Ultrastructural observations of Beauveria bassiana infection in Xylotrechus rusticus larvae

Jun‐Nan Ding,De-Fu CHI 한국곤충학회 2018 Entomological Research Vol.48 No.3

In the present study we investigated the infection process of Beauveria bassiana on Xylotrechus rusticus larvae using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM results showed that B. bassiana spores germinated on the surface of the larval body and invaded the larva as an appressorium. The hyphae then germinated from the spores and spread throughout the larval body. After the death of the larva, conidiophores formed at one end of the hypha on the surface of the larval body and prepared for a new round of infection. The TEM results showed severe damage to the larval cuticle after hyphae infection. The structure of the cuticle became thinner and eventually flocculent; muscle tissues were dissociated and eventually stuck to the hyphae, and the corpus adiposum was loose and deformed, and eventually degraded.

Identification of highly pathogenic Beauveria bassiana strain against Pieris rapae larvae

Jun‐Nan Ding,Yong-cai LAI 한국곤충학회 2018 Entomological Research Vol.48 No.5

Seven different strains of Beauveria bassiana were used in a bioassay on Pieris rapae larvae. The results showed that an B. bassiana strain showed relatively high pathogenicity towards P. rapae larvae. The adjusted mortality rate was 92.86 %, and the infection rate was 85.71 % in 10 days post inoculation. Molecular identification was performed to identify the unknown strain. Internal Transcribed Spacer sequence analysis showed that the polymerase chain reaction amplicon length of the unknown strain of Beauveria sp. was 573 bp, and sequence similarity to the known B. bassiana sequences in the NCBI database was 99 %. The B. bassiana strain was named Bb01. The changes of proteins and PPO of P. rapae larvae infected by B. bassiana Bb01 strain at different times was determined. The activity of PPO increased in 1–6 d and decreased in 7 d again after inoculation. The B. bassiana invaded into the insect body affected the balance of the proteins and PPO.

Overexpression of CXCL2 inhibits cell proliferation and promotes apoptosis in hepatocellular carcinoma

( Jun Ding ),( Kangdi Xu ),( Jie Zhang ),( Bingyi Lin ),( Yubo Wang ),( Shengyong Yin ),( Haiyang Xie ),( Lin Zhou ),( Shusen Zheng ) 생화학분자생물학회(구 한국생화학분자생물학회) 2018 BMB Reports Vol.51 No.12

C-X-C motif chemokine ligand 2 (CXCL2) is a small secreted protein that exhibits a structure similar to the proangiogenic subgroup of the CXC chemokine family. Recently, accumulating evidence suggests that chemokines play a pivotal role in cancer progression and carcinogenesis. We examined the expression levels of 7 types of ELR+ CXCLs messenger RNA (mRNA) in 264 clinical samples. We found that CXCL2 expression was stably down-regulated in 94% of hepatocellular carcinoma (HCC) specimens compared with paired adjacent normal liver tissues and some HCC cell lines. Moreover, CXCL2 overexpression profoundly attenuated HCC cell proliferation and growth and induced apoptosis in vitro. In animal studies, we found that overexpressing CXCL2 by lentivirus also apparently inhibited the size and weight of subcutaneous tumours in nude mice. Furthermore, we demonstrated that CXCL2 induced HCC cell apoptosis via both nuclear and mitochondrial apoptosis pathways. Our results indicate that CXCL2 negatively regulates the cell cycle in HCC cells via the ERK1/2 signalling pathway. These results provide new insights into HCC and may ultimately lead to the discovery of innovative therapeutic approaches of HCC. [BMB Reports 2018; 51(12): 630-635]

Biochemical Characterization of a GDSL-Motif Esterase from Bacillus sp. K91 with a New Putative Catalytic Mechanism

( Jun Mei Ding ),( Ting Ting Yu ),( Lian Ming Liang ),( Zhen Rong Xie ),( Yun Juan Yang ),( Jun Pei Zhou ),( Bo Xu ),( Jun Jun Li ),( Zun Xi Huang ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.11

The esterase gene Est8 from the thermophilic bacterium Bacillus sp. K91 was cloned and expressed in Escherichia coli. The monomeric enzyme exhibited a theoretical molecular mass of 24.5 kDa and an optimal activity around 50°C at pH 9.0. A model of Est8 was constructed using a hypothetical YxiM precursor structure (2O14_A) from Bacillus subtilis as template. The structure showed an α/β-hydrolase fold and indicated the presence of a typical catalytic triad consisting of Ser-11, Asp-182, and His-185, which were investigated by site directed replacements coupled with kinetic characterization. Asp-182 and His-185 residues were more critical than the Ser-11 residue in the catalytic activity of Est8. A comparison of the amino acid sequence showed that Est8 could be grouped into the GDSL family and further classified as an SGNH hydrolase. Est8 is a new member of the SGNH hydrolase subfamily and may employ a different catalytic mechanism.

Alone in the Game : Dynamic Spread of Churn Behavior in a Large Social Network a Longitudinal Study in MMORPG

Jun Ding,Daqi Gao,Xiaohong Chen 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.3

Churn is a defection from a service provider. This study explores the role of social network in customers’ churn behavior .As the saying goes; customer is the god in service-based industries. Since the cost of customer acquisition is much greater than the cost of customer retention, customer churn prediction is more and more important. So far, research on churn prediction has involved user profile factors and social factors, but the analysis lacks interpretability and predictive horizon. In this paper, for a better understanding of churn behavior in MMORPG, we use longitudinal statistical models to examine whether the churn behavior in one person is associated with the churn of his friends on a complete data set of an entire society. Discernible clusters of active persons and inactive persons are visible in the network, and the relationship between people’s churn behavior extends up to three separations. Besides, we provide quantitative evidence for the strong ties hypothesis. The higher the number of common friends two persons have, the influence between them is more significant. At last, we use mixed effects cox models to predict churn in the future. Our study can provide a long forecast horizon, it is an obvious advantage to prevent the churn of a person.

Comparative transcriptome analysis of tube feet of different colors in the sea urchin Strongylocentrotus intermedius

Jun Ding,Dan Yang,Yinan Wang,Weijie Zhang,Tingting Chen,Yaqing Chang 한국유전학회 2017 Genes & Genomics Vol.39 No.11

The Strongylocentrotus intermedius is an important commercially cultivated marine animal in China. In recent years, some individuals with diaphanous tube feet, rather than the normal red tube feet, have been observed among animals under cultivation; the basis of this phenotypic change is uncertain. In order to better understand the differences between two color tube feet of S. intermedius at the molecular level, we constructed four cDNA libraries from tube feet and coelomocytes of S. intermedius individuals with red or diaphanous tube feet. A total of 216,729,214 clean reads were assembled into 87,510 transcripts with an average size of 1677 bp. A BlastX search showed that 72,690 transcripts had significant matches in at least one target database. Expression profile analysis was performed on the four libraries and many differentially expressed genes were identified. Using gene enrichment analysis, several biological processes related to immune responses as well as immune-related candidate genes were identified. A total of 1694 genes were immune-related, and the genes expression of red tube feet were higher than that of diaphanous tube feet. In addition, 50,427 simple sequence repeats were obtained from the S. intermedius transcriptomes, while 32,650 and 42,264 single nucleotide polymorphisms were found in S. intermedius with diaphanous tube feet and red tube feet, respectively. These results provide valuable information for the future studies involving marker-assisted breeding and the studies of population genetics and genomics on S. intermedius.

Numerical simulation of displacement instabilities of surface grooves on an alumina forming alloy during thermal cycling oxidation

Jun Ding,Feng-Xun Li,Ki-Ju Kang 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8

Displacement instability of the thermally grown oxide (TGO) is a fundamental source of failure in thermal barrier systems. In this work, a finite element analysis has been performed to analyze the displacement instability occurring at a heat resistant metal with superficial TGO subjected to thermal cycling. Lateral and in-plane growth of the TGO which happens during high temperature is simulated by means of material property change from the substrate metal to the TGO. Most of the material properties including the TGO growth are based on the results experimentally obtained in-house. Results of the finite element analyses agree well with the experimental observation, which proves the accuracy and validity of this simulation. The technique will be useful for future work on more complicated phenomena such as deformation under thermo-mechanical cycling.

Voltage Regulation System based on ADRC for Doubly Salient Electro-magnetic Generator

Jun Ding,Weili Dai,Hao Tian,Juntao Fei 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

A voltage regulation system based on linear active disturbance rejection control (LADRC) for doubly salient electro-magnetic generator (DSEG) was proposed in this paper. Based on mathematical model and operation principle of the generator, second-order LADRC controller was constructed to keep output dc voltage stable by adjusting exciting current and corresponding operation principle was analyzed in detail. Then, control parameters selection method has been given according to engineer design consideration. Finally, co-simulation models of voltage regulation system for DSEG using LADRC and traditional output voltage feedback plus exciting current feed-forward control were built by electromagnetic finite element analysis and transient solver of control circuit. The steady state and dynamic performance of the generator under different load show that DSEG using LADRC will acquire much better steady and dynamic response characteristic than one using traditional control.

Numerical Simulation for TGO Crack Propagation near a surface groove in an Alumina Forming Alloy upon Thermo-Mechanical loading Cycles

Ding Jun,F.X. Li,Ki-Ju Kang 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

In this work, the nucleation and propagation of crack in thermally grown oxide (TGO) due to displacement instability of the surface groove in Fecralloy substrate, subjected to multiple thermo-mechanical loading cycles, has been studied using the finite element method. Assumptions and referring about the material properties are minimized for rigorous reality. Most of the material properties including TGO growth and yield strength for TGO and substrate are based on the results experimentally obtained in-house. The material property change method is employed to model TGO formation cycle by cycle, and the creep properties for constituent materials are also incorporated. Based on the finite element procedure developed by ourselves, double nodes at the same locations are placed along the interface of the potential crack initiation, and these nodes are tied together as one node at the location. The first simulation aims at identifying the node at which the stress exceeds the critical stress of TGO material, and then releasing the nodes to the target node ahead for modeling the crack propagation. The progress repeats many times until a through crack was initiated in TGO films. The result shows that the simulation can agree acceptably with the experiment and reproduce the initiation and propagation of crack in TGO increasingly.

Numerical Analysis for the Evolution of Surface Morphology of an Alumina Forming Alloy during Thermal-Mechanical Cycling

Ding Jun,F.X. Li,Anette M. Karlsson,Ki-Ju Kang 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Morphology change in surface grooves embedded in the TGO forming material substrate is a fundamental source of failure in some thermal barrier systems. In this work, the morphology instabilities on Fecralloy substrate due to the thermal-mechanical loading cycles has been explored with the variation of mechanical load. Assumptions and referring about the material properties are minimized for rigorous reality. Most of the material properties including TGO growth are based on the results experimentally obtained in-house. Employed on the finite element procedures developed by ourselves, the effects of creep of TGO and substrate on the morphology of surface grooves have been investigated. Comparison made between presence of creep and absence of creep consideration in finite element analysis shows that the creep deformation plays a central role in the displacement instabilities of TGO under thermal-mechanical loading cycles especially for the case of the relatively small magnitude of mechanical loading.