The DNA methylation inhibitor 5-aza-2’-deoxycytidine retards cell growth and alters gene expression in canine mammary gland tumor cells

Disruption of gene expression by DNA methylation changes is widely involved in tumorigenesis. Here,to investigate DNA methylation changes in canine, we treated a canine mammary gland tumor cell line with a DNA methylation inhibitor, 5-aza-2’-deoxycytidine (5-aza). Cell growth was significantly retarded following 5-aza treatment and the epithelial marker genes CDH1 and KRT18 were significantly up-regulated, whereas the mesenchymal marker genes CDH2 and VIM were significantly downregulated. We also found a significant decrease in DNA methylation level in the CDH1 promoter region by 5-aza treatment. These results showed for the first time in canine mammary gland tumor cells that inhibition of DNA methylation caused cell growth retardation and affected epithelial mesenchymal transition-related gene expression via changes in DNA methylation level

Element Material Exposure Experiment by EFFU

The National Space Development Agency of Japan (NASDA) is planning to perform an 'Element Material Exposure Experiment' using the Exposed Facility Flyer Unit (EFFU). This paper presents an initial design of experiments proposed for this project by our company. The EFFU is installed on the Space Flyer Unit (SFU) as a partial model of the Space Station JEM exposed facility. The SFU is scheduled to be launched by H-2 rocket in January or February of 1994, then various tests will be performed for three months, on orbit of 500 km altitude, and it will be retrieved by the U.S. Space Shuttle and returned to the ground. The mission sequence is shown

Optically Induced Rotation of Microcylinders Made of Photopolymerizable Nematic Liquid Crystal

We report for the first time the use of photopolymerizable liquid crystals in fabricating microsized cylinders that are rotated by a circularly polarized laser beam. They were fabricated by two-photon photopolymerization from liquid crystals whose molecules had been deliberately oriented on a rubbed surface. The rotational torque showed similar oscillatory structures to those observed in the intensity of light transmitted through crossed Nikols as a function of cylinder height. From the structures, the birefringence of the cylinders was estimated and the main mechanism underlying the rotational torque transfer was determined

Puzzles in the Forex Tokyo “Fixing”: Order Imbalances and Biased Pricing by Banks

“Fixing” in the foreign exchange market is a market practice that determines the bid-ask-mid- point exchange rate at a scheduled time, 10am in Tokyo and 4pm in London. The fixing exchange rate is then applied to the settlement of foreign exchange transactions between banks and retail customers including broker dealers, institutional investors, insurance companies, exporters, and importers, with varying bid-ask spreads. Our findings for the Tokyo fixing are summarized as follows: (1) Price spikes in the Tokyo fixing are more frequent than in the London fixing. (2) The customer orders are biased toward buying foreign currencies, which is predictable. (3) Before 2008, the fixing prices set by banks were biased upward, and higher than the highest transaction price during the fixing time window. (4) Even after 2008, the fixing prices announced by banks were still above the median transaction price during the fixing window, suggesting that banks make predictable profits. (5) The calendar effects also matter for determination of the fixing rate and the price fluctuation around fixing time

Was the Forex Fixing Fixed?

“Fixing” of the exchange rate (price) is a rule among the Forex market participating institutions to set a reference/settlement price for the day. Major fixings occur at 9:55 am Tokyo time for transactions between Japanese banks and their customers, and at 4:00 pm London time for transactions between European and US banks and their customers. The two fixings have different regulations and institutions. The London fix is calculated as an average price during the one minute window around 4:00 pm. We empirically examine the movement of prices around the time of fixing. Regulators in the UK and the US have accused banks of colluding by manipulating the price around the London fixing time. It has been mentioned in the media that there was evidence of “chats” among traders of different institutions in order to carry out this collusion. But, is there evidence of price manipulation? We found little evidence of volatile movement (or spikes) in prices around the fixing time. In fact, liquidity provision at the fixing time is larger than other times, which makes the price impact of any trade smaller. At the Tokyo fixing, however, financial institutions can fix the price by themselves based on the market price. Although the market provides deep liquidity at the Tokyo fixing as well, such financial institutions had announced prices to be more favorable for banks up until 2008. Such deviation of the fixing price from the market price might be related to the settlement needs of importers, as well as banks wanting to reduce the risk of being caught with a dollar shortage later in the day

Isolation and Cs+ resistance mechanism of Escherichia coli strain ZX-1

This research aims to elucidate the physiological mechanisms behind the accidental acquisition of high-concentration cesium ions (Cs+) tolerance of Escherichia coli and apply this understanding to develop bioremediation technologies. Bacterial Cs+ resistance has attracted attention, but its physiological mechanism remains largely unknown and poorly understood. In a prior study, we identified the Cs+/H+ antiporter TS_CshA in Microbacterium sp. TS-1, resistant to high Cs+ concentrations, exhibits a low Cs+ affinity with a Km value of 370 mM at pH 8.5. To enhance bioremediation efficacy, we conducted random mutagenesis of TS_cshA using Error-Prone PCR, aiming for higher-affinity mutants. The mutations were inserted downstream of the PBAD promoter in the pBAD24 vector, creating a mutant library. This was then transformed into E. coli-competent cells. As a result, we obtained a Cs+-resistant strain, ZX-1, capable of thriving in 400 mM CsCl—a concentration too high for ordinary E. coli. Unlike the parent strain Mach1™, which struggled in 300 mM CsCl, ZX-1 showed robust growth even in 700 mM CsCl. After 700 mM CsCl treatment, the 70S ribosome of Mach1™ collapsed, whereas ZX-1 and its derivative ΔZX-1/pBR322ΔAp remained stable. This means that the ribosomes of ZX-1 are more stable to high Cs+. The inverted membrane vesicles from strain ZX-1 showed an apparent Km value of 28.7 mM (pH 8.5) for Cs+/H+ antiport activity, indicating an approximately 12.9-fold increase in Cs+ affinity. Remarkably, the entire plasmid isolated from ZX-1, including the TS_cshA region, was mutation-free. Subsequent whole-genome analysis of ZX-1 identified multiple SNPs on the chromosome that differed from those in the parent strain. No mutations in transporter-related genes were identified in ZX-1. However, three mutations emerged as significant: genes encoding the ribosomal bS6 modification enzyme RimK, the phage lysis regulatory protein LysB, and the flagellar base component protein FlgG. These mutations are hypothesized to affect post-translational modifications, influencing the Km value of TS_CshA and accessory protein expression. This study unveils a novel Cs+ resistance mechanism in ZX-1, enhancing our understanding of Cs+ resistance and paving the way for developing technology to recover radioactive Cs+ from water using TS_CshA-expressing inverted membrane vesicles

Coupling between pore formation and phase separation in charged lipid membranes

We investigated the effect of charge on the membrane morphology of giant unilamellar vesicles (GUVs) composed of various mixtures containing charged lipids. We observed the membrane morphologies by fluorescent and confocal laser microscopy in lipid mixtures consisting of a neutral unsaturated lipid [dioleoylphosphatidylcholine (DOPC)], a neutral saturated lipid [dipalmitoylphosphatidylcholine (DPPC)], a charged unsaturated lipid [dioleoylphosphatidylglycerol (DOPG$^{\scriptsize{(-)}}$)], a charged saturated lipid [dipalmitoylphosphatidylglycerol (DPPG$^{\scriptsize{(-)}}$)], and cholesterol (Chol). In binary mixtures of neutral DOPC/DPPC and charged DOPC/DPPG$^{\scriptsize{(-)}}$, spherical vesicles were formed. On the other hand, pore formation was often observed with GUVs consisting of DOPG$^{\scriptsize{(-)}}$ and DPPC. In a DPPC/DPPG$^{\scriptsize{(-)}}$/Chol ternary mixture, pore-formed vesicles were also frequently observed. The percentage of pore-formed vesicles increased with the DPPG$^{\scriptsize{(-)}}$ concentration. Moreover, when the head group charges of charged lipids were screened by the addition of salt, pore-formed vesicles were suppressed in both the binary and ternary charged lipid mixtures. We discuss the mechanisms of pore formation in charged lipid mixtures and the relationship between phase separation and the membrane morphology. Finally, we reproduce the results seen in experimental systems by using coarse-grained molecular dynamics simulations.Comment: 34 pages, 10 figure

関西大学での思い出

伊藤誠宏教授退職記念