Chung-Ang University

About: Chung-Ang University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Thin film. The organization has 13381 authors who have published 26978 publications receiving 416735 citations. The organization is also known as: CAU & Chung.

Recombinant Escherichia coli as a biofactory for various single- and multi-element nanomaterials.

Abstract: Nanomaterials (NMs) are mostly synthesized by chemical and physical methods, but biological synthesis is also receiving great attention. However, the mechanisms for biological producibility of NMs, crystalline versus amorphous, are not yet understood. Here we report biosynthesis of 60 different NMs by employing a recombinant Escherichia coli strain coexpressing metallothionein, a metal-binding protein, and phytochelatin synthase that synthesizes a metal-binding peptide phytochelatin. Both an in vivo method employing live cells and an in vitro method employing the cell extract are used to synthesize NMs. The periodic table is scanned to select 35 suitable elements, followed by biosynthesis of their NMs. Nine crystalline single-elements of Mn3O4, Fe3O4, Cu2O, Mo, Ag, In(OH)3, SnO2, Te, and Au are synthesized, while the other 16 elements result in biosynthesis of amorphous NMs or no NM synthesis. Producibility and crystallinity of the NMs are analyzed using a Pourbaix diagram that predicts the stable chemical species of each element for NM biosynthesis by varying reduction potential and pH. Based on the analyses, the initial pH of reactions is changed from 6.5 to 7.5, resulting in biosynthesis of various crystalline NMs of those previously amorphous or not-synthesized ones. This strategy is extended to biosynthesize multi-element NMs including CoFe2O4, NiFe2O4, ZnMn2O4, ZnFe2O4, Ag2S, Ag2TeO3, Ag2WO4, Hg3TeO6, PbMoO4, PbWO4, and Pb5(VO4)3OH NMs. The strategy described here allows biosynthesis of NMs with various properties, providing a platform for manufacturing various NMs in an environmentally friendly manner.

Elongation and gravitropic responses of Arabidopsis roots are regulated by brassinolide and IAA

Abstract: Exogenously applied brassinolide (BL) increased both gravitropic curvature and length of primary roots of Arabidopsis at low concentration (10−10 M), whereas at higher concentration, BL further increased gravitropic curvature while it inhibited primary root growth. BRI1-GFP plants possessing a high steady-state expression level of a brassinosteroid (BR) receptor kinase rendered the plant's responses to gravity and root growth more sensitive, while BR-insensitive mutants, bri1-301 and bak1, delayed root growth and reduced their response to the gravitropic stimulus. The stimulatory effect of BL on the root gravitropic curvature was also enhanced in auxin transport mutants, aux1-7 and pin2, relative to wild-type plants, and increasing concentration of auxin attenuated BL-induced root sensitivity to gravity. Interestingly, IAA treatment to the roots of bri1-301 and bak1 plants or of plants pretreated with a BL biosynthetic inhibitor, brassinazole, increased their sensitivity to gravity, while these treatments for the BL-hypersensitive transgenic plants, BRI1-GFP and 35S-BAK1, were less effective. Expression of a CYP79B2 gene, encoding an IAA biosynthetic enzyme, was suppressed in BL-hypersensitive plant types and enhanced in BL-insensitive or -deficient plants. In conclusion, our results indicate that BL interacts negatively with IAA in the regulation of plant gravitropic response and root growth, and its regulation is achieved partly by modulating biosynthetic pathways of the counterpart hormone.

Global well-posedness and stability of constant equilibria in parabolic-elliptic chemotaxis systems without gradient sensing

Abstract: This paper deals with a Keller–Segel type parabolic–elliptic system involving nonlinear diffusion and chemotaxis in a smoothly bounded domain , , under no-flux boundary conditions. The system contains a Fokker–Planck type diffusion with a motility function , . The global existence of the unique bounded classical solutions is established without smallness of the initial data neither the convexity of the domain when , or , . In addition, we find the conditions on parameters, and , that make the spatially homogeneous equilibrium solution globally stable or linearly unstable.

Inhibitory effect of rapamycin on corneal neovascularization in vitro and in vivo.

Abstract: PURPOSE. To examine the effect of rapamycin on the proliferation and the migration of human umbilical vein endothelial cells (HUVECs) and on the corneal neovascularization in the corneal alkaline burn murine model. METHODS. HUVEC proliferation, migration, and apoptosis were examined after treatment with rapamycin. The effect of rapamycin on the mRNA expression of FK506 binding protein (FKBP)-12 and mammalian target of rapamycin (mTOR) was also evaluated in vitro. Corneal neovascularization was induced in vivo by an alkaline burn of the cornea with 1 N NaOH on BALB/c mice. Rapamycin was given intraperitoneally at 2 mg/kg body weight once a day for 12 days after the corneal alkaline burn. Growth factors and cytokines related with neovascularization and inflammation were evaluated in the corneal tissue and the peripheral blood by reverse transcription‐polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The corneal neovascularization was evaluated by a slit lamp biomicroscopy. RESULTS. Rapamycin at the concentration of 1000 ng/mL for 48 hours’ exposure significantly inhibited the growth of HUVECs. The double chamber assay showed that rapamycin dramatically inhibited the migration of HUVECs at concentrations of 10 and 100 ng/mL and that these concentrations did not affect endothelial cell growth. When TUNEL assays were performed, the number of apoptotic cells increased 1.9-, 2.1-, and 2.6-fold compared with the control at 10, 100, and 1000 ng/mL, respectively, of rapamycin at 48 hours of exposure. RT-PCR showed that the expression of mTOR was suppressed in the HUVECs after rapamycin treatment; however, FKBP-12 expression was not affected. Among the angiogenic factors, gene expression of substance P and hypoxia inducible factor (HIF)-1 was inhibited by rapamycin earlier (1‐3 days), with vascular endothelial growth factor (VEGFR)-1 gene expression being suppressed for the first 7 days in the corneal tissue. The protein level of substance P and vascular endothelial growth factor (VEGF) was significantly decreased—more in mice treated with rapamycin than the control mice—as shown by ELISA assay of peripheral blood. Furthermore, rapamycin significantly inhibited corneal neovascularization in the alkalineburned cornea. CONCLUSIONS. Rapamycin strongly inhibited HUVEC migration at doses that did not cause cytotoxicity and apoptosis in this in vitro model. Rapamycin also suppressed corneal neovascularization, possibly by inhibiting proinflammatory cytokines, as shown by the in vivo study. Therefore, rapamycin may be useful as an angiogenic regulator in the treatment of corneal diseases that manifest with neovascularization. (Invest Ophthalmol Vis Sci. 2005;46:454‐460) DOI:10.1167/iovs.04-0753

Survey of Clinical Laboratory Practices for 2015 Middle East Respiratory Syndrome Coronavirus Outbreak in the Republic of Korea.

Abstract: Background It is crucial to understand the current status of clinical laboratory practices for the largest outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) infections in the Republic of Korea to be well prepared for future emerging infectious diseases.