958 research outputs found

    Dual-topology insertion of a dual-topology membrane protein.

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    Some membrane transporters are dual-topology dimers in which the subunits have inverted transmembrane topology. How a cell manages to generate equal populations of two opposite topologies from the same polypeptide chain remains unclear. For the dual-topology transporter EmrE, the evidence to date remains consistent with two extreme models. A post-translational model posits that topology remains malleable after synthesis and becomes fixed once the dimer forms. A second, co-translational model, posits that the protein inserts in both topologies in equal proportions. Here we show that while there is at least some limited topological malleability, the co-translational model likely dominates under normal circumstances

    Symposium—The Revised Washington Criminal Code

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    Bacteriorhodopsin folds through a poorly organized transition state.

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    The folding mechanisms of helical membrane proteins remain largely uncharted. Here we characterize the kinetics of bacteriorhodopsin folding and employ φ-value analysis to explore the folding transition state. First, we developed and confirmed a kinetic model that allowed us to assess the rate of folding from SDS-denatured bacteriorhodopsin (bRU) and provides accurate thermodynamic information even under influence of retinal hydrolysis. Next, we obtained reliable φ-values for 16 mutants of bacteriorhodopsin with good coverage across the protein. Every φ-value was less than 0.4, indicating the transition state is not uniquely structured. We suggest that the transition state is a loosely organized ensemble of conformations

    Peers in Prison Settings (PiPS) Expert Symposium

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    Addition of Inexpensive Lights to Aquatic Turtle Traps Improves Trapping Efficiency in Early Spring

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    Aquatic turtles are essential contributors to many freshwater ecosystems, but they face a myriad of threats, necessitating periodic monitoring of population status. Increasing turtle trapping efficiency has the potential to improve conservation efforts, particularly when population sizes are low or sampling conditions are suboptimal. In an effort to improve trapping efficiency, we added LED lights to turtle traps in an attempt to attract kinosternid turtles. Our investigation into the effectiveness of LED lights as an attractant was based on evidence suggesting that these turtles may forage using both visual and olfactory cues. Lights significantly increased captures of kinosternid turtles during early spring, but the increased efficiency did not persist later in the season, possibly due to lights facilitating escape from traps as turtle activity levels increased. To our knowledge, this study is the first research into the efficacy of using lights to increase trapping success of freshwater turtles. Given our encouraging results during early spring and the low cost of LED lights, we encourage researchers to explore the possibility of adding lights to traps to increase captures in challenging trapping conditions

    The significance of 'the visit' in an English category-B prison: Views from prisoners, prisoners' families and prison staff

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    A number of claims have been made regarding the importance of prisoners staying in touch with their family through prison visits, firstly from a humanitarian perspective of enabling family members to see each other, but also regarding the impact of maintaining family ties for successful rehabilitation, reintegration into society and reduced re-offending. This growing evidence base has resulted in increased support by the Prison Service for encouraging the family unit to remain intact during a prisoner’s incarceration. Despite its importance however, there has been a distinct lack of research examining the dynamics of families visiting relatives in prison. This paper explores perceptions of the same event – the visit – from the families’, prisoners’ and prison staffs' viewpoints in a category-B local prison in England. Qualitative data was collected with 30 prisoners’ families, 16 prisoners and 14 prison staff, as part of a broader evaluation of the visitors’ centre. The findings suggest that the three parties frame their perspective of visiting very differently. Prisoners’ families often see visits as an emotional minefield fraught with practical difficulties. Prisoners can view the visit as the highlight of their time in prison and often have many complaints about how visits are handled. Finally, prison staff see visits as potential security breaches and a major organisational operation. The paper addresses the current gap in our understanding of the prison visit and has implications for the Prison Service and wider social policy

    Expansions for the Bollobas-Riordan polynomial of separable ribbon graphs

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    We define 2-decompositions of ribbon graphs, which generalise 2-sums and tensor products of graphs. We give formulae for the Bollobas-Riordan polynomial of such a 2-decomposition, and derive the classical Brylawski formula for the Tutte polynomial of a tensor product as a (very) special case. This study was initially motivated from knot theory, and we include an application of our formulae to mutation in knot diagrams.Comment: Version 2 has minor changes. To appear in Annals of Combinatoric

    Well communities

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    Well Communities provides a framework for communities and local organisations (public, private and third sector) to work together to improve health and wellbeing, build resilience and reduce inequalities. Key concepts in engaging communities for social change and health improvement are integral to the Well Communities approach. These include whole systems, holistic and assets-based working, community engagement and community led action, community development and capacity building, co-production, positive psychology and empowerment. Through work over nine years with 33 of the most disadvantaged neighbourhoods in London, these concepts have been translated into a practical framework for actio

    Spanning Trees on Lattices and Integration Identities

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    For a lattice Λ\Lambda with nn vertices and dimension dd equal or higher than two, the number of spanning trees NST(Λ)N_{ST}(\Lambda) grows asymptotically as exp(nzΛ)\exp(n z_\Lambda) in the thermodynamic limit. We present exact integral expressions for the asymptotic growth constant zΛz_\Lambda for spanning trees on several lattices. By taking different unit cells in the calculation, many integration identities can be obtained. We also give zΛ(p)z_{\Lambda (p)} on the homeomorphic expansion of kk-regular lattices with pp vertices inserted on each edge.Comment: 15 pages, 3 figures, 1 tabl
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