ZnO nanoparticles alter redox metabolism of Limnoperna fortunei.

Nanoparticles such as zinc oxide nanoparticles (ZnO-NP) that are incorporated in consumer and industrial products have caused concern about their potential ecotoxicological impact when released into the environment. Bivalve mollusks are susceptible targets for nanoparticle toxicity since nanomaterials can enter the cells by endocytosis mechanisms. The aim of this study was to evaluate the influence of ZnO-NP on the redox metabolism in Limnoperna fortunei and the DNA damage after exposure to ZnO-NP. Adult bivalves were incubated with 1-, 10-, and 50-µg mL-1 ZnO-NP for 2, 4, and 24 h. Ionic Zn release, enzymatic and non-enzymatic antioxidant activity, oxidative damage, and DNA damage were evaluated. Oxidative damage to proteins and lipids were observed after 4-h exposure and returned to baseline levels after 24 h. Superoxide dismutase levels decreased after 4-h exposure and increased after 24 h. No significant alteration was observed in the catalase activity or even DNA double-strand cleavage. The dissociation of ZnO may occur after 24 h, releasing ionic zinc (Zn2+) by hydrolysis, which was confirmed by the increase in the ionic Zn concentration following 24-h exposure. In conclusion, ZnO-NP were able to induce oxidative stress in exposed golden mussels. The golden mussel can modulate its own antioxidant defenses in response to oxidative stress and seems to be able to hydrolyze the nanoparticles and consequently, release Zn2+ into the cellular compartment.

Bioaccessibility of bioactive compounds and antioxidant potential of juçara fruits (Euterpe edulis Martius) subjected to in vitro gastrointestinal digestion.

An in vitro method involving simulated gastrointestinal digestion was used to assess the bioaccessibility of fifteen minerals, twenty-two phenolic compounds and the antioxidant capacity in juçara fruit during seven ripening stages. For minerals and phenolics, respectively, initial contents were up to 1325.9 and 22.9mg100g-1, whereas after in vitro digestion, the maximum values were 556.7 and 14.43mg100g-1 (dry matter). Antioxidant capacity, determined by 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH) and ferric reducing antioxidant power (FRAP), after in vitro digestion decreased 51-78% when compared to the crude extract. Bioaccessible fractions of quercetin, protocatechuic and p-coumaric acids presented positive and significant correlation with results of DPPH and FRAP. Furthermore, our study demonstrated that the ripening stages of juçara fruit influenced the bioaccessibility of compounds and antioxidant capacity, which presented higher levels in purple fruits collected 42-69days after the appearance of the red berries on bunches.

Photosynthetic performance of restored and natural mangroves under different environmental constraints.

We hypothesized that the photosynthetic performance of mangrove stands restored by the single planting of mangroves species would be lowered due to residual stressors. The photosynthetic parameters of the vegetation of three planted mangrove stands, each with a different disturbance history, were compared to reference sites and correlated with edaphic environmental variables. A permutational analysis of variance showed significant interaction when the factors were compared, indicating that the photosynthetic parameters of the restoration areas differed from the reference sites. A univariate analysis of variance showed that all the photosynthetic parameters differed between sites and treatments, except for photosynthetic efficiency (αETR). The combination of environmental variables that best explained the variations observed in the photosynthetic performance indicators were Cu, Pb and elevation disruptions. Fluorescence techniques proved efficient in revealing important physiological differences, representing a powerful tool for rapid analysis of the effectiveness of initiatives aimed at restoring coastal environments.

Determination of cadmium in biological samples solubilized with tetramethylammonium hydroxide by electrothermal atomic absorption spectrometry, using ruthenium as permanent modifier.

The feasibility of Ru as a permanent modifier for the determination of Cd in biological samples treated with tetramethylammonium hydroxide (TMAH) by ET AAS was investigated. The tube treatment with Ru was carried out only once and lasted for about 300 atomization cycles. The pyrolysis and atomization temperatures, 750 degrees C and 1300 degrees C, respectively, were chosen from the temperature curves. The sample dissolution procedure was very simple: a sample aliquot was mixed with a small volume of a 25% m/v TMAH solution, the volume was made up to 50 ml and the mixture was kept at 60 degrees C for 1 h. Six certified biological reference materials were analyzed and the obtained Cd concentrations are within the 95% confidence interval of the certified values, proving the accuracy of the proposed procedure for a variety of biological samples. The calibration curve, with correlation coefficient higher than 0.99, was established for a working range up to 10 microg l(-1). The precision was good as demonstrated by relative standard deviations below 3%, except for one sample. The limit of detection (3sigma) was 0.05 microg l(-1) and the characteristic mass was 1.30 pg, obtained in the presence of the Ru modifier.