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71.
本文用法瑞植物社会学学派的方法,并经主分量分析验证,对元谋干热河谷的植被进行了重点在群丛及其以下单位的系统分类研究。结果得到9个群丛以及各群丛之下的6个亚群丛、3个群丛变型和两个群丛相的一套系统单位。 相似文献
72.
William Kong Lili He Marc Coppola Jianping Guo Nicole N. Esposito Domenico Coppola Jin Q. Cheng 《The Journal of biological chemistry》2010,285(23):17869-17879
Breast cancer is the second leading cause of cancer death in women. Despite improvement in treatment over the past few decades, there is an urgent need for development of targeted therapies. miR-155 (microRNA-155) is frequently up-regulated in breast cancer. In this study, we demonstrate the critical role of miR-155 in regulation of cell survival and chemosensitivity through down-regulation of FOXO3a in breast cancer. Ectopic expression of miR-155 induces cell survival and chemoresistance to multiple agents, whereas knockdown of miR-155 renders cells to apoptosis and enhances chemosensitivity. Further, we identified FOXO3a as a direct target of miR-155. Sustained overexpression of miR-155 resulted in repression of FOXO3a protein without changing mRNA levels, and knockdown of miR-155 increases FOXO3a. Introduction of FOXO3a cDNA lacking the 3′-untranslated region abrogates miR-155-induced cell survival and chemoresistance. Finally, inverse correlation between miR-155 and FOXO3a levels were observed in a panel of breast cancer cell lines and tumors. In conclusion, our study reveals a molecular link between miR-155 and FOXO3a and presents evidence that miR-155 is a critical therapeutic target in breast cancer. 相似文献
73.
Hongchi Yu Yang Shen Jingsi Jin Yingying Zhang Tang Feng 《Cell Adhesion & Migration》2018,12(1):56-68
Hepatocellular carcinoma (HCC) is a subtype of malignant liver cancer with poor prognosis and limited treatment options. It is noteworthy that mechanical forces in tumor microenvironment play a pivotal role in mediating the behaviors and functions of tumor cells. As an instrumental type of mechanical forces in vivo, fluid shear stress (FSS) has been reported having potent physiologic and pathologic effects on cancer progression. However, the time-dependent mechanochemical transduction in HCC induced by FSS remains unclear. In this study, hepatocellular carcinoma HepG2 cells were exposed to 1.4 dyn/cm2 FSS for transient duration (15s and 30s), short duration (5 min, 15 min and 30 min) and long duration (1h, 2h and 4h), respectively. The expression and translocation of Integrins induced FAK-Rho GTPases signaling events were examined. Our results showed that FSS endowed HepG2 cells with higher migration ability via reorganizing cellular F-actin and disrupting intercellular tight junctions. We further demonstrated that FSS regulated the expression and translocation of Integrins and their downstream signaling cascade in time-dependent patterns. The FSS downregulated focal adhesion components (Paxillin, Vinculin and Talin) while upregulated the expression of Rho GTPases (Cdc42, Rac1 and RhoA) in long durations. These results indicated that FSS enhanced tumor cell migration through Integrins-FAK-Rho GTPases signaling pathway in time-dependent manners. Our in vitro findings shed new light on the role of FSS acting in physiologic and pathological processes during tumor progression, which has emerged as a promising clinical strategy for liver carcinoma. 相似文献
74.
75.
Masatoshi Togami Daphne Blazka Jun Hayashi 《In vitro cellular & developmental biology. Plant》1988,24(7):699-704
Summary A serum-free, hormone and attachment factor supplemented culture for rat H4 hepatoma cells was established. In the defined
medium (Dulbecco's Modified Eagle's +Ham's F12+insulin, transferrin, fibronectin liver cell growth factor, and sodium selenite),
H4 cells grew equally well as in 10% fetal bovine serum supplemented medium. H4 cells in either defined or serum-containing
culture conditions produce transferrin but not albumin or alpha-fetoprotein. In this paper we have studied the effect of various
hormones and pressor peptides on the production of angiotensinogen by H4 cells cultured in defined conditions. Only glucocorticoid
hormone had a significant effect on the production of angiotensinogen, whereas other hormones previously reported to exert
their effect on angiotensinogen production had little or no effect.
This work was supported by grant P01 CA37589 from the National Institutes of Health, Bethesda, MD. 相似文献
76.
Nian Zhou Wayne Zeller Jun Zhang Emmanuel Onua Alex S. Kiselyov Jose Ramirez Guðrún Palsdottir Guðrún Halldorsdottir Þorkell Andrésson Mark E. Gurney Jasbir Singh 《Bioorganic & medicinal chemistry letters》2009,19(5):1528-1531
A series of potent and selective EP3 receptor antagonists are described. Utilizing a pharmacophore model developed for the EP3 receptor, a series of 3,4-disubstituted indoles were found to be efficient ligands for this target. These compounds showed high selectivity over IP, FP and other EP receptors. An optimized molecule 7c featured a sound profile and potency in the functional rat and human platelet aggregation assays. 相似文献
77.
78.
The effects of simulated acid rain on the development and reproduction of E. nicholsi, an important natural enemy of many species of pest mites in China, were studied in the laboratory. The life history parameters
of E. nicholsi were investigated after long-term (about 8 generations) exposure to various levels of simulated acid rain (pH 2.0, 3.0, 4.0,
and 5.6). The results showed that the acid rain had negative effects on some basic parameters of the life history of the E. nicholsi population indirectly. The whole development durations with pH 3.0–5.6 treatments were longer and the duration with pH 2.0
treatment was shorter than with deionized water treatments (control). Adult longevity and oviposition duration were notably
shortened, and female fecundity was decreased by an increase in acidity. The net reproductive rate (R
0) of the populations treated with acid rain was less than that of the control populations and gradually decreased with an
increase in acidity; however, the values of the intrinsic rate of increase (r) were not affected significantly by acid rain, and inhibitory effects of acid rain on the population growth of E. nicholsi were not recognized. 相似文献
79.
1. Larval success was compared when one, two, or three egg clutches were laid in kumquat fruits (≈ 10 ml in volume) either successively on the same day or at the rate of one clutch per day. 2. Increased clutch density was associated with a significant decrease in larval survival rate and non‐significant decreases in larval growth rate and pupal mass. 3. Larval and pupal parameters showed significantly larger variance when clutches were laid on successive days than on the same day, suggesting a competitive advantage for older larvae over younger larvae. 4. The results suggest that, in small fruit, reduced fitness due to larval competition may act against possible fitness benefits due to social facilitation among adult females, hence reducing the likelihood of non‐linear population dynamics caused by processes such as the Allee effect. 相似文献
80.