• Journal of Plant Biology
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• 제36권2호
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• pp.133-140
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• 1993

The photosynthetic activities in relation to oxygen evolution rates, quantum yield, CO2 uptake rates and room temperature chlorophyll fluorescence were investigated in cotyledons of cucumber seedlings exposed to low temperature (at 4$^{\circ}C$) for 24 h. Light-chilling caused more inhibition on light-saturated maximum oxygen evolution rates, quantum yield, and CO2 uptake rates than dark-chilling did in the cucumber plant. Light-chilling induced more marked increase in Fo and decrease in (Fv)m/Fm than dark-chilling did in the room temperature chlorophyll induction kinetics. The above results affected by chilling in the light are considered to be associated with the partial damage of the reaction center of PS II and the decreased photosynthetic activities. There occurred a large decrease in qQ with little change in qNP in the light-chilling plant. When light- and dark-chilled plants were recovered at room temperature for 24 h and their chlorophyll fluorescences were induced with light doubling technique, light-chilled plants showed more smaller magnitude and rate of fluorescence relaxation than dark-chilled plants. These suggest that light-chilling might cause some alterations in transthylakoid pH formation, and that photosynthetic apparatus of cucumber cotyledons is more susceptible to light-chilling. In the fast fluorescence induction kinetics, FR was decreased by 60% in the light-chilled plants with reference to $25^{\circ}C$ light-grown plants, while the dark-chilled plants showed a decreased rate of only 20% with reference to $25^{\circ}C$ dark-treated plants for 24 h, indicating that cucumber seedling is very sensitive to chilling stress. So, it is certain that chilling injury to the photosynthetic apparatus is strongly dependent on the presence of light in cucumber seedlings.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권3호
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• pp.177-188
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• 1999

The effect of ABA on the chloroplast disassembly of Zea mays was investigated by measuring the changes in the relative distribution of chlorophyll(Chl) between the Chl-protein complexes in ABA treated and untreated sensecting leaves. The reaction center(RC)-light harvesting complex(LHC) regions were rapidly disassembled in the late stage of dark-induced senescence. Plus, during dark-induced senescence, the disassembly of a reaction center of P700 apoproteins containing mainly Chl a was faster than that of a reaction center of LHCI apoproteins containing both Chl a and Chl b. The increase in the relative distribution of Chl-protein complexes in the RC-Core2 in the late stage of senescence was due to the accumulation of core complexes such as CP47/43 and reaction centers including D1/D2 apoproteins disassembled from the RC-Corel containing the dimer of D1/D2 apoproteins. The LHCII region was more stable than the other Chl-protein complexes throughout leaf senscence. Accordingly, it is suggested that the preferential breakdown of Chl a gives rise to the disassembly of Chl a-binding proteins, particularly reaction centers and core complexes during dark-induced senescence, plus the primary target of the photosynthetic apparatus in sensecing leaves would seem to be Chl a along with the proteins associated with Chl a. The application of ABA promoted the disassembly of the P700 apoproteins in the PSI reaction center and the dimer of D1/D2 apoproteins, and the conversion of the trimeric LHCII apoprotein to the monometirc LHCII apoprotein during the middle stage of leaf senescence, thereby suggesting that ABA accelerates the disassembly of both Chl a-binding and Chl a+b-binding proteins, particularly Chl a-binding proteins during the middle stage of leaf senescence.

• KSBB Journal
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• 제20권6호
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• pp.393-400
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• 2005

수소를 생산하는 미생물은 크게 광합성 세균(photosynthetic bacteria), 혐기성세균(non-photosynthetic anaerobic bacteria), 조류(algae) 등으로 구분되고, 이들의 수소 생성 기작, 사용가능기질 및 수소 발생량은 상당한 차이가 있다. 광합성세균은 Rhodospirillaceae, Chromatiaceae 및 Chlorobiaceae로 구분되며, 이는 각각 홍색비유황세균(purple non-sulfur bacteria), 홍색유황세균(purple sulfur bacteria), 녹색유황세균(green sulfur bacteria)으로 통칭된다. 혐기성 세균은 절대 또는 통성혐기세균중 일부가 수소생산에 관여하며, 조류는 녹조류(green algae)와 남조류(blue-green algae, cyanobacteria)가 알려져 있다. 생물학적 수소생산 기술은 (1) 녹조류(green algae)가 광합성 메카니즘에 의해 수소를 생산하는 직접 물 분해 수소생산(direct bio-photolysis) (2) 광합성 작용에 의해 물을 분해하여 산소를 발생하고, 동시에 공기 중 이산화탄소를 고정하여 고분자 저장물질로 균체 내에 저장한 후 혐기 발효 또는 광합성 발효에 의해 수소를 발생하는 간접 물 분해 수소생산(indirect bio-photolysis or two stage photolysis) (3) 빛이 존재하는 혐기상태 배양 조건에서 홍색 세균에 의한 광합성 발효(photo-fermentation) 또는 (4) 광이 존재하지 않는 조건에서 혐기 미생물에 의해 수소와 유기산을 내는 혐기 발효(dark anaerobic fermentation) (5) 균체 외(in virro) 수소 발생 (6) 일산화탄소 가스 전환 반응(microbial gas shift reaction)에 의한 수소 생산 기술로 구분할 수 있다. 물로부터 생물학적 기술에 의한 수소생산은 공기 중의 이산화탄소를 고정하고, 수소와 산소를 발생하는 원천기술로써 오래 전부터 미국, 유럽에서 태양에너지를 이용하는 광합성 미생물의 분리, 개선 및 반응기에 관한 연구가 축적되어 왔으며, 유기물 즉 바이오매스로부터 혐기 및 광합성 발효를 연속적으로 적용하는 기술은 비교적 최근에 일본을 비롯한 유기성 폐기물이 많은 국가에서 수소에너지 생산과 유기성 폐기물 처리라는 두 가지 목적에 부합하는 연구로써 활발히 진행되고 있다. 유기성 폐기물이나 폐수와 같은 수분함량이 높은 바이오매스는 대부분이 매립처리 되는 실정이지만 높은 수분 함량 때문에 매립 시 발생하는 침출수는 환경오염의 주범으로 가까운 장래에는 매립도 금지될 전망이다. 이와 같은 수소에너지 생산기술과 이용시스템 개발은 화석연료 사용을 최소화 할 수 있으며, 국내에서 다량 발생하는 유기성 폐기물을 이용한 에너지 생산으로 자원 강대국 입지에 설 수 있다. 미생물에 의한 수소생산 기술은 청정에너지 생산과 아울러, 동시에 산소 발생, 공기 중 이산화탄소 고정, 식품공장 폐수 및 음식쓰레기와 같은 유기성 폐기물 처리 등 환경에 이로운 방향으로 진행될 뿐만 아니라, 미생물 자체가 갖는 생물 산업성도 높아서 비타민류, 천연색소, 피부암 치료제등의 고부가가치 의약품 생산도 활성화할 수 있다.

• 한국농림기상학회지
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• 제8권2호
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• pp.54-60
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• 2006

내음성이 강한 죽절초 유묘를 대상으로 죽절초의 생육환경 변화에 따른 반응을 보기 위하여 서로 다른 광조건의 비음처리 I, II, III 그리고 자연조건(full sunlight)을 구분하여 각 처리구별 죽절초의 생리적 반응을 비교하였다. 생리적 반응의 비교를 위한 측정요소로 엽록소 함량, 광합성율, 기공전도도, 엽육 세포내 $CO_2$농도를 조사하였다. 비음처리구간간의 차이는 크게 나타나지 않았으나, 자연조건과 비음 처리구와의 차이는 크게 나타났다. 자연조건(full sunlight)일 때, 죽절초는 비음 처리구에 비하여 낮은 엽록소 함량과 광합성율, 기공전도도를 나타냈으며, 엽육 세포내 $CO_2$농도와 수분이용효율이 높게 나타났다. 이것은 죽절초의 광합성기구에 광저해 현상이 일어나 광반응 기구에 피해를 준것으로 보여지며, 적은 양의 빛을 효율적으로 이용하기 위해 순화된 죽절초는 높은 광조건하에서 잘 적응하지 못하고, 높은 광이 스트레스로 작용함을 알 수 있다.

• Journal of Photoscience
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• 제9권2호
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• pp.373-375
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• 2002

Lhcb genes encoding light-harvesting chlorophyll-a/b binding (LHC) proteins of photosystem (PS) II were comprehensively characterized using the expressed sequence tag (EST) databases in the green alga, Chlamydomonas reinhardtii. The gene family was composed of eight Lhcb genes including four new genes, which were isolated and sequenced. The effects of light intensity on the levels of mRNAs accumulation of multiple Lhcb genes were studied under various conditions. The results indicate that Lhcb genes are coordinately regulated in response to light conditions, and repressed when the input light energy exceeded the requirement for $CO_2$ assimilation. The effects of high light on the expression of the Lhcb genes observed in the presence of an electron transport inhibitor, DCMU, and in mutants deficient in photosynthetic reaction centers suggest the presence of two alternative mechanisms for regulating the genes expression under high-light conditions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.272-272
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• 2013

The attractive features of photosynthetic reaction center proteins for energy application make them useful in solar energy conversion to hydrogen fuel or electrical energy. Almost unity charge separation quantum yield and its rapid speed of ~1ns, absorbance region in visible light (480~740 nm) and high proportion of photosynthetically active solar energy of 48.5% allowed photosystem1 to exploited as a bio-material for photo-energy devices. Directionality of photosystem1 in electron transfer can solve main problem in two-step water splitting process where back reaction deteriorates the overall efficiency. In the study, photosystem1 was extracted from spinach and the photo-induced excited electron in the reaction center was utilized in various field of light energy application. First, hydrogen evolving system realized by photodeposition of platinum at the end of the electron transfer chain, with combining specific semiconductor to oxidize water in the first step of Z-scheme. The evaluation by gas-chromatography demonstrated hydrogen evolution through the system. For the further application of photoelectrical material on electrode, photosystem1 have been controlled by copper ion, which is expected to assemble photosystem in specific orientation followed by maximized photoelectrical ability of film. The research proposed concrete methods for combining natural protein and artificial materials in one system and suggested possibility of designing interface between biological and inorganic materials.

• Journal of Photoscience
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• 제3권1호
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• pp.15-21
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• 1996

To investigate the chilling sensitivity related injuries in the photosynthetic apparatus of cucumber leaves, the light-chilling induced alterations of chlorophyll fluorescence transients in cucumber leaves were compared with those in pea leaves. As an early effect of light-chilling, an increase in Fp/Fm$^*$ was observed in both pea and cucumber leaves, which was saturated by about 6 h chilling. However, the saturated value of Fp/Fm was almost 1.0 in cucumber, in contrast to about 0.8 in pea. During the recovery period after 24 h chilling, the light-chilling induced changes in pea seemed to be reversed, but those in cucumber leaves were thought to be irreversible, because Fo was increased significantly. Light-chilling caused significant decreases in qQ and qE in cucumber leaves, but qR was increased until 6 h, and decreased thereafter. In both pea and cucumber leaves, Fm was increased by 2 h dark treatment. The Fm from the predarkened pea leaf discs was higher than the value from the preilluminated ones during the whole period of light-chilling (500 $\mu$mol m$^{-2}$s$^{-1}$ PAR). However, the predarkened cucumber leaf discs showed a reduction in Fm and an increase in Fo during the 2 h chilling in the light. These results indicate that the causes of chilling sensitivities in photosynthetic apparatus of cucumber leaves are possibly related with the damage in PSI reaction center and the ability of acidification of lumen by PSII.

• 한국약용작물학회지
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• 제22권1호
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• pp.38-45
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• 2014

This study was performed to investigate the physiological responses of Oplopanax elatus by water condition. Drought stress was induced by withholding water for 26 days. The results show that $P_{N\;max}$, SPAD, gs, E and Ci were significantly decreased with decreasing of soil moisture contents. However, AQY and WUE were decreased slightly only at 26 day. This implies that photosynthetic rate is reduced due to an inability to regulate water and $CO_2$ exchange through the stomatal. According to JIP analysis, ${\Phi}_{PO}$, ${\Psi}_O$, ${\Phi}_{EO}$ and $PI_{ABS}$ were dramatically decreased at 21 day and 26 day, which reflects the relative reduction state of the photosystem II. On the other hand, the relative activities per reaction center such as ABS/RC, TRo/RC were significantly increased at 26 day. Particularly, Dio/RC and DIo/CS increased substantially under drought stress, indicating that excessive energy was consumed by heat dissipation. These results of chlorophyll a fluorescence show that the sensitivity changes photosystem II activity. Thus, according to the results, O. elatus was exhibited a strong reduction of photosynthetic activity to approximately 10% soil moisture contents, and JIP parameters could be useful indicator to monitor the physiological states of O. elatus under drought stress.

• Journal of Plant Biotechnology
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• 제1권1호
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• pp.61-68
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• 1999

Rapid accumulation of reactive oxygen species (ROS) and their toxic reaction products with lipids and proteins significantly contributes to the damage of crop plants under biotic and abiotic stresses. We have identified several stress activated alfalfa genes, including the gene of the alfalfa ferritin and a novel NADPH-dependent aldose/aldehyde reductase enzyme. Transgenic tobacco plants that synthesize alfalfa ferritin in vegetative tissues-either in its processed form in chloroplast or in the cytoplasmic non-processed form-retained photosynthetic function upon free radical toxicity generated by paraquat treatment and exhibited tolerance to necrotic damage caused by viral and fungal infections. We propose that by sequestering intracellular iron involved in generation of the very reactive hydroxyl radicals through a Fenton reaction, ferritin protects plant cells from oxidative damage. Our preliminary results with the other stress-inducable alfalfa gene (a NADPH-dependent aldo-keto reductase) indicate, that the encoded enzyme may play role in the stress response of the plant cells. These studies reveal new pathways in plants that can contribute to the increased stress resistance with a potential use in crop improvement.

• The Korean Journal of Ecology
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• 제24권2호
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• pp.93-100
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• 2001

One-year-old cottonwood (Populus deltoides Bartr.) clones, which were classified as sensitive or tolerant, were exposed to 150 n1/1 ozone (O$_3$) over 8 days for 8 hours each day under glass chamber conditions with natural sunlight. The leaves of the sensitive clone had black stipple and bifacial necrosis after $O_3$ treatment. Photosynthesis and stomatal conductance were measured before, during, and after the $O_3$ treatment. The photosynthetic rates due to $O_3$ treatment were decreased 51 percent and 34 percent on the sensitive and tolerant clone, respectively. The stomatal conductance of the sensitive clone was more than 40 percent higher than that of the tolerant clone regardless of the $O_3$ treatment. As light intensity increased, the $O_3$ effect on photosynthesis was clear. Compared to the previous growth chamber studies, our natural light exposure system was able to maintain a stable photosynthetic responses of the control treatment throughout the fumigation period. In addition, changes in assimilation versus intercellular $CO_2$ concentration (A/C curves) showed that $O_3$ decreased the slope and asymptote of the curves for the sensitive clone. This indicates that $O_3$ decreases the biochemical capacity of photosynthesis on the sensitive clone. Chlorophyll contents and fluorescence of the two clones were analyzed to examine the $O_3$ effects on photosystem 11, but $O_3$ did not impact these variables on either clone. Although the tolerant clone did not show any foliar injury, we could not find any ecophysiological defensive responses to $O_3$ treated. Stomatal conductance of the tolerant clone was originally much lower than that of the sensitive one. Thus, the mechanisms of the tolerant clone in this system are to narrowly open stomata and efficiently maintain photosynthesis with a more durable biochemical apparatus of photosynthesis under $O_3$ stress. The sensitive clone has higher photosynthetic capacity and more efficient light reaction activity than the tolerant one under charcoal filtered condition, but is not as resilient under stress.