Sub-okra leaf shape conferred via chromosomal introgression from Gossypium barbadense L. improves photosynthetic productivity in short-season cotton (Gossypium hirsutum L.).

Leaf shape is a vital agronomic trait that affects plant and canopy architecture, yield, and other production attributes of upland cotton. Compared with normal leaves, lobed leaves have potential advantages in improving canopy structure and increasing cotton yield. A chromosomal introgression segment from Gossypium barbadense L. conferring sub-okra leaf shape to Gossypium hirsutum L. was identified on chromosome D01. To determine the effects of this transferred sub-okra leaf shape on the leaf anatomical characteristics, photosynthesis-related traits, and yield of short-season cotton, we performed a field experiment with three sets of near-isogenic lines carrying okra, sub-okra, and normal leaf shape in Lu54 (L54) and Shizao 2 (SZ2) backgrounds. Compared with normal leaves, sub-okra leaves exhibited reduced leaf thickness and smaller leaf mass per area; moreover, the deeper lobes of sub-okra leaves improved the plant canopy structure by decreasing leaf area index by 11.24%-22.84%. Similarly, the intercepted PAR rate of lines with sub-okra leaf shape was also reduced. The chlorophyll content of sub-okra leaves was lower than that of okra and normal leaf shapes; however, the net photosynthetic rate of sub-okra leaves was 8.17%-29.81% higher than that of other leaf shapes at most growth stages. Although the biomass of lines with sub-okra leaf shape was less than that of lines with normal leaves, the average first harvest yield and total yield of lines with the sub-okra leaf shape increased by 6.36% and 5.72%, respectively, compared with those with normal leaves. Thus, improvements in the canopy structure and photosynthetic and physiological characteristics contributed to optimizing the light environment, thereby increasing the yield of lines with sub-okra leaf shape. Our results suggest that the sub-okra leaf trait from G. barbadense L. may have practical applications for cultivating short-season varieties with high photosynthetic efficiency, and improving yield, which will be advantageous for short-season varieties.

Mixotrophic aerobic denitrification facilitated by denitrifying bacterial-fungal communities assisted with iron in micro-polluted water: Performance, metabolic activity, functional genes abundance, and community co-occurrence.

Low-dosage nitrate pollutants can contribute to eutrophication in surface water bodies, such as lakes and reservoirs. This study employed assembled denitrifying bacterial-fungal communities as bio-denitrifiers, in combination with zero-valent iron (ZVI), to treat micro-polluted water. Immobilized bacterial-fungal mixed communities (IBFMC) reactors demonstrated their ability to reduce nitrate and organic carbon by over 43.2 % and 53.7 %, respectively. Compared to IBFMC reactors, IBFMC combined with ZVI (IBFMC@ZVI) reactors exhibited enhanced removal efficiencies for nitrate and organic carbon, reaching the highest of 31.55 % and 17.66 %, respectively. The presence of ZVI in the IBFMC@ZVI reactors stimulated various aspects of microbial activity, including the metabolic processes, electron transfer system activities, abundance of functional genes and enzymes, and diversity and richness of microbial communities. The contents of adenosine triphosphate and electron transfer system activities enhanced more than 5.6 and 1.43 folds in the IBFMC@ZVI reactors compared with IBFMC reactors. Furthermore, significant improvement of crucial genes and enzyme denitrification chains was observed in the IBFMC@ZVI reactors. Iron played a central role in enhancing microbial diversity and activity, and promoting the supply, and transfer of inorganic electron donors. This study presents an innovative approach for applying denitrifying bacterial-fungal communities combined with iron enhancing efficient denitrification in micro-polluted water.

Menthol-Modified Quercetin Liposomes with Brain-Targeting Function for the Treatment of Senescent Alzheimer's Disease.

Oxidative stress and neuroinflammation in the aging brain are correlated with the development of neurodegenerative diseases, such as Alzheimer's disease (AD). The blood-brain barrier (BBB) poses a significant challenge to the effective delivery of therapeutics for AD. Prior research has demonstrated that menthol (Men) can augment the permeability of the BBB. Consequently, in the current study, we modified Men on the surface of liposomes to construct menthol-modified quercetin liposomes (Men-Qu-Lips), designed to cross the BBB and enhance quercetin (Qu) concentration in the brain for improved therapeutic efficacy. The experimental findings indicate that Men-Qu-Lips exhibited good encapsulation efficiency and stability, successfully crossed the BBB, improved oxidative stress and neuroinflammation in the brains of aged mice, protected neurons, and enhanced their learning and memory abilities.

Borneol-Modified Schisandrin B Micelles Cross the Blood-Brain Barrier To Treat Alzheimer's Disease in Aged Mice.

Objective: Schisandrin B (Sch B) is a bioactive dibenzocyclooctadiene derizative that is prevalent in the fruit of Schisandra chinensis. Numerous studies have demonstrated that Sch B has a neuroprotective action by reducing oxidative stress and effectively preventing inflammation. It follows that Sch B is a potential treatment for Alzheimer's disease (AD). However, the drug's solubility, bioavailability, and lower permeability of the blood-brain barrier (BBB) can all reduce its efficacy during the therapy process. Therefore, this study constructed borneol-modified schisandrin B micelles (Bor-Sch B-Ms), which increase brain targeting by accurately delivering medications to the brain, effectively improving bioavailability. High therapeutic efficacy has been achieved at the pathological site. Methods: Bor-Sch B-Ms were prepared using the thin film dispersion approach in this article. On the one hand, to observe the targeting effect of borneol, we constructed a blood-brain barrier (BBB) model in vitro and studied the ability of micelles to cross the BBB. On the other hand, the distribution of micelle drugs and their related pharmacological effects on neuroinflammation, oxidative stress, and neuronal damage were studied through in vivo administration in mice. Results: In vitro studies have demonstrated that the drug uptake of bEnd.3 cells was increased by the borneol alteration on the surface of the nano micelles, implying that Bor-Sch B-Ms can promote the therapeutic effect of N2a cells. This could result in more medicines entering the BBB. In addition, in vivo studies revealed that the distribution and circulation time of medications in the brain tissue were significantly higher than those in other groups, making it more suitable for the treatment of central nervous system diseases. Conclusion: As a novel nanodrug delivery system, borneol modified schisandrin B micelles have promising research prospects in the treatment of Alzheimer's disease.

Photosynthetic System Based on a Polyoxometalate-Based Dehydrated Metal-Organic Framework for Nitrogen Fixation.

In nature, biological nitrogen fixation is accomplished through the π-back-bonding mechanism of nitrogenase, which poses significant challenges for mimic artificial systems, thanks to the activation barrier associated with the N≡N bond. Consequently, this motivates us to develop efficient and reusable photocatalysts for artificial nitrogen fixation under mild conditions. We employ a charge-assisted self-assembly process toward encapsulating one polyoxometalate (POM) within a dehydrated Zr-based metal-organic framework (d-UiO-66) exhibiting nitrogen photofixation activities, thereby constructing an enzyme-mimicking photocatalyst. The dehydration of d-UiO-66 is favorable for facilitating nitrogen chemisorption and activation via the unpaired d-orbital electron at the [Zr6O6] cluster. The incorporation of POM guests enhanced the charge separation in the composites, thereby facilitating the transfer of photoexcited electrons into the π* antibonding orbital of chemisorbed N2 for efficient nitrogen fixation. Simultaneously, the catalytic efficiency of SiW9Fe3@d-UiO-66 is enhanced by 9.0 times compared to that of d-UiO-66. Moreover, SiW9Fe3@d-UiO-66 exhibits an apparent quantum efficiency (AQE) of 0.254% at 550 nm. The tactics of "working-in-tandem" achieved by POMs and d-UiO-66 are extremely vital for enhancing artificial ammonia synthesis. This study presents a paradigm for the development of an efficient artificial catalyst for nitrogen photofixation, aiming to mimic the process of biological nitrogen fixation.

Photochemical Ammonia Synthesis over Reduced Polyoxovanadate-Intercalated Defective ZnAl Layered Double Hydroxide Nanosheets.

The exploration of efficient and stable N2 fixation photocatalysts featuring a broad absorption spectrum and N2 fixation active sites has become specifically conspicuous. Herein, a series of reduced polyoxovanadates (POVs) were intercalated into copper-induced ZnAl layered double hydroxide (0.5%-ZnAl LDH) nanosheets with oxygen vacancies via an anion exchange strategy toward green ammonia production. The intervalence charge transfer arising from mixed-valence POV materials is responsible for its light-harvesting behavior, and the LDHs lay the foundation for the chemical adsorption and activation process of nitrogen molecules; both contributions facilitate the nitrogen photofixation performance of such composite materials. As predicted, the catalytic efficiency of V34/0.5%-ZnAl is 7.0 times higher than 0.5%-ZnAl LDH. Therefore, such an all-inorganic system exhibits an apparent quantum efficiency of 0.3137% at 500 nm. The strategy of "working in tandem" established by POV-based light-absorber species and oxygen vacancies as the sites for N2 activation is extremely vital for enhanced ammonia formation. This work opens up a versatile insight for the rational design of an efficient photo-driven nitrogen-reduction composite catalyst toward sustainable ammonia production compared to the industrial Haber-Bosch process.

Density and row spacing of short-season cotton suitable for machine picking in the cotton region of Yellow River Basin.

To determine the suitable planting density and row spacing of short-season cotton suitable for machine picking in the Yellow River Basin of China, we conducted a two-year field experiment in Dezhou during 2018-2019. The experiment followed a split-plot design, with planting density (82500 plants·hm-2 and 112500 plants·hm-2) as the main plots and row spacing (equal row spacing of 76 cm, wide-narrow row spacing of 66 cm+10 cm, equal row spacing of 60 cm) as the subplots. We examined the effects of planting density and row spacing on growth and development, canopy structure, seed cotton yield and fiber quality of short-season cotton. The results showed that plant height and LAI under high density treatment were significantly greater than those under low density treatment. The transmittance of the bottom layer was significantly lower than under low density treatment. Plant height under 76 cm equal row spacing was significantly higher than that under 60 cm equal row spacing, while that under wide-narrow row spacing (66 cm +10 cm) was significantly smaller than that under 60 cm equal row spacing in peak bolling stage. The effects of row spacing on LAI varied between the two years, densities, and growth stages. On the whole, the LAI under the wide-narrow row spacing (66 cm+10 cm) was higher, with the curve declining gently after the peak, and it was higher than that in the two cases of equal row spacing in the harvest time. The change in transmittance of the bottom layer presented the opposite trend. Density, row spacing, and their interaction had significant effects on seed cotton yield and its components. In both years, seed cotton yield was the highest (3832 kg·hm-2 in 2018, 3235 kg·hm-2 in 2019) under wide-narrow row spacing (66 cm+10 cm), and it was more stable at high densities. Fiber quality was less affected by density and row spacing. To sum up, the optimal density and row spacing of short-season cotton were as follows: density with 112500 plants·hm-2 and wide-narrow row spacing (66 cm+10 cm).

Plasmonic enhanced piezoelectric photoresponse with flexible PVDF@Ag-ZnO/Au composite nanofiber membranes.

The coordination of piezoelectric and plasmonic effects to regulate the separation and migration of photo-generated carriers is still a significant method to improve the performance of visible-light photoresponse. Herein, we propose the PVDF@Ag-ZnO/Au composite nanofiber membranes utilizing the piezoelectric and plasmonic effects to promote the photocatalytic degradation of organic dyes. Here, ZnO nanorods can generate a built-in electric field under vibration to separate electron-hole pairs. The Schottky junction formed by noble metal/semiconductor can not only inhibit the recombination of photo-generated carriers and accelerate the migration of carriers, but also enhance the utilization of visible light. In addition, the structure has excellent flexibility and easy recycling characteristics. We demonstrate that the plasmonic effect of noble metal can enhance the light response of membranes and broaden light absorption from ultraviolet to visible light region. With the help of the surface-enhanced Raman scattering (SERS), modulation effects of the piezoelectric effect on light response is proved. For catalytic processes, rhodamine B (98.8%) can be almost completely degraded using PVDF@Ag-ZnO/Au within 120 minutes in the piezoelectric photocatalysis process, which is 2.2 and 2.8 times higher than photocatalysis and piezoelectric catalysis, respectively. This work provides a promising strategy for harnessing solar and mechanical energy.

The Origin of Mo2C Films for Surface-Enhanced Raman Scattering Analysis: Electromagnetic or Chemical Enhancement?

The relatively weak Raman enhanced factors of semiconductor-based substrate limit its further application in surface-enhanced Raman scattering (SERS). Here, a kind of two-dimensional (2D) semimetal material, molybdenum carbide (Mo2C) film, is prepared via a chemical vapor deposition (CVD) method, and the origin of SERS is investigated for the first time. The detection limits of the prepared Mo2C films for crystal violet (CV) and rhodamine 6G (R6G) molecules are low at 10-6 M and 10-8 M, respectively. Our detailed theoretical analysis, based on density functional theory and the finite element method, demonstrates that the enhancement of the 2D Mo2C film is indeed CM in nature rather than the EM effects. Besides, the basic doping strategies are proposed to further optimize the SERS sensitivity of Mo2C for Fermi level regulation. We believe this work will provide a helpful guide for developing a highly sensitive semimetal SERS substrate.

Defected MoS2 Modified by Vanadium-Substituted Keggin-Type Polyoxometalates as Electrocatalysts for Triiodide Reduction in Dye-Sensitized Solar Cells.

The rational design of efficient triiodide reduction reaction catalysts that are dependent on cheap and ample elements on Earth has become a challenge. As an extremely encouraging non-noble metallic catalyst, MoS2 requires effective strategies to improve the site accessibility, inherent conductivity, and structural stability. Here, vanadium-substituted Keggin-type polyoxometalates (POMs) can be used as electron aggregates to modify manganese (Mn)-doped MoS2 through the electrochemical deposition strategy, thereby improving the charge transfer ability of MoS2 to I-/I3- redox pairs and accelerating the reduction of I3-. Additionally, with the increase in the number of vanadium atoms substituted in POMs, the conduction band of POMs and MoS2 can also match better, which effectively reduces the energy loss and is more conducive to charge transfer. Meanwhile, the deposition of POMs can improve the stability of metastable MoS2. When POMs/MoS2 materials are used as the counter electrodes of dye-sensitized solar cells, the power conversion efficiency (PCE) obtained is 7.27%, which is higher than that of platinum (Pt) (6.07%). The PCE can still maintain the initial 96% after 9 days. This work provides a valuable way for the improvement of platinum-free catalysts with minimal expense, basic process, high efficiency, and good stability.

Polyoxometalates-Based Semi-flexible Metal-Semiconductor Triboelectric Nanogenerators for Low Frequency and Small Amplitude Mechanical Energy Harvesting.

The development of high-performance and low-cost durable triboelectric nanogenerators (TENGs) is essential for converting mechanical energy into electrical energy. Many organic polymer friction materials used widely have thermal stability problems, which makes TENGs with semiconductors as friction materials stand out. Here, we report a semi-flexible TENG based on metal and TiO2 modified by polyoxometalates (POMs) as pure inorganic friction materials. Six different POMs are firstly selected to modify the friction materials of TENGs, and the output performance of TENGs with different POMs-modified semiconductors and different metals as friction materials are tested. Compared with the unmodified TENGs, the open-circuit voltage (VOC ) of the optimal Ag-K6 P2 Mo18 O62 (P2 Mo18 )/TiO2 TENG device is increased by more than 4 times, which is mainly attributed to the strong electron-accepting and storage capabilities of POMs. This study has demonstrated that TENGs modified by POMs have potential application prospects and provided a new method for increasing the electrical output of TENGs.

Heteropoly Blue/Protonation-Defective Graphitic Carbon Nitride Heterojunction for the Photo-Driven Nitrogen Reduction Reaction.

The establishment of a heterojunction is a crucial strategy to design highly effective nonnoble metal nanocatalysts for the photocatalytic nitrogen reduction reaction (PNRR). Heteropoly blues (r-POMs) can act as electron-transfer mediators in PNRR, but its agglomeration limits the further promotion of PNRR productivity. In this work, we construct a protonation-modified surface of N-vacancy g-C3N4 (HV-C3N4), achieving the high dispersion of r-POMs via the surface modification strategy. Enlightened by the synergy effect of the nitrogenase, r-POMs were anchored onto HV-C3N4 nanosheets through an electrostatic self-assembly method for preparing r-POMs-based protonation-defective graphitic carbonitride (HV-C3N4/r-POMs). As an electron donor, r-PW12 can match with the energy level of HV-C3N4 to build a heterojunction. The electron redistribution of the heterojunction facilitates the optimization of the electronic structure for enhancing the performance of PNRR. HV-C3N4/r-PW12 exhibits the best PNRR efficiency of 171.4 µmol L-1 h-1, which is boosted by 94.39% (HV-C3N4) and 86.98% (r-PW12). The isotope 15NH4+ experiment proves that ammonia is derived from N2, not carbon nitride. This study opens up a crucial view to achieve the high dispersion of r-POMs nanoparticles and develop high-efficiency nonnoble metal photocatalysts for the PNRR.

Astragaloside-IV regulates endoplasmic reticulum stress-mediated neuronal apoptosis in a murine model of Parkinson's disease via the lincRNA-p21/CHOP pathway.

OBJECTIVES: Astragaloside-IV (AS-IV) protects the nerve cells of Parkinson's disease (PD) from damage. Long non-coding RNA (lincRNA) has been found to be important for many diseases. Lincnra-p21 is abnormally expressed in PD. The purpose of this study was to investigate whether Astragaloside-IV (AS-IV) affects endoplasmic reticulum stress (ERS)-induced neuronal apoptosis in PD, and its possible mechanisms. METHODS: The PD mouse model was established via injecting 1-methyl-4-phenyl-1, 2, 3, 6- tetrahydropyridine (MPTP) and the PD cell model was established via inducing the MN9D cell line with 1-methyl-4-pehnyl-pyridine (MPP+). The behavioral testing of PD model mice was tested after AS-IV treatment and PD-related lincRNAs expression were detected by qRT-PCR. After treatment of PD model cells with AS-IV, lincRNA-p21 expression was detected by qRT-PCR, and cell viability and apoptosis were detected by MTT assay and flow cytometry, respectively. The binding of lincRNA-p21 to C/EBP-homologous (CHOP) protein was investigated by RNA immunoprecipitation and RNA pull-down, and the effect of lincRNA-p21 on the ubiquitination of CHOP protein was examined by ubiquitination assay. The role of lincRNA-p21 in PD model was studied by cell transfection. RESULTS: In PD mice, AS-IV can improve the behavior of mice and significantly inhibit expression of lincRNA-p21. Similarly, AS-IV can obviously restrain the expression of lincRNA-p21 in PD cells, and obviously elevated cell viability and restrained apoptosis. LincRNA-p21 is able to bind to CHOP protein. Further studies showed that restraint of lincRNA-p21 expression can facilitate ubiquitination of CHOP and accelerate its protein degradation. In AS-IV-treated PD model cells, overexpression of lincRNA-p21 lessened cell viability and facilitated apoptosis, whereas low expression of CHOP reversed this result. CONCLUSION: In this study, we found that AS-IV can lessen the expression of CHOP protein by restraining the expression of lincRNA-p21 in the PD model, thereby inhibiting neuronal apoptosis.

Secretogranin III upregulation is involved in parkinsonian toxin-mediated astroglia activation.

Environmental neurotoxins such as paraquat (PQ), manganese, and 1-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are associated with a higher risk of Parkinson's disease (PD). These parkinsonian toxins exert certain common toxicological effects on astroglia; however, their role in the regulatory functions of astroglial secretory proteins remains unclear. In a previous study, we observed that secretogranin II (SCG2) and secretogranin III (SCG3), which are important components of the regulated secretory pathway, were elevated in PQ-activated U118 astroglia. In the current study, we used the parkinsonian toxins dopamine (DA), active metabolite of MPTP (MPP+), MnCl2, and lipopolysaccharide (LPS) as inducers, and studied the potential regulation of SCG2 and SCG3. Our results showed that all the parkinsonian toxins except LPS affected astroglial viability but did not cause apoptosis. Exposure to DA, MPP+, and MnCl2 upregulated glial fibrillary acidic protein (GFAP), a marker for astrocyte activation, and stimulated the levels of several astrocytic-derived factors. Further, DA, MPP+, and MnCl2 exposure impeded astroglial cell cycle progression. Moreover, the expression of SCG3 was elevated, while its exosecretion was inhibited in astroglia activated by parkinsonian toxins. The level of SCG2 remained unchanged. In combination with our previous findings, the results of this study indicate that SCG3 may act as a cofactor in astrocyte activation stimulated by various toxins, and the regulation of SCG3 could be involved in the toxicological mechanism by which parkinsonian toxins affect astroglia.

Polyoxometalate-Derived Multi-Component X/W2 C@X,N-C (X=Co, Si, Ge, B, and P) Nanoelectrocatalysts for Efficient Triiodide Reduction in Dye-Sensitized Solar Cells.

Multi-component tungsten carbide-based hybrid materials featuring different heteroatom dopants coated with X,N dual-doped carbon layers (X/W2 C@X,N-C, XWXNC) were prepared by selecting Keggin-type polyoxometalates (POMs) (NH4 )n [XW12 O40 ] (X=Co, Si, Ge, B, and P) and dicyandiamide (DCA) as precursors. The electrocatalytic activity of these nanocomposites as counter electrode (CE) catalysts for dye-sensitized solar cells (DSSCs) was systematically investigated. Structure characterizations show that X,N heteroatoms were successfully introduced into the W2 C and carbon frameworks. The obtained X,N dual-doped carbon layers were modified and loaded with W2 C nanoparticles, promoting the improvement of catalytic performance by a synergistic effect. The consequence of photoelectric conversion efficiency (PCE) is CoWCoNC (6.68 %)>SiWSiNC (6.56 %)>GeWGeNC (6.49 %)>BWBNC (6.45 %)>PWPNC (6.20 %)>WNC (6.05 %). With the increase in electronegativity of the dopants, the photovoltaic performance decreases in a reverse order. This work provides a shortcut to the rational design of highly efficient and cost-effective catalysts for DSSCs.

Reduced State of the Graphene Oxide@Polyoxometalate Nanocatalyst Achieving High-Efficiency Nitrogen Fixation under Light Driving Conditions.

The nitrogen (N2) reduction to generate ammonia (NH3) is a prerequisite for inputting fixed nitrogen (N) into a global biogeochemical cycle. Developing highly efficient photocatalysts for N2 fixation under mild conditions is still a challenge. Herein, we first report three kinds of reduction states of graphene oxide (GO)@polyoxometalate (POM) composite nanomaterials, which have outstanding photocatalytic N2 fixation activities in pure water without any other electronic sacrificial agents and cocatalysts at atmospheric pressure and room temperature. A lot of experiments show that the remarkable photocatalytic N2 fixation performance of these three nanocatalysts is due to three factors that doping the reduced POMs (also called heteropoly blues) into the reduce GO (rGO) reduces the aggregation state of rGO (from 5 to 2 nm), resulting in rGO exposing many active sites to enhance the N2 adsorption amount, these three nanocatalysts possess a wide absorption spectrum and strong reducibility, which facilitate absorb light energy exciting abundant photoelectrons to activate N2, and rGO can effectively suppress the electrons recombination and rapidly transfer electrons to the absorbed N2 to accelerate NH3 production. Among them, r-GO@H5[PMo10V2O40] (PMo10V2) exhibits the highest NH3 generation efficiency of 130.3 µmol L-1 h-1, which is improved by 65.9 and 97.3% compared to the reduced PMo10V2 (rPMo10V2) and PMo10V2. Introduction of POMs provides a new perspective in the design of high-performance photocatalytic N2 fixation nanomaterials.

Abiotic and biotic controls on dynamics of labile phosphorus fractions in calcareous soils under agricultural cultivation.

Soil labile inorganic and organic phosphorus (L-Pi and L-Po) extracted by NaHCO3 are potentially important sources of plant-available P. Their availability is strongly affected by soil physiochemical and biological properties. Here we conducted a field study in an arid region of northwestern China to investigate how L-Pi and L-Po dynamics are affected by changes in physiochemical and biological variables caused by agricultural cultivation of calcareous soils. Topsoils were sampled at multiple sites from natural calcareous grasslands and cultivated farmlands of different ages (32-40 vs. 90-100 years) that had been converted from natural grasslands. We measured L-Pi and L-Po concentrations and a set of key physiochemical (soil pH, concentrations of base cations (K+ + Na+ + Ca2+ + Mg2+), acid anions (Cl- + NO3- + SO42-), nitrate and ammonium nitrogen (N), organic carbon, and total P) and biological (soil microbial biomass carbon (Cmic), alkaline phosphatase activity (Aalp), and abundances of soil macroinvertebrates (Amacro) and mesoinvertebrates (Ameso)) variables. The concentration of L-Pi and L-Po was 484% and 128% higher and their proportion in the total P content was 354% and 78% higher in young farmland soils, whereas L-Pi and L-Po concentrations were 583% and 423% higher and their proportions were 353% and 240% higher in old farmland soils compared to grassland soils. Increases in L-Pi and L-Po attributable to soil P release may be driven by crucial processes of soil acidification-induced phosphate dissolution and soil biota-driven Po mineralisation. Path analyses revealed that L-Pi and L-Po dynamics were shaped by the complex interactions among five key controlling factors, soil pH, nitrate-N, Ameso, Cmic, and Aalp, involved in these crucial processes. We conclude that cultivation of calcareous soils significantly increases the availability of L-Pi and L-Po, emphasizing the importance of this land-use change as a regulator of P cycling in calcareous soils.

Secretogranin III may be an indicator of paraquat-induced astrocyte activation and affects the recruitment of BDNF during this process.

Astrocyte activation has been described as a multi­stage defensive response, which is characterized by the morphological alteration of astrocytes and the overexpression of intermediate filament proteins. However, the functional mechanism of the secretion system in activated astroglia remains unclear. It has previously been demonstrated that secretogranin II, a member of the granin family, may be involved in the sorting and expression of inflammatory factors and excitatory neurotransmitters in paraquat (PQ)­induced astroglial activation. Secretogranin III (SCG3) has been reported to represent an important component of the regulated secretory pathway in neuroendocrine cells; however, its role as an anchor protein of dense­core vesicles in astrocytes remains to be elucidated. In the present study, a PQ­activated U118MG astrocytoma cell model established in our previous study was used to investigate the effects of SCG3. The results revealed that SCG3 was highly expressed and subsequently released from cells in response to PQ. Inhibition of SCG3 expression via transfection with small interfering RNA partially restored astrocyte morphology, but did not affect the expression of astrocytic factors. Further studies investigating the association between SCG3 and other cellular factors were conducted, in order to determine the expression levels and subcellular localization of these proteins. Neurotrophins and inflammatory factors exhibited an increase in characteristic expression patterns, paralleling the alterations in SCG3 expression. The results further demonstrated that brain­derived neurotrophic factor partially colocalized with SCG3­positive vesicles; however, the localization of interleukin­6 was not affected. In conclusion, SCG3 may be involved in PQ­induced astrocyte activation via regulation of the expression and selective recruitment of cellular factors, thus suggesting that SCG3 may represent an indicator of astrocyte activation.

Effects of PQ's cytotoxicity on secretory vesicles in astroglia: Expression alternation of secretogranin II and its potential interaction with intracellular factors.

It has been extensively characterized that paraquat (PQ) selectively targets to the substantia nigra and exerts neurotoxic actions on dopaminergic neurons. However, a little knowledge is available about astroglia in PQ exposure, especially its complex secretory machinery. To explore this point, we built up a PQ-induced model in cultural U118 astrocyte. Since the granin family is considered as a master regulator of cargo sorting and large dense core vesicles (LDCVs) biogenesis in the regulated secretory pathway of nervous and neuroendocrine cells, the current study focused on one member, secretogranin II (SCG2) and investigated its alternation and potential relationship with other astrocyte-derived factors under PQ insult. We found that PQ upregulated SCG2 expression on both RNA and protein levels and stimulated the mRNA expression of neurotrophic factors, cytokines and glutamine synthetase (GS) simultaneously. RNAi knockdown of SCG2 did not rescue the cell cycle arrest induced by PQ but affected expressions of IL-6 and GS on mRNA and protein levels. Further studies on subcellular location showed that SCG2-positive secretory granules were partially colocalized with IL-6 but not GS in PQ exposure astrocyte. Taken together, our findings indicate that the expression alternation of SCG2 under astroglial activation by PQ may be necessary compensation for cargo sorting and LDCV biogenesis. The involvement of the IL-6 and GS suggests that the SCG2 may potentially regulate inflammatory factors and excitatory neurotransmitter to the cytotoxicity of PQ on astroglia.