The Influence of Planting Sites On the Chemical Compositions of Chrysanthemum morifolium Flowers (Chuju) as Revealed by Py-GC/MS Combined with Multivariate Statistical Analysis.

Chuju, a cultivar of Chrysanthemum morifolium, has been traditionally cultivated for over 2000 years in China for both ornamental and medicinal purposes. To date, investigations into the chemical composition of this plant have indicated that it contains compounds with extensive biological activities, although detailed information on the chemical composition of Chuju remains scarce. In the present study, the chemical compositions of Chuju flowers were investigated across five sites in the core Chuju planting area in Anhui province, China. Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was used to explore variations in flower chemical fingerprints from different Chuju planting sites. The study identified approximately 200 components in Chuju flowers and stems, including high levels of fatty acids, lipids, polysaccharides and terpenoids. Multivariate statistical analysis indicated that 16 chemical compounds were influential determinants of the chemical fingerprint and could be used to distinguish two clusters in the five core planting areas. The established Py-GC/MS analytical workflow could provide a basis for determining the chemical fingerprints of Chuju and help elucidate that products contain a reproducible content of bioactive compounds and overall quality for potential development of health and medicinal purposes.

High plant species diversity enhances lignin accumulation in a subtropical forest of southwest China.

Plant species diversity (PSD) benefits soil organic carbon (SOC) accumulation, but mechanisms underlying the stimulative effects of PSD on SOC pools have not been well explored, especially in terms of how PSD impacts plant-derived C accumulation. Here, 45 plots covering a natural gradient of PSD ranging from 0.15 to 3.57 (Shannon's diversity index) were selected in a subtropical forest with calcareous soil to determine the pattern of and controls on the variation of plant-derived C as indexed by lignin phenols along with PSD. The absolute contents of lignin phenols ranged from 1.18 to 6.62 mg g-1 soil with an average of 2.48 ± 1.13 mg g-1 soil across the 45 plots. PSD significantly enhanced soil lignin accumulation via three mechanisms. First, PSD benefited lignin accumulation by stimulating plant detritus inputs. Second, PSD directly and indirectly increased reactive minerals, so that enhanced mineral protection of lignin. Third, decrease in microbial C limitation due to increased soil C availability resulted in lowered peroxidase activity and subsequently lignin degradation, which in turn benefited lignin accumulation. Our study provides mechanisms underlying SOC accumulation in response to increased PSD, which may be integrated into Earth system models in order to better predict SOC dynamics under PSD alteration.

The effects of exogenous amino acids on production of microcystin variants in Microcystis aeruginosa.

Dissolved free amino acids are a significant component of dissolved organic nitrogen (DON) in natural waterbodies. The effects of four amino acids (glutamic acid, phenylalanine, leucine, and arginine) on the growth and microcystins (MCs) production of Microcystis aeruginosa were studied in batch culture. The profiles of five MCs variants and the expression levels of target genes involved in MCs biosynthesis and nitrogen metabolism were measured. When amino acids were used as the sole nitrogen source instead of nitrate at different levels (0.5, 2.0 and 8.0 mg/L based on N) in BG-11 medium, algal cell growth and intracellular MCs quotas were inhibited slightly by the treatments with glutamic acid and arginine. The treatments with phenylalanine and leucine, on the other hand, had a strong inhibitory effect on algal cell growth and MCs production. Moreover, the concentrations of Chlorophyll a, phycocyanin and allophycocyanin in cells cultured in glutamic acid, leucine and phenylalanine were lower than those in the control group with nitrate as nitrogen source. The existence of leucine or phenylalanine can lead to a significant increase in the relative abundance of MCs variants structured with the corresponding amino acids. The expression of microcystin-producing gene mcyD was downregulated while the gene pipX associated with nitrogen metabolism was upregulated during the cultivation of M. aeruginosa with amino acids as sole nitrogen source. M. aeruginosa undergoes significant alterations due to exogenous amino acids and exhibits advanced strategies for MCs production.

Physiological and antioxidant responses of Euryale ferox salisb seedlings to microcystins.

Lake Taihu is the third largest freshwater lake located in eastern China. In recent years, it has experienced extensive cyanobacterial (Microcystis spp.) blooms that produce toxic microcystins (MCs), which may have acute and chronic hepatotoxic effects in animals and humans. Although the impact of MCs on both terrestrial and aquatic plants is well documented, the effects and underlying mechanisms of the harmful toxin MC-LR on Euryale ferox Salisb seedlings have rarely been reported. Thus, herein, the antioxidant response mechanisms and the biosynthesis of secondary metabolites during the exposure of E. ferox Salisb seedlings to varying MC-LR concentrations (0.05, 0.2, 1, and 5 µg/L) were thoroughly investigated after exposure periods (7, 14, 21 d). Our study revealed that the seedling growth was inhibited with increasing MC-LR exposure concentration that significantly induced at 1 µg/L and reached a maximum level at 5 µg/L, whereas the activity of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) in the seedling cells increased gradually with increasing MC-LR concentration and longer exposure time. The maximum malondialdehyde (MDA) content was 4.3-fold higher than that of the control group under an MC-LR concentration of 5.0 µg/L after 7 days of exposure treatment. The study of the seedling detoxification mechanism revealed that the content of total glutathione (tGSH) and reduced glutathione (GSH), as well as the activities of GSH sparse transferase (GST) and glutathione reductase (GR), increased to varying degrees and reached a maximum level at 1 µg/L. Therefore, the exposure to MC-LR can promote the accumulation of secondary metabolites and increase the activities of secondary metabolic enzymes in the seedlings. Further investigation of these antioxidative mechanisms will provide additional information for the identification and development of bio-indicators to evaluate the environmental impact of MCs on aquatic ecosystems.

All-in-One Deposition to Synergistically Manipulate Perovskite Growth for High-Performance Solar Cell.

Nonradiative recombination losses originating from crystallographic distortions and issues occurring upon interface formation are detrimental for the photovoltaic performance of perovskite solar cells. Herein, we incorporated a series of carbamide molecules (urea, biuret, or triuret) consisting of both Lewis base (-NH2) and Lewis acid (-C=O) groups into the perovskite precursor to simultaneously eliminate the bulk and interface defects. Depending on the different coordination ability with perovskite component, the incorporated molecules can either modify crystallization dynamics allowing for large crystal growth at low temperature (60°C), associate with antisite or undercoordinated ions for defect passivation, or accumulate at the surface as an energy cascade layer to enhance charge transfer, respectively. Synergistic benefits of the above functions can be obtained by rationally optimizing additive combinations in an all-in-one deposition method. As a result, a champion efficiency of 21.6% with prolonged operational stability was achieved in an inverted MAPbI3 perovskite solar cell by combining biuret and triuret additives. The simplified all-in-one fabrication procedure, adaptable to different types of perovskites in terms of pure MAPbI3, mixed perovskite, and all-inorganic perovskite, provides a cost-efficient and reproducible way to obtain high-performance inverted perovskite solar cells.

Study on the cyanobacterial toxin metabolism of Microcystis aeruginosa in nitrogen-starved conditions by a stable isotope labelling method.

In this study, the biosynthesis of microcystins (MCs) was investigated after long-term nitrogen-starved conditions in cyanobacterium Microcystis aeruginosa. The results demonstrated that the algal cells were able to survive in a non-growing state with nitrogen starvation for more than one month. The physiological properties of the algal cells were studied to elucidate the mechanisms of viability under nitrogen-deprivation conditions. After the state of nitrogen chlorosis, new toxins could be resynthesized and tracked using 15N-stable isotope-labelled nitrogen. Nitrogen starvation of nutritionally replete cells resulted in a significant increase of microcystin-LY (MC-LY), thereby suggesting that MC-LY may undergo catabolism to provide nitrogen or that MC-LY may be produced to play an important role in the cell in response to nitrogen deprivation. The rank order of different types of nitrogen in algal cells assimilation was N-ammonium > N-urea > N-nitrate > N-alanine. The relationship between the production of toxin variants and various environmental conditions is an interesting issue for future research and may help improve the understanding of the ecological role of cyanobacterial toxins.

Occurrence and ecological risk assessment of disinfection byproducts from chlorination of wastewater effluents in East China.

Effluents containing disinfection byproducts (DBPs) from wastewater treatment plants (WWTPs) may be discharged to the receiving water bodies or reused for irrigation, landscaping, and environmental supplies as well as a source to replenish groundwater. Thus the formation and risk of the DBPs in disinfected wastewater effluents should be concerned. In this study, the occurrence of 44 DBPs including 6 trihalomethanes (THMs), 9 haloaceticacids (HAAs), 2 haloketones (HKs), 9 halonitromethanes (HNMs), 9 haloacetonitriles (HANs) and 9 nitrosamines (NAs) was investigated in 12 chlorinated WWTP effluents from five cities of East China. The contribution of each class of DBPs to the total DBPs concentration and additive toxicity was calculated. The average concentrations of the 6 classes of DBPs were ranked as follows: HAAs (47.0 µg/L) > THMs (28.0 µg/L) > HANs (9.9 µg/L) > HNMs (2.9 µg/L) > HKs (0.79 µg/L) > NAs (0.69 µg/L). The significant positive correlations were observed between the formation of THMs and HAAs, THMs and HANs, as well as HAAs and HANs. The results showed that HAAs and THMs were the dominant DBPs on a mass concentration basis and accounted for 54% and 29%, respectively in the total measured DBPs, but they made a minor contribution to the calculated DBP-associated cytotoxicity. HANs and NAs dominated the DBP-associated cytotoxicity, accounting for 50% and 34% on an additive toxicity basis despite the minor contributions to the mass concentration with 10% and 1%, respectively. The risk quotients for three taxonomic groups (fish, daphnid, and green algae) were calculated to assess the ecological risk of DBPs, and the results demonstrated that both HAAs and HANs had high ecological risk for green algae in chlorinated wastewater effluents.

Molecularly imprinted solid phase extraction coupled with gas chromatography-mass spectrometry for determination of N-Nitrosodiphenylamine in water samples.

In this study, the molecularly imprinted polymers (MIPs) with high specific surface area and extraction efficiency of N-Nitrosodiphenylamine (NDPhA) were successfully prepared and a highly sensitive and selective method was developed for determination of NDPhA in water samples using MIPs solid-phase extraction (SPE) coupled with gas chromatography mass spectrometry (GC-MS) detection. The MIPs were successfully prepared using the method of precipitation polymerization and using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and N, N-Diphenylformamide as the template molecule. The newly synthesized MIPs were characterized and used as SPE sorbents. Under the optimized conditions, the average recoveries of NDPhA spiked in ultrapure water were higher than 94% ±â€¯2.9% at three different concentrations and the limit of detection and limit of quantitation were 0.8 ng L-1 and 2.4 ng L-1, respectively. Moreover, the high selectivity of MIPs was attained and the satisfactory recoveries of NDPhA which were spiked in to real samples were achieved in the range of 92-107% with relative standard deviations (RSDs) within 0.3-7.9%. The low levels of NDPhA were detected in the two of twelve wastewater samples with concentrations of 5.6 ng L-1 and 3.6 ng L-1 with RSDs of 5.6% and 2.8%, respectively. The developed MIP-SPE method was proved to be practically feasible for selective extraction and enrichment of NDPhA in real water samples.

Analysis of trace microcystins in vegetables using matrix solid-phase dispersion followed by high performance liquid chromatography triple-quadrupole mass spectrometry detection.

A selective and sensitive method for the simultaneous determination of five common microcystins (MC-LR, -RR, -YR, -LW, -LF) in various vegetables was established using Matrix Solid-Phase Dispersion (MSPD) followed by high performance liquid chromatography-mass spectrometry detection. To optimize the pretreatment procedure for extracting the microcystins from three vegetable matrices (tomato, cucumber and spinacia, which represented different colors), Box-Behnken design was employed to optimize the main factors affecting the extraction efficiency, including sample/dispersant mass ratio, as well as the proportion mixture dispersant and the volumes of solvent. Based on the optimum conditions, the intra-day and inter-day variability for each microcystins in all vegetable samples were less than 8.6%, with the recoveries ranging from 71.9% to 96.5%. The limits of detection and quantitation of the method were 13.0µg/kg (dw) and 43.0µg/kg (dw), respectively. The established method was successfully applied to the analysis of MCs in vegetable samples which were collected by Lake Taihu. The procedure promising to be relative small sample size and short pretreatment time for the assay that can be used for monitoring MCs concentrations in vegetables.

Using stable isotope labeling to study the nitrogen metabolism in Anabaena flos-aquae growth and anatoxin biosynthesis.

Freshwater resources are under stress around the world due to rapid urbanization and excessive water consumption. Cyanobacterial blooms have occurred frequently in surface waters, which produced toxic secondary metabolites causing a potential harm to aquatic ecosystems and humans. In this study, the relationship between different types of nitrogen source and the algal growth of Anabaena flos-aquae, which was isolated from Dianchi Lake in southern China, was investigated. Experiments were accomplished by using four types of isotope tracers including 15N-ammonium chloride, 15N-sodium nitrate, 15N-urea, 15N-l-alanine in culture medium to characterize the biosynthesis of 15N-anatoxin-a (ATX-A), which is a major algal toxin from A. flos-aquae, through liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results showed that all these four types of nitrogen can be incorporated into algal cells. The ATX-A production with urea as the nitrogen source was much higher than that with the other three types of nitrogen. The 15N labeling experiments further demonstrated that the uptake of organic nitrogen nutrients was significantly greater than that of inorganic nitrogen. These results provide new evidence and deeper insight to explore the biosynthesis of ATX-A in the specific strain of A. flos-aquae.