Hypoxic condition-selective upconversion via triplet–triplet annihilation based on POSS-core dendrimer complexes

The influence on the efficiencies of the triplet–triplet annihilation (TTA)-supported upconversion by oxygen under biomimetic conditions was investigated. From the solution containing the dendrimer complexes based on polyhedral oligomeric silsesquioxane (POSS)-core dendrimer with the Pt complex of octaethylporphyrin (PtOEP) and anthracene in PBS, the fluorescence emission of anthracene depending on the dissolved oxygen (DO) concentrations via the TTA-supported upconversion was obtained with the excitation light at 540 nm. In particular, we observed strong emission only under hypoxic conditions. In addition, it was found that the emission intensity via TTA-supported upconversion can be reversibly regulated by the DO concentrations in the solution.     

Effect of interrupted eruption on the enamel organ of the rat incisor

The aim of this study was to investigate the behavior of rat incisor tissues during the inhibition of tooth eruption. Twenty Sprague-Dawley rats were used in this study, and incisor eruption was inhibited by a screw pin. Animals were sacrificed 1, 3, 7 and 14 days after the start of the experiment. Cross-sections at the mesial point of the mandibular first molar and sagittal sections of the mandibular tooth germ area were examined using immunohistochemical and immunofluorescence methods. For morphometric analysis, numbers of TRAP-positive cells were calculated against the total number of cells. In cross-sections from the experimental group, dentin was thickened and pulp tissue was constricted day by day. On days 1, 3 and 7, nestin-positive cells were observed in all odontoblast cell bodies and processes, while on day 14 fewer nestin-positive cells were seen than in the control group. On day 14, the mesial area of the periodontal ligament was constricted and the number of TRAP-positive cells in the mesial area was significantly higher than in the control group. In sagittal sections, enamel formation was found to be increased on days 7 and 14. Furthermore, in the enamel matrix amelogenin was expressed more strongly than in the control group. PCNA-positive cells were significantly increased in cells of the tooth germ compared with the control group. These results suggest that inhibition of tooth eruption accelerates the apical elongation with resorption of the mesial area of the alveolar bone and stimulates cell proliferation with thickened enamel towards the apical end.     

Isolation and Structure Elucidation of Three New Insecticidal Cyclodepsipeptides,Destruxins C and D and Desmethyldestruxin B,Produced by Metarrhizium anisopliae

A multi-channel continuous-flow analyzer equipped with biosensing devices was developed for multi-component measurement and its use in automating routine analysis was evaluated.

Biosensing was achieved by the aid of an immobilized enzyme reactor installed in the channel, and the channel switching process for the sensing of a different compound was made by using a column-switching rotary valve. Another rotary valve was used for auto-sampling. Both of the two rotary valves were interfaced to a system controller and work conjugatively in a programmed manner. Signal subtraction between different channels was found to be more precise compared with the multi-channel flow-injection analysis method, which is of merit for an analysis utilizing enzyme relay reaction (as for sucrose analysis) or for background signal subtraction. Glucose, lactate, and sucrose content in real samples were measured automatically with high reproducibility, and the results agree well with the kit method.     

Properties of the Crystalline Quinolinate Phosphoribosyltransferase from Hog Liver

Quinolinate phosphoribosyltransferase has an important role in the NAD de novo biosynthetic pathway. Crystalline quinolinate phosphoribosyltransferase could be obtained for the first time from mammalian tissue. The crystalline enzyme preparation was certified to be homogeneous by polyacrylamide gel disc electrophoresis. Catalytic properties of this enzyme preparation were investigated. Optimum pH for the reaction was 6.1. Divalent cations were absolutely required and Mg²⁺ was the most effective. Michaelis constants for quinolinic acid and PRPP were 1.2 × 10^?4 m and 1.8 × 10^?4 m, respectively. Quinolinic acid could not be replaced by nicotinic acid or 2-amino nicotinic acid in this reaction. Di- and tri-valent cations fairly inhibited the reaction, but mono-valent cations had no effects. The reaction product was identified as β-nicotinic acid mononucleotide by its ultraviolet absorption spectra, paper chromatography, paper electrophoresis and its ORD spectrum.     

Comparison of Extracellular Polysaccharide Produced by Pullularia pullulans with Polysaccharides in the Cells and Cell Wall

The purified swep hydrolase appeared homogeneous on SDS disc electrophoresis, and the molecular weights of the enzyme and the subunit were 280,000 and 70,000, respectively. The isoelectric point of this enzyme was pH 4.8.     

Structural Uniformity of Pullulan Produced by Several Strains of Pullularia pullulans

Extracellular polysaccharides produced by 3 strains of Pullularia pullulans were fractionated by treating with cetyl trimethyl ammonium hydroxide into soluble and insoluble fractions, and the structure of the former fraction, i.e., pullulan, was studied. The yield and the ratio of 2 fractions varied widely according to the strains. But the structure of pullulan was found to be uniform irrespective of the strains used. All 3 samples of pullulan gave only glucose on complete acid hydrolysis, and 93~95% maltotriose and 5~7% maltotetraose after isoamylase (pullulanase) action. The ratio of α-1,4- to α-1,6-glucosidic linkages calculated from periodate oxidation data coincided very well with the value expected from the ratio of maltotriose to maltotetraose units. An evidence for the complete absence of branch structure in pullulan was presented from the results of hydrolysis by pullulan 4-glucanohydrolase.     

Functional and Structural Analysis of a β-Glucosidase Involved in β-1,2-Glucan Metabolism in Listeria innocua

Despite the presence of β-1,2-glucan in nature, few β-1,2-glucan degrading enzymes have been reported to date. Recently, the Lin1839 protein from Listeria innocua was identified as a 1,2-β-oligoglucan phosphorylase. Since the adjacent lin1840 gene in the gene cluster encodes a putative glycoside hydrolase family 3 β-glucosidase, we hypothesized that Lin1840 is also involved in β-1,2-glucan dissimilation. Here we report the functional and structural analysis of Lin1840. A recombinant Lin1840 protein (Lin1840r) showed the highest hydrolytic activity toward sophorose (Glc-β-1,2-Glc) among β-1,2-glucooligosaccharides, suggesting that Lin1840 is a β-glucosidase involved in sophorose degradation. The enzyme also rapidly hydrolyzed laminaribiose (β-1,3), but not cellobiose (β-1,4) or gentiobiose (β-1,6) among β-linked gluco-disaccharides. We determined the crystal structures of Lin1840r in complexes with sophorose and laminaribiose as productive binding forms. In these structures, Arg572 forms many hydrogen bonds with sophorose and laminaribiose at subsite +1, which seems to be a key factor for substrate selectivity. The opposite side of subsite +1 from Arg572 is connected to a large empty space appearing to be subsite +2 for the binding of sophorotriose (Glc-β-1,2-Glc-β-1,2-Glc) in spite of the higher K_m value for sophorotriose than that for sophorose. The conformations of sophorose and laminaribiose are almost the same on the Arg572 side but differ on the subsite +2 side that provides no interaction with a substrate. Therefore, Lin1840r is unable to distinguish between sophorose and laminaribiose as substrates. These results provide the first mechanistic insights into β-1,2-glucooligosaccharide recognition by β-glucosidase.     

Summed Probability Distribution of 14C Dates Suggests Regional Divergences in the Population Dynamics of the Jomon Period in Eastern Japan

Recent advances in the use of summed probability distribution (SPD) of calibrated ¹⁴C dates have opened new possibilities for studying prehistoric demography. The degree of correlation between climate change and population dynamics can now be accurately quantified, and divergences in the demographic history of distinct geographic areas can be statistically assessed. Here we contribute to this research agenda by reconstructing the prehistoric population change of Jomon hunter-gatherers between 7,000 and 3,000 cal BP. We collected 1,433 ¹⁴C dates from three different regions in Eastern Japan (Kanto, Aomori and Hokkaido) and established that the observed fluctuations in the SPDs were statistically significant. We also introduced a new non-parametric permutation test for comparing multiple sets of SPDs that highlights point of divergences in the population history of different geographic regions. Our analyses indicate a general rise-and-fall pattern shared by the three regions but also some key regional differences during the 6^th millennium cal BP. The results confirm some of the patterns suggested by previous archaeological studies based on house and site counts but offer statistical significance and an absolute chronological framework that will enable future studies aiming to establish potential correlation with climatic changes.