Search

Purpose Previously, we showed that lactate promoted the proliferation and mobility of hepatocellular carcinoma (HCC) cells by increasing the expression of ornithine decarboxylase 1 (ODC1). In this study, we determined the relationship between ODC1 and pyruvate kinase M2 (PKM2, a key lactate metabolism enzyme), and determined the combined effects of difluoromethylornithine (DFMO; an ODC1 inhibitor) and compound 3k (a PKM2 inhibitor) on HCC cells. Methods First, the relationship between PKM2 and ODC1 was analyzed using Western blotting, Cell Counting Kit (CCK)-8 assays, transwell assays, bioinformatics, quantitative real-time fluorescent PCR (qRT-PCR), and immunohistochemical staining. Thereafter, the ODC1 inhibitor DFMO and the PKM2 inhibitor compound 3k were employed. Their combined effects on HCC cell proliferation and mobility were evaluated via CCK-8 assay, flow cytometry, a subcutaneous xenograft tumor model in mice, wound healing assays, and transwell assays. Additionally, the effects of DFMO and compound 3k on the epithelial–mesenchymal transition phenotype and the AKT/GSK-3β/β-catenin pathway were explored using Western blotting and immunofluorescence. Results PKM2 knockdown significantly decreased the ODC1 expression, and the proliferation and invasion of HCC cells, while ODC1 overexpression reversed the inhibitory effects of PKM2 knockdown. Similarly, inhibition of ODC1 also decreased the expression of PKM2 via reducing the c-myc-induced transcription. PKM2 was co-expressed with ODC1 in HCC samples, while simultaneously upregulated PKM2 and ODC1 led to the poorest survival outcome. DFMO and compound 3k synergistically inhibited HCC cell proliferation, induced apoptosis, and suppressed cell mobility, as well as the EMT phenotype and the AKT/GSK-3β/β-catenin pathway. The AKT activator SC79 reversed the inhibitory effects. Conclusion PKM2/ODC1 are involved in a positive feedback loop. The simultaneous inhibition of ODC1 and PKM2 using DFMO and compound 3k exerts synergistic effects against HCC cells via the AKT/GSK-3β/β-catenin pathway. Thus, DFMO combined with compound 3k may be a novel effective strategy for treating HCC.

Endophytic fungi have the potential to enhance plant resistance to various stresses and promote the ecological adaptation of the hosts. To evaluate the effects of the riparian endophytes on rice seedlings to flooding tolerance, here we screened out two endophytes from the plant Myricaria laxiflora growing in the Yangtze River zone. Through morphological characteristics and rDNA ITS (internal transcriber region) sequence, the two strains were respectively identified as Aspergillus fumigatus and Chaetomium globosum. Metabolites derived from both fungi were capable of increasing tolerance to flooding. Systematic separation and purification coupled to bioassays revealed that two natural antioxidants, Z-N-4-hydroxystyryl formamide (NFA) and chaetoglobosin A (CheA), were effective for alleviating flooding stress. Both NFA and CheA inhibited the production of factors such as malondialdehyde, superoxide dismutase, ethanol dehydrogenase, and NADPH oxidase that are associated with oxidative stress induced by flooding. Gene expression analyses of NADPH oxidase families indicated that OsRbohB could be involved in conferring flooding tolerance mediated by the two natural antioxidants. These findings contribute to understanding the role of the natural antioxidants in riparian endophytic fungi, and providing a basis for improvement of flooding tolerance of rice and other crop plants through the antioxidants of the fungal endophytes.

The huge economic loss of citrus fruit after harvest called for safe and efficient preservatives, as chemically synthesized agents threatened the environment and human health. Herein a biocontrol fungus Chaetomium globosum QY-1 near the orchard in riparian area was identified to have antimicrobial, antioxidant and tyrosinase inhibition activity, which meets the requirements of an ideal preservative. Metabolite profiling based on bioassay-guided fractionation was carried out, and eight polyketones were determined by MS and NMR. The most abundant CheA exhibited strong inhibition to Penicillium digitatum, the main pathogen caused citrus fruit rot. Among these metabolites, Epicoccone and Epicoccolide B showed higher antioxidant activity, while Epicoccone and CheA had higher tyrosinase inhibitory activity. All the activities were close to or even better than the positive control (Vc; glutathione; Vc and arbutin; Bellkute), implying that the metabolites of C. globosum had comprehensive effects as natural preservatives.

Penicillium oxalicum has been used as a biocontrol fungus in agriculture for many years, but the antimicrobial substances are still uncertain. Herein, we isolated a linear peptide named Sanxiapeptin in the culture broth of Penicillium oxalicum SG-4 collecting from the Three Gorges riparian zone. Sanxiapeptin exhibited potent inhibitory effect on citrus green mold Penicillium digitatum, the main fungi responsible for postharvest decay. Sanxiapeptin was elucidated as composing of five amino acids, which were β-amino-α-methoxybutyric acid (Amoba), N-Me- l -Thr, d -Thr, N-Me- l -Val and l -Ser. By analyzing three chemically synthesized oligopeptides with similar structures, we found that the first amino acid of Amoba was crucial to the antifungal activity, as was the methylation of peptide bond. Sanxiapeptin may act as an antimicrobial agent by affecting the function of cell membranes or walls. The antimicrobial spectrum, safety and stability analysis supported that Sanxiapeptin was a promising antifungal agent for citrus preservation.

Poly(diallyldimethylammonium chloride, PDDA)-functionalized reduced graphene oxide (rGO) is explored as a catalyst support material for the first time. Pd nanoparticles are in situ deposited on rGO sheets due to electro-static attraction. Pd/rGO catalysts with nanometer particle size and high dispersion, are synthesized by a simple aqueous phase reduction method. The catalysts are characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impendence spectroscopy. The results indicate that Pd nanoparticles with an average size of 2.0 nm are uniformly dispersed on the graphene sheets. The prepared Pd/rGO catalyst displayed a dramatically higher electrochemical surface area, and higher and more stable activity towards methanol oxidation compared to commercial Pd/C in alkaline media, and is believed to be a promising catalyst for methanol-fed alkaline fuel cells.

Pd/C catalyst with small particle size, high dispersion and high wt.% of metal was in situ synthesized by a simple aqueous phase reduction method. Poly(diallyldimethylammonium chloride) PDDA-functionalized carbon black was used as a support material for the in situ deposition of Pd nanoparticles by means of electrostatic attraction. The catalysts were characterized by transmission electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy, cyclic voltammetry and rotating disc electrode test. The results indicated that Pd nanoparticles with an average size of 2.09 nm were uniformly dispersed onto the carbon black with a metal weight percentage of ∼30 wt.%. The prepared Pd/C catalyst has showed remarkably larger electrochemical surface area and higher and more stable ORR activity as compared to commercial Pd/C catalyst and commercial Pt/C catalyst in alkaline media, which was believed to be a promising alternative to Pt-based catalyst used in alkaline fuel cell.

Buxus ichangensis is a rare shrub specifically distributed along the banks of the Yangtze River in Three Goreges Reservoir area. In order to bring a basis for population reconstruction and ex situ conservation, we surveyed the flood-tolerance capacity of B. ichangensis together with its close species, Buxus microphylla. The results showed that B. ichangensis plants were more tolerant to waterlogging stress. Through further investigation of the physiological responses of 2 Buxus species, we supposed a possible mechanism for flooding adaption that physiological factors, especially photosynthesis rate, stomatal conductance, chlorophyll content and root livingness, were highly correlated with flooding-tolerance.

A simple and cost-effective gel-casting technique has been developed to fabricate phosphotungstic acid (HPW) supported on mesoporous silica (MCM-41) electrolyte membrane (HPW/MCM-41) for direct methanol fuel cells (DMFCs). The effect of HPW loading on the stability of MCM-41 structure has been analyzed by small-angle X-ray scattering (SAXS), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) techniques. In particular, the effect of solid state loading and HPW loading on the microstructure, water gain ratio, swelling ratio and conductivity of the HPW/MCM-41 membranes have been studied in detail. The results showed that a large proportion of loaded HPW is anchored in the mesoporous silica matrix, forming an effective proton conduction pathway. The results also showed that the composite membrane can operate successfully at temperatures below 200 °C for a long duration, based on the TGA curve of organic network formed during the gelation stage. The single cell assembled from HPW/MCM-41 membrane with 65 wt.% HPW loading gives a peak power of 101 mW cm −2 in methanol/air at 150 °C without any humidification.

Three new steroidal compounds with polyhydroxy groups, tupisteroide A-C (1-3), were obtained from the roots of Tupistra chinensis, together with one known compound (4) that was isolated from this plant for the first time. The structures of tupisteroide A-C were determined on the basis of one- and two-dimensional NMR spectroscopy, including (1) H-(1) H Correlation Spectroscopy, Heteronuclear Multiple Bond Correlation, and Heteronuclear Single Quantum Coherence experiments. The isolated compounds were evaluated for their cytotoxic activities against A549, HepG2, and CaSki cancer cell lines in vitro. Among them, compounds 1, 2, and 4 did not show significant inhibitory activity, but compound 3 showed cytotoxicity against A549 cancer cell lines with IC(50) values of 25.0 μM.

ARF-GEFs are a family of guanine-nucleotide exchange factors catalyzing the exchange of GDP for GTP on ADP-ribosylation factor. Large ARF-GEFs are highly conserved in all eukaryotes. It is an important regulator in both membrane dynamics and protein trafficking. Significant progress has been made in elucidating the structure, subcellular localization, and physiological functions of ARF-GEFs as a hot topic of cell biology recently. In this review, the character-istics and distribution of ARF-GEFs in different species, and recent research progress of ARF-GEFs and their regulation system are summarized.

Objectives Reactive oxygen species can induce cell apoptosis, and oxidative stress has been implicated in a variety of neurodegenerative disorders. Tomatine, which is a naturally occurring steroidal glycoalkaloid isolated from Solanum cathayanum, has shown potent anti-oxidant properties. Methods In this study, we used the SH-SY5Y cell line as an in vitro model and investigated the protective effect of tomatine against hydrogen peroxide (H2O2)-induced neurotoxicity in SH-SY5Y cells. Key findings Tomatine might inhibit the release of cellular lactate dehydrogenase, increase anti-oxidant enzyme activity and glutathione content, reverse the downregulated protein expression of the brain-derived neurotrophic factor (BDNF), inhibit expression of Bax and activations of caspase-3 and caspase-9 in H2O2-induced SH-SY5Y cells. Conclusions Tomatine exerted beneficially neuroprotective effect on H2O2-induced SH-SY5Y cells, mainly enhancing intracellular anti-oxidant enzyme activity and BDNF expression, inhibiting H2O2-induced oxidative stress as well as expression of Bax and activations of caspase-3 and caspase-9, alleviating H2O2-induced SH-SY5Y cell injury and cell death.

Two new spirostanols and a new furostanol, reinocarnoside A (1), B (2) and C (3), were isolated from the roots of Reineckia carnea, together with two known compounds, (25S)-1β,3β,4β-trihydroxyspirostan-5β-yl-O-β-D-glucopyranoside (4), kitigenin-5β-O-β-D-glucopyranoside (5). The structures of three new compounds were elucidated by spectroscopic methods including 1-D NMR, 2-D NMR and MS spectrums, and their anticancer activities were evaluated by MTT method.

Three new steroidal compounds with polyhydroxy groups, tupisteroide A-C (1-3), were obtained from the roots of Tupistra chinensis, together with one known compound (4) that was isolated from this plant for the first time. The structures of tupisteroide A-C were determined on the basis of one- and two-dimensional NMR spectroscopy, including (1) H-(1) H Correlation Spectroscopy, Heteronuclear Multiple Bond Correlation, and Heteronuclear Single Quantum Coherence experiments. The isolated compounds were evaluated for their cytotoxic activities against A549, HepG2, and CaSki cancer cell lines in vitro. Among them, compounds 1, 2, and 4 did not show significant inhibitory activity, but compound 3 showed cytotoxicity against A549 cancer cell lines with IC(50) values of 25.0 μM.

ARF-GEFs are a family of guanine-nucleotide exchange factors catalyzing the exchange of GDP for GTP on ADP-ribosylation factor. Large ARF-GEFs are highly conserved in all eukaryotes. It is an important regulator in both membrane dynamics and protein trafficking. Significant progress has been made in elucidating the structure, subcellular localization, and physiological functions of ARF-GEFs as a hot topic of cell biology recently. In this review, the character-istics and distribution of ARF-GEFs in different species, and recent research progress of ARF-GEFs and their regulation system are summarized.

The effect of silver ions on the water dissociation of bipolar membranes was first investigated in this paper. To do this, the bipolar membranes were prepared by immersing the anion exchange layers in an AgNO3 solution and then coating a solution of sulfonated polyphenylene oxide (SPPO) on the anion exchange layers. XPS and AES observations indicated that silver at the intermediate layer was in the form of AgCl. The experimental results proved that AgCl has an excellent catalytic function for water dissociation in terms of I-V curves, and the quantity of AgCl played an important role in the behavior of a bipolar membrane. The bipolar membranes with gelatin and the gelatin doped with silver as a catalytic layer were also prepared in the same way, and their I-V behavior and the water dissociation pilot tests were also investigated. The experimental results showed that in the case of gelatin alone, the voltage drop increased slightly at high gelatin concentrations, due mainly to the steric effect and electrostatic interaction, but decreased at low gelatin concentrations due to the hydrophilicity. However, when gelatin was doped with AgCl, the bipolar membranes have an appreciable improvement in both stability and catalytic function, in comparison with those prepared from silver or gelatin.