Production of eicosapentaenoic acid by a recombinant marine cyanobacterium, Synechococcus sp.

The eicosapentaenoic acid (EPA) synthesis gene cluster from an EPA-producing bacterium, Shewanella sp. SCRC-2738, was cloned into a broad-host range vector, pJRD215, and then introduced into a marine cyanobacterium, Synechococcus sp. NKBG15041c, by conjugation. The transconjugant cyanobacteria produced 3.7±0.2% (2.24±0.13 mg/L) EPA (n-3) and 2.5 ±0.2% (1.49±0.06 mg/L) eicosatetraenoic acid (n-3) of the total fatty acids when the cells were cultured at 23°C at a light intensity of 1,000–1,500 Lux. The EPA and eico-satetraenoic acid contents of the cells were increased to 4.6±0.6% (3.86±1.11 mg/L) and 4.7±0.3% (3.86±0.82 mg/L), and 7.5±0.3% (1.76±0.10 mg/L) and 5.1±0.2% (1.19±0.06 mg/L) when they were cultured at low temperature (18°C) and at lower light intensity (40 Lux), respectively.     

Moisturizing effect of vesicles formed from monoglycerides on human skin

The moisturizing effect of vesicles formed from monoglycerides on human skin was studied by measurement of conductance on and transepidermal waterloss from the skin surface. Although sonication of the monoglycerides in water with Ca2+ gave multilamellar vesicles, the lamellar structure of the vesicles disappeared during their storage without any other additive. With the addition of poly(vinylpyrrolidone) after the sonication, the stability of the vesicles increased and their lamellar structure was maintained for 3 months at 40 degrees C. These vesicles led to a significantly higher water content of the stratum corneum of human skin compared with non-lamellar monoglyceride, and consequently they improved rough human skin.     

Endothelin A-receptor blockade worsens endotoxin-induced hepatic microcirculatory changes and necrosis

BACKGROUND & AIMS: Endothelin 1 is considered to be an important regulator of sinusoidal blood flow and increases during endotoxemia. The purpose of this study was to investigate the role of endothelin 1 in hepatic microcirculation, oxygen transport, and liver injury during endotoxemia. METHODS: Male Sprague-Dawley rats were continuously infused with 2.5 mL/h of saline, 0.8 mg . kg-1 . h-1 of lipopolysaccharide (LPS), 3 mg . kg-1 . h-1 of BQ-485, an endothelin A-receptor antagonist, or LPS plus BQ-485 for 7 hours. RESULTS: BQ-485 infusion had no significant effect on hepatic microcirculation and liver injury. LPS increased the plasma levels of aspartate aminotransferase (AST) and total bilirubin and decreased the hepatic adenosine triphosphate (ATP) level and bile flow rate. LPS + BQ-485 infusion further increased the plasma levels of AST and total bilirubin and decreased the bile flow rate and the hepatic ATP level. Dual-spot microspectroscopy revealed mild decreases in sinusoidal erythrocyte velocity and oxygen transport in the LPS group and profound decreases in these parameters in the LPS + BQ-485 group. Histological examinations revealed massive necrotic changes in the pericentral regions of the LPS + BQ-485 group. CONCLUSIONS: These results suggest that blockade of endothelin A receptors disturbs hepatic microcirculation and oxygen transport and aggravates the necrotic injury induced by endotoxin.     

Noncompetitive inhibition by L-cysteine and activation by L-glutamate of the iron-oxidizing activity of a mixotrophic iron-oxidizing bacterium strain OKM-9

A mesophilic, mixotrophic iron-oxidizing bacterium strain OKM-9 uses ferrous iron as a sole source of energy and L-glutamate as a sole source of cellular carbon. Uptake of L-glutamate into OKM-9 cells is absolutely dependent on ferrous iron oxidation. Thus, the Fe(2+)-dependent L-glutamate uptake system of strain OKM-9 is crucial for the bacterium to grow mixotrophically in iron medium with L-glutamate. The relationship between iron oxidation and L-glutamate transport activities was studied. Iron oxidase containing cytochrome a was purified 9-fold from the plasma membrane of OKM-9. A purified iron oxidase showed one rust-colored band following disc gel electrophoresis after incubation with Fe(2+). The Fe(2+)-dependent L-glutamate transport system was also purified 14.5-fold from the plasma membrane using the same purification steps as for iron oxidase. Fe(2+)-dependent L-glutamate and L-cysteine uptake activities of OKM-9 were 0.36 and 0.24 nmol/mg/min, respectively, when a concentration of 18 mM of these amino acids was used as a substrate. Both uptake activities were completely inhibited by potassium cyanide (KCN), suggesting that cytochrome a in the iron oxidase is involved in the transport process. The iron-oxidizing activity of strain OKM-9 was activated 1.7-fold by 80 mM L-glutamate. In contrast, the activity was noncompetitively inhibited by L-cysteine. The Michaelis constant of iron oxidase for Fe(2+) was 12.6 mM and the inhibition constant for L-cysteine was 41.6 mM. A marked inhibition of iron oxidase by 50 mM L-cysteine was completely reversed by the addition of 60 mM L-glutamate. The results suggest the possibility that iron oxidase has a binding site for L-cysteine and the cysteine first bound to the iron oxidase was replaced by the added L-glutamate.     

Simulation of confined and enhanced optical near fields for a long narrow aperture in a pyramidal structure on a thick metallic screen

A new type of long narrow aperture in a pyramidal structure on a thick metallic screen is proposed, and optical wave scattering by this structure is simulated. This aperture structure provides high emission intensity and small spot size simultaneously through excitation of the surface plasmon polaritons on the sidewalls of the pyramidal structure. Scattering of optical waves by this structure in the thick metallic screen is solved numerically with a volume integral equation by generalized conjugate residual iteration and fast Fourier transformation. The basic characteristics of the near-field intensities of the aperture are investigated in detail.     

Analysis and numerical computation of diffraction of an optical field by a subwavelength-size aperture in a thick metallic screen by use of a volume integral equation

Diffraction of an optical field by an aperture in a thick metallic screen is analyzed numerically by use of a three-dimensional volume integral equation together with a generalized conjugate residual method and fast Fourier transformation. Numerical results were validated by reciprocity and the independence of the results of the truncated discretized volume size used in numerical calculations. Near and far fields of square, circular, and triangular apertures in a thick screen are obtained numerically. Some of the numerical results obtained in the present study agree with previously reported experimental results. The surface plasmon polaritons excited on the sidewalls of the aperture can explain the basic characteristics of near-field distribution of apertures. The Bethe-Bouwkamp theory was found to be insufficient to explain the basic characteristics of the near field around the subwavelength aperture in a practical metallic screen.     

The kinetics of hydrolytic polymerization of ε-caprolactam. II. Determination of the kinetic and thermodynamic constants by least-squares curve fitting

The kinetic and thermodynamic constants of the hydrolytic polymerization of ?-caprolactam were determined by least-squares curve fitting. The calculations were carried out using observed kinetic data such as concentration of ?-caprolactam ([CL]), endgroup ([EG]), and ?-aminocaproic acid ([ACA]) and time derivatives of each concentration (rates) ?[CL]/?t, ?[EG]/?t, and ?[ACA]/?t. The sets of the converged constants are obtained for the initial water concentrations of 0.42, 0.82, and 1.18 mole/kg. An averaged set of the constants applicable for this range of the initial composition was also evaluated. The compatibility between observed and calculated concentration and rate curves was improved by the use of the newly developed sets of the constants. The mechanism of the polycondensation reaction is also discussed, based on the rate and kinetic constants obtained by this work.