The preparation and characterization of a matrix reference material for aflatoxin M1 in milk powder is described. Milk powder samples containing aflatoxin M1 were found in the screened natural milk samples. The preparation of matrix milk powder samples was developed through steps by vacuum concentration, spray-drying, cooling, mixing, weighing and packaging, and irradiation. This paper has developed a method for the determination of aflatoxin M1 in milk powder by isotope dilution liquid chromatography–tandem mass spectrometry (ID-LC-MS/MS) with immunoaffinity extraction as the pretreatment method, which was validated and determined the content of aflatoxin M1 in milk powder accurately. The homogeneity was studied by analyzing in triplicate for their aflatoxin M1 contents by ID-LC-MS/MS using random sampling schemes. The short-term stability was evaluated at three different storage temperatures (4, 25 and 50 °C) for 0, 3, 5, 7, 14 days, the long-term stability study comprised of measurement after 0, 1, 3, 6, 9, 12 months after storage at 4 °C, and then, analyses were investigated by ID-LC-MS/MS. After the combination determination of 8 laboratories, the final quantity value and expanded uncertainty of matrix reference material of aflatoxin M1in milk powder were: 0.49 ± 0.11 μg/kg, k = 2, P = 0.95, and the matrix reference material is homogenous and stable at 4 °C for at least 12 months, which can provide quality assurance for the later detection accuracy.

The acidified single-walled carbon nanotubes (SWCNTs) were self-assembled on graphene oxide (GO) and then ultrasonically dispersed in a copolymer, Nafion solution, to form a GO/SWCNTs-Nafion polymer nanocomposite, which was employed to modify glassy carbon electrode (GCE). The surface morphological characteristics of different modified electrodes including bare GCE, GO-Nafion/GCE, and GO/SWCNTs-Nafion/GCE were imaged by scanning electron microscopy. For comparison, the differential pulse voltammetry and cyclic voltammetry behaviors were investigated, showing that the GO/SWCNTs-Nafion polymer composite has strong enhancement effect towards oxidation of clenbuterol (CLB). And the corresponding mechanism has been well discussed. During the reaction process, the anilino group of CLB molecule (1) was firstly oxidized to form a radical cation (2), exhibiting a characteristic oxidation peak (I) at 0.95 V, then two radical cations reacting via head-to-head coupling to form a diphenylamine intermediate (3), which was transformed into a CLB dimmer (4) through an azo bond by intramolecular electrons transferring under low potential, exhibiting a pair of reversible oxidation peak (II) and reduction peak (III). Under the optimum conditions, the composite modified electrode showed linear response to CLB in a concentration range of 1.0 × 10−8~6.0 × 10−6 mol/L with a detection limit of 6.0 × 10−9 mol/L. The modified electrode possessed good selectivity, reproducibility, and stability. In comparison with two routine analytical methods like ELISA kit and high-performance liquid chromatography (HPLC), the electrode can be successfully applied to determination of content of CLB in pig meat and pig liver samples with a recovery rate of 96.4~104.2%, suggesting a promising application in food security field.

A strong correlation exists between inflammatory bowel disease (IBD) and oxidative stress involving alterations of several key signaling pathways. It is known that methionine promotes reactive oxygen species (ROS) production; we therefore hypothesize that a methionine restriction diet would reduce ROS production, inflammatory responses, and the course of IBD. We generated a murine colitis model by dextran sodium sulfate (DSS) treatment and tested the effects of the methionine restriction diet. Forty-eight mice were randomly divided into four groups of equal size, which included a control (CON) group, an MR (methionine restriction diet) group, a DSS treated group and an MR-DSS treated group. Mice in the first two groups had unrestricted access to water for one week. Mice in the two DSS-treated groups had unrestricted access to 5% DSS solution supplied in the drinking water for the same period. Mice in the CON and DSS groups were given a basal diet, whereas mice in the MR-DSS and MR groups were fed a 0.14% MR diet. We found that DSS reduced daily weight gain, suppressed antioxidant enzyme expression, increased histopathology scores and activated NF-κB and nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) signaling. We also showed that the MR diet upregulated catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities, decreased myeloperoxidase (MPO), TNF-α and IL-1β, and reversed activation of the NF-κB signaling pathway in MR-DSS mice. Taken together, our results imply that the MR diet may be considered as an adjuvant in IBD therapeutics.

Escherichia coli strain SEC470 is a diarrhea-causing strain, isolated from a piglet experiencing serious diarrhea in Jingxi Province, China. Here, we present the draft genome of this strain, which provides the genetic basis for exploring the mechanism of enterotoxigenic E. coli infections.

Bacillus subtilis strain NKYL29 is an antimicrobial-peptide-producing strain isolated from the soil of Ranzhuang Tunnel in Hebei Province, China. Here, we present the draft genome of this strain, which provides the genetic basis for application of the antimicrobial peptide.

Porcine circovirus (PCV) is the smallest animal virus so far and has two serotypes. PCV1 is nonpathogenic, but PCV2 is pathogenic and causes post-weaning multisystemic wasting syndrome (PMWS). Factors to induce PMWS include immunity and infection status of sows, infection time, mixed infection, PCV2 variants, physical status of gilts, and feeding management. For final diagnosis, histopathological changes and existence of PCV2 in lymphoid tissues are professional standards, because fluorescence quantitative RT-PCR is not enough specific or sensitive. The commercial PCV2 vaccines can reduce occurrence of PMWS and PCV-related diseases. This paper reviews recent advances in epidemiology of PCV2 as well as diagnosis and control of PMWS.

Objective:To establish cell lines which can stably express Schlafen2(Slfn2)gene and to elucidate biological functions of the gene.Methods:pEGFP-Slfn2 eukaryotic expressing vector was constructed. Control and pEGFP-Slfn2 vectos were transiently transfected into NIH/3T3 cells to observe the distribution of Slfn2 protein directly by laser scanning confocal microscopy. Control and pEGFP-Slfn2 were stably transfected into NIH/3T3 cells and G418 screening was used to obtain resistant cell strains. The expression of Slfn2 was measured by Northern blot.The growth curve and Transwell were used to analyze the effects of Slfn2 on cell proliferation and migration. Results:By establishing cell lines which could express Slfn2 stably,it was shown that the proteins expressed by the gene were detected in cell nucleus and cytoplasm. Proliferation and migration were inhibited markedly when Slfn2 was overexpressed in these cells.Conclusions: The results suggest that Slfn2 is a potential tumor suppressor gene.