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The bHLH transcription factors play pivotal roles in plant growth and development, production of secondary metabolites and responses to various environmental stresses. Although the bHLH genes have been well studied in model plant species, a comprehensive investigation of the bHLH genes is required for tobacco with newly obtained high-quality genome. In the present study, a total of 309 NtbHLH genes were identified and can be divided into 23 subfamilies. The conserved amino acids which are essential for their function were predicted for the NtbHLH proteins. Moreover, the NtbHLH genes were conserved during evolution through analyzing the gene structures and conserved motifs. A total of 265 NtbHLH genes were localized in the 24 tobacco chromosomes while the remained 44 NtbHLH genes were mapped to the scaffolds due to the complexity of tobacco genome. Moreover, transcripts of NtbHLH genes were obviously tissue-specific expressed from the gene-chip data from 23 tobacco tissues, and expressions of 20 random selected NtbHLH genes were further confirmed by quantitative real-time PCR, indicating their potential functions in the plant growth and development. Importantly, overexpressed NtbHLH86 gene confers improve drought tolerance in tobacco indicating that it might be involved in the regulation of drought stress. Therefore, our findings here provide a valuable information on the characterization of NtbHLH genes and further investigation of their functions in tobacco.

Nicotine is one of the most important secondary metabolites in tobacco, and its biosynthesis can be induced by topping and jasmonic acid treatment. NtMYC2s play pivotal roles in the regulation of nicotine. The mediator server as a bridge betwen the transcription factors and RNA polymerase in order to facilitates transcription and functions in plants. However, the role of mediator in the regulation of nicotine biosynthesis remains unknown. In this study, we firstly identify the NtMED25 through homologous analysis. NtMED25 interacts with NtMYC2s through the MD region. Interestingly, the nicotine content is decreased in the the knock-down transgenic lines of NtMED25, and the expression levels of two nicotine biosynthesis genes, NtQPT2 and NtPMT2, are also reduced when compared with that in the wild-type plants. Furthermore, NtMED25 enhances the binding of NtMYC2a/ NtMYC2b to the promoter of NtPMT2 and NtQPT2, and then facilitates the nicotine biosynthesis. Therefore, our study revealed the function of mediator in the regulation of nicotine, and provide the insight role on the transcriptional regulation of plant secondary metabolites.

Background Abscisic acid (ABA) is an important phytohormone for plant growth, development and responding to stresses such as drought, salinity, and pathogen infection. Pyrabactin Resistance 1 (PYR1)/PYR1-Like (PYL)/Regulatory Component of ABA Receptor (RCAR) (hereafter referred to as PYLs) has been identified as the ABA receptors. The PYL family members have been well studied in many plants. However, the members of PYL family have not been systematically identified at genome level in cultivated tobacco (Nicotiana tabacum) and its two ancestors. In this study, the phylogenic relationships, chromosomal distribution, gene structures, conserved motifs/regions, and expression profiles of NtPYLs were analyzed. Results We identified 29, 11, 16 PYLs in the genomes of allotetraploid N. tabacum, and its two diploid ancestors N. tomentosiformis and N. sylvestris, respectively. The phylogenetic analysis revealed that NtPYLs can be divided into three subfamilies, and each NtPYL has one counterpart in N. sylvestris or N. tomentosiformis. Based on microarray analysis of NtPYL transcripts, four NtPYLs (from subfamily II, III), and five NtPYLs (from subfamily I) are highlighted as potential candidates for further functional characterization in N. tabacum seed development, response to ABA, and germination, and resistance to abiotic stresses, respectively. Interestingly, the expression profiles of members in the same NtPYL subfamily showed somehow similar patterns in tissues at different developmental stages and in leaves of seedlings under drought stress, suggesting particular NtPYLs might have multiple functions in both plant development and drought stress response. Conclusions NtPYLs are highlighted for important functions in seed development, germination and response to ABA, and particular in drought tolerance. This work will not only shed light on the PYL family in tobacco, but also provides some valuable information for functional characterization of ABA receptors in N. tabacum. Electronic supplementary material The online version of this article (10.1186/s12864-019-5839-2) contains supplementary material, which is available to authorized users.

The biosynthesis of flavonols and anthocyanins is precisely regulated by different transcription factors in plants. WRKY11 promotes the biosynthesis of flavonoids in apple, but the molecular mechanism of WRKY11 regulating flavonols biosynthesis, and whether WRKY11 plays the same roles in other plants species remains to be further studied. Here, we cloned four NtWRKY11 genes from tobacco, which all contained the conserved WRKYGQK heptapeptide and a zinc-finger motif. The NtWRKY11b showed higher expression levels than the other NtWRKY11 genes in all the tobacco tissues examined, especially in tobacco leaves. Silencing of NtWRKY11b in tobacco leaves reduced the content of flavonols to 45.2 %-69.8 % of that in the WT plants, but overexpression of NtWRKY11b increased the flavonols content by 37.8 %-80.7 %. Transcriptome analysis revealed 8 flavonoids related differentially expressed genes (DEGs) between NtWRKY11b-OE and WT plants, among which the transcription of NtMYB12, NtFLS, NtGT5, and NtUFGT was significantly induced by posttranslational activation of NtWRKY11b with the presence of protein synthesis inhibitor, indicating a putative direct promotion of NtWRKY11b on the transcription of these flavonoids related genes. Chromatin immunoprecipitation assays further demonstrated that NtWRKY11b could bind to the promoter regions of NtMYB12, NtFLS, NtGT5, and NtUFGT to activate the transcription of these genes. Moreover, ectopic expression of NtWRKY11b also promoted the expression levels of NtCML38, NtCTL1, NtWRKY44, and NtCML37 genes, which have been shown to enhance plant resistance to various stresses. Our findings revealed the molecular mechanism of NtWRKY11b regulating flavonols biosynthesis, and provided a promising target for increasing flavonols content in tobacco.

Ciprofloxacin, a third-generation fluoroquinolones (FQs) antibiotic, is observed to increasingly pollute the environment. In this study, a three-dimensional reduced graphene oxide-attapulgite-based catalyst Fe2O3/RGO-ATP was prepared and used to analyze the degradation of ciprofloxacin in a heterogeneous Fenton reaction. The heterogeneous catalyst Fe2O3/RGO-ATP was prepared by a one-step hydrothermal method, and the samples were characterized using BET(Brunauer-Emmett-Teller) surface area, Raman spectroscopy, X-ray diffraction (XRD), Fourier infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The effect of reaction time, temperature, pH, initial concentration, H2O2 dosage and reuse time on the degradation of ciprofloxacin by the catalyst Fe2O3/RGO-ATP was investigated. The optimum conditions of degradation of ciprofloxacin are observed to be 60 &deg, C, pH 5, H2O2 concentration of 2.9724 mmol/L, and initial ciprofloxacin concentration of 50 mg/L. The catalyst could be reused several times with a decline in catalytic capacity. Fourier-transform ion cyclotron resonance mass spectrometer (FT) was also employed to study the degradation products of ciprofloxacin in the aqueous solution. The results show that the heterogeneous catalyst Fe2O3/RGO-ATP possessed an excellent ability for the catalytic degradation of ciprofloxacin. Direct hydroxyl oxidation is noted to be the main pathway of degradation of ciprofloxacin, and no defluorination reaction is observed during the degradation process.

China has abundant reserves of magnesite, making it the world's leading source of this strategic mineral. Sparry magnesite is the main type of magnesite deposit, and is easy to exploit. It occurs mainly as the sedimentary-metamorphic type. Production is centred on eastern Liaoning Province, where a world-class large to super large magnesite ore processing and production facility has been developed. Hydrothermal metasomatic deposits, associated with ultramafic complexes and eluvial deposits produced by weathering, are two other important types found in China. The Western section of the Bangonghu-Nujiang metallogenic belt is an important target region for prospecting lake-sedimentary magnesite deposits. Based on a systematic analysis of material from 62 magnesite production areas, this study investigated the metallogeny of magnesite and delineated 13 magnesite metallogenic belts. Maps were produced showing metallogenic regularities in magnesite deposits, the metallogenic system of the magnesite deposits, and the distribution of the metallogenic belts of Chinese magnesite deposits. It provides a theoretical basis for forecasting the location of potential magnesite resources in China. Finally, it explores some key scientific issues, including the formation processes of ultra magnesite ore-concentrated areas, and their sources of magnesium.

This paper investigated the effects of pear jam with different calcium salt, calcium chloride, calcium acetate and calcium lactate on the properties of jam. The rheological, physicochemical and electronic nose of jam were studied. The results showed that every calcium salts added could change in the rheology of the jam. The rheology viscosity order in jam was calcium chloride > calcium acetate > calcium lactate. Also, the differences in the soluble solids, VC, color and odors were observed among the jam samples in the experiment. The addition of calcium salts made the content of soluble solids and VC increased, titratable acidity, color and odors couid be retained. The use of calcium salt improved quality of pear jam. They would improve consumer acceptance.

An effective method for Agrobacterium tumefaciens inhibition using silica nanoparticles (NPs) as the carrier and melittin as the antibacterial drug is developed. The diameters of the inhibition zones of A. tumefaciens treated with different concentrations of melittin-conjugated silica NPs, pure silica NPs, gentamicin and free melittin are determined. The results indicate that the pure silica NPs have no impact on A. tumefaciens. The melittin-conjugated silica NPs have strong antibacterial activity against A. tumefaciens. In addition, the antibacterial activity of the melittin-conjugated silica NPs is dose dependent. The diameter of the inhibition zone caused by the melittin-conjugated silica NPs is almost the same as the positive control. Compared with the free drug molecules, silica NPs as an ideal carrier can gather a large number of drug molecules on their surface so as to greatly enhance the antibacterial activity.

Sludge Concentration (MLSS) is one of major parameters for operation of Anoxic/Aerobic-Membrane Bioreactors（A/O-MBR）and it influences the removal efficiency of pollutants and the rate of membrane fouling as well. This paper focuses on the effects of different MLSS on the treatment of domestic wastewater, the quantity and composition of extracellular polymeric substance (EPS), and the variation of the rate of membrane fouling. It also includes a preliminary analysis of the correlation between EPS and membrane fouling to provide reference for future studies of the mechanism of membrane fouling.

To investigate the protective effects and the possible molecular mechanisms of chlorogenic acid on H2O2-induced dysfunction and apoptosis in human umbilical vein endothelial cells (HUVECs). HUVECs were divided into three groups: H2O2groups (0, 5, 10, 20, 50mM), chlorogenic acid (100nmol/L) groups and atorvastatin (10μmol/L) groups. The eNOS mRNA expression was measured by RT-PCR. The content of NO in the supernatant was detected by the nitrate reductase assay. Cells activity was evaluated by the MTT assay. The level of reactive oxygen species (ROS) in cells was measured using H2DCF-DA as a fluorescence probe. Results demonstrated that H2O2caused a significant down-regulation of eNOS mRNA expression and decreased the secretion of NO in a dose-dependent manner compared with the control group. Furthermore, H2O2 induced cell apoptosis, increased ROS accumulation. Nevertheless, these effects of H2O2could be blocked by chlorogenic acid in chlorogenic acid pretreatment groups. CONCLUSION:chlorogenic acid can inhibite H2O2-induced dysfunction and apoptosis in HUVECs, which may be related to its effects on suppressing oxidative stress, up-regulating eNOS pathway. These results suggest the usefulness of chlorogenic acid particularly in the treatment of cardiovascular disease.

Based on fillers theory and traditional A/O-MBR theory, anoxic/aerobic hybrid membrane bioreactor system (A/O-HMBR for short) was modified by adding suspended biological fillers in one of the aerobic tanks of the traditional A/O-MBR, in which the filling ratio of fillers was 8%. The thesis mainly studies the nitrogen removal effect in the A/O-HMBR system when the main influence parameters, such as influent C/N(5,7,10), aeration intensity(15m3/h,20m3/h,25m3/h) and HRT(5h,8h,11h), were changed.The experimental results show that when HRT was 8h, C/N was 7, and aeration intensity was 20m3/h, TN removal effect was best.

Drought is one of the most severe forms of abiotic stresses that threaten the survival of plants, including crops. In turn, plants dramatically change their physiology to increase drought tolerance, including reconfiguration of proteomes. Here, we studied drought-induced proteomic changes in leaves of cultivated tobacco (Nicotiana tabacum), a solanaceous plant, using the isobaric tags for relative and absolute quantitation (iTRAQ)-based protein labeling technology. Of identified 5570 proteins totally, drought treatment increased and decreased abundance of 260 and 206 proteins, respectively, compared with control condition. Most of these differentially regulated proteins are involved in photosynthesis, metabolism, and stress and defense. Although abscisic acid (ABA) levels greatly increased in drought-treated tobacco leaves, abundance of detected ABA biosynthetic enzymes showed no obvious changes. In contrast, heat shock proteins (HSPs), thioredoxins, ascorbate-, glutathione-, and hydrogen peroxide (H2O2)-related proteins were up- or down-regulated in drought-treated tobacco leaves, suggesting that chaperones and redox signaling are important for tobacco tolerance to drought, and it is likely that redox-induced posttranslational modifications play an important role in modulating protein activity. This study not only provides a comprehensive dataset on overall protein changes in drought-treated tobacco leaves, but also shed light on the mechanism by which solanaceous plants adapt to drought stress.

Mianning-Dechang Himalayan REE Metallogenetic Belt in Sichuan Province lies along the western margin of the Yangtze Craton. We have conducted detailed mineralogical studies on ore minerals collected from Maoniuping and Dalucao, the two largest deposits in the belt. With optical microscope, SEM/EDS, and EPMA, three rare intermetallic minerals, i.e. , zinccopperite (Cu 2 Zn), Snbearing native copper, and Cu-bearing jupiter were found to occur in the main ore along with barite, fluorite, apatite, sulfide and bastnaesite. Since the conditions under which zinccopperite and Sn- bearing native copper formed are quite unique, finding of these minerals, for the first time in domestic REE deposits, has significant implications for the genesis of the ore deposits in which they occur. In comparison with Cu-Zn intermetallic minerals in other occurrences, we propose that the formation of this REE metallogenetic belt is associated with fast upwelling of the Himalayan magma from deep source.

The plant hormone abscisic acid (ABA) plays important roles in regulating plant growth, development, and responses to environmental stresses. Proteins in the PYR/PYL/RCAR family (hereafter referred to as PYLs) are known as ABA receptors. Since most studies thus far have focused on Arabidopsis PYLs, little is known about PYL homologs in crop plants. We report here the characterization of 21 PYL homologs (GmPYLs) in soybean. Twenty-three putative GmPYLs can be found from soybean genome sequence and categorized into three subgroups. GmPYLs interact with AtABI1 and two GmPP2Cs in diverse manners. A lot of the subgroup I GmPYLs interact with PP2Cs in an ABA-dependent manner, whereas most of the subgroup II and III GmPYLs bind to PP2Cs in an ABA-independent manner. The subgroup III GmPYL23, which cannot interact with any of the tested PP2Cs, differs from other GmPYLs. The CL2/gate domain is crucial for GmPYLs-PP2Cs interaction, and a mutation in the conserved proline (P109S) abolishes the interaction between GmPYL1 and AtABI1. Furthermore, the ABA dependence of GmPYLs-PP2Cs interactions are partially correlated with two amino acid residues preceding the CL2/gate domain of GmPYLs. We also show that GmPYL1 interacts with AtABI1 in an ABA-dependent manner in plant cells. Three GmPYLs differentially inhibit AtABI1 and GmPP2C1 in an ABA-dependent or -enhanced manner in vitro. In addition, ectopically expressing GmPYL1 partially restores ABA sensitivity of the Arabidopsis triple mutant pyr1/pyl1/pyl4. Taken together, our results suggest that soybean GmPYLs are ABA receptors that function by interacting and inhibiting PP2Cs.

Through bioassay-guided fractionation, the EtOAc extract of a culture broth of the endophytic fungus Phoma species ZJWCF006 in Arisaema erubescens afforded a new α-tetralone derivative, (3S)-3,6,7-trihydroxy-α-tetralone (1), together with cercosporamide (2), β-sitosterol (3), and trichodermin (4). The structures of compounds were established on the basis of spectroscopic analyses. Compounds 1, 2, and 3 were obtained from Phoma species for the first time. Additionally, the compounds were subjected to bioactivity assays, including antimicrobial activity, against four plant pathogenic fungi (Fusarium oxysporium, Rhizoctonia solani, Colletotrichum gloeosporioides, and Magnaporthe oryzae) and two plant pathogenic bacteria (Xanthomonas campestris and Xanthomonas oryzae), as well as in vitro antitumor activities against HT-29, SMMC-772, MCF-7, HL-60, MGC80-3, and P388 cell lines. Compound 1 showed growth inhibition against F. oxysporium and R. solani with EC50 values of 413.22 and 48.5 μg/mL, respectively. Additionally, compound 1 showed no cytotoxicity, whereas compound 2 exhibited cytotoxic activity against the six tumor cell lines tested, with IC50 values of 9.3 ± 2.8, 27.87 ± 1.78, 48.79 ± 2.56, 37.57 ± 1.65, 27.83 ± 0.48, and 30.37 ± 0.28 μM, respectively. We conclude that endophytic Phoma are promising sources of natural bioactive and novel metabolites.

The effects of serum on the morphological plasticity exhibited by pituicytes in explant cultures of the neurohypophysis of adult rats have been examined. Cultured pituicytes are normally nonstellate, protoplasmic, amorphous cells (< 25% are stellate with a distinct cell body and phase bright processes). After incubation (90 min) of pituicyte cultures in a HEPES buffered salt solution (HBSS) supplemented with isoproterenol or forskolin, the fraction of stellate pituicytes significantly increased. The increase in the fraction of stellate cells induced by isoproterenol was not reversed by subsequent incubation in isoproterenol-free HBSS for 90 min. In contrast, after stellation was induced in cultures by exposure to forskolin (90 min), the fraction of stellate cells was significantly reduced if these cultures were incubated in forskolin-free, serum (0.5%) supplemented HBSS for the same duration. Serum also blocked the increase in the fraction of stellate pituicytes induced by forskolin. These experiments suggest that serum components may have a significant role in controlling the plasticity of neuroglial relations in the neurohypophysis previously demonstrated in vivo.