Biology subjects

Weng, X.

Publications and source records attributed to Weng, X..

6 recordsLinked to original sources

bioRxiv2018

(-)-Epigallocatechin-3-gallate inhibition of Epstein-Barr virus lytic replication involves latent membrane protein 1-mediated MAPK signaling pathways

AbstractEBV lytic replication has been shown to be important for carcinogenesis. Latent membrane protein 1 (LMP1) plays an important role in the viral latent infection and is abundantly expressed after EBV entry into the lytic cycle. However, the biological significance of LMP1 continuous expression in EBV lytic cycle is still not completely understood. We found that LMP1 promotes EBV reactivation by activating the downstream MAPK signaling in both AGS-EBV and B95.8 cells. In AGS-EBV cells, LMP1 induces EBV the initiation of the EBV lytic cycle in a p53 dependent manner. Activation of c-Jun by LMP1 through JNKs appears to be involved in EBV reactivation in p53 mutant B95.8 cells. We also demonstrated that EGCG, an anti-EBV agent, inhibits LMP1 expression and the activation of the downstream MAPK signaling pathways, followed by downregulation of EBV lytic protein expression level. Together, this study provides the first evidence that LMP1 promotes EBV reactivation via activation of the MAPK signaling pathways. Our findings further demonstrate that the mechanisms underlying EGCG inhibition of the EBV lytic replication involve the suppression of LMP1-mediated MAPK signaling pathways.\n\nSummary statementThis study definitely confirms the role of LMP1 in EBV reactivation and further explores the mechanism by which EGCG inhibits EBV lytic replication.

molecular biology↗

bioRxiv2018

Aptamer-based biosensor for food allergen determination using graphene oxide/gold nanocomposite on a paper-assisted analytical device

The detection of allergens in food are currently conducted by techniques that are time-consuming and complicated which can deter consistent sampling for allergens, which could potentially cause an anaphylactic shock in the consumer by cross-contamination. The need for a technique that is rapid, on-site, cost-effective, disposable, highly sensitive and accurate to identify these molecules urges the development of a point-of-care device. The aim of this work is to develop a microfluidic paper-assisted analytical device (PAD) using hydrophobic channels, set by a wax printer on filter paper, and functionalized gold nanoparticles (AuNP) to help identify the allergens arachin (Ara h 1) for peanuts, {beta}-lactoglobulin ({beta} LG) for milk, and tropomyosin (Pen a 1) for shrimp and other shellfish presence by a colorimetric test. Synthesized AuNP were conjugated with biotinylated aptamers, using the biotin-streptavidin interaction, to make the specific detection of target allergens. Functionalized AuNP are incubated with the sample and are absorbed by graphene oxide (GO), creating GO-AuNP complexes, if the aptamers have not become structured due to conjugation with allergenic proteins. The PAD device is used to filter the resultant mixture which provides superior sensitivity to detect the allergens present down to the nanogram range (allergens were measured from 25 nM - 1000 nM with a LOD of 7.8 nM, 12.4 nM and 6.2 nM for peanut, milk and shrimp allergens respectively), in contrast to the microgram range of commonly used enzymatic immunoassays. The simple color indicator, varying from clear to pink in the presences of allergens allows the readout to be utilized without the need for highly specific equipment or training. Alternatively, the results can be quantified by taking a picture and measuring the color. This presented PAD can provide results in real time and has the potential to become a rapid, low-cost, and accurate portable point-of-care device to avoid cross-reactivity of food-borne allergens.

bioengineering↗

bioRxiv2018

RNA polymerase organizes into distinct spatial clusters independent of ribosomal RNA transcription in E. coli

Recent studies have shown that RNA polymerase (RNAP) is spatially organized into distinct clusters in E. coli and B. subtilis cells. Spatially organized molecular components in prokaryotic systems imply compartmentalization without the use of membranes, which may offer new insights into pertinent functions and regulations. However, the function of RNAP clusters and whether its formation is driven by active ribosomal RNA (rRNA) transcription remain elusive. In this work, we investigated the spatial organization of RNAP in E. coli cells using quantitative superresolution imaging. We observed that RNAP formed large, distinct clusters under a rich medium growth condition and preferentially located in the center of the nucleoid. Two-color superresolution colocalization imaging showed that under the rich medium growth condition, nearly all RNAP clusters were active in synthesizing rRNA, suggesting that rRNA synthesis may be spatially separated from mRNA synthesis that most likely occurs at the nucleoid periphery. Surprisingly, a large fraction of RNAP clusters persisted under conditions in which rRNA synthesis was reduced or abolished, or when only one out of the seven rRNA operons (rrn) remained. Furthermore, when gyrase activity was inhibited, we observed a similar rRNA synthesis level, but multiple dispersed, smaller rRNA and RNAP clusters occupying not only the center but also the periphery of the nucleoid, comparable to an expanded nucleoid. These results suggested that RNAP was organized into active transcription centers for rRNA synthesis under the rich medium growth condition; their presence and spatial organization, however, were independent of rRNA synthesis activity under the conditions used but were instead influenced by the structure and characteristics of the underlying nucleoid. Our work opens the door for further investigations of the function and molecular nature of RNAP clusters and points to a potentially new mechanism of transcription regulation by the spatial organization of individual molecular components.

microbiology↗

bioRxiv2017

Rapid Detection of Norovirus Using Paper-based Microfluidic Device

Noroviruses (NoV) are the leading cause of outbreak of acute gastroenteritis worldwide. A substantial effort has been made in the development of analytical devices for rapid and sensitive food safety monitoring via the detection of foodborne bacteria, viruses and parasites. Conventional analytical approaches for noroviruses suffer from some critical weaknesses: labor-intensive, time-consuming, and relatively low sensitivity. In this study, we developed a rapid and highly sensitive biosensor towards point-of-care device for noroviruses based on 6-carboxyfluorescein (6-FAM) labeled aptamer and nanomaterials, multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO). In an assay, the fluorescence of 6-FAM labeled aptamer was quenched by MWCNTs or GO via fluorescence resonance energy transfer (FRET). In the presence of norovirus, the fluorescence would be recovered due to the release of the 6-FAM labeled aptamer from MWCNTs or GO. An easy-to-make paper-based microfluidic platform made by nitrocellulose membrane was used to conduct the assay. The quantitative detection of norovirus virus-like particles (NoV VLPs) was successfully performed. A linear range of 0-12.9 g/mL with a detection limit of 40 pM and 30 pM was achieved for the MWCNTs and GO based paper sensors, respectively. The results suggested the developed paper-based microfluidic device is simple, cost-effective and holds the potential of rapid in situ visual determination for noroviruses with remarkable sensitivity and specificity, which provides a new way for early identification of NoV and thereby an early intervention for preventing the spread of an outbreak.

bioengineering↗

bioRxiv2017

Paper based microfluidic aptasensor for food safety

Food analysis is requiring rapid, accurate, sensitive and cost-effective methods to monitor and guarantee the safety and quality to fulfill the strict food legislation and consumer demands. In our study, a nano-materials enhanced multipurpose paper based microfluidic aptasensor was demonstrated as a sensing tool for accurate detection of food allergens and food toxins. Graphene oxide (GO) and specific aptamer-functionalized quantum dots (QDs) were employed as probes, the fluorescence quenching and recovering of the QDs caused by the interaction among GO, aptamer-functionalized QDs and the target protein were investigated to quantitatively analyze the target concentration. The homogenous assay was performed on the paper based microfluidic chip, which significantly decreased the sample and reagent consumptions and reduced the assay time. Egg white lysozyme, {beta}-conglutin lupine and food toxins, okadaic acid and brevetoxin standard solutions and spiked food samples were successfully assayed by the presented aptasensor. Dual-target assay was completed within 5 min, and superior sensitivities were achieved when testing the samples with commercial ELISA kits side by side.

bioengineering↗

bioRxiv2017

Chitozyme: First Peroxidase-like Activity of Chitosan for Multiplexed Visual Detection of H2O2, Glucose and Lactate on Paper-based Device

Visual read-out diagnostics tools are promising candidates for field applicable medical devices. Current colorimetric biosensors require introduction of natural enzymes or nanozymes, which has some serious drawbacks for practical applications. Chitosan, a natural polymer, provides safe and efficient compound in medical and pharmaceutical technology. Herein, we report on a simple, cost-efficient, field-portable, environmental friendly and ultra-sensitive multiplex detection platform based on peroxidase-like activity of chitosan in the presence of 3,3,5,5-Tetramethylbenzidine (TMBZ) and H2O2. This straight forward signal amplification strategy was successfully applied to detect H2O2, glucose and lactate with the limit of detection (LOD) of 2.64 pM, 0.104 M and 2.8 nM respectively, represents the lowest LOD of H2O2, glucose and lactate with visual read-out. The chitosan-based assay performance was also retained in complex biological media for glucose and lactate detection. Furthermore, the proposed assay was successfully demonstrated as a paper-based colorimetric biosensor. Most importantly, the simplicity, biocompatibility and sensitivity of the proposed assay will open new doors for instrument free naked eye visual detection of H2O2, glucose and lactate detection.

bioengineering↗