Enhancement of Single Molecule Raman Scattering using Sprouted Potato Shaped Bimetallic Nanoparticles.

Herein, for the first time, we report the single molecule surface enhanced resonance Raman scattering (SERRS) and surface enhanced Raman scattering (SERS) spectra with high signal to noise ratio (S/N) using plasmon-active substrates fabricated by sprouted potato shaped Au-Ag bimetallic nanoparticles, prepared using a new one-step synthesis method. This particular shape of the nanoparticles has been obtained by fixing the amount of Au and carefully adjusting the amount of Ag. These nanoparticles have been characterized using scanning electron microscopy, extinction spectroscopy, and glancing angle X-ray diffraction. The single molecule sensitivity of SERS substrates has been tested with two different molecular Raman probes. The origin of the electromagnetic enhancement of single molecule Raman scattering in the presence of sprouted shape nanoparticles has been explained using quasi-static theory as well as finite element method (FEM) simulations. Moreover, the role of (i) methods for binding Raman probe molecules to the substrate, (ii) concentration of molecules, and (iii) Au-Ag ratio on the spectra of molecules has been studied in detail.

Antitubercular activity of alpha,omega-diaminoalkanes, H2N(CH2)nNH2.

A series of 11 alpha,omega-diaminoalkanes, (H(2)N(CH(2))(n)NH(2), n=2-12) have been evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Compounds, (H(2)N(CH(2))(n)NH(2), n=9-12), exhibited a very good activities in the range 2.50-3.12 microg/mL, which can be compared with that of the first line drug, ethambutol (3.12 microg/mL). These results and a preliminary QSAR study can be considered an important start point for the rational design of new leads for anti-TB compounds.

Activation of pRL-TK by 12S E1A oncoprotein: drawbacks of using an internal reference reporter in transcription assays.

In transient expression assays for transcription, a vector carrying the experimental reporter is usually co-transfected with a second vector containing a distinct reporter gene as a control. The second reporter is linked to a constitutive promoter driving a low-level transcription that is unresponsive to the experimental trans-acting transcription factors used. The use of dual reporters enables the normalization of the experimental gene transcription with respect to the control reporter transcription. This method is expected to minimize the inherent variability in transfection data caused by changes in cell density and viability, cell lysis, and the recovery of samples at various stages of the experiment. Here, we report that one of the most widely used internal control reporters, the Renilla luciferase plasmid (pRL-TK), is unresponsive to human tumor suppressor protein p53, a potent transcriptional regulator; however, the reporter transcription is enhanced by another well-known transcriptional regulator, the adenoviral 125 EIA oncoprotein, thereby disqualifying pRL-TK as a universal internal control reporter for transcription assays. Our results reveal the necessity of stringent experiments to test the responsiveness of internal control plasmids to transcriptional regulators present in the assay to avoid the misinterpretation of transcriptional analysis data.

Differential regulation of p53-dependent and -independent proliferating cell nuclear antigen gene transcription by 12 S E1A oncoprotein requires CBP.

The tumor suppressor protein p53 and the adenoviral 12 S E1A oncoprotein are both known to elicit their biological effects mainly by regulating the transcription of important cellular genes. The human proliferating cell nuclear antigen (PCNA) gene is a transcriptional target of both p53 and E1A. We have analyzed the effects of p53 and 12 S E1A, separately as well as together, on PCNA gene transcription. Our results showed that whereas both p53 and 12 S E1A separately activated PCNA transcription, 12 S E1A repressed p53-mediated transcriptional activation. Thus, 12 S E1A uses a dual strategy of transcriptional activation and repression to take control of the cellular PCNA gene regulation. The cyclic AMP-response element in the PCNA core promoter, besides being crucial for basal transcription, synergizes with p53 to activate transcription. The cyclic AMP response element-binding protein (CREB)-binding protein (CBP) is an essential component of both the transcriptional activation and repression by E1A. Our data demonstrate for the first time that E1A can modulate CBP function to activate PCNA transcription, while at the same time repressing p53-mediated activation by disrupting CBP interaction with p53, thereby uncoupling PCNA transcription from the regulatory effects of p53.