Biomarker Evaluation in Fish After Prolonged Exposure to Nano-TiO2: Influence of Illumination Conditions and Crystal Phase.

In this study, we evaluated the effects of prolonged exposure to two different nano-TiO2 crystal phases under different illumination conditions. Fish (Piaractus mesopotamicus) were exposed for 21 days to 100 mg/L of nano-TiO2 anatase and a mixture of anatase:rutile (80%:20%) under visible light and UV light (UVA and B, 22.47 J/cm2/h). The following oxidative stress biomarkers were mon- itored: concentrations of lipid hydroperoxide (LPO), carbonylated proteins (PCO), and specific activ- ities of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST). Other biomarkers as well as specific activities of acid phosphatase (AP), Na+, K(+)-ATPase and metalloth- ionein levels (MT) were also evaluated. Moreover, micronucleus and comet assays were performed to assess genotoxicity. Our results showed low toxicity of nano-TiO2 to fish and lack of titanium accumulation in muscle tissue. However, it was observed the occurrence of sublethal effects that were influenced by nano-TiO2 crystal phase and illumination condition. Pure anatase caused more oxidative damage without co-exposure to UV, while the mixture anatase:rutile caused more sub- lethal effects when exposure occurred under UV. These findings show that the specific activity of CAT, GST, PCO levels and comet assay are useful as biomarkers of prolonged exposure to nano- TiO2. Overall, our study substantiates the development and implementation of nanoecotoxicological protocols.

Effect of constant temperatures on the biology, life table, and thermal requirements of Aganaspis pelleranoi (Hymenoptera: Figitidae), a parasitoid of Anastrepha fraterculus (Diptera: Tephritidae).

Aganaspis pelleranoi (Brèthes, 1924) (Hymenoptera: Figitidae) is a koinobiont endoparasitoid of larvae of species of the genus Anastrepha and of Ceratitis capitata. It is a candidate for use as a biological control agent, as under field conditions, it may reach a parasitism rate of 62%. The objective of this study was to determine the effect of different constant temperatures on biological parameters of A. pelleranoi when parasitizing the larva of Anastrepha fraterculus (Wiedemann, 1830) (Diptera: Tephritidae), as well as to determine its thermal requirements. The study was conducted in environmental chambers at 18, 20, 22, 25, 28, and 30 ± 1°C; 70 ± 10% relative humidity; and a 12-h photophase. Females maintained at 18 and 20°C produced more progeny than females at other temperatures tested. The longevity of males and females was inversely proportional to temperature, ranging from 49.1 to 3.73 d for females and from 32.1 to 3.8 d for males at temperatures of 18-30°C, respectively. The duration of the biological cycle (egg-to-adult) was influenced by temperature, and ranged from 69.1 d at 18°C to 30 d at 25°C. No preimaginal development of A. pelleranoi occurred at 28 and 30°C. The relationship between temperature and the demographic parameters of A. pelleranoi showed a linear effect over the temperature range of 18-25°C. The lower temperature threshold and thermal constant were 11.69°C and 391.70 degree days, respectively.

Fish exposure to nano-TiO2 under different experimental conditions: methodological aspects for nanoecotoxicology investigations.

The ecotoxicology of nano-TiO2 has been extensively studied in recent years; however, few toxicological investigations have considered the photocatalytic properties of the substance, which can increase its toxicity to aquatic biota. The aim of this work was to evaluate the effects on fish exposed to different nano-TiO2 concentrations and illumination conditions. The interaction of these variables was investigated by observing the survival of the organisms, together with biomarkers of biochemical and genetic alterations. Fish (Piaractus mesopotamicus) were exposed for 96 h to 0, 1, 10, and 100 mg/L of nano-TiO2, under visible light, and visible light with ultraviolet (UV) light (22.47 J/cm(2)/h). The following biomarkers of oxidative stress were monitored in the liver: concentrations of lipid hydroperoxide and carbonylated protein, and specific activities of superoxide dismutase, catalase, and glutathione S-transferase. Other biomarkers of physiological function were also studied: the specific activities of acid phosphatase and Na,K-ATPase were analyzed in the liver and brain, respectively, and the concentration of metallothionein was measured in the gills. In addition, micronucleus and comet assays were performed with blood as genotoxic biomarkers. Nano-TiO2 caused no mortality under any of the conditions tested, but induced sublethal effects that were influenced by illumination condition. Under both illumination conditions tested, exposure to 100 mg/L showed an inhibition of acid phosphatase activity. Under visible light, there was an increase in metallothionein level in fish exposed to 1 mg/L of nano-TiO2. Under UV light, protein carbonylation was reduced in groups exposed to 1 and 10 mg/L, while nucleus alterations in erythrocytes were higher in fish exposed to 10 mg/L. As well as improving the understanding of nano-TiO2 toxicity, the findings demonstrated the importance of considering the experimental conditions in nanoecotoxicological tests. This work provides information for the development of protocols to study substances whose toxicity is affected by illumination conditions.