Aus rice root architecture variation contributing to grain yield under drought suggests a key role of nodal root diameter class.

The aus rice variety group originated in stress-prone regions and is a promising source for the development of new stress-tolerant rice cultivars. In this study, an aus panel (~220 genotypes) was evaluated in field trials under well-watered and drought conditions and in the greenhouse (basket, herbicide and lysimeter studies) to investigate relationships between grain yield and root architecture, and to identify component root traits behind the composite trait of deep root growth. In the field trials, high and stable grain yield was positively related to high and stable deep root growth (r = 0.16), which may indicate response to within-season soil moisture fluctuations (i.e., plasticity). When dissecting component traits related to deep root growth (including angle, elongation and branching), the number of nodal roots classified as 'large-diameter' was positively related to deep root growth (r = 0.24), and showed the highest number of colocated genome-wide association study (GWAS) peaks with grain yield under drought. The role of large-diameter nodal roots in deep root growth may be related to their branching potential. Two candidate loci that colocated for yield and root traits were identified that showed distinct haplotype distributions between contrasting yield/stability groups and could be good candidates to contribute to rice improvement.

PDF1.5 Enhances Adaptation to Low Nitrogen Levels and Cadmium Stress.

Environmental acclimation ability plays a key role in plant growth, although the mechanism remains unclear. Here, we determined the involvement of Arabidopsis thaliana PLANT DEFENSIN 1 gene AtPDF1.5 in the adaptation to low nitrogen (LN) levels and cadmium (Cd) stress. Histochemical analysis revealed that AtPDF1.5 was mainly expressed in the nodes and carpopodium and was significantly induced in plants exposed to LN conditions and Cd stress. Subcellular localization analysis revealed that AtPDF1.5 was cell wall- and cytoplasm-localized. AtPDF1.5 overexpression significantly enhanced adaptation to LN and Cd stress and enhanced the distribution of metallic elements. The functional disruption of AtPDF1.5 reduced adaptations to LN and Cd stress and impaired metal distribution. Under LN conditions, the nitrate transporter AtNRT1.5 expression was upregulated. Nitrate transporter AtNRT1.8 expression was downregulated when AtPDF1.5 was overexpressed, resulting in enhanced transport of NO3- to shoots. In response to Cd treatment, AtPDF1.5 regulated the expression of metal transporter genes AtHMP07, AtNRAMP4, AtNRAMP1, and AtHIPP3, resulting in higher Cd accumulation in the shoots. We conclude that AtPDF1.5 is involved in the processing or transmission of signal substances and plays an important role in the remediation of Cd pollution and LN adaptation.

Ammonium Accumulation Caused by Reduced Tonoplast V-ATPase Activity in Arabidopsis thaliana.

Plant vacuoles are unique compartments that play a critical role in plant growth and development. The vacuolar H+-ATPase (V-ATPase), together with the vacuolar H+-pyrophosphatase (V-PPase), generates the proton motive force that regulates multiple cell functions and impacts all aspects of plant life. We investigated the effect of V-ATPase activity in the vacuole on plant growth and development. We used an Arabidopsisthaliana (L.) Heynh. double mutant, vha-a2 vha-a3, which lacks two tonoplast-localized isoforms of the membrane-integral V-ATPase subunit VHA-a. The mutant is viable but exhibits impaired growth and leaf chlorosis. Nitrate assimilation led to excessive ammonium accumulation in the shoot and lower nitrogen uptake, which exacerbated growth retardation of vha-a2 vha-a3. Ion homeostasis was disturbed in plants with missing VHA-a2 and VHA-a3 genes, which might be related to limited growth. The reduced growth and excessive ammonium accumulation of the double mutant was alleviated by potassium supplementation. Our results demonstrate that plants lacking the two tonoplast-localized subunits of V-ATPase can be viable, although with defective growth caused by multiple factors, which can be alleviated by adding potassium. This study provided a new insight into the relationship between V-ATPase, growth, and ammonium accumulation, and revealed the role of potassium in mitigating ammonium toxicity.

Integrated Transcriptional and Proteomic Profiling Reveals Potential Amino Acid Transporters Targeted by Nitrogen Limitation Adaptation.

Nitrogen (N) is essential for plant growth and crop productivity. Organic N is a major form of remobilized N in plants' response to N limitation. It is necessary to understand the regulatory role of N limitation adaption (NLA) in organic N remobilization for this adaptive response. Transcriptional and proteomic analyses were integrated to investigate differential responses of wild-type (WT) and nla mutant plants to N limitation and to identify the core organic N transporters targeted by NLA. Under N limitation, the nla mutant presented an early senescence with faster chlorophyll loss and less anthocyanin accumulation than the WT, and more N was transported out of the aging leaves in the form of amino acids. High-throughput transcriptomic and proteomic analyses revealed that N limitation repressed genes involved in photosynthesis and protein synthesis, and promoted proteolysis; these changes were higher in the nla mutant than in the WT. Both transcriptional and proteomic profiling demonstrated that LHT1, responsible for amino acid remobilization, were only significantly upregulated in the nla mutant under N limitation. These findings indicate that NLA might target LHT1 and regulate organic N remobilization, thereby improving our understanding of the regulatory role of NLA on N remobilization under N limitation.

Genome-Wide Differential DNA Methylation and miRNA Expression Profiling Reveals Epigenetic Regulatory Mechanisms Underlying Nitrogen-Limitation-Triggered Adaptation and Use Efficiency Enhancement in Allotetraploid Rapeseed.

Improving crop nitrogen (N) limitation adaptation (NLA) is a core approach to enhance N use efficiency (NUE) and reduce N fertilizer application. Rapeseed has a high demand for N nutrients for optimal plant growth and seed production, but it exhibits low NUE. Epigenetic modification, such as DNA methylation and modification from small RNAs, is key to plant adaptive responses to various stresses. However, epigenetic regulatory mechanisms underlying NLA and NUE remain elusive in allotetraploid B. napus. In this study, we identified overaccumulated carbohydrate, and improved primary and lateral roots in rapeseed plants under N limitation, which resulted in decreased plant nitrate concentrations, enhanced root-to-shoot N translocation, and increased NUE. Transcriptomics and RT-qPCR assays revealed that N limitation induced the expression of NRT1.1, NRT1.5, NRT1.7, NRT2.1/NAR2.1, and Gln1;1, and repressed the transcriptional levels of CLCa, NRT1.8, and NIA1. High-resolution whole genome bisulfite sequencing characterized 5094 differentially methylated genes involving ubiquitin-mediated proteolysis, N recycling, and phytohormone metabolism under N limitation. Hypermethylation/hypomethylation in promoter regions or gene bodies of some key N-metabolism genes might be involved in their transcriptional regulation by N limitation. Genome-wide miRNA sequencing identified 224 N limitation-responsive differentially expressed miRNAs regulating leaf development, amino acid metabolism, and plant hormone signal transduction. Furthermore, degradome sequencing and RT-qPCR assays revealed the miR827-NLA pathway regulating limited N-induced leaf senescence as well as the miR171-SCL6 and miR160-ARF17 pathways regulating root growth under N deficiency. Our study provides a comprehensive insight into the epigenetic regulatory mechanisms underlying rapeseed NLA, and it will be helpful for genetic engineering of NUE in crop species through epigenetic modification of some N metabolism-associated genes.

SPION-Decorated Exosome Delivered BAY55-9837 Targeting the Pancreas through Magnetism to Improve the Blood GLC Response.

BAY55-9837, a potential therapeutic peptide in the treatment of type 2 diabetes mellitus (T2DM), is capable of inducing glucose (GLC)-dependent insulin secretion. However, the therapeutic benefit of BAY55-9837 is limited by its short half-life, lack of targeting ability, and poor blood GLC response. How to improve the blood GLC response of BAY55-9837 is an existing problem that needs to be solved. In this study, a method for preparing BAY55-9837-loaded exosomes coupled with superparamagnetic iron oxide nanoparticle (SPIONs) with pancreas islet targeting activity and an enhanced blood GLC response with the help of an external magnetic force (MF) is demonstrated. The plasma half-life of BAY55-9837 loaded in exosome-SPION is 27-fold longer than that of BAY55-9837. The active targeting property of SIPONs enables BAY-exosomes to gain a favorable targeting property, which improves the BAY55-9837 blood GLC response capacity with the help of an external MF. In vivo studies show that BAY-loaded exosome-based vehicle delivery enhances pancreas islet targeting under an external MF and markedly increases insulin secretion, thereby leading to the alleviation of hyperglycemia. The chronic administration of BAY-exosome-SPION/MF significantly improves glycosylated hemoglobin and lipid profiles. BAY-exosome-SPION/MF maybe a promising candidate for a peptide drug carrier for T2DM with a better blood GLC response.

NRT1.1-Related NH4 + Toxicity Is Associated with a Disturbed Balance between NH4 + Uptake and Assimilation.

A high concentration of ammonium (NH4 +) as the sole source of nitrogen in the growth medium often is toxic to plants. The nitrate transporter NRT1.1 is involved in mediating the effects of NH4 + toxicity; however, the mechanism remains undefined. In this study, wild-type Arabidopsis (Arabidopsis thaliana Columbia-0 [Col-0]) and NRT1.1 mutants (chl1-1 and chl1-5) were grown hydroponically in NH4NO3 and (NH4)2SO4 media to assess the function of NRT1.1 in NH4 + stress responses. All the plants grew normally in medium containing mixed nitrogen sources, but Col-0 displayed more chlorosis and lower biomass and photosynthesis than the NRT1.1 mutants in (NH4)2SO4 medium. Grafting experiments between Col-0 and chl1-5 further confirmed that NH4 + toxicity is influenced by NRT1.1. In (NH4)2SO4 medium, NRT1.1 induced the expression of NH4 + transporters, increasing NH4 + uptake. Additionally, the activities of glutamine synthetase and glutamate synthetase in roots of Col-0 plants decreased and soluble sugar accumulated significantly, whereas pyruvate kinase-mediated glycolysis was not affected, all of which contributed to NH4 + accumulation. By contrast, the NRT1.1 mutants showed reduced NH4 + accumulation and enhanced NH4 + assimilation through glutamine synthetase, glutamate synthetase, and glutamate dehydrogenase. Moreover, the up-regulation of genes involved in ethylene synthesis and senescence in Col-0 plants treated with (NH4)2SO4 suggests that ethylene is involved in NH4 + toxicity responses. This study showed that NH4 + toxicity is related to a nitrate-independent signaling function of NRT1.1 in Arabidopsis, characterized by enhanced NH4 + accumulation and altered NH4 + metabolism, which stimulates ethylene synthesis, leading to plant senescence.

A multiomics approach reveals the pivotal role of subcellular reallocation in determining rapeseed resistance to cadmium toxicity.

Oilseed rape (Brassica napus) has great potential for phytoremediation of cadmium (Cd)-polluted soils due to its large plant biomass production and strong metal accumulation. Enhanced plant Cd resistance (PCR) is a crucial prerequisite for phytoremediation through hyper-accumulation of excess Cd. However, the complexity of the allotetraploid genome of rapeseed hinders our understanding of PCR. To explore rapeseed Cd-resistance mechanisms, we examined two genotypes, 'ZS11' (Cd-resistant) and 'W10' (Cd-sensitive), that exhibit contrasting PCR while having similar tissue Cd concentrations, and characterized their different fingerprints in terms of plant morphophysiology (electron microscopy), ion abundance (inductively coupled plasma mass spectrometry), DNA variation (whole-genome resequencing), transcriptomics (high-throughput mRNA sequencing), and metabolomics (ultra-high performance liquid chromatography-mass spectrometry). Fine isolation of cell components combined with ionomics revealed that more Cd accumulated in the shoot vacuoles and root pectins of the resistant genotype than in the sensitive one. Genome and transcriptome sequencing identified numerous DNA variants and differentially expressed genes involved in pectin modification, ion binding, and compartmentalization. Transcriptomics-assisted gene co-expression networks characterized BnaCn.ABCC3 and BnaA8.PME3 as the central members involved in the determination of rapeseed PCR. High-resolution metabolic profiles revealed greater accumulation of shoot Cd chelates, and stronger biosynthesis and higher demethylation of root pectins in the resistant genotype than in the sensitive one. Our comprehensive examination using a multiomics approach has greatly improved our understanding of the role of subcellular reallocation of Cd in the determination of PCR.

Integrated physiologic, genomic and transcriptomic strategies involving the adaptation of allotetraploid rapeseed to nitrogen limitation.

BACKGROUND: Nitrogen (N) is a macronutrient that is essential for optimal plant growth and seed yield. Allotetraploid rapeseed (AnAnCnCn, 2n = 4x = 38) has a higher requirement for N fertilizers whereas exhibiting a lower N use efficiency (NUE) than cereal crops. N limitation adaptation (NLA) is pivotal for enhancing crop NUE and reducing N fertilizer use in yield production. Therefore, revealing the genetic and molecular mechanisms underlying NLA is urgent for the genetic improvement of NUE in rapeseed and other crop species with complex genomes. RESULTS: In this study, we integrated physiologic, genomic and transcriptomic analyses to comprehensively characterize the adaptive strategies of oilseed rape to N limitation stresses. Under N limitations, we detected accumulated anthocyanin, reduced nitrate (NO3-) and total N concentrations, and enhanced glutamine synthetase activity in the N-starved rapeseed plants. High-throughput transcriptomics revealed that the pathways associated with N metabolism and carbon fixation were highly over-represented. The expression of the genes that were involved in efficient N uptake, translocation, remobilization and assimilation was significantly altered. Genome-wide identification and molecular characterization of the microR827-NLA1-NRT1.7 regulatory circuit indicated the crucial role of the ubiquitin-mediated post-translational pathway in the regulation of rapeseed NLA. Transcriptional analysis of the module genes revealed their significant functional divergence in response to N limitations between allotetraploid rapeseed and the model Arabidopsis. Association analysis in a rapeseed panel comprising 102 genotypes revealed that BnaC5.NLA1 expression was closely correlated with the rapeseed low-N tolerance. CONCLUSIONS: We identified the physiologic and genome-wide transcriptional responses of oilseed rape to N limitation stresses, and characterized the global members of the BnamiR827-BnaNLA1s-BnaNRT1.7s regulatory circuit. The transcriptomics-assisted gene co-expression network analysis accelerates the rapid identification of central members within large gene families of plant species with complex genomes. These findings would enhance our comprehensive understanding of the physiologic responses, genomic adaptation and transcriptomic alterations of oilseed rape to N limitations and provide central gene resources for the genetic improvement of crop NLA and NUE.

Nitrogen Use Efficiency Is Mediated by Vacuolar Nitrate Sequestration Capacity in Roots of Brassica napus.

Enhancing nitrogen use efficiency (NUE) in crop plants is an important breeding target to reduce excessive use of chemical fertilizers, with substantial benefits to farmers and the environment. In Arabidopsis (Arabidopsis thaliana), allocation of more NO3 (-) to shoots was associated with higher NUE; however, the commonality of this process across plant species have not been sufficiently studied. Two Brassica napus genotypes were identified with high and low NUE. We found that activities of V-ATPase and V-PPase, the two tonoplast proton-pumps, were significantly lower in roots of the high-NUE genotype (Xiangyou15) than in the low-NUE genotype (814); and consequently, less vacuolar NO3 (-) was retained in roots of Xiangyou15. Moreover, NO3 (-) concentration in xylem sap, [(15)N] shoot:root (S:R) and [NO3 (-)] S:R ratios were significantly higher in Xiangyou15. BnNRT1.5 expression was higher in roots of Xiangyou15 compared with 814, while BnNRT1.8 expression was lower. In both B. napus treated with proton pump inhibitors or Arabidopsis mutants impaired in proton pump activity, vacuolar sequestration capacity (VSC) of NO3 (-) in roots substantially decreased. Expression of NRT1.5 was up-regulated, but NRT1.8 was down-regulated, driving greater NO3 (-) long-distance transport from roots to shoots. NUE in Arabidopsis mutants impaired in proton pumps was also significantly higher than in the wild type col-0. Taken together, these data suggest that decrease in VSC of NO3 (-) in roots will enhance transport to shoot and essentially contribute to higher NUE by promoting NO3 (-) allocation to aerial parts, likely through coordinated regulation of NRT1.5 and NRT1.8.

Remediation of Petroleum-contaminated Soil Using Bulrush Straw Powder, Biochar and Nutrients.

The aim of this study was to determine the remediation efficiency of petroleum-contaminated soil from an oilfield using different types of remediation treatments under laboratory conditions. Compared with unamended soil as the control treatment (T1), soil samples were amended with bulrush straw powder (T2), with biochar alone (T3) and in combination with nutrients (nitrogen and phosphorus) (T4). The remediation experiment was carried out for 8 weeks. The extent of hydrocarbon degradation was monitored gravimetrically, and the residual oil fractions were analyzed by gas chromatography. The characteristics of the polluted soil (water-holding capacity and nutrients) were improved significantly by biochar addition (p < 0.05). The total microbial count increased significantly in the treatment containing biochar and added nutrients (t = 23.429, p = 0.002). The degradation of total petroleum hydrocarbons (TPH) and the main hydrocarbon fractions was higher in T3 and T4, especially in T4, than in T1 and T2. The intensities of the n-alkane fraction, C27-C29 steranes and C33-C35 homohopanes were efficiently decreased in T4 compared to the other treatments. According to the results, petroleum-contaminated soil can be remediated efficiently by adding biochar and nutrients simultaneously, and this combination of remediation was superior to that observed with added bulrush straw powder.

FGFR antagonist induces protective autophagy in FGFR1-amplified breast cancer cell.

Breast cancer, representing approximately 30% of all gynecological cancer cases diagnosed yearly, is a leading cause of cancer-related mortality for women. Amplification of FGFR1 is frequently observed in breast cancers and is associated with poor prognosis. Though FGFRs have long been considered as anti-cancer drug targets, and a cluster of FGFR antagonists are currently under clinical trials, the precise cellular responses under the treatment of FGFR antagonists remains unclear. Here, we show that PD166866, an FGFR1-selective inhibitor, inhibits proliferation and triggers anoikis in FGFR1-amplified breast cancer cell lines. Notably, we demonstrate that PD166866 induces autophagy in FGFR1-amplified breast cancer cell lines, while blockage of autophagy by Atg5 knockdown further enhances the anti-proliferative activities of PD166866. Moreover, mechanistic study reveals that PD166866 induces autophagy through repressing Akt/mTOR signaling pathway. Together, the present study provides new insights into the molecular mechanisms underlying the anti-tumor activities of FGFR antagonists, and may further assist the FGFRs-based drug discovery.

Snail regulated by PKC/GSK-3ß pathway is crucial for EGF-induced epithelial-mesenchymal transition (EMT) of cancer cells.

Cancer metastasis is considered a major challenge in cancer therapy. Recently, epidermal growth factor (EGF)/epidermal growth factor receptor (EGFR) signaling has been shown to induce epithelial-mesenchymal transition (EMT) and thereby to promote cancer metastasis. However, the underlying mechanism has not been fully elucidated. We demonstrate that EGF can induce EMT in human prostate and lung cancer cells and thus promote invasion and migration. EGF-induced EMT has been characterized by the cells acquiring mesenchymal spindle-like morphology and increasing their expression of N-cadherin and fibronectin, with a concomitant decrease of E-cadherin. Both protein and mRNA expression of transcription factor Snail rapidly increases after EGF treatment. The knockdown of Snail significantly attenuates EGF-induced EMT, suggesting that Snail is crucial for this process. To determine the way that Snail is accumulated, we demonstrate (1) that EGF promotes the stability of Snail via inhibiting the activity of glycogen synthase kinase 3 beta (GSK-3ß), (2) that protein kinase C (PKC) rather than the phosphatidylinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway is responsible for GSK-3ß inhibition and (3) that GSK-3ß inhibition promotes the transcription of Snail. Taken together, these results reveal that the PKC/GSK-3ß signaling pathway controls both the stability and transcription of Snail, which is crucial for EMT induced by EGF in PC-3 and A549 cells. Our study suggests a novel signaling pathway for Snail regulation and provides a better understanding of growth-factor-induced tumor EMT and metastasis.

Promoting antitumor activities of hydroxycamptothecin by encapsulation into acid-labile nanoparticles using electrospraying.

PURPOSE: Acid-labile nanoparticles are proposed to enhance the tumor targeting and anti-tumor therapy of hydroxycamptothecin (HCPT) in response to the acidic microenvironment within cells and tumor tissues. METHODS: HCPT was entrapped into matrix polymers containing acid-labile segments and galactose moieties (PGBELA) through an electrospraying technique. The antitumor activities of HCPT-loaded nanoparticles were evaluated both on HepG2 cells and after intravenous injection into H22 tumor-bearing mice. RESULTS: The electrosprayed nanoparticles were obtained with enhanced loading efficiency and extended release of HCPT compared with other nanoparticle preparation methods. The acid-lability and targeting capability of PGBELA nanoparticles resulted in a 5 times higher inhibitory activity after incubation in pH 6.8 media compared to that of pH 7.4. Animal studies indicated that both the blood circulation time and tumor distribution of PGBELA nanoparticles were significantly increased. HCPT/PGBELA nanoparticles indicated a superior in vivo antitumor activity and fewer side effects than other treatments on the basis of tumor growth, animal survival rate, tissue necrosis and cell apoptosis evaluation. CONCLUSION: Biodegradable PGBELA nanoparticles are capable of achieving site-specific drug delivery by active targeting and triggered release by acidic pH both in tumor tissues and after internalization within tumor cells, thereby providing a novel strategy for cancer treatment.

Morphological classification of neurons based on Sugeno fuzzy integration and multi-classifier fusion.

In order to extract more important morphological features of neuron images and achieve accurate classification of the neuron type, a method is proposed that uses Sugeno fuzzy integral integration of three optimized deep learning models, namely AlexNet, VGG11_bn, and ResNet-50. Firstly, using the pre-trained model of AlexNet and the output layer is fine-tuned to improve the model's performance. Secondly, in the VGG11_bn network, Global Average Pooling (GAP) is adopted to replace the traditional fully connected layer to reduce the number of parameters. Additionally, the generalization ability of the model is improved by transfer learning. Thirdly, the SE(squeeze and excitation) module is added to the ResNet-50 variant ResNeXt-50 to adjust the channel weight and capture the key information of the input data. The GELU activation function is used to better fit the data distribution. Finally, Sugeno fuzzy integral is used to fuse the output of each model to get the final classification result. The experimental results showed that on the Img_raw, Img_resample and Img_XYalign dataset, the accuracy of 4-category classification reached 98.04%, 91.75% and 93.13%, respectively, and the accuracy of 12-category classification reached 97.82%, 85.68% and 87.60%, respectively. The proposed method has good classification performance in the morphological classification of neurons.

[Efficacy of treatment with siRNA targeting Bcl-2 in combination with HCPT against transplanted H22 hepatoma in mice].

OBJECTIVE: To investigate the efficacy of treatment with siRNA targeting Bcl-2 in combination with HCPT against H22 hepatoma transplanted in mice. METHODS: siRNA targeting Bcl-2 mRNA was successfully designed and synthesized. Then, the Bcl-2 siRNA was transfected into H22 hepatoma transplanted in mice in combination with HCPT for treatment. The changes of tumor volume, body weight and survival rate were observed. Tumor tissues were processed into paraffin blocks and sections were stained with hematoxylin and eosin (HE) to investigate the morphological changes of the tumor cells. RT-polymerase chain reaction (PT-PCR) was used to assess the expression of Bcl-2 mRNA in tumors and cells. Cell cycle and apoptosis of H22 hepatoma cells transplanted in mice were further determined by flow cytometry. RESULTS: After treatment for 21 days, the tumor volume was around (571.47 ± 67.31)mm³ in the group of siRNA in combination with HCPT, which was significant smaller than that of the groups of HCPT [(880.47 ± 107.31) mm³, P < 0.05], siRNA interfere [(1119.55 ± 158.60)mm³, P < 0.01] and saline (1357.64 ± 197.92)mm³, P < 0.01]. The median survival time of the group receiving siRNA in combination with HCPT treatment was 26 days, which was significantly longer than that of the group receiving HCPT (14 day, P < 0.05), siRNA interfere (21 day, P < 0.05) and saline (12 day, P < 0.05). Larger necrotic area, lower expression of Bcl-2 mRNA, less cells at S phase and more apoptotic cells could be obviously seen in tumor tissues in the group of siRNA in combination with HCPT treatment. CONCLUSION: Bcl-2 siRNA in combination with HCPT has good synergetic antitumor efficacy in H22 hepatoma-bearing mice.

Probiotic Escherichia coli Nissle 1917 propelled micro-robot with pH sensitivity for hypoxia targeted intestinal tumor therapy.

Poor drug penetration in hypoxia area of solid tumor is a big challenge for intestinal tumor therapy and thus it is crucial to develop an effective strategy to overcome this challenge. Compared with other bacteria used for construction of hypoxia targeted bacteria micro-robot, the Escherichia coli Nissle 1917 (EcN) bacteria are nonpathogenic Gram-negative probiotic and can especially target and identify the signal molecules in the hypoxic region of tumor, and thus, in this study, we choose EcN to construct a bacteria propelled micro-robot for targeting intestinal tumor therapy. Firstly, the MSNs@DOX with average diameter of 200 nm were synthesized and conjugated with EcN bacteria using EDC/NHS chemical crosslinking method to construct a EcN propelled micro-robot. The motility of micro-robot was then evaluated and the motion velocity of EcN-pMSNs@DOX was 3.78 µm/s. Compared with pMSNs@DOX without EcN driven, EcN bacteria propelled micro-robot transported much more pMSNs@DOX into the inner of HCT-116 3D multicellular tumor spheroids. However, the EcN bacteria are non-intracelluar bacteria which lead to the micro-robot can not directly enter into tumor cells. Therefore, we utilized acid-labile linkers of cis-aconitic amido bone to link EcN with MSNs@DOX nanoparticles to achieve the pH sensitive separation of EcN with MSNs@DOX from the micro-robot. At 4 h of incubation, the isolated MSNs@DOX began to enter into the tumor cells through CLSM observation. In vitro live/dead staining results show that EcN-pMSNs@DOX induced much more cell death than pMSNs@DOX at 24 and 48 h of incubation with HCT-116 tumor cells in acid culture media (pH 5.3). For the validation of the therapeutic efficacy of the micro-robot for intestinal tumor, we established the HCT-116 subcutaneous transplantation tumor model. After 28 days of treatment, EcN-pMSNs@DOX dramatically inhibit tumor growth with tumor volume was around 689 mm3, induce much more tumor tissues necrosis and apoptosis. Finally, the toxicity of this micro-robot was investigated by pathological analysis the liver and heart tissues. We expect that the pH sensitive EcN propelled micro-robot here we constructed may be a safe and feasible strategy for intestinal tumor therapy.

Calcium peroxide alleviates the waterlogging stress of rapeseed by improving root growth status in a rice-rape rotation field.

Waterlogging stress has a negative influence on agricultural production, particularly for rapeseed yield in a rice-rape rotation field. To alleviate the profound impacts of waterlogging stress on rapeseed production, a new fertilization with calcium peroxide (CaO2) was proposed. In this field experiment, with the conventional rape (Brassica napus L.) variety fengyou958 (FY958) and early maturing rape variety xiangyou420 (XY420) as materials, waterlogging was imposed from the bud to flowering stage, and three supplies of CaO2 (0, C1 for the 594 kg hm-2 and C2 for the 864 kg hm-2) were added as basal fertilizer. The results showed that CaO2 significantly reduced the accumulation of fermentation products in roots and alleviated the peroxidation of leaves. The reduced waterlogging stress promoted the root vigor and agronomic characters, such as branches, plant height and stem diameter, accelerated dry matter and nutrients accumulation, and resulting in 22.7% (C1) to 232.8% (C2) higher grain yields in XY420, and 112.4% (C1) to 291.8% (C2) higher grain yields in FY958, respectively. In conclusion, 594 kg hm-2 to 864 kg hm-2 CaO2 application restored the growth of waterlogged rapeseed leaves, and reduced the anaerobic intensity of root, which enhanced the resistance of plants to waterlogging, and improved crop productivity. In a certain range, the higher CaO2 application, the more the yield. This study provides a valid method to prevent damage from flooding in crop fields.

A comparison of the mechanisms and performances of Acorus calamus, Pontederia cordata and Alisma plantagoaquatica in removing nitrogen from farmland wastewater.

This study examined the performances of Acorus calamus, Pontederia cordata, and Alisma plantagoaquatica in removing nitrogen (N) from farmland wastewater. P. cordata showed the fastest rate of N removal, followed by A. plantagoaquatica, whereas that of A. calamus was slowest. P. cordata and A. plantagoaquatica achieving a greater rate of TN reduction in soil than that by A. calamus. A. plantagoaquatica demonstrated the highest N adsorption capacity, 32.6% and 392.1% higher than that of P. cordata and A. calamus, respectively. The higher potential nitrification and denitrification rate, and abundance of functional genes in the P. cordata microcosm resulted in a stronger process of nitrification-denitrification, which accounted for 65.99% of TN loss. Plant uptake and nitrification-denitrification were responsible for 50.06% and 49.94% of TN removed within the A. plantagoaquatica. Nitrification-denitrification accounted for 86.35% of TN loss in A. calamus. These findings helped to insight into N removal mechanisms in different plants.

Boron mitigates cadmium toxicity to rapeseed (Brassica napus) shoots by relieving oxidative stress and enhancing cadmium chelation onto cell walls.

In southern China, Brassica napus (rapeseed) is a widely planted oilseed crop in rice-rapeseed rotation systems with characteristically high levels of cadmium (Cd) and low levels of available boron (B). Current knowledge of the ameliorative effects of B on Cd toxicity in plants mainly concerns plant growth, Cd uptake, and Cd translocation, while little attention has been paid to the role of B on plant antioxidant enzyme systems and cell wall chelation of Cd. We explored the mechanisms whereby B improves rapeseed Cd resistance. Application of B alleviated Cd-induced oxidative stress caused by reactive oxygen species (ROS) in the shoots of Cd-treated plants, by increasing the activity of the major antioxidant enzymes, superoxide dismutase, peroxidase, and catalase. Moreover, the shoots of rapeseed plants supplied with B under Cd toxicity had higher ionic soluble pectin (ISP) content, thereby providing more Cd-binding sites in pectin, as well as higher methylesterase activity. However, no changes in covalent soluble pectin were observed. In addition, B also induced higher cellulose in Cd-toxic shoots, thus promoting Cd chelation onto cell walls. Fourier infrared spectrum analysis confirmed that the addition of B increased protein, pectin, cellulose, and carbohydrate content in the cell walls of Cd-toxic leaves. In conclusion, B can mitigate Cd phytotoxicity by alleviating oxidative stress and immobilizing Cd on the ISP and cellulose of shoot cell walls, thereby playing a potential role in improving the growth potential of crops and Cd phytoremediation. The results also provide a theoretical basis for alleviating Cd toxicity in crops and development of Cd-tolerant varieties.