Browsing by Author "de Almeida, Eduardo Alves"
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- CICTA2021 conference: advances in environmental toxicology in the face of emerging challenges from global contaminationPublication . de Almeida, Eduardo Alves; Bebianno, Maria; Soto, Manuel; de Souza Abessa, Denis ModeloThe increasing levels of environmental pollutants in combination with global climate change has been a matter of great concern due to the negative impacts caused to natural environments. Studies on these topics are important to predict the environmental risks of pollutants, enabling decision-making towards the development of more efficient laws for the protection and preservation of natural environments against contamination by compounds derived from human activity.
- Molecular and cellular effects of temperature in oysters Crassostrea brasiliana exposed to phenanthrenePublication . Lima, Daína; Zacchi, Flávia Lucena; Mattos, Jacó Joaquim; Flores-Nunes, Fabrício; Gomes, Carlos Henrique Araújo de Miranda; de Mello, Álvaro Cavaler Pessoa; Siebert, Marília Nardelli; Piazza, Clei Endrigo; Taniguchi, Satie; Sasaki, Silvio Tarou; Bícego, Márcia Caruso; Bebianno, Maria João; de Almeida, Eduardo Alves; Bainy, Afonso Celso DiasExposure of aquatic organisms to polycyclic aromatic hydrocarbons (PAH), such as phenanthrene (PHE), may increase the production of reactive oxygen species (ROS) and cause changes in the biotransformation systems. In addition, changes in water temperature can cause adverse effects in the organisms. Estuarine species, like the oyster Crassostrea brasiliana, can adapt and tolerate temperature variation. To evaluate the influence of temperature on biological responses of C. brasiliana exposed to PHE, oysters were maintained at three temperatures (18, 24 and 32 °C) for 15 days and co-exposed afterwards to 100 μg.L-1 of PHE for 24 and 96 h. Levels of PHE in the water and oyster tissues were determined, respectively after 24 and 96 h. In addition, thermal stress, biotransformation and oxidative stress-related genes were analyzed in oyster gills, together with the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferases (GST) and levels of lipid peroxidation. Oyster accumulated significant levels of PHE. HSP70-like transcripts were affected by PHE exposure only at 32 °C. Transcript levels of cytochrome P450 isoforms (CYP2-like2 and CYP2AU1) were down-regulated in oysters exposed to PHE for 24 h at 32 °C. GSTΩ-like transcript levels were also down-regulated in the PHE-exposed group at 32 °C. After 96 h, CYP2-like2 transcripts were higher in the PHE exposed groups at 32 °C. Oysters kept at 18 °C showed higher levels of SOD-like transcripts, together with higher GST, GPx and G6PDH activities, associated to lower levels of lipoperoxidation. In general the biological responses evaluated were more affected by temperature, than by co-exposure to PHE.
- Stress responses in Crassostrea gasar exposed to combined effects of acute pH changes and phenanthrenePublication . Lima, Daína; Mattos, Jacó J.; Piazza, Rômi S.; Righetti, Bárbara Pacheco Harrison; Monteiro, Jhonatas S.; Grott, Suelen Cristina; Alves, Thiago Caique; Taniguchi, Satie; Bícego, Márcia Caruso; de Almeida, Eduardo Alves; Bebianno, Maria João; Medeiros, Igor D.; Bainy, Afonso C.D.Ocean acidification is a result of the decrease in the pH of marine water, caused mainly by the increase in CO2 released in the atmosphere and its consequent dissolution in seawater. These changes can be dramatic for marine organisms especially for oysters Crassostrea gasar if other stressors such as xenobiotics are present. The effect of pH changes (6.5, 7.0 and 8.2) was assessed on the transcript levels of biotransformation [cytochromes P450 (CYP2AU1, CYP2-like2) and glutathione S-transferase (GSTΩ-like)] and antioxidant [superoxide dismutase (SOD-like), catalase (CAT-like) and glutathione peroxidase (GPx-like)] genes, as well as enzyme activities [superoxide dismutase, (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferases transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH)] and lipid peroxidation (MDA) in the gills of Crassostrea gasar exposed to 100 μg·L-1 of phenanthrene (PHE) for 24 and 96 h. Likewise, the PHE burdens was evaluated in whole soft tissues of exposed oysters. The accumulation of PHE in oysters was independent of pH. However, acidification promoted a significant decrease in the transcript levels of some protective genes (24 h exposure: CYP2AU1 and GSTΩ-like; 96 h exposure: CAT-like and GPx-like), which was not observed in the presence of PHE. Activities of GST, CAT and SOD enzymes increased in the oysters exposed to PHE at the control pH (8.2), but at a lower pH values, this activation was suppressed, and no changes were observed in the G6PDH activity and MDA levels. Biotransformation genes showed better responses after 24 h, and antioxidant-coding genes after 96 h, along with the activities of antioxidant enzymes (SOD, CAT), probably because biotransformation of PHE increases the generation of reactive oxygen species. The lack of change in MDA levels suggests that antioxidant modulation efficiently prevented oxidative stress. The effect of pH on the responses to PHE exposure should be taken into account before using these and any other genes as potential molecular biomarkers for PHE exposure.