X-ray dynamical diffraction in amino acid crystals: a step towards improving structural resolution of biological molecules via physical phase measurements

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPIn this work, experimental and data analysis procedures were developed and applied for studying amino acid crystals by means of X-ray phase measurements. The results clearly demonstrated the sensitivity of invariant triplet phases to electronic charge distribution in D-alanine crystals, providing useful information for molecular dynamics studies of intermolecular forces. The feasibility of using phase measurements to investigate radiation damage mechanisms is also discussed on experimental and theoretical grounds.50689700CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP306982/2012-9452031/2015-02012/01367-212/15858-814/08819-114/21284-016/11812-4Acknowledgments are due to the Brazilian funding agencies CNPq (grant Nos. 306982/2012-9 and 452031/20150) and FAPESP (grant Nos. 2012/01367-2, 12/15858-8, 14/08819-1, 14/21284-0 and 16/11812-4), Diamond Light Source (proposal MT11922), and the Brazilian Synchrotron Light Source (proposals 17063, 18011 and 19018). We also thank Professor Lisandro P. Cardoso, Dr Steven Collins and Dr José Brandão-Neto for helpful discussions

Sulforaphane induces oxidative stress and death by p53-independent mechanism: implication of impaired glutathione recycling

Sulforaphane (SFN) is a naturally-occurring isothiocyanate best known for its role as an indirect antioxidant. Notwithstanding, in different cancer cell lines, SFN may promote the accumulation of reactive oxygen species (ROS) and cause cell death e.g. by apoptosis. Osteosarcoma often becomes chemoresistant, and new molecular targets to prevent drug resistance are needed. Here, we aimed to determine the effect of SFN on ROS levels and to identify key biomarkers leading to ROS unbalance and apoptosis in the p53-null MG-63 osteosarcoma cell line. MG-63 cells were exposed to SFN for up to 48 h. At 10 μM concentration or higher, SFN decreased cell viability, increased the%early apoptotic cells and increased caspase 3 activity. At these higher doses, SFN increased ROS levels, which correlated with apoptotic endpoints and cell viability decline. In exposed cells, gene expression analysis revealed only partial induction of phase-2 detoxification genes. More importantly, SFN inhibited ROS-scavenging enzymes and impaired glutathione recycling, as evidenced by inhibition of glutathione reductase (GR) activity and combined inhibition of glutathione peroxidase (GPx) gene expression and enzyme activity. In conclusion, SFN induced oxidative stress and apoptosis via a p53-independent mechanism. GPx expression and activity were found associated with ROS accumulation in MG-63 cells and are potential biomarkers for the efficacy of ROS-inducing agents e.g. as co-adjuvant drugs in osteosarcoma

Exposure to Cr(VI) induces organ dependent MSI in two loci related with photophosphorylation and with glutamine metabolism

Chromium (Cr), as a mutagenic agent in plants, has received less attention than other metal pollutants. To understand if Cr induces microsatellite instability (MSI), Pisum sativum seedlings were exposed for 28 days to different concentrations of Cr(VI) up to 2000mgL-1, and the genetic instability of ten microsatellites (SSRs) was analyzed. In plants exposed to Cr(VI) up to 1000mg L-1, MSI was never observed. However, roots exposed to 2000mgL-1displayed MSI in two of the loci analyzed, corresponding to a mutation rate of 8.3%. SSR2 (inserted in the locus for plastid photosystem I 24kDa light harvesting protein) and SSR6 (inserted in the locus for P. sativum glutamine synthetase) from Cr(VI)-treated roots presented alleles with, respectively, less 6bp and more 3bp than the corresponding controls. This report demonstrates that: (a) SSRs technique is sensitive to detect Cr-induced mutagenicity in plants, being Cr-induced-MSI dose and organ dependent (roots are more sensitive); (b) two Cr-sensitive loci are related with thylakoid photophosphorylation and with glutamine synthetase, respectively; (c) despite MSI is induced by Cr(VI), it only occurs in plants exposed to concentrations higher than 1000mgL-1(values rarely found in real scenarios). Considering these data, we also discuss the known functional changes induced by Cr(VI) in photosynthesis and in glutamine synthetase activity.publishe

High pressure studies on bis(L-histidinate)nickel(II) monohydrate

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFUNCAP - FUNDAÇÃO CEARENSE DE APOIO AO DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICORaman spectra of bis (L-histidinate)nickel(11) monohydrate crystal were obtained for pressures up to 9.5 GPa. Our results show the disappearance of some of the Raman modes and the appearance of other modes. These modifications evidence that the sample undergoes phase transitions at around 0.8 and 3.2 GPa. The role played by the Ni ions and hydrogen bonds in the dynamics of the phase transitions is discussed. Under decompression, down to atmospheric pressure, the original Raman spectra are recovered, showing that both phase transitions are fully reversible.189258264CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFUNCAP - FUNDAÇÃO CEARENSE DE APOIO AO DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFUNCAP - FUNDAÇÃO CEARENSE DE APOIO AO DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO454941/2014-501/201