Inconsistent Structure and Motion of the Eastern Median Tectonic Line, Southwest Japan, during the Quaternary

The Median Tectonic Line (MTL) is the largest tectonic line in southwest Japan, and its eastern portion has moved as a right‐lateral fault with a reverse fault component during the Quaternary. Although a high dip of the MTL has been suggested from geomorphological studies, reflection surveys have indicated a low dip of 30–55°. Thus, the MTL shows contradiction between its fault dip and fault motion. In this study, we attempted to re‐estimate the dip of the MTL by gravity anomaly, gravity gradient tensor, and numerical simulation, restoring topographies caused by lateral faulting. The numerical simulations suggested that a fault dip of 70–75° is a reasonable dip of the MTL. These high‐dip faults are able to move as a lateral fault and have the possibility of reverse fault motion. Deformation patterns caused by faults with these dips are in harmony with the accumulated geological and geomorphological evidence for motions of the MTL. On the other hand, gravity and gravity gradient analyses showed only a material boundary with low dip. This suggested that the MTL does not have conspicuous density contrast at the boundary

Numerical Modeling

Numerical simulation to reproduce patterns of topography or subsurface structure is a useful technique for validating hypotheses regarding their forming processes and/or tectonics as their background. Here, the author describes an outline of dislocation modeling and several methods for applying it to reproduce topography or subsurface structure. Finally, it is reported that the formation processes of the Hohi Volcanic Zone proposed from geological viewpoints are validated by dislocation modeling

Characterization of catalytic α-1,3-glucanase isozymes from Paenibacillus glycanilyticus FH11 by using Brevibacillus system; Essential for suppression of Streptococcus mutans biofilms

S. mutans has been implicated in the etiology of dental caries by facilizing the colonization of tooth surfaces and playing a key role in the development of the virulent dental plaque. α-1,3-Glucan, which is a key structural constituent of the biofilm matrix (dental plaque), synthesized by glucosyltransferase type B (gtfB) in the presence of ingested sucrose. α-1,3-Glucanases also called mutanases, which hydrolyze α-1,3-glucan, are classified into two families of glycoside hydrolases, fungal (type 71) and bacterial (type 87). Because of being considered to degrade α-1,3-glucan, α-1,3-glucanases have been purified and characterized from various microbial sources. However, there are few reports on S. mutans biofilm study. For the host cell expression, Brevibacillus system is an effective bacterial expression system for secretory proteins. B. choshinensis is a gram-positive bacterium and easy to handle non-sporulating bacterium, lacking extracellular protease, that has been already shown to provide a high level of recombinant protein expression. Recently, many proteins are produced from this expression system and use for medical treatment, research study (1). Therefore, in this study we attempted to use Brevibacillus expression system to express, purify, and characterize of α-1,3- glucanase. In addition, we aimed to investigate the effect of recombinant enzyme on α-1,3-glucan biofilm produced by S. mutans from the viewpoints of formation and the effect of toothpaste agent on enzyme activity. Two novel catalytic domains of α-1,3-glucanase isozyme genes were cloned from P. glycanilyticus strain FH11 and heterologously expressed in Brevibacillus system. The recombinant isozymes, in termed CatAgl-FH1 and CatAgl-FH2, were purified to homogeneity with specific activity 0.70 U/mg and 0.77 U/mg respectively. The molecular mass of catalytic domain was estimated 62 kDa by SDS-PAGE. Both recombinant enzymes exhibited the different properties. The optimal pH of CatAgl-FH1 and CatAgl-FH2 were 5.5 and 6.0, respectively. The pH stability of CatAgl-FH1 and CatAgl-FH2 were in a range of pH 4.0-11.0 and 4.5-9.0, respectively. The optimal temperature of CatAgl-FH1 and CatAgl-FH2 were 60°C and 55°C, respectively and they were stable until 60°C. Thin Layer chromatography revealed their mode of hydrolysis towards α-1,3-glucan was endo-cleavage pattern. The major products of CatAgl-FH1 were di- and trisaccharide but mainly trisaccharide was for CatAgl-FH2. Both enzymes showed high tolerance against high concentration of sodium fluoride. However, each enzyme activity on surfactants were stepped down when sodium dodecyl sulfate and benzethonium concentration were increased. Please click Additional Files below to see the full abstract

Ultra-High-Resolution Seismic Surveys: 3D Sea Trial at Beppu Bay

A 3D high-resolution seismic (3D-HRS) survey was conducted to clearly reveal and map faults and fractures in a shallow-water region of Beppu Bay, Japan. The 3D-HRS was conducted using a dense array of six short streamer cables combined with a single GI gun, which generate the primary pulse and create the main bubble with generator and collapse the main bubble with injector. This high-frequency seismic source and high-density seismic source/receiver point distribution achieved a significant improvement in seismic imaging resolution. Because the 3D-HRS system is compact and lightweight and can be operated by small vessels, its effectiveness and necessity have been demonstrated, especially in shallow coastal waters, where conventional seismic survey using large ships and long streamer cables is difficult. For seismic data processing, pre-stack noise attenuation, de-ghosting, multiple removal, and acquisition footprint removal had essential roles in enhancing seismic imaging quality. Compared to existing 2D seismic survey technology, the 3D-HRS achieved much higher resolution and delineated highly detailed features of the seafloor and subsurface. Following the seismic processing sequence, similarity and thinned fault likelihood attribute workflows were applied to detect and visualize faults and fractures within the 3D-HRS volume. These seismic attributes revealed a network of broadly distributed faults and fractures along an active fault system in Beppu Bay