排序方式: 共有73条查询结果,搜索用时 250 毫秒
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Chemical Constituents of the Roots of Vernonia cumingiana Benth. 总被引:1,自引:0,他引:1
Qing-Hua LIU Jing-Quan YUAN Mao-Rong SUO Jun-Shan YANG 《植物学报(英文版)》2005,47(8):1016-1020
To search for new and bioactive constituents from traditional Chinese medicines, a new steroidal saponin, named vernonioside G (1), was isolated from the roots of Vernonia cumingiana Benth. (Compositae). The structure of vernonioside G was elucidated using spectral methods, particularly two-dimensional nuclear magnetic resonance analysis. Together with the new compound, eight known compounds were also isolated and identified from the roots of V. cumingiana, among which, VE-1 (2) and 24-methylenelanost-9(11)- en-3β-ol acetate (3) were assigned NMR data for the first time and compound 3 was obtained as a natural product from a plant for the first time. 相似文献
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Hai-Ying Shen Paula M. Canas Patricia Garcia-Sanz Jing-Quan Lan Detlev Boison Rosario Moratalla Rodrigo A. Cunha Jiang-Fan Chen 《PloS one》2013,8(11)
Adenosine A2A receptors (A2AR) are located postsynaptically in striatopallidal GABAergic neurons, antagonizing dopamine D2 receptor functions, and are also located presynaptically at corticostriatal terminals, facilitating glutamate release. To address the hypothesis that these two A2AR populations differently control the action of psychostimulants, we characterized A2AR modulation of cocaine-induced effects at the level of DARPP-32 phosphorylation at Thr-34 and Thr-75, c-Fos expression, and psychomotor activity using two lines of cell-type selective A2AR knockout (KO) mice with selective A2AR deletion in GABAergic neurons (striatum-A2AR-KO mice), or with A2AR deletion in both striatal GABAergic neurons and projecting cortical glutamatergic neurons (forebrain-A2AR-KO mice). We demonstrated that striatum-A2AR KO mice lacked A2ARs exclusively in striatal GABAergic terminals whereas forebrain-A2AR KO mice lacked A2ARs in both striatal GABAergic and glutamatergic terminals leading to a blunted A2AR-mediated facilitation of synaptosomal glutamate release. The inactivation of A2ARs in GABAergic neurons reduced striatal DARPP-32 phosphorylation at Thr-34 and increased its phosphorylation at Thr-75. Conversely, the additional deletion of corticostriatal glutamatergic A2ARs produced opposite effects on DARPP-32 phosphorylation at Thr-34 and Thr-75. This distinct modulation of DARPP-32 phosphorylation was associated with opposite responses to cocaine-induced striatal c-Fos expression and psychomotor activity in striatum-A2AR KO (enhanced) and forebrain-A2AR KO mice (reduced). Thus, A2ARs in glutamatergic corticostriatal terminals and in GABAergic striatal neurons modulate the action of psychostimulants and DARPP-32 phosphorylation in opposite ways. We conclude that A2ARs in glutamatergic terminals prominently control the action of psychostimulants and define a novel mechanism by which A2ARs fine-tune striatal activity by integrating GABAergic, dopaminergic and glutamatergic signaling. 相似文献
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Yong-Ping Zhang Fei-Fei Jia Xiao-Mei Zhang Yong-Xu Qiao Kai Shi Yan-Hong Zhou Jing-Quan Yu 《Acta Physiologiae Plantarum》2012,34(2):713-720
Suboptimal root zone temperature (14°C) was imposed on chilling-sensitive cucumber (Cucumis sativus L.) and chilling-tolerant figleaf gourd (Cucurbita ficifolia Bouché) plants. Exposure of roots to low temperature for up to 10 days caused a strong growth inhibition in cucumber compared
with figleaf gourd. Physiological analysis showed that generation of reactive oxygen species (ROS) such as hydrogen peroxide
and superoxide anion was significantly induced in cucumber plants as fast as 1 day after low root zone temperature treatment.
In addition to the significant induction of antioxidant superoxide dismutase activity, low root zone temperature also increased
the mitochondrial electron transport allocated to alternative pathway while decreased cytochrome pathway salicylhydroxamic
acid-resistant respiration. However, these defense responses could not compensate for the ROS production, resulting in membrane
lipid peroxidation and loss of root cell viability in the low root zone temperature treated cucumber roots. In contrast, 14°C
root zone temperature had no significant effects on figleaf gourd plant growth, antioxidant enzymes, ROS levels and alternative
respiratory pathway. Hence, difference in ROS metabolism would be associated with the remarkable difference in adaptability
of cucumber and figleaf gourd plants in response to suboptimal root zone temperature condition. 相似文献
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Kai Shi Li-Jun Fu De-Kun Dong Yan-Hong Zhou Jing-Quan Yu 《Plant Physiology and Biochemistry》2008,46(12):1040-1044
Tomato (Solanum lycopersium L.) plants were grown hydroponically to investigate the changes of energy metabolism and adaptive mechanism in response to root restriction. Root restriction resulted in a significant increase in root lipid peroxidation and reduction in leaf net CO2 assimilation rate, which was accompanied by increase of alcohol dehydrogenase (ADH; EC 1.1.1.1) and lactate dehydrogenase (LDH; EC 1.1.1.27) activities. Total, cytochrome pathway, and alternative pathway respirations were all decreased in the roots after 15 days of root restriction treatment. Accompanied with the decrease of ATP content, ratio of invertase/sucrose synthase activity was increased in the restricted roots together with a decrease in glucose content and an increase in fructose content. We concluded that the decreased energy synthesis under root restriction condition was partially compensated by the energy-conserving sucrose synthase pathway of sucrose metabolism. 相似文献
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通过利用稳态光谱技术 ,时间分辨荧光光谱技术对多变鱼腥藻 (A .vari abilis)中藻红蓝蛋白三聚体 (αβ) 3 内能量传递进行了研究 .结果表明 :在藻红蓝蛋白三聚体内 ,单体内α -PVB发色团与β -PCB发色团间的能量传递仍然存在 ,其能量传递时间常数分别为 30和 1 75~ 2 0 0 ps;与单体不同的是在各向异性的时间分辨荧光光谱结果中 ,得到一个 45ps左右的时间传递常数 ,把其归属为PEC三聚体内 β84 -PCB发色团之间的能量传递过程 .同时也证实在PEC三聚体内 ,β84 -PCB发色团与β155 -PCB发色团的激发态能级发生反转 . 相似文献
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Phycobiliproteins (PBPs) are a type of promising sensitizers for photodynamic therapy (PDT). Upon irradiation (λ>500nm) of an oxygen-saturated aqueous solution of phycobiliproteins, particularly, C-phycocyanin (C-PC), allophycocyanin (APC) or R-phycoerythrin (R-PE), the formation of singlet oxygen (1O2) was detected by using imidazole in the presence of p-nitrosodimethylaniline (RNO). The bleaching of RNO caused by the presence of imidazole in our system showed typical concentration dependence with a maximum at about 8mM imidazole, which is in agreement with the formation of 1O2. In addition, the generation of 1O2 was verified further in the presence of D2O and specific singlet oxygen quencher — 1,4-diazabicyclo [2,2,2] octane (DABCO) and sodium azide (NaN3). Our experimental results indicated that APC possesses high ability to generate reactive oxygen species and the relative quantum yields of photogeneration of 1O2 by PBPs are as follows: APC > C-PC > R-PE. 相似文献
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一株产紫杉醇的南方红豆杉内生真菌的分离及分类研究
总被引:8,自引:0,他引:8从生长在湖北的南方红豆杉树皮中韧皮部分离出一批内生真菌,从中获得一株能产紫杉醇的菌株TPF6。对其形态特征的研究以及生理生化特性的测定(b ilog)结果表明,菌株TPF6与链格孢属有很大的相似性;与18SrDNA分析比对表明,菌株TPF6属于链格孢属,并与链格孢属其他种共享95%~99%的保守序列,其中与交链格孢(Alternaria alternata)18S rDNA的保守度高达99%;全细胞脂肪酸分析结果显示,18:2 C IS9、12/18:0 a为TPF6的主要脂肪酸组分,该菌株与链格孢属(Alternaria)相似度最高,SIM值为59.8%。根据分类学研究结果,菌株TPF6属于半知菌门链格孢属,定名为交链格孢(A.alternata)。应用高压液相色谱技术测定结果表明,菌株TPF6发酵液中紫杉醇含量为84.5μg/L。 相似文献