The effect of ultrafine WO3 nanoparticles on the organization of thylakoids enriched in photosystem II and energy transfer in photosystem II complexes

In this work, a new approach to construct self-assembled hybrid systems based on natural PSII-enriched thylakoid membranes (PSII BBY) is demonstrated. Superfine m-WO3 NPs (≈1–2 nm) are introduced into PSII BBY. Transmission electron microscopy (TEM) measurements showed that even the highest concentrations of NPs used did not degrade the PSII BBY membranes. Using atomic force microscopy (AFM), it is shown that the organization of PSII BBY depends strongly on the concentration of NPs applied. This proved that the superfine NPs can easily penetrate the thylakoid membrane and interact with its components. These changes are also related to the modified energy transfer between the external light-harvesting antennas and the PSII reaction center, shown by absorption and fluorescence experiments. The biohybrid system shows stability at pH 6.5, the native operating environment of PSII, so a high rate of O2 evolution is expected. In addition, the light-induced water-splitting process can be further stimulated by the direct interaction of superfine WO3 NPs with the donor and acceptor sides of PSII. The water-splitting activity and stability of this colloidal system are under investigation

Frequency of Aberrant Promoter Methylation of P15(Ink4b) and O-6-Methylguanine-Dna Methyltransferase Genes in B-Cell Non-Hodgkin Lymphoma: a Pilot Study

The methylation status of the target promoter sequences of p15(INK4B) (p15) and O-6-methylguanine-DNA methyltransferase (MGMT) genes was studied by methylation-specific PCR in 10 adult patients with de novo B-cell non-Hodgkin lymphoma (B-NHL). The aberrant hypermethylation of the p15 gene was more frequent (50%) compared to the hypermethylation of the MGMT gene (30%), and was detected in different types of B-NHL in both genes. Hypermethylation of the MGMT gene occurred exclusively in association with the hypermethylation of the p15 gene. All lymphoma patients with hypermethylation of the p15 and/or MGMT genes had a higher clinical stage of the disease (IV - V). We show the association of anemia and/or thrombocytopenia with the hypermethylation of the p15 gene, ascribing the p15 gene as a potential prognostic marker in B-NHL. Comethylation of MGMT with the p15 gene represents a novel finding and presents both genes as candidates for future studies of the hypermethylation profiles of B-NHL

Stimulus-induced modulation of transcriptional bursting in a single mammalian gene

Mammalian genes are often transcribed discontinuously as short bursts of RNA synthesis followed by longer silent periods. However, how these "on" and "off" transitions, together with the burst sizes, are modulated in single cells to increase gene expression upon stimulation is poorly characterized. By combining single-cell time-lapse luminescence imaging with stochastic modeling of the time traces, we quantified the transcriptional responses of the endogenous connective tissue growth factor gene to different physiological stimuli: serum and TGF-beta 1. Both stimuli caused a rapid and acute increase in burst sizes. Whereas TGF-beta 1 showed prolonged transcriptional activation mediated by an increase of transcription rate, serum stimulation resulted in a large and temporally tight first transcriptional burst, followed by a refractory period in the range of hours. Our study thus reveals how different physiological stimuli can trigger kinetically distinct transcriptional responses of the same gene

Structural, morphological and Raman studies of CdS/CdSe sensitized TiO2 nanocrystalline thin films for quantum dot sensitized solar cell applications

Background: It is well known that quantum dot-sensitized solar cells based on nanostructured semiconductor films are considered as a promising alternative to silicon-based solar cells. The aim of this paper is to investigate the structural and morphological properties of CdS/CdSe quantum dot sensitized photoanodes based on nanocrystalline TiO2 thin films considering their performance can reach an efficiency of 2.7%.Methods: TiO2 thin films were prepared on fluorine tin oxide (FTO) glass via the chemical route using commercial Degussa 25 and crystallized at 550°C. Furthermore, a layer of CdS and CdSe nanoparticles was deposited on the titania film by a sequence of successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) methods. After preparation, samples were analyzed using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy for their structural properties and composition. Scanning electron microscopy (SEM) was used to investigate their surface morphology, while energy dispersive X-ray spectrometry (EDS) was used to analyze the sample stoichiometry.Results: The structural properties and morphology of quantum dot sensitized photoanodes revealed that the titania thin films were highly crystalline belonging predominantly in the tetragonalanatase structure, while the CdS/CdS quantum dots were in the cubic phase. Furthermore, scanning electron microscopy (SEM) along with energy dispersive X-Ray mapping EDS showed little contamination.Conclusions: Combined analysis suggests that our preparation route leads to highly crystalline, stoichiometric photoanodes. This plays an important role in the performance of the quantum dot sensitized solar cells

t(5;6;12 ) associated with resistance to imatinib mesylate in chronic myeloid leukemia

A patient with t(9;22)-positive chronic myelogenous leukemia (CML) developed a resistance to therapy with imatinib mesylate (Glivec) which coincided with the appearance of t(5;6;12) in the same cells with t(9;22) [46,XX,t(5;6;12)(q14?;q21?;q23?),t(9;22)(q34;q11)]. She remains in a continuous chronic phase of CML. This is the first reported instance of karyotype evolution temporally associated, and possibly involved, with the induction of resistance to imatinib mesylate but without any signs of evolution of leukemia toward a more anaplastic and aggressive form