Ethanol-tolerant Saccharomyces cerevisiae strains isolated under selective conditions by over-expression of a proofreading-deficient DNA polymerase δ

Ethanol damages the cell membrane and functional proteins, gradually reducing cell viability, and leading to cell death during fermentation which impairs effective bioethanol production by budding yeast Saccharomyces cerevisiae. To obtain more suitable strains for bioethanol production and to gain a better understanding of ethanol tolerance, ethanol-tolerant mutants were isolated using the novel mutagenesis technique based on the disparity theory of evolution. According to this theory evolution can be accelerated by affecting the lagging-strand synthesis in which DNA polymerase δ is involved. Expression of the pol3-01 gene, a proofreading-deficient of DNA polymerase δ, in S. cerevisiae W303-1A grown under conditions of increasing ethanol concentration resulted in three ethanol-tolerant mutants (YFY1, YFY2 and YFY3), which could grow in medium containing 13% ethanol. Ethanol productivity also increased in YFY strains compared to the wild-type strain in medium containing 25% glucose. Cell morphology of YFY strain cells was normal even in the presence of 8% ethanol, whereas W303-1A cells were expanded by a big vacuole. Furthermore, two of these mutants were also resistant to high-temperature, Calcofluor white and NaCl. Expression levels of TPS1 and TSL1, which are responsible for trehalose biosynthesis, were higher in YFY strains relative to W303-1A, resulting in high levels of intracellular trehalose in YFY strains. This contributed to the multiple-stress tolerance that makes YFY strains suitable for the production of bioethanol.     

Microscopic observations and inflammatory cytokine productions of human macrophage phagocytising submicron titanium particles

This study was performed to microscopically observe and measure inflammatory cytokine production by human macrophages phagocytosing submicron titanium (Ti) particles. Observations with secondary electron microscopy (SEM), SEM/electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) indicated that macrophages [phorbol-12-myristate-13-acetate (PMA)-differentiated THP-1 cells] at 24 h in culture actively phagocytosed and accumulated submicron Ti particles in intracellular phagosomes, in which refinement of Ti particles occurred. The macrophages were also cultured for 24 h in four media with and without submicron Ti particles and lipopolysaccharide (LPS; components of bacteria). Whilst neither stimulus reduced cell viability, submicron Ti particles and LPS activation independently and synergistically caused the macrophages to produce three inflammatory cytokines (TNF-α, IL-1β and IL-6) at high levels in the culture supernatants. The inflammatory and osteolysis conditions caused by macrophages phagocytosing submicron Ti particles would be worsened by challenge with LPS in patients wearing Ti prostheses.     

Multiple scattering effects of MeV electrons in very thick amorphous specimens

Multiple scattering has an important influence on the analysis of microns-thick specimens with MeV electrons. In this paper, we report on effects of multiple scattering of MeV electrons on electron transmission and imaging of tilted and thick amorphous film specimens by experiment and theoretical analysis. Electron transmission for microns-thick epoxy-resin and SiO₂ specimens calculated by the multiple elastic-scattering theory is in good agreement with measurements in the ultrahigh voltage electron microscope (ultra-HVEM) at Osaka University. Electron transmission and electron energy are then presented in an approximate power law. The bright-field ultra-HVEM images of gold particles on the top or bottom surfaces of 5 and 15 μm thick specimens further illustrate the effect of multiple scattering on image quality. The observed top‐bottom effect for the very thick specimens appears to be mainly caused by multiple elastic scattering. With increase in the accelerating voltage from 1 to 2 MV, image blurring, contrast, the signal-to-noise ratio, and the top‐bottom effect are improved because of reduction in the influence of multiple scattering. However, the effect of specimen thickness on image blurring is shown to be stronger than that of accelerating voltage. At the 2 MV accelerating voltage, the 100 nm gold particle can be imaged with less blurring of ∼4 nm when located at the bottom surface of a 15 μm thick epoxy-resin specimen.     

Synthesis of methyl boron nitride film as low-k insulating film for LSI interconnection

Low dielectric constant (k) materials for the ULSI interconnect insulator are required to meet the fast development of high-speed devices. We have investigated low-k material of boron nitride containing methyl (methyl boron nitride) by using tris-di-methyl-amino-boron (TMAB) gas. The dielectric constant (k) of the film decreases with decreasing RF plasma power and the k value of the methyl BN film can be achieved as low as 1.8 at 10 W RF plasma power.Absorption band of the film was observed at 2960 cm^? 1 due to unsymmetrical stretching mode of C–H in CH₃. It is thought that increasing C–H bond with low polarizability and reducing CN bond with high polarizability can realize a lower k value. The film has also high resistivity of more than 1 × 10⁹ Ω cm and sufficient Young modulus of more than 26 GPa for the interlayer of LSI interconnection. There is a possibility that the dielectric constant can be decreased keeping the BN structure with high strength. The methyl BN film is an extremely attractive material as low-k material of next generation devices.     

Coupling simulation system of annual building energy and microclimate

We have developed a simulation system for a year-round assessment of environmental comfort, energy conservation, and CO₂ emissions in buildings and street blocks where active utilization of sunshine, vegetation and solar energy resources is fully considered. An analysis model has been constructed for handling interactions between highly complex street-block wide solar radiation patterns and building air-conditioning load. As a demonstration case of the present system, coupled solar radiation-thermal load analysis for an eleven-story office building has been performed. By comparing the result of a building located in a city block with a reference case of a self-standing building, the proper arrangement of buildings and spaces such as solar reflectance of building surface may be proposed.     

The molecular origin of enhanced toughness in double-network hydrogels: A neutron scattering study

Double-network hydrogels (DN-gels) are a new class of crosslinked polymer networks with extraordinary mechanical properties while containing 80–90 vol.% water. Small-angle neutron scattering (SANS) was applied to investigate the molecular origin of the mechanical properties observed in DN-gels. We present SANS results in both deformed and undeformed conditions for a tough DN-gel made of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) and polyacrylamide (PAAm). The SANS measurements indicate that deformation of DN-gels results in periodic and mesoscale (1.5 μm) compositional fluctuations in both PAMPS and PAAm. In addition, SANS measurements also indicate that the DN-gel constituents interact favorably with each other while in water. This favorable interaction between PAMPS and PAAm is consistent with the rheological results on solution mixtures of these two polymers. The implications of the above observations to toughening mechanisms are discussed.     

Renal ischemia/reperfusion remotely improves myocardial energy metabolism during myocardial ischemia via adenosine receptors in rabbits: effects of "remote preconditioning"

OBJECTIVES: This study examined the changes in myocardial energy metabolism during myocardial ischemia after "remote preconditioning" and investigated the involvement of adenosine receptors in the mechanisms of this effect. BACKGROUND: Recent studies have indicated that a brief period of ischemia and reperfusion (ischemic preconditioning, PC) in a remote organ reduces myocardial infarct size (IS) protecting against subsequent sustained myocardial ischemia. However, the mechanisms of "remote PC" remain unclear. We assessed myocardial energy metabolism during sustained myocardial ischemia and reperfusion after renal PC (RPC), in comparison with that after myocardial PC (MPC) in open-chest rabbits. It has been established that adenosine receptors are involved in the mechanisms of MPC. METHODS: Rabbits that had been anesthetized with halothane were divided into six groups. The control (CNT) group underwent 40-min coronary occlusion followed by 120 min reperfusion. Before the procedure, the MPC group underwent an additional protocol of 5 min coronary artery occlusion and 20 min reperfusion, and the RPC group received a 10 min episode of renal artery occlusion and 20 min reperfusion. In additional experimental groups, 8 sulfophenyl-theophylline (SPT, 10 mg/kg), an adenosine receptor inhibitor, was intravenously injected before the 40 min myocardial ischemia (SPT, MPC + SPT and RPC + SPT groups, respectively). Myocardial levels of phosphocreatine (PCr), ATP and intracellular pH (pHi) were measured by 31P-NMR spectroscopy. RESULTS: RPC and MPC delayed the decreases in ATP levels, preserved pHi during 40-min myocardial ischemia and resulted in better recovery of ATP and PCr during 120 min reperfusion compared with the controls. SPT abolished the improvement in myocardial energy metabolism and the reduction in myocardial IS caused by MPC or RPC. Myocardial IS in the CNT (n = 8), MPC (n = 9), RPC (n = 9), SPT (n = 6), MPC + SPT (n = 8) and RPC + SPT (n = 8) groups averaged 42.8+/-3.5%, 18.2+/-1.8%*, 19.6+/-1.3%*, 44.9+/-5.0%, 35.6+/-2.7% and 34.8+/-3.6% of the area at risk (*p < 0.05 vs. CNT), respectively. CONCLUSIONS: PC in a remote organ, similar to MPC, improved myocardial energy metabolism during ischemia and reperfusion and reduced IS in vivo by an adenosine-dependent mechanism in rabbits.     

Fast surface profiler by white-light interferometry by use of a new algorithm based on sampling theory

We propose a fast surface-profiling algorithm based on white-light interferometry by use of sampling theory. We first provide a generalized sampling theorem that reconstructs the squared-envelope function of the white-light interferogram from sampled values of the interferogram and then propose the new algorithm based on the theorem. The algorithm extends the sampling interval to 1.425 microm when an optical filter with a center wavelength of 600 nm and a bandwidth of 60 nm is used. The sampling interval is 6-14 times wider than those used in conventional systems. The algorithm has been installed in a commercial system that achieved the world's fastest scanning speed of 80 microm/s. The height resolution of the system is of the order of 10 nm for a measurement range of greater than 100 microm.     

Microscopic tomography with ultra-HVEM and applications

The ultra-HVEM with an accelerating voltage of 3 MV at Osaka University is capable of achieving excellent penetration and resolution for thick specimens. We obtained images of 5-microm-thick slices tilted at angles of up to 70 degrees for biological samples and observed stick-shaped samples of Si devices free from missing zone. These features make the ultra-HVEM an invaluable extension of 3D observation by electron tomography. In this paper, we introduce aspects of ultra-HVEM tomography; specifically, the magnification, the amount of image blurring for thick samples and the electron staining method. Finally, we give some typical applications in the fields of cell biology, pathology and electrical engineering.