Integrated biomarker response index to assess toxic effects of environmentally relevant concentrations of paracetamol in a neotropical catfish (Rhamdia quelen).

The nonsteroidal anti-inflammatory drugs (NSAIDs) are amongst the most commonly detected classes of pharmaceuticals in freshwater environments, with paracetamol being the most abundant. The aim of this study was to evaluate the possible toxic effects of environmentally relevant concentrations (0.25, 2.5 and 25 µg.L-1) of paracetamol in Rhamdia quelen fish exposed for 14 days using different biomarkers. The total count of leukocytes and thrombocytes was reduced at the highest concentration. In the gills, all concentrations of paracetamol reduced the glutathione S-transferase (GST) activity and the reduced glutathione (GSH) levels compared to the control group. The activity of catalase (CAT) was not altered and glutathione peroxidase (GPx) activity increased at the highest concentrations. The superoxide dismutase (SOD) activity decreased at 25 µg.L-1 and the LPO levels increased at 2.5 µg.L-1 when compared to the control group. The concentration of ROS was not different among the groups. In the posterior kidney the activities of GST (2.5 µg.L-1), CAT (2.5 µg.L-1 and at 25 µg. L-1) and GPx and GSH levels increased at all concentrations when compared to the control group. The SOD activity and LPO levels did not change. Paracetamol caused genotoxicity in the blood and gills at concentrations of 2.5 µg.L-1 and in the posterior kidney at 2.5 and 25 µg.L-1. An osmoregulatory imbalance in plasma ions and a reduction in the carbonic anhydrase activity in the gills at 0.25 µg.L-1 were observed. Histopathological alterations occurred in the gills of fish exposed to 25 µg.L-1 and in the posterior kidney at 0.25 and 25 µg.L-1 of paracetamol. The integrated biomarker index showed that the stress caused by the concentration of 25 µg.L-1 was the highest one. These results demonstrated toxic effects of paracetamol on the gills and posterior kidneys of fish, compromising their physiological functions and evidencing the need for monitoring the residues of pharmaceuticals released into aquatic environment.

Effects of low concentrations of ibuprofen on freshwater fish Rhamdia quelen.

Ibuprofen is a pharmaceutical drug widely used by the global population and it has been found in aquatic ecosystems in several countries. This study evaluated the effects of ibuprofen in environmental concentrations (0, 0.1, 1 and 10 µg/L) on the freshwaterspecies Rhamdia quelen exposed for 14 days. In the posterior kidney, ibuprofen increased glutathione-S-transferase activity in all groups exposed. Furthermore, increased glutathione peroxidase activity and the levels of reduced glutathione in the group exposed to 10 µg/L. Ibuprofen decreased the carbonic anhydrase activity in the posterior kidney in all exposed groups, and increased the activity in the gills in group exposed to 0.1 µg/L. The levels of plasma magnesium increased in groups exposed to 0.1 and 1 µg/L. In the blood, ibuprofen decreased the white blood cell count in groups exposed to 0.1 e 1.0 µg/L. Therefore, these results indicated that ibuprofen caused nephrotoxicity and demonstrated immunosuppressive effect in Rhamdia quelen.

Production of cellulosic ethanol from cotton processing residues after pretreatment with dilute sodium hydroxide and enzymatic hydrolysis.

In this study, production of cellulosic ethanol from two cotton processing residues was investigated after pretreatment with dilute sodium hydroxide. Pretreatment performance was investigated using a 2(2) factorial design and the highest glucan conversion was achieved at the most severe alkaline conditions (0.4g NaOH g(-1) of dry biomass and 120°C), reaching 51.6% and 38.8% for cotton gin waste (CGW) and cotton gin dust (CGD), respectively. The susceptibility of pretreated substrates to enzymatic hydrolysis was also investigated and the best condition was achieved at the lowest total solids (5wt%) and the highest enzyme loading (85mg of Cellic CTec2 g(-1) of dry substrate). However, the highest concentration of fermentable sugars - 47.8 and 42.5gL(-1) for CGD and CGW, respectively - was obtained at 15wt% total solids using this same enzyme loading. Substrate hydrolysates had no inhibitory effects on the fermenting microorganism.