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931.
Chiou‐Chu Su Chung Jan Chang Che‐Ming Chang Hsien‐Tzung Shih Kuo‐Ching Tzeng Fuh‐Jyh Jan Chin‐Wen Kao Wen‐Ling Deng 《Journal of Phytopathology》2013,161(6):389-396
Characteristic symptoms of Pierce's disease (PD) in grapevines (Vitis vinifera L.) were observed in 2002 in the major grape production fields of central Taiwan. Disease severity in vineyards varied, and all investigated grape cultivars were affected. Diseased tissues were collected from fields for subsequent isolation and characterization of the causal agent of the disease (Xylella fastidiosa). Koch's postulates were fulfilled by artificially inoculating two purified PD bacteria to grape cultivars Kyoho, Honey Red and Golden Muscat. The inoculated plants developed typical leaf‐scorching symptoms, and similar disease severity developed in the three cultivars from which the bacterium was readily re‐isolated, proving that the leaf scorch of grapevines in Taiwan is caused by the fastidious X. fastidiosa. This confirmed PD of grapevines is also the first report from the Asian Continent. Phylogenetic analyses were performed by comparing the 16S rRNA gene and 16S‐23S rRNA internal transcribed spacer region (16S‐23S ITS) of 12 PD strains from Taiwan with the sequences of 13 X. fastidiosa strains from different hosts and different geographical areas. Results showed that the PD strains of Taiwan were closely related to the American X. fastidiosa grape strains but not to the pear strains of Taiwan, suggesting that the X. fastidiosa grape and pear strains of Taiwan may have evolved independently from each other. 相似文献
932.
933.
Heng Zhang Heng Zhang Zeng-Qiang Gao Wen-Jia Wang Guang-Feng Liu Jian-Hua Xu Xiao-Dong Su Yu-Hui Dong 《The Journal of biological chemistry》2013,288(8):5928-5939
The type VI secretion system (T6SS), a multisubunit needle-like apparatus, has recently
been found to play a role in interspecies interactions. The Gram-negative bacteria
harboring T6SS (donor) deliver the effectors into their neighboring cells (recipient) to
kill them. Meanwhile, the cognate immunity proteins were employed to protect the donor
cells against the toxic effectors. Tae4 (type VI
amidase effector 4) and Tai4
(type VI amidase
immunity 4) are newly identified T6SS effector-immunity pairs.
Here, we report the crystal structures of Tae4 from Enterobacter cloacae
and Tae4-Tai4 complexes from both E. cloacae and Salmonella
typhimurium. Tae4 acts as a dl-endopeptidase and displays a typical
N1pC/P60 domain. Unlike Tsi1 (type VI
secretion immunity 1), Tai4 is an
all-helical protein and forms a dimer in solution. The small angle x-ray scattering study
combined with the analytical ultracentrifugation reveal that the Tae4-Tai4 complex is a
compact heterotetramer that consists of a Tai4 dimer and two Tae4 molecules in solution.
Structure-based mutational analysis of the Tae4-Tai4 interface shows that a helix
(α3) of one subunit in dimeric Tai4 plays a major role in binding of Tae4, whereas
a protruding loop (L4) in the other subunit is mainly responsible for inhibiting Tae4
activity. The inhibition process requires collaboration between the Tai4 dimer. These
results reveal a novel and unique inhibition mechanism in effector-immunity pairs and
suggest a new strategy to develop antipathogen drugs. 相似文献
934.
Jun Liu Yan Luo Hengtao Ge Chengquan Han Hui Zhang Yongsheng Wang Jianmin Su Fusheng Quan Mingqing Gao Yong Zhang 《PloS one》2013,8(6)
The present study was conducted to determine whether recombinant human β-defensin-3 (rHBD3) in the milk of transgenic goats has an anti-bacterial activity against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Streptococcus agalactiae (S. agalactiae) that could cause mastitis. A HBD3 mammary-specific expression vector was transfected by electroporation into goat fetal fibroblasts which were used to produce fourteen healthy transgenic goats by somatic cell nuclear transfer. The expression level of rHBD3 in the milk of the six transgenic goats ranged from 98 to 121 µg/ml at 15 days of lactation, and was maintained at 90–111 µg/ml during the following 2 months. Milk samples from transgenic goats showed an obvious inhibitory activity against E. coli, S. aureus and S. agalactiae in vitro. The minimal inhibitory concentrations of rHBD3 in milk against E. coli, S. aureus and S. agalactiae were 9.5–10.5, 21.8–23.0 and 17.3–18.5 µg/mL, respectively, which was similar to those of the HBD3 standard (P>0.05). The in vivo anti-bacterial activities of rHBD3 in milk were examined by intramammary infusion of viable bacterial inoculums. We observed that 9/10 and 8/10 glands of non-transgenic goats infused with S. aureus and E. coli became infected. The mean numbers of viable bacteria went up to 2.9×103 and 95.4×103 CFU/ml at 48 h after infusion, respectively; the mean somatic cell counts (SCC) in infected glands reached up to 260.4×105 and 622.2×105 cells/ml, which were significantly higher than the SCC in uninfected goat glands. In contrast, no bacteria was presented in glands of transgenic goats and PBS-infused controls, and the SSC did not significantly change throughout the period. Moreover, the compositions and protein profiles of milk from transgenic and non-transgenic goats were identical. The present study demonstrated that HBD3 were an effective anti-bacterial protein to enhance the mastitis resistance of dairy animals. 相似文献
935.
以科尔沁沙地半固定沙丘和流动沙丘两种不同沙丘上的盐蒿(Artemisia halodendron)种群为研究对象,采用空间点格局方法研究了 0~20 m尺度上盐蒿种群的空间分布格局及其关联性.结果表明,半固定沙丘上盐蒿种群的数量远大于流动沙丘,不同生长发育阶段的种群结构呈偏正态分布,属于稳定型种群;流动沙丘上不同生长发... 相似文献
936.
Burkholderia mallei is a facultative intracellular pathogen that can cause fatal disease in animals and humans. To better understand the role of phagocytic cells in the control of infections caused by this organism, studies were initiated to examine the interactions of B. mallei with RAW 264.7 murine macrophages. Utilizing modified kanamycin-protection assays, B. mallei was shown to survive and replicate in RAW 264.7 cells infected at multiplicities of infection (moi) of ≤ 1. In contrast, the organism was efficiently cleared by the macrophages when infected at an moi of 10. Interestingly, studies demonstrated that the monolayers only produced high levels of TNF-α, IL-6, IL-10, GM-CSF, RANTES and IFN-β when infected at an moi of 10. In addition, nitric oxide assays and inducible nitric oxide synthase (iNOS) immunoblot analyses revealed a strong correlation between iNOS activity and clearance of B. mallei from RAW 264.7 cells. Furthermore, treatment of activated macrophages with the iNOS inhibitor, aminoguanidine, inhibited clearance of B. mallei from infected monolayers. Based upon these results, it appears that moi significantly influence the outcome of interactions between B. mallei and murine macrophages and that iNOS activity is critical for the clearance of B. mallei from activated RAW 264.7 cells. 相似文献
937.
938.
Effect of imazapic residues on photosynthetic traits and chlorophyll fluorescence of maize seedlings 总被引:1,自引:0,他引:1
W. C. Su L. L. Sun R. H. Wu Y. H. Ma H. L. Wang H. L. Xu Z. L. Yan C. T. Lu 《Photosynthetica》2017,55(2):294-300
The influence of various concentrations of imazapic residues (0–800 μg kg–1) on the growth, chlorophyll content, and photosynthetic characteristics of maize seedlings was studied in a greenhouse pot experiment. Plant height, root length, shoot dry mass, root dry mass, and total dry mass of maize declined with the increase of imazapic residue concentrations. The root/shoot ratio initially decreased and then increased in presence of imazapic, which indicated that the effects of imazapic residues on plant height and root length might differ in maize seedlings. Lowered chlorophyll content and net photosynthetic rate were observed in leaves of maize seedlings in all treatments and indicated a dose-response relationship to imazapic concentrations. Intercellular carbon dioxide concentration, transpiration rate, and stomatal conductance also declined to varying extents, but the chlorophyll a/b ratio increased gradually together with the increase of imazapic residue concentrations. Generally, the maize seedlings were negatively affected by the imazapic residues in soil. Response of root length and biomass to imazapic residues could be the important index for maize variety selection. 相似文献
939.
Wei Hou Guanjun Zhang Zhi Luo Di Li Haoqiang Ruan Benfang Helen Ruan Lin Su Hongtao Xu 《Bioorganic & medicinal chemistry letters》2017,27(24):5382-5386
A diverse natural product-like (NPL) synthetic abietane diterpenoid library containing 86 compounds were obtained and the SARs were studied based on their antibacterial potential. Further in vitro cytotoxic and in silico drug-like properties evaluation showed that the potent antibacterial compound 84 had good drug-like properties and displayed low cytotoxicity toward noncancerous mammalian cells, indicating the study of AA and DHAA might be a good starting point for the search of novel antimicrobial molecules. Future work should be focused on the optimization of their potency and selectivity. 相似文献
940.
Chun-Long Chen Qian Zhang Jun-Hua Yao Jian-Yong Zhang Bei-Sheng Kang Cheng-Yong Su 《Inorganica chimica acta》2008,361(9-10):2934-2940
The one-dimensional (1D) meso polymeric structure {[Cd2(HL)(N3)2(H2O)] · (DMF)3}n 2 has been assembled from a propeller-like chiral mononuclear complex {[Cd(H3L)(H2O)][Cd(H3L)(H2O)2]}(ClO4)4 1 (H3L = tris(5-methyl-2-benzimidazolylmethyl)amine). The assembly process was achieved by the aid of NaN3 which causes N-deprotonation of the 5-methyl-benzimidazole groups and bridges the opposite enantiomers to form 1D meso chain. Both the monomer 1 and polymer 2 have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis and infrared spectroscopy. The ESI-MS of complex 1 has been studied to understand the assembly process. The photoluminescence measurements of the ligand and the complexes show that the ligand-based emission has been significantly enhanced in the monomer while little changed after polymerization. 相似文献