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Background: Streptomycetes from the rhizospheric soils are a rich resource of novel secondary metabolites with various biological activities. However, there is still little information related to the isolation, antimicrobial activity and biosynthetic potential for polyketide and non-ribosomal peptide discovery associated with the rhizospheric streptomycetes of Panax notoginseng. Thus, the aims of the present study are to (i) identify culturable streptomycetes from the rhizospheric soil of P. notoginseng by 16S rRNA gene, (ii) evaluate the antimicrobial activities of isolates and analyze the biosynthetic gene encoding polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs) of isolates, (iii) detect the bioactive secondary metabolites from selected streptomycetes, (iv) study the influence of the selected isolate on the growth of P. notoginseng in the continuous cropping field. This study would provide a preliminary basis for the further discovery of the secondary metabolites from streptomycetes isolated from the rhizospheric soil of P. notoginseng and their further utilization for biocontrol of plants. Results: A total of 42 strains representing 42 species of the genus Streptomyces were isolated from 12 rhizospheric soil samples in the cultivation field of P. notoginseng and were analyzed by 16S rRNA gene sequencing. Overall, 40 crude cell extracts out of 42 under two culture conditions showed antibacterial and antifungal activities. Also, the presence of biosynthesis genes encoding type I and II polyketide synthase (PKS I and PKS II) and nonribosomal peptide synthetases (NRPSs) in 42 strains were established. Based on characteristic chemical profiles screening by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD), the secondary metabolite profiles of strain SYP-A7257 were evaluated by High Performance Liquid Chromatography-High Resolution Mass Spectrometry (HPLC-HRMS). Finally, four compounds actinomycin X2 (F1), fungichromin (F2), thailandin B (F7) and antifungalmycin (F8) were isolated from strain SYP-A7257 by using chromatography techniques, UV, HR-ESI-MS and NMR, and their antimicrobial activities against the test bacteria and fungus were also evaluated. In the farm experiments, Streptomyces sp. SYP-A7257 showed healthy growth promotion and survival rate improvement of P. notoginseng in the continuous cropping field. Conclusions: We demonstrated the P. notoginseng rhizospheric soil-derived Streptomyces spp. distribution and diversity with respect to their metabolic potential for polyketides and non-ribosomal peptides, as well as the presence of biosynthesis genes PKS I, PKS II and NRPSs. Our results showed that cultivatable Streptomyces isolates from the rhizospheric soils of P. notoginseng have the ability to produce bioactive secondary metabolites. The farm experiments suggested that the rhizospheric soil Streptomyces sp. SYP-A7257 may be a potential biological control agent for healthy growth promotion and survival rate improvement of P. notoginseng in the continuous cropping field. [ABSTRACT FROM AUTHOR]

In this Letter, we study a nonlocal vector nonlinear Schrödinger (NVNLS) equation with self-induced parity-time-symmetric potential. We construct the N -fold Darboux transformation in terms of compact determinant forms. Starting from the non-vanishing background, we give the general solution of spectral problem, which allows us to derive many different types of exact analytical solutions of the NVNLS equation, like the breathers, dark and anti-dark solitons. With three-component case as an example, we display three types of two-soliton elastic collision behaviors: breather and dark soliton, breather and anti-dark soliton, dark soliton and anti-dark soliton. [ABSTRACT FROM AUTHOR]

Background: Per- and polyfluoroalkyl substances (PFAS) are known environmental contaminants with immunosuppressive properties. Their connection to rheumatoid arthritis (RA), a condition influenced by the immune system, is not well studied. This research explores the association between PFAS exposure and RA prevalence. Methods: This research utilized data from the NHANES, encompassing a sample of 10,496 adults from the 2003–2018 cycles, focusing on serum levels of several PFAS. The presence of RA was determined based on self-reports. This study used multivariable logistic regression to assess the relationship between individual PFAS and RA risk, adjusting for covariates to calculate odds ratios (ORs). The combined effects of PFAS mixtures were evaluated using BKMR, WQS regression, and quantile g-computation. Additionally, sex-specific associations were explored through stratified analysis. Results: Higher serum PFOA (OR = 0.88, 95% CI: 0.79, 0.98), PFHxS (OR = 0.91, 95% CI: 0.83, 1.00), PFNA (OR = 0.87, 95% CI: 0.77, 0.98), and PFDA (OR = 0.89, 95% CI: 0.81, 0.99) concentration was related to lower odds of RA. Sex-specific analysis in single chemical models indicated the significant inverse associations were only evident in females. BKMR did not show an obvious pattern of RA estimates across PFAS mixture. The outcomes of sex-stratified quantile g-computation demonstrated that an increase in PFAS mixture was associated with a decreased odds of RA in females (OR: 0.76, 95% CI: 0.62, 0.92). We identified a significant interaction term of the WQS*sex in the 100 repeated hold out WQS analysis. Notably, a higher concentration of the PFAS mixture was significantly associated with reduced odds of RA in females (mean OR = 0.93, 95% CI: 0.88, 0.98). Conclusions: This study indicates potential sex-specific associations of exposure to various individual PFAS and their mixtures with RA. Notably, the observed inverse relationships were statistically significant in females but not in males. These findings contribute to the growing body of evidence indicating that PFAS may have immunosuppressive effects. [ABSTRACT FROM AUTHOR]

In this paper, via the limit technique of long wave, the N-order rational solution of the (2+1)-dimensional B-type Kadomtsev–Petviashvili (BKP) equation is derived from the N-soliton solution. In particular, the bright–dark M-lump solution can be obtained from resulting N-order rational solution. This kind of lump wave in BKP equation exhibits the one-peak-one-valley structure which is different from that in KPI equation. In addition, graphical illustration presents the collision dynamics of multi-bright–dark lump waves. [ABSTRACT FROM AUTHOR]

A total of 58 fungal isolates, belonging to 24 genera, were obtained from the leaves, stems and roots of Ginkgo biloba L.. Among them, one endophytic fungal strain, Penicillium cataractum SYPF 7131, displayed the strongest antibacterial activity. Four new compounds ( 1 – 4) were isolated from the strain fermentation broth together with four known compounds ( 5 – 8) . These structures were determined on the basis of 1D and 2D NMR and [Rh 2 (OCOCF 3 ) 4 ]-induced electronic circular dichroism (ECD) spectroscopic analyses. All the isolated compounds were screened for their in vitro antimicrobial activities. Compound 3 and 4 showed moderate inhibitory activity against Staphylococcus aureus . Compound 7 exhibited significant inhibitory activity against S. aureus with MIC value of 10 μg/mL. Further, the in silico molecular docking studies of the active compounds was used to explore the binding interactions with the active site of filamentous temperature-sensitive protein Z (FtsZ) from Staphylococcus aureus . The docking results revealed that compounds 3 , 4 and 7 showed high binding energies, strong H-bond interactions and hydrophobic interactions with FtsZ from S. aureus validating the observed antimicrobial activity. Based on antimicrobial activities and docking studies, compounds 3 , 4 and 7 were identified as promising antimicrobial lead molecules. [ABSTRACT FROM AUTHOR]

In this Letter, the Darboux transformation is first applied to the defocusing Sasa–Satsuma equation which describes the propagation dynamics of ultrashort light pulses in the normal dispersion regime of optical fibers. The N -fold iterative transformation is expressed in terms of the determinants. This transformation enables us to construct explicit analytical dark soliton solutions from non-vanishing background. In illustration, the single-dark soliton solution is presented from the once-iterated formula. [ABSTRACT FROM AUTHOR]

Microfluidic paper-based analytical devices (μPADs) have a significant potential in developing portable and disposable point-of-care testing (POCT). Herein, a facile, rapid, cost-effective and environment friendly strategy for μPADs fabrication is proposed. Specifically, the substrate paper was hydrophobized by coating with trimethoxysilane (TOS), and then the selected area was hydrophilized by treating with surfactant. The whole fabrication process was implemented within 7 min, with no need for complex pre-treatment, high-temperature and special equipment. As a proof-of-concept application, the as-prepared μPAD was applied to determination of the glucose content in human serum samples. The results agreed well with those obtained by a glucometer. We believe that the μPADs fabrication method proposed here could provide a facile, rapid and low-cost reference for other related studies. [ABSTRACT FROM AUTHOR]

• SDH_1927 has the highest specific activity (56.72 ± 1.2 U/mg) among the eight L-sorbose dehydrogenases. • The 2-KGA production can be significantly increase by PMS under the condition of avoiding light. • The product 2-KGA could inhibit SDH activity by competing for the same hydrogen bonding sites with the substrate of L-sorbose. • The cell-recycling catalysis system is proposed to convert L-sorbose to 2-KGA, with the yield of 80.12 g/L and the productivity of 6.68 g/L/h. There are five L-sorbose dehydrogenases (SDH_2764, SDH_2744, SDH_0718, SDH_1927, SDH_0337) in Ketogulonicigenium vulgare SPU B805 and three L-sorbose dehydrogenases (SDH_02251, SDH_02271, SDH_P100164) in K. robustum SPU_B003, which play essential roles in the classical two-step fermentation for 2-keto-L-gulonic acid (2-KGA, the precursor of vitamin C) synthesis. In this work, the above eight SDH enzymes were cloned and purified, and their optimal pH values and reaction temperatures, kinetic properties (K m and K cat), thermal stabilities, substrate spectra, and effects of metal ions were determined. Eight SDH-harboring recombinant E.coli strains were verified to be capable to catalyze L-sorbose to 2-KGA. Additionally, the molecular docking results showed that the product 2-KGA could inhibit SDH activity by competing for the same hydrogen bonding sites with substrate L-sorbose. Finally, a novel and efficient whole-cell recycling catalysis system to overcome the product inhibition was proposed, the yield of 2-KGA reached up to 80.12 g/L with the productivity of 6.68 g/L/h. The results provide a promising prospect for selection and modification sorbose dehydrogenase for construction a one-step biotransformation system of 2-KGA. [Display omitted] [ABSTRACT FROM AUTHOR]

Since synovial hypoxic microenvironment significantly promotes the pathological progress of rheumatoid arthritis (RA), hypoxia-inducible factor 1 (HIF-1) has been emerged as a promising target for the development of novel therapeutic agents for RA treatment. In this study, we designed and synthesized a series of diaryl substituted isoquinolin-1(2H)-one derivatives as HIF-1 signaling inhibitors using scaffold-hopping strategy. By modifying the substituents on N -atom and 6-position of isoquinolin-1-one, we discovered compound 17q with the most potent activities against HIF-1 (IC 50 = 0.55 μM) in a hypoxia-reactive element (HRE) luciferase reporter assay. Further pharmacological studies revealed that 17q concentration-dependently blocked hypoxia-induced HIF-1α protein accumulation, reduced inflammation response, inhibited cellular invasiveness and promoted VHL-dependent HIF-1α degradation in human RA synovial cell line. Moreover, 17q improved the pathological injury of ankle joints, decreased angiogenesis and attenuated inflammation response in the adjuvant-induced arthritis (AIA) rat model, indicating the promising therapeutic potential of compound 17q as an effective HIF-1 inhibitor for RA therapy. [Display omitted] • A series of isoquinolinone derivatives were designed, synthesized and evaluated for their inhibition on HIF-1 signaling. • 17q showed enhanced inhibition on HIF-1 signaling than its parent compound in inflammatory synovial cell line. • 17q improved the pathological injury of ankle joints, decreased angiogenesis and attenuated the inflammation in vivo. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nutrients are recovered via selective separation plus induced precipitation. • A novel FCDI-MAFC coupled system for simultaneous nutrients recovery is proposed. • A urea solution with 99.7% of purity is obtained after ionic separation. • Artificial phosphate ore with 98.2% of phosphate content is produced. • Struvite accounts for more than 90% of mass weight in artificial phosphate ores. Both the sustainable development and environmental protection urge a demand of new paradigm to recover high-quality nutrients from source-separated urine, but the simultaneous recovery of phosphorus and nitrogen is difficult due to the complex composition. Herein, a coupled system consisting of a flow-electrode capacitive desalination and magnesium-air fuel cell (FCDI-MAFC) was proposed to accomplish electrochemical selective separation plus induced precipitation. The results showed that ionic species in urine were effectively separated from the non-ionic components to generate a urea solution with purity up to 99.7%. Ionic species were converted into artificial phosphate ores (APOs) with a phosphate content of 98.2%. The mass proportion of struvite in the APOs exceeded 90%. The energy consumption also decreased by 13% over five batches of operation. The overall results provide a novel method for the electrochemical selective separation and recovery of high-quality nutrients from complex wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • A one-step fermentation system was established in P. putida KT2440. • Enhanced electron transport efficiency increased the 2-KGA production. • The provision of a stable catalytic environment can enhance 2-KGA production. • Multi-strategy leads to a 15.48-fold enhancement in one-step fermentation. 2-KGA, a precursor for the synthesis of Vitamin C, is currently produced in China utilizing the "two-step fermentation" technique. Nevertheless, this method exhibits many inherent constraints. This study presents a comprehensive metabolic engineering strategy to establish and optimize a one-step 2-KGA fermentation process from D-sorbitol in Pseudomonas putida KT2440. In general, the endogenous promoters were screened to identify promoter P1 for subsequent heterologous gene expression in KT2440. Following the screening and confirmation of suitable heterologous gene elements such as sldh , sdh , cytc 551, pqq AB, and irr E, genetic recombination was performed in KT2440. In comparison to the initial achievement of expressing only sldh and sdh in KT2440, a yield of merely 0.42 g/L was obtained. However, by implementing four metabolic engineering strategies, the recombinant strain KT20 exhibited a significant enhancement in its ability to produce 2-KGA with a remarkable yield of up to 6.5 g/L – representing an impressive 15.48-fold improvement. [ABSTRACT FROM AUTHOR]

Glial glutamate transporter 1 (GLT‐1) plays a vital role in the induction of brain ischemic tolerance (BIT) by ischemic preconditioning (IPC). However, the mechanism still needs to be further explained. The aim of this study was to investigate whether peroxisome proliferator‐activated receptor gamma (PPARγ) participates in regulating GLT‐1 during the acquisition of BIT induced by IPC. Initially, cerebral IPC induced BIT and enhanced PPARγ and GLT‐1 expression in the CA1 hippocampus in rats. The ratio of nuclear/cytoplasmic PPARγ was also increased. At the same time, the up‐regulation of PPARγ expression in astrocytes in the CA1 hippocampus was revealed by double immunofluorescence for PPARγ and glial fibrillary acidic protein. Then, the mechanism by which PPARγ regulates GLT‐1 was studied in rat cortical astrocyte‐neuron cocultures. We found that IPC [45 min of oxygen glucose deprivation (OGD)] protected neuronal survival after lethal OGD (4 h of OGD), which usually leads to neuronal death. The activation of PPARγ occurred earlier than the up‐regulation of GLT‐1 in astrocytes after IPC, as determined by western blot and immunofluorescence. Moreover, the preadministration of the PPARγ antagonist T0070907 or PPARγ siRNA significantly attenuated GLT‐1 up‐regulation and the neuroprotective effects induced by IPC in vitro. Finally, the effect of the PPARγ antagonist on GLT‐1 expression and BIT was verified in vivo. We observed that the preadministration of T0070907 by intracerebroventricular injection dose‐dependently attenuated the up‐regulation of GLT‐1 and BIT induced by cerebral IPC in rats. In conclusion, PPARγ participates in regulating GLT‐1 during the acquisition of BIT induced by IPC. Cover Image for this issue: doi: 10.1111/jnc.14532. Open Science: This manuscript was awarded with the Open Materials Badge For more information see: https://cos.io/our-services/open-science-badges/ [ABSTRACT FROM AUTHOR]

Panax notoginseng (Burk.) F. H. Chen belongs to the Araliaceae family. It has been used by traditional Chinese people in Northeast Asia for centuries as an antidiabetic, antioxidant, antitumor agent, etc. Endophytic or rhizospheric microorganisms play key roles in plant defense mechanisms, and they are essential in the discovery of pharmaceuticals and valuable new secondary metabolites. In particular, endophytic or rhizospheric microorganisms of traditional medicinal plants. To discover valuable new secondary metabolites from rhizosphere soil Streptomyces sp. SYP-A7185 of P. notoginseng , and to explore potential bioactivities and targets of metabolites protrusive function. The metabolites were obtained via column chromatography and identified by multiple spectroscopic analyses. The antitumor, antioxidant, antibacterial, and antiglycosidases effects of isolated metabolites were tested using 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetazolium bromide (MTT), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 96-well turbidimetric, and α -glucosidase inhibitory assays. The potential antitumor targets were predicted through network pharmacological approaches. The interactions between metabolites and target were verified by molecular docking and biolayer interferometry (BLI) assay. The effects of cancer cells migration were detected through wound healing assays in A549 and MCF-7. Other cellular validation experiments including reverse transcription-quantitative PCR (RT‒qPCR) and western blotting (WB) were used to confirm the hypothesis of network pharmacology. Five different chemotypes of anthraquinone derivatives (1 – 10), including six new compounds (3 , 6 – 10), were identified from Streptomyces sp. SYP-A7185. Compounds 1 – 6 and 9 displayed moderate to strong cytotoxicity on five human cancer cell lines (A549, HepG2, MCF-7, MDA-MD-231, and MGC-803). Moreover, matrix metalloproteinase-2 (MMP2) were predicted as a potential antitumor target of metabolites 1 – 6 and 9 by comprehensive network pharmacology analysis. Later, BLI assays revealed strong intermolecular interactions between MMP2 and antitumor metabolites, and molecular docking results showed the interaction of metabolites 1 – 6 and 9 with MMP2 was dependent on the crucial amino acid residues of LEU-83, ALA-84, LEU-117, HIS-131, PRO-135, GLY-136, ALA-140, PRO-141, TYR-143, and THR-144. These results implied that metabolites (1 – 6 and 9) might inhibit cancer cell migration besides cancer cell proliferation. After that, the cell wound healing assay showed that the cell migration processes were also inhibited after the treatments of compounds 1 and 3 in A549 and MCF-7 cells. In addition, the RT‒qPCR and WB results demonstrated that the gene expression levels of MMP2 were decreased after the treatment with compounds 1 and 3 in A549 and MCF-7 cells. Besides, compound 2 displayed moderate antioxidant activity (EC 50 , 27.43 μM), compounds 3 and 6 exhibited moderate antibacterial activity, and compound 3 inhibited α -glucosidase with an IC 50 value of 13.10 μM. Anthraquinone metabolites, from rhizosphere soil Streptomyces sp. of P. notoginseng , possess antitumor, antioxidant, antibacterial, and antiglycosidase activities. Moreover, metabolites 1 and 3 inhibit cancer cells migration through downregulating MMP2. [Display omitted] • Anthraquinone metabolites from rhizosphere soil Streptomyces of Chinese herbs Panax notoginseng (Burk.) F. H. Chen were studied. • Ten anthraquinone derivatives were isolated including six new compounds. • Anthraquinones (1 – 10) from Streptomyces sp. SYP-A7185 exerted various bioactivities. • Anthraquinone metabolites 1 and 3 inhibit cancer cells migration through downregulating MMP2. [ABSTRACT FROM AUTHOR]

Highlights • Global brain ischemia caused delayed neuronal death(DND) in CA1 hippocampus in rats. • The ischemia led to GLT-1 down-regulation and p-p38 MAPK up-regulation in rats. • Lethal OGD decreased GLT-1 and increased p-p38 MAPK expression in astrocytes. • SB203580 or p38 MAPK siRNA reduced neuronal death and GLT-1 decreasing after OGD. • SB203580 alleviated the DND and GLT-1 down-regulation after brain ischemia in rats. Abstract The previous studies have shown that glial glutamate transporter-1 (GLT-1) participates in cerebral ischemic injury in rats. However, the mechanism involved remains to be elucidated. This study was undertaken to investigate whether p38 MAPK was involved in regulating GLT-1 in the process. At first, it was observed that global brain ischemia for 8 min led to obvious delayed neuronal death, GLT-1 down-regulation and p-p38 MAPK up-regulation in CA1 hippocampus in rats. Then, whether p-p38 MAPK was involved in regulating GLT-1 during cerebral ischemic injury was studied in vitro. Astrocyte-neuron co-cultures exposed to oxygen and glucose deprivation (OGD) were used to mimic brain ischemia. It was observed that lethal OGD (4-h OGD) decreased GLT-1 expression and increased p-p38 MAPK expression in astrocytes. The p-p38 MAPK protein rised from 0 min to 48 h that is the end time of the observation, and the peak value was at 12 h, which was 12.45 times of the control group. Moreover, pre-administration of p38 MAPK inhibitor SB203580 or its siRNA dose-dependently increased GLT-1 expression, and meanwhile alleviated the neuronal death induced by lethal OGD. The above results indicated that p38 MAPK signaling pathway participated in regulating GLT-1 during OGD injury in vitro. Finally, back to in vivo experiment, it was found that pre-administration of SB203580 by intracerebroventricular injection dose-dependently reversed the down-regulation of GLT-1 expression and attenuated the delayed neuronal death normally induced by global brain ischemia in CA1 hippocampus in rats. Taken together, it can be concluded that the mechanism of GLT-1 mediating cerebral ischemic injury depends on the activation of p38 MAPK. [ABSTRACT FROM AUTHOR]

Abstract A total of 180 fungal isolates, belonging to 20 genera and 47 species, were obtained from the roots, stems and leaves of Panax notoginseng. One isolate, the endophytic fungus Penicillium janthinellum SYPF 7899, displayed the strongest antibacterial activity and was studied for its production of secondary metabolites. In total, three new compounds, including rotational isomers 1a, 1b and 2 were isolated from the solid cultures of P. janthinellum , as well as eight known compounds (3 − 10). These structures were determined on the basis of 1D, 2D NMR and electronic circular dichroism (ECD) spectroscopic analyses as well as theoretical calculations. Compound 1 exhibited significant inhibitory activities against Bacillus subtilis and Staphylococcus aureus with MIC values of 15 and 18 μg/ml, respectively. The other compounds showed moderate or weak activities. In addition, morphological observation showed the rod-shaped cells of B. subtilis growing into long filaments, which reached 1.5- to 2-fold of the length of the original cells after treatment with compound 1. The coccoid cells of S. aureus exhibited a similar response and swelled to a 2-fold volume after treatment with compound 1. In silico molecular docking was explored to study the binding interactions between the compounds and the active sites of filamentous temperature-sensitive protein Z (FtsZ) from B. subtilis and S. aureus. Compound 1a, 1b and 2 showed high binding energies, strong H-bond interactions and hydrophobic interactions with FtsZ. Based on the antimicrobial activities, cellular phenotype observation and docking studies, compound 1 is considered to be a promising antimicrobial inhibitor of FtsZ. Graphical Abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

A novel 1(2), 2(18)-di seco indole diterpenoid , drechmerin H ( 1 ), was isolated from the fermentation broth of Drechmeria sp. together with a new indole diterpenoid, 2′- epi terpendole A ( 3 ), and a known analogue, terpendole A ( 2 ). Their structures were determined by HRESIMS, 1D and 2D NMR, ECD, and X-ray single crystal diffraction analyses as well as quantum chemical calculation. The abosulte configuration of terpendole A ( 2 ) was determined for the first time. Compound 1 displayed the significant agonistic effect on pregnane X receptor (PXR) with EC 50 value of 134.91 ± 2.01 nM, and its interaction with PXR was investigated by molecular docking. Meantime, a plausible biosynthetic pathway for compounds 1–3 is also discussed in the present work. [ABSTRACT FROM AUTHOR]

Previous studies have shown that intermittent hypobaric hypoxia (IH) preconditioning protected neurons survival from brain ischemia. However, the mechanism remains to be elucidated. The present study explored the role of nitric oxide (NO) in the process by measuring the expression of NO synthase (NOS) and NO levels. Male Wistar rats (100) were randomly assigned into four groups: sham group, IH + sham group, ischemia group and IH + ischemia group. Rats for IH preconditioning were exposed to hypobaric hypoxia mimicking 5000 m high-altitude (PB = 404 mmHg, PO2 = 84 mmHg) 6 h/day, once daily for 28 days. Global brain ischemia was established by four-vessel occlusion that has been created by Pulsinelli. Rats were sacrificed at 7th day after the ischemia for neuropathological evaluation by thionin stain. In addition, the expression of neuronal NOS (nNOS), inducible NOS (iNOS), and NO content in the hippocampal CA1 subfield were measured at 2nd day and 7th day after the ischemia. Results revealed that global brain ischemia engendered delayed neuronal death (DND), both nNOS and iNOS expression up-regulated, and NO content increased in the hippocampal CA1 subfield. IH preconditioning reduced neuronal injury induced by the ischemia, and prevented the up-regulation of NOS expression and NO production. In addition, L-NAME + ischemia group was designed to detect whether depressing NO production could alleviate the DND. Pre-administration of L-NAME alleviated DND induced by the ischemia. These results suggest that IH preconditioning plays a protective role by inhibiting the over expression of NOS and NO content after brain ischemia. [ABSTRACT FROM AUTHOR]

A novel method, real-time reverse transcription PCR (real-time RT-PCR) coupled with probe-melting curve analysis, has been established to detect two kinds of samples within one fluorescence channel. Besides a conventional TaqMan probe, this method employs another specially designed melting-probe with a 5′ terminus modification which meets the same label with the same fluorescent group. By using an asymmetric PCR method, the melting-probe is able to detect an extra sample in the melting stage effectively while it almost has little influence on the amplification detection. Thus, this method allows the availability of united employment of both amplification stage and melting stage for detecting samples in one reaction. The further demonstration by simultaneous detection of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) in one channel as a model system is presented in this essay. The sensitivity of detection by real-time RT-PCR coupled with probe-melting analysis was proved to be equal to that detected by conventional real-time RT-PCR. Because real-time RT-PCR coupled with probe-melting analysis can double the detection throughputs within one fluorescence channel, it is expected to be a good solution for the problem of low-throughput in current real-time PCR. [ABSTRACT FROM AUTHOR]

Ketogulonicigenium vulgare has been widely used in vitamin C two-step fermentation. Four K. vulgare strains (WSH-001, Y25, Hbe602 and SKV) have been completely genome-sequenced, however, less attention was paid to elucidate the reason for the differences in 2-KGA yield on genetic level. Here, a novel K. vulgare SPU B805 with higher 2-keto-L-gulonic acid (2-KGA) yield, was genome-sequenced to confirm harboring one circular chromosome with plasmid free. Comparative genome analyses showed that the absence of plasmid 2 was an important factor for its high 2-KGA productivity. The amino acid biosynthetic pathways in strain SPU B805 are much more complete than those in other K. vulgare strains. Meanwhile, strain SPU B805 harbored a complete PPP and TCA route, as well as a disabled EMP and ED pathway, same as to strain SKV, whereas strain WSH-001, Y25 and Hbe602 harbored complete PPP, ED, TCA pathway and a nonfunctional EMP pathway. The transcriptome of strain SPU B805 validated the carbon metabolism in cytoplasm mainly through the PPP pathway due to its higher transcriptional levels. This is the first time to elucidate the underlying mechanism for the difference in 2-KGA yield, and it is of great significance for strain improvement in the industrial fermentation. [ABSTRACT FROM AUTHOR]

The order of corresponding author was inadvertently published. Hence, the first and the second corresponding authors should be Min Zhang (hebmuzhangmin@163.com) and Jing-Ge Zhang (zhangjg001@163.com). [ABSTRACT FROM AUTHOR]

Background: 2-Keto-l-gulonic acid (2-KGA), the precursor of vitamin C, is currently produced by two-step fermentation. In the second step, l-sorbose is transformed into 2-KGA by the symbiosis system composed of Ketogulonicigenium vulgare and Bacillus megaterium. Due to the different nutrient requirements and the uncertain ratio of the two strains, the symbiosis system significantly limits strain improvement and fermentation optimization. Results: In this study, Ketogulonicigenium robustum SPU_B003 was reported for its capability to grow well independently and to produce more 2-KGA than that of K. vulgare in a mono-culture system. The complete genome of K. robustum SPU_B003 was sequenced, and the metabolic characteristics were analyzed. Compared to the four reported K. vulgare genomes, K. robustum SPU_B003 contained more tRNAs, rRNAs, NAD and NADP biosynthetic genes, as well as regulation- and cell signaling-related genes. Moreover, the amino acid biosynthesis pathways were more complete. Two species-specific internal promoters, P1 (orf_01408 promoter) and P2 (orf_02221 promoter), were predicted and validated by detecting their initiation activity. To efficiently produce 2-KGA with decreased CO2 release, an innovative acetyl-CoA biosynthetic pathway (XFP-PTA pathway) was introduced into K. robustum SPU_B003 by expressing heterologous phosphoketolase (xfp) and phosphotransacetylase (pta) initiated by internal promoters. After gene optimization, the recombinant strain K. robustum/pBBR-P1_xfp2502-P2_pta2145 enhanced acetyl-CoA approximately 2.4-fold and increased 2-KGA production by 22.27% compared to the control strain K. robustum/pBBR1MCS-2. Accordingly, the transcriptional level of the 6-phosphogluconate dehydrogenase (pgd) and pyruvate dehydrogenase genes (pdh) decreased by 24.33 ± 6.67 and 8.67 ± 5.51%, respectively. The key genes responsible for 2-KGA biosynthesis, sorbose dehydrogenase gene (sdh) and sorbosone dehydrogenase gene (sndh), were up-regulated to different degrees in the recombinant strain. Conclusions: The genome-based functional analysis of K. robustum SPU_B003 provided a new understanding of the specific metabolic characteristics. The new XFP-PTA pathway was an efficient route to enhance acetyl-CoA levels and to therefore promote 2-KGA production. [ABSTRACT FROM AUTHOR]