Expression and characterization of disulfide bond use of oligomerized A2-Pancortins: Extracellular matrix constituents in the developing brain

The region-specific characteristics of the extracellular matrix are crucial for diverse functions in the brain. Pancortins/neuron-specific olfactomedin-related glycoproteins are components of the extracellular matrix. They comprise four alternatively spliced variants, Pancortin-1 to -4, which share a common portion, the B part, in the middle of their structure, have two pairs of alternatively spliced 5' regions, A1 and A2, and 3' regions, C1 and C2. Here we demonstrate that in mice, Pancortin-3 (A2-B-C1) and Pancortin-4 (A2-B-C2), which we have grouped together the A2-Pancortins, were transcribed early during the development of the brain in a region specific manner and were expressed very stably in vivo. They are N-glycosylated and secreted. Furthermore, we examined their ontogenetical expression profiles in the developing thalamus using antiserum against the common B region, since transient expressions of their mRNAs were notable there. In the developing thalami, they lasted long in oligomerized form even after the transcription of their mRNAs decreased to an undetectable level. Further analyses revealed that cysteine residues that are located in the common B part are important for homo- and hetero-oligomer formation of A2-Pancortins. When we substituted cysteine residues 45 and 47 with serine residues in that common B part, oligomerization of the A2-Pancortins was highly disturbed.

Passively Q-switched Yb:Y(2)O(3 )ceramic laser with a GaAs output coupler

We report on the experimental studies of a diode-end-pumped passively Q-switched Yb:Y(2)O(3) ceramic laser with a GaAs wafer simultaneously as saturable absorber and output coupler. The Q-switched operation of the laser has an average output power of 0.51 W with a 17.7-W incident pump power. The Q-switched pulses with pulse energy of 7.7 microJ have been achieved. The minimum pulse width is measured to be about 50 ns with a repetition rate of 52.6 KHz. To our knowledge, this is the first demonstration on a passively Q-switched Yb:Y(2)O(3) ceramic laser.

Diode-end-pumped 4.2-W continuous-wave Yb:Y2O3 ceramic laser

We report on an efficient diode-end-pumped polycrystalline Yb:Y2O3 ceramic laser. Continuous-wave output power of 4.2 W at 1078 nm was obtained under pump power of 19.5 W. The corresponding slope efficiency was 29%. The beam quality factor (M2) at full pump power was measured to be 1.63. The threshold wavelengths of the laser at various output couplings were also investigated. It was found that the threshold wavelengths shifted approximately 5 nm when the reflectivity of the output coupler changed from 90% to 99.9%, as caused by the strong reabsorption effect in the ceramic sample.

Electron microscopy study on a new phase in β-titanium alloys aged at a high temperature

In a Ti-20mass%Mo alloys aged by two steps aging at 623 and 823K, a new phase has been observed. In the first step aging, [Formula: see text] -phase crystals appear and at the second step aging, these crystals disappear and are replaced with the newly discovered phase crystals. Observations in the dark field image and analysis of composition of the new phase crystals have shown that the formation is closely related to the [Formula: see text] -phase structure. The new phase crystals have been also observed in four kinds of [Formula: see text] -type Ti alloys and a ( [Formula: see text] ) type Ti alloy aged at high elevated temperatures. Based on high-resolution electron microscope observations, the atomic structure of the new phase is assumed.

Diode-pumped mode-locked Yb3+:Y2O3 ceramic laser

A diode-pumped femtosecond ytterbium laser with a host material of Y2O3 ceramics is reported. Passive mode locking by a semiconductor saturable-absorber mirror generates 98-MHz, 615-fs pulses at a center wavelength of 1076.5 nm. The average power is 420 mW and the pulse energy is 4.3 nJ with a 2.6-W absorbed pump power. To our knowledge, this is the first continuous-wave mode-locked ceramic laser.

Dose-dependent differences in the profile of mutations induced by carcinogenic (R,S,S,R) bay- and fjord-region diol epoxides of polycyclic aromatic hydrocarbons

Chinese hamster V79 cells were exposed to a high or low concentration of the highly carcinogenic (R,S,S,R) or the less active (S,R,R,S) bay- or fjord-region diol epoxides of benzo[a]pyrene, benzo[c]phenanthrene or dibenz[c,h]acridine. Independent 8-azaguanine-resistant clones were isolated, and base substitutions at the hypoxanthine (guanine) phosphoribosyltransferase (hprt) locus were determined. For the three (R,S,S,R) diol epoxides studied, the proportion of mutations at AT base pairs increased as the concentration of diol epoxide decreased. Concentration-dependent differences in the mutational profile were not observed, however, for the three (S,R,R,S) diol epoxides. In studies, with V-H1 cells (a DNA repair deficient variant of V79 cells), a concentration-dependent difference in the profile of mutations for the (R,S,S,R) diol epoxide of benzo[a]pyrene was not observed. These results suggest that concentration-dependent differences in the mutational profile are dependent on an intact DNA repair system. In additional studies, we initiated mouse skin with a high or low dose of benzo[a]pyrene and promoted the mice for 26 weeks with 12-O-tetradecanoylphorbol-13-acetate. Papillomas were examined for mutations in the c-Ha-ras proto-oncogene. Dose-dependent differences in the profile of c-Ha-ras mutations in the tumors were observed. In summary, (i) dose-dependent differences in mutational profiles at the hprt locus were observed in Chinese hamster V79 cells treated with several highly mutagenic and carcinogenic (R,S,S,R) bay- or fjord-region diol epoxides but not with their less active (S,R,R,S) diol epoxide enantiomers, (ii) a dose-dependent difference in the mutational profile was not observed for the (R,S,S,R) diol epoxide of benzo[a]pyrene in a DNA-repair defective V79 cell line, and (iii) a dose-dependent difference in the mutational profile in the c-Ha-ras proto-oncogene was observed in tumors from mice treated with a high or low dose of benzo[a]pyrene.