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71.
Yan Yongshan Qian Jin Xi Xiahui 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(5):529-535
Summary Two 30 g/ml BrdU-resistant sublines and two 60 g/ml BrdU-resistant sublines are induced from a Chinese hamster cell line Wg3h (HGPRT–) by one-step and two-step selections, respectively. By inoculating the cells into BrdU-free medium or by adding more BrdU into the culture medium for 26–27 h, it was found that the two BrdU-resistant sublines analysed have very clear sister chromatid differential (SCD) staining patterns. This indicates that some of the nuclear DNA of the BrdU-resistant cells incorporate with BrdU to reach a kinetic balance. Frequencies of sister chromatid exchange (SCE) of the resistant cells are twice to four times as high as those of the Wg3h cells, depending on which BrdU-resistant subline is analysed. The SCE frequencies of the resistant cells also increase with the BrdU concentration in the medium. Analysis of silver-stained nucleolar organizer regions (NORs) indicates that the NOR activity of three out of the four BrdU-resistant sublines is significantly suppressed, i.e., averages of the Ag-NOR number and number of the chromosomes bearing Ag-NORs per cell decrease significantly. The degree of suppression for different BrdU-resistant sublines may be quite different. The suppressed NOR activity of the resistant cells can gradually be restored when the cells are inoculated into BrdU-free medium, but the recovery speed is far lower than that of the Wg3h cells. The suppression of the NOR activity of the BrdU-resistant sublines should be due to BrdU toxicity. 相似文献
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<正> 本文报道以pAT153质粒为载体克隆的adr亚型乙型肝炎病毒(HBV)全基因的限制性内切酶图谱。重组质粒已命名为pHBV-NCl。重组质粒的提取和酶解采用常规方法。限制性内切酶为Bio-Labs公司产品。用Sepharcry S-1000纯化得到的质粒,经电泳鉴定都是完整的超螺旋DNA。经过鉴定其BamHⅠ、XhoⅠ、XbaⅠ、SstⅡ、SphⅠ、BglⅠ、BglⅡ、BstEⅡ、AceⅠ、AvaⅠ、HincⅡ、HpaⅠ等12种酶的21个切口已被定位。其中XhoⅠ、XbaⅠ、SstⅡ、 相似文献
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Hypoxia-induced inhibition of converting enzyme activity: role in vascular regulation 总被引:3,自引:0,他引:3
Jin H.; Oparil S.; Ann H. S.; Yang R.; Jackson R. M. 《Journal of applied physiology》1987,63(3):1012-1018
Systemic and pulmonary vascular reactivity to graded doses of angiotensin I (ANG I), angiotensin II (ANG II), and, as a control, phenylephrine were examined in 14- or 28-day hypoxia-exposed and air control rats. Hypoxic rats exhibited pulmonary hypertension that was reversible on return to room air, but systemic arterial pressure was not altered by hypoxia. Systemic pressor responses to ANG I and ANG II were significantly less in the hypoxic rats than in the control rats at 14 and 28 days but returned to control levels in hypoxic animals that were then returned to room air, demonstrating reversibility of the hypoxia-induced changes in vascular reactivity. Pulmonary pressor responses to ANG I were significantly less at 14 days, whereas responses to ANG II were significantly greater at 28 days, in hypoxic rats than in controls. There were no significant differences in systemic and pulmonary pressor responses to phenylephrine between the hypoxic and air control animals. The altered systemic and pulmonary pressor responsiveness to ANG I and ANG II in hypoxic rats is probably related to mechanisms specific to the renin-angiotensin system, such as inhibition of intrapulmonary angiotensin-converting enzyme activity and down regulation of ANG II receptors in the systemic circulation. Further study is needed to elucidate these mechanisms. 相似文献
76.
The rapid polyphosphoinositide metabolism may be a triggering event for thrombin-mediated stimulation of human platelets 总被引:4,自引:0,他引:4
A Imai S Nakashima Y Nozawa 《Biochemical and biophysical research communications》1983,110(1):108-115
The metabolism of polyphosphoinositides was examined in human platelets activated by thrombin. The addition of thrombin to [3H]glycerol-labeled platelets induced an initial loss and a subsequent increase of the radioactivity in phosphatidylinositol-4,5-bisphosphate (TPI) without any significant change in phosphatidylinositol-4-phosphate (DPI). A marked enhancement of [32P]Pi incorporation into TPI occurred in parallel with an increase in this lipid content, which was accompanied with a conccurent decrease in phosphatidylinositol (PI). The rate of this subsequent increase in TPI was smaller than that observed in [3H]arachidonic acid-labeled platelets, suggesting that formed TPI in activated platelets may contain much greater amount of arachidonate than preexisting TPI in resting platelets. These data indicate that thrombin causes a rapid change in TPI metabolism (initial degradation of preexisting TPI and subsequent production of arachidonate-rich TPI), which might be a primary candidate to modulate thrombin-induced function in human platelets. 相似文献
77.
Effects of pheriylmethanol (PM), 2-phenylethanol (PE) and 3-phenyl-1-propanol(PP) on the conidiation rhythm and on the fatty acid compositionof phospholipids were examined in Neurospora crassa. The periodfor the conidiation rhythm was shortened in proportion to theconcentration used of PE of more than 1 mM. PM at 10 mM andPP at 3 mM, however, did not cause a decrease in the lengthof the period. PE did not affect the temperature compensationof the length of the period or the amplitude of the phase shiftby light. The ratio of linolenic acid to Hnoleic acid decreased in proportionto the concentrations of PE, PM, and PP in all the phospholipidsexamined. The proportion of phosphatidic acid+diphosphatidylglycerolto the total phospholipids also was decreased by these compounds.Period shortening by PE can not be explained by the change inthe phospholipid fatty acid composition. (Received April 18, 1983; Accepted June 22, 1983) 相似文献
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