An ecological approach for estimating turbidity in a river

In purging and disposal of sediments operations of a reservoir it is necessary to know the values of turbidity in the river downstream in natural conditions. The paper shows that under these conditions, in the absence of dams or river training works, the ratio of the average values of sediment discharge to the annual maximum value of water discharge is a function of the average annual turbidity. Turbidity can be regarded as representative synthetic index of the climatic conditions, the lithological features and the land cover of the basin, and the geometric characteristics of the river network. The proposed relationship of sediment discharge as a function of water discharge were validated on the basis of data from in different regions of Italy, with very different morphological, geo-lithological and rainfall characteristics, and with basin area changing between a few dozen and thousands of square kilometres. The results can be considered satisfying

NMR backbone dynamics studies of human PED/PEA-15 outline protein functional sites

PEDPEA-15 (phosphoprotein enriched in diabetesphosphoprotein enriched in astrocytes) is a ubiquitously expressed protein and a key regulator of cell growth and glucose metabolism. PEDPEA-15 mediates both homotypic and heterotypic interactions and is constituted by an N-terminal canonical death effector domain and a C-terminal tail. In the present study, the backbone dynamics of PEDPEA-15 via 15N R1 and R2 and steady-state [1H]-15N NOE measurements is reported. The dynamic parameters were analyzed using both Lipari-Szabo model-free formalism and a reduced spectral density mapping approach. The results obtained define a polar and charged surface of the death effector domain characterized by internal motions in the micro- to millisecond timescale, which is crucial for the multiple heterotypic functional protein-protein interactions in which PEDPEA-15 is involved. The present study contributes to a better understanding of the molecular basis of the PEDPEA-15 functional interactions and provides a more detailed surface for the design and development of PEDPEA-15 binders. © 2010 FEBS

Catalytic systems based on Ce, Zr, K for soot oxidation

Systems based on Ce-Zr are used in catalytic converters for their oxygen storage ability. Recently, their application for soot abatement is under investigation. In this paper, preliminary results of the performance of Ce-Zr systems with the addition of K are reported by varying potassium content and calcination temperature. The powder catalysts were prepared by a variant of the citrates route developed at University of L'Aquila. Characterization of the catalysts after calcination was performed by different techniques: profile fitting of the XRD data, estimation of surface composition by XPS, evaluation of catalytic performance by temperature programmed oxidation tests of the soot-catalyst mixture and of redox properties by carbothermic reduction and subsequent oxidation in a high resolution thermobalance. The characterization by XRD showed that the system maintains the crystallographic structure Fm-3m and that the potassium is segregated on the grain boundaries. The catalytic activity results showed that the systems are particularly active even after 10 hours of calcination at 900 degrees C in fluidized bed. This temperature is high enough to get reasonably stable systems for practical applications. Moreover, the soot oxidation rate has a maximum at 368 degrees C in the sample with the best performance, therefore in the range of temperatures of diesel engine exhaust gases. The XPS data showed the presence of Ce, Zr, K and also of significant amount of Cl. Other formulations were prepared by adding small amounts of the different potassium halides

Expression and purification of the D4 region of PLD1 and characterization of its interaction with PED-PEA15.

PLD's (Phospholipases D) are ubiquitously expressed proteins involved in many transphosphatidylation reactions. They have a bi-lobed structure composed by two similar domains which at their interface reconstitute the catalytic site through the association of the two conserved HxKx(4)Dx(6)GSxN motifs. PLD1 interacts with the small phosphoprotein PED-PEA15 by an unknown mechanism that, by enhancing PLD1 stability, apparently increases its enzymatic activity; the minimum interacting region of PLD1 was previously identified as spanning residues 712-1074 (D4 region). Since the D4/PED-PEA15 interaction has been claimed to be one of the multiple molecular events that can trigger type 2 diabetes, we purified the two recombinant proteins to study in vitro this binding by both ELISA and SPR techniques. Whilst PED-PEA15 was easily expressed and purified, expression of recombinant D4 was more problematic and only the fusion protein with Thioredoxin A and a six Histidine Tag (Trx-His(6)-D4) demonstrated sufficient stability for further characterization. We have found that Trx-His(6)-D4 is present as two different oligomeric forms, though only the monomeric variant is able to interact with PED-PEA15. All these findings may have important implications for both the mechanisms of phospholipase activity and PED-PEA15 regulative functions