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Genomic characteristics of Dickeya fangzhongdai isolates from pear and the function of type Ⅳ pili in the chromosome

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Journal of Integrative Agriculture 2020年第4期19卷 906-920页

作者： CHEN Bin TIAN Yan-li ZHAO Yu-qiang WANG Yuan-jie ChuAN Jia-cheng LI Xiang hu bai-shi College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests Ministry of EducationNanjing Agricultural UniversityNanjing 210095P.R.China Institute of Botany Jiangsu Province and Chinese Academy of Sciences(Nanjing Botanical Garden Mem.Sun Yat-Sen)/Jiangsu Key Laboratory for the Research and Utilization of Plant ResourcesNanjing 210014P.R.China Charlottetown Laboratory Canadian Food Inspection AgencyCharlottetownPE C1A5T1Canada

Dickeya fangzhongdai, the causal agent of bleeding canker of pear, is a new member of the Dickeya genus and the only one that infects woody plants. Recent studies have reclassified several Dickeya isolates as D. fangzhongdai, which were isolated from various environments, including water, Phalaenopsis sp. and Aglaonema sp. To provide genomic characterization of D. fangzhongdai isolates from pear, the genomes of D. fangzhongdai strain JS5(=China General Microbiological Culture Collection Center, CGMCC 1.15464 ~T=DSM 101947 ~T), along with two other isolates, LN1 and QZH3, were sequenced and compared to those of other Dickeya spp. Homology greater than 99% was observed among three D. fangzhongdai strains. Plasmid, type IV secretion system(T4 SS) and type IV pili(TFPs) were found in genomes of D. fangzhongdai isolates. Comparative analysis of the type Ⅲ secretion systems(T3 SS), type Ⅲ secretion effectors(T3 SE), plant cell wall degradation enzymes(PCWDE) and membrane transport proteins of Dickeya spp. showed some differences which might reflect the variations of virulence, phylogenetic and phenotypic characteristics of Dickeya spp. In addition, deletion mutant of TFP in D. fangzhongdai JS5 showed no twitching motility and reduced virulence and biofilm formation. The fingdings of the distinctive plasmid, T4 SS and TFPs, as well as the differences of T3 SE, PCWDE and membrane transport proteins make D. fangzhongdai isolates unique. These results also suggested that acquisition of virulence genes by horizontal gene transfer might play some role in the genetic variation of D. fangzhongdai.

关键词： Dickeya fangzhongdai comparative genomics virulence typeⅣpili

Bleeding canker of pears caused by Dickeya fangzhongdai:Symptoms,etiology and biology

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Journal of Integrative Agriculture 2020年第4期19卷 889-897页

作者： CHEN Bin TIAN Yan-li ZHAO Yu-qiang WANG Jia-nan XU Zhi-gang LI Xiang hu bai-shi College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests Ministry of EducationNanjing Agricultural UniversityNanjing 210095P.R.China Institute of Botany Jiangsu Province and Chinese Academy of Sciences(Nanjing Botanical Garden Mem.Sun Yat-Sen)/Jiangsu Key Laboratory for the Research and Utilization of Plant ResourcesNanjing 210014P.R.China Charlottetown Laboratory Canadian Food Inspection AgencyCharlottetownPE C1A5T1Canada

Bleeding canker,a devastating disease of pear trees(Pyrus pyrifolia L.),was first reported in the 1970 s in Jiangsu,China and more recently in other provinces in China.Trees infected with bleeding canker pathogen,Dickeya fangzhongdai,develop cankers on the trunks and branches,and a rust-colored mixture of bacterial ooze and tree sap could be seen all over the trunks and branches.In this study,we provided detail descriptions of the symptoms and epidemiology of bleeding canker disease.Based on pathogenic and phenotypic characterizations,we identified the causal agent of bleeding canker of pear as D.fangzhongdai.Dickeya fangzhongdai strains isolated from pear were also pathogenic on Solanum tuberosum,Brassica pekinensis,Lycopersicon esculentum,and Phalaenopsis aphrodite based on artificial inoculation,and the pathogen were more virulent on potato than that of D.solani strain.This study provides new information about this disease and bleeding canker disease of pear.

关键词： pear bleeding canker Dickeya fangzhongdai symptoms pathogenicity

Fire blight disease, a fast-approaching threat to apple and pear production in China

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Journal of Integrative Agriculture 2019年第4期18卷 815-820页

作者： ZHAO Yu-qiang TIAN Yan-li WANG Li-min GENG Guo-min ZHAO Wen-jun hu bai-shi ZHAO You-fu Jiangsu Key Laboratory for the Research and Utilization of Plant Resources Institute of Botany Jiangsu Province and Chinese Academy of Sciences (Nanjing Botanical Garden Mem. Sun Yat-Sen) College of Plant Protection Nanjing Agricultural University/Key Laboratory of Integrated Management of Crop Diseases and Pests Ministry of Education Chinese Academy of Inspection and Quarantine Department of Crop Sciences University of Illinois at Urbana-Champaign

Fire blight, caused by Erwinia amylovora, is a devastating disease of apples and pears, causing enormous economic losses around the world. The disease is indigenous to North America and has spread to more than 50 countries since its discovery in 1870 s. Recent reports of the disease in China's neighboring countries, including South Korea, Kyrgyzstan, and Kazakhstan, pose great threat to the world's leading producer of apples and pears. This mini-review intends to provide an update on the disease, pathogen biology, epidemiology, and control. It will also provide some perspectives and suggestions for the apple and pear industry and growers in China, which will face the imminent threat of this devastating disease.

关键词： fire blight Erwinia amylovora biology epidemiology disease control

The Twin-Arginine Translocation (Tat) Pathway Is Essential for Virulence,Flagellation,and Chemotaxis in Xanthomonas oryzae pv. oryzicola Strain RsGD42

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Agricultural Sciences in China 2009年第12期8卷 1482-1491页

作者： QIAN Guo-liang HAN Bing CHEN Lei hu bai-shi YANG Wan-feng WANG Chen HAN Zhi-cheng LIU Feng-quan Department of Plant Pathology College of Plant Protection Nanjing Agricultural University/Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects Ministry of Agriculture Nanjing 210095 P.R.China Lianyungang Exit and Entry Inspection and Quarantine Bureau Lianyungang 222042 P.R.China

Bacterial leaf streak, caused by Xanthomonas oryzae pv. oryzicola, is an important disease of rice （Oryza sativa）. Genetic determinants （tatABC genes） of the twin-arginine translocation （Tat） pathway from X. oryzae pv. oryzicola strain RsGD42 were cloned and characterized, meanwhile, a tatC disruption mutant was generated. The tatC mutant lacked detectable flagella and was highly impaired in motility and chemotaxis. Furthermore, it was observed that the tatC mutant exhibited a reduced production of extracellular polysaccharide （EPS） and a significant reduction of virulence on adult rice plants compared to wild type strain. However, the tatC mutation in X. oryzae pv. oryzieola strain RsGD42 did not affect the growth rate and the ability to induce hypersensitive response （HR） in nonhost tobacco （Nicotiana tabacum L. cv. Samsun）. In conclusion, the data indicated that the Tat pathway significantly contributed to the virulence of X. oryzae pv. oryzicola.

关键词： twin-arginine translocation Xanthomonas oryzae pv. oryzicola motility virulence

Frequency-comb-linearized, widely tunable lasers for coherent ranging

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Photonics Research 2024年第4期12卷 663-681页

作者： BAOQI shi YI-HAN LUO WEI SUN YUE hu JINBAO LONG XUE bai ANTING WANG JUNQIU LIU Department of Optics and Optical Engineering University of Science and Technology of ChinaHefei 230026China International Quantum Academy Shenzhen 518048China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Tunable lasers,with the ability to continuously vary their emission wavelengths,have found widespread applications across various fields such as biomedical imaging,coherent ranging,optical communications,and spectroscopy.In these applications,a wide chirp range is advantageous for large spectral coverage and high frequency resolution.Besides,the frequency accuracy and precision also depend critically on the chirp linearity of the laser.While extensive efforts have been made on the development of many kinds of frequency-agile,widely tunable,narrow-linewidth lasers,wideband yet precise methods to characterize and linearize laser chirp dynamics are also demanded.Here we present an approach to characterize laser chirp dynamics using an optical frequency comb.The instantaneous laser frequency is tracked over terahertz bandwidth at 1 MHz intervals.Using this approach we calibrate the chirp performance of 12 tunable lasers from Toptica,Santec,New Focus,EXFO,and NKT that are commonly used in fiber optics and integrated photonics.In addition,with acquired knowledge of laser chirp dynamics,we demonstrate a simple frequency-linearization scheme that enables coherent ranging without any optical or electronic linearization unit.Our approach not only presents novel wideband,highresolution laser spectroscopy,but is also critical for sensing applications with ever-increasing requirements on performance.

关键词： tunable Focus coherent

Design and mechanical properties analysis of a cellular Waterbomb origamistructure

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Theoretical & Applied Mechanics Letters 2024年第3期14卷 193-202页

作者： Yongtao bai Zhaoyu Wang Yu shi School of Civil Engineering Chongqing UniversityChongqing 400045China Research Center of Steel Structure Engineering Chongqing UniversityChongqing 400045China

Cellular structures are commonly used to design energy-absorbing structures,and origami structures are becominga prevalent method of cellular structure design.This paper proposes a foldable cellular structure based on theWaterbomb origami pattern.The geometrical configuration of this structure is described.Quasi-static compressiontests of the origami tube cell of this cellular structure are conducted,and load-displacement relationship curvesare obtained.Numerical simulations are carried out to analyze the effects of aspect ratio,folding angle,thicknessand number of layers of origami tubes on initial peak force and specific energy absorption(SEA).Calculationformulas for initial peak force and SEA are obtained by the multiple linear regression method.The degree ofinfluence of each parameter on the mechanical properties of the single-layer tube cell is compared.The resultsshow that the cellular structure exhibits negative stiffness and periodic load-bearing capacity,as well as foldingangle has the most significant effect on the load-bearing and energy-absorbing capacity.By adjusting the designparameters,the stiffness,load-bearing capacity and energy absorption capacity of this cellular structure can beadjusted,which shows the programmable mechanical properties of this cellular structure.The foldability andthe smooth periodic load-bearing capacity give the structure potential for application as an energy-absorbingstructure.

关键词： Cellular structure Waterbomb origami Mechanical metamaterial Numerical simulation Energy absorption

Nitrogen availability mediates the effects of roots and mycorrhizal fungi on soil organic carbon decomposition:A meta-analysis

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Pedosphere 2024年第2期34卷 289-296页

作者： Tongshuo bai Yunpeng QIU Shuijin hu Ecosystem Ecology Laboratory College of Resources and Environmental SciencesNanjing Agricultural UniversityNanjing 210095China Department of Entomology&Plant Pathology North Carolina State UniversityRaleigh NC 27695USA

Plant roots and their associated mycorrhizal fungi critically mediate the decomposition of soil organic carbon(C),but the general patterns of their impacts over a broad geographical range and the primary mediating factors remain unclear.Based on a synthesis of 596 paired observations from both field and greenhouse experiments,we found that living roots and/or mycorrhizal fungi increased organic C decomposition by 30.9%,but low soil nitrogen(N)availability(i.e.,high soil C:N ratio)critically mitigated this promotion effect.In addition,the positive effects of living roots and/or mycorrhizal fungi on organic C decomposition were higher under herbaceous and leguminous plants than under woody and non-leguminous plants,respectively.Surprisingly,there was no significant difference between arbuscular mycorrhizal fungi and ectomycorrhizal fungi in their effects on organic C decomposition.Furthermore,roots and/or mycorrhizal fungi significantly enhanced the decomposition of leaf litter but not root litter.These findings advance our understanding of how roots and their symbiotic fungi modulate soil C dynamics in the rhizosphere or mycorrhizosphere and may help improve predictions of soil global C balance under a changing climate.

关键词： arbuscular mycorrhizal fungi ectomycorrhizal fungi leaf litter leguminous plant mycorhizosphere rhizosphere root litter soil C:N ratio

Removal of a guide-wire sliding into abdominal cavity via transgastric natural orifice transluminal endoscopic surgery: A case report

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World Journal of Clinical Cases 2024年第3期12卷 596-600页

作者： shi-Ju Chen Da-Ya Zhang Yan-Ting Lv Fei-hu bai Graduate School Hainan Medical UniversityHaikou 571199Hainan ProvinceChina Department of Gastroenterology The Second Affiliated Hospital of Hainan Medical University570216 HaikouHainan ProvinceChina Department of Gastroenterology Clinical Medical Center of Hainan ProvinceHaikou 570216Hainan ProvinceChina

BACKGROUND Guidewire slippage into the peritoneal cavity during clinical operations is extremely rare.Therefore,this paper aims to report a successful case of guidewire removal using transgastric natural orifice transluminal endoscopic surgery(NOTES).The goal is to enhance physicians'understanding of the management plan for this unique scenario and provide a valuable reference for clinical practice.CASE SUMMARY A 64-year-old man presented with abdominal distension and was diagnosed with cirrhosis combined with massive ascites.To proceed with treatment,the patient underwent ultrasound-guided peritoneal puncture and underwent catheterization and drainage.Unfortunately,a 0.035-inch guidewire slipped into the abdominal cavity during the procedure.Following a comprehensive evaluation and consultation by a multidisciplinary team,the guidewire was successfully removed using NOTES.CONCLUSION This case highlights the potential consideration of transgastric NOTES removal when encountering a foreign body,such as a guidewire,within the abdominal cavity.

关键词： Guidewire Abdominal cavity Natural orifice transluminal endoscopic surgery Cirrhosis Massive ascites Case report

Emergence of SARS and COVID-19 and preparedness for the next emerging disease X

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Frontiers of Medicine 2024年第1期18卷 1-18页

作者： Ben hu hua Guo Haorui Si Zhengli shi CAS Key Laboratory of Special Pathogens and Biosafety Wuhan Institute of VirologyChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Severe acute respiratory syndrome(SARS)and Coronavirus disease 2019(COVID-19)are two human Coronavirus diseases emerging in this century,posing tremendous threats to public health and causing great loss to lives and economy.In this review,we retrospect the studies tracing the molecular evolution of SARS-CoV,and we sort out current research findings about the potential ancestor of SARS-CoV-2.Updated knowledge about SARS-CoV-2-like viruses found in wildlife,the animal susceptibility to SARS-CoV-2,as well as the interspecies transmission risk of SARS-related coronaviruses(SARSr-CoVs)are gathered here.Finally,we discuss the strategies of how to be prepared against future outbreaks of emerging or re-emerging coronaviruses.

关键词： SARS COVID-19 coronavirus