PAX3 Confers Functional Heterogeneity in Skeletal Muscle Stem Cell Responses to Environmental Stress

International audienceMuscle satellite cells (MuSCs) are the quiescent muscle stem cells required for adult skeletal muscle repair. The impact of environmental stress such as pollution on MuSC behavior remains unexplored. We evaluated the impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure, a ubiquitous and highly toxic pollutant, on MuSCs by combining in vivo mouse molecular genetic models with ex vivo studies. While all MuSCs express the transcription factor PAX7, we show that a subset also express PAX3 and exhibit resistance to environmental stress. Upon systemic TCDD treatment, PAX3-negative MuSCs display impaired survival, atypical activation, and sporadic differentiation through xenobiotic aryl hydrocarbon receptor signaling. We further show that PAX3-positive MuSCs become sensitized to environmental stress when PAX3 function is impaired and that PAX3-mediated induction of mTORC1 is required for protection. Our study, therefore, identifies a functional heterogeneity of MuSCs in response to environmental stress controlled by PAX3

"Em todos os lares, o conforto moral da ciência e da arte": a Revista Nacional de Educação e a divulgação científica no Brasil (1932-34) "In all homes, the moral comfort of science and of art": the Revista Nacional de Educação and scientific dissemination in Brazil (1932-34)

A Revista Nacional de Educação foi editada, entre 1932 e 1934, pelo Museu Nacional do Rio de Janeiro, sob os auspícios do Ministério da Educação e Saúde Pública e direção de Roquette-Pinto. Seu objetivo principal era a veiculação de conteúdos de ciência, história e arte para um público mais amplo das várias regiões do Brasil. Os artigos são escritos por intelectuais da época, muitos deles atuantes cientistas do Museu Nacional, além de traduções de trechos de alguns viajantes. Cada um de seus números era impresso com custos reduzidos e em expressiva tiragem. Apresentando-se como iniciativa de uma República renovada, parte de uma estratégia mais ampla de inaugurar novas relações entre o governo e uma população a ser educada, a revista se autodefiniu como "um marco espiritual da nacionalidade", sintonizada ao ideal de um Estado cuja ação pedagógica constituísse um povo e uma nação.<br>Between 1932 and 1934, the journal Revista Nacional de Educação was published by Rio de Janeiro's National Museum, under the auspices of the Brazilian Ministry of Education and Public Health and under the direction of Roquette-Pinto. Its main goal was to disseminate information on science, history, and art among a wide-ranging Brazilian public. The articles were written by the intellectuals of the day, many of whom were scientists at the Museu Nacional. The Revista also published translations of excerpts by a number of travelers. Every issue was published at a low cost, with a significant number of copies. The journal was touted as the initiative of a renewed Republic, part of a broader strategy of inaugurating new relations between government and a population to be educated. It defined itself as "a spiritual milestone in the Brazilian nationality" in tune with the ideal of a State whose educational initiatives were meant to constitute a people and a nation