Trace element control in coal gasification : adsorption and thermodynamic equilibrium studies

Imperial Users onl

Autophosphorylation-based calcium (Ca2+) sensitivity priming and Ca2+/Calmodulin inhibition of Arabidopsis thaliana Ca2+-dependent protein kinase 28 (CPK28)

Plant calcium (Ca2+) dependent protein kinases (CPKs) are composed of a dual specificity (Ser/Thr and Tyr) kinase domain tethered to a Calmodulin-like domain (CLD) via an autoinhibitory junction (J) and represent the primary Ca2+-dependent protein kinase activities in plant systems. While regulation of CPKs by Ca2+ has been extensively studied, the contribution of autophosphorylation in the control of CPK activity is less well understood. Furthermore, whether Calmodulin (CaM) contributes to CPK regulation, as is the case for Ca2+/CaM-dependent protein kinases (CaMKs) outside the plant lineage, remains an open question. We screened a subset of plant CPKs for CaM-binding and found that CPK28 is a high-affinity Ca2+/CaM-binding protein. Using synthetic peptides and native gel electrophoresis, we coarsely mapped the CaM-binding domain to a site within the CPK28 J domain that overlaps with the known site of intramolecular interaction between the J domain and CLD. Peptide kinase activity of fully dephosphorylated CPK28 was Ca2+-responsive and inhibited by Ca2+/CaM. Using in situ autophosphorylated protein, we expand on the known set of CPK28 autophosphorylation sites, and demonstrate that, unexpectedly, autophosphorylated CPK28 had enhanced activity at physiological concentrations of Ca2+ compared to dephosphorylated protein, suggesting that autophosphorylation functions to prime CPK28 for Ca2+-activation. Furthermore, CPK28 autophosphorylation substantially reduced sensitivity of the kinase to Ca2+/CaM inhibition. Overall, our analyses uncover new complexities in the control of CPK28 and provide mechanistic support for Ca2+ signaling specificity through Ca2+ sensor priming

Calcium/calmodulin inhibition of the Arabidopsis BRASSINOSTEROID-INSENSITIVE 1 receptor kinase provides a possible link between calcium and brassinosteroid signalling

The receptor kinase BRI1 (BRASSINOSTEROID-INSENSITIVE 1) is a key component in BR (brassinosteroid) perception and signal transduction, and has a broad impact on plant growth and development. In the present study, we demonstrate that Arabidopsis CaM (calmodulin) binds to the recombinant cytoplasmic domain of BRI1 in a Ca2+-dependent manner in vitro. In silico analysis predicted binding to Helix E of the BRI1 kinase subdomain VIa and a synthetic peptide based on this sequence interacted with Ca2+/CaM. Co-expression of CaM with the cytoplasmic domain of BRI1 in Escherichia coli strongly reduced autophosphorylation of BRI1, in particular on tyrosine residues, and also reduced the BRI1-mediated transphosphorylation of E. coli proteins on tyrosine, threonine and presumably serine residues. Several isoforms of CaM and CMLs (CaM-like proteins) were more effective (AtCaM6, AtCaM7 and AtCML8, where At is Arabidopsis thaliana) than others (AtCaM2, AtCaM4 and AtCML11) when co-expressed with BRI1 in E. coli. These results establish a novel assay for recombinant BRI1 transphosphorylation activity and collectively uncover a possible new link between Ca2+ and BR signalling

Monitoring and improving non-financial variables for sustaining performance of a learning organisation following downsizing

In dynamic and turbulent markets, organisational restructuring is a necessary corporate process for companies to retain their competitive advantage. Unfortunately, global competitiveness pressures and economic downturn is causing companies to examine their cost structures and use employment downsizing as a management strategy for restructuring. If organisational downsizing may offer financial improvements in the short term, its profound personal and professional consequences on employees and negative impact on the dynamic and culture of the organisation are well known. Learning organisations strongly rely on the creativity and innovation of their knowledge workers to remain competitive, yet little consideration is placed on measuring the health of non-financial individual and organisational variables that influence knowledge worker's performance post downsizing and that are prone to reveal if the restructuring of the company will ensure "sustainable" performance. The research investigates the individual and organisational non-financial variables that post downsizing, are critical to evaluate and improve to ensure that the short term benefits obtained from restructuring the organisation are sustainable. The research is a case study of the research and technology division of a large South African industrial organisation that recently went through restructuring involving the layoff of personnel. From the research findings that identified critical variables impacting knowledge workers' creativity and innovation after restructuring as well as important interventions that would enable their job performance, a framework was developed to assist leaders in their change effort during and after restructuring. The objective of the framework is to enable and enhance the job performance of knowledge workers to sustain the performance of learning organisation in the future. The foundation of the framework is based on Kotter eight stage model and the combined Theory E (Economic value) & O (Organisation capability) change strategy. The framework draws links between Kotter's and Theory E&O change models and five key factors identified by knowledge workers to enable their performance at work after restructuring: (1) understanding the vision of the change, (2) ensuring relational and cognitive empowerment, (3) preserving the "innovation DNA", (4) having strong work ethics across the entire organisation and (5) developing systems and processes that are agile and efficient.Mini Dissertation (MBA)--University of Pretoria, 2017.ms2017Gordon Institute of Business Science (GIBS)MBAUnrestricte

Trace element control in coal gasification : adsorption and thermodynamic equilibrium studies

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Rotations culturales et modele : utilisation de dispositifs experimentaux.

National audienc

Expériences pluriannuelles sur les rotations culturales. Le point de vue d'un biométricien

International audienc

Comment lever la contrainte climatique sur l'hivernage des troupeaux ovins dans les Pyrenees? Les reponses apportees par des simulations.

National audienc

The farming system in the Pyrenees. A model of constitution of hay stocks.

International audienc

Working of the farming system in the Pyrenees. Elaboration of a model of constitution and utilization of the hay stock.

International audienc