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Search Results: 1 - 10 of 23259 matches for " Mingxiong He "
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Functional Characterization of CRISPR-Cas System in the Ethanologenic Bacterium Zymomonas mobilis ZM4  [PDF]
Ge Dong, Mingxiong He, Hong Feng
Advances in Microbiology (AiM) , 2016, DOI: 10.4236/aim.2016.63018
Abstract: CRISPR-Cas (clustered regularly interspaced short palindromic repeats—CRISPR associated proteins) is a RNA-guided defense immune system that prevents some genetic elements such as plasmids and virus from getting into the bacterial cells. Zymomonas mobilis is an ethanologenic bacterium, which encodes a subtype I-F CRISPR-Cas system containing three CRISPR loci and a far distant cas gene cluster. Reverse transcription (RT)-PCR analysis revealed that the CRISPR loci were transcribed on both strands. The Cas proteins were suggested to be expressed based on the previous transcriptomic analysis. Challenging with the invader plasmids containing the artificial protospacer with the protospacer adjacent motif (PAM) of NGG or GG exhibited immune interference activity. However, PAM motif of GG seems more effective than NGG in interference activity. Further, the artificial CRISPR arrays with the spacer sequences targeting to the specific genome sites could also lead to strong immune activity, resulting in almost no transformant grown on the agar plates. It was suggested that bacteria like Z. mobilis ZM4 are lack of the rejoining function to heal the double breakage of genomic DNA made by the CRISPR system. Conclusively, the Type I-F CRISPR-Cas system in Z. mobilis ZM4 is active to functionally defense the invading DNA elements.

Yang Mijia,Chen Mingxiong,He Yongnian College of Water Conservancy,Hydropower Engineering,Hohai University,Nanjing China,

岩石力学与工程学报 , 2001,
Abstract: Grouting is a strengthening method which uses cement or other materials to fill up the fractures and voids in rock masses. As a result, the stability is improved and the permeability is reduced. But for the practical engineering, the grouting effect can be varied from very strong to very limited. As the effectiveness of grouting depends very much on the understanding of grouting process, it is important to research the process considering fractures and its connected structure in rock masses and also the non-Newtonian nature of the grouting. The final grouting reinforcement effect also depends on the enhanced strength or deformability of the fractures or grouted rock masses. Based on the grouting theories, testing researches and monitoring of grouting effect, some important points needed to research are pointed out, and the developing direction of grouting technology researches in future is also demonstrated.
Joint Power Splitting and Secure Beamforming Design in the Multiple Non-regenerative Wireless-powered Relay Networks
Mingxiong Zhao,Xiangfeng Wang,Suili Feng
Mathematics , 2015, DOI: 10.1109/LCOMM.2015.2453161
Abstract: The physical-layer security issue in the multiple non-regenerative wireless-powered relay (WPR) networks is investigated in this letter, where the idle relay is treated as a potential eavesdropper. To guarantee secure communication, the destination-based artificial noise is sent to degrade the receptions of eavesdroppers, and it also becomes a new source of energy powering relays to forward the information with power splitting (PS) technique. We propose an efficient algorithm ground on block-wise penalty function method to jointly optimize PS ratio and beamforming to maximize the secrecy rate. Despite the nonconvexity of the considered problem, the proposed algorithm is numerically efficient and is proved to converge to the local optimal solution. Simulation results demonstrate that the proposed algorithm outperforms the benchmark method.
Antioxidant Activities of Plumbagin and Its Cu (II) Complex
Mingxiong Tan,Yancheng Liu,Xujian Luo,Zhenfeng Chen,Hong Liang
Bioinorganic Chemistry and Applications , 2011, DOI: 10.1155/2011/898726
Abstract: Plumbagin and its Cu (II) complex [Cu (plumbagin)2]·H2O have been synthesized, and their antioxidant activities towards the inhibitory effect on DPPH free radical, reducing power, total antioxidant capacity, and inhibition on lipid peroxidation were investigated. Plumbagin and its Cu (II) complex were found to exhibit scavenging activities on DPPH radical with the inhibitory rate of 41% and 24%, respectively. The reducing power of plumbagin was outstanding at the concentrations of 1.0, 1.5, and 2.0?mg/mL, compared to Cu (II) complex and synthetic antioxidant 2,6-di-ter-butyl-4-methylphenol (BHT); the highest level reached 1.333 for plumbagin and 0.581 for Cu (II) complex. Also, the inhibition on lipid peroxidation of plumbagin was higher than that of Cu (II) complex and BHT, 46.4% for plumbagin and 24.5% for Cu (II) complex. The results give a strong impact for designing anticancer drugs, combined with their potential cytotoxic and antioxidant activities, which can be targeted selectively against cancer cells and increase their therapeutic index and additional advantages over other anticancer drugs. 1. Introduction Recently, a large number of metal complexes have been designed and tested for anticancer activity and for supportive therapy in cancer patients, including the anticancer drugs doxorubicin, mitoxantrone, bleomycin, and hydroxyurea [1–3]. There is a major debate at present that natural products with diverse bioactivities are becoming an important source of potential (pro)drug chelators [4, 5]. Many naturally occurring molecules such as flavonoids, phenols, and quinones have metal chelating properties, cytotoxic, and antioxidant properties, including the inhibitory effect on free radicals and other damaging oxygen activated products such as the hydroxyl radical, superoxide, hydrogen peroxide, and lipid peroxides [6, 7]. Thus, the prospect of designing chelating prodrugs can be targeted selectively and activated against cancer cells combined with their potential cytotoxic and antioxidant activities increasing their therapeutic index and provides additional advantages over other anticancer drugs [8–10]. Our earlier studies have reported the synthesis and anticancer activities of plumbagin (Scheme 1) and its Cu (II) complex (Scheme 2). Plumbagin structurally derived from naphthoquinone was extracted from Plumbago zeylanica L, a Chinese traditional medicine. It was found that both plumbagin and its Cu (II) complex exhibited significant antitumor activities against seven human tumour cell lines (BEL-7404, NCI-H460, CNE-2, 786-O, MCF-7, HCT-116, and
Fluorescence Spectroscopy Study on the Interaction between Evodiamine and Bovine Serum Albumin
Mingxiong Tan,Weijiang Liang,Xujian Luo,Yunqiong Gu
Journal of Chemistry , 2013, DOI: 10.1155/2013/308054
Synthesis, Cytotoxic Activity, and DNA Binding Properties of Copper (II) Complexes with Hesperetin, Naringenin, and Apigenin
Mingxiong Tan,Jinchan Zhu,Yingming Pan,Zhenfeng Chen,Hong Liang,Huagang Liu,Hengshan Wang
Bioinorganic Chemistry and Applications , 2009, DOI: 10.1155/2009/347872
Abstract: Complexes of copper (II) with hesperetin, naringenin, and apigenin of general composition [CuL2(H2O)2]?nH2O (1–3) have been synthesized and characterized by elemental analysis, UV-Vis, FT-IR, ESI-MS, and TG-DTG thermal analysis. The free ligands and the metal complexes have been tested in vitro against human cancer cell lines hepatocellular carcinoma (HepG-2), gastric carcinomas (SGC-7901), and cervical carcinoma (HeLa). Complexes 1 and 3 were found to exhibit growth inhibition of SGC-7901 and HepG2 cell lines with respect to the free ligands; the inhibitory rate of complex 1 is 43.2% and 43.8%, while complex 3 is 46% and 36%, respectively. The interactions of complex 1 and its ligand Hsp with calf thymus DNA were investigated by UV-Vis, fluorescence, and CD spectra. Both complex 1 and Hsp were found to bind DNA in intercalation modes, and the binding affinity of complex 1 was stronger than that of free ligand.
Activation of Arabidopsis Seed Hair Development by Cotton Fiber-Related Genes
Xueying Guan, Jinsuk J. Lee, Mingxiong Pang, Xiaoli Shi, David M. Stelly, Z. Jeffrey Chen
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021301
Abstract: Each cotton fiber is a single-celled seed trichome or hair, and over 20,000 fibers may develop semi-synchronously on each seed. The molecular basis for seed hair development is unknown but is likely to share many similarities with leaf trichome development in Arabidopsis. Leaf trichome initiation in Arabidopsis thaliana is activated by GLABROUS1 (GL1) that is negatively regulated by TRIPTYCHON (TRY). Using laser capture microdissection and microarray analysis, we found that many putative MYB transcription factor and structural protein genes were differentially expressed in fiber and non-fiber tissues. Gossypium hirsutum MYB2 (GhMYB2), a putative GL1 homolog, and its downstream gene, GhRDL1, were highly expressed during fiber cell initiation. GhRDL1, a fiber-related gene with unknown function, was predominately localized around cell walls in stems, sepals, seed coats, and pollen grains. GFP:GhRDL1 and GhMYB2:YFP were co-localized in the nuclei of ectopic trichomes in siliques. Overexpressing GhRDL1 or GhMYB2 in A. thaliana Columbia-0 (Col-0) activated fiber-like hair production in 4–6% of seeds and had on obvious effects on trichome development in leaves or siliques. Co-overexpressing GhRDL1 and GhMYB2 in A. thaliana Col-0 plants increased hair formation in ~8% of seeds. Overexpressing both GhRDL1 and GhMYB2 in A. thaliana Col-0 try mutant plants produced seed hair in ~10% of seeds as well as dense trichomes inside and outside siliques, suggesting synergistic effects of GhRDL1 and GhMYB2 with try on development of trichomes inside and outside of siliques and seed hair in A. thaliana. These data suggest that a different combination of factors is required for the full development of trichomes (hairs) in leaves, siliques, and seeds. A. thaliana can be developed as a model a system for discovering additional genes that control seed hair development in general and cotton fiber in particular.
Knockdown of ZNF268, which Is Transcriptionally Downregulated by GATA-1, Promotes Proliferation of K562 Cells
Yan Zeng, Wei Wang, Jian Ma, Xianguo Wang, Mingxiong Guo, Wenxin Li
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029518
Abstract: The human ZNF268 gene encodes a typical KRAB-C2H2 zinc finger protein that may participate in hematopoiesis and leukemogenesis. A recent microarray study revealed that ZNF268 expression continuously decreases during erythropoiesis. However, the molecular mechanisms underlying regulation of ZNF268 during hematopoiesis are not well understood. Here we found that GATA-1, a master regulator of erythropoiesis, repressed the promoter activity and transcription of ZNF268. Electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that GATA-1 directly bound to a GATA binding site in the ZNF268 promoter in vitro and in vivo. Knockdown of ZNF268 in K562 erythroleukemia cells with specific siRNA accelerated cellular proliferation, suppressed apoptosis, and reduced expression of erythroid-specific developmental markers. It also promoted growth of subcutaneous K562-derived tumors in nude mice. These results suggest that ZNF268 is a crucial downstream target and effector of GATA-1. They also suggest the downregulation of ZNF268 by GATA-1 is important in promoting the growth and suppressing the differentiation of K562 erythroleukemia cells.
Characterization of MicroRNA Expression Profiles and the Discovery of Novel MicroRNAs Involved in Cancer during Human Embryonic Development
Yi Lin, Yan Zeng, Fan Zhang, Lu Xue, Zan Huang, Wenxin Li, Mingxiong Guo
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069230
Abstract: MicroRNAs (miRNAs), approximately 22-nucleotide non-coding RNA molecules, regulate a variety of pivotal physiological or pathological processes, including embryonic development and tumorigenesis. To obtain comprehensive expression profiles of miRNAs in human embryos, we characterized miRNA expression in weeks 4-6 of human embryonic development using miRNA microarrays and identified 50 human-embryo-specific miRNAs (HES-miRNAs). Furthermore, we selected three non-conserved or primate-specific miRNAs, hsa-miR-638, -720, and -1280, and examined their expression levels in various normal and tumor tissues. The results show that expression of most miRNAs is extremely low during early human embryonic development. In addition, the expression of some non-conserved or primate-specific miRNAs is significantly different between tumor and the corresponding normal tissue samples, suggesting that the miRNAs are closely related to the pathological processes of various tumors. This study presents the first comprehensive overview of miRNA expression during human embryonic development and offers immediate evidence of the relationship between human early embryonic development and tumorigenesis.
hERG Potassium Channel Blockage by Scorpion Toxin BmKKx2 Enhances Erythroid Differentiation of Human Leukemia Cells K562
Jian Ma, Youtian Hu, Mingxiong Guo, Zan Huang, Wenxin Li, Yingliang Wu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0084903
Abstract: Background The hERG potassium channel can modulate the proliferation of the chronic myelogenous leukemic K562 cells, and its role in the erythroid differentiation of K562 cells still remains unclear. Principal Findings The hERG potassium channel blockage by a new 36-residue scorpion toxin BmKKx2, a potent hERG channel blocker with IC50 of 6.7±1.7 nM, enhanced the erythroid differentiation of K562 cells. The mean values of GPA (CD235a) fluorescence intensity in the group of K562 cells pretreated by the toxin for 24 h and followed by cytosine arabinoside (Ara-C) treatment for 72 h were about 2-fold stronger than those of K562 cells induced by Ara-C alone. Such unique role of hERG potassium channel was also supported by the evidence that the effect of the toxin BmKKx2 on cell differentiation was nullified in hERG-deficient cell lines. During the K562 cell differentiation, BmKKx2 could also suppress the expression of hERG channels at both mRNA and protein levels. Besides the function of differentiation enhancement, BmKKx2 was also found to promote the differentiation-dependent apoptosis during the differentiation process of K562 cells. In addition, the blockage of hERG potassium channel by toxin BmKKx2 was able to decrease the intracellular Ca2+ concentration during the K562 cell differentiation, providing an insight into the mechanism of hERG potassium channel regulating this cellular process. Conclusions/Significance Our results revealed scorpion toxin BmKKx2 could enhance the erythroid differentiation of leukemic K562 cells via inhibiting hERG potassium channel currents. These findings would not only accelerate the functional research of hERG channel in different leukemic cells, but also present the prospects of natural scorpion toxins as anti-leukemic drugs.
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