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Effect of environmental stresses on the survival and cytotoxicity of Shiga toxin-producing Escherichia coli

Food Quality and Safety 2017年第2期1卷 139-146页

作者： Brian Byongkwon Yoo Yanhong Liu Vijay Juneja Lihan Huang Cheng-An Hwang Residue Chemistry and Predictive Microbiology research unit and molecular characterization of foodborne pathogens research unit Eastern Regional Research CenterAgricultural Research ServiceUnited States Department of AgricultureWyndmoorPennsylvaniaUSA Present address:Clinical and Environmental Microbiology Branch Division of Healthcare Quality and PromotionNational Center for Emerging and Zoonotic Infectious DiseasesCenters for Disease Control and Prevention1600 Clifton Rd.NEAtlantaGA 30329USA

The objective of this study was to determine the effect of environmental stresses on the cytotoxicity of Shiga toxin-producing Escherichia coli (STEC). STEC O157:H7 and six non-O157 STEC strains (O26:H11, O103:H1, O104:H4, O111:NM, O121:NM, and O145:NM) were subjected to osmotic (aw 0.95-0.98), acid (pH 4-7), and chlorine (1-5 ppm) stresses. After stress treatments, bacterial populations, expression of virulence-associated genes, and Vero-cytotoxicity were determined. Among the strains, O145:NM survived at aw 0.97 longer than other serotypes, while O111:NM was significantly more sensitive to osmotic stress. At pH 4, O103:H1 was more resistant to the stress, while O26:H11 and O111:NM had significantly less growth. For 2 ppm chlorine stress, O26:H11, O103:H1, and O145:NM had higher populations (>3 log) than other strains. Stressed strains showed a significant increase in relative gene expression levels of stx1, stx2, and eae in O103:H1, O104:H4, and O145:NM than non-stressed control. Additionally, significantly higher Vero-cytotoxicity, as indicated by lactate dehydrogenase assay, of stressed O26:H11, O103:H1, O104:H4, and O145:NM was observed. The results suggest that the growth and cytotoxicity of selected pathogenic E. coli may be enhanced after being exposed to environmental stresses.

关键词： Pathogenic Escherichia coli stress growth virulence genes Vero-cytotoxicity.

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Deconvolution of the Error Associated with Random Sampling

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Advances in Pure Mathematics 2019年第3期9卷 205-227页

作者： Peter L. Irwin Yiping He Chin-Yi Chen molecular characterization of foodborne pathogens United States Department of Agriculture Wyndmoor PA USA

In this work empirical models describing sampling error (Δ) are reported based upon analytical findings elicited from 3 common probability density functions (PDF): the Gaussian, representing any real-valued, randomly changing variable x of mean μ?and standard deviation σthe Poisson, representing counting data: i.e., any integral-valued entity’s count of x (cells, clumps of cells or colony forming units, molecules, mutations, etc.) per tested volume, area, length of time, etc. with population mean of μ?and;binomial data representing the number of successful occurrences of something (x+) out of n observations or sub-samplings. These data were generated in such a way as to simulate what should be observed in practice but avoid other forms of experimental error. Based upon analyses of 104 Δ?measurements, we show that the average Δ?() is proportional to ?(σx•μ-1;Gaussian) or ?(Poisson & binomial). The average proportionality constants associated with these disparate populations were also nearly identical (;±s). However, since ?for any Poisson process, . In a similar vein, we have empirically demonstrated that binomial-associated ?were also proportional to σx•μ-1. Furthermore, we established that, when all ?were plotted against either ?or σx•μ-1, there was only one relationship with a slope = A (0.767 ± 0.0990) and a near-zero intercept. This latter finding also argues that all , regardless of parent PDF, are proportional to σx•μ-1?which is the coefficient of variation for a population of sample means (). Lastly, we establish that the proportionality constant A is equivalent to the coefficient of variation associated with Δ?() measurement and, therefore, . These results are noteworthy inasmuch as they provide a straightforward empirical link between stochastic sampling error and the aforementioned Cvs. Finally, we demonstrate that all attendant empirical measures of Δ?a

关键词： Stochastic Sampling Error Modeling Most Probable Composition Quantitative Metagenomics Food-Borne Bacteria

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Measuring the antioxidative activities of Queso Fresco after post-packaging high-pressure processing

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Advances in Bioscience and Biotechnology 2012年第4期3卷 297-303页

作者： Moushumi Paul Jeffrey D. Brewster Diane L. Van Hekken Peggy M. Tomasula Dairy and Functional Foods research unit USDA ARS NAA ERRC 600 East Mermaid Lane Wyndmoor PA USA molecular characterization of foodborne pathogens research unit USDA ARS NAA ERRC 600 East Mermaid Lane Wyndmoor PA USA

Some milk-associated proteins are known to be nutritionally valuable and form bioactive peptides that exhibit activity against hypertension and oxidative stress. Consumption of cheeses, such as the popular Hispanic-style cheese Queso Fresco (QF), may be a vehicle for delivery of these milk-associated peptides. This paper describes the effects of high-pressure processing (HPP) on the antioxidative activity (ORAC- FL value) of water-soluble proteins extracted from QF samples. QFs were manufactured according to a commercial-make procedure using pasteurized, homogenized milk, without added starter cultures. The cheese was cut into 45 × 45 × 150 mm3 blocks, double packaged in vacuum bags, and received the following HPP treatments: 200, 400, or 600 MPa for either 0, 5, 10, or 20 min, with warming to an internal temperature of either 22℃ or 40℃ prior to HPP treatment. Results show that the core temperature of the cheese during HPP directly affects the ORAC-FL value. The activities of the lower temperature cheeses are independent of time and pressure, and have a median ORAC-FL value of 27 trolox equivalents (TE). The higher temperature cheeses have higher ORAC-FL values ranging from 21.5 to 96.0 TE;the highest activity corresponded to the cheese held at 400 MPa for the longest time under pressure (20 min). The 600 MPa cheeses increase in activity with increasing time under pressure, but are less active than the control cheese. These results indicate that processing temperature and pressure are important factors in the antioxidative activity of these QF samples and further understanding of the roles of these variables may lead to the manufacture of healthier and more nutritious cheeses and dairy products.

关键词： ORAC-FL Assay Queso Fresco Antioxidant High Pressure Processing

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Interspecific interference competition between Encarsia formosa and Encarsia sophia （Hymenoptera： Aphelinidae） in parasitizing Bemisia tabaci （Hemiptera： Aleyrodidae） on five tomato varieties

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Insect Science 2011年第1期18卷 92-100页

作者： Shu-Ting Pang Liang Wang Yan-Hong Hou Zu-Hua Shi Key Laboratory of molecular Biology of Crop pathogens and Insects Ministry of Agriculture Institute of Insect Sciences Zhejiang UniversityHangzhou China

Interspecific competition between Encarsiaformosa and Encarsia sophia, two major parasitoids of Bemisia tabaci, and the influence of five tomato varieties on competition outcome were investigated under laboratory conditions. E. formosa parasitized more B. tabaci than E. sophia when in single wasp assays on any of the tomato varieties investigated. When B. tabaei nymphs were exposed to both wasp species （either simultaneously or sequentially）, the number of B. tabaci nymphs parasitized by either wasp species was significantly decreased compared to the sole access condition. Total mortality of B. tabaci was increased when B. tabaci nymphs were exposed to both wasp species compared to only one wasp species. Thus competition between *** and E. sophia apparently reduced parasitoid offspring numbers, but not the efficiency of biological con- trol. In fact, control efficiency was enhanced in some cases, particularly on tomato variety Huangtuoyuan （HTY）. When wasps were allowed sequential access to hosts, interference occurred through host feeding by the second wasp, especially if it was E. sophia. The effect of different tomato varieties was not significant.

关键词： Bemisia tabaci Encarsia formosa Encarsia sophia Lycopersicon esculenrum interspecific competition

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Tomato yellow leaf curl virus infection of tomato does not affect the performance of the Q and ZHJ2 biotypes of the viral vector Bemisia tabaci

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Insect Science 2011年第1期18卷 40-49页

作者： Meng Li Jian Liu Shu-Sheng Liu Ministry of Agriculture Key Laboratory of molecular Biology of Crop pathogens and Insects Institute of Insect Sciences Zhejiang UniversityHangzhou China

To better understand the etiology of begomovirus epidemics in regions under invasion we need to know how indigenous and invasive whitefly vectors respond to virus infection. We investigated both direct and indirect effects of infection with Tomato yellow leaf curl virus （TYLCV） on the performance of the invasive Q biotype and the indigenous Asian ZHJ2 biotype of whitefly Bemisia tabaci. The Q biotype performed better than the ZHJ2 biotype on either uninfected or virus-infected tomato plants. However, virus-infection of host plants did not, or only marginally affected, the performance of either biotype of whiteflies in terms of fecundity, longevity, survival, development and population increase. Likewise, association of the vectors with TYLCV did not affect fecundity and longevity of the Q or ZHJ2 biotypes on cotton, a non-host of TYLCV. These results indicate that the alien Q biotype whitefly, but not the indigenous ZHJ2 biotype, is likely to become the major vector of TYLCV in the field and facilitate virus epidemics.

关键词： Bemisia tabaci performance tomato Tomato yellow leaf curl virus virusinfection

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molecular characterization and infectivity of Papaya leaf curl China virus infecting tomato in China

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第2期11卷 109-114页

作者： Hui ZHANG Xin-ying MA Ya-juan QIAN Xue-ping ZHOU Key Laboratory of molecular Biology of Crop pathogens and Insects of Ministry of Agriculture Institute of Biotechnology Zhejiang University Hangzhou 310029 China Horticultural research Institute Shanghai Academy of Agriculture Sciences Shanghai 201106 China

Papaya leaf curl China virus (PaLCuCNV) was previously reported as a distinct begomovirus infecting papaya in southern China. Based on molecular diagnostic survey, 13 PaLCuCNV isolates were obtained from tomato plants showing leaf curl symptoms in Henan and Guangxi Provinces of China. Complete nucleotide sequences of 5 representative isolates (AJ558116, AJ558117, AJ704604, FN256260, and FN297834) were determined to be 2738–2751 nucleotides, which share 91.7%–97.9% sequence identities with PaLCuCNV isolate G2 (AJ558123). DNA-β was not found to be associated with PaLCuCNV isolates. To investigate the infectivity of PaLCuCNV, an in-fectious clone of PaLCuCNV-[CN:HeNZM1] was constructed and agro-inoculated into Nicotiana benthamiana, N. tabacum Samsun, N. glutinosa, Solanum lycopersicum and Petunia hybrida plants, which induced severe leaf curling and crinkling symptoms in these plants. Southern blot analysis and polymerase chain reaction (PCR) indicated a systemic infection of test plants by the agro-infectious clone.

关键词： Papaya leaf curl China virus (PaLCuCNV) Tomato Infectivity

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Recent advances in molecular biology research of a rice pest, the brown planthopper

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Journal of Integrative Agriculture 2019年第4期18卷 716-728页

作者： BAO Yan-yuan ZHANG Chuan-xi State Key Laboratory of Rice Biology and Ministry of Agriculture Key Lab of molecular Biology of Crop pathogens and Insects Institute of Insect Sciences Zhejiang University

The brown planthopper, Nilaparvata lugens St?l, has become a major threat in tropical Asian and China since the rice green revolution of the 1960 s. Currently, insecticide application remains the primary choice for controlling this rice insect pest, but heavy use of insecticides poses dangerous risks to beneficial natural enemies and pollinators, and stimulates N. lugens reproductivity, and has caused a resurgence of the pest in the major rice-planting regions throughout Asia. Achieving the long-lasting goal of sustainable management of N. lugens requires understanding of the molecular basis of outbreaks of the pest and the development of environment-friendly pest-control strategies. Here, we review the recent molecular advances in N. lugens research on the aspects of its endosymbionts, virus transmission, insecticide resistance, and interaction between N. lugens and rice plants. We also put forward further research directions that may shed some lights on management of the rice pest.

关键词： Nilaparvata lugens endosymbionts virus transmission insecticide resistance interaction with rice biological management

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molecular characterization of a proline transporter from Chilo suppressalis

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Insect Science 2011年第5期18卷 495-502页

作者： Jia Huang Shun-Fan Wu Gong-Yin Ye State Key Laboratory of Rice Biology Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects Instituteof Insect Sciences Zhejiang University Hangzhou China

Proline plays an important role in regulating synaptic neurotransmission in both mammalian and insect nervous systems. The full-length complementary DNA sequences encoding the proline transporter gene （CsProT） and its alternative spliced transcript （CsProT-ST） were cloned from the striped stem borer （SSB）, Chilo suppressalis, one of the most important rice pests in Asia. The comparison of amino acid sequences showed that CsProT is highly similar to the proline transporter isolated from Manduca sexta （MasProT）. The developmental changes of the relative messenger RNA expression levels of CsProT and CsProT-ST genes were examined in SSB. The expression level of CsProT-ST is much higher than that of CsProT in all developmental periods, suggesting that the Y-end spliced variant is the major transcript instead of CsProT. The highest ex- pression level of both genes in the pupal stage means that proline may be involved in some unclear functions in the metamorphosis from pupa to adulthood.

关键词： Chilo suppressalis mRNA expression neuromodulator proline transporter

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Two H3K36 methyltransferases differentially associate with transcriptional activity and enrichment of facultative heterochromatin in rice blast fungus

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aBIOTECH 2024年第1期5卷 1-16页

作者： Mengting Xu Ziyue Sun Huanbin Shi Jiangnan Yue Xiaohui Xiong Zhongling Wu Yanjun Kou Zeng Tao Ministry of Agriculture Key Laboratory of molecular Biology of Crop pathogens and Insects Institute of BiotechnologyZhejiang UniversityHangzhou 310058China State Key Lab of Rice Biology and Breeding China National Rice Research InstituteHangzhou 310021China

Di-and tri-methylation of lysine 36 on histone H3(H3K36me2/3)is catalysed by histone methyltransferase Set2,which plays an essential role in transcriptional *** there is a single H3K36 methyltransferase in yeast and higher eukaryotes,two H3K36 methyltransferases,Ash1 and Set2,were present in many filamentous ***,their roles in H3K36 methylation and transcriptional regulation remained *** with methods of RNA-seq and ChIP-seq,we revealed that both Ash1 and Set2 are redundantly required for the full H3K36me2/3 activity in Magnaporthe oryzae,which causes the devastating worldwide rice blast ***1 and Set2 distinguish genomic H3K36me2/3-marked regions and are differentially associated with repressed and activated transcription,***,Ash1-catalysed H3K36me2 was co-localized with H3K27me3 at the chromatin,and Ash1 was required for the enrichment and transcriptional silencing of H3K27me3-occupied *** the different roles of Ash1 and Set2,in H3K36me2/3 enrichment and transcriptional regulation on the stress-responsive genes,they differentially respond to various stresses in ***,we reveal a novel mechanism by which two H3K36 methyltransferases catalyze H3K36me2/3 that differentially associate with transcriptional activities and contribute to enrichment of facultative heterochromatin in eukaryotes.

关键词： Ash1 Facultative heterochromatin H3K36me2/3 Magnaporthe oryzae Set2 Transcriptional regulation

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Syntheses and Insecticidal Activity of Spirocyclic Tetronic Acid Derivatives Containing Oxime Ether Moiety

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Chemical research in Chinese Universities 2020年第5期36卷 810-815页

作者： ZHAO Yang CHENG Jingli XIE Zhengang FANG Shaowei ZHAO Jinhao Ministty of Agriculture Key Laboratory of molecular Biology of Crop pathogens and Insert Institute of Pesticide and Environmental ToxicologyZhejiang UniversityHangzhou 310058P.R.China

In order to develop novel spirocyclic tetronic acid lead compounds,a series of new spirocyclic tetronic acid derivatives containing oxime ether moiety was synthesized and *** stmctures of 16 target compounds were characterized by lH NMR spectra,13C NMR spectra and high-resolution mass spectrometer(HRMS).Preliminary bioassays indicated that most of the title compounds displayed excellent insecticidal activity against Aphis fabae and Nilapmyata lugens at 100 mg/*** particular,compound 6k showed the similar activity(LC50=6.87 mg/L)against *** as the spirotetramat(LC50=4.56 mg/L)and had better efIects(LC50=l.64 mg/L)against *** in comparison with spirotetramat(LC5o=7.90 mg/L).The study showed that compound 6k exhibited more promising and broad-spectrum insecticide activity and may serve as a new insecticidal agent for sucking pests.

关键词： Spirocyclic tetronic acid derivative Insecticidal activity Oxime ether moiety

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