Restoring colistin sensitivity in colistin-resistant and : combinatorial use of berberine and EDTA with colistin.

Unlabelled: The appearance and prevalence of multidrug-resistance (MDR) Gram-negative bacteria (GNB) have limited our antibiotic capacity to control bacterial infections. The clinical efficacy of colistin (COL), considered as the "last resort" for treating GNB infections, has been severely hindered by its increased use as well as the emergence and prevalence of mobile colistin resistance (MCR)-mediated acquired drug resistance. Identifying promising compounds to restore antibiotic activity is becoming an effective strategy to alleviate the crisis of increasing MDR.

Repair of critical-sized rat cranial defects with RADA16-W9 self-assembled peptide hydrogel.

Bone defects are common in orthopaedics and there is an urgent need to explore effective bone repair materials with osteoinductive activity. Peptide self-assembled nanomaterials have a fibrous structure like that of the extracellular matrix and are ideal bionic scaffold materials. In this study, a short peptide WP9QY (W9) with strong osteoinductive effect was tagged to a self-assembled peptide RADA16 molecule through solid phase synthesis to design a RADA16-W9 peptide gel scaffold.

Synergistic antibacterial activity of baicalin and EDTA in combination with colistin against colistin-resistant Salmonella.

The emergence and rapid spread of multidrug resistant (MDR) Gram-negative bacteria have posed a serious threat to global health and security. Because of the time-consuming, high cost and high risk of developing new antibiotics, a significant method is to use antibiotic adjuvants to revitalize the existing antibiotics. The purpose of the study is to research the traditional Chinese medicine baicalin with the function of inhibiting the efflux pump and EDTA whether their single or combination can increase the activity of colistin against colistin-resistant Salmonella in vitro and in vivo, and to explore its molecular mechanisms.

Enhancing oxidation resistance of Cu(I) by tailoring microenvironment in zeolites for efficient adsorptive desulfurization.

The zeolite Cu(I)Y is promising for adsorptive removal of thiophenic sulfur compounds from transportation fuels. However, its application is seriously hindered by the instability of Cu(I), which is easily oxidized to Cu(II) even under atmospheric environment due to the coexistence of moisture and oxygen. Here, we report the adjustment of zeolite microenvironment from hydrophilic to superhydrophobic status by coating polydimethylsiloxane (yielding Cu(I)Y@P), which isolates moisture entering the pores and subsequently stabilizes Cu(I) despite the presence of oxygen.

β3-Adrenergic Activation Improves Maternal and Offspring Perinatal Outcomes in Diet-Induced Prepregnancy Obesity in Mice.

Objective: Prepregnancy obesity is an epidemic disorder that seriously threatens both maternal and offspring health. This study investigated the effects of β3-adrenergic receptor (β3-AR) activation on the perinatal outcomes in a diet-induced prepregnancy obese (PPO) murine model.

Methods: Four-week-old female C57BL/6 mice were fed high-fat diet or chow diet for 16 weeks to yield PPO mice and chow-fed (CF) lean mice, respectively.

Conserved biosynthetic pathways for phosalacine, bialaphos and newly discovered phosphonic acid natural products.

Natural products containing phosphonic or phosphinic acid functionalities often display potent biological activities with applications in medicine and agriculture. The herbicide phosphinothricin-tripeptide (PTT) was the first phosphinate natural product discovered, yet despite numerous studies, questions remain surrounding key transformations required for its biosynthesis. In particular, the enzymology required to convert phosphonoformate to carboxyphosphonoenolpyruvate and the mechanisms underlying phosphorus methylation remain poorly understood.

Discovery of phosphonic acid natural products by mining the genomes of 10,000 actinomycetes.

Although natural products have been a particularly rich source of human medicines, activity-based screening results in a very high rate of rediscovery of known molecules. Based on the large number of natural product biosynthetic genes in microbial genomes, many have proposed "genome mining" as an alternative approach for discovery efforts; however, this idea has yet to be performed experimentally on a large scale. Here, we demonstrate the feasibility of large-scale, high-throughput genome mining by screening a collection of over 10,000 actinomycetes for the genetic potential to make phosphonic acids, a class of natural products with diverse and useful bioactivities.

Diversity and abundance of phosphonate biosynthetic genes in nature.

Phosphonates, molecules containing direct carbon-phosphorus bonds, compose a structurally diverse class of natural products with interesting and useful biological properties. Although their synthesis in protozoa was discovered more than 50 y ago, the extent and diversity of phosphonate production in nature remains poorly characterized. The rearrangement of phosphoenolpyruvate (PEP) to phosphonopyruvate, catalyzed by the enzyme PEP mutase (PepM), is shared by the vast majority of known phosphonate biosynthetic pathways.

Electrical properties and behaviors of cuprous oxide cubes under high pressure.

An accurate in situ electrical resistivity measurement of cuprous oxide cubes has been conducted in a diamond anvil cell at room temperature with pressures up to 25 GPa. The abnormal electrical resistivity variation found at 0.7-2.

Genetic and biochemical characterization of a pathway for the degradation of 2-aminoethylphosphonate in Sinorhizobium meliloti 1021.

A variety of microorganisms have the ability to use phosphonic acids as sole sources of phosphorus. Here, a novel pathway for degradation of 2-aminoethylphosphonate in the bacterium Sinorhizobium meliloti 1021 is proposed based on the analysis of the genome sequence. Gene deletion experiments confirmed the involvement of the locus containing phnW, phnA, and phnY genes in the conversion of 2-aminoethylphosphonate to inorganic phosphate.

[Expression of HER-2/neu oncogene in hepatocellular carcinoma and the clinical implications].

Objective: To investigate the expression of human epidermal growth factor receptor 2 (HER-2/neu) in hepatocellular carcinoma (HCC) patients and its clinical significance.

Methods: The expressions of HER-2/neu were detected by SP immunohistochemistry method in 30 patients with HCC, 10 with portal cirrhosis of the liver and 10 with normal liver.

Results: The positivity rate of HER-2/neu was markedly higher in HCC patients than in those with portal cirrhosis and normal liver (Chi(2)=6.

Biosynthesis of rhizocticins, antifungal phosphonate oligopeptides produced by Bacillus subtilis ATCC6633.

Rhizocticins are phosphonate oligopeptide antibiotics containing the C-terminal nonproteinogenic amino acid (Z)-l-2-amino-5-phosphono-3-pentenoic acid (APPA). Here we report the identification and characterization of the rhizocticin biosynthetic gene cluster (rhi) in Bacillus subtilis ATCC6633. Rhizocticin B was heterologously produced in the nonproducer strain Bacillus subtilis 168.

New methods for tightly regulated gene expression and highly efficient chromosomal integration of cloned genes for Methanosarcina species.

A highly efficient method for chromosomal integration of cloned DNA into Methanosarcina spp. was developed utilizing the site-specific recombination system from the Streptomyces phage phiC31. Host strains expressing the phiC31 integrase gene and carrying an appropriate recombination site can be transformed with non-replicating plasmids carrying the complementary recombination site at efficiencies similar to those obtained with self-replicating vectors.

Class I and class II lysyl-tRNA synthetase mutants and the genetic encoding of pyrrolysine in Methanosarcina spp.

Methanosarcina spp. begin methanogenesis from methylamines with methyltransferases made via the translation of UAG as pyrrolysine. In vitro evidence indicates two possible routes to pyrrolysyl-tRNA(Pyl).

Characterization of a Methanosarcina acetivorans mutant unable to translate UAG as pyrrolysine.

The methyltransferases initiating methanogenesis from trimethylamine, dimethylamine and monomethylamine possess a novel residue, pyrrolysine. Pyrrolysine is the 22nd amino acid, because it is encoded by a single amber (UAG) codon in methylamine methyltransferase transcripts. A dedicated tRNA(CUA) for pyrrolysine, tRNA(Pyl), is charged by a pyrrolysyl-tRNA synthetase with pyrrolysine.

Genetic analysis of mch mutants in two Methanosarcina species demonstrates multiple roles for the methanopterin-dependent C-1 oxidation/reduction pathway and differences in H(2) metabolism between closely related species.

A mutation in the mch gene, encoding the enzyme 5,10-methenyl tetrahydromethanopterin (H(4)MPT) cyclohydrolase, was constructed in vitro and recombined onto the chromosome of the methanogenic archaeon Methanosarcina barkeri. The resulting mutant does not grow in media using H(2)/CO(2), methanol, or acetate as carbon and energy sources, but does grow in media with methanol/H(2)/CO(2), demonstrating its ability to utilize H(2) as a source of electrons for reduction of methyl groups. Cell suspension experiments showed that methanogenesis from methanol or from H(2)/CO(2) is blocked in the mutant, explaining the lack of growth on these substrates.

Molecular cloning, sequence analysis, and heterologous expression of the phosphinothricin tripeptide biosynthetic gene cluster from Streptomyces viridochromogenes DSM 40736.

A fosmid library from genomic DNA of Streptomyces viridochromogenes DSM 40736 was constructed and screened for the presence of genes known to be involved in the biosynthesis of phosphinothricin tripeptide (PTT). Eight positives were identified, one of which was able to confer PTT biosynthetic capability upon Streptomyces lividans after integration of the fosmid into the chromosome of this heterologous host. Sequence analysis of the 40,241-bp fosmid insert revealed 29 complete open reading frames (ORFs).

Development of a markerless genetic exchange method for Methanosarcina acetivorans C2A and its use in construction of new genetic tools for methanogenic archaea.

A new genetic technique for constructing mutants of Methanosarcina acetivorans C2A by using hpt as a counterselectable marker was developed. Mutants with lesions in the hpt gene, encoding hypoxanthine phosphoribosyltransferase, were shown to be >35-fold more resistant to the toxic base analog 8-aza-2,6-diaminopurine (8ADP) than was the wild type. Reintroduction of the hpt gene into a Delta hpt host restored 8ADP sensitivity and provided the basis for a two-step strategy involving plasmid integration and excision for recombination of mutant alleles onto the M.

Genetic analysis of the archaeon Methanosarcina barkeri Fusaro reveals a central role for Ech hydrogenase and ferredoxin in methanogenesis and carbon fixation.

Ech hydrogenase (Ech) from the methanogenic archaeon Methanosarcina barkeri catalyzes the reversible reduction of ferredoxin by H(2) and is a member of a distinct group of membrane-bound [NiFe] hydrogenases with sequence similarity to energy-conserving NADH:quinone oxidoreductase (complex I). To elucidate the physiological role(s) of Ech a mutant lacking this enzyme was constructed. The mutant was unable to grow on methanol/H(2)/CO(2), H(2)/CO(2), or acetate as carbon and energy sources but showed wild-type growth rates with methanol as sole substrate.

Directed mutagenesis and plasmid-based complementation in the methanogenic archaeon Methanosarcina acetivorans C2A demonstrated by genetic analysis of proline biosynthesis.

We report here the first use of directed mutagenesis in Methanosarcina acetivorans C2A. The method employs homologous recombination-mediated gene replacement and was used to construct a variety of proline auxotrophs with mutations in the proABC locus. Each mutation was also complemented in trans with autonomously replicating Methanosarcina-Escherichia plasmid shuttle vectors.