Reversal of DNA damage induced Topoisomerase 2 DNA–protein crosslinks by Tdp2

Mammalian Tyrosyl-DNA phosphodiesterase 2 (Tdp2) reverses Topoisomerase 2 (Top2) DNA–protein crosslinks triggered by Top2 engagement of DNA damage or poisoning by anticancer drugs. Tdp2 deficiencies are linked to neurological disease and cellular sensitivity to Top2 poisons. Herein, we report X-ray crystal structures of ligand-free Tdp2 and Tdp2-DNA complexes with alkylated and abasic DNA that unveil a dynamic Tdp2 active site lid and deep substrate binding trench well-suited for engaging the diverse DNA damage triggers of abortive Top2 reactions. Modeling of a proposed Tdp2 reaction coordinate, combined with mutagenesis and biochemical studies support a single Mg2+-ion mechanism assisted by a phosphotyrosyl-arginine cation-π interface. We further identify a Tdp2 active site SNP that ablates Tdp2 Mg2+ binding and catalytic activity, impairs Tdp2 mediated NHEJ of tyrosine blocked termini, and renders cells sensitive to the anticancer agent etoposide. Collectively, our results provide a structural mechanism for Tdp2 engagement of heterogeneous DNA damage that causes Top2 poisoning, and indicate that evaluation of Tdp2 status may be an important personalized medicine biomarker informing on individual sensitivities to chemotherapeutic Top2 poisons

Reversal of DNA damage induced Topoisomerase 2 DNA–protein crosslinks by Tdp2

Mammalian Tyrosyl-DNA phosphodiesterase 2 (Tdp2) reverses Topoisomerase 2 (Top2) DNA–protein crosslinks triggered by Top2 engagement of DNA damage or poisoning by anticancer drugs. Tdp2 deficiencies are linked to neurological disease and cellular sensitivity to Top2 poisons. Herein, we report X-ray crystal structures of ligand-free Tdp2 and Tdp2-DNA complexes with alkylated and abasic DNA that unveil a dynamic Tdp2 active site lid and deep substrate binding trench well-suited for engaging the diverse DNA damage triggers of abortive Top2 reactions. Modeling of a proposed Tdp2 reaction coordinate, combined with mutagenesis and biochemical studies support a single Mg(2+)-ion mechanism assisted by a phosphotyrosyl-arginine cation-π interface. We further identify a Tdp2 active site SNP that ablates Tdp2 Mg(2+) binding and catalytic activity, impairs Tdp2 mediated NHEJ of tyrosine blocked termini, and renders cells sensitive to the anticancer agent etoposide. Collectively, our results provide a structural mechanism for Tdp2 engagement of heterogeneous DNA damage that causes Top2 poisoning, and indicate that evaluation of Tdp2 status may be an important personalized medicine biomarker informing on individual sensitivities to chemotherapeutic Top2 poisons

Becoming a Trainer: The Experience of Philippine English Teachers in the Primary Innovations Project

In an era when English has been spreading exponentially (Crystal, 1997; Graddol, 1997, 2006), a development linked to economic expansion and greater access to knowledge, the role of competent teacher trainers is crucial in facilitating teacher development programs (Burns and Richards, 2009) that can enhance expertise among English teachers so that they can respond more fully to the pedagogic demands of global English. However, relatively little is known about the process of becoming a teacher trainer. This chapter reflects on the experience of four skillful English teachers in the Philippines as they learned how to become teacher trainers in the Primary Innovations Project (PIP). First, I shall give an account of PIP against the background of English teacher education in the Philippines, including a profile of the participants of the study — the Primary Trainers of Teachers (PToTs), and an analysis of PIP content and procedures. Then I describe the PToTs’ experiences of becoming trainers, particularly how they accessed their teaching and training skills and what they learned from such experiences, based on a small-scale inquiry I undertook. I conclude by extracting learning points from the reflection on PToTs’ experiences in relation to the dynamics of ELT trainer development processes and by discussing the implications for the development of thinking on professional learning and the training of teacher trainers

A 5V-class Cobalt-free Battery Cathode with High Loading Enabled by Dry Coating

Transitioning toward more sustainable materials and manufacturing methods will be critical to continue supporting the rapidly expanding market for lithium-ion batteries. Meanwhile, energy storage applications are demanding higher power and energy densities than ever before, with aggressive performance targets like fast charging and greatly extended operating ranges and durations. Due to its high operating voltage and cobalt-free chemistry, the spinel-type LiNi0.5Mn1.5O4 (LNMO) cathode material has attracted great interest as one of the few next-generation candidates capable of addressing this combination of challenges. However, severe capacity degradation and poor interphase stability have thus far impeded the practical application of LNMO. In this study, by leveraging a dry electrode coating process, we demonstrate LNMO electrodes with stable full cell operation (up to 68% after 1000 cycles) and ultra-high loading (up to 9.5 mAh/cm2 in half cells). This excellent cycling stability is ascribed to a stable cathode-electrolyte interphase, a highly distributed and interconnected electronic percolation network, and robust mechanical properties. High-quality images collected using plasma focused ion beam scanning electron microscopy (PFIB-SEM) provide additional insight into this behavior, with a complementary 2-D model illustrating how the electronic percolation network in the dry-coated electrodes more efficiently supports homogeneous electrochemical reaction pathways. These results strongly motivate that LNMO as a high voltage cobalt-free cathode chemistry combined with an energy-efficient dry electrode coating process opens the possibility for sustainable electrode manufacturing of cost-effective and high-energy-density cathode materials

Linguistic Issues in Facial Animation

Our goal is to build a system of 3D animation of facial expressions of emotion correlated with the intonation of the voice. Up till now, the existing systems did not take into account the link between these two features. We will look at the rules that control these relations (intonation/emotions and facial expressions/emotions) as well as the coordination of these various modes of expressions. Given an utterance, we consider how the messages (what is new/old information in the given context) transmitted through the choice of accents and their placement, are conveyed through the face. The facial model integrates the action of each muscle or group of muscles as well as the propagation of the muscles' movement. Our first step will be to enumerate and to differentiate facial movements linked to emotions as opposed to those linked to conversation. Then, we will examine what the rules are that drive them and how their different functions interact. Key words: facial animation, emotion, intona..