Chemodynamics of Lyman alpha emitters, Lyman break galaxies and elliptical galaxies

We report an ultra-high-resolution simulation that follows evolution from the earliest stages of galaxy formation through the period of dynamical relaxation. The bubble structures of gas revealed in our simulation ($< 3\times 10^8$ years) resemble closely the high-redshift Lyman $\alpha$ emitters (LAEs). After $10^9$ years these bodies are dominated by stellar continuum radiation and look like the Lyman break galaxies (LBGs) known as the high-redshift star-forming galaxies at which point the abundance of elements appears to be solar. After $1.3\times10^{10}$ years, these galaxies resemble present-day ellipticals. The comparisons of simulation results with the observations of elliptical galaxies allow us to conclude that LAEs and LBGs are infants of elliptical galaxies or bulge systems in the nearby universe.Comment: To appear in the proceedings of the CRAL-Conference Series I "Chemodynamics: from first stars to local galaxies", Lyon 10-14 July 2006, France, Eds. Emsellem, Wozniak, Massacrier, Gonzalez, Devriendt, Champavert, EAS Publications Serie

Replacement of the Catalytic Nucleophile Aspartyl Residue of Dextran Glucosidase by Cysteine Sulfinate Enhances Transglycosylation Activity

Dextran glucosidase from Streptococcus mutans (SmDG) catalyzes the hydrolysis of an α-1,6-glucosidic linkage at the nonreducing end of isomaltooligosaccharides and dextran. This enzyme has an Asp-194 catalytic nucleophile and two catalytically unrelated Cys residues, Cys-129 and Cys-532. Cys-free SmDG was constructed by replacement with Ser (C129S/C532S (2CS), the activity of which was the same as that of the wild type, SmDG). The nucleophile mutant of 2CS was generated by substitution of Asp-194 with Cys (D194C-2CS). The hydrolytic activity of D194C-2CS was 8.1 × 10⁻⁴ % of 2CS. KI-associated oxidation of D194C-2CS increased the activity up to 0.27% of 2CS, which was 330 times higher than D194C-2CS. Peptide-mapping mass analysis of the oxidized D194C-2CS (Ox-D194C-2CS) revealed that Cys-194 was converted into cysteine sulfinate. Ox-D194C-2CS and 2CS shared the same properties (optimum pH, pI, and substrate specificity), whereas Ox-D194C-2CS had much higher transglucosylation activity than 2CS. This is the first study indicating that a more acidic nucleophile (-SOO−) enhances transglycosylation. The introduction of cysteine sulfinate as a catalytic nucleophile could be a novel approach to enhance transglycosylation

The Nature of Lya Blobs: Supernova-Dominated Primordial Galaxies

We consider a forming galaxy undergoing multitudinous supernova (SN) explosions, as a possible model of \lya blobs (LABs). For this purpose, an ultra--high resolution hydrodynamic simulation is performed using $1024^3$ grid points, where SN remnants are resolved with sufficient accuracy. It is found that multiple SN explosions produce kpc--size expanding hot bubbles, which drive cool, dense shells by strong shock. The colliding high--density cooling shells radiate intensive \lya emission, resulting in a high \lya luminosity of $\sim10^{43}$ erg s$^{-1}$, comparable to the observed level in LABs. Also, recently discovered bubbly features in some LABs are quite similar to the structure predicted in the present simulation. Furthermore, the result demonstrates that LABs are representative of evolving primordial galaxies; they could hold direct information on the early chemical enrichment of galaxies, contrary to present--day galaxies which have undergone intense recycling of interstellar matter, thus erasing most of the early chemical history. It turns out that the metal mixing proceeds in a very inhomogeneous fashion, so that there appears a large spread of metallicity, that is,$[{\rm Fe/H}] \approx 0 {\rm ~to} -5$ or $[{\rm O/H}] \approx 1 {\rm ~to} -4$. Hence, the early galactic chemical evolution may have proceeded in a different manner from that hitherto considered in one--zone models.Comment: 4 pages, 2 figures, accepted fot publicatin in ApJ

AA amyloidosis-resistant CE/J mice have Saa1 and Saa2 genes that encode an identical SAA isoform

The CE/J mouse strain is resistant to amyloid A protein (AA) amyloidosis. In contrast to AA amyloidosis-susceptible mouse strains that concomitantly express serum amyloid A precursor protein (SAA) types 1 and 2 isoforms encoded by the Saa1 and Saa2 genes, respectively, in response to inflammatory stimulation from the liver, CE/J mice express only a single SAA isoform named SAA2.2. In addition, CE/J mice uniquely possess a Q30L amino acid substitution in SAA2.2 that inhibits amyloidogenesis. To elucidate the genetic basis underlying the expression of only a single SAA isoform in this strain, we conducted PCR cloning and nucleotide sequencing of the Saa1 and Saa2 genes from the CE/J genome. We revealed that CE/J mice possess functional Saa1 and Saa2 genes. Intriguingly, the two genes were identical with respect to amino acid sequence, each encoding the SAA2.2 isoform. RT-PCR analysis of inflamed liver tissue from CE/J mice demonstrated that both genes are expressed at equivalent levels. Reporter assays revealed that promoter/enhancer sequences of Saa1 and Saa2 genes in CE/J are also functional. These results indicate that the SAA2.2 isoform in CE/J is a mixture of Saa1 and Saa2 gene products.ArticleAMYLOID-JOURNAL OF PROTEIN FOLDING DISORDERS. 21(1):1-8 (2014)journal articl

Development of Track Condition Monitoring System Using Onboard Sensing Device

Monitoring the conditions of railway tracks is essential for ensuring the railway safety. In-service vehicles equipped with sensors and GPS systems can act as probes to detect and analyse real-time vehicle vibration. Recently, a compact on-board sensing device has been developed. This chapter describes the track condition monitoring system that uses a compact on-board sensing device and diagnosis software. The diagnosis software provides the function of detecting track faults using the root mean square (RMS) of the car-body acceleration. It also allows analysis in the time-frequency domain using wavelet transform. A monitoring experiment in a local railway line showed that the system is effective for practical application