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111.
N-乙酰鸟氨酸脱酰基酶为一种新型手性拆分酶制剂,酶活性依赖于Mg2+、Mn2+、Zn2+及Co2+ 中的某种金属离子。以高表达NAOase的重组菌DH10B/argE-pHsh为研究对象,考察不同培养条件下Mg2+、Mn2+、Zn2+及Co2+ 4种离子对重组菌的生长、酶的表达活性及表达量的影响。结果发现:同种离子在不同条件下对重组菌的生长影响不大,但对酶活性影响显著。4种离子在合适浓度时皆能提高酶活性,促进强度从高到低依次为Mn2+、Mg2+、Co2+和Zn2+。在TB培养基中,Mn2+为15 mmol/L时:NAOase比酶活达到1 272.7 U/mL,是未添加时的4.67倍,激活作用显著高于其他离子。SDS-PAGE电泳实验表明4种离子的蛋白表达量基本相同。 相似文献
112.
In this paper, the localized surface plasmon resonance (LSPR) peak position of an ordered gold nanoparticles array embedded in a nematic liquid crystal (LC) media is investigated using finite-difference time-domain method. The influence of the anchoring effects between nematic LC molecules and glass substrate on the shift of LSPR wavelength is taken into account, and results are compared with the case of a perfect alignment of the LC molecules. 相似文献
113.
Liuhua Yan Qingzhe Zhai Jianing Wei Shuyu Li Bao Wang Tingting Huang Minmin Du Jiaqiang Sun Le Kang Chang-Bao Li Chuanyou Li 《PLoS genetics》2013,9(12)
In response to insect attack and mechanical wounding, plants activate the expression of genes involved in various defense-related processes. A fascinating feature of these inducible defenses is their occurrence both locally at the wounding site and systemically in undamaged leaves throughout the plant. Wound-inducible proteinase inhibitors (PIs) in tomato (Solanum lycopersicum) provide an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. Among the identified intercellular molecules in regulating systemic wound response of tomato are the peptide signal systemin and the oxylipin signal jasmonic acid (JA). The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity. Here we describe the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8) mutant, which was isolated as a suppressor of (pro)systemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera) and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. We present evidence that overexpression of TomLoxD leads to elevated wound-induced JA biosynthesis, increased expression of wound-responsive genes and, therefore, enhanced resistance to insect herbivory attack and necrotrophic pathogen infection. These results indicate that TomLoxD is involved in wound-induced JA biosynthesis and highlight the application potential of this gene for crop protection against insects and pathogens. 相似文献
114.
Xue Wang Fengting Xu Jiasen Liu Bingquan Gao Yanxin Liu Yujia Zhai Jun Ma Kai Zhang Timothy S. Baker Klaus Schulten Dong Zheng Hai Pang Fei Sun 《PLoS pathogens》2013,9(1)
Rabbit hemorrhagic disease, first described in China in 1984, causes hemorrhagic necrosis of the liver. Its etiological agent, rabbit hemorrhagic disease virus (RHDV), belongs to the Lagovirus genus in the family Caliciviridae. The detailed molecular structure of any lagovirus capsid has yet to be determined. Here, we report a cryo-electron microscopic (cryoEM) reconstruction of wild-type RHDV at 6.5 Å resolution and the crystal structures of the shell (S) and protruding (P) domains of its major capsid protein, VP60, each at 2.0 Å resolution. From these data we built a complete atomic model of the RHDV capsid. VP60 has a conserved S domain and a specific P2 sub-domain that differs from those found in other caliciviruses. As seen in the shell portion of the RHDV cryoEM map, which was resolved to ∼5.5 Å, the N-terminal arm domain of VP60 folds back onto its cognate S domain. Sequence alignments of VP60 from six groups of RHDV isolates revealed seven regions of high variation that could be mapped onto the surface of the P2 sub-domain and suggested three putative pockets might be responsible for binding to histo-blood group antigens. A flexible loop in one of these regions was shown to interact with rabbit tissue cells and contains an important epitope for anti-RHDV antibody production. Our study provides a reliable, pseudo-atomic model of a Lagovirus and suggests a new candidate for an efficient vaccine that can be used to protect rabbits from RHDV infection. 相似文献
115.
Four trinorsesquiterpenoids (1–4) were isolated from the roots of Inula racemosa and the structures of two new compounds, (4R,5S,10S)-5-hydroxy-11,12,13-trinoreudesm-6-en-8-one (1) and (4R,5R,10R)-4,15-epoxy-11,12,13-trinoreudesman-8-one (3), were elucidated by extensive spectroscopic analysis. Furthermore, the structure of compound 2a should be revised as (4R,5R,10S)-5-hydroxy-11,12,13-trinoreudesm-6-en-8-one (2) and compound 2 showed antiproliferative activity against A549, HepG2, and HT1080 cell lines with IC50 values of 3.71, 5.94, and 3.95 μg/mL, respectively. 相似文献
116.
Man-Li Liu Huan Wang Zong-Ren Wang Yu-Fen Zhang Yan-Qiu Chen Fang-Hong Zhu Yuan-Qiang Zhang Jing Ma Zhen Li 《PloS one》2013,8(3)
Background
Besides androgens, estrogens produced in Leydig cells are also crucial for mammalian germ cell differentiation. Transforming growth factor-β1 (TGF-β1) is now known to have multiple effects on regulation of Leydig cell function. The objective of the present study is to determine whether TGF-β1 regulates estradiol (E2) synthesis in adult rat Leydig cells and then to assess the impact of TGF-β1 on Cx43-based gap junctional intercellular communication (GJIC) between Leydig cells.Methodology/Principal Findings
Primary cultured Leydig cells were incubated in the presence of recombinant TGF-β1 and the production of E2 as well as testosterone (T) were measured by RIA. The activity of P450arom was addressed by the tritiated water release assay and the expression of Cyp19 gene was evaluated by Western blotting and real time RT-PCR. The expression of Cx43 and GJIC were investigated with immunofluorescence and fluorescence recovery after photo-bleaching (FRAP), respectively. Results from this study show that TGF-β1 down-regulates the level of E2 secretion and the activity of P450arom in a dose-dependent manner in adult Leydig cells. In addition, the expression of Cx43 and GJIC was closely related to the regulation of E2 and TGF-β1, and E2 treatment in turn restored the inhibition of TGF-β1 on GJIC.Conclusions
Our results indicate, for the first time in adult rat Leydig cells, that TGF-β1 suppresses P450arom activity, as well as the expression of the Cyp19 gene, and that depression of E2 secretion leads to down-regulation of Cx43-based GJIC between Leydig cells. 相似文献117.
118.
Jing Lu Shengchang Xin Huan Meng Matt Veldman David Schoenfeld Chao Che Ruibin Yan Hanbing Zhong Song Li Shuo Lin 《PloS one》2013,8(4)
Polo-like kinase 1 (PLK1), one of the key regulators of mitosis, is a target for cancer therapy due to its abnormally high activity in several tumors. Plk1 is highly conserved and shares a nearly identical 3-D structure between zebrafish and humans. The initial 10 mitoses of zebrafish embryonic cleavages occur every∼30 minutes, and therefore provide a rapid assay to evaluate mitosis inhibitors including those targeting Plk1. To increase efficiency and specificity, we first performed a computational virtual screen of∼60000 compounds against the human Plk1 3-D structure docked to both its kinase and Polo box domain. 370 candidates with the top free-energy scores were subjected to zebrafish assay and 3 were shown to inhibit cell division. Compared to general screen for compounds inhibiting zebrafish embryonic cleavage, computation increased the efficiency by 11 folds. One of the 3 compounds, named I2, was further demonstrated to effectively inhibit multiple tumor cell proliferation in vitro and PC3 prostate cancer growth in Xenograft mouse model in vivo. Furthermore, I2 inhibited Plk1 enzyme activity in a dose dependent manner. The IC50 values of I2 in these assays are compatible to those of ON-01910, a Plk1 inhibitor currently in Phase III clinic trials. Our studies demonstrate that zebrafish assays coupled with computational screening significantly improves the efficiency of identifying specific regulators of biological targets. The PLK1 inhibitor I2, and its analogs, may have potential in cancer therapeutics. 相似文献
119.
120.
Guo-Qiang Zhang Ke-Wei Liu Li-Jun Chen Xin-Ju Xiao Jun-Wen Zhai Li-Qiang Li Jing Cai Yu-Yun Hsiao Wen-Hui Rao Jie Huang Xue-Yong Ma Shih-Wen Chung Lai-Qiang Huang Wen-Chieh Tsai Zhong-Jian Liu 《PloS one》2013,8(4)