RESUMO
In early female embryos X-chromosome inactivation occurs concomitant with up regulation of the non-coding RNA, Xist, on the future inactive X-chromosome. Up regulation of Xist and coating of the future inactive X is sufficient to induce silencing. Therefore unlocking the mechanisms of X-chromosome inactivation requires thorough understanding of the transcriptional regulators, both activators and repressors, which control Xist. Mouse pluripotent embryonic stem cells, which have two active X chromosomes, provide a tractable ex vivo model system for studying X-chromosome inactivation, since this process is triggered by differentiation signals in these cultured cells. Yet there are significant discrepancies found between ex vivo analyses in mouse embryonic stem cells and in vivo studies of early embryos. In this review we elaborate on potential models of how Xist is up regulated on a single X chromosome in female cells and how ex vivo and in vivo analyses enlighten our understanding of the activators and repressors that control this non-coding RNA gene.
Assuntos
Inativação do Cromossomo X/genética , Animais , Humanos , Modelos Genéticos , Células-Tronco Pluripotentes/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Sequências Reguladoras de Ácido Nucleico/genéticaRESUMO
In addition to developing innovative research programs, life science research faculty at research-intensive institutions are tasked with providing career mentoring and scientific training to new generations of scientists, including postgraduate, graduate, and undergraduate students. In this essay, we argue for a redefinition of mentoring in laboratory research, to thoroughly distinguish three essential roles played by research faculty relative to their trainees: advisor, educator, and supervisor. In particular, we pay attention to the often unacknowledged and misunderstood role of a faculty member as a supervisor and discuss the impact of neglecting supervisory best practices on trainees, on the diversity of the academic pipeline, and on the research enterprise. We also provide actionable frameworks for research mentors who wish to use inclusive supervisory and pedagogical practices in their laboratory. Finally, we call for more research around the supervisory role of research faculty and its impact on trainees, particularly community college students, in order to help broaden the participation of underrepresented students in STEM fields.