Investigation of Thermodynamic Properties of Cu(NH3)4SO4.H2O, a Heisenberg Spin Chain Compound

Detailed experimental investigations of thermal and magnetic properties are presented for Cu(NH3)4SO4.H2O, an ideal uniform Heisenberg spin half chain compound. A comparison of these properties with relevant spin models is also presented. The temperature dependent magnetic susceptibility and specific heat data has been compared with the exact solution for uniform Heisenberg chain model derived by means of Bethe ansatz technique. Field dependent isothermal magnetization curves are simulated by Quantum Monte Carlo technique and compared with the corresponding experimental ones. Specific heat as a function of magnetic field (up to 7T) and temperature (down to 2K) is reported. Subsequently, the data are compared with the corresponding theoretical curves for the infinite Heisenberg spin half chain model with J=6K. Moreover, internal energy and entropy are calculated by analyzing the experimental specific heat data. Magnetic field and temperature dependent behavior of entropy and internal energy are in good agreement with the theoretical predictions

Expression of Green Fluorescence Protein (GFP) in Zebrafish Muscle through Injection: A Gene Therapy Model

Expression of the target gene is important for gene therapy. Presently, localized transgenesis is used for gene therapy which can be achieved by a target gene expression. Here, we have reported the plasmid mediated gene therapy to zebrafish model. For this purpose, we have chosen green fluorescent protein (GFP) as a target gene because the expression can be detected easily. GFP was inserted in a plasmid vector, pQE30 to develop the vector pQE30GFP. The plasmid pQE30GFP was constructed form plasmid, pQE30 and pEGFPC2. pQE30GFP injected directly in one group of fish into the muscle where luciferase expression was noted. In another group, after injection electroporation was performed where we have also noted luciferase expression; but, electroporation cause muscle injury to the zebrafish. In our case, the expression was very strong at the site of injection in first group in compare to electroporation group and in both the cases expression was stable more than two weeks

Mechanisms and roles of the RNA-based gene silencing

RNA silencing is a remarkable type of gene regulation. This process has been found to occur in many different organisms such as plants (co-suppression), fungi (quelling), and animals (RNA interference; RNAi). Double-stranded RNA (dsRNA) is a potent trigger in RNA silencing mechanisms operating in a wide range of organisms. This mechanism recognizes dsRNA and processes them into small 21-25nt RNAs (smRNAs). Small RNAs can guide post-transcriptional degradation of complementary messenger RNAs and in plants, transcriptional gene silencing is occurred by methylation of homologous DNA sequences. In plants, it serves as an antiviral defense, and many plant viruses encode suppressors of silencing such as helper component-proteinase of potyviruses (HC-Pro) and the p25 protein encoded by potato virus X (PVX). HC-Pro acts by preventing accumulation of smRNAs that provide specificity determinant for homologous RNA degradation, but p25 viral protein acts by targeting the mobile silencing signal. The encouraging view is that RNA silencing is part of a sophisticated network of interconnected pathways for cellular defense and development and that it may become a powerful tool to manipulate gene expression experimentally