The effect of strain on water dissociation on reduced rutile TiO2(110) surface.

The effect of external uniaxial strain on water dissociation on a reduced rutile TiO2(110) surface has been theoretically studied using first-principles calculations. We find that when the tensile strain along [11̄0] is applied, the energy barrier of water dissociation substantially decreases with the increase of strain. In particular, water almost automatically dissociates when the strain is larger than 3%. Besides, the water dissociation mechanism changes from indirect to direct dissociation when the compressive strain is larger than 1.3% along [11̄0] or 3% along [001]. The results strongly suggest that it is feasible to engineer the water dissociation on the reduced rutile TiO2(110) surface using external strain.

Exposure to 3G mobile phone signals does not affect the biological features of brain tumor cells.

BACKGROUND: The increase in mobile phone use has generated concerns about possible risks to human health, especially the development of brain tumors. Whether tumor patients should continue to use mobile telephones has remained unclear because of a paucity of information. Herein, we investigated whether electromagnetic fields from mobile phones could alter the biological features of human tumor cells and act as a tumor-promoting agent. METHODS: Human glioblastoma cell lines, U251-MG and U87-MG, were exposed to 1950-MHz time division-synchronous code division multiple access (TD-SCDMA) at a specific absorption rate (maximum SAR = 5.0 W/kg) for 12, 24, and 48 h. Cell morphologies and ultra-structures were observed by microscopy and the rates of apoptosis and cell cycle progression were monitored by flow cytometry. Additionally, cell growth was determined using the CKK-8 assay, and the expression levels of tumor and apoptosis-related genes and proteins were analyzed by real-time PCR and western blotting, respectively. Tumor formation and invasiveness were measured using a tumorigenicity assay in vivo and migration assays in vitro. RESULTS: No significant differences in either biological features or tumor formation ability were observed between unexposed and exposed glioblastoma cells. Our data showed that exposure to 1950-MHz TD-SCDMA electromagnetic fields for up to 48 h did not act as a cytotoxic or tumor-promoting agent to affect the proliferation or gene expression profile of glioblastoma cells. CONCLUSIONS: Our findings implied that exposing brain tumor cells in vitro for up to 48 h to 1950-MHz continuous TD-SCDMA electromagnetic fields did not elicit a general cell stress response.

Exposure to 1950-MHz TD-SCDMA electromagnetic fields affects the apoptosis of astrocytes via caspase-3-dependent pathway.

The usage of mobile phone increases globally. However, there is still a paucity of data about the impact of electromagnetic fields (EMF) on human health. This study investigated whether EMF radiation would alter the biology of glial cells and act as a tumor-promoting agent. We exposed rat astrocytes and C6 glioma cells to 1950-MHz TD-SCDMA for 12, 24 and 48 h respectively, and found that EMF exposure had differential effects on rat astroctyes and C6 glioma cells. A 48 h of exposure damaged the mitochondria and induced significant apoptosis of astrocytes. Moreover, caspase-3, a hallmark of apoptosis, was highlighted in astrocytes after 48 h of EMF exposure, accompanied by a significantly increased expression of bax and reduced level of bcl-2. The tumorigenicity assays demonstrated that astrocytes did not form tumors in both control and exposure groups. In contrast, the unexposed and exposed C6 glioma cells show no significant differences in both biological feature and tumor formation ability. Therefore, our results implied that exposure to the EMF of 1950-MHz TD-SCDMA may not promote the tumor formation, but continuous exposure damaged the mitochondria of astrocytes and induce apoptosis through a caspase-3-dependent pathway with the involvement of bax and bcl-2.

[Detection of O6-methylguanine-DNA methyltransferase promoter methylation in chemotherapy for glioma].

BACKGROUND AND OBJECTIVE: Epigenetic silencing of the DNA repair gene, O6-methylguanine-DNA methyltransferase (MGMT), is associated with the therapeutic response to methylating agents. This study was to assess the value of detecting the promoter methylation of MGMT gene in chemotherapy for glioma. METHODS: Methylation-specific PCR (MSP) was employed to detect MGMT promoter CpG island methylation in 39 samples of glioma taken from surgery. Western blot and immunohistochemistry were used to detect protein expression. MTT were employed to detect the sensitivity of two glioma cell lines to alkylating agents, ACNU and TMZ. The Kaplan-Meier curve was adopted to estimate the overall survival according to the methylation status of the MGMT promoter. RESULTS: Methylation of MGMT promoter CpG island was detectable in 46.2% of glioma tissues, but not in any normal tissues. The expression rate of MGMT protein was 61.5%. The status of MGMT methylation status was association with the protein level of MGMT (P<0.05). The MGMT gene was demethylated in glioma cell line SHG-44 following 5-Aza-CdR treatment; the expression of MGMT protein was restored and the resistance of SHG44 cells to alkylating agents was reversed. The overall survival was higher in patients with methylated MGMT promoter than in those with unmethylated MGMT promoter (P<0.05). CONCLUSIONS: The status of MGMT promoter CpG island methylation is closely correlated to MGMT protein expression and sensitivity of cells to alkylating agents in glioma. Detection of the methylated sequences of MGMT may be used as a predictive factor for the treatment of glioma.

Characterization of the Sesbania rostrata phytochelatin synthase gene: alternative splicing and function of four isoforms.

Phytochelatins (PCs) play an important role in detoxification of heavy metals in plants. PCs are synthesized from glutathione by phytochelatin synthase (PCS), a dipeptidyltransferase. Sesbania rostrata is a tropical legume plant that can tolerate high concentrations of Cd and Zn. In this study, the S. rostrata PCS gene (SrPCS) and cDNAs were isolated and characterized. Southern blot and sequence analysis revealed that a single copy of the SrPCS gene occurs in the S. rostrata genome, and produces four different SrPCS mRNAs and proteins, SrPCS1-SrPCS4, by alternative splicing of the SrPCS pre-mRNA. The SrPCS1 and SrPCS3 proteins conferred Cd tolerance when expressed in yeast cells, whereas the SrPCS2 and SrPCS4 proteins, which lack the catalytic triad and the N-terminal domains, did not. These results suggested that SrPCS1 and SrPCS3 have potential applications in genetic engineering of plants for enhancing heavy metal tolerance and phytoremediation of contaminated soils.

Cloning and characterization of an RNase-related protein gene preferentially expressed in rice stems.

RNase-related proteins (RRPs) are S- and S-like RNase homologs lacking the active site required for RNase activity. Here we describe the cloning and characterization of the rice (Oryza sativa) RRP gene (OsRRP). A single copy of OsRRP occurs in the rice genome. OsRRP contains three introns and an open reading frame encoding 252 amino acids, with the replacement of two histidines involved in the active site of RNase by lysine and tyrosine respectively. OsRRP is preferentially expressed in stems of wild-type rice and is significantly down-regulated in an increased tillering dwarf mutant ext37.