• Applied Microscopy
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• 제35권1호
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• pp.15-22
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• 2005

진핵세포 내에 존재하는 metallothionein (MT)은 시스테인 함량이 높은 저분자량의 단백질로서 2가 금속이온들과의 친화력이 높아 중금속에 대한 해독작용, 금속이온의 대사 및 세포분열 등과 관련되어 있다. 본 연구자들은 간 재생능력이 우수한 흰쥐를 실험모델로 하여, 간의 70% 정도를 실험적으로 제거한 후, 간 재생을 유도하는 과정에서 시간 경과에 따라 간세포의 미세구조 변화와 더불어 MT 유전자 발현 및 이 단백질의 세포내 분포를 알아보고자 하였다. 부분 간 절제 후 간 조직이 증식되고 재구성되어 간이 원래의 크기로 재생되는 시간은 1주일 정도가 소요되었다. 재생중인 간세포는 핵대 세포질의 비가 크고, 핵내에 인이 크게 발달하고 크기가 작은 미토콘드리아가 다수 나타났으며, 조면소포체가 잘 발달하고 있었다. MT mRNA는 간 절제 직후부터 증가하기 시작하여 1시간 경과 후에 최대치에 이르렀고, 12시간 이후부터 감소하기 시작하였다. 재생중인 간세포에서 MT에 대한 면역반응은 간 절제 후 12시간이 경과한 군에서 가장 높게 나타났고, 이후 점차 감소하여 8일이 경과한 실험군에서는 정상 대조군과 유사한 정도로 감소하는 것으로 관찰되었다. 또한, 간 재생 초기에는 항-MT 금 입자들이 주로 세포질쪽에 분포하다가 점차 핵내에 존재하는 양이 증가하는 것으로 나타났다. 이러한 결과들은 간 절제 후 보상작용으로 일어나는 세포분열 단계에서 MT가 이 과정에 필요한 요소를 제공하는 역할을 수행하기 때문인 것으로 사료된다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권7호
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• pp.3409-3416
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• 2012

Aim: It is well known that polycyclic aromatic hydrocarbons (PAHs) such as benzo (a) pyrene have carcinogenic properties and may cause many types of cancers in human populations. Genetic susceptibility might be due to variation in genes encoding for carcinogen metabolizing enzymes, such as cytochrome P-450 (CYP450). Our study aimed to investigate the effect of genetic polymorphisms of CYP1A1 (m1 and m2) on genetic damage in 115 coal-tar workers exposed to PAHs at their work place. Methods: Genetic polymorphisms of CYP1A1 were determined by the PCR-RFLP method. Comet and buccal micronucleus assays were used to evaluate genetic damage among 115 coal tar workers and 105 control subjects. Results: Both CYP1A1 m1 and CYP1A1 m2 heterozygous and homozygous (wt/mt+mt/mt) variants individually as well as synergistically showed significant association (P<0.05) with genetic damage as measured by tail moment (TM) and buccal micronuclei (BMN) frequencies in control and exposed subjects. Conclusion: In our study we found significant association of CYP1A1 m1 and m2 heterozygous (wt/mt)+homozygous (mt/mt) variants with genetic damage suggesting that these polymorphisms may modulate the effects of PAH exposure in occupational settings.

• Journal of Plant Biotechnology
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• 제5권1호
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• pp.33-41
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• 2003

Microspore-derived cell lines resistant to 5-methyltryptophan (5MT, a tryptophan analog) or S-(2-aminoethyl)-L-cysteine (AEC, a Iysine analog) were selected in rice by in vitro mutagenesis. For selection of 5MT or AEC resistant cell lines, suspension-cultured cells were irradiated with gamma rays. Thirteen 5MT resistant cell lines were selected and they were able to grow stably at 2 times higher 5MT concentration. A feedback insensitive form of anthranilate synthesis, the pathway specific control enzyme for tryptophan synthesis, was detected from the 5MT resistant lines. Contents of the free amino acids in five resistant lines (MR12-1 to MR12-5) showed a 7.4 to 46.6 times greater level than that in the control culture. Tryptophan, phenylalanine, and tyrosine levels in the shikimate pathway were 28.1 and 22.5 times higher in MR12-3 and MR12 4, respectively, than that measured in the control cells. Four AEC resistant cell lines were isolated from cultures grown on medium containing 1 mM AEC, They were able to grow stably with 2 mM AEC, while sensitive calli were inhibited by 0.5 mM AEC. Aspartate kinase activities of the resistant lines were insensitive to the natural inhibitor, Iysine, and accumulated 2.2 to 12.9-fold higher levels of free Iysine than that of the control cells. Especially, the levels of aspartate, asparagine, and methionine in the aspartate pathway showed higher accumulation in the AEC resistant lines than that in the control cells.

• Journal of KIEE
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• 제11권1호
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• pp.27-32
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• 2001

In this study, the luminance, luminous efficiency and address time of an PDP as a parameter of the phosphor thickness and the size of discharge space are investigated. The maximum luminance and luminous efficiency are obtained at the phosphor thickness of 30 ${\mu}{\textrm}{m}$ for the rib height of 110 ${\mu}{\textrm}{m}$. For the rib height of 120~160 ${\mu}{\textrm}{m}$, the maximum values are obtained at the thickness of 50 ${\mu}{\textrm}{m}$ regardless of the kind of R, G and B phosphor. These results do not affected by the variation of discharge space. The average decrease rate of the total charge to the phosphor thickness is about 3.35pc/cell/10 ${\mu}{\textrm}{m}$ and the average increase rate of the addressing time is about 0.027 $mutextrm{s}$/10 ${\mu}{\textrm}{m}$.

• 한국미생물·생명공학회지
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• 제21권1호
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• pp.54-58
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• 1993

미생물 대사산물로부터 phorbol ester에 의해 유도되는 K562 세포 표면의 소포형성 및 Protein kinase C(PKC)에 대한 저해제를 탐색하여 방선균 분리주 No.2007-18로 부터 용매추출 및 크로마토그래피의 기법을 이용하여 MT-2007을 분리하였다. MT-2007는 503.9MuM의 농도에서 phorbol 12,13-dibutylate에 의해 유도된 K562 세포표면의 bleb형성을 완전히 저해하였고, PKC 효소의 IC50 값은 31.4 MuM 이었다.

• 한국농림기상학회지
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• 제5권4호
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• pp.238-246
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• 2003

본 연구는 속리산 및 오대산 삼림식생을 기후환경요인 특히 고도 측면에서 밝혀 보고자 하였다. 속리산과 오대산 식생을 고도별로 볼 때 두 지역 간에 고도의 차이가 심하여 같은 고도에서 비교하기는 의미가 없겠으나, 속리산 조사구의 경우 500m 이하의 비교적 낮은 고도에서는 소나무, 굴참나무, 졸참나무, 벚나무 등이 중요치가 높게 출현함을 볼 수 있고, 800m이상의 높은 고도에는 신갈나무, 쇠물푸레, 당단풍 등이 중요치가 높게 출현된다. 오대산 조사구에서는 700 m 이하 조사구에서는 소나무, 개옻나무, 생강나무 등이 중요치가 높게 나타나고, 1000 m 이상 조사구에는 신갈나무, 당단풍, 피나무, 전나무, 까치박달, 거제수나무, 음나무, 참나무 등의 내한성이 강한 나무들이 중요치가 높게 출현한다. 이러한 결과들을 볼 때 신갈나무, 당단풍 피나무는 해발고가 높고, 유기물함량, 전질소, 양이온치환용량 등의 양료가 풍부한 곳에 분포하며 소나무, 굴참나무는 해발고가 낮고 유기물 함량, 전질소, 양이온치환용량 등의 양료가 적은 곳에 분포하고 있음을 알 수 있었다.

• 한국환경과학회지
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• 제33권8호
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• pp.591-604
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• 2024

To investigate the frequency and trajectories of volcanic ash from Mt. Baekdu reaching the Korean Peninsula, a forward trajectory analysis was conducted using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Through a cluster analysis of air parcel trajectories, we identified the main pathways of the volcanic ash from Mt. Baekdu entering the Korean Peninsula and analyzed the synoptic meteorological conditions on those days. The frequency of volcanic ash reaching the Korean Peninsula was 82 times at an altitude of 1000 m and 70 times at 2000 m, with an increasing trend from 2016 to 2022. This increase is attributed to the weakening of westerly winds and the strengthening of north-south winds due to global warming. Five and three trajectory clusters were classified at 1000 m and 2000 m, respectively. At a starting altitude of 1000 m, most air parcels originating from Mt. Baekdu entered the Korean Peninsula under weather conditions (C2, C3) where the pressure gradient from the northwest to the southeast was small, resulting in weak northerly winds. C2 and C3 showed shorter trajectories, which occurred in all seasons, except summer. At a starting altitude of 2000 m, air parcels mostly passed over the Korean Peninsula in a synoptic pattern similar to that at 1000 m in altitude; however, the air parcels had simpler paths and less frequent inflow. C2, at a starting altitude of 2000 m, originates from Mount Baekdu, crosses the center of the Korean Peninsula, and continues to the central region. At a starting altitude of 1000 m, volcanic ash can enter the Korean Peninsula when there is no strong low-pressure system to the southeast of the Korean Peninsula, whereas at 2000 m, volcanic ash can enter the Korean Peninsula when the Siberian high-pressure system is weak.

• Journal of applied mathematics & informatics
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• 제14권1_2호
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• pp.39-49
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• 2004

Let G be a simple graph and let $\={G}$ denotes its complement. We say that G is integral if its spectrum consists entirely of integers. If $\overline{aK_{a}\;{\bigcup}\;{\beta}K_{b}}$ is integral we show that it belongs to the class of integral graphs $[\frac{kt}{\tau}\;{x_0}\;+\;\frac{mt}{\tau}\;z}\;K_{(t+{\ell}n)+{\ell}m}\;\bigcup\;[\frac{kt}{\tau}\;{y_0}\;+\;\frac{(t\;+\;{\ell}n)k\;+\;{\ell}m}{\tau}\;z]n\;K_{em)$, where (i) t, k, $\ell$, m, $n\;\in\;\mathbb{N}$ such that (m, n) = 1, (n,t) = 1 and ($\ell,\;t$) = 1 ; (ii) $\tau\;=\;((t\;+\;{\ell}n)k\;+\;{\ell}m,\;mt)$ such that $\tau\;$\mid$kt$; (iii) ($x_0,\;y_0$) is a particular solution of the linear Diophantine equation $((t\;+\;{\ell}n)k\;+\;{\ell}m)x\;-\;(mt)y\;=\;\tau\;and\;(iv)\;z\;{\geq}\;{z_0}$ where $z_{0}$ is the least integer such that $(\frac{kt}{\tau}\;{x_0}\;+\;\frac{mt}{\tau}\;{z_0})\;\geq\;1\;and\;(\frac{kt}{\tau}\;{y_0}\;+\;\frac{(t+{\ell}n)k+{\ell}m}{\tau}\;{z_0})\;\geq\;1$.

• 아시안잔디학회지
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• 제11권4호
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• pp.303-309
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• 1997

The investigation was cycle of aluminum of surface soil elements in dynamic grassland ecosystems at a steady state in a Zoysia japonica and a Miscanthus sinensis ecosystem in Mt. Kwanak, Korea. Average amounts of total storage for aluminum in Z japonica and M. sinensis grasslands were 8,426mg /$m^2$ and 7,849mg /$m^2$ respectively. Decay constants estimated on the base of experimental and mathematical model, were 0.04 in Z japonica grassland, and 0.08 in M. sinensis grassland. Half time to decay aluminum of litter soils were 17.33 years in Z japonica grass-land, and 8.66 years in Al. sinensis grassland. 95% decay times in Z japonica, and in M. sinensis grassland were 75.0 years and 35.0 years respectively. Needed times to lose almost all of elements in Z japonica and M. sinensis grassland were 125.0 years, and 62.50 years respectively. The metals were losed more rapidly in M. sinensis than in Z japonica grassland. The cycle of aluminum was investigated to be related with soil acidity. Key words: Cycle of aluminum, Zoysia japonica. Miscanthus sinensis, Mt. Kwanak, Decay constants, Soil acidity.

• The Korean Journal of Ecology
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• 제14권4호
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• pp.435-448
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• 1991

Mt. paektu(altitude 2,749.6m) is ecologically important because successional processes following volcanic eurption are quite clear. We investigated plant communities with altitude know vertical distribution of plant vegetation on the north-western slope of Mt. paektu was divided into five parts; the pine-hardwood forest zone(600∼1,000m alt.), the lower coniferous forest zone (1,000∼1,500 m alt.), the upper coniferous forest and birch forest zone(1,500∼2,000 m alt.), the alpine shrub zone(2,000∼2,500 m alt.) and the alpine meadow zone(2,500∼2,749 m alt.). In particular, the alpine zone was divided into alpine shrub and alpine meadow zones and distributed up to 2,500m alt. these results reflet the adaptations of these shrubs at this altitude. But these shrubby communities disappeared on the alpinemeadow zone. In the alpine meadow zone above than 2,500m alt., some meadows, papaver radicatum var pscudoradicatum. bistorta ochotensis, chrysathemum zawadskii var. latilobum etc., were occured.