Historicamente, os métodos tradicionais de ensino visualizaram o professor como uma figura de poder sobre o aluno. Mas mudanças de percepção no processo de ensino-aprendizagem têm ocorrido com a introdução das chamadas 'metodologias ativas de aprendizagem'. Essas são metodologias em que o aluno se torna o protagonista central. Suas aplicações permitem o desenvolvimento de novas competências, como a iniciativa, a criatividade, a criticidade reflexiva, a capacidade de autoavaliação e a cooperação para se trabalhar em equipe. O professor atua como orientador, supervisor e facilitador do processo. O presente artigo objetiva ser uma breve introdução ao histórico, fundamentos e classificações das metodologias ativas de aprendizagem.

Polychlorinated biphenyls (PCBs) are a group of environmental contaminants widely reported to cause gonadal toxicity in both humans and animals. This study investigated the amelioratory role of quercetin in PCBs-induced DNA damage in male Wistar rats. Polychlorinated biphenyls were administered intraperitoneally at a dose of 2 mg kg(-1) alone or in combination with quercetin (orally) at 50 mg kg(-1) for 25 days. Quercetin modulation of PCBs-induced gonadal toxicity was evaluated using selected oxidative stress indices, comet assay, measurement of DNA concentration and histology of the testes. Administration of PCBs alone caused a significant (P < 0.05) depletion in the total thiol level in testes of treated rats. Conversely, the levels of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) production were markedly elevated in testes of PCBs-treated rats compared with control. Further, PCBs exposure produced statistically significant increases in DNA tail migration, degraded double-stranded DNA (dsDNA) concentration and histological alterations of testes of the treated rats compared to control. Quercetin cotreatment significantly improved the testicular antioxidant status, decreased DNA fragmentation and restored the testicular histology, thus demonstrating the protective effect of quercetin in PCBs-treated rats.

Mercury (Hg) is widely distributed in the environment and is known to produce several adverse effects in organisms. The aim of the present study was to examine the in vitro antioxidant activity and Hg chelating ability of the hydroalcoholic extract of Psidium guajava leaves (HEPG). In addition, the potential protective effects of HEPG against Hg(II) were evaluated using a yeast model (Saccharomyces cerevisiae). HEPG was found to exert significant antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl scavenger and inhibition of lipid peroxidation induced by Fe(II) assays in a concentration-dependent manner. The extract also exhibited significant Hg(II) chelating activity. In yeast, Hg(II) induced a significant decrease in cell viability. In contrast, HEPG partially prevented the fall in cell viability induced by Hg(II). In conclusion, HEPG exhibited protective effects against Hg(II)-mediated toxicity, which may be related to both antioxidant and Hg(II)-chelating activities.

Muitos estudantes, do Ensino Médio e do nível universitário, encaram a Genética como uma das mais difíceis disciplinas da Biologia. A utilização de metodologias didáticas diversificadas torna-se uma ferramenta promissora para o ensino, complementando o conteúdo teórico e melhorando o processo de ensino-aprendizagem. Um importante método envolve a utilização de jogos didáticos, os quais reúnem em si as funções lúdica e educativa. Entre seus benefícios, a utilização dos jogos didáticos favorece a motivação, o desenvolvimento do raciocínio e a socialização. Este artigo apresenta uma proposta de jogo didático de trilha, intitulado ‘Na Trilha dos Genes’, envolvendo tabuleiro e cartas de perguntas e curiosidades. A proposta é de baixo custo de implementação e visa propiciar aos estudantes uma melhor compreensão dos conteúdos relacionados à disciplina de Genética.

Methylmercury (MeHg) is a ubiquitous and persistent environmental pollutant that induces serious neurotoxic effects. Diphenyl diselenide [(PhSe)], an organoseleno compound, exerts protective effects against MeHg toxicity, although the complete mechanism remains unclear. The aim of this study was to investigate the mechanisms involved in the protective effect of (PhSe) on the toxicity induced by MeHg using wild-type Saccharomyces cerevisiae and mutants with defects in enzymes and proteins of the antioxidant defense system (yap1Δ, ybp1Δ, ctt1Δ, cat1Δ, sod1Δ, sod2Δ, gsh1Δ, gsh2Δ, gtt1Δ, gtt2Δ, gtt3Δ, gpx1Δ, gpx2Δ, trx1Δ, trx2Δ, trx3Δ, and trr2Δ). In the wild-type strain, (PhSe) protected against the growth inhibition, reactive oxygen species production, and decrease in membrane integrity induced by MeHg and restored thiol levels to values indistinguishable from the control. Single deletions of yap1, sod1, sod2, gsh1, gsh2, gpx1, gpx2, trx1, trx2, and trx3 decreased the capacity of (PhSe) to prevent MeHg toxicity in yeast, indicating their involvement in (PhSe) protection. Together, these results suggest a role of (PhSe) in modulating the gene expression of antioxidant enzymes and ABC transporters through the action of the transcription factor YAP1, preventing the oxidative damage caused by MeHg in S. cerevisiae.