Dienstleistungsarbeit im Zeichen von Vermarktlichung und neuer Leistungsorientierung

Der Aufsatz fasst den Stand der Forschung und die Beiträge des Sammelbandes "Dienstleistungsarbeit: Auf dem Boden der Tatsachen" (Hg. Pohlmann et al.), in Hinsicht auf die Bedeutung der Dienstleistungsarbeit für die Entwicklung moderner Gesellschaften zusammen. Er fragt nach Form und Stärke des erkennbaren Rationalisierungstrends, prüft den Trend zur Vermarktlichung und die Rolle der Arbeitsorientierung der Beschäftigten, und auch welche (nicht nur politischen) Gestaltungsperspektiven sich aus dieser Lage entwickeln lassen. Auf diese Weise zeichnet der Text ein differenziertes Bild der Dienstleistungsarbeit, als bevorzugtem Gegenstand betrieblicher Rationalisierungsbemühungen, mitsamt ihrer ambivalenten bis paradoxen Auswirkungen

Cooperation of the Conserved Aspartate 439 and Bound Amino Acid Substrate Is Important for High-Affinity Na+ Binding to the Glutamate Transporter EAAC1

The neuronal glutamate transporter EAAC1 contains several conserved acidic amino acids in its transmembrane domain, which are possibly important in catalyzing transport and/or binding of co/countertransported cations. Here, we have studied the effects of neutralization by site-directed mutagenesis of three of these amino acid side chains, glutamate 373, aspartate 439, and aspartate 454, on the functional properties of the transporter. Transport was analyzed by whole-cell current recording from EAAC1-expressing mammalian cells after applying jumps in voltage, substrate, or cation concentration. Neutralization mutations in positions 373 and 454, although eliminating steady-state glutamate transport, have little effect on the kinetics and thermodynamics of Na+ and glutamate binding, suggesting that these two positions do not constitute the sites of Na+ and glutamate association with EAAC1. In contrast, the D439N mutation resulted in an approximately 10-fold decrease of apparent affinity of the glutamate-bound transporter form for Na+, and an ∼2,000-fold reduction in the rate of Na+ binding, whereas the kinetics and thermodynamics of Na+ binding to the glutamate-free transporter were almost unchanged compared to EAAC1WT. Furthermore, the D439N mutation converted l-glutamate, THA, and PDC, which are activating substrates for the wild-type anion conductance, but not l-aspartate, into transient inhibitors of the EAAC1D439 anion conductance. Activation of the anion conductance by l-glutamate was biphasic, allowing us to directly analyze binding of two of the three cotransported Na+ ions as a function of time and [Na+]. The data can be explained with a model in which the D439N mutation results in a dramatic slowing of Na+ binding and a reduced affinity of the substrate-bound EAAC1 for Na+. We propose that the bound substrate controls the rate and the extent of Na+ interaction with the transporter, depending on the amino acid side chain in position 439

Early Intermediates in the Transport Cycle of the Neuronal Excitatory Amino Acid Carrier Eaac1

Electrogenic glutamate transport by the excitatory amino acid carrier 1 (EAAC1) is associated with multiple charge movements across the membrane that take place on time scales ranging from microseconds to milliseconds. The molecular nature of these charge movements is poorly understood at present and, therefore, was studied in this report in detail by using the technique of laser-pulse photolysis of caged glutamate providing a 100-μs time resolution. In the inward transport mode, the deactivation of the transient component of the glutamate-induced coupled transport current exhibits two exponential components. Similar results were obtained when restricting EAAC1 to Na+ translocation steps by removing potassium, thus, demonstrating (1) that substrate translocation of EAAC1 is coupled to inward movement of positive charge and, therefore, electrogenic; and (2) the existence of at least two distinct intermediates in the Na+-binding and glutamate translocation limb of the EAAC1 transport cycle. Together with the determination of the sodium ion concentration and voltage dependence of the two-exponential charge movement and of the steady-state EAAC1 properties, we developed a kinetic model that is based on sequential binding of Na+ and glutamate to their extracellular binding sites on EAAC1 explaining our results. In this model, at least one Na+ ion and thereafter glutamate rapidly bind to the transporter initiating a slower, electroneutral structural change that makes EAAC1 competent for further, voltage-dependent binding of additional sodium ion(s). Once the fully loaded EAAC1 complex is formed, it can undergo a much slower, electrogenic translocation reaction to expose the substrate and ion binding sites to the cytoplasm

Chanje Lavi Plantè in Haiti: Hillside soil conservation as a measure to increase yields and sequester carbon in Haiti

Analysis of the potential mitigation impacts of the agricultural development project Chanje Lavi Plantè in Haiti indicated that large amounts of carbon sequestration could be achieved through reforestation and perennial crop expansion. The project’s strategy for watershed and landscape restoration links investments in profitable orchard systems with hillside stabilization. Reforestation of watersheds (–478,828 tCO2e/yr) and perennial crop expansion (– 230,854 tCO2e/yr), drive 98% of the project’s sizable climate change mitigation co-benefits that are foreseen under successful project implementation. Chanje Lavi Plantè’s reduction in postharvest loss contribute to the reduced GHG emission intensity of cropping systems (GHG emissions per unit of production). Interventions are estimated to reduce postharvest loss substantially in these value chains: plantain (– 53%), maize (–47%), rice (–44%), beans (–50%) and mango (–35%). The investments made by the project in irrigation infrastructure, terracing, and forest plantations aim to increase financial revenues of beneficiaries and reinforce the lasting provision of ecosystem services

Diamondoid diacids ('O4' species) in oil sands process-affected water.

RATIONALE: As a by-product of oil sands extraction, large volumes of oil sands process water (OSPW) are generated, which are contaminated with a large range of water-soluble organic compounds. The acids are thought to be derived from hydrocarbons via natural biodegradation pathways such as α- and β-oxidation of alkyl substituents, which could produce mono- and diacids, for example. However, while several monoacids ('O2' species) have been identified, the presence of diacids (i.e. 'O4' species) has only been deduced from results obtained via Fourier transform infrared (FTIR) spectroscopy, Fourier transform ion cyclotron resonance high-resolution mass spectrometry (FTICR-HRMS) and nuclear magnetic resonance ((1)H-NMR) spectroscopy and the structures have never been confirmed. METHODS: An extract of an OSPW from a Canadian tailings pond was analysed and the retention times and the electron ionization mass spectra of some analytes were compared with those of bis-methyl esters of authentic diacids by gas chromatography × gas chromatography/time-of-flight mass spectrometry (GCxGC/TOFMS) in nominal and accurate mass configurations. RESULTS: Two diamondoid diacids (3-carboxymethyladamantane-1-carboxylic acid and adamantane-1,3-dicarboxylic acid) were firmly identified as their bis-methyl esters by retention time and mass spectral matching and several other structural isomers were more tentatively assigned. Diacids have substantially increased polarity over the hydrocarbon and monoacid species from which they probably derive: as late members of biodegradation processes they may be useful indicators of weathering and ageing, not only of OSPW, but potentially of crude oil residues more generally. CONCLUSIONS: Structures of O4 species in OSPW have been identified. This confirms pathways of microbial biodegradation, which were only postulated previously, and may be a further indication that remediation of OSPW toxicity can occur by natural microbial action. The presence and abundance of these diacids might therefore be useful as a measure of biodegradation and weathering

On the Mechanism of Proton Transport by the Neuronal Excitatory Amino Acid Carrier 1

Uptake of glutamate from the synaptic cleft is mediated by high affinity transporters and is driven by Na+, K+, and H+ concentration gradients across the membrane. Here, we characterize the molecular mechanism of the intracellular pH change associated with glutamate transport by combining current recordings from excitatory amino acid carrier 1 (EAAC1)–expressing HEK293 cells with a rapid kinetic technique with a 100-μs time resolution. Under conditions of steady state transport, the affinity of EAAC1 for glutamate in both the forward and reverse modes is strongly dependent on the pH on the cis-side of the membrane, whereas the currents at saturating glutamate concentrations are hardly affected by the pH. Consistent with this, the kinetics of the pre–steady state currents, measured after saturating glutamate concentration jumps, are not a function of the pH. In addition, we determined the deuterium isotope effect on EAAC1 kinetics, which is in agreement with proton cotransport but not OH− countertransport. The results can be quantitatively explained with an ordered binding model that includes a rapid proton binding step to the empty transporter followed by glutamate binding and translocation of the proton-glutamate-transporter complex. The apparent pK of the extracellular proton binding site is ∼8. This value is shifted to ∼6.5 when the substrate binding site is exposed to the cytoplasm

Resilience and Economic Growth in Arid Lands - Accelerated Growth in Kenya: Mitigation co-benefits of herd size and feed quality management

The agricultural development project Resilience and Economic Growth in Arid Lands – Accelerated Growth (REGAL-AG) has promoted improved livestock management that resulted in a decrease in net emissions of 10%. Since emissions from livestock account for the majority of Kenya’s agricultural emissions (95%), reduction of emissions in the livestock sector has high potential impact. REGAL-AG’s interventions have sought to improve links between livestock producers and buyers, to boost producer access to critical inputs, and to increase availability of timely market information, which resulted in a decrease in slaughter age for all livestock types. REGAL- AG anticipated that these dynamics, coupled with the program outreach activities, could result in a 10% decrease in herd size, which drives the greater share of emission reductions. Increases in productivity (50–67%) and decreases in absolute emissions (-10%) that resulted from REGAL-AG’s interventions decreased the emission intensity 33-40% (emissions per unit production) for all livestock types