Congenital defects of the bovine musculoskeletal system and joints

A variety of structural and functional congenital defects affecting the central nervous system of cattle have been identified. This article discusses specific defects of the central nervous system. Spastic and paralytic, metabolic, and storage diseases are reviewed.     

Elucidation of the mode of interaction of thermolysin with a proteinaceous metalloproteinase inhibitor, SMPI, based on a model complex structure and a structural dynamics analysis

SMPI is a proteinaceous microbial metalloproteinase inhibitor that was isolated from Streptomyces nigrescens TK-23 in 1979. SMPI is known to selectively inhibit the metalloproteinases in the gluzincin family, according to the Rawling and Barrett classification. There has been no report on the interaction of a metalloproteinase in the family of gluzincins with its specific proteinaceous inhibitor. We have solved the solution structure of SMPI by NMR. Here, we report the binding mode of SMPI to thermolysin, based on the model complex structure generated using our high-resolution NMR structure of SMPI and the crystal structure of thermolysin. The obtained complex model shows that the extruded loop of SMPI, with the scissile bond Cys64-Val65, is complementary in shape to the active cleft of thermolysin. In the complex, the Cys64 (P1) carbonyl oxygen atom can form a tetrahedral coordination to the active zinc in thermolysin, and simultaneously, the methyl groups of Val65 (P1') are closely located in the hydrophobic S1' pocket in thermolysin. From the electrostatic potential surface calculation, the active loop of SMPI and the active cleft in thermolysin have been shown to be complementary in the surface charge distribution, resulting in the stabilization of the complex. The apparently large active loop is less flexible, but maintains a conformation in the nano- to picosecond time-scale, as elucidated from the 15N spin relaxation analysis. This is a quite different structural feature of SMPI from the flexible binding loop generally found in the serine proteinase inhibitors, such as SSI and eglin c, and can be related to the narrow specificity of SMPI. The present study provides the first insight into the interaction between a proteinaceous inhibitor and a gluzincin metalloproteinase.     

Evolving autonomous specialization in congested path formation task of robotic swarms

Redundancy in the number of robots is a fundamental feature of robotic swarms to confer robustness, flexibility, and scalability. However, robots tend to interfere with each other in a case, where multiple robots gather in a spatially limited environment. The aim of this paper is to understand how a robotic swarm develops an effective strategy to manage congestion. The controllers of the robots are obtained by an evolutionary robotics approach. The strategy of managing congestion is observed in the process of generating a collective path of robots visiting two landmarks alternately. The robotic swarm exhibits autonomous specialization that the robots traveling inside the path activate the LEDs, while the robots in the outer side deactivate them. We found that the congestion is regulated in an emergent way of autonomous specialization by the result of an artificial evolution.     

Photocurrent generation properties of Histag-photosystem II immobilized on nanostructured gold electrode

It is well known that photosystem II (PSII) can produce electrons, oxygen, and protons simultaneously via a water-splitting photoreaction. These photochemical properties are expected to exhibit photoconductive function for PSII. In the present study, we have first observed a stable photocurrent due to the photoexcitation of PSII and the subsequent water-splitting reaction, by successfully immobilizing PSII on the self-assembled monolayer (SAM) of a nickel-nitrilotriacetic acid complex (Ni-NTA) prepared on a gold surface via a polyhistidine tag (Histag) as a linker molecule. We have further succeeded in the fabrication of PSII-gold nanoparticle multistructures on the surface of gold electrode, and significant enhancement of photocurrents was achieved due to increased number of immobilized PSII.     

Doping amount and temperature dependence of superplastic flow in tetragonal ZrO2 polycrystal doped with TiO2 and/or GeO2

The doping amount and temperature dependence of superplastic flow in a TiO₂- and/or GeO₂-doped tetragonal ZrO₂ polycrystal (TZP) were investigated in the doping range of 0.2–8 mol.% and in the temperature range of 1200–1550 °C. While the tensile ductility in the TZP is significantly improved by the co-doping of TiO₂ and GeO₂, there is an optimum combination of doping amount and temperature for enhancing the tensile ductility. The present study also shows that the flow stress decreases with an increase in the doping amount, but this decrease levels off with a 2–3 mol.% addition of GeO₂ or (TiO₂–GeO₂). The data for the flow behavior and thermal groove experiment indicated that TiO₂ and/or GeO₂ doping enhances the grain boundary diffusion of zirconium cations and reduces the grain boundary energy, respectively. These effects of grain boundary segregation can be regarded as the cause of the improved high-temperature ductility of (TiO₂–GeO₂)-doped TZP.     

Photo-sensor with photo-electric conversion molecules and a modified gold nanostructured FET gate film

We have investigated a nanostructured electrode from the viewpoint of improving the performance of FETs. The nanostructured gold layer acted as a positive factor contributing to an increase in the photocurrent, while maintaining low levels of photo-voltage (photo-V_oc) of the gold electrode itself and the FET performance (photo-I_ds). Such negative effects of the nanostructured gold layer were attributed to the low-surface coverage of molecules and high interactive ability between the electrode and the electro-active species in the enlarged diffusion layer of the electrolyte solution around the nanostructured gold electrode.     

Distribution of carbon contamination in MgAl2O4 spinel occurring during spark-plasma-sintering (SPS) processing: I – Effect of heating rate and post-annealing

Carbon contamination from the carbon paper/dies during spark-plasma-sintering (SPS) processing was examined in the MgAl₂O₄ spinel. The carbon contamination sensitively changes with the heating rate during the SPS processing. At the high heating rate of 100 °C/min, the carbon contamination having organized structures occurred over almost the entire area from the surface to deep inside the SPSed spinel disk. In contrast, at the slow heating rate of 10 °C/min, the carbon contamination having disordered structures occurred only around the surface area. The carbon phases transform into high pressure CO/CO₂ gases by post-annealing in air and lead to pore formation along the grain junctions. The pore formation significantly occurs at the high heating rate due to the large amount of the contaminant carbon phases. This suggests that if once the carbon contamination was formed in the materials, it is very difficult to remove the carbon phases from the materials.     

Resynthesis of reactive site peptide bond and temporary inhibition of Streptomyces metalloproteinase inhibitor

Streptomyces metalloproteinase inhibitor (SMPI) is a small proteinaceous inhibitor which inhibits metalloproteinases such as thermolysin (Ki =1.14 x 10(-10) M). When incubated with the enzyme, it is gradually hydrolyzed at the Cys64-Val65 peptide bond, which was identified as the reactive site by mutational analysis. To achieve a further understanding of the inhibition mechanism, we attempted to resynthesize the cleaved reactive site by using the enzyme catalytic action. The native inhibitor was resynthesized from the modified inhibitor (Ki =2.18 x 10(-8) M) by incubation with a catalytic amount of thermolysin under the same conditions as used for hydrolysis (pH 7.5, 25 degrees C), suggesting that SMPI follows the standard mechanism of inhibition of serine proteinase inhibitors. Temporary inhibition was observed when the native inhibitor and thermolysin were incubated at a 1:100 (mol/mol) enzyme-inhibitor ratio at 37 degrees C. SMPI showed temporary inhibition towards all the enzymes it inhibited. The inhibitory spectrum of SMPI was analyzed with various metalloproteinases based on the Ki values and limited proteolysis patterns. Pseudomonas elastase and Streptomyces griseus metalloproteinase II formed more stable complexes and showed much lower Ki values (approximately 2 pM) than thermolysin. In the limited proteolysis experiments weak inhibitors were degraded by the enzymes. SMPI did not inhibit almelysin, Streptomyces caespitosus neutral proteinase or matrix metalloproteinases. SMPI specifically inhibits metalloproteinases which are sensitive to phosphoramidon.