The molecular mechanism for carbon catabolite repression of the chitin response in Vibrio cholerae.

Vibrio cholerae is a facultative pathogen that primarily occupies marine environments. In this niche, V. cholerae commonly interacts with the chitinous shells of crustacean zooplankton. As a chitinolytic microbe, V. cholerae degrades insoluble chitin into soluble oligosaccharides. Chitin oligosaccharides serve as both a nutrient source and an environmental cue that induces a strong transcriptional response in V. cholerae. Namely, these oligosaccharides induce the chitin sensor, ChiS, to activate the genes required for chitin utilization and horizontal gene transfer by natural transformation. Thus, interactions with chitin impact the survival of V. cholerae in marine environments. Chitin is a complex carbon source for V. cholerae to degrade and consume, and the presence of more energetically favorable carbon sources can inhibit chitin utilization. This phenomenon, known as carbon catabolite repression (CCR), is mediated by the glucose-specific Enzyme IIA (EIIAGlc) of the phosphoenolpyruvate-dependent phosphotransferase system (PTS). In the presence of glucose, EIIAGlc becomes dephosphorylated, which inhibits ChiS transcriptional activity by an unknown mechanism. Here, we show that dephosphorylated EIIAGlc interacts with ChiS. We also isolate ChiS suppressor mutants that evade EIIAGlc-dependent repression and demonstrate that these alleles no longer interact with EIIAGlc. These findings suggest that EIIAGlc must interact with ChiS to exert its repressive effect. Importantly, the ChiS suppressor mutations we isolated also relieve repression of chitin utilization and natural transformation by EIIAGlc, suggesting that CCR of these behaviors is primarily regulated through ChiS. Together, our results reveal how nutrient conditions impact the fitness of an important human pathogen in its environmental reservoir

Digital Archive of the 17th century Mongolian Temple khiid

publisher奈良　モンゴル国では、数多くの重要な遺跡が残っているが、修復や保存がされているものは少なく、消失の危機にある遺跡もある。遺跡の現状を保存するためにデジタルアーカイブすることが急務である。本研究の目的は、これらの遺跡をデジタル化することであり、本稿では、17世紀にザナバザルによって建立された仏教寺院であるSardgiin　ｋhiidをデジタルアーカイブした方法について述べる。本研究では、３次元レーザー計測装置によるレーザ計測とドローン（小型無人飛行機）を利用した画像計測の２種類の方法を用いた。３次元レーザ計測装置は、精度の高い計測が可能であるが、広範囲を計測する場合には時間がかかる。一方で、ドローンを使って上空から遺跡を撮影し、画像計測をする場合には、３次元レーザ計測装置よりも精度は低いが、広範囲を短時間で計測することが可能である。計測した結果から、Sardgiin khiidの構造を明らかにした。さらに、構造をより明確に提示できるようにするために、3Dプリンタを利用してデジタル化したSardgiin　ｋhiidを、出力した結果について述べる

Leaflike structured multilayer assembly of dimercaptothiadiazole on gold surface

Adsorption of a heteroaromatic dithiol, 2,5-dimercapto-1,3,4-thiadiazole (DMT), on Au surface from a completely deaerated aqueous solution leads to the formation of a multilayer assembly via hydrogen bonding with water molecules, whereas adsorption from acetonitrile, ethanol, dimethyl sulfoxide, and chloroform solutions leads to the formation of a monolayer. Cyclic voltammetry (CV), attenuated total reflectance (ATR) infrared spectroscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were used to characterize the monolayer and multilayer assemblies of DMT on Au surface. Since DMT contains two S-H groups, it chemisorbs on Au surface through one of its two S-H groups, while the other S-H group is pointing away from the surface. The presence of free S-H groups on the Au surface was confirmed by CV, ATR-FT-IR, and XPS. It is presumed that the free S-H groups of DMT on the Au surface form a hydrogen bond with the water molecules. Subsequently, DMT molecules in solution form a hydrogen bond with the water molecules attached with DMT on Au surface, and this type of hydrogen bonding network goes on increasing when the soaking time of the Au surface in an aqueous solution of DMT increases. The involvement of water molecules in the multilayer formation was confirmed from the appearance of a broad stretching band around 3300 cm(-1) corresponding to the hydrogen bonded O-H in the ATR-FTIR spectrum, in addition to a binding energy peak at 533.4 eV due to hydrogen-donating water molecules in the O is region of XPS. The absence of a stretching band characteristic for S-S at 537 cm(-1) in the Raman spectrum confirmed that the multilayer assembly was not formed via S-S linkage. However, exposure of DMT multilayer to air shows a stretching band characteristic of S-S, indicating that aerial oxidation leads to the formation of S-S bond. SEM images show that DMT forms a leaflike structured multilayer assembly on Au surface