• Journal of Ecology and Environment
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• 제30권3호
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• pp.257-264
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• 2007

Over-expression of a copper/zinc superoxide dismutase (Cu/ZnSOD) resulted in substantially increased tolerance to cadmium exposure in Arabidopsis thaliana. Lower lipid peroxidation and $H_2O_2$ accumulation and the higher activities of $H_2O_2$ scavenging enzymes, including catalase (CAT) and ascorbate peroxidase (APX) in transformants (CuZnSOD-tr) compared to untransformed controls (wt) indicated that oxidative stress was the key factor in cadmium tolerance. Although progressive reductions in the dark-adapted photochemical efficiency (Fv/Fm) and quantum efficiency yield were observed with increasing cadmium levels, the chlorophyll fluorescence parameters were less marked in CuZnSOD-tr than in wi. These observations indicate that oxidative stress in the photosynthetic apparatus is a principal cause of Cd-induced phytotoxicity, and that Cu/ZnSOD plays a critical role in protection against Cd-induced oxidative stress.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.23-29
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• 2022

To improve spectrum and energy efficiency in the fifth generation (5G) wireless channels, intelligent reflecting surface (IRS) transmissions have been envisioned, possibly towards the sixth generation (6G) networks. In this paper, we analyze the bit-error rate (BER) performance of intelligent reflecting surface (IRS) assisted non-orthogonal multiple access (NOMA) systems. First, we derive a closed-form expression of the BER in terms of Q functions. Then we analyze the BER improvement of the IRS NOMA system over the conventional NOMA system with respect to the power allocation. Furthermore, we also demonstrate numerically the BER improvement of the IRS NOMA network over the conventional NOMA network in respect of the number of reflecting devices.

• ETRI Journal
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• 제29권6호
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• pp.707-715
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• 2007

In-phase/quadrature (I/Q) imbalances, which are generated by non-ideal transceiver components, are inevitable physical phenomena that cause the performance of practical communication systems to be degraded. In this paper, we provide a new closed-form expression for the bit error rate of hierarchical M-ary phase shift keying with I/Q phase and amplitude imbalances and analyze the effect of I/Q imbalances on BER performance over an additive white Gaussian noise channel.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2023년도 춘계학술대회
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• pp.130-130
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• 2023

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.3583-3587
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• 2012

SUMOylation has emerged as an important post-translational modification that modulates the localization, stability and activity of a broad spectrum of proteins. A dynamic process, it can be reversed by a family of SUMO-specific proteases (SENPs). However, the biological roles of SENPs in mammalian development and pathogenesis remain largely elusive. Here, we demonstrated that SENP2 plays a critical role in the control of hepatocellular carcinoma cell growth. SENP2 was found to be down-regulated in hepatocellular carcinoma (HCC) tissues and over-expression suppressed the growth and colony formation of HCC cells. In contrast, silencing of SENP2 by siRNAs promoted cancer cell growth. We further found that stability of ${\beta}$-catenin was markedly decreased when SENP2 was over-expressed. Interestingly, the decrease was dependent on the de-SUMOylation activity of SENP2, because over-expression of a SENP2 catalytic mutant form had no obviously effects on ${\beta}$-catenin. Our results suggest that SENP2 might play a role in hepatocellular carcinoma cell growth control by modulating the stability of ${\beta}$-catenin.

• Molecules and Cells
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• 제27권3호
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• pp.299-305
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• 2009

Over-expression of phospholipase D (PLD) 1 or PLD2 down-regulated CKII activity in NIH3T3 cells. The same results were found with catalytically inactive mutants of PLD isozymes, indicating that the catalytic activity of PLD is not required for PLD-mediated CKII inhibition. Consistent with this, 1-butanol did not alter CKII activity. The reduction in CKII activity in PLD-over-expressing NIH3T3 cells was due to reduced protein level, but not mRNA level, of the $CKII{\beta}$ subunit. This PLD-induced $CKII{\beta}$ degradation was mediated by ubiquitin-proteasome machinery, but MAP kinase and mTOR were not involved in $CKII{\beta}$ degradation. PLD isozymes interacted with the $CKII{\beta}$ subunit. Immunocytochemical staining revealed that PLD and $CKII{\beta}$ colocalize in the cytoplasm of NIH3T3 cells, especially in the perinuclear region. PLD binding to $CKII{\beta}$ inhibited $CKII{\beta}$ autophosphorylation, which is known to be important for $CKII{\beta}$ stability. In summary, the current data indicate that PLD isozymes can down-regulate CKII activity through the acceleration of $CKII{\beta}$ degradation by ubiquitin-proteasome machinery.

• Journal of Korean Neurosurgical Society
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• 제53권6호
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• pp.323-330
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• 2013

Objective : To develop a simple, reproducible model of disc degeneration in rabbits through percutaneous annular puncture and to confirm the degree of degeneration over time. Methods : Fifteen New Zealand white rabbits (4 to 5 months old and weighing approximately 3 to 3.5 kg each) underwent annular puncture of the L2-L3, L3-L4, and L4-L5 discs. Rabbits were sacrificed at 4, 8, or 20 weeks after puncture. For a longitudinal study to assess changes in disc height over time, serial X-rays were performed at 0, 2, 4, 8, and 20 weeks for rabbits in the 20-week group. Upon sacrifice, the whole spinal column and discs were extracted and analyzed with magnetic resonance imaging (MRI), real time reverse transcriptase-polymerase chain reaction, and histological staining. Results : The X-rays showed a slow, progressive decrease in disc height over time. Significant disc space narrowing compared to preoperative disc height was observed during the time period (p<0.001). The MRI grade, aggrecan, and matrix metalloprotease-13 mRNA expression and hematoxylin and eosin/safranin O/anti-collagen II staining were consistently indicative of degeneration, supporting the results of the X-ray data. Conclusion : Percutaneous annular puncture resulted in slow, reproducible disc degeneration that was confirmed by radiology, biochemistry, and histology. This in vivo model can be used to study and evaluate the safety and efficacy of biologic treatments for degenerative disc disease.

• 한국정보과학회논문지:소프트웨어및응용
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• 제37권1호
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• pp.1-8
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• 2010

최근 마이크로어레이 데이터를 기반으로 두 개의 샘플 그룹간에 유의한 발현 차이를 나타내는 생물학적 기능 그룹을 검출하기 위한 유전자 집합 분석(gene set analysis) 연구가 많은 주목을 받고 있다. 기존의 유의 유전자 검출 연구와는 달리, 유전자 집합 분석 연구는 유의한 유전자 집합과 이들의 기능적 특징을 함께 검출할 수 있다는 장점이 있다. 이러한 이유로 최근에는 PAGE, GSEA 등과 같은 다양한 통계적 방식의 유전자 집합 분석 방법들이 소개되고 있다. 특히, PAGE의 경우 두 샘플 그룹간의 유전자 발현 차이를 나타내는 스코어의 분포가 정규 분포임을 가정하는 모수적 접근 방식을 취하고 있다. 이러한 방법은 GSEA 등과 같은 비모수적 방식에 비해 계산량이 적고 성능이 비교적 우수한 장점이 있다. 하지만, PAGE에서 유전자 발현 차이를 정량화하기 위한 메트릭으로 사용하고 있는 AD(average difference)의 경우, 두 그룹간에 절대적 평균 발현 차이만을 고려하기 때문에 실제 유전자의 발현값 크기나 분산의 크기에 따른 상대적 중요성을 반영하지 못하는 문제가 있다. 본 논문에서는 이를 보완하기 위해 실제 유전자의 발현값 크기나 그룹 내 샘플들의 분산 정보 등을 스코어 계산에 함께 반영하는 WAD(weighted average difference), FC(Fisher's criterion), 그리고 Abs_SNR(Absolute value of signal-to-noise ratio)을 모수적 방식의 유전자 집합 분석에 적용하고 이에 따른 유의 유전자 집합 검출 결과를 실험을 통해 비교 분석하였다.

• BMB Reports
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• 제42권11호
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• pp.752-757
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• 2009

Copper is essential but toxic in excess for aerobic organisms. Yeast transcription factor ACE1 functions as a sensor for copper and an inducer for the transcription of CUP1. In addition, ACE1 can activate the transcription of superoxide dismutase gene (sod1) in response to copper. In this study, we introduced the yeast ACE1 into Arabidopsis and analyzed its function in plant. Under high copper stress, the transgenic plants over-expressing ACE1 showed higher survival rate than the wild-type. We also found that over-expression of ACE1 in Arabidopsis increased the activities of SOD and POD, which were beneficial to the cell in copper buffering. Excess copper would suppress the expression of chlorophyll biosynthetic genes in Arabidopsis, RT-PCR analysis revealed that over-expression of ACE1 decrease the suppression. Together, our results indicate that ACE1 may play an important role in response to copper stress in Arabidopsis.

• 미생물학회지
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• 제46권4호
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• pp.401-404
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• 2010

출아효모 Saccharomyces cerevisiae에서 RNA-binding 단백질인 Tho1은 mRNA가 전사되는 동안 초기 mRNA에 결합하여 mRNP 생성과 성숙한 mRNA의 핵에서 세포질로의 방출에 관여하는 것으로 여겨진다. 분열효모 Schizosaccharomyces pombe에서도 Tho1과 유사한 단백질을 암호화하는 유전자(spTho1로 명명)를 찾아 그 특성을 조사하였다. 이배체 S.pombe 균주에 하나의 spTho1 유전자만을 결실시킨 후 4분체분석을 수행한 결과, 이 유전자는 생장에 반드시 필요하지 않았다. 또한 spTho1 결실 돌연변이는 mRNA의 핵에서 세포질로의 방출도 정상적으로 보였다. 그러나 티아민에 의해 발현이 조절되는 강력한 프로모터를 이용하여 spTho1를 과발현시키면, 세포의 생장이 억제되었으며 $poly(A)^+$ RNA가 핵 안에 축적되었다. 이와 같은 결과들은 spTho1 유전자가 필수적이지는 않지만 mRNA의 핵에서 세포질로의 방출에 관여하고 있음을 시사한다.