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1.
Fang Chang An Yan Li-Na Zhao Wei-Hua Wu Zhenbiao Yang 《植物学报(英文版)》2007,49(8):1261-1270
A tip-focused Ca^2+ gradient is tightly coupled to polarized pollen tube growth, and tip-localized influxes of extracellular Ca^2+ are required for this process. However the molecular identity and regulation of the potential Ca^2+ channels remains elusive. The present study has implicated CNGC18 (cyclic nucleotide-gated channel 18) in polarized pollen tube growth, because its overexpression induced wider and shorter pollen tubes. Moreover, CNGC18 overexpression induced depolarization of pollen tube growth was suppressed by lower extracellular calcium ([Ca^2+]ex). CNGC18-yellow fluorescence protein (YFP) was preferentially localized to the apparent post-Golgi vesicles and the plasma membrane (PM) in the apex of pollen tubes. The PM localization was affected by tip-localized ROP1 signaling. Expression of wild type ROP1 or an active form of ROP1 enhanced CNGC18-YFP localization to the apical region of the PM, whereas expression of RopGAP1 (a ROP1 deactivator) blocked the PM localization. These results support a role for PM-Iocalized CNGC18 in the regulation of polarized pollen tube growth through its potential function in the modulation of calcium influxes. 相似文献
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P物质在家兔延髓腹侧面加压区的升压作用及其机制探讨 总被引:3,自引:0,他引:3
在乌拉坦麻醉,三碘季铵酚制动,人工呼吸的家兔上观察到,延髓腹侧面加压区给予P物质使血压呈剂量依赖性升高,但对心率无明显影响。VSMp给予SP受体阻断使BP明显降低并可阻断SP升压效应,VSMp给予酚妥拉明或哌唑嗪预处理使SP升压效应减弱或消失,而给予育亨宾或心得安对SP升压效应无明显影响。VSMp给予SP可使肾交感神经放电显著增加,并伴有BP显著升高;VSMp给予DSP使RSND和BP明显降低并可 相似文献
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The effect of endothelin-1 has been examined on isolated spontaneously beating right atria and electrically driven left atria from diabetic rats and age-matched controls. Diabetes was induced by a single i.v. injection of streptozotocin (65 mg/kg) 4–5 weeks before the experiments. Endothelin-1 (0.01–100 nM) caused concentration-dependent increases in atrial rate and force; the increases were not different between atria from diabetic and control rats. The ability of endothelin-1 to reduce chronotropic and inotropic responses to noradrenaline was also not different between the two groups. Endothelin-1 (10 nM) decreased the chronotropic response to sympathetic nerve stimulation (2 Hz, 10 s) in atria from control rats by 68 ± 5% (n = 8), but this decrease was slightly smaller (45 ± 6%, N = 8) in atria from diabetic rats.
The results provide no evidence to suggest that the diabetic state markedly alters cardiac responses to endothelin-1. 相似文献
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Transformation of Tobacco, Tomato, Potato, and Arabidopsis thaliana Using a Binary Ti Vector System 总被引:16,自引:1,他引:15 下载免费PDF全文
Using a binary tumor-inducing (Ti) plasmid vector system, several plant species were transformed with a kanamycin resistance marker (neomycin phosphotransferase gene). Four Nicotiana species, seven tomato cultivars, two potato cultivars, and Arabidopsis thaliana were transformed by the binary vector transformation method. In this method, various plant organ pieces were co-cultivated with Agrobacterium tumefaciens cells carrying the binary vector, pGA472, and a helper Ti plasmid. We have also demonstrated that a wild type Ti plasmid can be used as a helper to obtain a transformed plant. 相似文献
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In vitro growth and differentiation of human kidney tubular cells on a basement membrane substrate 总被引:4,自引:0,他引:4
An Hang Yang Jeanine Gould-Kostka Terry D. Oberley 《In vitro cellular & developmental biology. Plant》1987,23(1):34-46
Summary Kidney cortical tubular cells, mainly proximal tubular cells, isolated from human kidney and grown either on a basement membrane
substrate in chemically defined medium or on plastic in serum-supplemented medium, had substantial proliferative potential
and could be propagated for more than 10 generations or 8 passages before senescence. Basement membrane produced on a plastic
substrate by the HR-9 endodermal cell line could replace serum supplementation in promoting tubular cell growth. Tubular cells
grown on an HR-9 basement membrane substrate exhibited stable epithelial morphology over an extended period of time; in the
presence of 5% serum they differentiated into organized structures such as hemicysts and cell cords. Cells grown on plastic
failed to differentiate and gradually degenerated. Tubular cells on HR-9 basement membrane were characterized by densely packed
microvilli, abundant rough endoplasmic reticulum and free polysomes, basal cell membrane interdigitations, a well-developed
endocytotic apparatus, and conspicuous junctional complexes—all features of the proximal tubular cell. Compared with cells
on plastic substrate, there were higher levels of the brush border enzymes γ-glutamyl transpeptidase,l-leucine aminopeptidase, and alkaline phosphatase in cells maintained on an HR-9 basement membrane substrate, further supporting
the conclusion that a basement membrane substrate promoted differentiation of tubular cells. These data and morphological
observations indicate that a basement membrane substrate can promote growth and both functional and morphologic differentiation
of human kidney tubular cells.
This work was supported by the Veterans Administration. 相似文献
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