Use of a YAP1 overexpression cassette conferring specific resistance to cerulenin and cycloheximide as an efficient selectable marker in the yeast Saccharomyces cerevisiae.

Drug-resistance markers for yeast transformation are useful because they can be applied to strains without auxotrophic mutations. However, they are susceptible to technical difficulties, namely lower transformation efficiency and the appearance of drug-resistant mutants without the marker. To avoid these problems, we have constructed a phosphoglycerate kinase (PGK) promoter-driven YAP1 expression cassette, called PGKp-YAP1. Yeast cells containing PGKp-YAP1 were resistant to cycloheximide, a protein synthesis inhibitor, and also to cerulenin, a fatty acid synthesis inhibitor, but not to other drugs tested. The transformation efficiency of PGKp-YAP1 using cerulenin selection was comparable to that using a URA3 auxotrophic marker when low concentrations of cerulenin were used. Non-transformed drug-resistant colonies did appear on the low-concentration cerulenin plates. However, these non-transformed colonies could easily be identified, based on their cycloheximide sensitivity and/or their resistance to aureobasidin A to which the transformants were sensitive. Therefore, the dual drug resistance of PGKp-YAP1 could be used as an effective selection for PGKp-YAP1 recipient cells. The PGKp-YAP1 marker was used to disrupt the LYS2 gene and to transform an industrial yeast strain, indicating that this marker can be used for efficient and reliable gene manipulations in any Saccharomyces cerevisiae strain.     

The structure and maximal gain of CW-pumped GaP-AlGaP semiconductor Raman amplifier with tapers on both sides

GaP-AlGaP waveguide semiconductor Raman amplifiers (SRAs) tapered on both sides were fabricated by high-quality GaP-AlGaP liquid phase epitaxial growth using the temperature difference method with controlled vapor pressure (TDM-CVP), photolithography patterning, and reactive ion etching with PCl/sub 3/ gas. Although the finesse of the both-sides-tapered waveguide SRA is lower than previous values for straight or one-side-tapered waveguides, the CW-pumped gain was maximized, and a maximal gain of 4.2 dB was obtained. This letter presents the effect of tapered structures in SRA with CW pumping amplification.     

Methanation of carbon deposited directly from CO2 on rhodium-bearing activated magnetite

Methanation reactivity was studied for the surface carbon deposited from CO₂ on the surface of Rh-bearing activated magnetite. The most active material (Rh=0.83 wt %) for methanation was prepared by the impregnation method at 60°C and showed 98% conversion at 300°C. The surface carbon was composed of elemental carbon (-carbon) and polymerized carbon (-carbon), the proportion being dependent on the density of carbon deposited. In temperature-programmed surface reaction, the extent of conversion of the - and -carbon to CH₄ was 0.34 (-carbon) and 0.53 (-carbon), respectively, and the total conversion was 0.87. This result indicates that not only elemental carbon but polymerized carbon (-carbon) could be converted to CH₄ on the Rh-bearing activated (-carbon) magnetite, whereas -carbon is not hydrogenated on activated magnetite.     

Fabrication of semi-transparent superoleophobic thin film by nanoparticle-based nano–microstructures on see-through fabrics

Superoleophobic thin films have many potential applications including fluid transfer, fluid power systems, stain-resistant and antifouling materials, and microfluidics. Transparency is also desired with superhydrophobicity for numerous applications; however, transparency and oleophobicity are almost incompatible with each other from the point of view of surface structure. Oleophobicity requires a rougher structure on the nano–microscale than hydrophobicity, and this rough structure brings light scattering. So far, there are few reports of compatible transparency and superoleophobicity. In this report, we propose see-through-type fabrics having nanoparticle-based hierarchical structure thin films to improve both oleophobicity and transparency. The vacant space between the fibers of the fabric has two important roles: to allow light to pass through and to induce an air layer to produce a Cassie state of a liquid droplet on the resulting thin film. To realize a low surface energy and nanoscale rough structured surface on fabric fibers, we used a spray method with perfluoroalkyl methacrylic copolymer, silica nanoparticles, and volatile solvent. Scanning electron microscopy images revealed that hierarchical nanoparticle structures were uniformly formed on the fabrics. The transparency of the obtained thin film was approximately 61 %, and the change of transparency between the non-coated and coated fabrics was 11 %. The contact angles of oil (rapeseed oil and hexadecane) and water droplets on the fabricated film were observed to be over 150° during investigation of its surface wettability.     

A positive selection for plasmid loss in Saccharomyces cerevisiae using galactose-inducible growth inhibitory sequences

Counter-selections for the loss of introduced plasmid sequences are useful for gene manipulations in yeast. We have used GAL10 promoter-mediated overexpression of GIN sequences, which inhibit the growth of cells, to develop a novel counter-selection system. Yeast cells carrying a GIN sequence grow normally on glucose medium but are unable to grow on galactose medium, whereas derivatives that have lost the GIN sequence are able to grow in the presence of galactose. We constructed autonomously replicating, integrating, and disruption plasmids carrying GIN sequences and tested their use to select for loss of the plasmid. The results showed that the GIN sequences provide a selection for efficient loss of plasmids or integrated constructs from yeast during growth on galactose medium, indicating that this system can be used for plasmid shuffling, gene replacements and marker gene recycling. This counter-selection system has wide application, because any Gal+ strain and a wide variety of marker genes can be used. In addition, counter-selection systems using growth-inhibitory sequences should be applicable to other yeasts and possibly to other organisms.     

Cross-correlation measurement without mechanical delay scanningusing electronically controlled wavelength-tunable femtosecond solitonpulse

A novel cross-correlation measurement system without mechanical action has been demonstrated in which the delay time between the reference and signal pulse can be electronically scanned by utilising the soliton self-frequency shift and the chromatic dispersion in the optical fibre. In this system, the reference pulse is the ideal femtosecond soliton pulse. The scanning range, the resolution and the scanning speed of the delay time can be arbitrarily changed only by the electronic control     

Miscibility gap due to ordering in the BCC Fe-Ge system

Phase equilibria in the bcc Fe-Ge system have been investigated by means of electron probe microanalysis and transmission electron microscopy. Two kinds of ordered phases, B2 and DO₃ types, have been detected, the B2 phase being formed from the disordered A2 phase by a 2nd order transition. The DO₃ phase is also formed from the B2 phase by a 2nd or higher order transition at higher temperatures. Below about 820 °C, however, the transition becomes a 1st order, and a miscibility gap between these ordered phases occurs in the composition range from 13 to 16 at. pct Ge. It has been also confirmed that the solubility of Ge in the bec phase shows a retrogression due to the formation of DO₃ phase. On the basis of these experimental results, the phase diagram for the Fe-Ge system has been partly revised.