Protect our pubs!

Protect Our Pubs! is a project examining the notion of the nationalisation of pubs by the state. It involved a protest, audio tours of the pub, posters protesting at the notion, a contest for the smartest barperson, peg drinking contest, a flighting contest and various documentation. The protest and subsequent events took place at the Hare & Hounds Pub in the Midlands

Glycine Betaine Fluxes in Lactobacillus plantarum during Osmostasis and Hyper- and Hypo-osmotic Shock

Bacteria respond to changes in medium osmolarity by varying the concentrations of specific solutes in order to maintain constant turgor. The primary response of Lactobacillus plantarum to an osmotic upshock involves the accumulation of compatible solutes such as glycine betaine, proline, and glutamate. We have studied the osmotic regulation of glycine betaine transport in L. plantarum by measuring the overall and unidirectional rates of glycine betaine uptake and exit at osmostasis, and under conditions of osmotic upshock and downshock. At steady state conditions, a basal flux of glycine betaine (but no net uptake or efflux) is observed that amounts to about 20% of the rate of “activated” uptake (uptake at high osmolarity). No direct exchange of 14C-labeled glycine betaine in the medium for unlabeled glycine betaine in the cytoplasm was observed in glucose metabolizing and resting cells, indicating that a separate glycine betaine efflux system is responsible for the exit of glycine betaine. Upon osmotic upshock, the uptake system for glycine betaine is rapidly activated (within seconds), whereas the basal efflux is inhibited. These two responses account for a rapid accumulation of glycine betaine until osmostasis is reached. Upon osmotic downshock, glycine betaine is rapidly released by the cells in a process that has two kinetic components, i.e. one with a half-life of less than 2 s which is unaffected by the metabolic status of the cells, the other with a half-life of 4–5 min in glucose-metabolizing cells which is dependent on internal pH or a related parameter. We speculate that the former activity corresponds to a stretch-activated channel, whereas the latter may be facilitated by a carrier protein. Glycine betaine uptake is strongly inhibited immediately after an osmotic downshock, but slowly recovers in time. These studies demonstrate that in L. plantarum osmostasis is maintained through positive and negative regulation of both glycine betaine uptake and efflux, of which activation of uptake upon osmotic upshock and activation of a “channel-like” activity upon osmotic downshock are quantitatively most important.

Terahertz Response of Acoustically-Driven Optical Phonons

The manipulation of TO-phonon polaritons and the terahertz (THz) light field associated with them by means of an ultra-sound acoustic wave is proposed and illustrated by calculating the TO-phonon-mediated THz response of acoustically-pumped CuCl and TlCl crystals. We show the high-contrast acoustically-induced change of the THz reflectivity alongside with multiple THz Bragg replicas, which are associated with the infrared-active TO-phonon resonance driven by the ultrasonic wave. The effect, which stems from phonon anharmonicity, refers to an operating acoustic intensity I_ac ~ 1-100 kW/cm^2 and frequency nu_ac ~ 0.1 - 1 GHz, with possible applications in THz spectroscopy.Comment: 10 pages, 4 figure

Energy transducing processes in growing and starving lactic acid streptococcci

The investigations described in this thesis deal with these aspects with emphasis on the regulation of energy transducing processes. In addition, extensive attention has been paid to the (eco)physiological significance of the observed regulatory mechanisms. Zie: Summar

Computer modelling applied to the Calvin Cycle

This thesis developes computer modelling techniques, and their use in the investigation of biochemical systems, principally the photosynthetic Calvin cycle. A set of metabolic modelling software tools, "Scampi", constructed as part of this project is presented. A unique feature of Scampi is that it allows the user to make a particular model the subject of arbitrary algorithms. This provides a much greater flexibility than is available with other metabolic modelling software, and is necessary for work on models of (or approaching) realistic complexity. A detailed model of the Calvin cycle is introduced. It differs from previously published models of this system in that all reactions are assigned explicit rate equations (no equilibrium assumptions are made), and it includes the degradation, as well as the synthesis, of starch. The model is later extended to include aspects of the thioredoxin system, and oxidative pentose phosphate pathway. Much of the observed behaviour is consistent with experimental observation. In particular, Metabolic Control Analysis of the model shows that control of assimilation flux is likely to be shared between two enzymes, rubisco and sedoheptulose bisphosphotase (SBPase), and can readily be transferred between them. This appears to offer an explanation of experimental evidence, obtained by genetic manipulation, that both of these enzymes can exert high control over assimilation. A further finding is that the output fluxes from the cycle (to starch and the cytosol), show markedly different patterns of control from assimilation, and from each other. An novel observation in behaviour of the Calvin cycle model is that, under certain circumstances, particularly at low light levels, the model has two steady-states and can be induced to switch between them. Although this exact behaviour has not been described experimentally, published results show charecteristics suggesting the potential is there in vivo. An explanation of all the observed behaviour is proposed, based upon the topology of the model. If this is correct then it may be concluded that the qualitative behaviour observed in the model is to be expected in vivo, although the quantitative detail may vary considerably