Search

Dentin sialophosphoprotein (DSPP) is a large precursor protein that is proteolyti-cally processed into a NH2-terminal fragment [composed of dentin sialoprolein (DSP) and a proteoglycan form (DSP-PG)] and a COOH-terminal fragment [dentin phosphoprotein (DPP)]. In vitro studies indicate that DPP is a strong initiator and regulator of hydroxyapatite crystal formation and growth, but the role(s) of the NH2-terminal fragment of DSPP (i.e. DSP and DSP-PG) in dentinogenesis remain unclear. This study focuses on the function of the NH2-terminal fragment of DSPP in dentinogenesis. Here, transgenic (Tg) mouse lines expressing the NHi-lerminal fragment of DSPP driven by a 3.6-kb type I collagen promoter (Col lal) were generated and cross-bred with Dspp null mice to obtain mice that express the transgene but.lack the endogenous Dspp (Dspp KO/DSP Tg). We found that dentin from the Dspp KO/DSP Tg mice was much thinner, more poorly mineralized, and remarkably disorganized compared with dentin from the Dspp KO mice. The fact that Dspp KO/DSP Tg mice exhibited more severe dentin defects than did the Dspp null mice indicates that the NHi-lerminal fragment of DSPP may inhibit dentin mineralization or may serve as an antagonist against the accelerating action of DPP and serve to prevent predentin from being mineralized too rapidly during dentinogenesis [ABSTRACT FROM AUTHOR]

Dentin sialophosphoprotein (DSPP) in the extracellular matrix of dentin is cleaved into dentin sialoprotein and dentin phosphoprotein, which originate from the NH2-terminal and COOH-terminal regions of DSPP, respectively. In the proteolytic processing of mouse DSPP, the peptide bond at Gly451-Asp452 has been shown to be cleaved by bone morphogenetic protein 1 (BMP1)/Tolloid-like metalloproteinases. In this study, we generated transgenic mice expressing a mutant DSPP in which Asp452 was substituted by Ala452. Protein chemistry analyses of extracts from the long bone of these transgenic mice showed that the D452A substitution partially blocked DSPP processing in vivo. When the full-length form of mutant DSPP (designated 'D452A-DSPP') isolated from the transgenic mice was treated with BMP1 in vitro, a portion of the D452A-DSPP was cleaved, suggesting the presence of secondary peptide bond(s) that can be broken by BMP1. To identify the potential secondary DSPP cleavage site(s), site-directed mutagenesis was performed to generate nine DNA constructs expressing DSPP-bearing substitutions at potential scission sites. These different types of mutant DSPP made in eukaryotic cell lines were treated with BMP1 and the digestion products were assessed by Western immunoblotting. All of the mutant DSPP molecular species were partially cleaved by BMP1, giving rise to a protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis similar to that of normal dentin sialoprotein. Taken together, we concluded that in addition to the peptide bond Gly451-Asp452, there must be a cryptic cleavage site or sites close to Asp452 in the mouse DSPP that can be cleaved by BMP1. [ABSTRACT FROM AUTHOR]

A method is developed for retrieving atmospheric refractivity profiles in real time from the slant path tropospheric delay (STD) at low elevations (<5°) of a single ground-based Global Positioning System (GPS) receiver. The technique for retrieving atmospheric profiles proposed herein is based on a relevance vector machine (RVM), which is a sparse approximate Bayesian kernel method. The RVM network is trained by using historical radiosonde data, while the simulated STDs are calculated using the ray-tracing technique. The inputs of the network are surface meteorologic parameters and differences of the STDs at various elevations, while the outputs are tropospheric refractivity profiles for specific layers. The feasibility of this method is verified by both simulation and experiment. The STDs of the GPS receiver are obtained in the experiment by the undifferenced precise point position (PPP) method with International GPS Service (IGS) ultra-rapid products, which means that this method may be applied in real time. This article proposes a new method for retrieving atmospheric refractive profiles in real time at low cost and with high efficiency. [ABSTRACT FROM PUBLISHER]

Taxonomic diversity and temporal patterns in abundance of periphytic ciliate communities across taxonomic levels were studied to monitor water quality in Korean coastal waters during April 2007. Specifically we compared two methods based on an artificial substrate (glass slide): the polyurethane foam enveloped slide (PFES) and the conventional slide (CS) systems. The results demonstrated that: (1) the colonization patterns of the ciliate communities at all taxonomic levels showed a lower variability in the PFES system than those of the CS system; (2) The taxonomic diversity (Δ) and taxonomic distinctness (Δ*) were significantly higher in the PFES system than those in the CS system; and (3) all four taxonomic diversity/distinctness indices represented lower variability in the PFES system than those of the CS samples. These findings suggest that the PFES system is more effective than the CS system for measuring the colonization patterns and taxonomic distinctness parameters that are increasingly used as potential indicators of water quality. This conclusion supports our previous suggestion that the PFES system is a better tool than the CS system for monitoring water quality in the marine ecosystem, using periphytic ciliates. [ABSTRACT FROM PUBLISHER]

Focuses on the evolutionary relationships among human papillomavirus genotypes. Structural features of proteins; Divergence of the hinge region in E2; Degrees of sequence relatedness.

In this study, coal fly ash supported MnO 2 (CFA@MnO 2 ) was synthesized as heterocatalyst for the activation of peroxymonosulfate to degrade Acid Red 73 (AR73). The synthesized catalyst was characterized by X-Ray Fluorescence Spectrometer (XRF), X-ray powder diffraction (XRD), Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). The composite of CFA@MnO 2 possesses a large surface area of 74.59 m 2 /g. In the catalytic experiment, CFA@MnO 2 exhibits excellent catalytic performance with 99.13% AR73 removed within 40 min with a high kinetic rate constant of 0.124 min -1 , 5.49 times higher than that of pure MnO 2 . The operating parameters of CFA@MnO 2 -based fenton catalytic system were discussed, including MnO 2 loading, solution pH, PMS dosage and temperature. The catalyst maintained a relatively high removal rate (>85%) over 5 cycles and degradation intermediates are detected on the catalyst surface after cycled via XPS analysis. The degradation mechanism was investigated by quenching experiments and Electron Paramagnetic Resonance technology. The surface-bound · OH and SO 4 ·- are considered as the main active radicals in the degradation process. The composite of CFA@MnO 2 provides a low-cost and efficient alternative for the catalytic oxidation of organic pollutants.

Dentin sialophosphoprotein (DSPP) in the extracellular matrix of dentin is cleaved into dentin sialoprotein and dentin phosphoprotein, which originate from the NH(2)-terminal and COOH-terminal regions of DSPP, respectively. In the proteolytic processing of mouse DSPP, the peptide bond at Gly(451)-Asp(452) has been shown to be cleaved by bone morphogenetic protein 1 (BMP1)/Tolloid-like metalloproteinases. In this study, we generated transgenic mice expressing a mutant DSPP in which Asp(452) was substituted by Ala(452). Protein chemistry analyses of extracts from the long bone of these transgenic mice showed that the D452A substitution partially blocked DSPP processing in vivo. When the full-length form of mutant DSPP (designated "D452A-DSPP") isolated from the transgenic mice was treated with BMP1 in vitro, a portion of the D452A-DSPP was cleaved, suggesting the presence of secondary peptide bond(s) that can be broken by BMP1. To identify the potential secondary DSPP cleavage site(s), site-directed mutagenesis was performed to generate nine DNA constructs expressing DSPP-bearing substitutions at potential scission sites. These different types of mutant DSPP made in eukaryotic cell lines were treated with BMP1 and the digestion products were assessed by Western immunoblotting. All of the mutant DSPP molecular species were partially cleaved by BMP1, giving rise to a protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis similar to that of normal dentin sialoprotein. Taken together, we concluded that in addition to the peptide bond Gly(451)-Asp(452), there must be a cryptic cleavage site or sites close to Asp(452) in the mouse DSPP that can be cleaved by BMP1.