Moving the research forward : the best of British biology using the tractable model system Dictyostelium discoideum

The social amoeba Dictyostelium discoideum provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and animal kingdoms around 1 billion years ago but retains common aspects found in these kingdoms. Dictyostelium has a low level of genetic complexity and provides a range of molecular, cellular, biochemical and developmental biology experimental techniques, enabling multidisciplinary studies to be carried out in a wide range of areas, leading to research breakthroughs. Numerous laboratories within the United Kingdom employ Dictyostelium as their core research model. This review introduces Dictyostelium and then highlights research from several leading British research laboratories, covering their distinct areas of research, the benefits of using the model, and the breakthroughs that have arisen due to the use of Dictyostelium as a tractable model system

Generation of H/sup -/, D/sup -/ ions on composite surfaces with application to surface/plasma ion source systems

We review some salient features of the experimental and theoretical data pertaining to hydrogen negative ion generation on minimum-work-function composite surfaces consisting of Cs/transition metal substrates. Cesium or hydrogen ion bombardment of a cesium-activated negatively-biased electrode exposed to a cesium-hydrogen discharge results in the release of hydrogen negative ions. These ions originate through desorbtion of hydrogen particles by incident cesium ions, desorbtion by incident hydrogen ions, and by backscattering of incident hydrogen. Each process is characterized by a specific energy and angular distribution. The calculation of ion formation in the crystal selvage region is discussed for different approximations to the surface potential. An ab initio, all-electron, local density functional model for the composite surface electronics is discussed

A Ras subfamily GTPase shows cell cycle-dependent nuclear localization

Previously characterized Ras subfamily proteins have been found to be predominantly associated with the plasma membrane where they function in signal transduction pathways to convey extracellular signals to intracellular targets. Here, we provide evidence that the Dictyostelium Ras subfamily protein RasB has a novel subcellular localization and function. The protein is predominantly localized in the nucleus during most of the cell cycle. Furthermore, during mitosis and cytokinesis RasB assumes a diffuse cellular localization despite the fact that the nuclear membrane stays intact. The linkage between the position of RasB in the cell and division suggests that it may have a role in nuclear division. Consistent with this idea, rasB(–) cells exhibit severe growth defects and cells overexpressing an activated version of RasB are multinucleate

A ‘Southern model’ of electoral mobilisation?: clientelism and electoral politics in post-Franco Spain

It is often argued that clientelism is a key feature of electoral mobilisation in Southern European democracies. This article examines the evidence for clientelism in the Spanish case, assessing the recruitment, redistributive strategies and electoral performance of governing parties in the 1977-96 period. It finds little evidence of extensive clientelistic mobilisation, finding instead that parties’ use of state resources is largely consistent with their programmatic and ideological positions. ‘Old’ clientelism from the pre-democratic era mostly did not survive the change of regime, whilst ‘new’ clientelism based on the expansion of state employment contributed to the Socialist Party’s organisational consolidation, but was not a significant feature of its strategy of electoral mobilisation