Too Much Charge Weakens Electrostatic Interactions between Charged Liposomes in Low Ionic-Strength Solutions

Abstract

the target sites and formation of a DNA quadruplex. As a result, target sequences are accessible for the next round of priming and DNA amplification proceeds under isothermal conditions. QPA can proceed in either a linear or an exponential amplification mode. Experiments here demonstrate that linear QPA has a potential to be highly specific. We have combined linear QPA with nicking enzymes to reach the level of exponential signal amplification. In our assays we use specifically designed probes that are complementary to both pathogen and QPA template. When the probe is annealed to the pathogen DNA and the nicking site is folded, the enzyme nicks the pathogen strand and creates the 5'-overhang or primer/template complex, which is elongated by polymerase. At this point the nicking enzyme and polymerase initiate QPA template production, which later binds to QPA primers and produces signal. We will discuss thermodynamic and kinetic bases of these multi-step reaction, which can be conducted isothermally between 55 and 65 C. Genome instability is an underlying factor of all cancers. Defects in DNA repair mechanisms contribute significantly to this factor. Recent reports indicate the mechanical properties of cells change as they advance through different stages of neoplastic transformation. The main goal of this study is to investigate how changes in the intracellular environment and changes in DNA repair protein distribution are altered in cells undergoing neoplastic transformation. For this study we have chosen to use human mammary epithelial (HME) cells from the Weinberg line. Lipofection was used to transiently transfect enhanced green fluorescent protein (egfp) fusions to MSH2 mismatch repair proteins. We have measured the localization and diffusion of these fusions using fluorescence recovery after photobleaching (FRAP) and raster image correlation spectroscopy (RICS) on live cells maintained under appropriate environmental conditions. We have tested normal, immortal, and tumorigenic cells in this study. The acquired data was analyzed using custom written Matlab programs as well as commercially available software. Preliminary results show localization of the fusions to the nucleolus in all cell types tested. The surrounding nucleus generally has the weakest localization signal. We have also observed smaller diffusion coefficients in the nucleus of tumorigenic cells compared to normal cells. A nanostructured polystyrene based inorganic-organic composite membrane has been synthesized by sol-gel method under acidic conditions. Investigation on the electrochemical properties showed that higher membrane potential was observed in case of LiCl than other electrolytes used such as NH 4 Cl, KCl and NaCl for the nanocomposite membrane. Effective fixed charge densities were evaluated from the measured potential and were found to follow the order Li þ > NH 4 þ > K þ > Na þ . The permselectivity, ionic mobility ratio and counter-ion transport number of the composite membrane have also been calculated which suggest that the inor...