Search

Chitosan (CTS)/chitosan oligosaccharide (COS) and whey protein isolate (WPI) have been frequently used as food supplements, but notably, the interaction between the carbohydrate and the protein may affect the digestibility of protein. Thus, the present study focused on effects of the interaction between CTS/COS and WPI on the protein digestibility. A series of chemical and spectroscopic techniques including gel electrophoresis, gel permeation chromatography, Fourier transform-infrared (FT-IR) spectroscopy, intrinsic fluorescence (IF) spectroscopy, and circular dichroism (CD) spectroscopy were applied. According to the findings, both CTS and COS dramatically reduced intestinal digestibility of WPI, resulting in a decrease of DH by 43.33 % and 52.31 %, respectively. The substitution degree of WPI on CTS was 0.87 g WPI/g CTS, and the electrostatic interaction between amine groups of CTS and carboxyl groups of WPI caused changes in WPI's stability, microstructure, and fluorescence intensity. Notably, CTS affected the digestibility of WPI by precipitating protein and enzyme, whereas COS altered WPI's digestibility by decreasing or inactivating enzyme activity. The present study offered a solid scientific foundation for the rational formulations of carbohydrates and proteins in food industry. [Display omitted] • Chitosan (CTS) and its oligosaccharide (COS) influenced protein digestibility. • CTS decreased protein digestibility by partially precipitating protein and protease. • COS influenced protein digestibility by decreasing the activity of protease. • The electrostatic interaction occurred between -NH 3 + of CTS and -COO− of protein. [ABSTRACT FROM AUTHOR]

Chitosan (CTS) and chitosan oligosaccharides (COS) have been widely applied in food industry due to their bioactivities and functions. However, CTS and COS with positive charges could interact with proteins, such as whey protein isolate (WPI), influencing their digestion. Interaction among CTS/COS, FUC, and WPI/enzymes was studied by spectroscopy, chromatography, and chemical methods in order to reveal the role of FUC in relieving the inhibition of protein digestibility by CTS/COS and demonstrate the action mechanisms. As shown by the results, the addition of FUC increased degree of hydrolysis (DH) and free protein in the mixture of CTS and WPI to 3.1-fold and 1.8-fold, respectively, while raise DH value and free protein in the mixture of COS and WPI to 6.7-fold and 1.2-fold, respectively. The interaction between amino, carboxyl, sulfate, and hydroxyl groups from carbohydrates and protein could be observed, and notably, FUC could interact with CTS/COS preferentially to prevent CTS/COS from combining with WPI. In addition, the addition of FUC could also relieve the combination of CTS to trypsin, increasing the fluorescence intensity and concentration of trypsin by 83.3 % and 4.8 %, respectively. Thus, the present study demonstrated that FUC could alleviate the inhibitory effect of CTS/COS on protein digestion. [Display omitted] • FUC alleviated the negative impact of CTS and COS on protein digestibility. • CTS/COS interacted with FUC preferentially and thus WPI was released. • Electrostatic interaction occurred between -NH 3 + of CTS/COS and -SO 4 2− of FUC. • FUC could hinder the combination of CTS and trypsin. [ABSTRACT FROM AUTHOR]

Background: The impacts of increasing nitrogen (N) deposition and overgrazing on terrestrial ecosystems have been continuously hot issues. Grazing exclusion, aimed at restoration of grassland ecosystem function and service, has been extensively applied, and considered a rapid and effective vegetation restoration method. However, the synthetic effects of exclosure and N deposition on plant and community characteristics have rarely been studied. Here, a 4-year field experiment of N addition and exclusion treatment had been conducted in the desert steppe dominated by Alhagi sparsifolia and Lycium ruthenicum in northwest of China, and the responses of soil characteristics, plant nutrition and plant community to the treatments had been analyzed. Results: The grazing exclusion significantly increased total N concentration in the surface soil (0-20 cm), and increased plant height, coverage (P < 0.05) and aboveground biomass. Specifically, A. sparsifolia recovered faster both in individual and community levels than L. ruthenicum did after exclusion. There was no difference in response to N addition gradients between the two plants. Conclusions: Our findings suggest that it is exclusion rather than N addition that has greater impacts on soil properties and plant community in desert steppe. Present N deposition level has no effect on plant community of desert steppe based on short-term experimental treatments. [ABSTRACT FROM AUTHOR]

Excessive protein consumption (EPC) could increase the gastrointestinal burden and impair gut motility. The present study was designed to explore the improvement of chitosan (CTS) and chitosan oligosaccharide (COS) on colonic motility and serum metabolites in rats after EPC. The results of in vivo experiments fully proved that CTS and COS could improve gut motility and reverse the serum metabolites in rats as indicated by LC-MS/MS analysis, and the COS group even showed a better effect than the CTS group. Furthermore, short-chain fatty acids (SCFAs), which could promote gut motility, were also increased to alleviate EPC-induced constipation after supplementation with CTS or COS. In addition, CTS and COS could decrease the concentration of ammonia in serum and down-regulate the levels of H 2 S and indole. In summary, the present study revealed that CTS and COS could produce SCFAs, improve the colonic motility in rats, reverse the levels of valine, adenosine, cysteine, 1-methyladenosine, indole, and uracil, and enhance aminoacyl-tRNA biosynthesis and valine, leucine and isoleucine degradation. The present study provides novel insights into the potential roles of CTS and COS in alleviating the adverse effects of EPC. [Display omitted] • COS was superior to CTS in relieving the negative effects of EPC. • The levels of SCFAs were increased by both CTS and COS to improve colonic motility. • CTS and COS reversed the changes in serum metabolite profiles caused by EPC. • Both CTS and COS decreased the levels of serum ammonia, H 2 S, and indole. [ABSTRACT FROM AUTHOR]

In the present study, a fucoidan fraction (ANP-3) was isolated from Ascophyllum nodosum , and the combined application of desulfation, methylation, HPGPC, HPLC-MSn, FT-IR, GC–MS, NMR, and Congo red test elucidated ANP-3 (124.5 kDa) as a triple-helical sulfated polysaccharide constituted by →2)-α-Fuc p 3 S -(1→, →3)-α-Fuc p 2 S 4 S -(1→, →3,6)-β-Gal p 4 S -(1→, →3,6)-β-Man p 4 S -(1→, →3,6)-β-Gal p 4 S -(1→，→6)-β-Man p -(1→, →3)-β-Gal p -(1→, α-Fuc p -(1→, and α-GlcA p -(1→ residues. To better understand the relationship between the fucoidan structure of A. nodosum and protective effects against oxidative stress, two fractions ANP-6 and ANP-7 were used as contrast. ANP-6 (63.2 kDa) exhibited no protective effect against H 2 O 2 -induced oxidative stress. However, ANP-3 and ANP-7 with the same molecular weight of 124.5 kDa could protect against oxidative stress by down-regulating reactive oxygen species (ROS) and malondialdehyde (MDA) levels and up-regulating total antioxidant capability (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. Then metabolites analysis indicated that arginine biosynthesis and phenylalanine, tyrosine, and tryptophan biosynthesis metabolic pathways and metabolic biomarkers such as betaine were involved in the effects of ANP-3 and ANP-7. The better protective effect of ANP-7 compared to that of ANP-3 could be attributed to its relatively higher molecular weight, sulfate substitution and →6)-β-Gal p -(1→ content, and lower uronic acid content. [Display omitted] • The ANP-3 backbone mainly consisted of →3)-α-Fuc p 2 S 4 S -(1→ and →2)-α-Fuc p 3 S -(1→. • ANP-3 and ANP-7 with higher-MWs could reduce oxidative stress while ANP-6 could not. • ANP-3 and ANP-7 inhibited oxidative stress by modulating arginine biosynthesis. • ANP-7 with high sulfate content and molecular weight exhibited a stronger effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lycium barbarum arabinogalactan (LBP-3) can be utilized by Bacteroidetes species. • Of 10 tested species, P. vulgatus and B. caccae are more powerful to utilize LBP-3. • P. vulgatus and B. caccae preferred to Ara and Gal residues in LBP-3, respectively. • Oligosaccharides generated by P. vulgatus and B. caccae were identified by LC-MS n. • Their fermentation products with mono/oligo-saccharides influence others' growths. The present study investigated the utilization of an arabinogalactan from Lycium barbarum (LBP-3) by intestinal Bacteroidetes species. The mixed-culture assay showed 58.4 % LBP-3 was utilized, and Bacteroides caccae and Phocaeicola vulgatus utilized more LBP-3 in single-culture compared to others. During in vitro fermentation of LBP-3, P. vulgatus favored arabinose while B. caccae preferred galactose. Moreover, 9 and 25 oligosaccharides were identified by HPLC-MS n in conditioned media (CM) derived from B. caccae and P. vulgatus , respectively. All of 3 tested Parabacteroides species (P. distasonis , P. goldsteinii , and P. johnsonii) markedly proliferated in CM of B. caccae and P. vulgatus , and proliferations of B. uniformis , B. finegoldii , B. ovatus and B. thetaiotaomicron also increased significantly in CM of B. caccae. The study suggests that the ability of Bacteroidetes species to degrade LBP-3 and sheds light on cooperative interactions of Bacteroides, Phocaeicola , and Parabacteroides species in the presence of LBP-3. [ABSTRACT FROM AUTHOR]

Drought seriously endangers the development of agro‐pastoral ecotone in arid and semi‐arid regions. However, drought evolution characteristics of semi‐arid sandy grassland and its drivers are not well understood in the complex climate change context. Thus, in this paper, the revised standardized precipitation evaporation indices on one‐month (SPEI‐1) and growing‐season (SPEI‐6) scale, flash drought and dry spells (DS) were calculated as drought indicators, and the temporal variabilities and meteorological drivers of drought in Horqin Sandy Land during the growing period (April–September) from 2007 to 2021 were studied. The results showed that SPEI‐1 and SPEI‐6 exhibited negative trends and periodic change. This drought aggravation was manifested in increased grades and numbers of drought months. Flash droughts can occur every month during the growing season. And its occurrence was not only positively correlated with all drought events in frequency but also synchronized in time. The increased number of DS showed an asymmetrical shift towards 7‐day‐and‐longer DS. SPEI sensitivity to precipitation (P) was noticeably higher than to atmospheric evapotranspiration demand (AED) at both monthly and growing season scales. SPEI sensitivity to AED was modulated by P amounts, which was higher during low P period. Apart from the amounts of P and AED, their temporal variability also strongly determined how they affect the drought severity. P was also the main driver for flash drought and long DS, but AED with larger amount and higher variability is the reason for their aggravation. Our results demonstrate the complexity of drought intensification in semi‐arid sandy grasslands and highlight the important role of AED anomalies in it. [ABSTRACT FROM AUTHOR]

Although numerous polysaccharides have demonstrated potential immunostimulatory activities in in vitro models, only a few of them successfully stimulate the immune system in vivo. In order to explore the possible reasons for the activity loss of polysaccharides in in vivo models, the immunostimulatory activities in vitro and in vivo and the digestion behavior of a polysaccharide from Cyclina sinensis (CSP) were investigated in the present study. CSP showed obvious immunostimulatory activity in a RAW 264.7 cell model. In in vitro experiment, CSP did not exhibit cytotoxicity at concentrations of ≤10 µg/ml, and significantly increased NO production at concentrations of 0.4–10 µg/ml, suggesting CSP processes immunostimulatory activity in vitro. Further investigation using simulated digestion model indicated that CSP could bind with the protein in the digestive fluids to form precipitate in both the stomach and small intestine, and it could be seriously degraded by amylase during the digestion in the small intestine. Furthermore, the in vivo immunostimulatory activity evaluation demonstrated CSP had no effect on immunosuppressed mice as indicated by the body weight, thymus and spleen indexes, and TNF‐α, IL‐1β, IL‐6, and IL‐10 mRNA expression. Thus, the present study indicates that the degradation and precipitation of CSP in the digestive tract are the possible reasons for the activity loss of CSP after digestion. Practical Application: Cyclina sinensis is the common aquatic shellfish in China and plays an important role in the marine aquaculture industry. Cyclina sinensis polysaccharide (CSP) is the main active component of C. sinensis. The structure characterization and immunostimulatory activity of a purified fraction of CSP (CSP‐1) and the effect of digestion on CSP and its immunostimulatory activity were studied. The result of this study promotes the understanding of the nutritional function effects and provides a scientific reference for the rational development and high‐value utilization of C. sinensis. [ABSTRACT FROM AUTHOR]

• Bacteria and eukaryota diversity increased with increasing longitude and elevation. • Archaeal diversity decreased slightly with increasing elevation. • Some phyla diversity patterns are individually inconsistent with the overall trend. • Geographic distance contributed more than environmental factors to soil microbes. • More intra-domain than inter-domain links within the soil microbial network. Recent studies show that different microorganisms, especially bacteria and fungi, exhibit contrasting latitudinal, longitudinal, and altitudinal diversity patterns at a global scale, but little is known about biogeographic patterns in desert ecosystems. In this study, we chose a narrow geographic channel, namely the deserts of northern China's Hexi Corridor as the study area. Based on field survey and next-generation sequencing (Illumina MiSeq PE300 Platform), to map soil microbial geographic diversity patterns in this area and further determine the main driving factors responsible for shaping the soil microbial community. The results show that bacteria and eukaryotic diversity increased linearly with increasing longitude and altitude, but decreased with increasing latitude in the Hexi Corridor deserts, whereas archaeal diversity showed little change along these geographic gradients. Some individual phyla within the bacterial, archaeal, and eukaryota communities were not always consistent with collective trends, e.g., for the α-diversity of the ten most dominant bacterial phyla, only six phyla showed a statistically significant increase with altitude. The soil microbial community composition was jointly shaped by geographic distance and environmental variables (regional climatic factors and local edaphic variables). The effect of geographic distance on the soil microbial community composition was slightly stronger than that of the environmental variables. Intra-domain links were stronger than inter-domain links in the soil microbial network of the Hexi Corridor deserts, and these links were mostly positive. Although bacteria formed more connections than both archaea and eukaryotes, removing the archaea resulted in a lower natural connectivity, suggesting that the archaea were the core group for building this desert region's soil microbial co-occurrence network. Taken together, these findings deepen our understanding of regional-scale soil microbial diversity patterns in this desert ecosystem. [ABSTRACT FROM AUTHOR]

Caulerpa lentillifera (Bryopsidophyceae, Chlorophyta) is an edible seaweed attracting great attention for its expansion of farming scale and increasing consumption in these years. In the present study, a sulfated polysaccharide (CLSP-2) was isolated and separated from C. lentillifera , and its chemical structure was elucidated by a series of chemical and spectroscopic methods. Among these methods, mild acid hydrolysis and photocatalytic degradation were applied to release mono- and oligo-saccharide fragments which were further identified by HPLC-MSn analysis, affording the information of the sugar sequences and the sulfate substitution in CLSP-2. Results indicated that the backbone of CLSP-2 was constructed of →6)-β-Man p -(1→ with sulfated branches at C2, which were comprised of prevalent →3)-β-Gal p 4S-(1→, →3)-β-Gal p 2,4S-(1→, and minor Xyl. In addition, the virus neutralization assay revealed that CLSP-2 could effectively protect HeLa cells against SARS-CoV-2 infection with an IC 50 of 48.48 μg/mL. Hence, the present study suggests CLSP-2 as a promising agent against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Mowing and burning, two common human disturbance methods, have different impacts on the soil fungal and bacterial communities of sandy land ecosystems in semiarid areas. Thus, the effects of long-term mowing and burning on plant and soil microbial communities in the semiarid Horqin Sandy Land are unclear. In this study, the effects of soil microbial community structure from mowing and burning on plant and soil microbial communities over six years were assessed by high-throughput sequencing. First, we found that mowing and burning significantly reduced vegetation coverage (V) (p < 0.05), and burning significantly increased plant Shannon–Wiener diversity (H), Pielou evenness (E), and Simpson dominance (λ) indices (p < 0.05). Second, the two human disturbances markedly affected fungal diversity and abundance more than bacterial diversity and abundance. In fungi, burning significantly reduced beta diversity (p < 0.05) and the relative abundance of Basidiomycota (p < 0.05) but markedly increased the relative abundance of Ascomycota and Mortierellomycota. Third, redundancy analysis (RDA) showed that vegetation coverage was a significant factor in bacterial species distribution (p < 0.05). For fungi, the significant factors were species richness (S) and vegetation coverage (p < 0.01). Taken together, these data suggest that long-term mowing and burning have more of an effect on soil fungal communities than bacteria in a semiarid sandy land, improving our understanding of how terrestrial ecosystems respond to human disturbances and providing guidance for the management and restoration of sandy desertification. • Mowing significantly reduced vegetation coverage. • Burning could change the plant community diversity. • Mowing and burning markedly affected fungal diversity and abundance more than bacteria. • Vegetation coverage was the significant factor in bacteria species distribution. • Fungal community was more easily influenced by plant community diversity. [ABSTRACT FROM AUTHOR]

Chondroitin sulfate (CS) is widely known for its various biological activities which are closely related to the sulfate substitution and the molecular weight. Effective degradation methods without striping sulfate groups are in a need. In the present study, a photocatalytic degradation method using H 2 O 2 and TiO 2 has been developed and it could decrease the average molecular weight of CS into 5 kDa within 6 h. The chemical composition of CS before and after degradation were compared by FT-IR, NMR, etc. , and no removement of sulfate group was observed. Then the identification of the oligosaccharides in the degradation product by mass spectroscopy revealed that glucuronic acid or its derivative, arabinuronic acid, was at most of the reducing ends, and the depolymerization mechanism was proposed. Furthermore, the absorption of CS in rats was enhanced by the degradation while the excertion profile of the degradation product was similar to that of CS. [Display omitted] • A photocatalytic method is developed for chondroitin sulfate (CS) degradation. • It could depolymerize CS to 5 kDa within 6 h without stripping sulfate groups. • Most of oligosaccharide have glucuronic acid or its derivative at reducing ends. • Gut microbiota metabolize CS and its degradation product (3 kDa) at a similar level. [ABSTRACT FROM AUTHOR]

• 4300 km long transects were established in the ecologically fragile areas of China. • Soil C:N:P stoichiometry in ecologically fragile areas was well-constrained. • C:N:P stoichiometry differed among the areas in response to environmental changes. • Climate and vegetation factors were the key drivers of soil C:N:P stoichiometry. Researchers are paying increasing attention to soil stoichiometry (carbon:nitrogen:phosphorus (C:N:P) ratios) in efforts to explore biogeochemical cycles, but little is known about the spatial pattern, implications, and driving factors of this stoichiometry in large, ecologically fragile areas. To explore these factors, we established three transects that covered a total length of about 4300 km in ecologically fragile areas of China, and sampled at intervals of about 25 km. These transects covered the karst area and the agro-pastoral ecotone of southwestern China, the Qinghai-Tibet Plateau, the Loess Plateau, and the forest-grassland ecotone. We collected 312 soil samples to a depth of 30 cm from 156 plots. The soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the ecologically fragile areas showed strong coupling relationships. Soil C:N:P was 51:4:1 to a depth of 30 cm, which is lower than the average global C:N:P (111:8:1). SOC and TN concentrations at 0 to 20 cm were significantly higher than that at 20 to 30 cm, but TP did not differ significantly among depths. SOC, TN, and TP concentrations were highest in the agro-pastoral ecotone, and were lowest in the Loess Plateau. C:N, C:P, and N:P were highest in the karst area. C:N were lowest in the Qinghai-Tibet Plateau, and C:P and N:P were lowest in the Loess Plateau. The spatial pattern of C, N, and P stoichiometry along environmental gradients was variable. The contributions to explaining the soil stoichiometry were highest for climate (21.7%), vegetation (8.9%), soil properties (6.4%), and topography (0.6%) to a depth of 20 cm, versus vegetation (35.9%), climate (5.3%), soil properties (3.3%), and topography (2.1%) at 20 to 30 cm. The results provide new insights into the biogeochemical cycles of C, N, and P and guidance for their impacts on ecological restoration in ecologically fragile areas. [ABSTRACT FROM AUTHOR]

Plant litter derived from the living biomass is the primary source of soil carbon (C). However, the contribution and the mechanism of plant litter production to soil C remains uncertain in aeolian regions. In this study, the relationship between plant biomass, litter mass, and soil C content was analyzed after a spatial field investigation in Horqin sandy land, northeast China. Long-term monitoring of wind speed and plant litter production was also conducted in three habitats (mobile dune, semi-fixed dune, and fenced grassland). The soil C content was significantly affected by belowground biomass and belowground litter mass but not aboveground biomass and aboveground litter. The litter production in the desertified habitat (mobile dune and semi-fixed dune) significantly differed with that of the undesertified habitat (fixed dune and fenced grassland). In mobile dune, 38% of the aboveground primary production was lost, while there was a distinct enrichment of plant litter in semi-fixed dune and fenced grassland. Wind events (wind speeds of 7 and 8 m s−1) at the end of the growing season significantly affected litter production rate, and wind was a major driver for litter transportation between habitats. In summary, plant litter production can be affected by wind events, and this influence differs among habitats in degraded grassland, leading to spatial heterogeneity of soil C accumulation. These results can strengthen the understanding of the relationship between soil properties and plant litter production in aeolian regions and furthermore, can provide information for ecological restoration of different types of desertified land, especially for the soil C accumulation. Plant litter is the major source for soil organic matter accumulation. In degraded sandy grasslands in semi-arid regions, wind is a visible factor which transported the aboveground litter from regions with lower vegetation coverage (e.g. mobile dune or semi-fixed dune) to regions with higher vegetation coverage (e.g. fixed dune or fenced grassland), which means that, wind is the driving force for the source-sink relationships of plant litters. There remains no clear description of the influence of wind events on litter production and litter distribution. The contribution of plant litter production to soil C remains uncertain in aeolian regions. The schematic diagram strengthened the understanding of the relationship between soil properties and plant litter production, and providing important information for ecological restoration in semi-arid sandy grasslands. [Display omitted] [ABSTRACT FROM AUTHOR]