Proteomic analysis of the marine diatom Thalassiosira pseudonana upon exposure to benzo(a)pyrene

Abstract Background The polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants ubiquitously distributed. They are generated by incomplete combustion of organic materials such as wood or fossil fuels. Due to their carcinogenic, mutagenic effects and to their wide distribution in the environment, these pollutants pose many concerns to researchers and regulators. In our laboratories we investigated the effect of Benzo(a)pyrene (BaP) exposure in the marine diatom Thalassiosira pseudonana, which has become an important model organism in aquatic toxicology studies. Results In order to investigate the mechanism of action of PAHs, we exposed the diatoms for 24 h to 36.45 µg/L of B(a)P which inhibits the growth by about 30 % and analysed the relative protein expression profile by a quantitative proteomics approach based on iTRAQ labels. The proteomics profile analysis showed that around 10 % of the identified proteins were regulated and one fourth of them confirmed the gene expression changes seen by DNA microarray. Particularly interesting was the down regulation of the Silicon transporter 1 (SIT1), an enzyme that is responsible for the uptake of silica from the media into the cell of diatoms. Regulation of SIT1 upon BaP treatment was also confirmed at the gene expression level. Conclusions The potential use of the regulated proteins found in this study as early indicators of environmental exposure to PAHs is discussed. In particular, SIT1 is considered a promising biomarker and SIT1 expression changes were confirmed also when the diatoms were exposed to field samples, e.g. marine surface sediments contaminated by PAHs.JRC.DDG.H.5-Rural, water and ecosystem resource

First-time Isolation of Flavonoids and Cytotoxic Potential of the Amazonian Shrub Ptychopetalum olacoides Benth

In the present study, three flavonoids, 3-O-methylquercetin (1), 3,4'-O-dimethylquercetin (2) and 3,7-O-dimethylquercetin (3) were isolated and characterized for the first time from a methanol extract obtained from the species Ptychopetalum olacoides. The structures of compounds were identified by spectroscopic methods (1D-, 2D-NMR, MS and UV) and confirmed by comparison with the respective literature data. The cytotoxic effect of crude extract was evaluated in vitro against three human cancer cell lines. The results showed a mild cytotoxic activity (IC50 = 45.16 mu g/mL) against breast cancer (MCF-7). However, crude extract did not exhibit any cytotoxic effect against normal cell human fibroblast (MRC-5).FAPERJCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ Fed Fluminense, Inst Quim, Dept Quim Organ, Campus Valonguinho, BR-24020141 Niteroi, RJ, BrazilUniv Fed Para, Inst Ciencias Biol, BR-66075110 Belem, Para, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, BR-11070100 Santos, SP, BrazilUniv Fed Rural Rio de Janeiro, Dept Quim, BR-23897000 Seropedica, RJ, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, BR-11070100 Santos, SP, BrazilWeb of Scienc

Detection of silver nanoparticles inside marine diatom Thalassiosira pseudonana by electron microscopy and focused ion beam

In the following article an electron/ion microscopy study will be presented which investigates the uptake of silver nanoparticles (AgNPs) by the marine diatom Thalassiosira pseudonana, a primary producer aquatic species. This organism has a characteristic silica exoskeleton that may represent a barrier for the uptake of some chemical pollutants, including nanoparticles (NPs), but that presents a technical challenge when attempting to use electron-microscopy (EM) methods to study NP uptake. Here we present a convenient method to detect the NPs interacting with the diatom cell. It is based on a fixation procedure involving critical point drying which, without prior slicing of the cell, allows its inspection using transmission electron microscopy. Employing a combination of electron and ion microscopy techniques to selectively cut the cell where the NPs were detected, we are able to demonstrate and visualize for the first time the presence of AgNPs inside the cell membrane

General and specified vulnerability to extreme temperatures among older adults

Extreme temperatures pose significant risks to human health and well-being. Older adults are particularly at risk and their susceptibility is a function of vulnerability to general daily life circumstances and to specified events or threats. For the first time, this paper develops a combined general and specified approach to understand the determinants of vulnerability. The findings show that most participants exhibit high levels of heat-related vulnerability, followed by cold-related vulnerability and lastly, general vulnerability. General vulnerability was shown to be primarily shaped by financial, physical and social assets. Whilst, specified vulnerability was found to be mainly shaped by human, physical and placed based assets. Such findings present opportunities to focus on the types of assets that contribute to reducing vulnerability. These findings also suggest that the role assets play in shaping vulnerability must be attended to if we are to fully understand and effectively implement strategies to reduce vulnerability

Loss and Recovery of Mgat3 and GnT-III Mediated E-cadherin N-glycosylation Is a Mechanism Involved in Epithelial-Mesenchymal-Epithelial Transitions

BACKGROUND: N-acetylglucosaminyltransferase-III (GnT-III) is a glycosyltransferase encoded by Mgat3 that catalyzes the addition of β1,4-bisecting-N-acetylglucosamine on N-glycans. GnT-III has been pointed as a metastases suppressor having varying effects on cell adhesion and migration. We have previously described the existence of a functional feedback loop between E-cadherin expression and GnT-III-mediated glycosylation. The effects of GnT-III-mediated glycosylation on E-cadherin expression and cellular phenotype lead us to evaluate Mgat3 and GnT-III-glycosylation role during Epithelial-Mesenchymal-Transition (EMT) and the reverted process, Mesenchymal-Epithelial-Transition (MET). METHODOLOGY/PRINCIPAL FINDINGS: We analyzed the expression profile and genetic mechanism controlling Mgat3 expression as well as GnT-III-mediated glycosylation, in general and specifically on E-cadherin, during EMT/MET. We found that during EMT, Mgat3 expression was dramatically decreased and later recovered when cells returned to an epithelial-like phenotype. We further identified that Mgat3 promoter methylation/demethylation is involved in this expression regulation. The impact of Mgat3 expression variation, along EMT/MET, leads to a variation in the expression levels of the enzymatic product of GnT-III (bisecting GlcNAc structures), and more importantly, to the specific modification of E-cadherin glycosylation with bisecting GlcNAc structures. CONCLUSIONS/SIGNIFICANCE: Altogether, this work identifies for the first time Mgat3 glycogene expression and GnT-III-mediated glycosylation, specifically on E-cadherin, as a novel and major component of the EMT/MET mechanism signature, supporting its role during EMT/MET

Microbiological quality of human milk from a Brazilian milk bank

OBJECTIVE: The objectives of the present study were to determine the prevalence of potentially pathogenic microorganisms that indicate the hygienic and sanitary conditions of human milk samples collected at a Human Milk Bank. METHODS: Three hundred and thirty eight (338) samples of human milk collected from a milk bank in a maternity in the municipality of Goiânia, in the state of Goias, Brazil were submitted to microbiological analysis. The latter were plated on McConkey agar according to the type of bacteria. Among the total number of samples collected, 194 consisted of raw milk and the remaining 144 were pasteurized milk. RESULTS: The presence of Staphylococcus spp., Streptococcus spp., yeasts and molds, and Enterobacteriaceae was verified in the raw milk samples. Staphylococcus aureus were isolated in 10 (5.2%) samples, Staphylococcus epidermidis in 28 (14.4%) samples, Streptococcus spp. in three (1.6%) samples, yeasts and molds in 43 (22.2%) and Enterobacteriaceae in 49 (25.3%) samples. In a hundred and forty four (144) samples which underwent thermal treatment Staphylococcus aureus was detected in five (3.5%) samples, Staphylococcus epidermidis in 15 (10.4%), Staphylococcus lugdenensis in two (1.4%), Streptococcus spp. in four (2.8%), yeasts and molds in 37 (25.7%), and Enterobacteriaceae in nine (6.3%). CONCLUSIONS: Analysis indicated a high degree of contamination in raw human milk, and as for the pasteurized milk, despite elimination of the great majority of potentially pathogenic microorganisms, the percentage of yeasts and molds was higher than in raw milk, demonstrating that a lower degree of initial contamination would be necessary for pasteurization to be an efficient means of microbiological control.OBJETIVO: Determinar a prevalência de microrganismos indicadores e potencialmente patogênicos que indicam as condições higiênico-sanitárias das amostras de leite humano ordenhado coletadas em banco de leite. MÉTODOS: Foram realizadas análises microbiológicas de 338 amostras de leite humano ordenhado, sendo 194 de leite cru e 144, pasteurizado, coletadas em banco de leite humano de um hospital materno infantil de Goiânia, GO. As análises microbiológicas foram realizadas com semeadura em ágar Mc Conkey, de acordo com o tipo de bactéria. RESULTADOS: No leite cru, verificou-se a presença de Staphylococcus spp. Streptococcus spp., bolores e leveduras e Enterobacteriaceae. Observou-se que Staphylococcus aureus esteve presente em 10 (5,2%) amostras, Staphylococcus epidermidis em 28 (14,4%), Streptococcus spp. em três (1,6%), bolores e leveduras em 43 (22,2%) e Enterobacteriaceae em 49 (25,3%). Das 144 amostras de leite humano ordenhado pasteurizado, detectaram-se Staphylococcus aureus em cinco (3,5%), Staphylococcus epidermidis em 15 (10,4%), Staphylococcus lugdenensis em duas (1,4%), Streptococcus spp. em quatro (2,8%), bolores e leveduras em 37 (25,7%) e Enterobacteriaceae em nove (6,3%). CONCLUSÕES: Os resultados mostraram um alto grau de contaminação no leite cru. No leite pasteurizado, apesar da eliminação da grande maioria de microrganismos potencialmente patogênicos, a percentagem de bolores e leveduras excedeu a de leite cru, mostrando a necessidade de obtenção de um leite com carga microbiana inicial mais baixa para que a pasteurização seja eficiente no controle microbiológico

Mycobacterium tuberculosis associated with severe tuberculosis evades cytosolic surveillance systems and modulates IL-1β production

Genetic diversity of Mycobacterium tuberculosis affects immune responses and clinical outcomes of tuberculosis (TB). However, how bacterial diversity orchestrates immune responses to direct distinct TB severities is unknown. Here we study 681 patients with pulmonary TB and show that M. tuberculosis isolates from cases with mild disease consistently induce robust cytokine responses in macrophages across multiple donors. By contrast, bacteria from patients with severe TB do not do so. Secretion of IL-1β is a good surrogate of the differences observed, and thus to classify strains as probable drivers of different TB severities. Furthermore, we demonstrate that M. tuberculosis isolates that induce low levels of IL-1β production can evade macrophage cytosolic surveillance systems, including cGAS and the inflammasome. Isolates exhibiting this evasion strategy carry candidate mutations, generating sigA recognition boxes or affecting components of the ESX-1 secretion system. Therefore, we provide evidence that M. tuberculosis strains manipulate host-pathogen interactions to drive variable TB severities