Prednisone and prednisolone effects on development, blood, biochemical and histopathological markers of Aquarana catesbeianus tadpoles.

Synthetic glucocorticoids are often found in surface waters and can cause harmful effects to aquatic organisms such as amphibians. In this work we evaluated the effects of the drugs prednisone (PD) and prednisolone (PL) on developmental, molecular, blood, biochemical and histological markers. Aquarana catesbeianus tadpoles were exposed for 16 days to environmentally relevant concentrations of 0, 0.1, 1 and 10 µg/L of both drugs. PD increased the transcript levels of the enzyme deiodinase III (Dio3), the hormones cortisol and T4 and delayed development. Changes in the thyroid gland occurred after tadpoles were exposed to both drugs, with a reduction in the diameter and number of follicles and an increase/or decrease in area. Also, both drugs caused a decrease in lymphocytes (L) and an increase in neutrophils (N), thrombocytes, the N:L ratio and lobed and notched erythrocytes. Increased activity of the enzymes superoxide dismutase, glutathione S-transferase and glucose 6-phosphate dehydrogenase was observed after exposure to PD. Furthermore, both drugs caused an increase in the activity of the enzymes catalase and glutathione peroxidase. However, only PD caused oxidative stress in exposed tadpoles, evidenced by increased levels of malondialdehyde and carbonyl proteins. Both drugs caused an increase in inflammatory infiltrates, blood cells and melanomacrophages in the liver. Our results indicate that PD was more toxic than PL, affecting development and causing oxidative stress.

Influence of temperature on the biomarker responses of bullfrog tadpoles (Lithobates catesbeianus) to 2-hydroxyatrazine exposure.

The influence of temperature (25 and 32 °C) on the biomarker responses of bullfrog tadpoles (Lithobates catesbeianus) to different concentrations of the atrazine metabolite 2-hydroxyatrazine (2-HA, 0, 10, 50 and 200 ng.L-1, 16 days), was evaluated. Temperature affected the activities of superoxide dismutase, glutathione S-transferase and acetylcholinesterase. The activities of catalase, glutathione peroxidase, glucose-6-phosphate dehydrogenase and carboxylesterase presented no alterations. Frequencies of micronuclei and nuclear abnormalities were also not altered. 2-HA decreased SOD activity at 25 °C and caused histopathological changes in the liver and the kidney at both temperatures, with the kidney being more affected by the combination of higher temperature and 2-HA exposure, presenting glomerular shrinkage and an increase in Bowman's space. Our results indicate that at environmentally relevant concentrations, 2-HA can cause changes in biomarker responses as well as in the morphology of liver and kidney in L. catesbeianus tadpoles. Temperature has an important influence on biomarker response and histopathological alterations.

Hepatic and blood alterations in Lithobates catesbeianus tadpoles exposed to sulfamethoxazole and oxytetracycline.

In this study the effects of environmentally realistic concentrations of the antibiotics sulfamethoxazole (SMX) and oxytetracyclyne (OTC) on Lithobates catesbeianus tadpoles were evaluated, through the analyzes of the frequencies of micronucleus and nuclear abnormalities in erythrocytes, alterations in leucocytes, liver histopathology, and changes in hepatic esterase activities and oxidative stress biomarkers. The animals were exposed for 16 days at concentrations of 0 (control), 20, 90 and 460 ng L-1. No significant difference was found in the frequencies of micronucleus and nuclear abnormalities. The two highest concentrations of SMX and all concentrations of OTC caused a significant increase in the number of lymphocytes. A significant decrease in the number of neutrophils compared to the control group was observed for all concentrations tested of both antibiotics. Also, decrease in the activity of glutathione S-transferase and high histopathological severity scores, indicating liver damage, were found in tadpoles exposed to the two highest concentrations of SMX and all concentrations of OTC. The main changes in the liver histopathology were the presence of inflammatory infiltrate, melanomacrophages, vascular congestion, blood cells and eosinophils. Esterase activities were unchanged. Indeed, the two highest concentrations of OTC caused a reduction in the activities of superoxide dismutase and glucose 6-phosphate dehydrogenase, while the highest concentration inhibited the activity of glutathione peroxidase and increased protein carbonyl levels. These results evidences that environmentally realistic concentrations of SMX and OTC in aquatic environments are capable to significantly disrupt tadpoles' physiology, possibly affecting negatively their survival rate in natural environments.

Reproductive ability and level of infestation of the Varroa destructor mite in Apis mellifera apiaries in Blumenau, State of Santa Catarina, Brazil / Habilidade reprodutiva e níveis de infestação do ácaro Varroa destructor em colmeias de Apis mellifera no município de Blumenau, Estado de Santa Catarina, Brasil

Varroa destructor mite causes mortality of Apis mellifera bees throughout the world. Its greatest damage to these colonies has been reported in European countries and North America. The impact of the mite is related to the climate and the bee race on each region in which the plague has been established. Varroa causes little damage to the colonies of africanized honeybees in Brazil and the levels of infestation are relatively small and stable. The reproductive ability of Varroa females was evaluated in pupae of workers of 17-18 days of age, obtained from eight beehives of africanized bees for twelve months. The average number of offspring (deutonymphs, protonymphs and eggs) each Varroa produced was 3.18 ± 0.19. The average total number of deutonymph and protonymph was, respectively, 1.57 ± 0.15 and 1.61 ± 0.14. The levels of infestation demonstrated that the plague continue reaching low levels, the average was 4.11 ± 3.42.

O ácaro Varroa destructor é causador da mortalidade de abelhas Apis mellifera em várias partes do mundo. Seus principais danos foram relatados nos países da Europa e América do Norte. O impacto desse ácaro está relacionado às condições climáticas e à raça de abelhas em cada região onde a praga se estabeleceu. A Varroa causa poucos danos nas colônias de abelhas africanizadas no Brasil e os níveis de infestação são relativamente baixos e estáveis em crias e adultos. A habilidade reprodutiva das fêmeas do ácaro, foi avaliada em pupas de operárias de 17-18 idade, obtidas de oito colmeias de abelhas africanizadas, durante 12 meses. O numero médio total de descendentes (deutoninfas, protoninfas e ovos) que cada varroa produziu foi de 3.18 ± 0.19. Para o numero médio total de deutoninfas e protoninfas foi, respectivamente, 1.57 ± 0.15 e 1.61 ± 0.14. Os índices de infestação demonstram que a praga continua alcançando baixos níveis; a média foi de 4.11 ± 3.42.