The Performance and Evolutionary Mechanism of Ganoderma lucidum in Enhancing Selenite Tolerance and Bioaccumulation.

BACKGROUND: Selenium (Se) pollution poses serious threats to terrestrial ecosystems. Mushrooms are important sources of Se with the potential for bioremediation. Pre-eminent Se resources must possess the ability to tolerate high levels of Se. To obtain Se-accumulating fungi, we isolated selenite-tolerance-enhanced Ganoderma lucidum JNUSE-200 through adaptive evolution. METHODS: The molecular mechanism responsible for selenite tolerance and accumulation was explored in G. lucidum JNUSE-200 by comparing it with the original strain, G. lucidum CGMCC 5.26, using a combination of physiological and transcriptomic approaches. RESULTS: G. lucidum JNUSE-200 demonstrated tolerance to 200 mg/kg selenite in liquid culture and exhibited normal growth, whereas G. lucidum CGMCC 5.26 experienced reduced growth, red coloration, and an unpleasant odor as a result of exposure to selenite at the same concentration. In this study, G. lucidum JNUSE-200 developed a triple defense mechanism against high-level selenite toxicity, and the key genes responsible for improved selenite tolerance were identified. CONCLUSIONS: The present study offers novel insights into the molecular responses of fungi towards selenite, providing theoretical guidance for the breeding and cultivation of Se-accumulating varieties. Moreover, it significantly enhances the capacity of the bio-manufacturing industry and contributes to the development of beneficial applications in environmental biotechnology through fungal selenite transformation bioprocesses.

Enzymatic mechanism of MlrB for catalyzing linearized microcystins by Sphingopyxis sp. USTB-05.

Microcystins (MCs) are the most widespread cyanobacterial toxins in eutrophic water body. As high toxic intermediate metabolites, linearized MCs are further catalyzed by linearized microcystinase (MlrB) of Sphingopyxis sp. USTB-05. Here MlrB structure was studied by comprizing with a model representative of the penicillin-recognizing enzyme family via homology modeling. The key active sites of MlrB were predicted by molecular docking, and further verified by site-directed mutagenesis. A comprehensive enzymatic mechanism for linearized MCs biodegradation by MlrB was proposed: S77 transferred a proton to H307 to promote a nucleophilic attack on the peptide bond (Ala-Leu in MC-LR or Ala-Arg in MC-RR) of linearized MCs to form the amide intermediate. Then water was involved to break the peptide bond and produced the tetrapeptide as product. Meanwhile, four amino acid residues (K80, Y171, N173 and D245) acted synergistically to stabilize the substrate and intermediate transition states. This study firstly revealed the enzymatic mechanism of MlrB for biodegrading linearized MCs with both computer simulation and experimental verification.

Zero-Velocity Update-Based GNSS/IMU Tightly Coupled Algorithm with the Constraint of the Earth's Rotation Angular Velocity for Cableway Bracket Deformation Monitoring.

Cableways have been widely used in industrial areas, cities, and scenic spots due to their advantages, such as being a convenient mode of transportation, time-saving, labor-saving, and low cost, as well as offering environmental protection. To ensure the safe operation of a cableway, based on the characteristic that the velocity of the cableway bracket is approximately zero in a static deformation monitoring environment, a deformation monitoring method called zero velocity update (ZUPT)-based GNSS/IMU tightly coupled algorithm with the constraint of the Earth's rotation angular velocity was proposed. The proposed method can effectively solve the problem of a single GNSS being unable to output attitude, which is directly related to the status of wire ropes and cable cars. Meanwhile, ZUPT is used to restrain the Kalman filter's divergence when IMU is stationary. However, the improvements of ZUPT on attitude are not obvious, so the constraint of the Earth's rotation angular velocity was applied. The performance of the proposed method was evaluated through monitoring the cableway bracket of the Yimeng Mountain Tourism area in Shandong. Compared with the ZUPT-based GNSS/IMU tightly coupled algorithm (ZUPT-TC), the proposed method can further constrain the error accumulation of IMU while stationary and, therefore, it can provide reliable position and attitude information on cableway brackets.

A novel proxy to examine interspecific phosphorus facilitation between plant species.

Resource complementarity can contribute to enhanced ecosystem functioning in diverse plant communities, but the role of facilitation in the enhanced complementarity is poorly understood. Here, we use leaf manganese concentration ([Mn]) as a proxy for rhizosheath carboxylate concentration to explore novel mechanisms of complementarity mediated by phosphorus (P) facilitation. In pot experiments, we showed that mixtures involving Carex korshinskyi, an efficient P-mobilizing species, exhibited greater biomass and relative complementarity effect than combinations without C. korshinskyi on P-deficient soils. Compared with monocultures, leaf [Mn] and [P] of species that are inefficient at P mobilization increased by 27% and 21% when grown with C. korshinskyi (i.e. interspecific P facilitation via carboxylates) rather than next to another inefficient P-mobilizing species. This experimental result was supported by a meta-analysis including a range of efficient P-mobilizing species. Phosphorus facilitation enhanced the relative complementarity effect in low-P environments, related to a greater change in several facilitated species of their root morphological traits relative to those in monoculture. Using leaf [Mn] as a proxy, we highlight a vital mechanism of interspecific P facilitation via belowground processes and provide evidence for the pivotal role of P facilitation mediated by the plasticity of root traits in biodiversity research.

Effects of Different Drying Methods on the Selenium Bioaccessibility and Antioxidant Activity of Cardamine violifolia.

Understanding the effects of drying on the selenium (Se) content and Se bioaccessibility of Se-rich plants is critical to dietary supplementation of Se. The effects of five common drying methods (far-infrared drying (FIRD), vacuum drying (VD), microwave vacuum drying (MVD), hot air drying (HD), and freeze vacuum drying (FD)) on the content and bioaccessibility of Se and Se species in Cardamine violifolia leaves (CVLs) were studied. The content of SeCys2 in fresh CVLs was the highest (5060.50 µg/g of dry weight (DW)); after FIRD, it had the lowest selenium loss, with a loss rate of less than 19%. Among all of the drying processes, FD and VD samples had the lowest Se retention and bioaccessibility. FIRD, VD, and FD samples have similar effects on antioxidant activity.

Plant litter strengthens positive biodiversity-ecosystem functioning relationships over time.

Plant biodiversity-productivity relationships become stronger over time in grasslands, forests, and agroecosystems. Plant shoot and root litter is important in mediating these positive relationships, yet the functional role of plant litter remains overlooked in long-term experiments. We propose that plant litter strengthens biodiversity-ecosystem functioning relationships over time in four ways by providing decomposing detritus that releases nitrogen (N) over time for uptake by existing and succeeding plants, enhancing overall soil fertility, changing soil community composition, and reducing the impact of residue-borne pathogens and pests. We bring new insights into how diversity-productivity relationships may change over time and suggest that the diversification of crop residue retention through increased residue diversity from plant mixtures will improve the sustainability of food production systems.

Effects of zinc and iron on the abundance of Microcystis in Lake Taihu under green light and turbulence conditions.

Trace element is one of the important factors affecting the growth of Microcystis. The effects of zinc (0.4 mg/L) and iron (2 mg/L) on the abundance of Microcystis in Lake Taihu were investigated under continuous turbulence and green light conditions in a microcosm experiment. The study results showed that the abundance of Microcystis in the zinc treatment and the iron treatment group was 8.30% and 214% of that in the control group at the end of the experiment, respectively. The proportion of Cyanobacteria in the total phytoplankton biomass in the control, iron treatment, and zinc treatment group decreased from 99.99% at the beginning of the experiment to 13%, 18%, and 1% at the end of the experiment, respectively. At the end of the microcosm experiment, the phytoplankton community was dominated by Bacillariophyta in the control group, accounting for 63%, but it was dominated by Chlorophyta in the zinc treatment and the iron treatment group, accounting for 89% and 42%, respectively. The study results showed that under green light and turbulence, 0.4 mg/L zinc remarkably decreased the abundance of Microcystis, but 2 mg/L iron effectively increased the number of Microcystis and other algae. This research results provided a new idea for controlling Microcystis blooms.

Continuous hydrodynamic mixing weakens the dominance of Microcystis: evidences from microcosm and lab experiments.

Hydrodynamic mixing is one of the important environment factors in determining phytoplankton community compositions. Here the influences of continuous hydrodynamic mixing on abundance, morphology, and dominance of Microcystis were investigated in microcosm and lab experiments. Our research results showed that Cyanophyta contributed 57.16% to the total biomass in control, but Chlorophyta was the dominant group in continuous hydrodynamic mixing (CHM) group, contributing 76.54% to the total biomass in the microcosm experiment. The average number of Microcystis in control was 1.95 folds in CHM group. However, the mean abundance of Scenedesmus quadricauda and Pseudanabaena limnetica in CHM was 2.47 and 2.97 folds in control. In the lab experiment, the average number of Microcystis flos-aquae in control was 2.97 folds in CHM group. The mean size of M. flos-aquae colony in control (34.65 µm) group were significantly bigger than that in the CHM (26.78 µm) group. This research results demonstrated that continuous hydrodynamic mixing weakened the dominance of Microcystis, but was beneficial for the others algae (S. quadricauda and P. limnetica) and is helpful in understanding the effect of hydrodynamic mixing on Microcystis blooms in freshwater ecosystem.

Belowground facilitation and trait matching: two or three to tango?

High biodiversity increases ecosystem functions; however, belowground facilitation remains poorly understood in this context. Here, we explore mechanisms that operate via 'giving-receiving feedbacks' for belowground facilitation. These include direct effects via root exudates, signals, and root trait plasticity, and indirect biotic facilitation via the effects of root exudates on soil biota and feedback from biota to plants. We then highlight that these two- or three-way mechanisms must affect biodiversity-ecosystem function relationships via specific combinations of matching traits. To tango requires a powerful affinity and harmony between well-matched partners, and such matches link belowground facilitation to the effect of biodiversity on function. Such matching underpins applications in intercropping, forestry, and pasture systems, in which diversity contributes to greater productivity and sustainability.

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter.

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the ROx (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%-150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%-50% enhancements in the areas around 35-40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.

Phosphorus facilitation and covariation of root traits in steppe species.

Different phosphorus (P)-acquisition strategies may be relevant for species coexistence and plant performance in terrestrial communities on P-deficient soils. However, how interspecific P facilitation functions in natural systems is largely unknown. We investigated the root physiological activities for P mobilization across 19 coexisting plant species in steppe vegetation, and then grew plants with various abilities to mobilize sorbed P in a microcosm in a glasshouse. We show that P facilitation mediated by rhizosphere processes of P-mobilizing species promoted growth and increased P content of neighbors in a species-specific manner. When roots interacted with a facilitating neighbor, Cleistogenes squarrosa and Bromus inermis tended to show greater plasticity of root proliferation or rhizosheath acid phosphatase activity compared with other non-P-mobilizing species. Greater variation in these root traits was strongly correlated with increased performance in the presence of a facilitator. The results also show, for the first time, that P facilitation was an important mechanism underlying a positive complementarity effect. Our study highlights that interspecific P-acquisition facilitation requires that facilitated neighbors exhibit a better match of root traits with a facilitating species. It provides a better understanding of species coexistence in P-limited communities.

Linking shifts in species composition induced by grazing with root traits for phosphorus acquisition in a typical steppe in Inner Mongolia.

Long-term overgrazing tends to cause soil phosphorus (P) deficiency in grasslands. The relationships between grazing-induced shifts in species composition and root traits associated with P acquisition involved in these shifts remain unknown. Species vary in their P-acquisition strategies, and we hypothesize that species that acquire P more efficiently are better adapted to overgrazing. We measured relative biomass, root physiological activities (e.g., rhizosheath acid phosphatase activity (Apase), and leaf manganese concentration ([Mn]) as a proxy for carboxylate concentrations in rhizosheath) and morphological traits (e.g., specific root length) of six common species in a field experiment conducted in a typical steppe of Inner Mongolia. There were two exclosure demonstration plots, i.e. exclosed since 1983 and 1996, and long-term free grazing without exclosure of sheep. Long-term overgrazing caused a reduction in bulk soil Olsen P concentration and increased community-weighted leaf nitrogen: P ratio by 27% and 37%, respectively, indicating more severe P limitation for steppe vegetation. Carex duriuscula exhibited an inherently greater specific root length, proportion of fine roots and rhizosheath Apase than other species did in both exclosure and grazing treatments. Cleistogenes squarrosa showed a greater leaf [Mn] induced by overgrazing. The increased dominance of C. duriuscula and C. squarrosa was positively correlated with finer roots, greater rhizosheath Apase or carboxylate release under long-term overgrazing. Species that had inefficient root traits for P acquisition (e.g., low specific root length and low leaf [Mn]), i.e. Stipa grandis, exhibited a decreased dominance in response to overgrazing. Dominance of species did not change under grazing which may be related to either relatively inefficient inherent morphological (i.e. in Artemisia frigida) or physiological traits (i.e. in Leymus chinensis and Agropyron michnoi) for P acquisition. Our study highlights the importance of acknowledging root traits involved in efficient P acquisition for theories on community succession induced by overgrazing.

Dietary supplementation with probiotics regulates gut microbiota structure and function in Nile tilapia exposed to aluminum.

BACKGROUNDS AND AIMS: Aluminum contamination of water is becoming increasingly serious and threatens the health status of fish. Lactobacillus plantarum CCFM639 was previously shown to be a potential probiotic for alleviation aluminum toxicity in Nile tilapia. Considering the significant role of the gut microbiota on fish health, it seems appropriate to explore the relationships among aluminum exposure, probiotic supplementation, and the gut microbiota in Nile tilapia and to determine whether regulation of the gut microbiota is related to alleviation of aluminum toxicity by a probiotic in Nile tilapia. METHODS AND RESULTS: The tilapia were assigned into four groups, control, CCFM639 only, aluminum only, and aluminum + CCFM639 groups for an experimental period of 4 weeks. The tilapia in the aluminum only group were grown in water with an aluminum ion concentration of 2.73 mg/L. The final concentration of CCFM639 in the diet was 108 CFU/g. The results show that environmental aluminum exposure reduced the numbers of L. plantarum in tilapia feces and altered the gut microbiota. As the predominant bacterial phyla in the gut, the abundances of Bacteroidetes and Proteobacteria in aluminum-exposed fish were significantly elevated and lowered, respectively. At the genus level, fish exposed to aluminum had a significantly lower abundance of Deefgea, Plesiomonas, and Pseudomonas and a greater abundance of Flavobacterium, Enterovibrio, Porphyromonadaceae uncultured, and Comamonadaceae. When tilapia were exposed to aluminum, the administration of a probiotic promoted aluminum excretion through the feces and led to a decrease in the abundance of Comamonadaceae, Enterovibrio and Porphyromonadaceae. Notably, supplementation with a probiotic only greatly decreased the abundance of Aeromonas and Pseudomonas. CONCLUSION: Aluminum exposure altered the diversity of the gut microbiota in Nile tilapia, and probiotic supplementation allowed the recovery of some of the diversity. Therefore, regulation of gut microbiota with a probiotic is a possible mechanism for the alleviation of aluminum toxicity in Nile tilapia.

Triptolide inhibits the inflammatory activities of neutrophils to ameliorate chronic arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by cellular infiltration into the joints and cartilage destruction. Neutrophils play a crucial role in the pathogenesis of RA. Triptolide (TP) is a bioactive compound derived from Tripterygium wilfordii Hook F, which has been used in folk medicine as a treatment for a variety of inflammatory disorders, including RA, for many centuries. Previous studies have shown that TP possesses anti-arthritic activity. However, the anti-arthritic mechanism of TP remains to be fully defined. In the present study, we used the adjuvant-induced arthritis (AA) murine model of RA to investigate the impact of TP on RA and neutrophil function. TP alleviated AA by reducing neutrophil recruitment and suppressing the expression of interleukin-6 and tumour necrosis factor-α in vivo. TP also suppressed the expression of pro-inflammatory cytokines in neutrophils, promoted neutrophil apoptosis and inhibited the migration, NETosis and autophagy of neutrophils in vitro. Based on our findings, TP effectively ameliorates RA by down-regulating neutrophil inflammatory functions, indicating that TP represents a potential therapeutic agent for RA.

Au nanoflower-Ag nanoparticle assembled SERS-active substrates for sensitive MC-LR detection.

Surface-enhanced Raman scattering (SERS)-active substrates assembled by two types of metallic nanoparticles (NPs) were fabricated. Aptamers driven Au nanoflower (Au NF)-Ag NP core-satellite assemblies exhibited amplified SERS signals and achieved the sensitive detection of microcystin-LR (MC-LR) in Tai lake water with the limit of detection (LOD) of 8.6 ± 0.4 pM.

[Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography].

A method based on accelerated solvent extraction-ion chromatography (ASE-IC) was developed for the simultaneous determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in plastic samples. The accelerated solvent extraction was employed as the pretreatment method for the simultaneous extraction of the Cr(III) and Cr(VI) from the samples. Cr(III) and Cr(VI) were derivatized with 2,6-pyridinedicarboxylic acid (PDCA) and 1,5-diphenyl-carbazide (DPC), and detected by an ultraviolet-visible (UV-Vis) detector at UV and visible wavelengths, respectively. The results showed that the limits of detection for Cr(III) and Cr(VI) were 5.0 microg/L and 0.5 microg/L and the good linearities of the calibration curves for them were in the ranges of 50 - 1 000 microg/L (r2 = 0.9994) and 5.0 - 100 microg/L (r2 = 0.9998), respectively. The recoveries were between 90.7% and 101.1% with the relative standard deviations (RSDs) of 1.7% -4.4% for Cr(III) and Cr(VI). The method is sensitive, reproducible and adaptable to the simultaneous determination of Cr(III) and Cr(VI) in the plastic samples.

[Analysis and comparison of trace elements of herba euphorbiae humifusae in different periods by microwave digestion-atomic absorption spectroscopy].

Herba euphorbiae humifusae is the dried whole plant of Euphorbia humi fusa Willd. that belongs to euphorbiaceae. In the present paper, the microwave digestion procedure was used to digest herba euphorbiae humifusae collected in different periods, and then flame atomic absorption spectrometry (FAAS) was used to determine the contents of eight kinds of trace elements of herba euphorbiae humifusae in different periods, and the change in the contents of trace elements at different times was studied and analysed. The results showed that of all the trace elements of herba euphorbiae humifusae in different periods, element Fe was the highest in June, element K was in August at the highest level, element Mn reached the highest content in September, elements Na and Ca were dividedly at the highest content in October and November, and in December the highest content elements were Zn, Cu and Mg. In one word, the change of Na and Ca was jumping, while the change of Cu and Zn was comparatively mild. The results provide scientific basis for the time of collection of herba euphorbiae humifusae.

[Determination of trace elements in radix Paeoniae alba by microwave digestion-ICP-AES].

Microwave digestion technique was used in the decomposition of radix Paeoniae alba samples of different growing area, different growing time and before and after processing, and the contents of K, Ca, Na, Mg, Zn and Fe were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results of the determination show that radix Paeoniae alba samples are rich in the trace elements. The RSDs of these elements were lower than 4%, and the recovery ratio ranged between 99% and 113%. The results revealed that the analytic method is sensitive and precise. The pattern recognition based on the principal component analysis (PCA) was applied to the measured trace elements of different radix Paeoniae alba samples. The PCA was useful in the classification of radix Paeoniae alba. This paper provides scientific basis for deeply studying the relation between the trace elements and the drug effect of radix Paeoniae alba.

[Study on the absorption and fluorescence spectra of ethylene glycol and glycerol].

The absorption and fluorescence spectra of ethylene glycol and glycerol solution induced by UV light were studied respectively in the present paper. The most intense absorption wavelength for both of them was located at 198 nm. Moreover, fluorescence was detected when induced by suitable UV light, and the corresponding fluorescence spectra were listed. But there is no obvious relationship found between the fluorescence intensity and the excited wavelength, and a further research should be done. From the first derivative fluorescence spectra of ethylene glycol, it was concluded that under the UV light of 210 nm, the variation speed for relative intensity proved to be the fastest. In contrast, when excited by 225 nm, the speed proved to be the slowest. In addition, based on the quantum calculation and the transition from HOMO to LUMO of electronics in one-dimensional quantum well, the authors attempted to give out the value of absorption wavelength. In consideration of the bond-length variety brought out by the chain processing, the error between the experimental and calculation values should be apprehensible, and the latter can serve as some reference value in theory.

[Determination and comparison of trace elements in four sorts of Bulbus Fritillariae by microwave digestion-atomic absorption spectrometry].

The contents of elements such as Zn, Fe, Mn, Cu, Na, Mg, K, Ca, As, Pb, Cd, Co, Cr, Sr, and Al in four sorts of Bulbus Fritillariae, namaly from Fritillaria thunbergii Miq. (Panan and Ningbo), Fritillaria thunbergii Miq. Var. chekiangensis Hsiao et K. C. Hsia and Fritillaria cirrhosa D. Don, were determined by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) respectively. The effect of different microwave digestion conditions on the analysis results was reviewed, and optimal condition for using atomic absorption spectrophotometry was determined. Principal component analysis (PCA) was applied taking trace elements contents as indexes. The results revealed that microwave digestion was a simple, rapid, digestion complete, and low blank value method, and the measurement result is satisfactory. The experimental results indicated that the linear relationships for different elements within the limits of working curve were good. The RSDs were all smaller than 3.97%. The addition standard rates of the procedure was between 91.0% and 108.7%. Principal component analysis has the application value of reflecting the differences in trace elements contents in various samples.