The Multifaceted Gene 275 Embedded in the PKS-PTS Gene Cluster Was Involved in the Regulation of Arthrobotrisin Biosynthesis, TCA Cycle, and Septa Formation in Nematode-Trapping Fungus Arthrobotrys oligospora.

The predominant nematode-trapping fungus Arthrobotrys oligospora harbors a unique polyketide synthase-prenyltransferase (PKS-PTS) gene cluster AOL_s00215g responsible for the biosynthesis of sesquiterpenyl epoxy-cyclohexenoids (SECs) that are involved in the regulation of fungal growth, adhesive trap formation, antibacterial activity, and soil colonization. However, the function of one rare gene (AOL_s00215g275 (275)) embedded in the cluster has remained cryptic. Here, we constructed two mutants with the disruption of 275 and the overexpression of 275, respectively, and compared their fungal growth, morphology, resistance to chemical stress, nematicidal activity, transcriptomic and metabolic profiles, and infrastructures, together with binding affinity analysis. Both mutants displayed distinct differences in their TCA cycles, SEC biosynthesis, and endocytosis, combined with abnormal mitochondria, vacuoles, septa formation, and decreased nematicidal activity. Our results suggest that gene 275 might function as a separator and as an integrated gene with multiple potential functions related to three distinct genes encoding the retinoic acid induced-1, cortactin, and vacuolar iron transporter 1 proteins in this nematode-trapping fungus. Our unexpected findings provide insight into the intriguing organization and functions of a rare non-biosynthetic gene in a biosynthetic gene cluster.

Modulating Activity Evaluation of Gut Microbiota with Versatile Toluquinol.

Gut microbiota have important implications for health by affecting the metabolism of diet and drugs. However, the specific microbial mediators and their mechanisms in modulating specific key intermediate metabolites from fungal origins still remain largely unclear. Toluquinol, as a key versatile precursor metabolite, is commonly distributed in many fungi, including Penicillium species and their strains for food production. The common 17 gut microbes were cultivated and fed with and without toluquinol. Metabolic analysis revealed that four strains, including the predominant Enterococcus species, could metabolize toluquinol and produce different metabolites. Chemical investigation on large-scale cultures led to isolation of four targeted metabolites and their structures were characterized with NMR, MS, and X-ray diffraction analysis, as four toluquinol derivatives (1-4) through O1/O4-acetyl and C5/C6-methylsulfonyl substitutions, respectively. The four metabolites were first synthesized in living organisms. Further experiments suggested that the rare methylsulfonyl groups in 3-4 were donated from solvent DMSO through Fenton's reaction. Metabolite 1 displayed the strongest inhibitory effect on cancer cells A549, A2780, and G401 with IC50 values at 0.224, 0.204, and 0.597 µM, respectively, while metabolite 3 displayed no effect. Our results suggest that the dominant Enterococcus species could modulate potential precursors of fungal origin and change their biological activity.

Graphene oxide-based benzimidazole-crosslinked networks for high-performance supercapacitors.

The synthesis of graphene oxide (GO)-based benzimidazole-crosslinked network (GOBIN) materials is presented. These materials are prepared by the covalent crosslinking of GO sheets using a condensation reaction between the carboxylic acid moieties on the GO surface and the o-aminophenyl end groups of 3,3'-diaminobenzidine (or 1,2,4,5-benzenetetraamine tetrahydrochloride). An efficient one-pot catalyst- and template-free synthesis was performed. The obtained porous GO-based materials possess a Brunauer-Emmett-Teller specific surface area ranging from 260 to 920 m(2) g(-1). Electrochemical testing indicates that the GOBIN materials display a specific capacitance up to 370 F g(-1) at a current density of 0.1 A g(-1) and about 90% of the original capacitance is retained after 5000 cycles at a current density of 3 A g(-1). Therefore, GOBIN materials can be employed as promising electrode materials for high-performance supercapacitors with outstanding cycling stability. Furthermore, owing to their significantly high specific surface area, these materials also show hydrogen uptake (up to 1.24 wt%, at 77 K and 1.0 bar) and carbon dioxide capture (up to 14.2 wt%, at 273 K and 1.0 bar) properties. As a result, these GO-based porous materials improve both the supercapacitor performance and gas sorption property, which demonstrate an excellent performance in the practical application of energy storage.

Supramolecular hydrogel based on graphene oxides for controlled release system.

Supramolecular hydrogel drug delivery system that composed of F127 modified small-sized graphene oxide (F127-SGO) and alpha-CD was prepared and the controlled release behavior was studied using doxorubicin hydrochloride (DOX) as a model drug. As compared with native hydrogel formed from F127 and alpha-CD, the SGO-containing hybrid hydrogel system shows multiple binding sites to load drug molecules and a more controllable release process that facilitates to tune the drug delivery system. These properties make the supramolecular hydrogel a potential candidate for controlled drug delivery system.

Supramolecular self-assembly induced graphene oxide based hydrogels and organogels.

We demonstrate the construction of three-dimensional graphene oxide based gel networks through the self-assembly of a series of amphiphilic molecules, which possess a polar carbohydrate headgroup attached to a nonpolar pyrene group. The gelation process can occur in both aqueous and organic solutions and be influenced by the gelators' molecular structure. The driving forces for the gelation process were determined as π-π stacking and hydrogen bonding interaction by using fluorescence and infrared spectroscopies. Rheometry was used to investigate the mechanical properties of the hydrogels and the organogels. The hydrogel was investigated to be applied to remove dye from aqueous solution.

Sugar-functionalized water-soluble cyclotriveratrylene derivatives: preparation and interaction with fullerene.

Cyclotriveratrylene (CTV) has attracted much attention because of its good chemical stability, small cavity, stable conformation, and facile modification. In this article, two water-soluble CTV derivatives (CTV-G and CTV-L) functionalized by glucose and lactose residues were synthesized, respectively. Unexpectedly, sugar-bearing CTVs exhibit a distinct photoluminescence, which might be ascribed to the enhanced planar conformation of cyclotriveratrylene ring derived from the spatial effect of bulky branch groups. The interaction between the water-soluble CTV derivatives and C(60) was investigated in organic solvent and aqueous solution, which was further characterized by fluorescence spectra, ultraviolet-visible spectra, and Raman spectra. CTV-G can associate with C(60) to form supramolecular complex with 1:1 molar ratio (K(a) = 1.38 × 10(5) M(-1), 298 K). As for CTV-L, a similar complex with a lower association constant (K(a) = 5.09 × 10(4) M(-1), 298 K) can also be formed.

Tetraphenylethylene-based glycoconjugate as a fluorescence "turn-on" sensor for cholera toxin.

Tetraphenylethylene (TPE)-based glycoconjugates were easily synthesized by copper(I)-catalyzed "click reactions" between propargyl-attached TPE and azido-functionalized sugars. The TPE compound bearing lactosyl moieties (Lac-TPE) was found to be a fluorescence "turn-on" sensor for cholera toxin by virtue of aggregation-induced emission characteristics of the TPE motif owing to the specific interaction of lactose with the cholera toxin B subunit, whilst a cellobiose-functionalized TPE derivative did not show any response to the toxin. Therefore, Lac-TPE shows promising applications in the detection of cholera toxin, as well as in the investigation of carbohydrate-protein interaction.

Glucosamine hydrochloride functionalized water-soluble conjugated polyfluorene: synthesis, characterization, and interactions with DNA.

Novel glucosamine hydrochloride functionalized water-soluble conjugated polyfluorene was easily synthesized through Cu(I)-catalyzed azide/alkyne "click" ligation and Suzuki coupling polymerization. The water-solubility and biocompatibility of the polymer were improved after grafting glucosamine hydrochloride to the side chains of the conjugated polymer. As a fluorescent model system of chitosan, its interaction with single-stranded DNA was studied by spectrofluorometric titration.