Utsunomiya University

About: Utsunomiya University is a education organization based out in Utsunomiya, Japan. It is known for research contribution in the topics: Laser & Holography. The organization has 4139 authors who have published 6812 publications receiving 91975 citations. The organization is also known as: Utsunomiya daigaku.

Degradation of N-Acylhomoserine Lactone Quorum Sensing Signaling Molecules by Potato Root Surface-Associated Chryseobacterium Strains

Abstract: N-Acylhomoserine lactones (AHLs) are used as quorum-sensing signaling molecules by many Gram-negative bacteria. Here, 413 bacterial strains were obtained from the roots of potato plants and screened for AHL-degrading bacteria using Chromobacterium violaceum reporter strains. Sixty one isolates degraded N-hexanoyl-L-homoserine lactone (C6-HSL) within 24 h. Based on their 16S rRNA gene sequences, most of these isolates were assigned to the genus Chryseobacterium and divided into eight groups. Most of the strains degraded N-decanoyl-L-homoserine lactone (C10-HSL) and were active against 3-oxo-substituted AHLs. Groups V and VI were more effective at inactivating AHLs. One group V strain, StRB402, showed putative AHL-lactonase activity. This is the first report of AHL-degrading Chryseobacterium strains.

Variations in Plasma Melatonin Levels of the Rainbow Trout (Oncorhynchus mykiss) under Various Light and Temperature Conditions

Abstract: Daily variations in plasma melatonin levels in the rainbow trout Oncorhynchus mykiss were studied under various light and temperature conditions. Plasma melatonin levels were higher at mid-dark than those at mid-light under light-dark (LD) cycles. An acute exposure to darkness (2 hr) during the light phase significantly elevated the plasma melatonin to the level that is comparable with those at mid-dark, while an acute exposure to a light pulse (2 hr) during the dark phase significantly suppressed melatonin to the level that is comparable with those at mid-light. Plasma melatonin kept constantly high and low levels under constant darkness and constant light, respectively. No circadian rhythm was seen under both conditions. When the fish were subjected to simulative seasonal conditions (simulative (S)-spring: under LD 13.1:10.9 at 13 degrees C; S-summer: under LD 14.3:9.7 at 16.5 degrees C; S-autumn: under LD 11.3:12.7 at 13 degrees C; S-winter: under LD 10.1:13.9 at 9 degrees C), melatonin levels during the dark phase were significantly higher than those during the light phase irrespective of simulative seasons. The peak melatonin level in each simulative season significantly correlated with temperature but not with the length of the dark phase employed. In addition, the peak melatonin level in S-autumn was significantly higher than those in S-spring although water temperature was the same under these conditions. These results indicate that the melatonin rhythm in the trout plasma is not regulated by an endogenous circadian clock but by combination of photoperiod and water temperature.

Production and Degradation of N-Acylhomoserine Lactone Quorum Sensing Signal Molecules in Bacteria Isolated from Activated Sludge

Abstract: N-Acylhomoserine lactones (AHLs) function as quorum-sensing signaling molecules in many Gram-negative bacteria We isolated a total of 672 bacterial strains from activated sludge obtained from seven sewage treatment plants in Tochigi Prefecture, Japan, and screened for AHL-producing and degrading strains Isolates (n = 107) stimulated AHL-mediated purple pigment production in AHL reporter strains Chromobacterium violaceum CV026 and VIR07 Based on their 16S rRNA gene sequences, most of these AHL-producing isolates were assigned to the genus Aeromonas, and they were divided into six groups Isolates (n = 46) degraded N-decanoyl-L-homoserine lactone (C10-HSL) within 24 h Based on their 16S rRNA gene sequences, the most dominant AHL-degrading isolates were assigned to the genus Acinetobacter and divided into six groups Strains Ooi24, Omo91, and Uzu81, which showed higher C10-HSL-degrading activity, showed putative AHL-acylase activity

New Types of Anodes for the Oxygen Evolution Reaction in Acidic Solution

Abstract: New type of electrodes of IrO/sub 2//TiO/sub 2//Ti, where the TiO/sub 2/ films are prepared by the anodic oxidation accompanied by sparking and are porous, were tested as the anode for the oxygen evolution reaction in acidic solution. The IrO/sub 2//TiO/sub 2//Ti electrodes were prepared by thermal decomposition of IrCl/sub 4/ aqueous solution on the TiO/sub 2/ films. The resistivities of the electrodes themselves became zero by the thermal decomposition process to form IrO/sub 2/, if the TiO/sub 2/ films were prepared by the anodic oxidation accompanied by sufficient sparking. It was found that the catalytic activities of the IrO/sub 2//TiO/sub 2//Ti electrodes are higher than that of the IrO/sub 2//Ti electrode. The electrodes prepared at a calcination temperature lower than about 500/sup 0/C dissolved in the long-term test, although their surface areas were very large. The IrO/sub 2//TiO/sub 2//Ti electrodes prepared at 550/sup 0/ are very superior in their catalytic activity and their stability in the long-term test for the oxygen evolution reaction. The surface difference between the IRO/sub 2//TiO/sub 2//Ti and the IrO/sub 2//Ti electrodes is also discussed.