• 식물분류학회지
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• 제37권4호
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• pp.351-361
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• 2007

In angiosperms, leaves typically develop as three-dimensional structure with dorsoventral, longitudinal, and lateral axes. We have shown that the control of two axes of leaves, longitudinal and lateral axis, can be genetically separable, and four classes of genes are responsible for the polar cell expansion and polar cell proliferation in Arabidopsis. In monocots, unifacial leaf, in which leaf surface consists only of abaxial identity, has been evolved in a number of divergent species. The unifacial leaves provide very unique opportunities for the developmental studies of the leaf axes formation in monocots, because their leaf polarities are highly disorganized. In addition, the mechanism of the parallel evolution of such drastic changes in leaf polarities is of interest from an evolutionary viewpoint. In this article, we describe our recent approaches to reveal the mechanism of unifacial leaf development and evolution, including recent advances in the leaf polarity specification in angiosperms.

• 식물분류학회지
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• 제38권1호
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• pp.51-61
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• 2008

잎은 무한생장기관으로 잎의 극성제어에 많은 유전적인 요소가 필요하다. 이들 극성은 잎의 초기발생과정에서 제어되기 시작하고, 정단분열조직과 잎기관의 원기와의 제어를 담당하는 인자들에 의해서 결정이 된다. 본 연구에서는 가늘고 바늘처럼 생긴 잎을 가진 deformed root and leaf1 (drl1) 돌연변이체를 유전학적 해석하였고, 그 결과 DRL1 유전자는 정단분열조직과 잎의 극성축을 제어하고 있는 것으로 판명되었다. 이 DRL1 유전자는 효모의 KTI12 유전자 산물과 유사한 단백질인 Elongator associate protein을 만들어 내는 것으로 판명되었다. 또한, 이 단백질의 아미노산 서열이 원핵생물에서부터 진핵생물까지 광범위하게 진화적으로 보존되고 있는 것으로 밝혀졌다. 특히, DRL1 단백질과 유사한 식물의 단백질은 계통해석 결과 단일계통을 나타내고 있는 것으로 나타났고, 이는 이 단백질들이 육상식물의 진화과정에서 잘 보존되고 있음을 시사하고 있다.

• Molecules and Cells
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• 제38권3호
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• pp.243-250
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• 2015

Patterning of the polar axis during the early leaf developmental stage is established by cell-to-cell communication between the shoot apical meristem (SAM) and the leaf primordia. In a previous study, we showed that the DRL1 gene, which encodes a homolog of the Elongator-associated protein KTI12 of yeast, acts as a positive regulator of adaxial leaf patterning and shoot meristem activity. To determine the evolutionally conserved functions of DRL1, we performed a comparison of the deduced amino acid sequence of DRL1 and its yeast homolog, KTI12, and found that while overall homology was low, well-conserved domains were presented. DRL1 contained two conserved plant-specific domains. Expression of the DRL1 gene in a yeast KTI12-deficient yeast mutant suppressed the growth retardation phenotype, but did not rescue the caffeine sensitivity, indicating that the role of Arabidopsis Elongator-associated protein is partially conserved with yeast KTI12, but may have changed between yeast and plants in response to caffeine during the course of evolution. In addition, elevated expression of DRL1 gene triggered zymocin sensitivity, while overexpression of KTI12 maintained zymocin resistance, indicating that the function of Arabidopsis DRL1 may not overlap with yeast KTI12 with regards to toxin sensitivity. In this study, expression analysis showed that class-I KNOX genes were downregulated in the shoot apex, and that YAB and KAN were upregulated in leaves of the Arabidopsis drl1- 101 mutant. Our results provide insight into the communication network between the SAM and leaf primordia required for the establishment of leaf polarity by mediating histone acetylation or through other mechanisms.

• Molecules and Cells
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• 제19권3호
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• pp.342-349
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• 2005

Cytokinins are adenine derivatives that regulate numerous plant growth and developmental processes, including apical and floral meristem development, stem growth, leaf senescence, apical dominance, and stress tolerance. However, not much is known about how cytokinin biosynthesis and metabolism is regulated. We identified a novel Arabidopsis gene, ALL, encoding an aldolase-like enzyme that regulates cytokinin signaling. An Arabidopsis mutant, all-1D, in which ALL is activated by the nearby insertion of the 35S enhancer, exhibited extreme dwarfism with rolled, dark-green leaves and reduced apical dominance, symptomatic of cytokinin-overproducing mutants. Consistent with this, ARR4 and ARR5, two representative primary cytokinin-responsive genes, were significantly induced in all-1D. Whereas SHOOT MERISTEMLESS (STM) and KNAT1, which regulate meristem development, were also greatly induced, expression of REV and PHV that regulate lateral organ polarity was inhibited. ALL encodes an aldolase-like enzyme that belongs to the HpcH/HpaI aldolase family in prokaryotes and is down-regulated by exogenous cytokinin, possibly through a negative feedback pathway. We propose that ALL is involved in cytokinin biosynthesis or metabolism and acts as a positive regulator of cytokinin signaling during shoot apical meristem development and determination of lateral organ polarity.

• Journal of Forest and Environmental Science
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• 제18권1호
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• pp.1-6
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• 2001

본 연구는 음나무의 증식을 위해 근삽을 이용하여 대량번식방법의 체계를 확립하고자 실시하였다. 조사된 결과는 다음과 같다. 1. 음나무의 근삽시 생장조절물질의 처리는 고농도보다 저농도가 효과적인 것으로 나타났으며, 생장조절물질 처리에 따른 부정아 발생율은 IBA, NAA 300mg/L 처리구에서 96.6%로 가장 높게 나타났으나 무처리 역시 90.0%로 높은 부정아 발생율을 나타내었다. 또한 엽의 특성(엽수, 엽신, 엽폭)은 무처리와 생장조절물질 처리간에 큰 차이를 나타내지 않았다. 2. 근의 방향에 따른 근삽은 가로근삽(100%)과 세로근삽 (92.5%) 이 모두 90% 이상의 부정아 발생율을 보여 두 처리 모두 높은 부정아 발생율을 나타내었고, 부정아 발생수 및 엽 특성(엽수, 엽병, 엽신 및 엽폭)에 있어서 세로근삽이 가로근삽보다 모두 높게 나타났다. 3. 바로묻기 한 것이 거꾸로묻기 한 것보다 부정아 발생율, 부정아 발생수 및 엽특성(엽수, 엽신, 엽폭)에서 높은 값을 나타냈으며, 거꾸로묻기 한 경우 세근의 발달이 없거나 미약하며, 부정아 발생의 경우 기극 부근에서 발생하여 지면으로 올라오는 경우를 나타냈다.

• Journal of Plant Biotechnology
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• 제3권1호
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• pp.19-25
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• 2001

Induction of somatic embryogenesis from Brazilian eggplant variety F-100 was studied in response to four auxin types. NAA, at the optimal concentration of 54 $\mu\textrm{m}$, was the only one that resulted in the induction of somatic embryos in either leaf and cotyledon explant and, at murk lower intensity and frequency, in hypocotyl and epicotyl explants. The optimal temperatures for embryo induction were 28 and 35$^{\circ}C$ for cotyledon and leaf explants. Incubation at 22$^{\circ}C$ caused a significant reduction both in the frequency and intensity of induction. This system was used to study the effects of position and orientation of the tissue on the culture medium as well as of antibiotics and explant co-cultivation with Agrobacterium on the efficiency of somatic embryo induction. The intensity of embryo induction was greater in the midsections of cotyledons relative to apical and basal regions, when the abaxial surface was in contact with the culture medium. The presence of antibiotics resulted in approximately 40-60% reduction of embryo induction relative to control explants, which originated 335$\pm$26.6 embryos. Co-cultivation with Agrobacterium before treatment with antibiotics caused a more drastic reduction (80-99%). Ampicilin treatment after cocultivalion with Agrobacterium caused the least inhibitory effect, allowing the production of 60 embryos/explant.

• Progress in Superconductivity
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• 제4권2호
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• pp.109-113
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• 2003

We have developed a planar-type single layer second-order $high-T_{c}$ SQUID gradiometer, which can detect the $d^2$$B_{z/}$dxdy of the second-order field gradient. This SQUID gradiometer consists of four-way 'clover-leaf' pick-up loops and is coupled directly to a 4-junction dc SQUID in such a way that the coupling polarity of the two diagonal loops is opposite to that of the other two loops. The pickup loops are intrinsically balanced for both uniform field and the 1 st-order field gradient. The $YBa_2$$Cu_3$$O_{7}$ thin film was made by pulsed laser deposition method on $SrTiO_3$ single crystal substrate and patterned by photolithography with Ar ion milling technique. Response of this gradiometer was tested for both uniform field and the 2nd-order field gradient. Details of the design, fabrication, and results will be discussed.

• 한국작물학회지
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• 제46권4호
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• pp.309-316
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• 2001

Helianthus tuberosus has been known to inhibit the growth of weeds and other plants sharing its habitat. This study was conducted to identify the allelochemicals of Helianthus tuberosus which were extracted with water and solvents. Aqueous extracts of leaf, stem, root, tuber and tuber peel of Helianthus tuberosus except tuber did not show significant differences in phytotoxicity to alfalfa seedlings. It was considered that Helianthus tuberosus contained fewer or less potential water-soluble substances that were toxic to alfalfa. Methanol extract of leaves of Helianthus tuberosus was sequentially partitioned in increasing polarity with n-hexane, ethylacetate and n-butanol. Each extract had a yield of 148, 12, 15.7 and 9.5g, respectively. Inhibitory effects on germination of alfalfa seeds treated with four fractions were not significantly different. But the significant reductions on hypocotyl length were observed for all the solvent extracts. Among the four fractions, the ethylacetate fraction showed the most significant inhibition effect on bioassay with alfalfa. Further separation of the active ethylacetate fraction by open column chromatography led to the 25 subfractions. In bioassay of each sub-fraction with alfalfa seeds, sub-fraction No. 13 showed the most inhibitory effect on seedling growth. $^1$H NMR and gas chromatography-mass spectrometry analysis revealed that sub-fraction No. 13 was the mixture of straight-chain saturated fatty acids.

• Natural Product Sciences
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• 제28권3호
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• pp.130-137
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• 2022

This study was conducted to characterise phytochemicals and to explore the biological activities of Vitex negundo leaves. The washed, course powder of V. negundo leaves were extracted with different solvents of increasing polarity. All the extracts were characterized and biological activities were compared. The results revealed that the ethanolic and cold water extracts showed the presence of all phytochemicals studied except protein compared to other extracts. Further, the quantitative estimation of phytochemicals showed that the ethanolic extract had highest yield and maximum amount of total polyphenols, flavonoids, and alkaloids with the least amount of tannins compared to other extracts studied. Furthermore, the highest total polyphenol content corresponds with the potent biological activities. Indeed, in vitro antioxidant and antisteroidogenic activities were highest in the ethanolic extract than others. To conclude, the present study is the first to report the characterization and antiandrogenic property of V. negundo leaf extracts. The ethanolic extract of V. negundo leaves can be used as an antioxidant and antiandrogenic agent. Hence, it can be considered for the treatment of hyperandrogenic conditions like polycystic ovary syndrome, etc.

• 한국잡초학회지
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• 제17권4호
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• pp.407-412
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• 1997

약용작물의 allelopathy 효과를 구명하기 위하여 메탄올 추출물을 이용하여 생물검정한 결과 피의 발아, 신초 및 뿌리생육 억제는 공시식물, 사용부위, 사용농도에 따라 다르게 나타났는데 피의 발아, 신초 생장 및 뿌리는 천궁 및 감초 뿌리추출물에 의해서 가장 억제가 되었다. 1g 농도에서 피의 발아, 신초생장, 뿌리생장이 각각 88%, 95%, 100%, 감초추출물에서 87%, 96%, 100% 억제되었다. 천궁의 부위별 억제정도는 뿌리에서 가장 크게 나타났는데 0.5g에서 피는 완전히 억제가 되었으나 줄기 잎추출물에서는 억제효과가 크지 않았다. 용매극성별 피의 억제 정도는 에틸아세테이트에서 가장 크게 억제되었다. 피의 발아는 3분획 모두 억제가 되지 않았으나 신초 및 뿌리생장은 에틸아세테이트분획이 에틸에테르나 메탄올 분획보다 억제가 더 컸다. 이상의 결과에서 천궁뿌리에 함유하고 있는 allelochemicals은 중간정도의 극성을 띤 물질일 것으로 사료되며 allelochemicals의 분리정제에 귀중한 재료가 될 것으로 사료된다.