Abstract: Aim Paracetamol (PCM), or acetaminophen, is one of the most used drugs for human treatment of pain and fever. Since it has often been found in the aquatic environment, the aim of this study was to investigate the effects of PCM on the reproductive axis of male Rhamdia quelen catfish. Methods Different biomarkers were evaluated in hypothalamus, liver and gonads, as well as the plasma sexual hormone quantification. The fish were exposed to three PCM concentrations: 0.25, 2.5 and 25 µg.L-1 and to a control group (solvent acetone 0.0003%). After 14 days of exposure, fish were anesthetized, for blood sampling and biometrics, and after euthanasia, the tissues were sampled. Plasma was used for 11- keto testosterone and 17β - estradiol quantification. The hypothalamus was collected for brain aromatase (cyp19a1b) gene expression; the liver for the vitellogenin (vtg) gene expression and biochemical biomarkers; and gonad for the biochemical and histological biomarkers analyses. Results No alterations were observed in the hormone’s levels, sexual maturation level or in cyp19a1b and vtg gene expression. In the liver the non-protein thiols concentration increased at 2.5 µg.L-1 of PCM, and the superoxide dismutase (SOD) activity was reduced at 0.25 µg.L-1 of PCM. In gonads, glutathione S-transferase (GST) activity decreased and SOD activity increased at 25 µg.L-1 of PCM, while the glutathione peroxidase (GPx) activity reduced after exposure to both PCM concentrations. Conclusion The results showed that environmental concentrations of PCM can cause alterations in the antioxidant system, mainly in the gonads of R. quelen males. However, without significant change in the hormones levels or in the expression of genes related to the reproduction axis. These alterations occurred at concentrations already found in aquatic environment, including in Brazil.

Resumo: Objetivo O paracetamol (PCM), ou acetaminofeno, é um dos medicamentos mais utilizados no tratamento humano da dor e da febre. Por ser frequentemente encontrado no ambiente aquático, o objetivo deste estudo foi investigar os efeitos do PCM no eixo reprodutivo de machos do bagre Rhamdia quelen. Métodos Diferentes biomarcadores foram avaliados no hipotálamo, fígado e gônadas, bem como a quantificação de hormônios sexuais. Os peixes foram expostos a três concentrações de PCM: 0,25, 2,5 e 25 µg.L-1 e ao grupo controle (solvente acetona 0,0003%) e após 14 dias foram anestesiados para coleta de sangue e biometria, e a eutanásia foi feita para coleta de tecidos. Do sangue foi obtido plasma para quantificação de 11- keto testosterona e 17β - estradiol. O hipotálamo foi coletado para a expressão do gene da aromatase cerebral (cyp19a1b); o fígado para a expressão do gene da vitelogenina (vtg) e biomarcadores bioquímicos; e gônadas para os biomarcadores bioquímicos e histológicos. Resultados Não foram observadas alterações nos níveis hormonais, no nível de maturação sexual ou na expressão dos genes cyp19a1b e vtg. No fígado, a concentração de tióis não protéicos aumentou em 2,5 µg.L-1 de PCM, e a atividade da superóxido dismutase (SOD) foi reduzida em 0,25 µg.L-1 de PCM. Nas gônadas, a atividade da glutationa S-transferase (GST) diminuiu e a atividade da SOD aumentou em 25 µg.L-1 de PCM, enquanto a atividade da glutationa peroxidase (GPx) diminuiu após a exposição a ambas as concentrações de PCM. Conclusões Esses resultados mostraram que concentrações ambientais de PCM podem causar alterações no sistema antioxidante, principalmente nas gônadas de machos de R. quelen, porém sem alterar significativamente os níveis hormonais ou a expressão de genes relacionados ao eixo reprodutivo. Essas alterações podem ocorrer em concentrações já encontradas em ambientes aquáticos, inclusive no Brasil.

ABSTRACT Changes in physiology of the nervous system and metabolism can be detected through the activity of acetylcholinesterase (AChE), alpha esterase (EST-a) and beta esterase (EST-ß) in chironomids exposed to pollutants. However, to understand the real effect of xenobiotics on organisms, it is important to investigate how certain factors can interfere with enzyme activity. We investigated the effects of different temperatures, food stress and two steps of the enzymatic protocol on the activity of AChE, EST-a and EST-ß in Chironomus sancticaroli. In experiment of thermal stress individuals from the egg stage to the fourth larval instar were exposed to different temperatures (20, 25 and 30 °C). In food stress experiment, larvae were reared until IV instar in a standard setting (25 °C and 0.9 g weekly ration), but from fourth instar on they were divided into groups and offered different feeding regimes (24, 48 and 72 h with/without food). In sample freezing experiment, a group of samples was processed immediately after homogenization and another after freezing for 30 days. To test the effect of centrifugation on samples, enzyme activity was quantified from centrifuged and non-centrifuged samples. The activity of each enzyme reached an optimum at a different temperature. The absence of food triggered different changes in enzyme activity depending on the period of starvation. Freezing and centrifugation of the samples significantly reduced the activity of three enzymes. Based on these results we conclude that the four factors studied had an influence on AChE, EST-a and EST-ß and this influence should be considered in ecotoxicological approaches.

Resumo: A formação inicial de professores inclui o estágio em docência, que proporciona a vivência do cotidiano escolar. A partir disso, o presente estudo investiga a experiência de quatro estagiários de professores de Biologia em diferentes turmas de Ensino Médio da Educação Básica. Para tanto, cada estagiário produziu relatos que foram submetidos à análise da ação docente utilizando o instrumento Matriz 3x3 baseado no sistema didático de Chevallard e na gestão das relações com o saber de Charlot, proposto por Arruda, Lima e Passos. O estágio foi marcado pelo uso de diferentes práticas metodológicas, tais como criação e montagem de modelos didáticos, vídeos e gravuras, de forma que os estagiários puderam refletir sobre a prática docente e sobre as relações existentes no âmbito da escola.

Abstract: Initial training in teaching includes traineeship, providing future teachers the experience of everyday school life. From this, the present study investigates the experience of four biology teacher trainees in different high school classes. Each trainee has produced reports that were submitted to analyze their teaching activities using the 3x3 Matrix instrument based on Chevallard's didactic system and in the relationships with knowledge management of Charlot, which was proposed by Arruda, Lima and Passos. The teaching practice was marked by the use of different methodological practices, such as creating and mounting didactic models, videos and pictures. Thus, the trainees were able to reflect on the teaching practice and on the relationships within the school.

ABSTRACTChironomidae immature are used as bioindicators of sediment quality in aquatic ecosystems and ecotoxicological assays. Histological descriptions for this family are outdated and limited and there are no studies with Neotropical species. The aim of this study was to describe the tissue architecture of several organs of the larva of Chironomus sancticaroli. For the description of the histological pattern, the larvae were fixed in Duboscq solution for insects at 56 °C, followed by routine histologic processing, infiltration in paraffin, and the sections were stained with Hematoxylin–Eosin. After examining the slides, the tube digestive, salivary gland, excretory, nervous, endocrine, circulatory, and integumentary systems and fat body were histologically characterized. The histology allows evaluation of cell morphology, and for being not expensive and easily accessible can be routinely used in biomonitoring. In addition, is a useful tool in ecotoxicological assays and allow to evaluate biomarkers at tissue and cell levels.

Low malathion concentrations influence metabolism in Chironomus sancticaroli (Diptera, Chironomidae) in acute and chronic toxicity tests. Organophosphate compounds are used in agro-systems, and in programs to control pathogen vectors. Because they are continuously applied, organophosphates often reach water sources and may have an impact on aquatic life. The effects of acute and chronic exposure to the organophosphate insecticide malathion on the midge Chironomus sancticaroli are evaluated. To that end, three biochemical biomarkers, acetylcholinesterase (AChE), alpha (EST-α) and beta (EST-β) esterase were used. Acute bioassays with five concentrations of malathion, and chronic bioassays with two concentrations of malathion were carried out. In the acute exposure test, AChE, EST-α and EST-β activities declined by 66, 40 and 37%, respectively, at 0.251 µg L-1 and more than 80% at 1.37, 1.96 and 2.51 µg L-1. In chronic exposure tests, AChE and EST-α activities declined by 28 and 15% at 0.251 µg L-1. Results of the present study show that low concentrations of malathion can influence larval metabolism, indicating high toxicity for Chironomus sancticaroli and environmental risk associated with the use of organophosphates.