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Showing 4 results for G3
Volume 10, Issue 2 (7-2019)
Abstract
Luciferase from firefly Photinus pyralis (P .py) is a peroxisomal enzyme that converts a heterocyclic substrate luciferin to an excited state oxyluciferin in the presence of Mg+2-ATP and O2. Excited oxyluciferin with the emission of visible light is changed to its ground state. The combination of rapidity, sensitivity, and convenience has led to the development of a broad range of luminescence applications. In spite of wide ranges applications, firefly luciferase is unstable against changes in chemical and physical conditions, thereby reduce its precision and sensitivity. The most undesirable instability of the luciferase is low thermostability and high susceptibility to proteolytic degradation. According to previous studies, limited proteolysis by trypsin of P .py luciferase indicated six cleavage sites on two accessible regions: 206-220 (Including K206, R213, and R218) and 329-341 (Including K329, R330, and R337) on N-terminal domain. In this study, we used site-directed mutagenesis to introduce one point mutation on the 329-341 accessible regions of P. py luciferase, in order to investigate the role of R330 on the enzyme structure and function which R330 changed to Q. Based on limited proteolysis data, R330Q mutant didn’t significantly change compared to wild type, but this mutation caused several alterations in enzymatic properties including shifting the pH optimum from 7.5 to 8 and increasing the thermal inactivation. Based on the results, it can be concluded that whilst Arg330 is a conserved residue but not effects on trypsinolysis stability.
Volume 13, Issue 1 (4-2013)
Abstract
With globalization getting momentum, capital inflow has been an instrument for economies to grow fast in recent decades. Hence, identifying the factors that affect capital inflow and outflow - net international capital mobility- would be desirable to achieve economic stability. As usual, one of the factors that influence on capital inflow is high return of capital. New experiments explore the crucial role of risk and liquidity intensive on net international capital mobility. So, the purpose of this study is to analyze the analytical impact of credit risk scoring on the net international capital mobility in Iran within the period of 1980-2009. To achieve credit risk scoring, the Fink's scoring model has been used to identify the determinants of credit risk. Then, the rank of each factor has been appeared separately and finally the country's credit risk scoring has been estimated. Then, the final model using time series data and ordinary least squares method are analyzed. The impact of liquidity, different return of inside and outside and credit risk on net international capital mobility in Iran are discussed at the end of the paper. The results show that all mentioned variables have an anticipated effect on net capital inflow.
Volume 17, Issue 3 (10-2014)
Abstract
Objective:Glioblastoma is an invasive tumor of the central nervous system. Epigenetic therapy of cancer is potentially very useful in reversing some of cancer defects due to reversibility of epigenetic alterations. MEG3 is a tumor suppressor long non-coding RNA (lncRNA) that expresses in the majority of normal tissues. Methylation of the MEG3 promoter region elicits a decrease in its expression in glioblastoma cells. Bioactive nutrients including curcumin offer great potential in altering DNA methylation status. Herein, we aim to investigate the epigenetic-based role of dendrosomal-curcumin (DNC) in upregulation of MEG3 expression in glioblastoma cells. Methods: We evaluated DNC entrance to U87MG cells with the use of the fluorescent characteristics of curcumin. Next we performed the MTT assay to evaluate DNC and dendrosome effects on cell viability. The ability of DNC to boost expression of MEG3 in DNA methylation regulation was accomplished by a study of the relative expressions of MEG3 and DNA methylation regulator enzymes, DNA methyltransferases (DNMT1, DNMT3A and 3B) using semi-quantitative and quantitative PCR. Results: We observed the entrance of DNC into U87MG cells. DNC significantly caused U87MG cell death in a time and dose-dependent manner. However dendrosome did not show any toxic effect on this cell line. Data acquired from gene expression assays determined that DNC upregulated MEG3 expression (P<0.05) and downregulated DNMT3B expression (P<0.05). There was no significant effect on DNMT1, 3A expression in U87MG cells. Conclusion: The data showed that DNC could awaken epigenetically silenced tumor suppressor genes through an ambiguous route in glioblastoma cells. Notwithstanding, DNA hypomethylation has occurred by downregulation of DNMTs, inactive DNA demethylation and or active demethylation, subsequently tumor suppressor genes such as MEG3 a cell growth regulator overexpressed. We concluded that DNC has useful characteristics in epigenetic therapy of glioblastoma.
Ebrahim Abbasi Abbasi, Fatemeh Rastegarnia,
Volume 21, Issue 4 (10-2014)
Abstract
The aim of the study is to examine the effect of ownership concentration by sum of major shareholders on the firm value. The sample used for the research included 69 firms listed during the years 2005-2009 in Tehran Stock exchange. The statistical method used for testing the research hypotheses was "Panel Data". To test the relationship between ownership of major stockholders and firm value, multi-linear and nonlinear regression was utilized. The findings are indicative of the existence of a significant and positive linear relationship between ownership concentration of sum of major stockholders and firm value and also of lack of nonlinear relationship between the square sum of ownership by major stockholders and firm value. The results of piecewise test of sum of major stockholders shows that there is no significant relationship between sum of major stockholders and firm value in the break points of 10% and 25% and 50% and 70%.
