Elucidating the intricacies of the H2S signaling pathway in gasotransmitters: Highlighting the regulation of plant thiocyanate detoxification pathways.

In recent decades, there has been increasing interest in elucidating the role of sulfur-containing compounds in plant metabolism, particularly emphasizing their function as signaling molecules. Among these, thiocyanate (SCN-), a compound imbued with sulfur and nitrogen, has emerged as a significant environmental contaminant frequently detected in irrigation water. This compound is known for its potential to adversely impact plant growth and agricultural yield. Although adopting exogenous SCN- as a nitrogen source in plant cells has been the subject of thorough investigation, the fate of sulfur resulting from the assimilation of exogenous SCN- has not been fully explored. There is burgeoning curiosity in probing the fate of SCN- within plant systems, especially considering the possible generation of the gaseous signaling molecule, hydrogen sulfide (H2S) during the metabolism of SCN-. Notably, the endogenous synthesis of H2S occurs predominantly within chloroplasts, the cytosol, and mitochondria. In contrast, the production of H2S following the assimilation of exogenous SCN- is explicitly confined to chloroplasts and mitochondria. This phenomenon indicates complex interplay and communication among various subcellular organelles, influencing signal transduction and other vital physiological processes. This review, augmented by a small-scale experimental study, endeavors to provide insights into the functional characteristics of H2S signaling in plants subjected to SCN--stress. Furthermore, a comparative analysis of the occurrence and trajectory of endogenous H2S and H2S derived from SCN--assimilation within plant organisms was performed, providing a focused lens for a comprehensive examination of the multifaceted roles of H2S in rice plants. By delving into these dimensions, our objective is to enhance the understanding of the regulatory mechanisms employed by the gasotransmitter H2S in plant adaptations and responses to SCN--stress, yielding invaluable insights into strategies for plant resilience and adaptive capabilities.

Integrated physiological and transcriptomic analyzes reveal the duality of TiO2 nanoparticles on alfalfa (Medicago sativa L.).

Alfalfa (Medicago sativa L.) is a feed crop due to its rich nutrition and high productivity. The utilization of titanium oxide nanoparticles (TiO2 NPs) brings benefits to agricultural production but also has potential hazards. To investigate the duality and related mechanism of TiO2 NPs on alfalfa, its different doses including 0, 50, 100, 200, 500, and 1000 mg L- 1 (CK, Ti-50, Ti-100, Ti-200, Ti-500, and Ti-1000) were sprayed on leaves. The results showed that greater doses of TiO2 NPs (500 and 1000 mg L-1) negatively affected the physiological parameters, including morphology, biomass, leaf ultrastructure, stomata, photosynthesis, pigments, and antioxidant ability. However, 100 mg L-1 TiO2 NPs revealed an optimal positive effect; compared with the CK, it dramatically increased plant height, fresh weight, and dry weight by 22%, 21%, and 41%, respectively. Additionally, TiO2 NPs at low doses significantly protected leaf tissue, promoted stomatal opening, and enhanced the antioxidant system; while higher doses had phytotoxicity. Hence, TiO2 NPs are dose-dependent on alfalfa. The transcriptomic analysis identified 4625 and 2121 differentially expressed genes (DEGs) in the comparison of CK vs. Ti-100 and CK vs. Ti-500, respectively. They were mainly enriched in photosynthesis, chlorophyll metabolism, and energy metabolism. Notably, TiO2 NPs-induced phytotoxicity on photosynthetic parameters happened concurrently with the alterations of the genes involved in the porphyrin and chlorophyll metabolism and carbon fixation in photosynthetic organisms in the KEGG analysis. Similarly, it affected the efficiency of alfalfa energy transformation processes, including pyruvate metabolism and chlorophyll synthesis. Several key related genes in these pathways were validated. Therefore, TiO2 NPs have positive and toxic effects by regulating morphology, leaf ultrastructure, stomata, photosynthesis, redox homeostasis, and genes related to key pathways. It is significant to understand the duality of TiO2 NPs and cultivate varieties resistant to nanomaterial pollution.

Differences in junction-associated gene expression changes in three rat models of diabetic retinopathy with similar neurovascular phenotype.

Diabetic retinopathy, also defined as microvascular complication of diabetes mellitus, affects the entire neurovascular unit with specific aberrations in every compartment. Neurodegeneration, glial activation and vasoregression are observed consistently in models of diabetic retinopathy. However, the order and the severity of these aberrations varies in different models, which is also true in patients. In this study, we analysed rat models of diabetic retinopathy with similar phenotypes to identify key differences in the pathogenesis. For this, we focussed on intercellular junction-associated gene expression, which are important for the communication and homeostasis within the neurovascular unit. Streptozotocin-injected diabetic Wistar rats, methylglyoxal supplemented Wistar rats and polycystin-2 transgenic (PKD) rats were analysed for neuroretinal function, vasoregression and retinal expression of junction-associated proteins. In all three models, neuroretinal impairment and vasoregression were observed, but gene expression profiling of junction-associated proteins demonstrated nearly no overlap between the three models. However, the differently expressed genes were from the main classes of claudins, connexins and integrins in all models. Changes in Rcor1 expression in diabetic rats and Egr1 expression in PKD rats confirmed the differences in upstream transcription factor level between the models. In PKD rats, a possible role for miRNA regulation was observed, indicated by an upregulation of miR-26b-5p, miR-122-5p and miR-300-3p, which was not observed in the other models. In silico allocation of connexins revealed not only differences in regulated subtypes, but also in affected retinal cell types, as well as connexin specific upstream regulators Sox7 and miR-92a-3p. In this study, we demonstrate that, despite their similar phenotype, models for diabetic retinopathy exhibit significant differences in their pathogenic pathways and primarily affected cell types. These results underline the importance for more sensitive diagnostic tools to identify pathogenic clusters in patients as the next step towards a desperately needed personalized therapy.

Sufficient Cav-1 levels in the endothelium are critical for the maintenance of the neurovascular unit in the retina.

BACKGROUND: Caveolin-1 (Cav-1) is a pivotal protein in the plasma membrane. Studies on homozygous Cav-1 deficient mice revealed that Cav-1 is essential for endothelial function and angiogenesis in the retina. However, whether a reduction in Cav-1 content hampers the neurovascular unit (NVU) in the retina is unclear. Thus, this study examines the NVU in the retinas of heterozygous Cav-1 deficient (Cav-1+/-) mice and analyzes possible underlying mechanisms. METHODS: The vascular, glial and neuronal components in the retina were evaluated using retinal morphometry, whole mount retinal immunofluorescence staining, histological analysis and optical coherence tomography. In addition, immunoblotting and immunofluorescence staining, subcellular fractionation, biotin labeling of cell surface proteins, and proximity ligation assay were employed to detect expression and localization of proteins in the retina or endothelial cells (ECs) upon knockdown of Cav-1 with Cav-1 siRNA. RESULTS: Cav-1+/- retinas showed a significant reduction in pericyte coverage along with an increase in acellular capillaries compared to controls at 8 months of age, but not at 1 month. A significant loss and obvious morphological abnormalities of smooth muscle cells were observed in 8-month-old Cav-1+/- retinal arterioles. Macroglial and microglial cells were activated in the Cav-1+/- retinas. A transient significant delay in retinal angiogenesis was detected in Cav-1+/- retinas at p5, which was however no longer detectable at p10. The Cav-1+/- retinas displayed increased vascular permeability and a notable reduction in VEGFR2 content at 8 months. In vitro, siRNA-mediated knockdown experiments in ECs revealed that the loss of Cav-1 in ECs resulted in decreased levels of VEGFR2, VE-Cadherin and their interaction at the plasma membrane as well. CONCLUSION: Our results indicate that a sufficient Cav-1 level over 50% of its normal abundance is vital for the proper localization of VEGFR2 and VE-cadherin, likely in a complex, at the plasma membrane, which is essential for the maintenance of normal NVU in the retina.

Chemical Tools for Studying Phosphohistidine: Generation of Selective τ-Phosphohistidine and π-Phosphohistidine Antibodies.

Nonhydrolysable stable analogues of τ-phosphohistidine (τ-pHis) and π-pHis have been designed, aided by electrostatic surface potential calculations, and subsequently synthesized. The τ-pHis and π-pHis analogues (phosphopyrazole 8 and pyridyl amino amide 13, respectively) were used as haptens to generate pHis polyclonal antibodies. Both τ-pHis and π-pHis conjugates in the form of BSA-glutaraldehyde-τ-pHis and BSA-glutaraldehyde-π-pHis were synthesized and characterized by 31 P NMR spectroscopy. Commercially available τ-pHis (SC56-2) and π-pHis (SC1-1; SC50-3) monoclonal antibodies were used to show that the BSA-G-τ-pHis and BSA-G-π-pHis conjugates could be used to assess the selectivity of pHis antibodies in a competitive ELISA. Subsequently, the selectivity of the pHis antibodies generated by using phosphopyrazole 8 and pyridyl amino amide 13 as haptens was assessed by competitive ELISA against His, pSer, pThr, pTyr, τ-pHis and π-pHis. Antibodies generated by using phosphopyrazole 8 as a hapten were found to be selective for τ-pHis, and antibodies generated by using pyridyl amino amide 13 were found to be selective for π-pHis. Both τ- and π-pHis antibodies were shown to be effective in immunological experiments, including ELISA, western blot, and immunofluorescence. The τ-pHis antibody was also shown to be useful in the immunoprecipitation of proteins containing pHis.

Proline-mediated modulation on DNA repair pathway in rice seedlings under chromium stress by integrating gene chip and co-expression network analysis.

Chromium (Cr) stress can cause oxidative burst to plants. Application of exogenous proline (Pro) is one of the most effective approaches to improve the tolerance of plants to Cr stress. In this study, we integrated the data of gene chip with co-expression network analysis to identify the key pathways involved in the DNA repair processes in rice seedlings under Cr(VI) stress. Based on KEGG pathway analysis, 158 genes identified are activated in five different types of DNA repair pathways, namely base excision repair (BER, 20 genes), mismatch repair (MMR, 30 genes), nonhomologous end joining (NHEJ, 8 genes), nucleotide excision repair (NER, 56 genes) and homologous recombination (HR, 44 genes). Co-expression network analysis showed that genes activated in DNA repair pathways were categorized into six different modules, wherein Module 1 (45.36%), Module 2 (27.84%) and Module 3 (19.59%) carried more weight than others. Integrating the data of gene chip and co-expression network analysis indicated that coordinated actions of HR and NER pathways are mainly associated with DNA repair processes in Cr(VI)-treated rice seedlings supplied with exogenous Pro. OsCSB, OsXPG, OsBRIP1, OsRAD51C, OsRAD51A2, OsRPA, OsTOPBP1C, OsTOP3, and OsXRCC3 activated in the HR pathway had a stronger impact on repairing DNA damage induced by Cr(VI) stress in rice seedlings supplied with exogenous Pro, while OsXPB1, OsTTDA2, OsTFIIH1, OsXPC, OsRAD23, OsDSS1, and OsRPA located at the NER pathway showed more contribution to repairing DNA damage than others.

Tracing the pollution and human risks of potentially toxic elements in agricultural area nearby the cyanide baths from an active private gold mine in Hainan Province, China.

Mining activities are well-known sources of potentially toxic elements (PTEs) pollution, which often jeopardize the biosphere, pedosphere, and hydrosphere. However, the soil and groundwater pollution caused by active private mining activities has long been neglected. This study investigated the occurrence of PTEs and cyanide (CN) in agricultural soils, mine tailings, and groundwater nearby the cyanide baths from a private gold mine in Hainan Province, southern China. Results indicated that concentrations of Pb, As, Cd, Hg, and CN in different soil depths and mine tailings were up to ten thousand mg/kg, and relatively higher content of As and Pb was detected in groundwater. The chemical forms of Cd, Pb, As, and Hg varied greatly in different soil depths; over 80% of Cd distributed in the water-soluble fraction, suggesting its higher mobility in soils, while approximately 60-90% of Pb, As, and Hg distributed in other chemical fractions, indicating relatively lower mobility in soils. The pollution indices also revealed the serious pollution and deterioration of site quality in this area. Human risk assessments also reflected a high non-carcinogenic/carcinogenic health risk in this area. The framework of integrated management strategies for private metal mines was proposed to mitigate PTEs pollution and reduce health risks.

Estimating the synergistic and antagonistic effects of dual antibiotics on plants through root elongation test.

Antibiotics are recently recognized as a group of emerging environmental contaminants that are frequently detected in various environmental matrixes. Relative root elongation (RRE) test is a rapid and effective strategy to evaluate the water/soil quality and the toxic effects of environmental contaminants on plants. In the present study, we examine the toxicity effect of ciprofloxacin (CIP), norfloxacin (NOR), and tetracycline (TET) to pakchoi individually and in combinations. Both independent action (IA) and concentration addition (CA) models are used for toxicity assessment. Results showed that the EC50 values of CIP, NOR, and TET are 193.59, 60.81, and 40.37 µM, respectively. Combinations of TET + CIP and TET + NOR caused more inhibitory effects on root elongation than those of CIP + NOR. Toxic Unit (TU) and Synergistic Ratio (SR) analysis showed that the relatively lower (higher) EC values are observed in the combinations with lower (higher) antibiotic concentrations, suggesting an effect of low-dose synergism and high-dose antagonism. The reliability of the simulation results from IA and CA models to predict that combined toxicity is highly dependent upon the results from the analysis of TU or SR.

A modelling study of a buffer zone in abating heavy metal contamination from a gold mine of Hainan Province in nearby agricultural area.

The establishment of new buffer zone in the mine areas lacks the basis of theoretical model. As a case study, this study presents the partition model of new buffer zone in a small-scale mine area located in the remote mountainous region of Hainan province, China. The investigation carried out by integration of geostatistical interpolation maps using unmanned aerial vehicle has revealed that As, Cd, Pb, Zn, and Hg are mainly distributed near the tailing ponds and the dressing plant, while Cr and Cu are prominent near the agricultural area. The partition model of buffer zone was established in accordance to the transport velocity of the liquid phase heavy metal in soil. The boundary line of buffer zone is integrated by comparing the 'predicted' heavy metal concentrations with the 'measured' heavy metal concentrations. Principal component analysis (PCA) and the variations of heavy metal concentrations with elevation, slope, and distance were performed to further evaluate the reliability of the predicted buffer zone, indicating that the new buffer zone has a significant effect on minimizing transport of heavy metals from the mining area into the agricultural land. This study is suggestive to provide risk control and sustainable development strategy for the ecosystem protection in mine areas.

Intravitreal injection of mesenchymal stem cells evokes retinal vascular damage in rats.

The aim of this study is to investigate the vascular outcome after intravitreal mesenchymal stem cell (MSC) administration in rats without or with damage to the neurovascular unit [transgenic (TGR) rats]. Male Sprague-Dawley (SD) and TGR rats received an intravitreal injection of 2 × 104 rat bone marrow-derived MSCs (BMSCs) or human adipose-derived stem cells (ASCs) at postnatal d 30. After 4 wk, vasculature, neuronal function, and gene expression in the retinas were evaluated using retinal morphometry, electroretinography, immunofluorescence, Western blot, and quantitative PCR. Intravitreal administration of rat BMSCs and human ASCs in both SD and TGR eyes induced cataract, loss of pericytes, and increased formation of acellular capillaries. BMSCs remained in the vitreous cavity and did not migrate into the retinas. Intravitreal administration of BMSCs impacted retinal neuronal function in neither SD nor TGR rats. Retinal glial activation, elevation of IL-1ß, C3, arginase 1, and heat shock protein 90 were detected in BMSC-injected SD rats. Intravitreal administration of MSCs induces cataract, retinal vasoregression, activation of retinal glial cells, and inflammatory response in rat eyes.-Huang, H., Kolibabka, M., Eshwaran, R., Chatterjee, A., Schlotterer, A., Willer, H., Bieback, K., Hammes, H.-P., Feng, Y. Intravitreal injection of mesenchymal stem cells evokes retinal vascular damage in rats.

Role of the Ang2-Tie2 Axis in Vascular Damage Driven by High Glucose or Nucleoside Diphosphate Kinase B Deficiency.

Ablation of nucleoside diphosphate kinase B (NDPK-B) in mice causes a breakdown of the neurovascular unit in the retina, mimicking diabetic retinopathy. The NDPK-B deficiency-induced vascular damage is mediated by excessive angiopoietin 2 (Ang2). Herein, the potential involvement of its receptor, Tie2, was investigated. NDPK-B-deficient mouse retinas showed an upregulation of Tie2, specifically in the deep capillary layer. A similar upregulation of Tie2 was observed in cultured endothelial cells (ECs) from different origins upon NDPK-B depletion, whereas high glucose (HG) treatment did not alter Tie2 expression. Immunofluorescence staining and subcellular fractionation showed that the majority of Tie2 upregulation occurred at the plasma membrane. Similar to HG, however, NDPK-B depletion reduced Tie2 tyrosine phosphorylation. Compared to HG, a stronger increase of Ang2 was observed in NDPK-B depleted ECs. Treatment of ECs with soluble Tie2 or siRNA-mediated Tie2 knockdown attenuated NDPK-B depletion- but not HG-induced Ang2 upregulation. Like NDPK-B depletion, overexpression of recombinant Ang2 in ECs enhanced Ang2 secretion and concomitantly promoted the upregulation of Tie2. Thus, we identified a new mechanism showing that after reaching a threshold level of secretion, Ang2 sustains its own expression and secretion by a Tie2-dependent positive feedback loop.

Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update.

Heterotrimeric G proteins are pivotal mediators of cellular signal transduction in eukaryotic cells and abnormal G-protein signaling plays an important role in numerous diseases. During the last two decades it has become evident that the activation status of heterotrimeric G proteins is both highly localized and strongly regulated by a number of factors, including a receptor-independent activation pathway of heterotrimeric G proteins that does not involve the classical GDP/GTP exchange and relies on nucleoside diphosphate kinases (NDPKs). NDPKs are NTP/NDP transphosphorylases encoded by the nme/nm23 genes that are involved in a variety of cellular events such as proliferation, migration, and apoptosis. They therefore contribute, for example, to tumor metastasis, angiogenesis, retinopathy, and heart failure. Interestingly, NDPKs are translocated and/or upregulated in human heart failure. Here we describe recent advances in the current understanding of NDPK functions and how they have an impact on local regulation of G-protein signaling.

Transcription of Inflammatory Cytokine TNFα is Upregulated in Retinal Angiogenesis under Hyperoxia.

BACKGROUND/AIMS: Hypoxia induces angiogenesis while hyperoxia promotes vasoregression in the retina. We investigated herein the effect of prolonged hyperoxia on retinal angiogenesis and the underlying mechanism in an oxygen-induced retinopathy (OIR) model. METHODS: Vascular morphology was quantified in whole-mount retina from the mice subjected to the conventional OIR model (c-OIR) or the OIR model with prolonged hyperoxia (p-OIR). Expressions of genes related to angiogenesis were determined by real-time PCR. RESULTS: p-OIR retinas showed few intraretinal neovascular tufts at the border of avascular zones, lacking preretinal neovascularization, whereas c-OIR retinas had numerous preretinal neovascularizations. p-OIR retinas demonstrated outgrowth of capillaries in the deep layers despite persistent hyperoxia and possess a larger avascular zone compared with the c-OIR retinas. The capillaries in the p-OIR retinas were well-formed in contrast to those in the c-OIR retinas. p-OIR retinas expressed significantly higher TNFα (∼4 fold) than c-OIR retinas. The expression of vascular endothelial growth factor, Erythropoietin, Angiopoietin 1 and 2 remained unchanged. CONCLUSION: Our data demonstrate that TNFα transcription is increased in hyperoxia-promoted retinal angiogenesis, implicating it, in association with low VEGF levels, as a possible proponent in retinal angiogenesis under hyperoxia.

Nucleoside diphosphate kinase B-activated intermediate conductance potassium channels are critical for neointima formation in mouse carotid arteries.

OBJECTIVE: Vascular smooth muscle cells (VSMC) proliferation is a hallmark of atherosclerosis and vascular restenosis. The intermediate conductance Ca(2+)-activated K(+) (SK4) channel is required for pathological VSMC proliferation. In T lymphocytes, nucleoside diphosphate kinase B (NDPKB) has been implicated in SK4 channel activation. We thus investigated the role of NDPKB in the regulation of SK4 currents (ISK4) in proliferating VSMC and neointima formation. APPROACH AND RESULTS: Function and expression of SK4 channels in VSMC from injured mouse carotid arteries were assessed by patch-clamping and real-time polymerase chain reaction. ISK4 was detectable in VSMC from injured but not from uninjured arteries correlating with the occurrence of the proliferative phenotype. Direct application of NDPKB to the membrane of inside-out patches increased ISK4, whereas NDPKB did not alter currents in VSMC obtained from injured vessels of SK4-deficient mice. The NDPKB-induced increase in ISK4 was prevented by protein histidine phosphatase 1, but not an inactive protein histidine phosphatase 1 mutant indicating that ISK4 is regulated via histidine phosphorylation in proliferating VSMC; moreover, genetic NDPKB ablation reduced ISK4 by 50% suggesting a constitutive activation of ISK4 in proliferating VSMC. In line, neointima formation after wire injury of the carotid artery was substantially reduced in mice deficient in SK4 channels or NDPKB. CONCLUSIONS: NDPKB to SK4 signaling is required for neointima formation. Constitutive activation of SK4 by NDPKB in proliferating VSMC suggests that targeting this interaction via, for example, activation of protein histidine phosphatase 1 may provide clinically meaningful effects in vasculoproliferative diseases such as atherosclerosis and post angioplasty restenosis.

Nucleoside diphosphate kinase B regulates angiogenesis through modulation of vascular endothelial growth factor receptor type 2 and endothelial adherens junction proteins.

OBJECTIVE: Nucleoside diphosphate kinase B (NDPKB) participates in the activation of heterotrimeric and monomeric G proteins, which are pivotal mediators in angiogenic signaling. The role of NDPKB in angiogenesis has to date not been defined. Therefore, we analyzed the contribution of NDPKB to angiogenesis and its underlying mechanisms in well-characterized in vivo and in vitro models. APPROACH AND RESULTS: Zebrafish embryos were depleted of NDPKB by morpholino-mediated knockdown. These larvae displayed severe malformations specifically in vessels formed by angiogenesis. NDPKB-deficient (NDPKB(-/-)) mice were subjected to oxygen-induced retinopathy. In this model, the number of preretinal neovascularizations in NDPKB(-/-) mice was strongly reduced in comparison with wild-type littermates. In accordance, a delayed blood flow recovery was detected in the NDPKB(-/-) mice after hindlimb ligation. In in vitro studies, a small interfering RNA-mediated knockdown of NDPKB was performed in human umbilical endothelial cells. NDPKB depletion impaired vascular endothelial growth factor (VEGF)-induced sprouting and hampered the VEGF-induced spatial redistributions of the VEGF receptor type 2 and VE-cadherin at the plasma membrane. Concomitantly, NDPKB depletion increased the permeability of the human umbilical endothelial cell monolayer. CONCLUSIONS: This is the first report to show that NDPKB is required for VEGF-induced angiogenesis and contributes to the correct localization of VEGF receptor type 2 and VE-cadherin at the endothelial adherens junctions. Therefore, our data identify NDPKB as a novel molecular target to modulate VEGF-dependent angiogenesis.

Phytotoxicity and Transport of Gallium (Ga) in Rice Seedlings for 2-Day of Exposure.

Hydroponic experiments were conducted with rice seedlings to investigate the accumulation and phytotoxicity of gallium nitrate. A linear decrease in relative growth rate, transpiration rate and water use efficiency was observed in rice seedlings with increasing Ga concentrations. However, inhibition of these selected parameters was noted different at different Ga treatments. Relative growth rate was more sensitive towards Ga treatments. Phyto-transport of Ga was apparent, but recovery of Ga in different parts of rice seedlings varied significantly: roots were dominant site for Ga accumulation. The total accumulation rates of Ga were positively correlated to Ga concentrations. Results indicated that the addition of Ga did not cause deleterious effects on plant physiological functions over a 2-day exposure period. Large amounts of Ga were removed from the hydroponic solution through rice seedlings. Accumulation of Ga in plant tissues resulted in growth inhibition of rice seedlings.

Unraveling the enigma of NPP variation in Chinese vegetation ecosystems: The interplay of climate change and land use change.

Global carbon emissions have exacerbated the greenhouse effect, exerting a profound impact on ecosystems worldwide. Gaining an understanding of the fluctuations in vegetation net primary productivity (NPP) is pivotal in the assessment of environmental quality, estimation of carbon source/sink potential, and facilitation of ecological restoration. Employing MODIS and meteorological data, we conducted a comprehensive analysis of NPP evolution in Chinese vegetation ecosystems (VESs), employing Theil-Sen median trend analysis and the Mann-Kendall test. Furthermore, utilizing scenario-based analysis, we quantitatively determined the respective contributions of climate change and land use change to NPP variations across various scales. The overall NPP exhibited a discernible upward trend from 2000 to 2020, with a growth rate of 5.83 gC·m-2·year-1. Forestland ecosystem (FES) displayed the highest rate of increase (9.40 gC·m-2·year-1), followed by cropland ecosystem (CES) (4.00 gC·m-2·year-1) and grassland ecosystem (GES) (3.40 gC·m-2·year-1). Geographically, NPP exhibited a spatial pattern characterized by elevated values in the southeast and diminished values in the northwest. In addition, climate change had elevated 76.39 % of CES NPP, 90.62 % of FES NPP, and 71.78 % of GES NPP. At the national level, climate change accounted for 83.14 % of the NPP changes, while land use change contributed 14.14 %. Notably, climate change emerged as the primary driving force behind NPP variations across all VEGs, with land use change exerting the most pronounced influence on CES. At the grid scale (2 km × 2 km), land use change played a substantial role in all VEGs, contributing 60.01 % in CES, 54.20 % in FES, and 55.61 % in GES of the NPP variations.

An integration of physiology, transcriptomics, and proteomics reveals carbon and nitrogen metabolism responses in alfalfa (Medicago sativa L.) exposed to titanium dioxide nanoparticles.

Nanoparticle (NP) pollution has negative impacts and is a major global environmental problem. However, the molecular response of alfalfa (Medicago sativa L.) to titanium dioxide nanoparticles (TiO2 NPs) is limited. Herein, the dual effects of TiO2 NPs (0-1000 mg L-1) on carbon (C) and nitrogen (N) metabolisms in alfalfa were investigated. The results showed that 500 mg L-1 TiO2 NPs (Ti-500) had the highest phytotoxicity in the C/N metabolizing enzymes; and it significantly increased total soluble sugar, starch, sucrose, and sucrose-phosphate synthase. Furthermore, obvious photosynthesis responses were found in alfalfa exposed to Ti-500. By contrast, 100 mg L-1 TiO2 NPs (Ti-100) enhanced N metabolizing enzymes. RNA-seq analyses showed 4265 and 2121 differentially expressed genes (DEGs) in Ti-100 and Ti-500, respectively. A total of 904 and 844 differentially expressed proteins (DEPs) were identified in Ti-100 and Ti-500, respectively. Through the physiological, transcriptional, and proteomic analyses, the DEGs and DEPs related to C/N metabolism, photosynthesis, chlorophyll synthesis, starch and sucrose metabolism, and C fixation in photosynthetic organisms were observed. Overall, TiO2 NPs at low doses improve photosynthesis and C/N regulation, but high doses can cause toxicity. It is valuable for the safe application of NPs in agriculture.

Microbiological and metabolic pathways analysing the mechanisms of alfalfa polysaccharide and sulfated alfalfa polysaccharide in alleviating obesity.

Alfalfa polysaccharide (AP) and sulfated alfalfa polysaccharide (SAP) exhibit potential for alleviating obesity. This study aimed to analyze the mechanism of action of AP and SAP in alleviating obesity through combined microbiomics and metabolomics. The research selected validated optimal AP and SAP concentration for experiment. The results showed that AP and SAP down-regulated colonic inflammatory gene expression, regulated intestinal pH to normal, and restored intestinal growth. Microbial sequencing showed that AP and SAP altered the microbial composition ratio. AP increased the relative abundance of Muribaculaceae and Romboutsia. SAP increased the relative abundance of Dubosiella, Fecalibaculum and Desulfovibrionaceae. Metabolomic analysis showed that AP regulated steroid hormone biosynthesis, neuroactive ligand-receptor interactions and bile secretion pathways. SAP focuses more on pathways related to amino acid metabolism. Meanwhile, AP and SAP down-regulated the mRNA expression of colonic COX-2, PepT-1 and HK2 and up-regulated the mRNA expression of TPH1. Correlation analysis showed a strong correlation between metabolites and gut bacteria. Dubosiella, Faecalibaculum may be the critical marker flora for polysaccharides to alleviate obesity. This study indicates that AP and SAP alleviate obesity through different pathways and that specific polysaccharide modifications affect characteristic microbial and metabolic pathways, providing new insights into polysaccharide modifications.

Zinc oxide nanoparticles alleviate cadmium toxicity and promote tolerance by modulating programmed cell death in alfalfa (Medicago sativa L.).

Cadmium (Cd) can induce programmed cell death (PCD) and zinc oxide nanoparticles (ZnO NPs) effectively alleviate Cd stress. However, the mechanisms of ZnO NPs-mediated Cd detoxification in alfalfa (Medicago sativa L.) are limited. The pot experiment was conducted with Cd soil (19.2 mg kg-1) and foliar ZnO NPs (100 mg L-1) on alfalfa. The results showed that Cd reduced shoot height and biomass, and accumulated reactive oxygen species (ROS), resulting in oxidative stress and further PCD (plasmolysis, cytosolic and nuclear condensation, subcellular organelle swelling, and cell death). ZnO NPs positively regulated the antioxidant system, cell membrane stability, ultrastructure, osmotic homeostasis, and reduced PCD, indicating a multi-level coordination for the increased Cd tolerance. ZnO NPs up-regulated the activity and expression of antioxidant enzymes and regulated PCD-related genes to scavenge ROS and mitigate PCD caused by Cd. The genes related to ZnO NPs-mediated Cd detoxification were significantly enriched in cell death and porphyrin and chlorophyll metabolism. Overall, it elucidates the molecular basis of ZnO NPs-mediated Cd-tolerance by promoting redox and osmotic homeostasis, maintaining cellular ultrastructure, reducing Cd content, and attenuating Cd-induced PCD. it provides a promising application of ZnO NPs to mitigate Cd phytotoxicity and the related cellular and biochemical mechanisms. ENVIRONMENTAL IMPLICATION: Cd, one of the most toxic heavy metals, has caused serious environmental pollution. ZnO NPs can effectively alleviate Cd stress on plants and the environment. This study revealed that foliar-applied ZnO NPs alleviate Cd toxicity by mitigating the oxidative damage and regulating Cd-induced PCD via morphological, physiological, and transcriptomic levels. The findings elucidated the molecular basis of ZnO NPs-mediated Cd tolerance by promoting osmotic and redox homeostasis, reducing Cd content and lipid peroxidation, attenuating Cd-induced PCD features, and altering PCD-related genes in alfalfa. The study laid a theoretical foundation for the safe production of alfalfa under Cd pollution.