Development of alkaline phosphatase-linked single-chain variable fragment fusion proteins for one-step immunodetection of deoxynivalenol in cereals

Deoxynivalenol (DON) is a mycotoxin that widely distributes in various foods and seriously threatens food safety. To minimize the consumers' dietary exposure to DON, there is an urgent demand for developing rapid and sensitive detection methods for DON in food. In this study, a bifunctional single-chain variable fragment (scFv) linked alkaline phosphatase (ALP) fusion protein was developed for rapid and sensitive detection of deoxynivalenol (DON). The scFv gene was chemically synthesized and cloned into the expression vector pET25b containing the ALP gene by homologous recombination. The prokaryotic expression, purification, and activity analysis of fusion proteins (scFv-ALP and ALP-scFv) were well characterized and performed. The interactions between scFv and DON were investigated by computer-assisted simulation, which included hydrogen bonds, hydrophobic interactions, and van der Waals forces. The scFv-ALP which showed better bifunctional activity was selected for developing a direct competitive enzyme-linked immunosorbent assay (dc-ELISA) for DON in cereals. The dc-ELISA takes 90 min for one test and exhibits a half inhibitory concentration (IC50) of 11.72 ng/mL, of which the IC50 was 3.08-fold lower than that of the scFv-based dc-ELISA. The developed method showed high selectivity for DON, and good accuracy was obtained from the spike experiments. Furthermore, the detection results of actual cereal samples analyzed by the method correlated well with that determined by high-performance liquid chromatography (R2=0.97165). These results indicated that the scFv-ALP is a promising bifunctional probe for developing the one-step colorimetric immunoassay, providing a new strategy for rapid and sensitive detection of DON in cereals.

Updated Review of the Toxicity of Selected Fusarium Toxins and Their Modified Forms

Mycotoxins are one of the most dangerous food and feed contaminants, hence they have significant influence on human and animal health. This study reviews the information reported over the last few years on the toxic effects of the most relevant and studied Fusarium toxins and their modified forms. Deoxynivalenol (DON) and its metabolites can induce intracellular oxidative stress, resulting in DNA damage. Recent studies have also revealed the capability of DON and its metabolites to disturb the cell cycle and alter amino acid expression. Several studies have attempted to explore the mechanism of action of T-2 and HT-2 toxins in anorexia induction. Among other findings, two neurotransmitters associated with this process have been identified, namely substance P and serotonin (5-hydroxytryptamine). For zearalenone (ZEN) and its metabolites, the literature points out that, in addition to their generally acknowledged estrogenic and oxidative potentials, they can also modify DNA by altering methylation patterns and histone acetylation. The ability of the compounds to induce alterations in the expression of major metabolic genes suggests that these compounds can contribute to the development of numerous metabolic diseases, including type 2 diabetes.

Biodegradation of Deoxynivalenol by Nocardioides sp. ZHH-013: 3-keto-Deoxynivalenol and 3-epi-Deoxynivalenol as Intermediate Products

Deoxynivalenol (DON) is one of the most devastating and notorious contaminants in food and animal feed worldwide. A novel DON-degrading strain, Nocardioides sp. ZHH-013, which exhibited complete mineralization of DON, was isolated from soil samples. The intermediate products of DON generated by this strain were identified by high-performance liquid chromatography and ultra-performance liquid chromatography tandem mass spectrometry analyses. It was shown that, on an experimental level, 3-keto-DON was a necessary intermediate product during the conversion from DON to 3-epi-DON. Furthermore, the ZHH-013 strain could also utilize 3-epi-DON. This DON degradation pathway is a safety concern for food and feed. The mechanism of DON and 3-epi-DON elimination will be further studied, so that new enzymes for DON degradation can be identified.

Biomarkers of Deoxynivalenol Toxicity in Chickens with Special Emphasis on Metabolic and Welfare Parameters

Deoxynivalenol (DON), a trichothecene mycotoxin produced by Fusarium species, is the most widespread mycotoxin in poultry feed worldwide. Long term-exposure from low to moderate DON concentrations can produce alteration in growth performance and impairment of the health status of birds. To evaluate the efficacy of mycotoxin-detoxifying agent alleviating the toxic effects of DON, the most relevant biomarkers of toxicity of DON in chickens should be firstly determined. The specific biomarker of exposure of DON in chickens is DON-3 sulphate found in different biological matrices (plasma and excreta). Regarding the nonspecific biomarkers called also biomarkers of effect, the most relevant ones are the impairment of the productive parameters, the intestinal morphology (reduction of villus height) and the enlargement of the gizzard. Moreover, the biomarkers of effect related to physiology (decrease of blood proteins, triglycerides, hemoglobin, erythrocytes, and lymphocytes and the increase of alanine transaminase (ALT)), immunity (response to common vaccines and release of some proinflammatory cytokines) and welfare status of the birds (such as the increase of Thiobarbituric acid reactive substances (TBARS) and the stress index), has been reported. This review highlights the available information regarding both types of biomarkers of DON toxicity in chickens.

Transcriptional analysis of deoxynivalenol-induced apoptosis of sow ovarian granulosa cell

Litter size is one of the most important economic traits in pig production. Recent studies identified that deoxynivalenol (DON), a widespread toxin in fodder, was associated with animal prolificacy. However, the underlying mechanisms have not yet been completely elucidated. Here, we used porcine ovary granulosa cells (pGCs) as a vector to establish DON concentration-time models and performed cell morphology and transcriptome analysis to identify and analyse the effects of DON on reproductive performance in swine. The results showed that DON can induce morphological changes and apoptosis of pGCs, while inhibiting cell proliferation. Moreover, these effects of DON on pGCs were dose-dependent. After treatment of pGCs with different concentrations of DON, the percentage of cells in S phase and G2/M phase increased. RNA-seq analyses revealed 5,937 differentially expressed genes, of which 1995 were down-regulated and 3,942 were up-regulated after DON treatment. KEGG enrichment analysis indicated important metabolic pathways such as IL-17 signalling pathway, eukaryotic ribosome synthesis pathway, RNA transport pathway and RNA degradation. Based on our results, we speculate that the effects of DON are related to the DNA damage process. Our study provides novel insights and a foundation to further understand the effect of DON on swine prolificacy.