• Journal of Microbiology and Biotechnology
• /
• v.16 no.3
• /
• pp.381-385
• /
• 2006

The production of astaxanthin by Xanthophyllomyces dendrorhous mutant depended on the culture conditions. Therefore, a cultivation strategy, including effective chemical and light induction, for the high-level production of astaxanthin by X. dendrorhous mutant JH1 was explored. Effective chemicals such as ethanol, acetic acid, and hydrogen peroxide, which are known inducers or precursors of astaxanthin synthesis, were investigated for their increase of astaxanthin production. Each of 1.0% ethanol, 1.0% acetic acid, and 1.0% hydrogen peroxide increased the astaxanthin concentration to 49.77 mg/l, 46.33 mg/l, and 45.61 mg/l, respectively. Among these chemicals, 1.0% ethanol showed the best effect on increasing astaxanthin concentration after 48 h of cultivation. Under 1.0% ethanol feeding condition, high light intensity (2,400 lux) stimulated astaxanthin production to 59.67 mg/l, compared with that in the dark-grown cultivation.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.6
• /
• pp.969-973
• /
• 2006

Stimulatory effects of three different intermediate metabolites (1-hydroxy-2-naphthoate, salicylate, and catechol) as potential inducers on phenanthrene degradation were investigated using two different bacteria (Pseudomonas putida ATCC 17484 and Burkholderia cepacia PB12). The relative induction capacity was high in the sequence of 1-hydroxy-2-naphthoate, salicylate, and catechol in both strains. The highest of up to 12 times increase of the induction was obtained by the addition of 1-hydroxy-2-naphthoate in the strain PB12, compared with the control where no exogenous inducer was added. The induction capacity of the potential inducers was closely related with the number of oxygenations required per electron equivalents in one mole of the inducer.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.130-136
• /
• 2005

Induction hardening increases hardness near the surface where it's most needed, and leaves the surface in compression which improves fatigue life. Although case depth and chemical composition are same, the structure of induction hardened shaft affects the fatigue strength and life because of austenization during hardening. Therefore torsional fatigue tests of specimens from various structures, which are obtained by nomalizing, spheriodized annealing and tempering after quenching, were conducted on induction hardened automotive drive shafts with various case depths and loads applied in order to evalute the relation between structure and fatigue strength.

• Journal of Microbiology and Biotechnology
• /
• v.6 no.6
• /
• pp.451-455
• /
• 1996

Physiological studies on the expression of Bacillus thuringiensis subsp. tenebrionis (Btt) gene coding for insecticidal protein in recombinant Escherichia coli 537 were carried out to identify optimal culture condition. It was necessary to shift culture temperature from 30 to $42^{\circ}C$ to express the gene. Expression of the Btt toxin gene by recombinant E. coli 537 began within one hour after induction. Complex nitrogen sources increased production of the insecticidal protein. The total insecticidal protein was 0.5 g/I when using yeast extract as a complex nitrogen source. Soybean hydrolysate showed apparently the highest induction efficiency. After induction, the cellular content of the insecticidal protein was 5.4 times higher than it had been before induction. The optimal cultivation strategy was found to grow cells for 7hours at $30^{\circ}C$ and then 5-8 hours at $42^{\circ}C$. The optimal cultivation pH for the production of insecticidal protein was 6.5. The Btt toxin produced by the recombinant E. coli 537 was found to have the same level of potency against Colorado potato beetle as the original toxin.

• Bulletin of the Korean Chemical Society
• /
• v.10 no.3
• /
• pp.323-324
• /
• 1989

• Journal of the Korean Society of Industry Convergence
• /
• v.26 no.5
• /
• pp.813-823
• /
• 2023

In this study, microstructure, hardening layer hardness, and case depth were evaluated after induction hardening(IH) of base metal specimen(BM) treated with annealing and quenching-tempering specimen(QT) treated with quenching and tempering. The microstructure after IH was significantly influenced by the microstructure before IH and the induction coil heating movement speed, but the effect of the induction frequency was very small. The hardness of the hardened layer at an induction coil heating movement speed of 15 mm/s or less was more influenced by the microstructure before IH than the induction coil travel speed and induction frequency. The induction coil travel speed has the significantly effect on the case depth, the induction frequency has effect and the microstructure before IH has a small effect.

• Molecules and Cells
• /
• v.27 no.2
• /
• pp.243-250
• /
• 2009

Recent studies suggest a novel role of $HIF-1{\alpha}$ under nonhypoxic conditions, including antibacterial and antiviral innate immune responses. However, the identity of the pathogen-associated molecular pattern which triggers $HIF-1{\alpha}$ activation during the antiviral response remains to be identified. Here, we demonstrate that cellular administration of double-stranded nucleic acids, the molecular mimics of viral genomes, results in the induction of $HIF-1{\alpha}$ protein level as well as the increase in $HIF-1{\alpha}$ target gene expression. Whole-genome DNA microarray analysis revealed that double-stranded nucleic acid treatment triggers induction of a number of hypoxia-inducible genes, and induction of these genes are compromised upon siRNA-mediated $HIF-1{\alpha}$ knock-down. Interestingly, $HIF-1{\alpha}$ knock-down also resulted in down-regulation of a number of genes involved in antiviral innate immune responses. Our study demonstrates that $HIF-1{\alpha}$ activation upon nucleic acid-triggered antiviral innate immune responses plays an important role in regulation of genes involved in not only hypoxic response, but also immune response.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.11
• /
• pp.1641-1648
• /
• 2003

New and facile synthetic routes for preparation of optically active norephedrine, norpseudoephedrine and cathinone with high optical purities via double asymmetric induction by employing asymmetric reduction of 2-N-protected amino (or azido)-1-phenylpropanone and 2-methanesulfonyloxy-1-phenylpropanone with CBS-catalyzed-borane and $^dIpc_2BCl$ as chiral reducing agents are described.

• Bulletin of the Korean Chemical Society
• /
• v.12 no.5
• /
• pp.517-520
• /
• 1991

The reaction of dichlorophenylvinylsilane with tert-butyllithium in hydrocarbon solvents at room temperature or below generated the Z and E-isomers of 1-chloro-1-phenyl-2-neopentylsilene. The intermediates were trapped by cyclopentadiene, anthracene and methoxytrimethylsilane to give a consistent 90/10 ratio for the Z-silene to E-silene adduct. This result was interpreted as an evidence for stereochemical induction in the silene generation reaction.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1996.12a
• /
• pp.67-78
• /
• 1996