Proton translocating nicotinamide nucleotide transhydrogenase from E. coli. Mechanism of action deduced from its structural and catalytic properties11This review is dedicated to the memory of Professor Lars Ernster.

AbstractTranshydrogenase couples the stereospecific and reversible transfer of hydride equivalents from NADH to NADP+ to the translocation of proton across the inner membrane in mitochondria and the cytoplasmic membrane in bacteria. Like all transhydrogenases, the Escherichia coli enzyme is composed of three domains. Domains I and III protrude from the membrane and contain the binding site for NAD(H) and NADP(H), respectively. Domain II spans the membrane and constitutes at least partly the proton translocating pathway. Three-dimensional models of the hydrophilic domains I and III deduced from crystallographic and NMR data and a new topology of domain II are presented. The new information obtained from the structures and the numerous mutation studies strengthen the proposition of a binding change mechanism, as a way to couple the reduction of NADP+ by NADH to proton translocation and occurring mainly at the level of the NADP(H) binding site

Gratistidningar -Ett utbrett fenomen, Varför?

Uppsatsen syftar till att utifrån både ett producentperspektiv och ett konsumentperspektiv undersöka och belysa tänkbara anledningar till att gratistidningar har blivit ett utbrett fenomen. Primärdata har samlats in med hjälp av följande metoder: 1. En enkätundersökning kring gratistidningskonsumenter. 2. Genomläsning av gratistidningar samt observationer av gratistidningsutgivares konkurrenspräglade distributionsbeteende. Sekundärdata har till största del hämtats från elektroniska källor, artiklar och rapporter. Insamlad information har analyserats med hjälp av teoretiska modeller som behandlar konsumenters livsstil samt olika marknadsinträdesstrategier hos gratistidningsutgivare. Uppsatsen har avgränsats genom att enbart undersöka fenomenet gratistidningar och dess utbredning i Malmö/Lundregionen. Uppsatsens resultat visar på att gratistidningarnas utbredning i större utsträckning kan förklaras genom mediekoncerners marknadsintressen än genom gratistidningsläsares livsstil och medföljande konsumtionsmönster

Quantification of the Impact of Temperature, CO2, and Rainfall Changes on Swedish Annual Crops Production Using the APSIM Model

Ongoing climate change is already affecting crop production patterns worldwide. Our aim was to investigate how increasing temperature and CO2 as well as changes in precipitation could affect potential yields for different historical pedoclimatic conditions at high latitudes (i.e., >55°). The APSIM crop model was used to simulate the productivity of four annual crops (barley, forage maize, oats, and spring wheat) over five sites in Sweden ranging between 55 and 64°N. A first set of simulations was run using site-specific daily weather data acquired between 1980 and 2005. A second set of simulations was then run using incremental changes in precipitation, temperature and CO2 levels, corresponding to a range of potential future climate scenarios. All simulation sets were compared in terms of production and risk of failure. Projected future trends showed that barley and oats will reach a maximum increase in yield with a 1°C increase in temperature compared to the 1980–2005 baseline. The optimum temperature for spring wheat was similar, except at the northernmost site (63.8°N), where the highest yield was obtained with a 4°C increase in temperature. Forage maize showed best performances for temperature increases of 2–3°C in all locations, except for the northernmost site, where the highest simulated yield was reached with a 5°C increase. Changes in temperatures and CO2 were the main factors explaining the changes in productivity, with ~89% of variance explained, whereas changes in precipitation explained ~11%. At the northernmost site, forage maize, oats and spring wheat showed decreasing risk of crop failure with increasing temperatures. The results of this modeling exercise suggest that the cultivation of annual crops in Sweden should, to some degree, benefit from the expected increase of temperature in the coming decades, provided that little to no water stress affects their growth and development. These results might be relevant to agriculture studies in regions of similar latitudes, especially the Nordic countries, and support the general assumption that climate change should have a positive impact on crop production at high latitudes

Challenges for Simulating Growth and Phenology of Silage Maize in a Nordic Climate with APSIM

APSIM Next Generation was used to simulate the phenological development and biomass production of silage maize for high latitudes (i.e., >55 degrees). Weather and soil data were carefully specified, as they are important drivers of the development and growth of the crop. Phenology related parameters were calibrated using a factorial experiment of simulations and the minimization of the root mean square error of observed and predicted phenological scaling. Results showed that the model performed well in simulating the phenology of the maize, but largely underestimated the production of biomass. Several factors could explain the discrepancy between observations and predictions of above-ground dry matter yield, such as the current formalization of APSIM for simulating the amount of radiation absorbed by the crop at high latitudes, as the amount of diffuse light and intercepted light increases with latitude. Another factor that can affect the accuracy of the predicted biomass is the increased duration of the day length observed at high latitudes. Indeed, APSIM does not yet formalize the effects of extreme day length on the balance between photorespiration and photosynthesis on the final balance of biomass production. More field measurements are required to better understand the drivers of the underestimation of biomass production, with a particular focus on the light interception efficiency and the radiation use efficiency

Komparatistik als Kulturwissenschaft?

Die Frage nach der Position der Komparatistik im Rahmen der kulturwissenschaftlichen Neuorientierung der Literaturwissenschaft berührt grundsätzlich das fachliche Selbstverständnis. Jede Standortbestimmung hängt deshalb wesentlich von den Vorstellungen ab, worin die Aufgaben und Kompetenzen der Komparatistik überhaupt bestehen sollen. Neben einer historischen Orientierung des Faches und einer von Fachvertreterin zu Fachvertreter unterschiedlichen Idealvorstellung, die jeweils viel mit dem persönlichen akademischen und wissenschaftsbiographischen Werdegang zu tun hat, gilt es deshalb auch, die institutionellen Rahmenbedingungen in den Blick zu nehmen

Chemically Modified Dendritic Starch: A Novel Nanomaterial for siRNA Delivery

Nanostructured starches are naturally derived nanomaterials that can be chemically modified to allow for the introduction of functional groups, enhancing their potential for drug delivery and other biotechnology applications. In this proof of concept study, we investigate chemically modified, enzymatically synthesized glycogen (ESG) nanodendrites as a biodegradable, biocompatible, siRNA delivery system. Commercially available ESG was modified using glycidyltrimethylammonium chloride (GTMA), introducing quaternary ammonium groups via an epoxide ring opening reaction. This cationic ESG (cESG) electrostatically bound siRNA and successfully knocked down protein expression in an in vitro ovarian clear cell carcinoma model. The construct exhibited sustained siRNA delivery for up to 6 days while exhibiting less toxicity than a common liposome-based siRNA delivery reagent, Lipofectamine RNAiMAX. These promising results set the stage for the use of dendritic starch as a cost-effective, easily modifiable nanoscale delivery system for a diverse range of cargo including nucleic acids and therapeutic compounds

Zein nanocapsules as a tool for surface passivation, drug delivery and biofilm prevention

Current oral hygiene treatments focus on managing oral biofilms (i.e. dental plaque) by broad antimicrobial strategies, indiscriminately killing both pathogenic and commensal microorganisms present in the oral cavity. In an effort to identify alternative approaches to antimicrobials, several research groups, including our own, have identified small molecule inhibitors that interrupt cell-cell signaling and biofilm formation, with potential to be selective against pathogens while leaving commensal flora unperturbed. A drawback to such inhibitors is their limited efficacy when used in acute exposures (e.g. mouthwash or brushing). In order to enhance bioavailability and maximize efficacy of these agents in a complex and dynamic environment such as the oral cavity, it is necessary to maintain a constant reservoir of the agents in situ. Therefore, we formulated a biofilm inhibitor delivery system by encapsulating an inhibitor of Streptococcus mutans biofilm formation, S-phenyl-L-cysteine sulfoxide, into zein nanocapsules. Nanocapsules formed 110–235 nm particles in a liquid-liquid dispersion synthesis procedure with S-phenyl-L-cysteine sulfoxide, as determined by dynamic light scattering. The inhibitor-loaded nanocapsules were then used to cast a film and subsequent S. mutans biofilm formation at this surface was studied. Nanocapsule films loaded with biofilm inhibitors were shown to deter early S. mutans biofilm development at 24 h, as well as reduce total viable biofilm-recovered cells at 48 h. This demonstrates proof-of-concept that biofilm inhibitor-loaded zein nanocapsules can reduce S. mutans biofilm growth, and demonstrates a new approach to extend the time that dental plaque inhibitors are present at the tooth surface. This approach has the potential to delay recolonization of the tooth and reduce oral infection/disease