The 2017 RGS-IBG chair’s theme: decolonising geographical knowledges, or reproducing coloniality?

The theme for the chair’s plenaries at the 2017 Royal Geographical Society (RGS) with the Institute of British Geographers (IBG) Annual Conference is ‘Decolonising geographical knowledges: opening geography out to the world’. This commentary explains why this pursuit of critical consciousness via decolonial thinking could do more harm than good. We show how the emphasis on decolonising geographical knowledges rather than structures, institutions and praxis reproduces coloniality, because it recenteres non-Indigenous, white and otherwise privileged groups in the global architecture of knowledge production. It is argued that an effective decolonial movement within geography must recognise the intersectionality of indigeneity and race, and necessitates that the terms on which the discipline starts debates about decolonisation and decoloniality are determined by those racialized as Indigenous and non-white by coloniality

The school food environment and adolescent obesity: qualitative insights from high school principals and food service personnel

<p>Abstract</p> <p>Objectives</p> <p>To examine high school personnel's perceptions of the school environment, its impact on obesity, and the potential impact of legislation regulating schools' food/beverage offerings.</p> <p>Methods</p> <p>Semi-structured interviews were conducted with the principal (n = 8) and dietitian/food service manager (n = 7) at 8 schools (4 rural, 4 suburban) participating in a larger study examining the relationship between the school environment and adolescent health behavior patterns.</p> <p>Results</p> <p>Principal themes included: 1) Obesity is a problem in general, but not at their school, 2) Schools have been unfairly targeted above more salient factors (e.g., community and home environment), 3) Attempts at change should start before high school, 4) Student health is one priority area among multiple competing demands; academic achievement is the top priority, 5) Legislation should be informed by educators and better incorporate the school's perspective. Food service themes included: 1) Obesity is not a problem at their school; school food service is not the cause, 2) Food offerings are based largely on the importance of preparing students for the real world by providing choice and the need to maintain high participation rates; both healthy and unhealthy options are available, 3) A la carte keeps lunch participation high and prices low but should be used as a supplement, not a replacement, to the main meal, 4) Vending provides school's additional revenue; vending is <b>not </b>part of food service and is appropriate if it does not interfere with the lunch program.</p> <p>Conclusion</p> <p>Discrepancies exist between government/public health officials and school personnel that may inhibit collaborative efforts to address obesity through modifications to the school environment. Future policy initiatives may be enhanced by seeking the input of school personnel, providing recommendations firmly grounded in evidence-based practice, framing initiatives in terms of their potential impact on the issues of most concern to schools (e.g., academic achievement, finances/revenue), and minimizing barriers by providing schools adequate resources to carry out and evaluate the effectiveness of their efforts.</p

Telomeric Overhang Length Determines Structural Dynamics and Accessibility to Telomerase and ALT-Associated Proteins

SummaryThe G-rich single-stranded DNA at the 3′ end of human telomeres can self-fold into G-quaduplex (GQ). However, telomere lengthening by telomerase or the recombination-based alternative lengthening of telomere (ALT) mechanism requires protein loading on the overhang. Using single-molecule fluorescence spectroscopy, we discovered that lengthening the telomeric overhang also increased the rate of dynamic exchanges between structural conformations. Overhangs with five to seven TTAGGG repeats, compared with four repeats, showed much greater dynamics and accessibility to telomerase binding and activity and loading of the ALT-associated proteins RAD51, WRN, and BLM. Although the eight repeats are highly dynamic, they can fold into two GQs, which limited protein accessibility. In contrast, the telomere-specific protein POT1 is unique in that it binds independently of repeat number. Our results suggest that the telomeric overhang length and dynamics may contribute to the regulation of telomere extension via telomerase action and the ALT mechanism

Benthic-Pelagic Links and Rocky Intertidal Communities: Bottom-Up Effects on Top-Down Control?

Insight into the dependence of benthic communities on biological and physical processes in nearshore pelagic environments, long considered a ``black box,'' has eluded ecologists. In rocky intertidal communities at Oregon coastal sites 80 km apart, differences in abundance of sessile invertebrates, herbivores, carnivores, and macrophytes in the low zone were not readily explained by local scale differences in hydrodynamic or physical conditions (wave forces, surge flow, or air temperature during low tide). Field experiments employing predator and herbivore manipulations and prey transplants suggested top-down (predation, grazing) processes varied positively with bottom-up processes (growth of filter-feeders, prey recruitment), but the basis for these differences was unknown. Shore-based sampling revealed that between-site differences were associated with nearshore oceanographic conditions, including phytoplankton concentration and productivity, particulates, and water temperature during upwelling. Further, samples taken at 19 sites along 380 km of coastline suggested that the differences documented between two sites reflect broader scale gradients of phytoplankton concentration. Among several alternative explanations, a coastal hydrodynamics hypothesis, reflecting mesoscale (tens to hundreds of kilometers) variation in the interaction between offshore currents and winds and continental shelf bathymetry, was inferred to be the primary underlying cause. Satellite imagery and offshore chlorophyll-a samples are consistent with the postulated mechanism. Our results suggest that benthic community dynamics can be coupled to pelagic ecosystems by both trophic and transport linkages.KEYWORDS: scale, productivity, currents, upwelling, community structureThis is the publisher’s final pdf. The published article is copyrighted by the National Academy of Sciences of the United States of America and can be found at: http://www.pnas.org

A CLK3-HMGA2 Alternative Splicing Axis Impacts Human Hematopoietic Stem Cell Molecular Identity throughout Development

While gene expression dynamics have been extensively cataloged during hematopoietic differentiation in the adult, less is known about transcriptome diversity of human hematopoietic stem cells (HSCs) during development. To characterize transcriptional and post-transcriptional changes in HSCs during development, we leveraged high-throughput genomic approaches to profile miRNAs, lincRNAs, and mRNAs. Our findings indicate that HSCs manifest distinct alternative splicing patterns in key hematopoietic regulators. Detailed analysis of the splicing dynamics and function of one such regulator, HMGA2, identified an alternative isoform that escapes miRNA-mediated targeting. We further identified the splicing kinase CLK3 that, by regulating HMGA2 splicing, preserves HMGA2 function in the setting of an increase in let-7 miRNA levels, delineating how CLK3 and HMGA2 form a functional axis that influences HSC properties during development. Collectively, our study highlights molecular mechanisms by which alternative splicing and miRNA-mediated post-transcriptional regulation impact the molecular identity and stage-specific developmental features of human HSCs. Human hematopoietic stem cells (HSCs) display substantial transcriptional diversity during development. Here, we investigated the contribution of alternative splicing to such diversity by analyzing the dynamics of a key hematopoietic regulator, HMGA2. Next, we showed that CLK3, by regulating the splicing pattern of HMGA2, reinforces an HSC-specific program

Smoking Cessation in Indigenous Populations of Australia, New Zealand, Canada, and the United States: Elements of Effective Interventions

Indigenous people throughout the world suffer a higher burden of disease than their non-indigenous counterparts contributing to disproportionate rates of disability. A significant proportion of this disability can be attributed to the adverse effects of smoking. In this paper, we aimed to identify and discuss the key elements of individual-level smoking cessation interventions in indigenous people worldwide. An integrative review of published peer-reviewed literature was conducted. Literature on smoking cessation interventions in indigenous people was identified via search of electronic databases. Documents were selected for review if they were published in a peer-reviewed journal, written in English, published from 1990–2010, and documented an individual-level intervention to assist indigenous people to quit smoking. Studies that met inclusion criteria were limited to Australia, New Zealand, Canada, and the USA, despite seeking representation from other indigenous populations. Few interventions tailored for indigenous populations were identified and the level of detail included in evaluation reports was variable. Features associated with successful interventions were integrated, flexible, community-based approaches that addressed known barriers and facilitators to quitting smoking. More tailored and targeted approaches to smoking cessation interventions for indigenous populations are required. The complexity of achieving smoking cessation is underscored as is the need to collaboratively develop interventions that are acceptable and appropriate to local populations

Developmental regulation of myeloerythroid progenitor function by the Lin28b–let-7–Hmga2 axis

For appropriate development, tissue and organ system morphogenesis and maturation must occur in synchrony with the overall developmental requirements of the host. Mistiming of such developmental events often results in disease. The hematopoietic system matures from the fetal state, characterized by robust erythrocytic output that supports prenatal growth in the hypoxic intrauterine environment, to the postnatal state wherein granulocytes predominate to provide innate immunity. Regulation of the developmental timing of these myeloerythroid states is not well understood. In this study, we find that expression of the heterochronic factor Lin28b decreases in common myeloid progenitors during hematopoietic maturation to adulthood in mice. This decrease in Lin28b coincides with accumulation of mature let-7 microRNAs, whose biogenesis is regulated by Lin28 proteins. We find that inhibition of let-7 in the adult hematopoietic system recapitulates fetal erythroid-dominant hematopoiesis. Conversely, deletion of Lin28b or ectopic activation of let-7 microRNAs in the fetal state induces a shift toward adult-like myeloid-dominant output. Furthermore, we identify Hmga2 as an effector of this genetic switch. These studies provide the first detailed analysis of the roles of endogenous Lin28b and let-7 in the timing of hematopoietic states during development