Gene knockdown by intro-thoracic injection of double-stranded RNA in the brown planthopper,Nilaparvata lugens

RNA interference (RNAi) is a powerful strategy for gene function study in insects. Here, we described the development of a RNAi technique by microinjection of double-stranded RNA (dsRNA) in the brown planthopper Nilaparvata lugens. Based on the mortality and RNAi efficiency criteria, the conjunctive between prothorax and mesothorax was selected as the injection site and 50 nl as injection volume. Three genes with different expression patterns were selected to evaluate the RNAi efficiency. A comparable 40% decrease of gene expression was observed at the 4th day after injection for the ubiquitously expressed calreticulin and the gut specific cathepsin-B genes, but only 25% decrease at the 5th day for the central nervous system specific Nlβ2 gene. Double injection could increase the RNAi efficiency, such as from 25% to 53% for Nlβ2 gene. The gene knockdown technique developed in this study will be an essential post-genomic tool for further investigations in N. lugens.     

Green Fluorescent Protein Labeling Escherichia coli TG1 Confirms Intestinal Bacterial Translocation in a Rat Model of Chemotherapy

It has been reported that treatment with methotrexate (MTX) induces intestinal bacterial translocation; however, the definitive evidence of intestinal bacterial translocation induced by MTX has been lacking. The aim of this study was to confirm the intestinal bacterial translocation caused by MTX and to evaluate the preventive effect of granulocyte colony-stimulating factor (G-CSF) on intestinal bacterial translocation caused by MTX. Sprague-Dawley rats were treated with MTX (3.5 mg/kg) for 3 days to induce intestinal bacterial translocation; with gavaged Escherichia coli TG1 labeled with green fluorescent protein (GFP) for 2 days to track intestinal bacterial translocation; and with G-CSF (10 μg/kg) for 4 days to prevent intestinal bacterial translocation. Representative tissue specimens from the mesenteric lymph nodes, spleen, liver, and kidney were aseptically harvested for bacteria culture in ampicillin-supplemented medium. The bacteria labeled with GFP were detected in tissue specimens harvested from the rats treated with MTX but not detected in the rats that were not treated with MTX. G-CSF significantly ameliorated the situation of intestinal bacterial translocation.     

BAFF induces spleen CD4(+) T cell proliferation by down-regulating phosphorylation of FOXO3A and activates cyclin D2 and D3 expression

The TNF ligand family member "B cell-activating factor belonging to the TNF family" (BAFF, also called BLyS, TALL-1, zTNF-4, and THANK) is an important survival factor for B and T cells. In this study, we show that BAFF is able to induce CD4(+) spleen T cell proliferation when co-stimulated with anti-CD3. Expression of phosphorylated FOXO3A was notably down-regulated and cyclins D2 and D3 were up-regulated and higher in the CD4(+) T cells when treated with BAFF and anti-CD3, as assessed by Western blotting. Furthermore, after FOXO3A was knocked down, expression of cyclin D1 was unchanged, compared with control group levels, but the expression of cyclins D2 and D3 increased, compared with the control group. In conclusion, our results suggest that BAFF induced CD4(+) spleen T cell proliferation by down-regulating the phosphorylation of FOXO3A and then activating cyclin D2 and D3 expression, leading to CD4(+) T cell proliferation.     

Discovery of multiple IGS haplotypes within genotypes of Puccinia striiformis

In a search for specific molecular markers for population analysis of Puccinia striiformis f. sp. tritici, the ribosomal DNA (rDNA) intergenic spacer (IGS) 1 region (rDNA-IGS1, between the 28S and the 5S rDNA genes) was amplified, cloned, and sequenced. It was found to exhibit multiple bands and length polymorphism. Surprisingly, single isolates were found to possess between three to five different IGS1 haplotypes. Bands were cloned and sequenced, and two highly variable regions (α and β) were found between conserved regions, with repeat units interspersed in both types of regions. There were 14 different repeat units, and these were sometimes grouped further into four combinations of repeat units, with a few individual nucleotides (A or C) inserted between the repeats. Among three geographically dispersed isolates, the variable region α was divided into eight types, and the variable region β was divided into two types based on repeat units. Most of the 14 repeat units were shared by the variable and the conserved regions. Among the three isolates, there were a total of 12 IGS1 haplotypes, but some of these were shared between isolates such that there were only eight unique haplotypes. The occurrence of multiple haplotypes within single isolates may be useful for analyzing the population structure, tracking the origin of annual epidemics and providing insights into evolutionary biology of this pathogen.     

A theoretical study on the hydrolysis mechanism of carbon disulfide

The hydrolysis mechanism of CS(2) was studied using density functional theory. By analyzing the structures of the reactant, transition states, intermediates, and products, it can be concluded that the hydrolysis of CS(2) occurs via two mechanisms, one of which is a two-step mechanism (CS(2) first reacts with an H(2)O, leading to the formation of the intermediate COS, then COS reacts with another H(2)O, resulting in the formation of H(2)S and CO(2)). The other is a one-step mechanism, where CS(2) reacts with two H(2)O molecules continuously, leading to the formation of H(2)S and CO(2). By analyzing the thermodynamics and the change in the kinetic function, it can be concluded that the rate-determining step involves H and OH in H(2)O attacking S and C in CS(2), respectively, causing the C=S double bond to change into a single bond. The two mechanisms are competitive. When performing the hydrolysis of CS(2) with a catalyst, the optimal temperature is below 252°C.     

Optical fan for single‐cell screening

The single‐cell screening has attracted great attentions in advanced biomedicine and tissue biology, especially for the early disease diagnosis and treatment monitoring. In this work, by using a specific‐designed fiber probe with a flat facet, we propose an “optical fan” strategy to screen K562 cells at the single‐cell level from a populations of RBCs. After the 980‐nm laser beam injected into the fiber probe, the RBCs were blown away but holding target K562 cells in place. Further, multiple leukemic cells can be screened from hundreds of red blood cells, providing an efficient approach for the cell screening. The experimental results were interpreted by the numerical simulation, and the stiffness of optical fan was also discussed.     

Study of Displacement Efficiency and Flow Behavior of Foamed Gel in Non-Homogeneous Porous Media

Field trials have demonstrated that foamed gel is a very cost-effective technology for profile modification and water shut-off. However, the mechanisms of profile modification and flow behavior of foamed gel in non-homogeneous porous media are not yet well understood. In order to investigate these mechanisms and the interactions between foamed gel and oil in porous media, coreflooding and pore-scale visualization waterflooding experiments were performed in the laboratory. The results of the coreflooding experiment in non-homogeneous porous media showed that the displacement efficiency improved by approximately 30% after injecting a 0.3 pore volume of foamed gel, and was proportional to the pore volumes of the injected foamed gel. Additionally, the mid-high permeability zone can be selectively plugged by foamed gel, and then oil located in the low permeability zone will be displaced. The visualization images demonstrated that the amoeba effect and Jamin effect are the main mechanisms for enhancing oil recovery by foamed gel. Compared with conventional gel, a unique benefit of foamed gel is that it can pass through micropores by transforming into arbitrary shapes without rupturing, this phenomenon has been named the amoeba effect. Additionally, the stability of foam in the presence of crude oil also was investigated. Image and statistical analysis showed that these foams boast excellent oil resistance and elasticity, which allows them to work deep within formations.     

The Impact of Device Polarity on the Performance of Polymer–Fullerene Solar Cells

Diketopyrrolopyrrole (DPP)‐conjugated polymers are a versatile class of semiconductors for application in organic solar cells because of their tunable optoelectronic properties. A record power conversion efficiency (PCE) of 9.4% was recently achieved for DPP polymers, but further improvements are required to reach true efficiency limits. Using five DPP polymers with different chemical structures and molecular weights, the device performance of polymer:fullerene solar cells is systematically optimized by considering device polarity, morphology, and light absorption. The polymer solubility is found to have a significant effect on the optimal device polarity. Soluble polymers show a 10–25% increase in PCE in inverted device configurations, while the device performance is independent of device polarity for less soluble DPP derivatives. The difference seems related to the polymer to fullerene weight ratio at the ZnO interface in inverted devices, which is higher for more soluble DPP polymers. Optimization of the nature of the cosolvent to narrow the fibril width of polymers in the blends toward the exciton diffusion length enhances charge generation. Additionally, the use of a retroreflective foil increases absorption of light. Combined, the effects afford a PCE of 9.6%, among the highest for DPP‐based polymer solar cells.     

油桐尺蠖单粒包埋核型多角体病毒（BusuNPV）BamHI—H片段的序列分析

对油桐尺蠖单粒包埋核型多用体病毒（Buzurasuppressariasingle－nucleocapsidnucleopolyhedrovirus,BusuNPV）基因组中BamHI－H片段的序列进行分析,该片段全长2422bp,包括三个开放阅读框：p47基因（AcMNPVORF40的同源区）的5′端,完整的组织蛋白酶基因（cathepsin）（AcMNPVORF127的同源区）和p74基因（AcMNPVORF138的同源区）的3′端。序列比较分析表明,BusuNPV的这三个基因与其它杆状病毒的同源基因具有相同的结构保守区。BusuNPV基因组BamHI－H片段上这三个基因的排列顺序完全不同于AcMNPV相应基因的排列顺序。     

Programming living sensors for environment,health and biomanufacturing

Synthetic biology offers new tools and capabilities of engineering cells with desired functions for example as new biosensing platforms leveraging engineered microbes. In the last two decades, bacterial cells have been programmed to sense and respond to various input cues for versatile purposes including environmental monitoring, disease diagnosis and adaptive biomanufacturing. Despite demonstrated proof-of-concept success in the laboratory, the real-world applications of microbial sensors have been restricted due to certain technical and societal limitations. Yet, most limitations can be addressed by new technological developments in synthetic biology such as circuit design, biocontainment and machine learning. Here, we summarize the latest advances in synthetic biology and discuss how they could accelerate the development, enhance the performance and address the present limitations of microbial sensors to facilitate their use in the field. We view that programmable living sensors are promising sensing platforms to achieve sustainable, affordable and easy-to-use on-site detection in diverse settings.