Comprehensive prediction of chromosome dimer resolution sites in bacterial genomes

<p>Abstract</p> <p>Background</p> <p>During the replication process of bacteria with circular chromosomes, an odd number of homologous recombination events results in concatenated dimer chromosomes that cannot be partitioned into daughter cells. However, many bacteria harbor a conserved dimer resolution machinery consisting of one or two tyrosine recombinases, XerC and XerD, and their 28-bp target site, <it>dif</it>.</p> <p>Results</p> <p>To study the evolution of the <it>dif/</it>XerCD system and its relationship with replication termination, we report the comprehensive prediction of <it>dif </it>sequences <it>in silico </it>using a phylogenetic prediction approach based on iterated hidden Markov modeling. Using this method, <it>dif </it>sites were identified in 641 organisms among 16 phyla, with a 97.64% identification rate for single-chromosome strains. The <it>dif </it>sequence positions were shown to be strongly correlated with the GC skew shift-point that is induced by replicational mutation/selection pressures, but the difference in the positions of the predicted <it>dif </it>sites and the GC skew shift-points did not correlate with the degree of replicational mutation/selection pressures.</p> <p>Conclusions</p> <p>The sequence of <it>dif </it>sites is widely conserved among many bacterial phyla, and they can be computationally identified using our method. The lack of correlation between <it>dif </it>position and the degree of GC skew suggests that replication termination does not occur strictly at <it>dif </it>sites.</p

Conceptualizing and measuring strategy implementation – a multi-dimensional view

Through quantitative methodological approaches for studying the strategic management and planning process, analysis of data from 208 senior managers involved in strategy processes within ten UK industrial sectors provides evidence on the measurement properties of a multi-dimensional instrument that assesses ten dimensions of strategy implementation. Using exploratory factor analysis, results indicate the sub-constructs (the ten dimensions) are uni-dimensional factors with acceptable reliability and validity; whilst using three additional measures, and correlation and hierarchical regression analysis, the nomological validity for the multi-dimensional strategy implementation construct was established. Relative importance of ten strategy implementation dimensions (activities) for practicing managers is highlighted, with the mutually and combinative effects drawing conclusion that senior management involvement leads the way among the ten key identified activities vital for successful strategy implementation

‘Introduction: British World Policy and the White Queen’s Memory’

Scholars of Britain’s external relations in the nineteenth and twentieth centuries readily acknowledge the global nature of their subject. Yet in practice, they tend to dissect it along bilateral lines or with an exclusive focus on the imperial periphery. The tension between Britain’s global strategic interests and its ability to safeguard them has likewise long been the subject of scholarly debates, invariably accompanied by more or less explicit assumptions about the nation’s decline in the twentieth century. Already Arnold J. Toynbee, in reflecting on the origins of the Second World War, contrasted Britain’s assumed position as ‘the arbiter of Europe’ from around the time of the War of the Spanish Succession at the beginning of the eighteenth century until the final years of peace before 1914 with the country’s reduced circumstances in the interwar period

‘“The Diplomatic Digestive Organ”':The Foreign Office as the Nerve Centre of Foreign Policy, c. 1800-1940

Foreign ministries form a central part of modern diplomatic practice. They emerged slowly and haphazardly from the late fifteenth century onwards. With the growth in scope – both geographical and temporal – and intensity of diplomacy came the need for a central organization that could control and coordinate policy at the seat of government. In Tudor and Elizabethan England, too, the steady growth of diplomatic activity spurred on institutional change in the shape of the Principal Secretary of State. Initially, an officer of the royal household, executing the decisions of the monarch and the Privy Council, over time much of his business came to be focused on foreign affairs