The interaction of the alpha-2 chimaerin SH2 domain with target proteins

Rac is a member of the Rho subfamily of low molecular weight GTPases (p21s) and is involved in diverse cellular processes. GTPase-activating proteins (GAPs) regulate p21 activity by increasing intrinsic GTPase activity. The chimaerins are a family of p21-Rac GAPS with distinct patterns of tissue and developmental distribution, α2 chimaerin contains an amino-terminal SH2 domain and is selectively expressed within the nervous system. SH2 domains bind specific phosphotyrosine-containing sequences and the presence of this domain may place α2 chimaerin within tyrosine kinase signalling pathways. Comparisons between SH2 domains suggest that the mechanism of target interaction of the chimaerin SH2 domain may be distinct from that of others. Affinity chromatography was used to detect potential α2 chimaerin SH2 domain target proteins in rat brain extracts; some of these proteins were tyrosine-phosphorylated. Tubulin and actin were isolated as targets and peptide sequence information was obtained for three other potential target proteins, two of which appeared to be novel sequences. Several different kinase activities bound α2 chimaerin SH2 domain affinity columns; one of these phosphorylated full length α2 chimaerin. Full length α2 chimaerin and its isolated SH2 domain bound a phosphotyrosine column. Amino acid residue substitutions were made in the α2 chimaerin SH2 domain at sites essential for function in other SH2 domains; certain point mutations affected phosphotyrosine-binding. α2 Chimaerin probes bound two previously identified putative α2 chimaerin target proteins of molecular mass 13kDa and 64kDa; these interactions were phosphotyrosine-independent. The interactions of the 13kDa and 64kDa proteins with α2 chimaerin differed in their sensitivity to point mutation of the chimaerin SH2 domain. Specific antibodies have been raised to these proteins to facilitate further studies. Results suggest that substrates of the α2 chimaerin SH2 domain may include both tyrosine-phosphorylated and non-tyrosine phosphorylated proteins

Measurement and prediction of CO2 solubility in sodium phosphate monobasic solutions for food treatment with high pressure carbon dioxide

Two experimental systems were designed and tested to measure the CO2 solubility in sodium dibasic phosphate solutions (0.276, 2.76 and 5.52 g/100 g water) at different pressures (7.5 and 15.0 MPa) and temperatures (35, 40 and 50°C). The results were compared with those for pure water. Three thermodynamic solubility models were tested using the Aspen Simulation PlusTM software: 1) Peng-Robinson equation of state (EOS), where the a and b parameters were evaluated with the Wong and Sandler mixing rules (PRWS) and the activity coefficients were defined using the functional groups with the modified UNIFAC method 2) Electrolytic non-random two liquids (ELECNRTL) with the Redlich-Kwong equation of state for aqueous and mixed solvent applications 3) The completely predictive Soave-Redlich-Kwong (PSRK) equation of state. CO2 solubility was a strong function of sodium dibasic phosphate concentrations. The predictions of the PRWS EOS agreed well with the experimental data in the pressure and temperature ranges tested. A higher difference between the experimental and predicted results was observed for conditions close to the CO2 critical point and for low sodium dibasic phosphate concentrations. Thermodynamic models 2 and 3 predictions had a much higher deviations from experimental data

Effects of field inoculation with VAM and bacteria consortia on root growth and nutrients uptake in common wheat

This study investigated the effects of a commercial biofertilizer containing the mycorrhizal fungus Rhizophagus irregularis and the diazotrophic N-fixing bacterium Azotobacter vinelandii on root and shoot growth, yield, and nutrient uptake in common wheat (Triticum aestivum L.) in order to improve the sustainable cultivation of this widespread crop. The trials were carried out in controlled conditions (rhizoboxes) and in open fields over two years to investigate the interaction between inoculation and three doses of nitrogen fertilization (160, 120 and 80 kg ha1) in a silty-loam soil of the Po Plain (NE Italy). In rhizoboxes, efficient root colonization by R. irregularis was observed at 50 days after sowing with seed inoculation, together with improved root tip density and branching (+~30% vs. controls), while the effects of post-emergence inoculation by soil and foliar spraying were not observable at plant sampling. In the open, field spraying at end tillering significantly increased the volumetric root length density (RLD, +22% vs. controls) and root area density (+18%) after about two months (flowering stage) in both years under medium and high N fertilization doses, but not at the lowest N dose. In absence of inoculation, RLD progressively decreased with increased N doses. Inoculation had a negligible effect on grain yield and N uptake, which followed a typical N dose-response model, while straw Zn, P, and K concentrations were seldom improved. It is concluded that medium-high N fertilization doses are required to achieve the target yield and standards of quality (protein contents) in wheat cultivation, while the use of this mixed VAM-PGPR biofertilizer appears to be a sustainable mean for minimizing the adverse effects of chemical N fertilizers on root expansion and for improving the uptake of low-mobility nutrients, which has potentially relevant environmental benefits

Immigrant Students and Educational Systems. Cross-Country Evidence from PISA 2006

Using data from PISA 2006 on 29 countries, this paper analyses immigrant school gaps (difference in scores between immigrants and natives) and focuses on tracking and comprehensive educational systems. Results show that the wider negative gaps are present where tracking is sharp and less frequently in countries with comprehensive schooling. In both cases, negative gaps are concentrated in continental Western Europe, where they are also often related to immigrants and natives attending different schools, or are significant within schools

QoS control of E-business systems through performance modelling and estimation

E-business systems provide the infrastructure whereby parties interact electronically via business transactions. At peak loads, these systems are susceptible to large volumes of transactions and concurrent users and yet they are expected to maintain adequate performance levels. Over provisioning is an expensive solution. A good alternative is the adaptation of the system, managing and controlling its resources. We address these concerns by presenting a model that allows fast evaluation of performance metrics in terms of measurable or controllable parameters. The model can be used in order to (a) predict the performance of a system under given or assumed loading conditions and (b) to choose the optimal configuration set-up for certain controllable parameters with respect to specified performance measures. Firstly, we analyze the characteristics of E-business systems. This analysis leads to the analytical model, which is sufficiently general to capture the behaviour of a large class of commonly encountered architectures. We propose an approximate solution which is numerically efficient and fast. By mean of simulation, we prove that its accuracy is acceptable over a wide range of system configurations and different load levels. We further evaluate the approximate solution by comparing it to a real-life E-business system. A J2EE application of non-trivial size and complexity is deployed on a 2-tier system composed of the JBoss application server and a database server. We implement an infrastructure fully integrated on the application server, capable of monitoring the E-business system and controlling its configuration parameters. Finally, we use this infrastructure to quantify both the static parameters of the model and the observed performance. The latter are then compared with the metrics predicted by the model, showing that the approximate solution is almost exact in predicting performance and that it assesses the optimal system configuration very accurately.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Phosphorylation of the DNA Polymerase -Primase B Subunit Is Dependent on Its Association with the p180 Polypeptide

The B subunit of the DNA polymerase (pol) alpha-primase complex executes an essential role at the initial stage of DNA replication in Saccharomyces cerevisiae and is phosphorylated in a cell cycle-dependent manner. In this report, we show that the four subunits of the yeast DNA polymerase alpha-primase complex are assembled throughout the cell cycle, and physical association between newly synthesized pol alpha (p180) and unphosphorylated B subunit (p86) occurs very rapidly. Therefore, B subunit phosphorylation does not appear to modulate p180.p86 interaction. Conversely, by depletion experiments and by using a yeast mutant strain, which produces a low and constitutive level of the p180 polypeptide, we found that formation of the p180.p86 subcomplex is required for B subunit phosphorylation

On the role and the origin of the gas pressure gradient in the discharge of fine solids from hoppers

The Brown and Richards (Principles of Powder Mechanics, Pergamon Press, Oxford, UK, 1970) correlation for the discharge rate of fine powders from a hopper was modified to account for the gas pressure gradient near the outlet. According to Dons*+ et al. (Chem. Eng. Sci. 52 (1997) 4291) there is a transition between a granular floow region and a suspended floow region near the hopper outlet. Brown and Richards (1970) stated that the particle discharge rate depends on the 9ow conditions just above this transition surface. In the modified equation that is developed to account for the gas pressure, a term including the gas pressure gradient at this surface appears. The gas pressure gradient is evaluated from the literature experimental results by considering the Donsì et al. (1997) finding that a significant part of the gas pressure gradient near the hopper outlet is due to the suspended motion. Furthermore, a simplified analysis is carried out to evaluate from the experimental results the voidage variation within the solids phase that is responsible for the onset of the gas pressure gradient

Comparison of Bacterial and Archaeal Microbiome in Two Bioreactors Fed with Cattle Sewage and Corn Biomass

The bacterial and archaeal communities of two full-scale biogas producing plants (P1 and P2), associated with a 999 kW cogeneration unit, both located in North Italy, were analyzed at start up and fully operating phases, by means of various molecular approaches: (i) Automated Ribosomal Intergenic Spacer Analysis; (ii) cloning and sequencing of PCR amplicons of archaeal genes 16Srrna and mcrA; (iii) 16S rDNA high throughput next generation sequencing. P1 and P2 use the same technology and both were fed with cattle manure and corn silage. During the study of P1 also the post digester (fed with pig manure) was analyzed. The aim of this research was to characterize the bacterial and archaeal communities in two very similar plants to profile the core microbiota. The results of this analysis highlighted that the two plants (producing comparable quantities of volatile fatty acids, biogas, and energy) differed in anerobic microbiota (Bacteria and Archaea). Notably the methanogenic community of P1 was dominated by the strict acetoclastic Methanosaeta (Methanothrix) (up to 23.05%) and the unculturable Candidatus Methanofastidiosum (up to 32.70%), while P2 was dominated by the acetoclastic, but more substrate-versatile, Methanosarcina archaeal genus (49.19%). The data demonstrated that the performances of plants with identical design, in similar operating conditions, yielding comparable amount of biogas (average of 7237 m3 day−1 and 7916 m3 day−1 respectively for P1 and P2), VFA (1643 mg L− 1 and 1634 mg L−1) and energy recovery (23.90–24 MWh day−1), depend on the stabilization of effective and functionally optimized methanogenic communities, but these communities aretaxonomically different in the two biodigesters