Ultrabright fluorescent microsphere and its novel application for improving the sensitivity of immunochromatographic assay.

Fluorescent microsphere (FM) is widely used as probe in immunochromatographic assay (ICA). However, the performance of conventional FM is limited because of the aggregation-caused quenching effect. Herein, we compared a kind of conventional FM (DMFFM, loading DMF) with novel aggregation-induced emission FM (AIEFM, loading TCBPE).

Strategy for Accurate Detection of Escherichia Coli O157:H7 in Ground Pork Using a Lateral Flow Immunoassay.

O157:H7 is known to cause serious diseases including hemorrhagic colitis and hemolytic uremic syndrome. A gold nanoparticle lateral flow immunoassay (Au-LFIA) was used to detect O157:H7 in ground pork samples. False-positive results were detected using Au-LFIA; a strain was isolated from the ground pork samples and identified by using CHROmagar plates, API 20E, and 16S RNA sequencing.

DNA-based hybridization chain reaction and biotin-streptavidin signal amplification for sensitive detection of Escherichia coli O157:H7 through ELISA.

This study reported on a novel sandwich enzyme linked immunosorbent assay (ELISA) for the sensitive determination of Escherichia coli O157:H7 (E. coli O157:H7) by using DNA-based hybridization chain reaction (HCR) and biotin-streptavidin signal amplification. The anti-E.

Increased L-arginine Production by Site-directed Mutagenesis of N-acetyl-L-glutamate Kinase and proB Gene Deletion in Corynebacterium crenatum.

Objective: In Corynebacterium crenatum, the adjacent D311 and D312 of N-acetyl-L-glutamate kinase (NAGK), as a key rate-limiting enzyme of L-arginine biosynthesis under substrate regulatory control by arginine, were initially replaced with two arginine residues to investigate the L-arginine feedback inhibition for NAGK.

Methods: NAGK enzyme expression was evaluated using a plasmid-based method. Homologous recombination was employed to eliminate the proB.

Development of a nanobody-alkaline phosphatase fusion protein and its application in a highly sensitive direct competitive fluorescence enzyme immunoassay for detection of ochratoxin A in cereal.

A rapid and sensitive direct competitive fluorescence enzyme immunoassay (dc-FEIA) for ochratoxin A (OTA) based on a nanobody (Nb)-alkaline phosphatase (AP) fusion protein was developed. The VHH (variable domain of heavy chain antibody) gene of Nb28 was subcloned into the expression vector pecan45 containing the AP double-mutant gene. The Nb28-AP construct was transformed into Escherichia coli BL21(DE3)plysS, and soluble expression in bacteria was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot.

VHH phage-based competitive real-time immuno-polymerase chain reaction for ultrasensitive detection of ochratoxin A in cereal.

Phage display-mediated immuno-polymerase chain reaction (PD-IPCR) is an ultrasensitive detection technology that combines the advantages of immuno-PCR and phage display. The phage particle, which displayed antibody fragments including single-chain fragment variable (scFv), variable domain of heavy-chain antibodies (VHH), and antigen-binding fragment (Fab) on the surface can be directly used in IPCR, supplying both the detection antibody and deoxyribonucleic acid (DNA) template. In this work, we used ochratoxin A (OTA) as a model system to study the capacity of PD-IPCR in the detection of toxic small molecular weight compounds, especially mycotoxins.

Expression and characterization of ArgR, an arginine regulatory protein in Corynebacterium crenatum.

Objective: Corynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production.

Lateral flow immunoassay for quantitative detection of ractopamine in swine urine.

A strip reader based lateral flow immunoassay (LFIA) was established for the rapid and quantitative detection of ractopamine (RAC) in swine urine. The ratio of the optical densities (ODs) of the test line (AT) to that of the control line (AC) was used to effectively minimize interference among strips and sample variations. The linear range for the quantitative detection of RAC was 0.

Advantages of fluorescent microspheres compared with colloidal gold as a label in immunochromatographic lateral flow assays.

Label selection is of vital importance for immunochromatographic assays. In this study, the fluorescent microsphere test strip and colloidal gold immunochromatographic test strip (FM-ICTS and CG-ICTS) were developed for the detection of Escherichia coli O157:H7 on the basis of the sandwich format. Two types of labels, namely, colloidal gold particles (CG) and carboxyl-modified fluorescent microspheres (FMs), were compared while coupling with anti-E.

Differentially-expressed genes in Candida albicans exposed to ε-poly-L-lysine.

Candida albicans is an opportunistic human pathogen whose disinfection is a challenge. ε-Poly-L-lysine (ε-PL), an antagonistic agent, can disrupt cell membranes and inhibit the growth of C. albicans.

[Genetic polymorphism of eleven canine STR loci].

Objective: To investigate the polymorphism of 11 canine STR loci.

Methods: A fluorescent multiplex system with 11 STR loci (PEZ1, PEZ2, PEZ3, PEZ5, PEZ6, PEZ8, PEZ12, FH2010, FH2054, FH2132 and FH2611) was constructed independently and performed to amplify 105 samples from dogs. The character of these loci was analyzed with the PCR data.

Cloning and sequence analysis of the full-length cDNA of a novel yp05 gene associated with citrinin production in Monascus aurantiacus.

Objective: To obtain the full-length cDNA of a novel gene (named yp05) associated with citrinin production-related genes in Monascus aurantiacus.

Methods: Total RNA was extracted from mycelium, 3' and 5' cDNA end of yp05 gene was amplified using smart trace cDNA amplification kit, and the full-length cDNA of a novel gene (named yp05) was obtained from the electronic assembly of 3'-RACE and 5'-RACE products.

Results: This yp05 gene was 787 bp including a 597 bp open reading frame (ORF) and encoded a deduced protein with 199 amino acid residues, and the amino acid sequence of this protein was found similar with the sequences of many fungal manganese-superoxide dismutases in the GenBank with the aid of BLASTp.

[Research progress in analysis methods of Aflatoxins].

Aflatoxins, a group of toxins structurally related to secondary metabolites are produced by some fungal strains. Many countries developed legislations to regulate and control aflatoxins in food and feed because they are extremely toxic, potent carcinogenic and ubiquitous in the environment. Different analytical methods are currently used: TLC, HPLC, ELISA, RIA, CE, and IC, etc.

Serial analysis of gene expression in Monascus aurantiacus producing citrinin.

Objective: To construct a tag expression library of Monascus aurantiacus that could produce citrinin maximally on the thirteenth (0.966 mg/mL) day in the submerged culture.

Methods: Total RNA was extracted from the mycelium, cDNA was synthesized using the SuperScript choice system, and then, a SAGE library was successfully constructed according to the MicroSAGE method.

[Technological advances of serial analysis of gene expression].

Serial analysis of gene expression (SAGE) is an effective method of determining gene expression profiles of tissues and organs under different conditions. In this paper, the detail protocol of SAGE was introduced and some modified procedure of SAGE was reviewed.