Establishment and comparison of in situ detection models for foodborne pathogen contamination on mutton based on SWIR-HSI.

Introduction: Rapid and accurate detection of food-borne pathogens on mutton is of great significance to ensure the safety of mutton and its products and the health of consumers. Objectives: The feasibility of short-wave infrared hyperspectral imaging (SWIR-HSI) in detecting the contamination status and species of Escherichia coli (EC), Staphylococcus aureus (SA) and Salmonella typhimurium (ST) contaminated on mutton was explored. Materials and methods: The hyperspectral images of uncontaminated and contaminated mutton samples with different concentrations (108, 107, 106, 105, 104, 103 and 102 CFU/mL) of EC, SA and ST were acquired. The one dimensional convolutional neural network (1D-CNN) model was constructed and the influence of structure hyperparameters on the model was explored. The effects of different spectral preprocessing methods on partial least squares-discriminant analysis (PLS-DA), support vector machine (SVM) and 1D-CNN models were discussed. In addition, the feasibility of using the characteristic wavelength to establish simplified models was explored. Results and discussion: The best full band model was the 1D-CNN model with the convolution kernels number of (64, 16) and the activation function of tanh established by the original spectra, and its accuracy of training set, test set and external validation set were 100.00, 92.86 and 97.62%, respectively. The optimal simplified model was genetic algorithm optimization support vector machine (GA-SVM). For discriminating the pathogen species, the accuracies of SVM models established by full band spectra preprocessed by 2D and all 1D-CNN models with the convolution kernel number of (32, 16) and the activation function of tanh were 100.00%. In addition, the accuracies of all simplified models were 100.00% except for the 1D-CNN models. Considering the complexity of features and model calculation, the 1D-CNN models established by original spectra were the optimal models for pathogenic bacteria contamination status and species. The simplified models provide basis for developing multispectral detection instruments. Conclusion: The results proved that SWIR-HSI combined with machine learning and deep learning could accurately detect the foodborne pathogen contamination on mutton, and the performance of deep learning models were better than that of machine learning. This study can promote the application of HSI technology in the detection of foodborne pathogens on meat.

Discrimination of Minced Mutton Adulteration Based on Sized-Adaptive Online NIRS Information and 2D Conventional Neural Network.

Single-probe near-infrared spectroscopy (NIRS) usually uses different spectral information for modelling, but there are few reports about its influence on model performance. Based on sized-adaptive online NIRS information and the 2D conventional neural network (CNN), minced samples of pure mutton, pork, duck, and adulterated mutton with pork/duck were classified in this study. The influence of spectral information, convolution kernel sizes, and classifiers on model performance was separately explored. The results showed that spectral information had a great influence on model accuracy, of which the maximum difference could reach up to 12.06% for the same validation set. The convolution kernel sizes and classifiers had little effect on model accuracy but had significant influence on classification speed. For all datasets, the accuracy of the CNN model with mean spectral information per direction, extreme learning machine (ELM) classifier, and 7 × 7 convolution kernel was higher than 99.56%. Considering the rapidity and practicality, this study provides a fast and accurate method for online classification of adulterated mutton.

Evaluation of dynamic developmental processes and the molecular basis of the high body fat percentage of different proglottid types of Moniezia expansa.

BACKGROUND: Moniezia expansa (Cyclophyllidea: Anoplocephalidae) is a large species of tapeworm that occurs in sheep and cattle and inhabits the small intestine, causing diarrhea and weight declines, leading to stockbreeding losses. Interestingly, the body fat percentage of M. expansa, which lacks the ability to synthesize fatty acids, is as high as 78% (dry weight) and all of the proglottids of M. expansa exhibit a dynamic developmental process from top to bottom. The aim of this paper is to identify the molecular basis of this high body fat percentage, the dynamic expression of developmental genes and their expression regulation patterns. RESULTS: From 12 different proglottids (four sections: scolex and neck, immature, mature and gravid with three replicates), 13,874 transcripts and 680 differentially expressed genes (DEGs) were obtained. The gene expression patterns of the scolex and neck and immature proglottids were very similar, while those of the mature and gravid proglottids differed greatly. In addition, 13 lipid transport-related proteins were found in the DEGs, and the expression levels showed an increasing trend in the four proglottid types. Furthermore, it was shown that 33 homeobox genes, 9 of which were DEGs, had the highest expression in the scolex and neck section. The functional enrichment results of the DEGs were predominantly indicative of development-related processes, and there were also some signal transduction and metabolism results. The most striking result was the finding of Wnt signaling pathways, which appeared multiple times. Furthermore, the weighted gene co-expression networks were divided into 12 modules, of which the brown module was enriched with many development-related genes. CONCLUSIONS: We hypothesize that M. expansa uses lipid transport-associated proteins to transport lipids from the host gut to obtain energy to facilitate its high fecundity. In addition, homeobox genes and Wnt signaling pathways play a core role in development and regeneration. The results promote research on the cell differentiation involved in the continuous growth and extension of body structures.

Recent advances and progress in the detection of bisphenol A.

Bisphenol A (BPA) is an important industrial chemical used as a plasticizer in polycarbonate and epoxy resins in the plastic and paper industries. Because of its estrogenic properties, BPA has attracted increasing attention from many researchers. This review focuses primarily on analytical methods for BPA detection that have emerged in recent years. We present and discuss the advantages and disadvantages of sample preparation techniques (e.g., solvent extraction, solid-phase extraction, molecularly imprinted polymer solid-phase extraction, and micro-extraction techniques) and analytical methods (e.g., liquid chromatography, liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, capillary electrophoresis, immunoassay, and several novel sensors). We also discuss expected future developments for the detection of BPA. Graphical Abstract This review focuses primarily on the recent development in the detection of bisphenol A including sample pre-treatment and analytical methods.

Magnetic-nanobead-based competitive enzyme-linked aptamer assay for the analysis of oxytetracycline in food.

This study presents a novel analytical method for the detection of oxytetracycline (OTC) in complex food matrices based on a direct competitive enzyme-linked aptamer assay and magnetic separation technology. In this protocol, free OTC competed with horseradish peroxidase labeled OTC (OTC-HRP) for binding to the OTC aptamer immobilized on magnetic beads. The parameters that can affect the response, such as avidin concentration, aptamer concentration, OTC-HRP concentration, incubation temperature, incubation time, blocking agent, and binding buffer, were optimized. Under the optimal conditions, the linear range for the OTC concentration detection is 0.5-100 ng mL(-1), with a concentration of OTC needed to obtain 50 % of the maximum signal of 14.47 ng mL(-1). The limit of detection and the limit of quantitation were 0.88 and 3.40 ng mL(-1), respectively. There was no obvious cross-reactivity with most of the tetracycline pesticides. The recovery rates ranged from 71.0 to 91.2 % for the food samples, including chicken, milk, and honey, and the relative standard deviation was less than 15.0 %. The proposed method was applied to measure OTC in real samples, and was validated using high-performance liquid chromatography. This method has the advantages of magnetic separation and the concentration effect of magnetic nanoparticles, the specificity of the aptamer, and the high-throughput of microtiter plates; it offers a promising approach for the screening of OTC because it is simple, rapid, highly sensitive, and has low cost.

[mRNA transcription of translation elongation factor and primase in different segments of Moniezia expansa].

A SYBR green real-time fluorescent quantitative PCR assay was developed for detection of Moniezia expansa mRNA with its beta-tubulin as an internal control. The results showed a good linear relationship (>0.99) between the Ct value and the concentration of positive plasmid for each gene from scolex and various proglottids. Real-time PCR showed that the expression abundance of translation elongation factor and primase was different. In conclusion, the transcription level of translation elongation factor and primase was high in both scolex and immature segment, suggesting that they may play a role in the development of scolex and immature segment.

[Analysis of microbial diversity in rectum of calf in large-scale cattle farm].

OBJECTIVE: To analyze the diversity of bacterial community in rectum of diarrheic calves, and differences with health calves. METHODS: 16S rRNA clone libraries were constructed, positive clones were digested by Msp I and Hha I for restriction fragment length polymorphism (RFLP), and then a phylogenetic tree was depicted based on the 16S rRNA sequencing, to confirm the compose of microbe in the diarrheic calf rectum. RESULTS: The positive rate of clone was 98.75% (474/480) in diarrheic calves, the dominant bacteria included Lactobacillus (14%), Enterococcus (10%) and Escherichia (8%). The positive rate of clone was 96.45% (488/506) in health samples, the dominant bacteria included Clostridium (13%), Bifidobacterium (8%), Megasphaera (5%). CONCLUSION: Complexity and diversity of bacterial community in rectum in 2 weeks old calves had their own features, and significant increase of Lactobacillus, Enterococcus and Escherichia was found in diarrhea calves.

Gene expression profiling of in Moniezia expansa at different developmental proglottids using cDNA microarray.

Gene expression profiles of Moniezia expansa proglottids at varying developmental stages were analysed using cDNA microarray. A total of 4,056 spots, including full length and partial complementary DNAs that represent novel, known, and control genes, were studied. Results indicated an up-regulation of 55 genes in immature proglottids, 134 genes in mature proglottids and 103 genes in gravid proglottids were up-regulated, and a down-regulation of 7 genes in immature proglottids, 68 genes in mature proglottids and 78 genes in gravid proglottids compared to controls (scolex-neck proglottids). Many of these genes were identified as transcription factors and were involved in functions such as metabolism, transport, protein biosynthesis, apoptosis, cell differentiation, cell communication and nucleic acid binding. Expression level alterations in UBE2A, Cavß, RAD51, DAZ, PKAc and 2 unknown genes were confirmed by real-time quantitative polymerase chain reaction (RT-PCR). The complete microarray data set has been deposited in the NCBI Gene Expression Omnibus, GEO Series accession number GSE13982. Results provide a gene expression profile at various development stages of M. expansa proglottids, which prove invaluable in understanding the pathogenesis of the tapeworm and studying the genes concerned with reproductive organ development.

Characterization of a Moniezia expansa ubiquitin-conjugating enzyme E2 cDNA.

Ubiquitin and other ubiquitin-like proteins play important roles in post-translational modification. They are phylogenetically well-conserved in eukaryotes. Here we report a new ubiquitin-conjugating enzyme E2 cDNA, which containing a ubiquitin-conjugating enzyme UBCc-domain named UBE2AM. Its cDNA is 899 base pairs in length and contains an open reading frame from nucleotide 171 to 632 encoding 153 amino acids. The result of real time RT-PCR showed that UBEA2 M is expressed in most of M. expansa proglottides and over-expressed in the mature proglottides. Comparison of predicted UBE2AM with UBCc (protein) homologues/orthologous from other species revealed identities between species varying from 97.5 to 99.4% at the amino acid level. Phylogenetic analysis showed the UBE2AM is a member of the eukaryotic UBCc superfamily, which have diverged from a common ancestor and the gene is clustered in the same group with the ubiquitin-conjugating enzyme E2A-like protein from Taenia asiatica.

[Detecting hematolysis of Enterococcus from sheep].

OBJECTIVE: To characterize hematolysis of Enterococcus from sheep. METHODS: Using plate assay (PA), contact hemolysis (CH), supernatant assay (SA), culture hemolysis (CLH) and PCR, we studied hemolysis characteristics of 11 Enterococcus clinical isolates, 30 isolates from healthy sheep, a standard G-Streptococcus and a standard Enterococcus. RESULTS: Rabbit blood and sheep blood were not hemolysising in the 11 clinical isolates analyzed by SA and CH. Of the clinical isolates 63.6% had beta-hemolysis with rabbit blood and 36.4% had ALPHA-hemolysis with sheep blood analyzed by PA and CLH assay. Of the cylA gene 63.6% was detected in clinical isolates, the sequence of cylA gene was 99.3% homologous with cylA of plasmid pAD1 (GenBank accession number: L37110). J-hemolysis had 53.3% in rabbit blood, alpha-hemolysis and beta-hemolysis in sheep blood had 53.3% and 43.3% respectively in 30 healthy sheep initial isolates with PA. Only 6% had hemolytic capacity in rabbit blood after second generations. The cylA gene was not detected in 30 healthy sheep isolates by PCR. Standard Enterococcus strain of alpha-hemolysis of sheep blood had no hemolysis of rabbit blood. CONCLUSION: The red blood cells could induce enterococci hemolysis secreting in the bacteria growth. The result was different with the Phenotype and the Genotype.