• Journal of Photoscience
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• 제9권2호
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• pp.70-73
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• 2002

A cyanobacteria-like organism Aaryochloris marina performs oxygenic photosynthesis with near far-red light by the use of chlorophyll d. Reaction center chlorophyll (Chl) of Photosystem (PS) II of A. marina was studied by analysis of millisecond-delayed fluorescence. Delayed fluorescence is emitted by Chi d indicating efficient energy transfer between antenna Chi d molecules and the unknown primary electron donor of PS II. P740 a reaction center Chl of PS I of A. marina is shown to give a dimer type cation, and triplet state with a D value of 245xlO$\^$-4/ cm$\^$-l/ in contrast to the 280-290 xlO$\^$-4/cm$\^$-l/ values of P700 suggesting triplet spins interacting at a 5% larger distance in P740 than in P700.

• Journal of Photoscience
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• 제9권2호
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• pp.367-369
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• 2002

Chlorophyll (ChI) a' is the Cl3$^2$-epimer of ChI a which is the constituent of P700, the primary electron donor of Photosystem (PS) I, of a thrmophilic cyanobacterium, Synechococcus elongatus, whose structure was recently determined by X-ray crystallography. To determine whether PS I of diverse oxygenic photosynthetic organisms universally contain one molecule of ChI a ’, pigment compositions of thylakoid membranes and PS I complexes isolated from cyanobacteria, green algae, red algae and higher plants were determined by reversed-phase HPLC. The results show that involvement of one ChI a'molecule in PS I is the universal feature for Chi a-based PS I of oxygenic photosynthetic organisms.

• 한국환경과학회지
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• 제26권5호
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• pp.601-608
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• 2017

The effects of elevated atmospheric $CO_2$ on growth and photosynthesis of soybean (Glycine max Merr.) were investigated to predict its productivity under elevated $CO_2$ levels in the future. Soybean grown for 6 weeks showed significant increase in vegetative growth, based on plant height, leaf characteristics (area, length, and width), and the SPAD-502 chlorophyll meter value (SPAD value) under elevated $CO_2$ conditions ($800{\mu}mol/mol$) compared to ambient $CO_2$ conditions ($400{\mu}mol/mol$). Under elevated $CO_2$ conditions, the photosynthetic rate (A) increased although photosystem II (PS II) photochemical activity ($F_v/F_m$) decreased. The maximum photosynthetic rate ($A_{max}$) was higher under elevated $CO_2$ conditions than under ambient $CO_2$ conditions, whereas the maximum electron transport rate ($J_{max}$) was lower under elevated $CO_2$ conditions compared to ambient $CO_2$ conditions. The optimal temperature for photosynthesis shifted significantly by approximately $3^{\circ}C$ under the elevated $CO_2$ conditions. With the increase in temperature, the photosynthetic rate increased below the optimal temperature (approximately $30^{\circ}C$) and decreased above the optimal temperature, whereas the dark respiration rate ($R_d$) increased continuously regardless of the optimal temperature. The difference in photosynthetic rate between ambient and elevated $CO_2$ conditions was greatest near the optimal temperature. These results indicate that future increases in $CO_2$ will increase productivity by increasing the photosynthetic rate, although it may cause damage to the PS II reaction center as suggested by decreases in $F_v/F_m$, in soybean.

• 한국식물학회:학술대회논문집
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• 한국식물학회 2001년도 춘계학술발표대회:발표눈문요지록
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• pp.22-22
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• 2001

• BMB Reports
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• 제40권5호
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• pp.644-648
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• 2007

Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 ${\mu}mol$ photons $m^{-2}s^{-1}$) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 ${\mu}mol$ photons $m^{-2}s^{-1}$) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 ${\mu}mol$ photons $m^{-2}s^{-1}$ caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.

• 아시안잔디학회지
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• 제11권1호
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• pp.45-58
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• 1997

Pigments and thylakoid membrane proteins were investigated in wild type and PS I- mutants from Synechocystis sp. PCC6803 Comparing morphological features, B2 was less fluorescent than the other strains. The contents of chlorophyll a were propotional to the FNR activity in thylakoid membrane. The FNR activity of mutants was lower than that of wild type. In the result of pigments analysis, mutants had smaller cholophyll a than that of wild type. The major carotenoid was found to he $\beta$-caroene, but aeaxanthin was barely detected in thylakoid membrane of mutants. The polypeptide, 14.8kD was detected by electrophoresis in mutants. It was considered to be the modification of 15.4kD in wild type. Membrane polypeptides of 17.6 and 19.7kD were not detected in mutants. In the result of western blotting, subunit I was detected in all strains, but subunit II was barely detected in mutants. Subunit II was not detected in B2 at all. In view of the results so far achieved, the changes of contents of chlorophyll and zeaxanthin were affected by the defficiency or modification of functional domain in subunit I. Also the modification in subunit I affected the subunit II- binding site in PS I. As the result, efficiency of photosynthesis was decreased. Key words: Synechoystis sp. PCC6803, PS I - mutant, Photosynthetic efficiency, Pigment,Thylakoid membrane proteins, Subunit I, II.

• Journal of Ginseng Research
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• 제12권1호
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• pp.11-29
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• 1988

온도 및 광도가 인삼의 광합성 및 호흡에 미친 영향을 검토하였던 바 그 결과를 요약하면 다음과 같다. 1. 온도 및 광도와 인삼잎의 광합성간에는 고도로 유의한 2차곡선회귀가 인정되었으며 광합성에 대한 온도와 광도의 효과간에는 고도로 유의한 교호작용이 인정되었다. 2. 광도의 상승에 따르는 광합성 증가율은 온도가 높아질수록 현저한 감소를 보였고 광보상점은 온도에 따라 현저한 차이를 보였으며 각 온도의 평균 광보상점은 약 600lux였다. 그리고 고려인삼의 경우 최대광합성온도는 $15^{\circ}C$ 및 $20^{\circ}C$에서는 11,000lux였고 $25^{\circ}C$ 이상에서는 9,500lux내외였다. 3. 온도의 상승에 따르는 광합성의 감소율은 광도를 높일수록 현저히 크게 나타났으며 광합성 최적온도는 15~$22^{\circ}C$로서 광도를 높일수록 최적온도는 현저히 낮아지는 경향을 보였다. 4. 투광율 15% 일복하에서 생육한 잎의 광합성량이 가장 높았고 5% 투광율에 비해 30% 투광율에서 생육된 잎의 호흡량이 현저히 많았으며 또한 온도가 높을수록 호흡량은 현저히 증가되었다. 5. 호흡율은 고온에서 높았고 광도가 높을수록 낮아졌으며 일복하의 투광율이 높아질수록 현저히 증가되었다. 6. 일중 최대 $CO_2$ 흡수는 5% 및 15% 투광일복하에서 오전 9시 그리고 20% 투광일복하에서는 오전 7~9시경에 일어났으며 투광율이 높은 일복하에서 $CO_2$ 흡입 기간은 현저히 길었다. 7. 인삼잎의 광합성에 있어서 $CO_2$ 보상점은 130ppm이었다.

• Journal of Plant Biology
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• 제31권4호
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• pp.299-307
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• 1988

The electron transport activities of choloroplasts isolated from hte detached rise (Oryza sativa L. cv. Chucheong) leave stored under low temperature(4$^{\circ}C$) with light illumination were investigated to understand the role of light in the low temperature inhibition of photosynthesis in the chilling-sensitive plants. Chlorophyll content of the detached leaves upon incubation at 28$^{\circ}C$ and 4$^{\circ}C$ in the dark was also measured. The rice seedlings were grown with Hoagland medium in the growth chamber of 28$^{\circ}C$ temperature and 400 ft.c fluorescent light with the photoperiod of 16 h. Although chlorophyll content of the detached leaves stored in the dark declined by 61.7% after 28$^{\circ}C$ treatement, there occurred only 5.2% decrease of chlorophyll with 4$^{\circ}C$ treatment. Low temperature treatment(4$^{\circ}C$) for 6 days brought about decreases in total photosystem(PS II＋PS I) activities by 35.2% and 73.6% in te presence and absence of light, respectively, while after 28$^{\circ}C$ treatment of the detached leaves for 6 days in the dark there was only 27.6% decrease in PS II＋PS I activity. PS II activities were also decreased by 35.6% and 72.2% in the light and dark, respectively. PS I activities were decreased slightly, however, by 7.6% and 16.2% in the light and dark, respectively. Investigations into DPClongrightarrowDCPIP and NH2OHlongrightarrowDCPIP activities revealed that low temperature inhibition of PS II activities was not due to the inactivation of the water oxidation capacity at low temperature. It was concluded that light protects the electron transport activities of isolated rice chloroplasts from the inhibitory effect of low temperature in the detached leaves.

• Journal of Photoscience
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• 제8권1호
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• pp.13-17
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• 2001

Cucumber leaves subjected to light chilling stress exhibit a preferential inactivation of photosystem(PS) I relative to PSII, resulting in the photoinhibition of photosynthesis. In light chilled cucumber leaves, Cu/Zn-Superoxide dismutase(SOD) is regarded as a primary target of the light chilling stress and its inactivation is closely related to the increased production of reactive oxygen species. In the present study, we further explored that inactivation of PSI in cucumber leaves is not a light chilling specific, but general to various oxidative stresses. Oxidative stress in cucumber leaves was induced by treatment of methylviologen(MV), a producer of reactive oxygen species in chloroplasts. MV treatment decreased the maximal photosynthetic O$_2$ evolution, resulting in the photoinhibition of photosynthesis. The photoinhibition of photosynthesis was attributable to the decline in PSI functionality determined in vivo by monitoring absorption changes around 820 nm. In addition, MV treatment inactivated both antioxidant enzymes Cu-Zn-superoxide dismutase and ascorbate peroxidase known sensitive to reactive oxygen species. From these results, we suggest that chloroplast antioxidant enzymes are the primary targets of photooxidative stress, followed by subsequent inactivation of PSI.

• 한국약용작물학회지
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• 제16권6호
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• pp.416-420
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• 2008

This study was conducted to investigate the influence of shading material on the chlorophyll fluorescence, photosynthesis, transpiration, stomatal conductance and its any correlations in Panax ginseng C.A.Meyer. Fo was higher in polyethylene shade net than in silver-coated shading plate, but this treatment caused a lower Fm in comparison with silver-coated shading plate. Also, Fv/Fm and PhiPS2 showed higher in silver-coated shading plate than in polyethylene shade net. The relationship between net photosynthetic rate and transpiration, stomatal conductance were increased as the PAR (Photosynthetic active radiation) was increased and reached maximum at the $200-400\;{\mu}mol/m^{2}/s$ of PAR in all of leaves, and the higher in silver-coated shading plate than in polyethylene shade net. A linear equation was obtained between net photosynthetic rate and transpiration, net photosynthetic rate and stomatal conductance. SPAD was higher in silver-coated shading plate than in polyethylene shade net.