Modeling of biomass smoke injection into the lower stratosphere by a large forest fire (Part I): reference simulation

Wildland fires in boreal regions have the potential to initiate deep convection, so-called pyro-convection, due to their release of sensible heat. Under favorable atmospheric conditions, large fires can result in pyro-convection that transports the emissions into the upper troposphere and the lower stratosphere. Here, we present three-dimensional model simulations of the injection of fire emissions into the lower stratosphere by pyro-convection. These model simulations are constrained and evaluated with observations obtained from the Chisholm fire in Alberta, Canada, in 2001. The active tracer high resolution atmospheric model (ATHAM) is initialized with observations obtained by radiosonde. Information on the fire forcing is obtained from ground-based observations of the mass and moisture of the burned fuel. Based on radar observations, the pyro-convection reached an altitude of about 13 km, well above the tropopause, which was located at about 11.2 km. The model simulation yields a similarly strong convection with an overshoot of the convection above the tropopause. The main outflow from the pyro-convection occurs at about 10.6 km, but a significant fraction (about 8%) of the emitted mass of the smoke aerosol is transported above the tropopause. In contrast to regular convection, the region with maximum updraft velocity in the pyro-convection is located close to the surface above the fire. This results in high updraft velocities >10 m s^−1 at cloud base. The temperature anomaly in the plume decreases rapidly with height from values above 50 K at the fire to about 5 K at about 3000 m above the fire. While the sensible heat released from the fire is responsible for the initiation of convection in the model, the release of latent heat from condensation and freezing dominates the overall energy budget. Emissions of water vapor from the fire do not significantly contribute to the energy budget of the convection

Oligomeric Status and Nucleotide Binding Properties of the Plastid ATP/ADP Transporter 1: Toward a Molecular Understanding of the Transport Mechanism

Background: Chloroplast ATP/ADP transporters are essential to energy homeostasis in plant cells. However, their molecular mechanism remains poorly understood, primarily due to the difficulty of producing and purifying functional recombinant forms of these transporters. Methodology/Principal Findings: In this work, we describe an expression and purification protocol providing good yields and efficient solubilization of NTT1 protein from Arabidopsis thaliana. By biochemical and biophysical analyses, we identified the best detergent for solubilization and purification of functional proteins, LAPAO. Purified NTT1 was found to accumulate as two independent pools of well folded, stable monomers and dimers. ATP and ADP binding properties were determined, and Pi, a co-substrate of ADP, was confirmed to be essential for nucleotide steady-state transport. Nucleotide binding studies and analysis of NTT1 mutants lead us to suggest the existence of two distinct and probably inter-dependent binding sites. Finally, fusion and deletion experiments demonstrated that the C-terminus of NTT1 is not essential for multimerization, but probably plays a regulatory role, controlling the nucleotide exchange rate. Conclusions/Significance: Taken together, these data provide a comprehensive molecular characterization of a chloroplas

Chloroplasts lacking class I glutaredoxins are functional but show a delayed recovery of protein cysteinyl redox state after oxidative challenge

Redox status of protein cysteinyl residues is mediated via glutathione (GSH)/glutaredoxin (GRX) and thioredoxin (TRX)-dependent redox cascades. An oxidative challenge can induce post-translational protein modifications on thiols, such as protein S-glutathionylation. Class I GRX are small thiol-disulfide oxidoreductases that reversibly catalyse S-glutathionylation and protein disulfide formation. TRX and GSH/GRX redox systems can provide partial backup for each other in several subcellular compartments, but not in the plastid stroma where TRX/light-dependent redox regulation of primary metabolism takes place. While the stromal TRX system has been studied at detail, the role of class I GRX on plastid redox processes is still unknown. We generate knockout lines of GRXC5 as the only chloroplast class I GRX of the moss Physcomitrium patens. While we find that PpGRXC5 has high activities in GSH-dependent oxidoreductase assays using hydroxyethyl disulfide or redox-sensitive GFP2 as substrates in vitro, Δgrxc5 plants show no detectable growth defect or stress sensitivity, in contrast to mutants with a less negative stromal EGSH (Δgr1). Using stroma-targeted roGFP2, we show increased protein Cys steady state oxidation and decreased reduction rates after oxidative challenge in Δgrxc5 plants in vivo, indicating kinetic uncoupling of the protein Cys redox state from EGSH. Compared to wildtype, protein Cys disulfide formation rates and S-glutathionylation levels after H2O2 treatment remained unchanged. Lack of class I GRX function in the stroma did not result in impaired carbon fixation. Our observations suggest specific roles for GRXC5 in the efficient transfer of electrons from GSH to target protein Cys as well as negligible cross-talk with metabolic regulation via the TRX system. We propose a model for stromal class I GRX function in efficient catalysis of protein dithiol/disulfide equilibria upon redox steady state alterations affecting stromal EGSH and highlight the importance of identifying in vivo target proteins of GRXC5

‘Change Today, Choose Fairtrade’ Fairtrade Fortnight and the citizen-consumer

The Fairtrade consumer is widely represented as an individual who intentionally and reflexively consumes Fairtrade goods in order to register their support for the plight of producers in the developing world. This figure is imagined to ‘vote’ with her/his pocket every time they visit the supermarket thus demonstrating their commitment to the Fairtrade trading model. However, this image of the Fairtrade citizen-consumer does not emerge automatically as a response to the increasing availability of Fairtrade goods in the market-place but has to be made by various intermediary actors and organizations. This paper examines how the Fairtrade consumer was constructed and called to action by the Fairtrade Fortnight promotional campaign that occurred within the UK in 2008 and was co-ordinated by the Fairtrade Foundation. This annual event offers a unique window into the processes and actors involved in the mobilization of the Fairtrade citizen-consumer. Through a close focus on the promotional material distributed to different audiences and the events that occurred during this Fortnight, this paper reveals the contingent and shifting nature of the citizen-consumer identity. In so doing, it highlights how varying degrees of reflexivity and action are demanded of different audiences and how this shapes the way that Fairtrade goods are qualified and distributed in the market

New Faces and New Masks of Today's Consumer

In 1995, we proposed that consumption and contemporary consumerism could not be studied or understood separately from the world of work and production. We proposed that contemporary consumerism was built on the back of what we referred to as `the Fordist Deal'. This deal, pioneered by Henry Ford for his employees, was the promise of ever increasing standards of living in exchange for a quiescent labour force accepting alienating work. Since that deal was struck, consumerism came to signify a general pre-occupation with consumption standards and choice as well as a willingness to read meanings in material commodities and to equate happiness and success with material possessions. In this sense, Ford may be seen as the father both of mass production and mass consumption. Since the Fordist high noon of consumerism in the West, mass consumption is widely seen as having fragmented into a proliferation of highly individualized niche products. For its part, a considerable part of mass production has migrated to countries with lower wages and looser environmental and social controls, fueling their own variants of consumerism. In this article, we examine the gradual erosion of the Fordist Deal in the light of developments in the last 10 years or so, seeking to assess the future of consumerism at a global level. We also seek to identify and discuss some emerging conceptualizations of the consumer, some of the new faces and masks assumed by the archetypal character of our types. We analyse some of the tensions and contradictions lurking behind these conceptualizations and try to envisage some of the real choices facing consumers today and some of the processes of social change that hinge on the outcomes of these choices. The article identifies a fundamental paradox between the ubiquity of the consumer in contemporary discourses and the virtual impossibility of generalizing about consumers. We suggest, then, that the consumer may be viewed as one of those `essentially contested concepts' proposed by Gallie that defy domestication. The consumer, we argue, is unmanageable, both as a concept, since no-one can pin it down to one specific conceptualization at the expense of all others, and as an entity, since attempts to control and manage the consumer lead to the consumer mutating from one impersonation to another. It is precisely this paradox that we seek to capture in our article's title. The article concludes with a consideration of three basic challenges that are liable to lead to fundamental reorientation of consumption and production, as well as of our conceptualizations and theorizing about them. These challenges are the outcomes of environmental, demographic and social factors that, we argue, make the current situation unsustainable and will bring about its dissolution

Legionella pneumophila Secretes a Mitochondrial Carrier Protein during Infection

The Mitochondrial Carrier Family (MCF) is a signature group of integral membrane proteins that transport metabolites across the mitochondrial inner membrane in eukaryotes. MCF proteins are characterized by six transmembrane segments that assemble to form a highly-selective channel for metabolite transport. We discovered a novel MCF member, termed Legionella nucleotide carrier Protein (LncP), encoded in the genome of Legionella pneumophila, the causative agent of Legionnaire's disease. LncP was secreted via the bacterial Dot/Icm type IV secretion system into macrophages and assembled in the mitochondrial inner membrane. In a yeast cellular system, LncP induced a dominant-negative phenotype that was rescued by deleting an endogenous ATP carrier. Substrate transport studies on purified LncP reconstituted in liposomes revealed that it catalyzes unidirectional transport and exchange of ATP transport across membranes, thereby supporting a role for LncP as an ATP transporter. A hidden Markov model revealed further MCF proteins in the intracellular pathogens, Legionella longbeachae and Neorickettsia sennetsu, thereby challenging the notion that MCF proteins exist exclusively in eukaryotic organisms