Role of Histone Tails in Structural Stability of the Nucleosome

Histone tails play an important role in nucleosome structure and dynamics. Here we investigate the effect of truncation of histone tails H3, H4, H2A and H2B on nucleosome structure with 100 ns all-atom molecular dynamics simulations. Tail domains of H3 and H2B show propensity of -helics formation during the intact nucleosome simulation. On truncation of H4 or H2B tails no structural change occurs in histones. However, H3 or H2A tail truncation results in structural alterations in the histone core domain, and in both the cases the structural change occurs in the H2A3 domain. We also find that the contacts between the histone H2A C terminal docking domain and surrounding residues are destabilized upon H3 tail truncation. The relation between the present observations and corresponding experiments is discussed

Reflections on urban science teacher-student self-efficacy dynamics

This forum article consists of commentaries-authored by Sumi Hagiwara, Maria S. Rivera Maulucci and Lizette Ramos-on the feature article by Virginia Jennings Bolshakova, Carla C. Johnson, and Charlene M. Czerniak. We reflect on a series of questions that take retrospective, introspective, and prospective views of self-efficacy in science education. We review selected studies that explore some of the historical developments and methodological approaches in the literature and examine a teacher-student self-efficacy system model that shows the ways in which teachers\u27 and students\u27 self-efficacy judgments are based upon multiple individual and shared components, such as identity and social interaction within the classroom and school. We close with a call for the design of measures of teacher-student self-efficacy systems, so that we can begin to tailor professional development experiences to the goals and motivations of individual and collective groups of teachers and students in ways that accommodate the unique cultural features of their classrooms and foster student self-efficacy