One-pot synthesis and structural characterization of poly(alkoxysilane)s catalyzed by silver-gold complexes.

Cheong, Hyeonsook,Roh, Sung-Hee,Cho, Myong-Shik,Kim, Myoung-Hee,Woo, Hee-Gweon,Yang, Kap-Seung,Kim, Bo-Hye,Jun, Jin,Sohn, Honglae American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.1

<P>Combinative one-pot Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), mediated by a mixture of AgNO3-AuCl3 (100/1 mole ratio) rapidly produced poly(alkoxysilane)s in reasonably high yield. The addition of small amount of gold complex to the reaction mixture effectively accelerated the coupling reaction compared to the reaction rate with AgNO3 alone. The hydrosilanes include p-X-C6H4SiH3 (X = H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2. The alcohols include MeOH, EtOH, iPrOH, PhOH, and CF3(CF2)2CH2OH. The weight average molecular weight and polydispersity of the poly(alkoxysilane)s were in the range of 1,600-8,000 Dalton and 1.4-3.5, respectively. The dehydrocoupling reactions of phenylsilane with ethanol (1:3 mole ratio) in the presence of the Ag-Au complexes gave only triethoxyphenylsilane.</P>

Plasmid Rescue of Flavonoid-3'-Hydroxylase Gene in A. thaliana

Cheong, Hyeonsook CHOSUN UNIVERSITY 1997 Basic Science and Engineering Vol.1 No.1

Flavonoids are secondary metabolites that serve as a marker in a flower and anther development. We have investigated the developmental changes in the accumulation of flavonoids in flower organs and pollen tube growth in the pistils of a flavonoid deficient chalcone synthase mutant (tt4) and a sinapate ester deficient mutant (fahl-7) of Arabidopsis thaliana. Pollen tube growth was depended on the genotype and flower maturity. On the other hand, the tt7 mutant of Arabidopsis is defective in the accumulation of a flavnol. Earlier results indicated the tt7 locus encodes flavonoid-3'-hydroxylase (F-3'-OH) in the general phenylpropanoid pathway. Based upon the green fluorescence of tt7 mutants under UV light, mutant lines were identified from Agrobacterium mediated transformants carrying disrupted gene with the T-DNA. This was based upon the visual screening. The T-DNA tagged line 7190 was certified by Southern hybridization using petunia F-3'-OH gene as a probe. Plasmid rescue was conducted using the genomic DNA isolated from the 7190 mutant. The DNA was digested with EcoRI and self-ligated. Several DNA clones containing the sequence of F-3'-OH gene of A. thaliana were identified using petunia F-3'-OH gene as a probe. One positive clone (pA11) was characterized by restriction digestions and nucleotide sequencing.

Effects of pine needle extract on pacemaker currents in interstitial cells of Cajal from the murine small intestine.

Cheong, Hyeonsook,Paudyal, Dilli Parasad,Jun, Jae Yeoul,Yeum, Cheol Ho,Yoon, Pyung Jin,Park, Chan Guk,Kim, Man Yoo,So, Insuk,Kim, Ki Whan,Choi, Seok Korean Society for Molecular Biology 2005 Molecules and cells Vol.20 No.2

<P>Extracts of pine needles (Pinus densiflora Sieb. et Zucc.) have diverse physiological and pharmacological actions. In this study we show that pine needle extract alters pacemaker currents in interstitial cells of Cajal (ICC) by modulating ATP-sensitive K+ channels and that this effect is mediated by prostaglandins. In whole cell patches at 30 degrees , ICC generated spontaneous pacemaker potentials in the current clamp mode (I = 0), and inward currents (pacemaker currents) in the voltage clamp mode at a holding potential of -70 mV. Pine needle extract hyperpolarized the membrane potential, and in voltage clamp mode decreased both the frequency and amplitude of the pacemaker currents, and increased the resting currents in the outward direction. It also inhibited the pacemaker currents in a dose-dependent manner. Because the effects of pine needle extract on pacemaker currents were the same as those of pinacidil (an ATP-sensitive K+ channel opener) we tested the effect of glibenclamide (an ATP-sensitive K+ channels blocker) on ICC exposed to pine needle extract. The effects of pine needle extract on pacemaker currents were blocked by glibenclamide. To see whether production of prostaglandins (PGs) is involved in the inhibitory effect of pine needle extract on pacemaker currents, we tested the effects of naproxen, a non-selective cyclooxygenase (COX-1 and COX-2) inhibitor, and AH6809, a prostaglandin EP1 and EP2 receptor antagonist. Naproxen and AH6809 blocked the inhibitory effects of pine needle extract on ICC. These results indicate that pine needle extract inhibits the pacemaker currents of ICC by activating ATP-sensitive K+ channels via the production of PGs.</P>

Interaction of brassinosteroids and cytokinin in modulating light mediated signaling in Arabidopsis

Indeok Hwang, Dilli P. Paudyal, Hyeonsook Cheong 조선대학교 기초과학연구원 2008 조선자연과학논문집 Vol.1 No.1

Brassinosteroids (BRs) are a special class of plant steroid hormones that are essential for normal growth and development. Part of confusion is whether BRs are unique to plants, because they have overlapping physiological roles with other better-studied hormones and with physiological responses caused by light. In systems designed to assay for cytokinins, the effects of BRs vary. We measured hypocotyl length for testing the ability of brassinolide (BL) to rescue double mutant between det2 and the photoreceptor null mutant phytochrome B (phyB). PHYB involved in controlling hypocotyl elongation in increased concentration of BL whereas phyBdet2 double mutant just partially rescue to phyB in white and red light indicated the involvement of BRs in PHYB regulated cell elongation. BRs regulated hypocotyl growth was delayed by BAP, a cytokinin treatment but inhibitory effects of BAPs on hypocotyl growth was slightly recovered by BL. The result indicated that the mode of action of BR and cytokinin is independent or sequential in the downstream light-regulated response control on hypocotyl elongation and also light modulated the action of BR and cytokinin in some extent.

Vector Construction for the Tissue Specific Expression and Production of IL-2 Gene in Potato : Solanum tuberosum cv. Superior

Park, Yoonkyung,Cheong, Hyeonsook 조선대학교 기초과학연구소 1997 自然科學硏究 Vol.20 No.1

We constucted two expression vetors, pSSK-1 and pSSK-6, carrying IL-2 gene for the purpose of estimating the amount of its products and the effects in the potato. The pSSK-6 is under the control of 35S CaMV promoter(pSSK-1) specifically expressed in potato tuber. Also, pSSK-1, a binary vector carrying interleukin-2 (IL-2) gene, was constructed to be examine the possibility of the production of IL-2 and its effects in potato, and transferred into A. tumefaciens for the sake of the transformation of potato (solanum tuberosum cv. Superior). In our recent work, we verified that IL-2 gene from pSSK-1 vector was expressed in all parts of the transformed potato plant. However the amount of IL-2 protein was estimated very little.

The Effect of the Recombinant Human Interleukin-2 Gene in Potato : Solanum tuberosum cv. Superior

Park, Yoonkyung,Cheong, Hyeonsook 한국식물학회 2001 Journal of Plant Biology Vol.44 No.4

To examine the effect of the T-cell growth factor (human interleukin-2), we constructed a binary vector, pSSK-1, carrying the recombinant human interleukin-2 (rhlL-2) gene, and transferred it into Agrobacterium tumefaciens. Using this construct, we then transformed potato explants (Solanum tuberosum cv. Superior), achieving 100% regeneration of shoots on a modified MS medium. Of the putative transformed shoots, 81% rooted and were selected on 200㎎/L kanamycin. Both Southern and northern analyses verified the transformation events. An ELISA test also indicated that the rhIL-2 protein was produced from rhIL-2-transformed potatoes. To determine whether this protein was biologically active in the potato cells, we performed a biological assay using the IL-2 dependent cell line, CTLL-2. The suspension containing extract from the transformants showed significant proliferation of the IL-2 dependent CTLL-2 cells, whereas cells did not proliferate in the nontransformed potato. We then grew the verified rhlL-2 transgenic potatoes in soil, and compared their performance with that of nontransgenic potatoes as well as those that had been transformed with GUS. Growth rates, as calculated from plant heights, were up to 50% higher than for either the nontransgenic or the GUS-transformed potatoes. Similar patterns were found with Arabidopsis thaliana plants treated in the same manner. All of these results suggest that rhIL-2 may function as a growth factor in potato.

Transformation of Arabidipsis thaliana using root explants

Park, Yoonkyung,Cheong, Hyeonsook 조선대학교 부설생명과학 연구소 1998 생명과학 연구 Vol.6 No.-

The IL-2 gene is under the control of 35S CaMV promoter which makes its following gene to be expressed in whole plant. We constructed pSSK-1 carrying interleukin-2 gene to examine the IL-2 productivity and effects in Arabidopsis thaliana, and transferred into A. tumefaciens for the sake of the transformation of Arabidopsis ecotype C_(24). We used a simple and highly reproducible tissue-culture procedure to transform Arabidopsis with Agrobacterium tumefaciens as the gene delivery system and the roots of axenically grown plants as the explant source. Root segments were placed onto solidfied CIM (0.5 mg/L 2,4-D, 0.05 mg/L kinetin) medium in a petridish for 2 days, and transferred to solidfied SIM (5 mg/L 2IP, 0.15 mg/L IAA, 50mg/L kanamycin, 750 mg/L vancomycin) medium. Shoots were intermittently appeared from the green calli over the next several weeks.

Transformation of Arabidopsis thaliana using root explants

Park, Yoonkyung,Cheong, Hyeonsook 조선대학교 생명과학연구소 1998 생명과학 연구 Vol.6 No.-

The IL-2 gene is under the control of 35S CaMV promoter which makes its following gene to be expressed in whole plant. We constructed pSSK-1 carrying interleukin-2 gene to examine the IL-2 productivity and effects in Arabidopsis thaliana, and transferred into A. tumefaciens for the sake of the transformation of Arabidopsis ecotype C_(24). We used a simple and highly reproducible tissue-culture procedure to transform Arabidopsis with Agrobacterium tumefaciens as the gene delivery system and the roots of axenically grown plants as the explant source. Root segments were placed onto solidfied CIM (0.5 ㎎/L 2,4-D, 0.05 ㎎/L kinetin) medium in a petridish for 2 days, and transferred to solidfied SIM (5 ㎎/L 2IP, 0.15 ㎎/L IAA, 50 ㎎/L kanamycin, 750 ㎎./L vancomycin) medium. Shoots were intermittently appeared from the green calli over the next several weeks.

Regulation of the Renin-angiotensin system by Antihypertensive compounds isolated from Pinus densiflora sieb. et zucc.

Woong KIM,Hyeonsook CHEONG,Jaeyoung PARK,Hakjoon CHOI 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10

In vitro Regeneration of potato (Solanum tuberosum cv. Jopung) transformants

Park, Yoonkyung,Cheong, Hyeonsook 조선대학교 생명과학연구소 1997 생명과학 연구 Vol.5 No.-

Efficient plant regeneration has been achieved in the potato plant (Solanum tuberosum cv. Jopung). We found that a modified medium was given shoot regeneration within 10 weeks after explants infected with A. tumefaciens were cultured. Callus appeared at the cut edges of tuber discs and of stem segments, mainly at the basal parts calli were observed. Some explants started to form shoots and roots after two to three weeks in stage Ⅲ medium. They were then transferred to MS medium containing 200 ㎎/L kanamycin. The transformed shoots formed roots at the cut edge of the plantlets. In contrast. untransformed shoots did not form roots and became yellowish after a month in the same medium. In conclusion, we improved in vitro regeneration and transformation of potato using agrobacteria harboring β-glucuronidase (GUS) and modified media.