs à différents stades de décomposition et les taux de minéralisation du C ont permis d’étudier certains facteurs pertinents concernant la décomposition des racines dans le sol. Les rapports lignine Klason sur glucose (KL/Glu), lignine Klason sur arabinoxylanes (KL/AX) et arabinose sur xylose (A/X) ont été identifiés comme étant de bons indicateurs de prédiction des cinétiques de minéralisation du C. La prise en compte de ces critères de qualité chimique initiale sur une plus large gamme de résidus pourrait améliorer l’estimation de la décomposition des résidus dans le sol.

Bark decay by the white-rot fungus Lentinula edodes: Polysaccharide loss, lignin resistance and the unmasking of suberin

Abstract The chemical composition of oak bark during growth of Lentinula edodes was studied to assess the transformation of lignin, suberin, tannin and structural polysaccharides. Oak logs (Quercus alba) were decayed by L. edodes over 8 years, during which time they were sampled at five intervals (30, 40, 66, 77, 101 months). Elemental analysis (C, H, N and O), solid-state 13C NMR as well as off-line thermochemolysis in the presence of tetramethylammonium hydroxide (TMAH) with gas chromatography-mass spectrometry were used in the characterization of fresh and degraded barks. Solid-state 13C NMR analysis showed that cellulose and xylans were the main structural components of fresh bark but that L. edodes caused a 46% decrease in polysaccharide content and that loss of crystalline and non-crystalline cellulose regions occurred in parallel. The decrease in cellulose content was accompanied by a relative increase in the proportion of methylene carbon from suberin. The aromatic region of the spectra revealed a loss of a shoulder at 145 ppm attributed to tannins after 30 months decay; in contrast the aromatic content remained unaltered, suggesting that highly structured tannins were degraded in preference to lignin. Chemolytic treatment with TMAH confirmed moderate changes in guaiacyl and syringyl acid-aldehyde ratios with growth indicating that the fungus had not caused extensive oxidative side chain alterations. The ratio of syringyl to guaiacyl units ( S / G ) in fresh oak bark was lower at ∼0.6 than that previously reported for oak sapwood ( S / G > 1 ) and a slight decrease in S / G values was observed with fungal decay. The resistance of bark lignin as compared to sapwood lignin is attributed in part to the inhibiting effect of tannins and suberin on fungal growth.

Effect of a salt‐osmotic upshock on the edaphic microalga Neochloris oleoabundans

Abstract. The edaphic microalga Neochloris oleoabundans (isolated from desert soil) was subjected to a salt‐osmotic shock from 0 to 0·6 kmol m−3 NaCl. The effect of the osmotic upshock on the cell composition was determined. The cell dry weight and the lipid, glycerol and soluble amino acids contents remained unchanged during 5d of osmotic upshock. The protein content increased after 2d of initial osmotic shock, and it appears to be a long‐term haloadaptation process of the cells. The most important short‐term effects of salt osmotic upshock were a decrease in polysaccharide content and an increase in the soluble carbohydrate content of Neochloris oleoabundans cells. Within the first 4h after the initial shock, there was a transfer of carbon units from polysaccharides to sucrose which was independent of photosynthesis. The increase of intracellular concentration of sucrose contributed to cell osmoregulation.

Buoyancy regulation in phosphate-limited cultures ofMicrocystis aeruginosa

Buoyancy regulation was studied in P-limited continuous cultures of Microcystis aeruginosa grown on light-dark cycles of 8–16 h. Gas-vesicle content did not vary systematically over a range of dilution rates form 0.004 to 0.015 h−1. A reduction in irradiance did not cause a significant change in gas-vesicle content. The proportion of floating cells decreased during the photoperiod and increased during the dark period. At three dilution rates, parallel cultures were grown at growth-saturating irradiance and at a lower irradiance. The cultures at low irradiance had a higher proportion of floating cells and a smaller decrease in buoyancy during the light period. The buoyancy losses were not due to destruction of gas vesicles but, rather, to the accumulation of heavy substances. However, measured increases in polysaccharide ballast accounted for only 60% of the required ballast. The molecule(s) which comprised the remainder of the ballast are unknown. Upon relief of phosphate limitation, P-limited cultures increased their buoyancy when incubated in the dark or light. Buoyancy increases in the dark were correlated with a decrease in polysaccharide content, whereas there was an increase in gas vesicle content in the light.

Effect of periodate oxidation on the polysaccharide content and microaggregate stability of rhizosphere and non-rhizosphere soils

The relationship between the stability of soil microaggregates in water and the polysaccharide content was examined in rhizosphere and non-rhizosphere samples from a pot experiment using three soils that had grown peas, barley or grasses. The polysaccharide was oxidised and removed using 168h treatment with 0.02M periodate followed by 6h with 0.1M tetraborate. The decrease in polysaccharide content, measured as change in residual reducing sugars, was compared with the stability of soil microaggregates (ca 45μm) in water, determined by a turbidimetric method.

Contribution to the Development of Clinical Application of Polarographic Protein Wave

Polarographic behaviour of filtrate substance can be attributed to serum mucoprotein, which is mainly contained in α-globulin and exists as either free or combined form; the latter is transformed into the former by the procedure of serum denaturation. In opposite to the cancer diseases, in most cases of liver parenchym-damages the content of serum mucoproteins decreases below the normal value, showing the loss in vital reactivity. From the experimental data, the present author assumes that the mucoprotein can be reproduced in the liver cells and participate in the course of reparatory process.Although the physiological role of mucoprotein remains yet unknown, we have found that the serum mucoprotein is the essential factor affecting the mechanism of clinical tests, such as heat-coagulation serum tests, for example, Weltmann method or cobaltritests, while the urinal mucoprotein is the essental factor of Donaggio test. Comparing the chemical and polarographic methods of investigating mucoprotein, it has become clear that both results show a parallelism and the serum mucoproteins have heterogeneous structure with respect to the SH or S-S groups, or to the polysaccharide protein. From the experiments with the isolated serum protein fractions, it has become evident that the wave height in the polarographic digest test depends mainly on the ratio of the contents of serum globulin and albumin in the serum. The paper electrophoretic technique in combination with polarographic protein test, proposed by Homolka, is an excellent method for finding the qualitative changes of protein fractions in the case of various diseases. Concerning the significance of double wave, the assumption made by Balle-Helaers, that the first wave represents the polysaccharide and the second the SH or S-S group of protein molecule, agrees well with our observation that the decrease in first wave by the denaturation is always accompanied by the decrease in polysaccharide content.