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Factors Affecting Agrobacterium tumefaciens-mediated Transformation of Panax ginseng C.A. Meyer
Ok-Tae Kim,Su-Jin Jung,Kyong-Hwan Bang,Young-Chang Kim,Yu-Su Shin,Jung-Sook Sung,Chun-Geon Park,Nak-Sul Seong,Seon-Woo Cha,Hee-Woon Park 한국약용작물학회 2007 한국약용작물학회지 Vol.15 No.2
A protocol for the production of transgenic Panax ginseng C.A. Meyer was established via Agrobacterium tumefaciens-mediated genetic transformation of direct somatic embryos. A number of conditions related to the co-cultivation were tested with respect to maximizing transformation efficiency. The results showed that pH of the co-cultivation medium (5.7), the bacterial growth phase (optical density; OD600 = 0.8), co-cultivation period (3 days), and acetosyringone concentration (100 μM) had positive effects on transformation. Selected plantlets were cultured on the medium at an elevated hygromycin level(30 mg/l). Integration of the transgenes into the P. ginseng nuclear genome was confirmed by PCR analysis using hpt primers and by Southern hybridization using hpt-specific probe. The transgenic plantlets were obtained after 3-month cultivation and did not show any detectable variation in morphology or growth characteristics compared to wild-type plants.
Ok-Tae Kim,Dong-Yun Hyun,Kyong-Hwan Bang,Su-Jin Jung,Young-Chang Kim,Yu-Su Shin,Dong-Hwi Kim,Swon-Won Kim,Nak-Sul Seong,Seon-Woo Cha,Hee-Woon Park 한국약용작물학회 2007 한국약용작물학회지 Vol.15 No.2
The cost of conventional cultivation of ginseng (Panax ginseng C.A. Meyer) is very expensive, because shadow condition should be maintained during cultivation periods owing to inherently weak plant for high-temperature. Therefore, application of plant biotechnology may be possible to overcome these difficulties caused by conventional breeding of ginseng. Transgenic plants were produced via Agrobacterium tumefaciens Gv3101, both carrying the binary plasmid pBI121 mLPISO with nptII and Iso (isoprene synthase) gene. Integration of the transgenes into the P. ginseng nuclear genome was confirmed by PCR analysis using nptII primers and Iso primers. RT-PCR result also demonstrated the foreign isoprene synthase gene in three transgenic plant lines (T1, T3, and T5) which was expressed at the transcriptional level. When whole plants of transgenic ginseng were exposed to high temperature at 46℃ for 1 h, a non-transformed plant was wilted from heat shock, whereas a transgenic plant appeared to remain healthy. We suggest that the introduction of exogenous isoprene synthase is considered as alternative methods far generating thermotolerance ginseng.
Ok Hwan Cha,Cheol-Hoi Kim,Jun Seok Lee,Jong Pil Jeong,Joong Seo Park,Jandi Kim,정현,Eun-Kyung Suh 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.1
The temperature dependence of the electroluminescence spectra of InGaN/GaN multi-quantumwell light-emitting diodes (LEDs) has been investigated over a range of temperatures and currents. The presence of localization effects in the active InGaN layers can be deduced from the observed considerable blue shifts of the electroluminescence emission peak with increasing temperature in the low-temperature region. Exciton-phonon couplings in the active layer are also observed at low temperatures. The electroluminescence intensity was measured to determine the internal quantum efficiency of the LEDs as a function of temperature. When the temperature decreases from room temperature to 170~200 K, the electroluminescence intensity increases due to a reduction in the nonradiative recombination, and the internal quantum efficiency is improved. At T < 170 K, the electroluminescence intensity is reduced significantly. This reduction of the electroluminescence intensity mainly results from the low carrier capture efficiency in the active layer due to the high Mg activation energy, the electron-hole separation in multi quantum wells, and the high internal piezoelectric field. However, in the case of LEDs using a narrow barrier, the electroluminescence intensity is reduced slightly at low temperatures. Therefore, in order to measure the internal quantum efficiency by using the temperature dependence of the electroluminescence spectra in LEDs, one must carefully consider the effects of carrier injection at low temperature.
Ok-Hwan Cha,Mun-Seok Jeong,Clare C. Byeon,Hyun Jeong,Jong-Hun Han,Young-Chul Choi,Kay-Hyeok An,Kyung-Hui Oh,Ki-Kang Kim,Young-Hee Lee 한국탄소학회 2009 Carbon Letters Vol.10 No.1
We propose an evaluation method of the relative content of single-walled carbon nanotubes (SWCNT) in SWCNT soot synthesized by arc discharge using UV-VIS-NIR absorption spectroscopy. In this method, we consider the absorbance of semiconducting and metallic SWCNTs together to calculate the relative content of SWCNTs with respect to a highly purified reference. Our method provides the more reliable and realistic evaluation of SWCNT content with respect to the whole carbonaceous content than the previously reported method.
Ok-Tae Kim,Kyong-Hwan Bang,Young-Chang Kim,Yu-Su Shin,Dong-Yun Hyun,Byong-Yel Yeon,Yeoung-Seuk Bae,Nak-Sul Seong,Seon-Woo Cha 한국작물학회 2007 한국작물학회 학술발표대회 논문집 Vol.2007 No.11
Objectives Here, we report the effect of overexpression of ginseng farnesyl diphosphate synthase on the transcription of three key regulatory enzymes involved in triterpene metabolism in hairy root of ginseng and Centella asiatica (L.) Urban. Materials and Methods A four-year-old root of Panax ginseng C.A. Meyer and Centella asiatica (L.) Urban whole plants were obtained from National Institute of Crop Science (Suwon, Korea) and Chonnam National University (Gwangju, Korea), respectively. Agrobacterium rhizogenes R1000 strain was kindly provided by Dr. In (Nongwoo Bio, Yeju, Korea). Results and Discussion The role of farnesyl diphosphate synthase (FPS) in triterpene biosynthesis (Fig. 1) was investigated. A pCAMBIA3101 vector was used to insert a exogenous gene into target plant genome (Fig. 2). After the transformation, we produced Panax ginseng and Centella asiatica hairy roots by introducing the coding region of the gene from Panax ginseng. In these hairy roots, integration of the transgenes into the C. asiatica nuclear genome was confirmed by PCR analysis using PgFPS (P. ginseng FPS) primers and by Southern hybridization using PgFPS-specific probe. FPS specific activity is increased 4-fold compared to controls. In RT-PCR analysis, overexpression of PgFPS in hairy roots was observed (Fig. 3) and two genes, cycloartenol and beta-amyrin synthase, related to triterpene biosynthesis were up-regulated. These results suggest that FPS overexpression might lead to an enhanced biosynthesis of triterpene saponins and phytosterols. However, we did not demonstrate whether or not the introduction of PgFPS gene in Centella asiatica genome directly enhances triterpene saponin production, although our results showed that gene expression related to triterpene saponin biosynthesis were obviously up-regulated. Therefore, additional experiments such as overexpression of FPS gene in triterpene saponin-deficient mutant plants will be required.
Correlation between Yellow Emission and Misoriented Structure in GaN Epilayers
Ok Hwan Cha,Mun Seok Jeong,고도경,Eun-Kyung Suh,Jongmin Lee,Kee Suk Nahm 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.3
A strong relationship between misoriented structure and yellow luminescence (YL) was found from the X-ray diffraction (XRD) and the photoluminescence measurements of GaN films grown by using radio-frequency induction-heated chemical vapor deposition and metal-organic chemical vapor deposition. YL was observed to be emitted from GaN films which contained peaks associated with the (10.10) and the (10.11) planes in their XRD spectra, and intensity variation of YL with some parameters, such as the growth temperature and the film thickness, had quite similar trends to that of the misoriented peak in XRD. We suggest that this tendency is due to point defects acting as YL centers trapped at the interface between the (0001) oriented structure and an unintentional structure oriented in the [10.10] and the [10.11] directions.0
Micropropagation of Hypericum erectum Thunberg by using Thidiazuron
Ok-Tae Kim,Kyong-Hwan Bang,Dong-Soo In,Tae-Soo Kim,Nak-Sul Seong,Seon-Woo Cha,Jun-Cheul Ahn,Baik Hwang 한국약용작물학회 2006 한국약용작물학회지 Vol.14 No.5
The effect of plant growth regulators was investigated on in vitro shoot proliferation from axillary bud explants of Hypericum erectum. To determine the optimal cytokinin for proliferation of axillay buds, we carried out screening four cytokinins (BA, kinetin, 2iP, TDZ). When nodal segments were cultured on MS medium supplemented with 4.5 μM TDZ (thidiazuron), a number of shoots were induced. Our results indicated that the addition of TDZ to culture medium resulted in the induction of significantly more axillary buds than in the addition of other cytokinins. The optimal concentration of TDZ for proliferation of axillary buds was 10 μM. 92% of shoots spontaneously rooted without any plant growth regulator (PGR) and formed whole plantlets within one month. More than 95% of these regenerants survived and they did not show any detectable variation in morphology or growth characteristics compared to their donor plants.
( Shin Ok Jeong ),( Eui Bae Kim ),( Soung Won Jeong ),( Jae Young Jang ),( Sae Hwan Lee ),( Sang Gyune Kim ),( Sang Woo Cha ),( Young Seok Kim ),( Young Deok Cho ),( Hong Soo Kim ),( Boo Sung Kim ),( 대한간학회 2017 Gut and Liver Vol.11 No.3
Background/Aims: To investigate the predictive factors for complete response (CR) and recurrence after CR in patients with hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE). Methods: Among 691 newly diagnosed HCC patients, 287 were treated with TACE as a first therapy. We analyzed the predictive factors for CR, recurrence after CR, and overall survival (OS). Results: Eighty-one patients (28.2%) achieved CR after TACE, and recurrence after CR was detected in 35 patients (43.2%). In multivariate analyses, tumor size (≤5 cm) and single nodularity were predictive factors for CR, with hazard ratios (HRs) of 0.35 (p=0.002) and 0.41 (p< 0.001), respectively. Elevated serum α-fetoprotein (AFP) (>20 ng/mL) level and multinodularity exhibited significant relationships with recurrence after CR, with HRs of 2.220 (p=0.026) and 3.887 (p< 0.001), respectively. Tumor size (>5 cm), multinodularity, elevated serum AFP (>20 ng/mL) level, Child-Turcotte-Pugh score (B and C), and portal vein thrombosis were significant factors for OS. Conclusions: In patients treated with TACE as a first therapy, tumor size (≤5 cm) and single nodularity were predictive factors for CR, and multinodularity and elevated serum AFP (>20 ng/mL) levels were predictive factors for recurrence after CR. These factors were also significant for OS. (Gut Liver 2017;11:409-416)
Kim, Ok-Sik,Kang, Byoung-Ho,Lee, Jae-Sung,Lee, Sang-Won,Cha, Seung-Hwan,Lee, Jun-Woo,Kim, Sae-Wan,Kim, Sang-Hyup,Kang, Shin-Won IEEE 2016 IEEE electron device letters Vol.37 No.8
<P>We propose effective charge balance CdSe/ZnS quantum dots-based light-emitting devices (QLEDs) using polyvinyl pyrrolidone (PVP)-capped ZnO nanoparticles (NPs) synthesized by sol-gel process as electron transport layer. In general, ZnO NPs have a trap-site induced from oxygen vacancies. An oxygen vacancy captures electrons and reduces the performance of QLEDs. In order to reduce the oxygen vacancies and improve performance, we used PVP for modifying the surface of ZnO NPs. This modification significantly enhanced the luminance and current efficiency of the resulting PVP-capped ZnO NPs-based QLEDs to more than 1.5 times of their values in uncapped ZnO NPs-based QLEDs.</P>