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Campinas, Brazil

Lourenco R.F.,University of Sao Paulo | Leme A.F.P.,Mass Spectrometry Laboratory | Oliveira C.C.,University of Sao Paulo
Journal of Proteome Research | Year: 2013

The yeast exosome is a conserved multiprotein complex essential for RNA processing and degradation. The complex is formed by a nine-subunit core that associates with two hydrolytic 3′-5′ exoribonucleases. Although catalytically inert, the assembly of this nine-subunit core seems to be essential for the exosome activity, as mutations in regions that do not directly bind RNA or are not in the active sites of the exonucleases impair the function of the complex. Previously isolated mutations in the exosome core subunit Rrp43p have been shown to negatively affect the function of the complex. With the aim of investigating the effect of these mutations on the complex stability and activity, Rrp43p and its mutant forms were purified by means of the TAP method. Mass spectrometry analyses showed that lower amounts of the exosome subunits are copurified with the mutant Rrp43p proteins. Additionally, by decreasing the stability of the exosome, other nonspecific protein interactions are favored (the data have been deposited to the ProteomeXchange with identifier PXD000580). Exosome copurified with mutant Rrp43p exhibited increased exonuclease activity, suggesting higher dissociation constants for these mutant complexes. Therefore, data reported here indicate that complexes containing a mutant Rrp43p exhibit decreased stability and provide information on additional protein interactions. © 2013 American Chemical Society.

Iuliano L.,Mass Spectrometry Laboratory
Medical Hypotheses | Year: 2010

Statins and other lipid lowering drugs have been repeatedly described to decrease blood levels of minor fat soluble components such as vitamin E (as α-tocopherol). Clinical consequences of this secondary state of deficiency have not been described so far, but recent biochemical and molecular evidence on homeostatic and molecular responses to vitamin E deficiency in skeletal muscle cells may suggest the hypothesis presented in this paper of a role as risk factor in the development of statin-associated myopathy. This hypothesis that needs to be further investigated, could suggest the need for precautionary measures during lipid lowering therapy, which include timely diagnosis and active prevention of vitamin E deficiency. © 2009 Elsevier Ltd. All rights reserved.

Cavalcanti I.M.G.,University of Campinas | Ricomini Filho A.P.,University of Campinas | Lucena-Ferreira S.C.,University of Campinas | Da Silva W.J.,University of Campinas | And 3 more authors.
Archives of Oral Biology | Year: 2014

Objective The aim of this study was to evaluate the composition of the salivary pellicle (SP) and multispecies biofilm developed on titanium nitrided by cold plasma. Methods Titanium discs were allocated into a control group (Ti) and an experimental group (TiN - titanium-nitrided by cold plasma). The disc surface topography was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The chemical composition of the disc surface was determined by X-ray photoelectron spectroscopy (XPS). Stimulated, clarified, and filtered saliva was used to form pellicles on the discs. Proteome analysis of the adsorbed SP proteins was performed by liquid chromatography-mass spectrometry (LC-MS). The surface free energy (SFE) was evaluated before and after SP formation. A multispecies biofilm composed of Actinomyces naeslundii, Streptococcus oralis, Streptococcus mutans, Fusobacterium nucleatum, Veillonella dispar, and Candida albicans was developed on the SP-coated discs. Viable microorganism counts were determined. The biomass and average thickness of biofilms were analyzed by confocal laser-scanning microscopy (CLSM) with COMSTAT software. The biofilm organization was visualized by SEM. Results The surface topography was similar in both groups. The SFE of the TiN group did not differ from that of the Ti group (p > 0.05), although the adsorption of pellicle proteins increased the SFE in both pellicle-coated groups (p < 0.001). Different proteins were identified on the Ti and TiN surfaces. The amount of biofilm was similar for both groups (p = 0.416), but the counts of F. nucleatum and S. oralis were higher in the TiN group (p < 0.001). Similar biofilms were characterized by the COMSTAT data, CLSM images, and SEM images. Conclusion The titanium nitrided by cold plasma exhibited differences in SP composition and multispecies microbial biofilm population compared to the control titanium surface. © 2014 Elsevier Ltd.

Halas S.,Mass Spectrometry Laboratory | Bojar A.-V.,University of Salzburg | Bojar A.-V.,Universalmuseum | Peryt T.M.,Polish Geological Institute National Research Institute
Chemical Geology | Year: 2015

We describe a new geochemical tool that could provide temperatures of ancient basins in which massive evaporites were deposited: the oxygen isotope composition of fine crystalline quartz found in large halite bodies. Such quartz is well preserved from post-depositional alterations and it can be relatively easily separated. For the purpose of this study, five halite samples were selected from four various evaporite basins, spanning in age from the Early Cambrian to the Late Jurassic. The obtained isotope temperatures refer to locations where evaporites were deposited, i.e. in subtropical zones of the Earth, as it may be estimated from continental distribution during Phanerozoic times. Reasonable temperatures are obtained, with an assumption for the δ18O of brines ranging from -1‰ to 0‰ during halite deposition. The assumption of higher δ18O values leads to unrealistic temperatures, higher than the homogenization temperatures of fluid inclusions in halite. © 2015 Elsevier B.V.

"IDAHO FALLS -- Jim Delmore came to the lab he ran at the Idaho National Laboratory on Nov. 13, 1972, to find it roped off from entry because of a plutonium contamination. A chemist had brought a sample of plutonium nitrate into the Mass Spectrometry Laboratory at the Idaho Chemical Processing Plant the day before that was 10,000 times larger than needed, Delmore said, and the plutonium nitrate spread throughout the lab. Internal tests showed the dose to the lungs of the 13 lab staff was small. But it also showed that several of the workers had been previously contaminated and had not been adequately monitored. 'They were very sloppy then,' said Delmore, now 78."

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