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A common evolutionary pathway for maintaining quorum sensing in Pseudomonas aeruginosa
Bai-min Lai,Hui-cong Yan,Mei-zhen Wang,Na Li,Dongsheng Shen 한국미생물학회 2018 The journal of microbiology Vol.56 No.2
In the bacterium Pseudomonas aeruginosa, the synthesis and secretion of extracellular protease is a typical cooperative behavior regulated by quorum sensing. However, this type of cooperative behavior is easily exploited by other individuals who do not synthesize public goods, which is known as the “tragedy of the commons”. Here P. aeruginosa was inoculated into casein media with different nitrogen salts added. In casein broth, protease (a type of public good) is necessary for bacterial growth. After 30 days of sequential transfer, some groups propagated stably and avoided “tragedy of the commons”. The evolved cooperators who continued to synthesize protease were isolated from these stable groups. By comparing the characteristics of quorum sensing in these cooperators, an identical evolutionary pattern was found. A variety of cooperative behaviors regulated by quorum sensing, such as the synthesis and secretion of protease and signals, were significantly reduced during the process of evolution. Such reductions improved the efficiency of cooperation, helping to prevent cheating. In addition, the production of pyocyanin, which is regulated by the RhlIR system, increased during the process of evolution, possibly due to its role in stabilizing the cooperation. This study contributes towards our understanding of the evolution of quorum sensing of P. aeruginosa.
Anomalous magnetization jumps in granular Pb superconducting films
Zhang An-Lei,Jiang Wan-Yan,Chen Xing-Hong,Zhang Xiao-Ke,Lu Wen-Lai,Chen Fei,Feng Zhen-Jie,Cao Shi-Xun,Zhang Jin-Cang,Ge Jun-Yi 한국물리학회 2022 Current Applied Physics Vol.35 No.-
In granular superconductors, the grain boundaries are closely related to the vortex dynamics and the macroscopic superconducting properties. In our research, Pb films with different grain sizes were prepared by tuning the substrate temperature. With the grain size decreasing, Pb films are prone to feature the anomalous magnetization jumps in the M − T curves, while in the M − H curves flux avalanche happens. Both phenomena appear in the same region of the H − T phase diagram and thus are considered to have the same origin. The further theoretical analysis shows that with grain size decreasing the pinning mechanism evolves from a mixed δTc and δl pinning to the δl pinning mechanism. The results shed light on the study of pinning mechanism for granular superconductors and is beneficial to the potential application of manipulating vortex pinning by regulation of intrinsic defects.
Ning Xue,Jian-Hua Lin,Shan Xing,Dan Liu,Shi-Bing Li,Yan-Zhen Lai,Xue-Ping Wang,Min-Jie Mao,Qian Zhong,Mu-Sheng Zeng,Wan-Li Liu 대한암학회 2019 Cancer Research and Treatment Vol.51 No.1
Purpose The purpose of this study was to identify novel plasma biomarkers for distinguishing nasopharyngeal carcinoma (NPC) patients from healthy individuals who have positive Epstein-Barr virus (EBV) viral capsid antigen (VCA-IgA). Materials and Methods One hundred seventy-four plasma cytokines were analyzed by a Cytokine Array in eight healthy individuals with positive EBV VCA-IgA and eight patients with NPC. Real-time polymerase chain reaction, Western blotting, enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry were employed to detect the expression levels of macrophage migration inhibitory factor (MIF) and CC chemokine ligand 3 (CCL3) in NPC cell lines and tumor tissues. Plasma MIF and CCL3 were measured by ELISA in 138 NPC patients, 127 EBV VCA-IgA negative (VN) and 100 EBV VCA-IgA positive healthy donors (VP). Plasma EBV VCA-IgA was determined by immunoenzymatic techniques. Results Thirty-four of the 174 cytokines varied significantly between the VP and NPC group. Plasma MIF and CCL3 were significantly elevated in NPC patients compared with VN and VP. Combination of MIF and CCL3 could be used for the differential diagnosis of NPC from VN cohort (area under the curve [AUC], 0.913; sensitivity, 90.00%; specificity, 80.30%), and combination of MIF, CCL3, and VCA-IgA could be used for the differential diagnosis of NPC from VP cohort (AUC, 0.920; sensitivity, 90.00%; specificity, 84.00%), from (VN+VP) cohort (AUC, 0.961; sensitivity, 90.00%; specificity, 92.00%). Overexpressions of MIF and CCL3 were observed in NPC plasma, NPC cell lines and NPC tissues. Conclusion Plasma MIF, CCL3, and VCA-IgA combination significantly improves the diagnostic specificity of NPC in high-risk individuals.