Improvement of Wuyiencin Biosynthesis in Streptomyces wuyiensis CK-15 by Identification of a Key Regulator, WysR

( Yanyan Liu ),( Hojin Ryu ),( Beibei Ge ),( Guohui Pan ),( Lei Sun ),( Kyungseok Park ),( Kecheng Zhang ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.12

Wuyiencin is produced by Streptomyces ahygroscopicus var. wuyiensis CK-15 and is widely used as an antifungal agent in agriculture. Analysis of wuyiencin biosynthetic gene clusters reveals wysR, a member of the LAL-family of transcriptional regulatory genes. WysR consists of an Nterminal PAS domain and a LuxR family C-terminal helix-turn-helix motif. However, the roles of wysR in wuyiencin biosynthesis are largely unknown. In this study, we showed that inactivation of wysR resulted in the complete loss of wuyiencin production, which could be restored by complementation with a single copy of wysR. Furthermore, we successfully increased wuyiencin production to a significantly higher level by overexpression of wysR in S. wuyiensis CK-15. Quantitative real-time RT-PCR analysis showed that WysR regulates wuyiencin biosynthesis by modulating other putative regulatory genes. Thus, WysR was identified as an activator of wuyiencin biosynthesis, and overexpression of wysR gene proved to be an effective strategy for improving wuyiencin production.

The effect of the HRB linker of Newcastle disease virus fusion protein on the fusogenic activity

Liu Yaqing,Liu Ying,Huang Yanan,Wen Hongling,Zhao Li,Song Yanyan,Wang Zhiyu 한국미생물학회 2021 The journal of microbiology Vol.59 No.5

Newcastle disease, designated a class A disease of poultry by the Office international des epizooties (OIE), is an acute infection caused by Newcastle disease virus (NDV). The merging of the envelope of NDV with the membrane of a target host cell is the key step in the infection pathway, which is driven by the concerted action of two glycoproteins: haemagglutinin- neuraminidase (HN) and fusion (F) protein. When the HN protein binds to the host cell surface receptor, the F protein is activated to mediate fusion. The three-dimensional structure of the F protein has been reported to have low electron density between the DIII domain and the HRB domain, and this electron-poor region is defined as the HRB linker. To clarify the contributing role of the HRB linker in the NDV F protein-mediated fusion process, 6 single amino acid mutants were obtained by site-directed mutagenesis of the HRB linker. The expression of the mutants and their abilities to mediate fusion were analysed, and the key amino acids in the HRB linker were identified as L436, E439, I450, and S453, as they can modulate the fusion ability or expression of the active form to a certain extent. The data shed light on the crucial role of the F protein HRB linker in the acquisition of a normal fusogenic phenotype.

Room-temperature Synthesis of Cu2O Nanostructures and Their Morphology-dependent Adsorption Properties

Yanyan Xu,Ping Liu,Yanyan Cao,Yaqiu Sun,Guoying Zhang 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

Three different Cu2O nanostructures, namely porous nanospheres, nanoparticles, and nanocubes, were synthesized through a facile solution route at room temperature. Structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), and nitrogen adsorption–desorption isotherms. The adsorption behavior of Methyl Orange (MO) onto these Cu2O nanostructures was investigated, considering the effect of initial methyl orange concentration and the additive amount of Cu2O products. The kinetic and equilibrium investigations suggested that the adsorption process of MO followed a pseudo-second order rate equation and the Langmuir isotherm model. The maximum adsorption capacity of the three samples followed the sequence: porous nanospheres > nanoparticles > nanocubes, which was in accordance of the BET specific surface of the samples. In addition, further investigations indicated that the as-prepared Cu2O nanostructures also show good adsorption properties for other anionic dyes including Congo red and Methyl blue.

Characterization of Extended-Spectrum β-Lactamase Genes of Shigella flexneri Isolates With Fosfomycin Resistance From Patients in China

Yanyan Liu,Yue Cheng,Haifei Yang,Li-Fen Hu,Jun Cheng,Ying Ye,Jia-Bin Li 대한진단검사의학회 2017 Annals of Laboratory Medicine Vol.37 No.5

Background: The emergence of fosfomycin resistance and extended-spectrum β-lactamase (ESBL) genes is a serious threat to public health and a new challenge in shigellosis treatment. The purpose of this study was to identify fosfomycin resistance and characterize β-lactamase genes in fos-carrying isolates of Shigella flexneri from patients in China. Methods: A total of 263 S. flexneri isolates were collected from 34 hospitals in the Anhui Province of China during September 2012-September 2015 and screened for fosA3, fosA, and fosC2 by PCR amplification and sequencing. The fos-carrying isolates were then screened for β-lactamase genes. The clonal relationships between fosA3-carrying isolates, the transmissibility of fosfomycin resistance, replicon types of plasmids carrying fosfomycin resistance genes and other associated resistance genes were investigated. Results: Twenty-five of the 263 isolates (9.5%) showed resistance to fosfomycin, and 18 (6.8%) were positive for fosA3. None of the isolates was positive for fosA or fosC2. Seventeen of the isolates carrying fosA3 (94%) were CTX-M producers (seven CTX-M-55, five CTX-M-14, and five CTX-M-123), while three (16.7%) were TEM producers (TEM-1).Sixteen (88.9%) fosA3-carrying isolates exhibited multi-drug resistance. The replicon types of the 13 fosA3-carrying plasmids were IncF (n=13), IncHI2 (n=3), IncIl-Ir (n=2), and IncN (n=1). Conclusions: Our results indicated that fosA3 could spread through plasmids in S. flexneri isolates, along with the blaCTX-M and blaTEM, which facilitate its quick dispersal. To the best of our knowledge, this is the first report of CTX-M-123-type ESBLs in S. flexneri isolates from patients in China.

Gravity balance mechanism for a spatial robotic manipulator

Yanyan Chen,Yubin Liu,Changle Li,Gangfeng Liu,Yanhe Zhu,Jie Zhao,Hegao Cai 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2

A gravity balance mechanism for spatial robotic manipulator is proposed. In this design, a parallelogram linkage mechanism, pulleys and springs are utilized to accomplish the balance. As a passive structure, it needs no motors or actuators, and safety is another great highlight of the mechanism. The balance mechanism can solve the balance problem of both planar 2-link mechanism and spatial 2-link mechanism (a roll-pitch-yaw-roll 2-link mechanism) by adding a rotational degree of freedom. This is a more simple and effective method to solve the balance problem of spatial linkage system, especially the linkage system of multi-degree of freedom joint. And the mechanism can be extended to solve a multilink balance problem.

Feedback Passivation of Switched Nonlinear Systems Using Storage-like Functions

Yanyan Liu,Goran S. Stojanovski,Mile J. Stankovski,Georgi M. Dimirovski,Jun Zhao 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.5

This paper addresses the issues of passivity and feedback passivation of switched nonlinear systems via multiple storage functions. The concept of storage-like functions for switched systems is presented. A sufficient condition for passivity of switched nonlinear systems is given via multiple storage functions under some switching signal. Then, the result is extended to find conditions under which a switched system is feedback equivalent to a passive switched system. Furthermore, passivity of switched cascade systems is investigated.

한·중 술 속담 비교 연구

류옌옌(Liu Yanyan) 한국문화융합학회 2021 문화와 융합 Vol.43 No.7

본 연구의 목적은 한국과 중국 양국의 술과 관련 속담을 비교 분석하여 공통점과 차이점을 고찰하는 데 있다. 일상생활과 밀접한 관계를 가진 술을 대상으로 선정하였기 때문에 쉽게 접할 수 있으므로 한 중 양국의 학습자들이 속담을 학습하는 과정에서 서로 술 문화를 이해하는데 도움이 될 것이다. 먼저 연구의 필요성과 목적을 기술하여 선행 연구를 검토하였다. 음식에 속하는 중요한 부부인 술 속담에 관한연구가 미흡한 점을 지적하였다. 그 다음으로 한국과 중국에서 술 관련 속담 목록을 정리하여 추출된 순서에 따라 술의 이미지, 주법과 주례, 그리고 술에 취한 속담에 담긴 교훈성으로 구분하여 분석하였다. 이를 토대로한 중 양국의 술과 관련된 속담의 공통점과 차이점을 밝히며 공통점은 과음을 삼가야 한다는 교훈적인 내용과예의를 지키며 마셔야 된다는 것을 전달하였으며, 차이점은 한국에서는 선후배와의 예의, 풍자적인 표현이 자주 나오지만 중국의 경우 친구와 사업에 관련된 주의 사항, 주도에 대한 주의사항 등을 주로 속담으로 사용한 것을 확인할 수 있었다. 마지막으로 본 연구는 주로 문화적 탐구 측면에서 한 중 술 문화의 비교 연구를 진행하므로한 중 문화 중의 술과 관련된 속담의 의미에 집중하였으며, 속담의 문장 구조나 수사법에 대해 깊이 있게 연구하지 못하였다는 한계가 있다. The purpose of this study is to examine commonalities and differences by comparing and analyzing alcohol and related proverbs in Korea and China. Since alcohol has been selected as a target that is closely related to daily life, it is easy to access, which will help foreign language learners to understand the drinking culture of both countries in the process of learning the proverb. First, the proverbs related to alcohol were analyzed by dividing them into the image of alcohol, initiation and ceremonies, and the didactic nature of the proverbs intoxicated. Based on this, the commonalities and differences of the proverbs related to alcohol were defined. In Korea, politeness with seniors and juniors and satirical expressions are frequently used in Korea, but in China, cautions related to friends and business, cautions about initiative, etc. are mainly used as proverbs could checked.

Infection of tomato by Tomato Yellow Leaf Curl Virus alters the foraging behavior and parasitism of the parasitoid Encarsia formosa on Bemisia tabaci

Xin Liu,Yanyan He,Wen Xie,Qingjun Wu,Youjun Zhang,Yong Liu,Shaoli Wang 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.2

Encarsia formosa Gahan is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies including Bemisia tabaci (Gennadius). Bemisia tabaci biotypes B and Q are two most invasive species that greatly reduce crop yields in China by feeding on plant sap and by transmitting Tomato Yellow Leaf Curl Virus (TYLCV). The effects of TYLCV infection of tomato on E. formosa foraging on B. tabaci B and Q are unknown. In Y-tube olfactometer assays in the present study, E. formosa significantly preferred TYLCVinfected tomato plants over TYLCV-free plants. The wasp females also significantly preferred TYLCV-infected tomato plants infested with 3rd-instar nymphs of B. tabaci biotype Q over TYLCV-free plants with biotype Q nymphs. However, no significant differences were observed when B. tabaci biotype B was infested on tomato plants. The oviposition bioassays confirmed that TYLCV infection on tomato plants resulted in the recruitment of parasitoids. These results indicate that TYLCV-infection of tomato increase the foraging of E. formosa on B. tabaci, as differs on the B and Q biotypes.

Identification and Characterization of NDM-1-producing Hypervirulent (Hypermucoviscous) Klebsiella pneumoniae in China

Zhou Liu,Yi Gu,Xin Li,Yanyan Liu,Ying Ye,Shihe Guan,Jiabin Li 대한진단검사의학회 2019 Annals of Laboratory Medicine Vol.39 No.2

Background: Carbapenem-resistant hypervirulent (hypermucoviscous) Klebsiella pneumoniae (CR-HMKP) poses a significant public health challenge. We investigated its epidemiology and molecular characteristics in a tertiary care hospital in eastern China. Methods: CR-HMKP were identified among 106 non-duplicated carbapenem-resistant K. pneumoniae isolates (from June 2013 to September 2017) using the string test. The pulsotype (PT) and sequence type (ST) of CR-HMKP isolates were determined using pulsed-field gel electrophoresis and multilocus sequence typing. Resistance determinants, capsular serotypes, and virulence genes were detected by PCR and sequencing. Representative isolates from each PT were selected, and their virulence phenotypes were established using the serum killing and Galleria mellonella lethality assays. Results: Of the 106 isolates, 13 (12.3%) were CR-HMKP. Seven were positive for blaNDM-1 and shared the same genotype (PT5/ST1764); the others were positive for blaKPC-2, belonged to ST11, and were divided into four different PTs. The serotype of all blaNDM-1-positive isolates was K64, while that of blaKPC-2-positive isolates were K47 (N=4) and K64 (N=2). The NDM-1-producing HMKP isolates were positive for aerobactin, exhibited high serum resistance, and elicited significantly increased larval mortality compared with the other isolates. All patients had received invasive treatment prior to infection by NDM-1-producing HMKP. The infections occurred between July and August 2016 and were hospital-acquired. Conclusions: NDM-1-producing HMKP ST1764 isolates were identified; this is the first report worldwide on an outbreak of nosocomial infection caused by these isolates. Effective surveillance and strict infection control strategies should be implemented to prevent CR-HMKP dissemination.

Study on the mixing performance of mixing vane grids and mixing coefficient by CFD and subchannel analysis code in a 5×5 rod bundle

Han Bin,Zhu Xiaoliang,Yang Bao-Wen,Liu Aiguo,Xi Yanyan,Liu Lei,Liu Shenghui,Huang Junlin 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.10

Mixing Vane Grid (MVG) is one of the most important structures in fuel assembly due to its high performance in mixing the coolant and ultimately increasing Critical Heat Flux (CHF), which avoids the temperature rising suddenly of fuel rods. To evaluate the mixing performance of the MVG, a Total Diffusion Coefficient (TDC) mixing coefficient is defined in the subchannel analysis code. Conventionally, the TDC of the spacer grid is obtained from the combination of experiments and subchannel analysis. However, the processing of obtaining and determine a reasonable TDC is much challenging, it is affected by boundary conditions and MVG geometries. In is difficult to perform all the large and costing rod bundle tests. In this paper, the CFD method was applied in TDC analysis. A typical 5 5 MVG was simulated and validated to estimate the mixing performance of the MVG. The subchannel code was used to calculate the TDC. Firstly, the CFD method was validated from the aspect of pressure drop and lateral temperature distribution in the subchannels. Then the effect of boundary conditions including the inlet temperature, inlet velocities, heat flux ratio between hot and cold rods and the arrangement of hot and cold rods on MVG mixing and TDC were studied. The geometric effects on mixing are also carried out in this paper. The effect of vane pattern on mixing was investigated to determine which one is the best to represent the grid's mixing performance.