• BMB Reports
• /
• 제43권12호
• /
• pp.813-817
• /
• 2010

Plants undergo cell division throughout their life in order to maintain their growth. It is well known that root and shoot tip of plants possess meristems, which contain quiescent cells. Fluridone (1-methyl-3-phenyl-5-(3-trifluromethyl (phenyl))-4-(1H)-pyridinone) is an established inhibitor of both ABA and carotenoid biosynthesis. However, the other functions of fluridone remain undiscovered. In this report, we provide experimental evidence that fluridone plays a role in the division of the quiescent centre of the Arabidopsis root meristem. This study examined the effects of exogenous fluridone and ABA on the development of the stem cell niche in Arabidopsis root. We show that fluridone promoted the division of stem cells in the quiescent centre, whereas exogenous ABA suppressed quiescent centre division. Furthermore, we established a novel regulatory function for fluridone by demonstrating that it plays an important role in postembryonic development.

• 한국통신학회논문지
• /
• 제34권5A호
• /
• pp.421-428
• /
• 2009

Inter-cell coordination has been an emerging issue for mitigating inter-cell interference in broadband wireless access networks such as IEEE802.16 and 3GPP LTE (Long Term Evolution). This paper proposes uplink/downlink hybrid inter-cell coordination patterns for a TDD (Time Division Duplex)/MC-CDMA (Multi-Carrier Code Division Multiple Access) system. For the performance analysis, closed forms of inter-cell interferences are derived when uplink and downlink transmissions coexist over a multi-cell environment. In the analysis, we find an optimal ratio of downlink transmit powers of BSs (Base Stations) based on the target outage probability and the performance according to ratios of uplink/downlink transmit powers of MSs (Mobile Stations)/BSs is explored. Our numerical results show that interference mitigation utilizing the characteristics of the uplink and downlink power ratio is very effective in improving system performance in terms of QoS.

• Journal of Information Processing Systems
• /
• 제15권1호
• /
• pp.47-54
• /
• 2019

This study is concerned with the mechanism and structure of an optical microscope and an automatic multi-focus algorithm for automatically selecting sharp images from multiple foci of a cell. To obtain precise cell images quickly, a z-axis actuator with a resolution of $0.1{\mu}m$ was designed to control an optical microscope Moreover, a lighting control system was constructed to select the color and brightness of light that best suit the object being viewed. Cell images are captured by the instrument and the sharpness of each image is determined using Gaussian and Laplacian filters. Next, cubic spline interpolation and peak detection algorithms are applied to automatically find the most vivid points among multiple images of a single object. A cancer cell imaging experiment using propidium iodide staining confirmed that a sharp multipoint image can be obtained using this microscope. The proposed system is expected to save time and effort required to extract suitable cell images and increase the convenience of cell analysis.

• Journal of Animal Science and Technology
• /
• 제63권5호
• /
• pp.977-983
• /
• 2021

Closely correlated expression patterns between ubiquitin specific peptidase 9X-linked (USP9X) and adherens junction formation factor (Afadin) in mouse testis development suggests that Usp9x regulates the deubiquitination of Af-6 (also known as Afadin, AFDN), and subsequently, the cell adhesion dynamics during gametogenesis. However, this relationship has not yet been tested in other domestic animals. The study was examined the temporal and spatial expression patterns of porcine USP9X and AFDN from the pre-pubertal to adult stages using real time-PCR and immunohistochemistry. Furthermore, we detected the transcripts of USP9X and AFDN in the testis of 1-, 6- and 12-months old boar, respectively. USP9X and AFDN were found to have similar expressions patterns, with basal expression after 1 month followed by a significant up-regulation from 6 months (puberty) onwards. In addition, neither the AFDN or USP9X proteins were detected in spermatogenic cells but they were expressed in the leydig cells and sertoli cells. USP9X was detected around the basal lamina during pre-puberty, and predominantly expressed in the leydig cells at puberty. Finally, in adult testis, USP9X was increased at the sertoli cell-cell interface and the sertoli cell-spermatid interface. In summary, closely correlated expression patterns between USP9X and AFDN in boar testis supports the previous findings in mice. Furthermore, the junction connections between the sertoli cells may be regulated by the ubiquitination process mediated via USP9X.

• Journal of Microbiology and Biotechnology
• /
• 제12권1호
• /
• pp.121-129
• /
• 2002

Using recombinant Chinese hamster ovary (CHO) cells, strategies for developing high producers for the recombinant human Transforming Growth $Factor-{\beta}1$ ($TGF-{\beta}1$) protein are proposed and their physiological characteristics in cell cultures were investigated. $TGF-{\beta}1$ is a pleiotrophic polypeptide involved in various biological activities, including cell growth, differentiation, and deposition of extracellular matrix proteins. The CHO cells included human $TGF-{\beta}1$ cDNA in conjunction with a dihydrofolate reductase (DHFR) gene, which was cotransfected into the cells to amplify the transfected $TGF-{\beta}1$ cDNA. As a first-round screening of the transfected cells, a relatively high $TGF-{\beta}1$-producing cell line was selected, and then, it acquired a resistance to increasing concentrations of methotrexate (MTX) up to $60{\mu}M$,resulting in a significant improvement in its $TGF-{\beta}1$ biosynthetic ability. After applying a monoclonal selection strategy to the MTX-resistant cells, more productive cells were screened, including the APP-3, App-5, and App-8 cell lines. These high producers were compared with two other cell lines (AP-l cell line without amplification of transfected $TGF-{\beta}1$ cDNA and nontransfectant of $TGF-{\beta}1$ cDNA) in terms of cell growth, $TGF-{\beta}1$ productivity, sugar uptake, and byproduct formation, in the presence or absence of MTX in the culture medium. Consequently, both monoclonal selection as well as an investigation of the physiological characteristics were found to be needed for the efficient screening of higher $TGF-{\beta}1$ producers, even after the transfection and amplification of the transfected gene.

• 한국항행학회논문지
• /
• 제15권4호
• /
• pp.562-570
• /
• 2011

본 논문에서는 이동성을 갖춘 릴레이를 도입한 다중 셀 OFDM (Orthogonal Frequency Division Multiplexing)-TDD (Time Division Duplex) 시스템에서 각 셀의 수율을 개별적으로 최대화시키기 위한 분산형 이동 릴레이 전력 제어 방식 (Distributed Mobile Relay Power Control; DMRPC)을 제안한다. DMRPC 방식을 사용한 릴레이 시스템에서는 서로 다른 셀 간 협력과 그에 따른 시그널링 오버헤드 없이 각 셀에서 개별적으로 릴레이의 전력 레벨을 제어한다. DMRPC 방식을 사용한 시스템이 전력 제어 없이 릴레이를 사용한 최대 전력 릴레이 시스템과, 릴레이를 사용하지 않은 기존 시스템에 비하여 향상된 셀 수율 성능을 보이는 것을 모의 실험을 통하여 검증한다. 또한, 최대 전력 릴레이 시스템이 기존 시스템에 비해 셀 외곽 지역 평균 수율 성능이 떨어지는 반면, DMRPC 방식을 사용하면 기존 시스템에 거의 근접한 셀 외곽 지역 평균 수율 성능을 얻을 수 있는 것을 보인다.

• Molecules and Cells
• /
• 제37권6호
• /
• pp.497-502
• /
• 2014

Microfluidics can provide unique experimental tools to visualize the development of neural structures within a microscale device, which is followed by guidance of neurite growth in the axonal isolation compartment. We utilized microfluidics technology to monitor the differentiation and migration of neural cells derived from human embryonic stem cells (hESCs). We co-cultured hESCs with PA6 stromal cells, and isolated neural rosette-like structures, which subsequently formed neurospheres in suspension culture. Tuj1-positive neural cells, but not nestin-positive neural precursor cells (NPCs), were able to enter the microfluidics grooves (microchannels), suggesting that neural cell-migratory capacity was dependent upon neuronal differentiation stage. We also showed that bundles of axons formed and extended into the microchannels. Taken together, these results demonstrated that microfluidics technology can provide useful tools to study neurite outgrowth and axon guidance of neural cells, which are derived from human embryonic stem cells.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.413-413
• /
• 2012

Lead sulfide (PbS) Colloidal quantum dots (CQDs) are promising material for the photovoltaic device due to its various outstanding properties such as tunable band-gap, solution processability, and infrared absorption. More importantly, PbS CQDs have large exciton Bohr radius of 20 nm due to the uniquely large dielectric constants that result in the strong quantum confinement. To exploit desirable properties in photovoltaic device, it is essential to fabricate a device exhibiting stable performance. Unfortunately, the performance of PbS NQDs based Schottky solar cell is considerably degraded according to the exposure in the air. The air-exposed degradation originates on the oxidation of interface between PbS NQDS layer and metal electrode. Therefore, it is necessary to enhance the stability of Schottky junction device by inserting a passivation layer. We investigate the effect of insertion of passivation layer on the performance of Schottky junction solar cells using PbS NQDs with band-gap of 1.3 eV. Schottky solar cell is the simple photovoltaic device with junction between semiconducting layer and metal electrode which a significant built-in-potential is established due to the workfunction difference between two materials. Although the device without passivation layer significantly degraded in several hours, considerable enhancement of stability can be obtained by inserting the very thin LiF layer (<1 nm) as a passivation layer. In this study, LiF layer is inserted between PbS NQDs layer and metal as an interface passivation layer. From the results, we can conclude that employment of very thin LiF layer is effective to enhance the stability of Schottky junction solar cells. We believe that this passivation layer is applicable not only to the PbS NQDs based solar cell, but also the various NQDs materials in order to enhance the stability of the device.

• 한국전자파학회논문지
• /
• 제20권1호
• /
• pp.91-99
• /
• 2009

본 논문에서는 micro-TEM cell을 사용한 표준 전자기장 발생법을 기술하고 측정불확도를 평가하였다. 표준 전자기장 발생 시스템은 auto-leveling 기능을 가진 신호발생부, 최대 1.2 GHz까지 동작하는 micro-TEM cell, 서미스터 마운트를 사용한 전력측정부로 구성된다. 표준 전자기장 발생법의 타당성을 보이기 위해 $10\;MHz{\sim}1\;GHz$ 대역에서 전자기장의 세기 20 V/m에 대해 실시된 전자기장의 세기 국제비교(CCEM.RF-K20)의 참여 결과를 제시하였다.

• 한국동물번식학회:학술대회논문집
• /
• 한국동물번식학회 2001년도 춘계학술발표대회
• /
• pp.66-66
• /
• 2001

Since the first birth of pig derived from embryonic cells by nuclear transfer, many researches to produce cloned pig have been carried out. Recently, two reports about the birth of somatic cell cloned pigs using in vivo oocytes and also Betthauser et al. (2000) reported the birth of somatic cell cloned pigs using in vitro oocytes. So here we investigated the effect of activation method and culture medium on in vitro development of porcine nuclear transfer embryo using fetal fibroblast. Oocytes derived from slaughter house obtained ovaries were matured for 42 to 44 h in TCM 199. Matured oocytes were denuded using 0.1% hyaluronidase and then Oocytes with the first polar body were used for enucleation by aspirating the first polar body and adjacent cytoplasm in TCM 199 supplemented with 7.5 $\mu\textrm{g}$ cytochalasin B. Petal fibroblast cells were prepared from 35 days old fetus. To be used as donor cells, fetal fibroblast cells were serum starved for 3 to 5 days and then isolated into single co:1 by trypsinization. Nuclear transfer embryos were fused using 2 times 1.25㎸ for 30$mutextrm{s}$. Fused NT embryos were activated with calcium ionophore (CI) and 6-dimethyl-aminopurine (6-DMAP). Activated oocytes were cultured in NCSU 23 or BECM 3 for 6 days. There was no significant difference between chemical activation and no chemical activation for blastocyst development rate(11.6 vs. 14.8%). However, cell number was significantly higher when NT embryos were activated with CI and 6-DMAP (31.2 vs. 22.6). When NT embryos were cultured in NCSU 23 or BECM 3, blastocyst development rate was 16.4 and 13.2%, respectively, and cell number was 31.5 and 24.1, respectively. These results suggest that chemical activation after fusion and culture in NCSU 23 could increase cell number of porcine NT embryos.