The cumulative impact of temperature and nitrogen availability on the potential nitrogen fixation and extracellular polymeric substances secretion by Dolichospermum.

Nitrogen-fixing cyanobacteria not only cause severe blooms but also play an important role in the nitrogen input processes of lakes. The production of extracellular polymeric substances (EPS) and the ability to fix nitrogen from the atmosphere provide nitrogen-fixing cyanobacteria with a competitive advantage over other organisms. Temperature and nitrogen availability are key environmental factors in regulating the growth of cyanobacteria. In this study, Dolichospermum (formerly known as Anabaena) was cultivated at three different temperatures (10 °C, 20 °C, and 30 °C) to examine the impact of temperature and nitrogen availability on nitrogen fixation capacity and the release of EPS. Initially, confocal laser scanning microscopy (CLSM) and the quantification of heterocysts at different temperatures revealed that lower temperatures (10 °C) hindered the differentiation of heterocysts under nitrogen-deprived conditions. Additionally, while heterocysts inhibited the photosynthetic activity of Dolichospermum, the secretion of EPS was notably affected by nitrogen limitation, particularly at 30 °C. Finally, real-time quantitative polymerase chain reaction (qPCR) was used to measure the expression of nitrogen-utilizing genes (ntcA and nifH) and EPS synthesis-related genes (wzb and wzc). The results indicated that under nitrogen-deprived conditions, the expression of each gene was upregulated, and there was a significant correlation between the upregulation of nitrogen-utilizing and EPS synthesis genes (P < 0.05). Our findings suggested that Dolichospermum responded to temperature variation by affecting the formation of heterocysts, impacting its potential nitrogen fixation capacity. Furthermore, the quantity of EPS released was more influenced by nitrogen availability than temperature. This research enhances our comprehension of interconnections between nitrogen deprivation and EPS production under the different temperatures.

How does exotic Spartina alterniflora affect the contribution of iron-bound organic carbon to soil organic carbon in salt marshes?

Iron-bound organic carbon (OC-FeR) is important for the stability of soil organic carbon (SOC) in salt marshes, and the Spartina alterniflora invasion reshaped local salt marshes and changed the SOC pool. To evaluate the effects of S. alterniflora invasion on the contribution of OC-FeR to SOC, we determined the OC-FeR content and soil characteristics in the 0-50 cm soil profile along the vegetation sequence, including mudflats (MF), S. alterniflora marshes established in 2003 (SA03) and 1989 (SA89), the ecotone of S. alterniflora and Phragmites australis (SE), S. salsa marsh (SS), and P. australis marsh (PA). The SOC content was 6.55-17.5 mg g-1 in the S. alterniflora marshes. Reactive iron oxides (Fed, Feo, Fep) accumulated significantly in the S. alterniflora and P. australis salt marshes. PA and S. alterniflora marshes had higher DOC contents of 0.28-0.77 mg g-1. The OC-FeR content in the 0-50 cm soil profile in these ecosystems ranged from 0.3 to 3.29 mg g-1, with a contribution to the SOC content (fOC-FeR) of approximately 11 %, which was highest in SA03 (16.3 % ~ 18.8 %), followed by SA89, SE, and PA. In addition, the molar ratios of OC-FeR to Fed were <1, indicating that the iron oxides were associated with SOC through sorption more than coprecipitation. According to the structural equation model, SOC, DOC and iron oxides were the direct driving factors of OC-FeR formation, while the vegetation zone indirectly functioned by regulating organic C inputs, iron oxide formation, and pH. This study suggested that S. alterniflora invasion promotes iron-bound organic carbon accumulation by increasing organic C inputs and regulating iron oxide formation in salt marshes, but such promotion will degenerate with development duration.

How does Microcystis aeruginosa respond to elevated temperature?

Cyanobacteria and their toxins widely exist in freshwater ecosystems. Microcystis aeruginosa is among dominant bloom-forming cyanobacteria. Water temperature is a key factor influencing the life cycle of M. aeruginosa. We simulated elevated temperature (4-35 °C) experiment and cultured M. aeruginosa during the overwintering, recruitment and rapid growth phases. The results showed that M. aeruginosa recovered growth after overwintering at 4-8 °C and recruited at 16 °C. The total extracellular polymeric substance (TEPS) concentration increased rapidly at 15 °C. The actual quantum yield of photosystem II (Fv'/Fm') peaked at 20 °C during the rapid growth phase, and the optimum temperature of M. aeruginosa growth was 20-25 °C. Additionally, TEPS and microcystins (MCs) secretion peaked at 20-25 °C. The cell density accumulated rapidly from 26 °C to 35 °C. Furthermore, enzymes of RuBisCO and FBA related to photosynthetic activity were confirmed to contribute to the metabolism, as well as mcyB gene was affected by elevated temperature. Our results provide insights of the physiological effects and metabolic activity during annual cycle of M. aeruginosa. And it is predicted that global warming may promote the earlier recruitment of M. aeruginosa, extend the optimum growth period, enhance the toxicity, and finally intensify M. aeruginosa blooms.

Effects of extracellular polymeric substances on the aggregation of Aphanizomenon flos-aquae under increasing temperature.

Aphanizomenon flos-aquae (A. flos-aquae) blooms are serious environmental and ecological problems. Extracellular polymeric substances (EPSs) are among the most important indicators for the growth and aggregation of A. flos-aquae. In this study, the secretion of the EPS matrix under temperature rise (7-37°C) was investigated and the role of this matrix in A. flos-aquae aggregation was quantified. First, when the temperature increased, the aggregation ratio increased from 41.85 to 91.04%. Meanwhile, we found that when soluble EPSs (S-EPSs), loosely bound EPSs (LB-EPSs), and tightly bound EPSs (TB-EPSs) were removed successively, the aggregation ratio decreased from 69.29 to 67.45%, 61.47%, and 41.14%, respectively. Second, the content of polysaccharides in the EPS matrix was higher than the content of proteins under temperature change. The polysaccharide in TB-EPSs was closely related to the aggregation ability of A. flos-aquae (P < 0.01). Third, PARAFAC analysis detected two humic-like substances and one protein-like substance in EPSs. Furthermore, Fourier transforms infrared spectroscopy (FTIR) showed that with increasing temperature, the polysaccharide-related functional groups increased, and the absolute value of the zeta potential decreased. In conclusion, these results indicated that a large number of polysaccharides in TB-EPSs were secreted under increasing temperature, and the polysaccharide-related functional groups increased correspondingly, which reduced the electrostatic repulsion between algal cells, leading to the destruction of the stability of the dispersion system, and then the occurrence of aggregation. This helps us to understand the process of filamentous cyanobacterial aggregation in lakes.

One-step fabrication and characterization of Fe3O4/HBPE-DDSA/INH nanoparticles with controlled drug release for treatment of tuberculosis.

In this study, Fe3O4/hyperbranched polyester-(2-dodecen-1-yl)succinic anhydride2-Dodecen-1-/isoniazid magnetic nanoparticles (Fe3O4/HBPE-DDSA/INH MNPs) with controlled drug release characteristics were synthesized successfully by a simple one-step method. Orthogonal experiments were performed to optimize the loading capacity and encapsulation efficiency of the MNPs. The structure of the Fe3O4/HBPE-DDSA/INH MNPs was characterized by 1H nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization mass spectrometry, Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, and superconducting quantum interference device measurements, while their properties were characterized based on swelling behavior observations, in-vitro release experiments, and cytotoxicity analysis. The results indicated that the fabricated Fe3O4/HBPE-DDSA/INH MNPs had a high drug-loading capacity and encapsulation efficiency. Further, the drug-release rate of the MNPs was higher in an acidic buffer, indicating that the MNPs were pH-responsive. Swelling studies revealed that the MNPs exhibited diffusion-controlled drug release, while in-vitro release studies revealed that the drug-release properties could be controlled readily, owing to the high encapsulation efficiency of the MNPs and the uniform dispersion of the drug in them. These results collectively suggest that this multifunctional nontoxic drug delivery system, which exhibits good magnetic properties and pH-triggered drug-release characteristics, should be suitable for the treatment of tuberculosis.

Estimating sedimentary organic matter sources by multi-combined proxies for spatial heterogeneity in a large and shallow eutrophic lake.

The multiple proxies involving elemental and stable isotope ratios (C/N, δ15N and δ13C) and biomarkers are powerful tools for estimating sedimentary organic matter (SOM) sources. However, the systematic and reasonable evaluation of organic matter sources existing with serious spatial heterogeneity in large, shallow and eutrophic lakes is still far from clear. Samples of sediments, aquatic plants and particulate organic matter (POM) collected from different ecotype regions of Taihu Lake, China, including algae-type lakeshore, grass-type lakeshore, algae-grass-type lakeshore, inflow rivers and estuary, groove reed zone, offshore and central regions, were analyzed for their SOM sources via elemental and stable isotope ratios (C/N, δ15N and δ13C), n-alkanes and fatty acids (FA). More depleted δ13CTOC values (-26.3‰ to -25.4‰) and higher relative percentages of odd n-alkanes (C26 to C35) and long-chain FA (C24:0 to C32:0) clarified the influence of inflow rivers carrying terrestrial inputs on SOM. The higher relative percentages of n-alkanes from C14 to C20, FA (C16:0), and polyunsaturated FA (C18:2 and C18:3) in the reed belt of the groove demonstrated that some special terrain was important for the accumulation of algae-derived OM in sediments. Short-chain and middle-chain biomarker compounds revealed a large contribution from macrophytes in the grass-type region and an obvious algae-derived organic matter accumulation in the algae-type region, respectively. However, some overlapping ranges of C/N, δ15N and δ13C among aquatic plants, the ubiquity of lipid biomarkers compounds, anthropogenic influences, meteorological factors and lake topography caused some biased identification results for partial samples using different indicators. These biased identifications were mainly embodied in the source category and contribution difference based on principal component analysis and an end-member mixing model. Therefore, the estimation of SOM sources by multiple proxies cannot be uniformly applied in large freshwater lakes. The systematic investigation and comprehensive understanding of the different ecotypes and their surrounding environments are the important links in the identification of SOM sources via multiple indicators.

Incorporation of DDR2 clusters into collagen matrix via integrin-dependent posterior remnant tethering.

Cell-matrix interactions play critical roles in cell adhesion, tissue remodeling and cancer metastasis. Discoidin domain receptor 2 (DDR2) is a collagen receptor belonging to receptor tyrosine kinase (RTK) family. It is a powerful regulator of collagen deposition in the extracellular matrix (ECM). Although the oligomerization of DDR extracellular domain (ECD) proteins can affect matrix remodeling by inhibiting fibrillogenesis, it is still unknown how cellular DDR2 is incorporated into collagen matrix. Using 3-dimentional (3D) imaging for migrating cells, we identified a novel mechanism that explains how DDR2 incorporating into collagen matrix, which we named as posterior remnant tethering. We followed the de novo formation of these remnants and identified that DDR2 clusters formed at the retracting phase of a pseudopodium, then these clusters were tethered to fibrillar collagen and peeled off from the cell body to generate DDR2 containing posterior remnants. Inhibition of ß1-integrin or Rac1 activity abrogated the remnant formation. Thus, our findings unveil a special cellular mechanism for DDR2 clusters incorporating into collagen matrix in an integrin-dependent manner.

Lipid-lowering effects of oleanolic acid in hyperlipidemic patients.

Oleanolic acid (OA) is a pentacyclic triterpenoid compound extracted from olea europaeal, a traditional Chinese medicine herb. OA has been used in the clinic as a hepatoprotective medicine in China since 1970s. In our previous study, we observed that OA could ameliorate hyperlipidemia in animal models. In the present study, we conducted a small-scale clinical trial to evaluate the hypolipidemia effect of OA in hyperlipidemic patients. Hyperlipidemic patients were administrated with OA for four weeks (4 tablets once, three times a day). The blood samples of the patients were collected before and after OA treatment. The biological parameters were measured. Furthermore, three patients' blood samples were studied with DNA microarray. After OA administration, the TC, TG, and HDLC levels in serum decreased significantly. DNA microarray analysis results showed that the expressions of 21 mRNAs were significantly changed after OA treatment. Bioinformatics analysis showed 17 mRNAs were up-regulated and 4 mRNAs were down-regulated significantly after OA treatment. Five mRNAs (CACNA1B, FCN, STEAP3, AMPH, and NR6A1) were selected to validate the expression levels by qRT-PCR. Therefore, OA administration differentially regulated the expression of genes involved in lipid metabolism. The data showed a clinical evidence that OA could improve hyperlipidemia and also unveiled a new insight into the molecular mechanisms underlying the pharmacological effect of OA on hyperlipidemia.

High-Density Infiltration of V-domain Immunoglobulin Suppressor of T-cell Activation Up-regulated Immune Cells in Human Pancreatic Cancer.

V-domain immunoglobulin suppressor of T-cell activation (VISTA) is constitutively expressed in hematopoietic lineage and is highly up-regulated in tumor infiltrated myeloid cells and regulatory T-cells in animal models. However, its expression in human pancreatic tumor microenvironment remains unknown. In this research, we aimed at the expression of VISTA in human pancreatic cancer samples. METHODS: We performed immunohistochemistry to determine VISTA expression in human pancreatic cancer samples. RESULTS: We found that 88.46% of the patients showed high-density infiltration of polymorphonuclear neutrophils and mononuclear immune cells with up-regulated expression of VISTA in cancer tissues, especially in the necrotic foci. Interestingly, it was minimally expressed in pancreatic cancerous cells and was not detectable in either normal ducts or islet cells in cancerous or normal pancreatic tissues. CONCLUSIONS: We conclude that VISTA is predominantly expressed and up-regulated in the high-density infiltrated immune cells but minimal in human pancreatic cancerous cells. Our results for the first time highlight pancreatic immunosuppressive tumor microenvironment contributed by VISTA and its potential as a prominent target for pancreatic cancer immunotherapy.

Distributions of four taste and odor compounds in the sediment and overlying water at different ecology environment in Taihu Lake.

Organic matter-induced black blooms, such as cyanobacterial and vegetation blooms, are a serious ecosystem disasters that have occurred in Taihu Lake. After large-scale outbreaks of blooms in eutrophic water, a large number of cyanobacterial and vegetation residue accumulate in the coastal areas, and rapidly fermented into odorous compounds. In this study, four taste and odor compounds have been analyzed in sediments and overlying water of different ecology environment in Taihu Lake. High concentrations of DMDS (up to 7165.25 ngg-1 dw-1), DMTS (up to 50.93 ngg-1 dw-1), ß-cyclocitral (up to 5441.69 ngg-1 dw-1), ß-ionone (up to 1669.37 ngg-1 dw-1) were detected in sediments. Also, the spatial distributions of DMDS, DMTS, ß-cyclocitral and ß-ionone in the sediments were investigated. As the depth of sediment increases, nutrients and odorous compounds are greatly reduced. The results showed that during the degradation of cyanobacterial and vegetation residues, DMDS, DMTS, ß-cyclocitral, ß-ionone and nutrients are gradually released. In addition, when assessing the source of odorous compounds in overlying water, it should also be considered that it may be released from the sediment. This study shows that odorous compounds are ubiquitous in near-shore zones Taihu Lake, and may take potential hazard to aquatic ecosystems.

3-Acetyl-oleanolic acid ameliorates non-alcoholic fatty liver disease in high fat diet-treated rats by activating AMPK-related pathways.

3-Acetyl-oleanolic acid (3Ac-OA) is a derivative of oleanolic acid (OA), which has shown therapeutic beneficial effects on diabetes and metabolic syndrome. In this study we investigated whether 3Ac-OA exerted beneficial effect on non-alcoholic fatty liver disease (NAFLD) in rats and its potential underlying mechanisms. Treatment with 3Ac-OA (1-100 µmol/L) dose-dependently decreased the intracellular levels of total cholesterol (TC) and triglyceride (TG) in FFA-treated primary rat hepatocytes and human HepG2 cell lines in vitro. Furthermore, oil red staining studies showed that 3Ac-OA caused dose-dependent decrease in the number of lipid droplets in FFA-treated primary rat hepatocytes. SD rats were fed a high fat diet (HFD) for 6 weeks and subsequently treated with 3Ac-OA (60, 30, 15 mg·kg-1·d-1) for 4 weeks. 3Ac-OA administration significantly decreased the body weight, liver weight and serum TC, TG, LDL-C levels in HFD rats. Furthermore, 3AcOA administration ameliorated lipid accumulation and cell apoptosis in the liver of HFD rats. Using adipokine array analyses, we found that the levels of 11 adipokines (HGF, ICAM, IGF-1, IGFBP-3, IGFBP-5, IGFBP-6, lipocalin-2, MCP-1, M-CSF, Pref-1 and RAGE) were increased by more than twofold in the serum of 3Ac-OA-treated rats, whereas ICAM, IGF-1 and lipocalin-2 had levels increased by more than 20-fold. Moreover, 3Ac-OA administration significantly increased the expression of glucose transporter type 2 (GLUT-2) and low-density lipoprotein receptor (LDLR), as well as the phosphorylation of AMP-activated protein kinase (AMPK), protein kinase B (AKT) and glycogen synthase kinase 3ß (GSK-3ß) in the liver tissues of HFD rats. In conclusion, this study demonstrates that 3Ac-OA exerts a protective effect against hyperlipidemia in NAFLD rats through AMPK-related pathways.

The effects of oleanolic acid on atherosclerosis in different animal models.

In the present study, three animal models, including C57BL/6J mice, low-density lipoprotein receptor knockout (LDLR-/-) mice, and rabbit that mimicked atherosclerosis, were established to investigate the inhibitory effect of oleanolic acid (OA) on atherosclerosis. In rabbit model, serum total cholesterol (TC), triglyceride, low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C) were measured. Carotid artery lesions were isolated for histological analysis. The red oil O and hematoxylin-eosin staining in liver were examined. The messenger ribonucleicacid (mRNA) levels of PPARγ, AdipoR1, and AdipoR2 related to lipid metabolism were determined. Compared with model group, OA and atorvastatin significantly lowered the levels of TC and LDL-C. The result of red oil O staining showed that OA and atorvastatin had similar effect on reducing the accumulation of lipid. Histological result demonstrated that OA reduced the thickness of intima. AdipoR1 was markedly increased, while AdipoR2 was remarkably decreased in OA group compared with that in the control group of the rabbit model. In LDLR-/- mouse model, lipid parameters in blood and mRNA levels of PPARγ, AdipoR1, and AdipoR2 were measured. It was found that OA exhibited similar effects as atorvastatin including reduced TG, LDL-C, and enhanced HDL-C. Notably, OA elevated the levels of AdipoR1 and PPARγ. At the same time, OA decreased TC and LDL-C in C57BL/6J mice model. Our results in three different animal models all revealed that OA retarded the development of atherosclerosis by influencing serum lipid levels, lipid accumulation in liver and intimal thickening of artery. And the underlying mechanism of OA on atherosclerosis may involve in lipid metabolism genes: PPARγ, AdipoR1, and AdipoR2.

MAD ointment ameliorates Imiquimod-induced psoriasiform dermatitis by inhibiting the IL-23/IL-17 axis in mice.

Psoriasis is a chronic auto-immune inflammation disease with skin lesions and abnormal keratinocyte proliferation. The IL-23/IL-17 axis plays an important role in the pathogenesis of psoriasis. Madecassoside (MAD) was the most important constituents isolated from Centella asiatica, which has long been used in dermatology, and it is supposed that MAD may have effects on psoriasis. In the present study, the BALB/c mice ear and back skin received IMQ for 6 consecutive days to induce psoriasis-like dermatitis. MAD ointment was applied 6h later after IMQ treatment, and the IL-23/IL-17 pathway was investigated. The HE staining, BrdU and Psoriasis Area and Severity Index (PASI) were used to score the severity of keratinocyte proliferation and inflammation of the skin. Real-time PCR and Western Blot were used to detect the IL-23/IL-17 related cytokines. Flow Cytometry were applied to observe the numbers of Th17 cells. Daily application of IMQ for 6days on mouse ear skin and back skin induced psoriasis-like dermatitis. Real-time PCR showed that mRNA level of IL-23, IL-22, IL-17A were significantly decreased by MAD ointment treatment in ear skin. HE staining and BrdU incorporation implied that MAD ointment reduced keratinocyte proliferation. Flow Cytometry results showed MAD ointment decreased the numbers of Th17 cells. Thus, MAD ointment ameliorates Imiquimod-induced skin inflammation and abnormal keratinocyte through regulate the IL-23/IL-17 axis.

[Evolvement of soil quality in salt marshes and reclaimed farmlands in Yancheng coastal wetland].

Through vegetation investigation and soil analysis, this paper studied the evolvement of soil quality during natural vegetation succession and after farmland reclamation in the Yancheng coastal wetland of Jiangsu Province. Along with the process of vegetation succession, the soil physical, chemical, and biological properties in the wetland improved, which was manifested in the improvement of soil physical properties and the increase of soil nutrient contents, microbial biomass, and enzyme activities. Different vegetation type induced the differences in soil properties. Comparing with those in salt marshes, the soil salt content in reclaimed farmlands decreased to 0.01 - 0.04%, the soil microbial biomass and enzyme activities increased, and the soil quality improved obviously. The soil quality index (SQI) in the wetland was in the order of mudflat (0.194) < Suaeda salsa flat (0.233) < Imperata cylindrica flat (0.278) < Spartina alterniflora flat (0.446) < maize field (0.532) < cotton field (0.674) < soybean field (0.826), suggesting that positive vegetation succession would be an effective approach in improving soil quality.

[Influence of salt marsh vegetation on spatial distribution of soil carbon and nitrogen in Yancheng coastal wetland].

Soil samples under different salt marsh vegetations in Yancheng coastal wetland were collected, and their organic carbon (C) and total nitrogen (N) were determined, aimed to analyze the influence of salt marsh vegetation on the spatial distribution of soil carbon and nitrogen. The results showed that the organic C and total N contents in top soils varied from 1.71 to 7.92 g x kg(-1) and from 0.17 to 0.36 g x kg(-1), respectively, and there were significant differences among different vegetation zones. The top soils organic C and total N contents in vegetation zones were higher than those in mudflat without vegetation. In the soil profiles in vegetation zones, organic C and total N contents had a trend of decreasing with depth, but changed little below the depth of 15 cm. Soil organic C was significantly positively correlated with soil total N and C/N, but soil total N had no significant correlation with soil C/N.

[Emergy analysis on an added loop in Spartina alterniflora ecological engineering].

Based on the principle of multi-grade utilization of resources to get ecological, economic and social benefits of ecological engineering, this paper designed an added loop, following the Spartina alterniflora Ecological Engineering (SAEE). All the added loop design included SAEE, and the capsule was named SAEEC. In the added loop design, the Biological Mineral Liquid (BML) was made into antihyperlipidemia capsules, of which, the total flavonoids added up to 9.58 mg x g(-1). Emergy analysis method was applied to evaluate the SAEEC project. Compared with SAEE, the added loop design increased emergy investment ratio (EIR) by 1.37 fold, net economic benefit of the SAEEC by 2.13 fold, economic yield/input ratio by 1.46 fold, net emergy yield (NEY) by 3.18 fold, and net emergy yield ratio (EYR) by 2.20 fold, showing its more efficiency.