Coaggregation between Prevotella oris and Porphyromonas gingivalis

Background/PurposeThe coaggregation of bacteria has been defined as one of the most important processes in the oral infection such as periodontitis. Prevotella oris and Porphyromonas gingivalis, which are two of the periodontopathogens, are frequently detected in severe forms of periodontal diseases. However, the interaction between P. oris and P. gingivalis is still unknown. In this study, the coaggregation of P. oris with nine oral bacterial species including P. gingivalis was examined.MethodsAll bacteria used in this study were cultured anaerobically and suspended in coaggregation buffer. Each cell suspension was mixed in a test tube and subjected to shaking at room temperature for 1 hour. Subsequently, the coaggregation values were scored. Furthermore, the effects of various chemical reagents, and heat, proteinase K, and serum treatment were examined.ResultsIn this study, P. oris coaggregated only with P. gingivalis. A heat-stable, nonproteinous component of P. oris and a heat-labile, proteinous component of P. gingivalis play important roles in this coaggregation. In addition, this coaggregation was inhibited by l-arginine, l-lysine, and Nα-p-tosyl-l-lysine. Therefore, it was considered that a cell surface protein on P. gingivalis, such as gingipain, may be involved in the coaggregation. Furthermore, the coaggregation was not inhibited by serum treatment.ConclusionThis is the first report to describe the coaggregation of P. oris and P. gingivalis. Our study proposes the possibility that P. oris may promote the colonization of P. gingivalis in an early stage of biofilm formation. Furthermore, this coaggregation may contribute to the initiation and progression of periodontitis

Purification and characterization of hemolysin from Prevotella oris

AbstractWe observed hemolytic activity in culture supernatant of Prevotella oris. Results from growth-phase experiments show that hemolysin production increased during the logarithmic growth phase and decreased during the stationary phase. The hemolysin produced by P. oris was purified from the culture supernatant by ultrafiltration, diethylaminoethyl (DEAE) and carboxymethyl (CM) ion-exchange chromatography, and gel filtration chromatography; further, we investigated the purified hemolysin characteristics, including its ability to lyse human, horse, sheep, and rabbit erythrocytes. The purified hemolysin was observed as a single, 16-kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel. The specific activity was obtained by concentrating the purified hemolysin by 9200 fold. Although hemolysin was inactivated by heat treatment, ethylenediaminetetraacetic acid (EDTA), l-cysteine, dithiothreitol (DTT), and 2-mercaptoethanol enhanced its activity. Further, treatments using trypsin, MgCl2, CaCl2, and cholesterol did not affect its hemolytic activity. A pH of 6.0 was optimal for inducing the hemolysin activity. To the best of our knowledge, this is the first report describing the purification and characterization of hemolysin produced by P. oris

Prevotella oris溶血素の特徴とその赤血球膜との相互作用(The characteristics of Prevotella oris hemolysin and its interaction with the erythrocyte membrane)

P.orisはSDSポリアクリルアミドゲル電気泳動(SDS-PAGE)上で16kDaバンドとして観察される蛋白質溶血素を産生する。P.oris溶血素のN末端アミノ酸配列を分析した。7N末端アミノ酸を特定し、P.oris溶血素が短鎖ペプチド配列を有すると推定した。溶血素のアミノ酸配列は他の細菌性蛋白やペプチドと共通の配列ではなかった。P.oris溶血素は溶血前に温度依存性に赤血球と結合することが明らかになった。この溶血活性は赤血球をトリプシンまたはグリコシダーゼで処理した場合に阻害された。コレステロールは活性には影響しなかった。トリプシン処理した赤血球膜の特徴からSDS-PAGEにおいて46kDa糖蛋白が消失した。以上より、46kDa赤血球膜糖蛋白は溶血素の結合部位であることが示唆された。本研究はP.oris溶血素のN末端アミノ酸配列とその赤血球膜上の結合部位に関する初めての報告である。P.orisはSDSポリアクリルアミドゲル電気泳動(SDS-PAGE)上で16kDaバンドとして観察される蛋白質溶血素を産生する。P.oris溶血素のN末端アミノ酸配列を分析した。7N末端アミノ酸を特定し、P.oris溶血素が短鎖ペプチド配列を有すると推定した。溶血素のアミノ酸配列は他の細菌性蛋白やペプチドと共通の配列ではなかった。P.oris溶血素は溶血前に温度依存性に赤血球と結合することが明らかになった。この溶血活性は赤血球をトリプシンまたはグリコシダーゼで処理した場合に阻害された。コレステロールは活性には影響しなかった。トリプシン処理した赤血球膜の特徴からSDS-PAGEにおいて46kDa糖蛋白が消失した。以上より、46kDa赤血球膜糖蛋白は溶血素の結合部位であることが示唆された。本研究はP.oris溶血素のN末端アミノ酸配列とその赤血球膜上の結合部位に関する初めての報告である

Bayesian posterior approximation via greedy particle optimization

In Bayesian inference, the posterior distributions are difficult to obtain analytically for complex models such as neural networks. Variational inference usually uses a parametric distribution for approximation, from which we can easily draw samples. Recently discrete approximation by particles has attracted attention because of its high expression ability. An example is Stein variational gradient descent (SVGD), which iteratively optimizes particles. Although SVGD has been shown to be computationally efficient empirically, its theoretical properties have not been clarified yet and no finite sample bound of the convergence rate is known. Another example is the Stein points (SP) method, which minimizes kernelized Stein discrepancy directly. Although a finite sample bound is assured theoretically, SP is computationally inefficient empirically, especially in high-dimensional problems. In this paper, we propose a novel method named maximum mean discrepancy minimization by the Frank-Wolfe algorithm (MMD-FW), which minimizes MMD in a greedy way by the FW algorithm. Our method is computationally efficient empirically and we show that its finite sample convergence bound is in a linear order in finite dimensions

Large Faraday effect of borate glasses with high Tb³⁺ content prepared by containerless processing

Borate glasses containing a large amount of Tb³⁺ ions have been prepared by containerless processing. The content of Tb₂O₃ reached 60 mol%. The glass bearing the highest content of Tb³⁺ ions showed a large Faraday effect; the Verdet constant was 234 rad/T m. Annealing of the glasses in H₂/N₂ atmosphere resulted in a low optical absorption coefficient, leading to an extremely large magneto-optical figure of merit that was ∼1.7 times higher than that of Tb₃Ga₅O₁₂ single crystal