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1.
The kinetics of inhibition by protein- and RNA-synthesis inhibitors (cycloheximide and cordycepin, respectively) of indole-3-acetic acid (IAA)-induced elongation growth were investigated using abraded coleoptile segments of Zea mays L. Removal of the cuticle — a diffusion barrier for solutes — by mechanical abrasion of the outer epidermal cell wall increased the effectiveness of inhibitors tremendously. In an attempt to elucidate the role of growth-limiting protein(s) (GLP) in the growth mechanism the following results were obtained. The elongation induced by IAA was completely inhibited when cycloheximide (10 mol·l-1) was applied to abraded coleoptile segments as shortly as 10 min before the onset of the growth response (=5 min after administration of IAA). However, when cycloheximide was applied after 60 min of IAA treatment (when a steady-state growth rate is reached), the time required for complete cessation of growth was much longer (about 40 min). Cycloheximide inhibited the incorporation of [3H]leucine into protein within about 5 min. Cordycepin (400 mol·l-1) prevented IAA-induced growth when applied as shortly as 25 min before the onset of the growth response (=10 min before administration of IAA) but required more than 60 min for a full inhibition of steady-state growth. The incorporation of [3H]adenosine into RNA was inhibited by cordycepin within 10 min. It is concluded that, contrary to previous investigations with nonabraded organ segments, the initiation of growth by IAA depends directly on the synthesis of GLP. Moreover, the apparent lifetime of GLP is at least four times longer than the time required by cycloheximide to inhibit the initiation of growth by IAA. This is interpreted to mean that GLP is not present before IAA starts to act but is synthesized as a consequence of IAA action starting a few minutes before the initiation of growth. Interpreting the kinetics of growth inhibition by cordycepin in a similar way, we further conclude that GLP synthesis is mediated by IAA-induced synthesis of the corresponding mRNA which starts about 10 min before the onset of GLP synthesis. Inhibition by cycloheximide and cordycepin of IAA-induced growth cannot be alleviated by acidifying the cell wall to pH 4-5, indicating that these inhibitors do not act on growth via an inhibition of auxin-mediated proton excretion.Abbreviations CHI
cycloheximide
- COR
cordycepin
- GLP
growth-dimiting protein(s)
- IAA
indole-3-acetic acid
- mRNAGLP
mRNA coding for GLP 相似文献
2.
Rolf Eiben 《Development genes and evolution》1982,191(4):270-276
Summary The formation of tentacles and stolons during metamorphosis is severely disturbed if inhibitors of mRNA metabolism are applied during certain phases of development. The periods of sensitivity to -amanitin are late gastrulation and the disk stage of metamorphosis. A cordycepin sensitive phase exists during the first hour of metamorphosis. In all drug sensitive phases an enhanced poly(A) synthesis is found indicating increased mRNA metabolism in these stages. Pulse-chase experiments show that planula larvae store a poly(A)-rich RNA population sedimenting between 28–18s. These long living molecules are of embryonic origin, are located in RNP particles and are degraded during metamorphosis. The particles in question appear to be stored mainly in interstitial cells. In early metamorphosis no uridine is incorporated but labelled poly(A) is added to preexisting molecules. 相似文献
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柱霉属一新种——蝙蝠蛾柱霉 总被引:5,自引:0,他引:5
从青海省化隆地区采集冬虫夏草新鲜标本,经分离培养获一纯种,并经鉴定是隶属暗色孢科Dematiaceae的柱霉属Scytalidium Pesante,其形态特征与近似种——黄棕柱霉Scytalidium fulvum进行了比较,由于分生孢子量度及生活习性与黄棕柱霉有着明显差别,故定为一新种,命名为蝙蝠蛾柱霉Scytalidium hepiali C.L.Li sp.nov.该新种在PDA培养基上生长迅速,25℃,培养10天菌落直径2.5cm。菌丝相互平排列成菌丝束。产孢细胞裂殖产孢,节孢子2型:(1)无色,透明,薄壁,圆柱形,桶形。(2)淡褐色,厚壁,椭圆形,桶形,亚球形。蝙蝠蛾柱霉在蛋白胨、葡萄糖液体培养基中进行深层培养,26℃,20天。发酵液用乙醇抽提,减压蒸馏,甲醇溶解,过滤,减压浓缩,蒸馏水溶解,冷冻干燥。从1升发酵液中获虫草菌素制品50~70mg。从拮抗试验表明虫草菌素能抑制枯草芽孢杆菌的生长。 相似文献
5.
《Bioorganic & medicinal chemistry》2014,22(21):6174-6182
Upon reacting 3′,4′-unsaturated cytosine (8 and 9) and adenine nucleosides (13 and 14) with XeF2/BF3·OEt2, the respective novel 3′,4′-difluoro-3′-deoxyribofuranosyl nucleosides (10–12 and 15–18) could be obtained. Formation of anti-adducts (11, 16 and 18) revealed that the fluorination involved oxonium ions as incipient intermediates. TBDMS-protected 3′,4′-unsaturated adenosine provided the β-face adducts as sole stereoisomers whereas α-face-selectivity was observed with the TBDPS-protected adenosine 14. The evaluation of the novel 3′-deoxy-3′,4′-difluororibofuranosylcytosine-(19–21) and adenine nucleosides (22–25) against antitumor and antiviral activities revealed that 3′,4′-difluorocordycepin (24) was found to possess anti-HCV activity. The SI of 24 was comparable to that of the anti-HCV drug ribavirin. However, sofosbuvir, FDA-approved novel anti-HCV drug, showed better SI value. Our finding revealed that the introduction of the fluoro-substituent into the 4′-position of cordycepin derivatives decreased the cytotoxicity to the host cell with retention of the antiviral activity. 相似文献
6.
Se-Jung Lee Si-Kwan Kim Wun-Jae Kim Sung-Kwon Moon 《Archives of biochemistry and biophysics》2009,490(2):103-109
Cordycepin (3′-deoxyadenosine), a bioactive compound of Cordycepsmilitaris, has many pharmacological activities. The present study reveals novel molecular mechanisms for the anti-tumor effects of cordycepin in two different bladder cancer cell lines, 5637 and T-24 cells. Cordycepin treatment, at a dose of 200 μM (IC50) during cell-cycle progression resulted in significant and dose-dependent growth inhibition, which was largely due to G2/M-phase arrest, and resulted in an up-regulation of p21WAF1 expression, independent of the p53 pathway. Moreover, treatment with cordycepin-induced phosphorylation of JNK (c-Jun N-terminal kinases). Blockade of JNK function using SP6001259 (JNK-specific inhibitor) and small interfering RNA (si-JNK1) rescued cordycepin-dependent p21WAF1 expression, inhibited cell growth, and decreased cell cycle proteins. These results suggest that cordycepin could be an effective treatment for bladder cancer. 相似文献
7.
采用大孔吸附树脂分离纯化人工蛹虫草培养基残基中的虫草素,以HPLC法测定样品中虫草素含量,筛选出了适宜的大孔树脂NKA-II。研究了pH、洗脱剂乙醇体积分数等因素对该树脂吸附性能及解析性能的影响。结果表明,NKA-II型树脂纯化虫草素的最佳吸附条件为pH9,吸附流速2BV/h,该树脂对虫草素的吸附量可达到16.5mg/g。洗脱工艺条件为2.5倍树脂柱体积的50%乙醇,NKA-II大孔树脂对虫草素的解析率可达到95%以上。 相似文献
8.
Ye Jin Xue Meng Zhidong Qiu Yanping Su Peng Yu Peng Qu 《Saudi Journal of Biological Sciences》2018,25(5):991-995
Public interest in complementary and alternative medicine has been increased worldwide, due to its wide applications in cancer prevention and treatment. Cordycepin is one of the most common and crucial types of complementary and alternative medicine. Cordycepin (3′-deoxyadenosine), a derivative of adenosine, was first isolated from medicine drug Cordyceps militaris. Cordycepin has been widely used as one compound for antitumor, which has been found to exert antiangiogenic, anti-metastatic, and antiproliferative effects, as well as inducing apoptosis. However, the mechanism of its anti-tumor activity is not well known. This review will clarify anti-tumor mechanisms of Cordycepin, which regulate signaling pathways related with tumor growth and metastasis. Cordycepin inhibit tumor growth via upregulating tumor apoptosis, inducing cell cycle arrest and targeting cancer stem cells (CSCs). Cordycepin regulates tumor microenvironment via suppressing tumor metastasis-related pathways. Thus, Cordycepins may be one of important supplement or substitute medicine drug for cancer treatment. 相似文献
9.
【背景】粉被虫草是民间常用药用真菌,具有抗辐射等多种药理作用,虫草素是其重要的活性物质。【目的】探究粉被虫草中提取虫草素的影响因素,为制取虫草素提供参考。【方法】以虫草素得率为指标,用响应面法优化超声提取工艺。分别考察超声时间、液料比和超声功率对提取效率的影响,在单因素实验基础上进行3因素3水平的响应面分析实验。【结果】最优提取条件为超声时间606 s、液料比45.9:1、超声功率400 W,在此条件下虫草素得率为6.136 mg/g,与模型预测值接近,方程拟合良好。【结论】首次对粉被虫草中虫草素的提取条件进行了研究,将对制取虫草素提供参考,有利于粉被虫草的深度开发利用。 相似文献
10.
《Phytomedicine》2014,21(12):1516-1524
Cordyceps militaris is a well-known Chinese traditional medicinal mushroom frequently used for tonics and recently of a potential interest for cancer intervention. Here, we explored the cancer cell killing activity of the hot water extracts of C. militaris cultured mycelia (CMMY) and cultivated fruiting bodies (CMFB). We found that CMFB exhibited a greater cytotoxic effect against various cancer cells over CMMY. Apoptotic phenotypes including apoptotic body formation, DNA laddering, caspase 3 activation and cleavage of PARP proteins were induced by CMFB treatment but only slightly induced by same concentration of CMMY treatment in human HL-60 leukemia cells. Cordycepin in CMFB (10.47 mg/g) is significantly higher (∼15.2 times) than that of CMMY (0.69 mg/g). Using isobolographic analysis, the synergy of cytotoxicity was observed across different combined concentrations of CMMY and cordycepin. By complementing cordycepin into CMMY to the level comparable with CMFB, we observed that CMMY (500 μg/ml) with cordycepin (4.8 μg/ml) induced apoptosis to a level similar to that induced by CMFB (500 μg/ml). Together, our results suggest that cordycepin possesses a synergistic cytotoxic effect with Cordyceps militaris-mediated apoptosis in human leukemia cells and therefore explaining a better anti-proliferating activity of CMFB over CMMY. 相似文献