A proteomic analysis of the osmotic shock response in 'Salmonella enterica' serovar Typhimurium

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A proteomic analysis of the osmotic shock response in Salmonella enterica serovar Typhimurium

A reliable 2-dimensional gel electrophoresis methodology for the analysis of the Salmonella Typhimurium proteome was established and combined with mss spectrometry to detect and identify proteins that were differentially expressed when Salmonella was exposed to hyper-osmotic stress.  In wild type S. Typhimurium 24 proteins were differentially expressed, 13 were up-regulated and 11 down-regulated.  The proteins identified were involved in a range of bacterial systems including protein handling, protein synthesis, detoxification, metabolism and cell morphogenesis.  In addition, an ompR- mutant was used to determine which of these differentially expressed proteins were regulated by or independent of the OmpR/EnvZ regulatory system.  Generally, a similar set of components were differentially expressed in the ompR- mutant.  However, the degree of induction or repression tended to be exaggerated.  Additional analyses using the non-gel LC/MS based Protein Expression SystemTM strongly supported these results, further highlighting the up-regulation of proteins involved in cell morphogenesis, and also suggesting a subtle down-regulation of TCA cycle components. Two of the proteins that were highly induced by hyper-osmotic stress, and implicated in determining cell shape, where MreB and YgaU (the later was the most strongly induced protein, as detected by 2-D gel analyses, in both Salmonella strains).  Further mRNA analyses indicated that YgaU is transcriptionally up-regulated under hyper-osmotic stress, whereas MreB appears to be post-transcriptionally controlled.  Mutational analysis also confirmed that MreB is involved in cell morphology in Salmonella.</p

Colonial and Provincial Separation Movements in Australia and New Zealand, 1856-1865

This article examines separation movements in Britain\u27s Australasian colonies during the first decade of responsible government, 1856-65. Separation movements sought to carve new colonies from the territory of existing ones or, in the case of a number of New Zealand movements, to create new provinces within that colony\u27s quasi-federal system. Their demands rested upon assertions that a colonial or provincial government neglected large and prosperous hinterlands from which considerable revenue was collected. Only one colonial separation movement achieved its goal, but four provinces succeeded. I argue that responsible government played a major role in the success or failure of these movements. Responsibility concentrated authority in a remote capital; colonial separatists desired to exercise this privilege within a smaller new colony that they controlled, but its operation within the larger existing colony provided London with justification to reject most appeals. Further, it allowed New Zealand\u27s parliament to frame a mechanism that enabled discontented regions to become provinces without referral to local or imperial legislatures. Thus, I provide new insights into the formation of colonial polities and the influence of responsible government on settler political campaigns

Information in the term structure of yield curve volatility

We study volatility of US Treasuries. We propose a term structure model with stochastically correlated risks, which we estimate using realized volatilities and options. We identify time-varying volatilities and comovement of short-rate expectations and term premia. Volatility of short-rate expectations rises before recessions, predicts economic activity beyond the term spread, and covaries with measures of monetary policy uncertainty. Term premia become increasingly volatile in the aftermath of recessions and when economic policy uncertainty is high. Their correlation with expected short-rates fluctuates over time but is positive on average. Within an affine model, volatility has a small effect on the first moments of yields