Occurrence and seasonal dynamics of Pseudodactylogyrus anguillae (Yin & Sproston) (Monogenea) in eel, Anguilla anguilla (L.), in England

Established populations of Pseudodacrylogyrus anguillae are reported from eels in England for the first time. Prevalence and abundance peak in late summer in all three localities and the parasite overwinters at low levels on eels.     

Determination of baseline susceptibility to Cry1Ab protein for Asian corn borer (Lep., Crambidae)

Abstract: Although transgenic Bacillus thuringiensis (Bt) corn can provide a new tool for control of the Asian corn borer (ACB), Ostrinia furnacalis (Guenée), concern has been raised regarding the possibility of the target insect evolving resistance to the Bt protein under intensive selection pressure from Bt corn. Therefore, it is necessary to establish baseline data to enable detection of changes in susceptibility in field populations after prolonged exposure to Bt corn. Susceptibility to purified Cry1Ab protein from Bt was determined for 10 populations of ACB from the major corn‐growing regions of China, ranging geographically from Heilongjiang Province in the northeast to Shaanxi Province in the east‐central part. Neonate ACB were exposed to semi‐artificial diet incorporated with increasing Cry1Ab protein concentrations, and mortality and growth inhibition were evaluated after 7 days. The range of LC₅₀ (50% lethal concentration) among the populations was 0.10 to 0.81 μg/g (Cry1Ab protein/diet). Differences (P < 0.05) in susceptibility among the populations were significant. LC₅₀s generated from the Huanghuaihai Summer Corn Region were higher than those from the Spring Corn Regions. Bt was one of the significant natural biomortality factors of overwintering generation ACB. There was a significant correlation between percentage of the larvae infected with Bt and their LC₅₀ values to Cry1Ab protein in geographic distinct populations (r = 0.7350*, d.f. = 8, _r0.05 = 0.632). Based on the background of Bt formulations used for corn insect pests control in these areas, these differences were not caused by prior exposure to Bt insecticides. Instead, the small differences likely reflect natural Bt selection pressure. Because the variation in susceptibility to Cry1Ab was small (<10‐fold), the ACB apparently is susceptible to Cry1Ab across its range within China.     

Expression of Discoidin Domain Receptor 2 (DDR2) Extracellular Domain in Pichia Pastoris and Functional Analysis in Synovial Fibroblasts and NIT3T3 Cells

Discoidin domain receptor 2 (DDR2) is a kind of protein tyrosine kinases associated with cell proliferation and tumor metastasis, and collagen, identified as a ligand for DDR2, up-regulates matrix metallloproteinase 1 (MMP-1) and MMP-2 expression in cellular matrix. To investigate the roles of DDR2 in destruction of cartilage in rheumatoid arthritis (RA) and tumor metastasis, we tried to express extracellular domain of DDR2 fused with a His tag to increase protein solubility and facilitate purification (without signal peptide and transmembrane domain, designated DR) in Pichia pastoris, purify the expressed protein, and characterize its function, for purpose of future application as a specific DDR2 antagonist. Two clones of relative high expression of His-DR were obtained, After purification by a Ni-NTA (nitric-tri-acetic acid) chromatographic column, soluble fused His-DR over 90% purity were obtained. Competitive binding inhibition assay demonstrated that expressed His-DR could block the binding of DDR2 and natural DDR2 receptors on NIT3T3 and synovial cell surfaces. Results of RT-PCR, Western blotting, and gelatinase zymography showed that His-DR was capable of inhibiting MMP-1 and MMP-2 secretion from NIT3T3 cells and RA synoviocytes stimulated by collagen II. For MMP-1, the inhibitory effect was displayed at the levels of mRNA and protein, whereas for MMP-2 it was demonstrated at the level of protein physiological activity. All these findings suggested that the fused expressed His-DR inhibited the activity of natural DDR2, and relevant MMP-1 and MMP-2 expression in synoviocytes and NIH3T3 cells provoked by collagen II. Wei Zhang and Tianbing Ding equally contributed to this work.     

Targeting and non-targeting effects of nanomaterials on DNA: challenges and perspectives

Due to their large-scale manufacture and widespread application, there have been a number of studies related to toxicological assessment of nanomaterials (NMs) over the past decade. Although there has been extensive research on the cytotoxicity of NMs, concerns have been raised about their possible genotoxicity. The genome is constantly exposed to genotoxic insults that can lead to DNA damage, which in turn can have consequences for health, such as the induction of carcinogenesis. This comprehensive review focuses on the direct and indirect interactions of NMs with DNA. Factors influencing the genotoxicity of NMs, such as their physicochemical characteristics, are also discussed. The mechanisms involved in the direct and indirect interactions of NMs with DNA are also reviewed. Many studies have shown that ENMs have genotoxic effects, such as chromosomal fragmentation, DNA strand breaks, point mutations, oxidative DNA adducts, apoptosis, hypoxic responses, mitochondrial dysfunction, and epigenetic modifications. As the data reported to date are inconsistent, it is difficult to draw definitive conclusions regarding the features of NMs that promote genotoxicity. Therefore, challenges and future research perspectives are discussed. This review provides insights into the genotoxic effects of NMs and their consequences for human health.

     

Temperature Sensor Based on Hollow Fiber Filled with Graphene-Ag Composite Nanowire and Liquid

A temperature sensor based on hollow fiber (HF) filled with graphene-Ag composite nanowire and liquid is presented. The coupling properties and sensing performance are numerically analyzed by finite element method using wavelength and amplitude interrogations. Results show that the sensor exhibiting strong birefringence with x-polarized peak provides much higher sensitivities and better signal-to-noise ratio (SNR) than y-polarized, which is more suitable for temperature detection. The graphene-Ag composite nanowire can not only solve the oxidation problem but also avoid the metal coating. Moreover, it provides better performance than other similar works like Au-Ag nanowire-filled, Au nanowire-filled, and Ag nanowire-filled sensors. Contrary to the blue shift of traditional SPR temperature sensors, the resonance peak shifts to the longer wavelength in our device when temperature increases and the high sensitivity 9.44 nm/ °C is obtained. The influences of nanowire diameter, grapheme-layer thickness on the designed sensor, are also investigated. This work can provide a reference for developing a high sensitivity, real-time, remote sensing, and distributed temperature SPR sensor.     

Cloning,expression and biochemical characterization of a GH1 β-glucosidase from Cellulosimicrobium cellulans

β-Glucosidase plays an important role in the degradation of cellulose. In this study, a novel β-glucosidase ccbgl1b gene for a glycosyl hydrolase (GH) family 1 enzyme was cloned from the genome of Cellulosimicrobium cellulans and expressed in Escherichia coli BL21 cells. The sequence contained an open reading frame of 1494?bp, encoded a polypeptide of 497?amino acid residues. The recombinant protein CcBgl1B was purified by Ni sepharose fastflow affinity chromatography and had a molecular weight of 57?kDa, as judged by SDS-PAGE. The optimum β-glucosidase activity was observed at 55?°C and pH 6.0. Recombinant CcBgl1B was found to be most active against aryl-glycosides p-nitrophenyl-β-D-glucopyranoside (pNPβGlc), followed by p-nitrophenyl-β-D-galactopyranoside (pNPβGal). Using disaccharides as substrates, the enzyme efficiently cleaved β-linked glucosyl-disaccharides, including sophorose (β-1,2-), laminaribiose (β-1,3-) and cellobiose (β-1,4-). In addition, a range of cello-oligosaccharides including cellotriose, cellotetraose and cellopentaose were hydrolysed by CcBgl1B to produce glucose. The interaction mode between the enzyme and the substrates driving the reaction was modelled using a molecular docking approach. Understanding how the GH1 enzyme CcBgl1B from C. cellulans works, particularly its activity against cello-oligosaccharides, would be potentially useful for biotechnological applications of cellulose degradation.     

Molecular mechanism of the enhanced virulence of 2009 pandemic Influenza A (H1N1) virus from D222G mutation in the hemagglutinin: a molecular modeling study

D222G mutation of the hemagglutinin (HA) is of special interest because of its close association with the enhanced virulence of 2009 pandemic influenza A (H1N1) virus through the increased binding affinity to α2,3-linked sialylated glycan receptors. However, there is still a lack of detailed understanding about the molecular mechanism of this enhanced virulence. Here, molecular dynamics simulation and binding free energy calculation were performed to explore the altered glycan receptor binding mechanism of HA upon the D222G mutation by studying the interaction of one α2,3-linked sialylglycan (sequence: SIA-GAL-NAG) with the wild type and D222G mutated HA. The binding free energy calculation based on the molecular mechanics generalized Born surface area (MM-GBSA) method indicates that the D222G mutated HA has a much stronger binding affinity with the studied α2,3-linked glycan than the wild type. This is consistent with the experimental result. The increased binding free energy of D222G mutant mainly comes from the increased energy contribution of Gln223. The structural analysis proves that the altered electrostatic potential of receptor binding domain (RBD) and the increased flexibility of 220-loop are the essential reasons leading to the increased affinity of HA to α2,3-linked sialic acid glycans. The obtained results of this study have allowed a deeper understanding of the receptor recognition mechanism and the pathogenicity of influenza virus, which will be valuable to the structure-based inhibitors design targeting influenza virus entry process.     

Application of electrospray ionization mass spectrometry in rapid typing of fengycin homologues produced by Bacillus subtilis

AIMS: To rapidly type the fengycin homologues produced by Bacillus subtilis strains with electrospray ionization/collision-induced dissociation (ESI/CID) mass spectrometry. METHODS AND RESULTS: Fengycin homologues produced by Bacillus subtilis JA were analysed. When each homologue was subjected to ESI/CID analysis, ions representing characteristic fragmentations were detected. These ions can help to identify the homologues; even homologues of the same nominal mass can be discriminated by their ESI/CID spectra. Based on the CID results, fengycin homologues can be correctly assigned. CONCLUSIONS AND SIGNIFICANCE OF THIS STUDY: ESI/CID leads to rapid detection and structural characterization of fengycin homologues or lipopeptides with similar properties. It will be very useful in studying the regulatory expression of these peptides.