Laccase Affects the Rate of Cryptococcus neoformans Nonlytic Exocytosis from Macrophages.

Nonlytic exocytosis is a process in which previously ingested microbes are expelled from host phagocytes with the concomitant survival of both cell types. This process has been observed in the interaction of Cryptococcus spp. and other fungal cells with phagocytes as distant as mammalian, bird, and fish macrophages and ameboid predators. Despite a great amount of research dedicated to unraveling this process, there are still many questions about its regulation and its final benefits for host or fungal cells. During a study to characterize the virulence attributes of Brazilian clinical isolates of C. neoformans, we observed great variability in their rates of nonlytic exocytosis and noted a correlation between this process and fungal melanin production/laccase activity. Flow cytometry experiments using melanized cells, nonmelanized cells, and lac1Δ mutants revealed that laccase has a role in the process of nonlytic exocytosis that seems to be independent of melanin production. These results identify a role for laccase in virulence, independent of its role in pigment production, that represents a new variable in the regulation of nonlytic exocytosis.IMPORTANCECryptococcus neoformans is a yeast that causes severe disease, primarily in immunosuppressed people. It has many attributes that allow it to survive and cause disease, such as a polysaccharide capsule and the dark pigment melanin produced by the laccase enzyme. Upon infection, the yeast is ingested by cells called macrophages, whose function is to kill them. Instead, these fungal cells can exit from macrophages in a process called nonlytic exocytosis. We know that this process is controlled by both host and fungal factors, only some of which are known. As part of an ongoing study, we observed that C. neoformans isolates that produce melanin faster are more-frequent targets of nonlytic exocytosis. Further experiments showed that this is probably due to higher production of laccase, because fungi lacking this enzyme are nonlytically exocytosed less often. This shows that laccase is an important signal/regulator of nonlytic exocytosis of C. neoformans from macrophages.

Nível de percepção da comunidade escolar sobre educação ambiental em duas escolas públicas do Distrito Federal ­ Brasil / Level of perception of the school community on environmental education in two public schools of the Federal District ­ Brazil

escola tem papel crucial na formação dos cidadãos e no desenvolvimento da cultura de uma sociedade. Em países desenvolvidos a educação é um dos fatores que diferencia estes países dos países em desenvolvimento. A fim de verificar a importância da educação ambiental (EA) no ensino público brasileiro, dois questionários foram aplicados em duas escolas públicas do Distrito Federal/Brasil. O primeiro questionário foi direcionado aos alunos do 1º e 3º ano do ensino mé-dio e continha dez questões, o segundo questionário foi aplicado aos professores dessas mesmas escolas e foi constituído de nove questões. Ao todo, 72 alunos e 20 professores participaram da pesquisa. Em suma, 72% dos alunos conseguiram definir a EA de maneira contextualizada, 100% dos alunos acreditam que a EA deve ser discutida nas disciplinas de Biologia e Geografia e apenas 8% dos alunos correlacionaram a EA com a prevenção de doenças e saúde pública. Quando analisados os resultados dos professores, 100% acreditam que a EA tem correlação com a saúde pública, porém 50% dos professores afirmaram não ter interesse em participar de curso de formação em EA, pois não há correlação com a disciplina ministrada por eles. Os dados obtidos demonstram que a educação ambiental ainda não possui a devida importância em sala de aula, assim é crucial o empenho de todos os atores da sociedade na implementação de uma cultura de proteção e conscientização dos temas amplos da educação ambiental.