• 한국환경과학회지
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• 제21권12호
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• pp.1435-1447
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• 2012

The present study was conducted to determine the effect of hexaconazole (HEX), a triazole fungicide, on the growth, yield, photosynthetic response and antioxidant potential in cucumber (Cucumis sativus L.) plants subjected to UV-B stress. UV-B radiation and HEX were applied separately or in combination to cucumber seedlings. The growth parameters were significantly reduced under UV-B treatment, however, this growth inhibition was less in HEX treated plants. HEX caused noticeable changes in plant morphology such as reduced shoot length and leaf area, and increased leaf thickness. HEX was quite persistent in inhibiting shoot growth by causing a reduction in shoot fresh and dry weight. HEX noticeably recovered the UV-B induced inhibition of biomass production. Significant accumutation in anthocyanin and flavonoid pigments in the leaves occurred as a result of HEX or UV-B treatments. HEX permitted the survival of more green leaf tissue preventing chlorophyll content reduction and higher quantum yield for photosystemII under UV-B exposure. HEX treatment induced a transient rise in ABA levels in the leaves, and combined application of HEX and UV-B showed a significant enhancement of ABA content which activates $H_2O_2$ generation. UV-B exposure induced accumulation of $H_2O_2$ in the leaves, while HEX prevented UV-B induced increase in $H_2O_2$, indicating that HEX serves as an antioxidant agent able to scavenge $H_2O$ to protect cells from oxidative damage. An increase in the ascorbic acid was observed in the HEX treated cucumber leaves affecting many enzyme activities by removing $H_2O_2$ during photosynthetic processes. The activities of antioxidant enzymes including catalase(CAT), ascorbate peroxidase(APX), superoxide dismutase(SOD) and peroxidase(POD) in the leaves in the presence of HEX under UV-B stress were higher than those under UV-B stress alone. These findings suggest that HEX may participate in the enhanced tolerance to oxidative stress. From these results it can be concluded that HEX moderately ameliolate the effect of UV-B stress in cucumber by improving the components of antioxidant defense system.

• 한국농림기상학회지
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• 제7권3호
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• pp.220-226
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• 2005

오존 노출이 버즘나무의 광합성 특성에 미치는 영향을 조사하기 위하여, 2년생 버즘나무 유묘에 하루에 8시간씩 100 ppb의 오존을 처리하였다. 오존 처리를 진행하는 동안, 3주마다 버즘나무의 엽내 엽록소 함량과 광합성 특성을 측정하였다. 오존에 의한 잎의 가시적 피해는 나타나지 않았으며, 또한 엽내 엽록소 함량은 대조구와 뚜렷한 차이를 보이지 않았다. 그러나 광합성량, 기공전도도, 수분이용효율은 오존 처리 6주 후에 대조구보다 감소하였다. 한편 탄소고정효율과 광화학 효율은 오존 처리 3주와 6주 후에서 감소한 것으로 나타났다. 위의 결과를 토대로 볼 때, 탄소고정효율은 오존 스트레스에 가장 민감한 파라미터로 나타났으며, 이것은 오존 민감성을 평가하기 위한 매우 적당한 지표로 생각되었다.

• 환경생물
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• 제17권1호
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• pp.1-9
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• 1999

산업활동의 부산물인 chlorofluorocarbons(CFCs)와 같은 물질들의 대기권 유입으로 오존층의 파괴가 극심해짐에 따라 자외선의 지표유입량이 증가되는 추세를 보이는데, 특히 중파자외선의 증가는 DNA, 단백질, 지질 등에 의한 흡수를 통하여 생물학적 폐해를 야기할 수 있다는 점에서 주목된다. 최근 측정 결과 우리나라 동해안에서 해수표면에 도달되는 중파자외선 광량의 1%가 수심 l0 m까지 침투하는 것으로 나타났는데, 이는 해양생태계 생산성의 대부분이 해양 수심의 상위 2.5%에 해당되는 투광대에 의존한다는 점을 감안할 때 자외선에 의한 막대한 생태학적 폐해를 예견하게 해준다. 실내배양실험 연구에서 중파자외선은 대형해조류의 생장 및 광합성을 억제하고 광합성 색소를 파괴하는 등의 생물독성학적 효과를 보였다. 반면, 자외선의 피해로부터 해조류를 보호해 주는 몇 가지 기작이 밝혀진 바 있는데, 어린시기의 갈조류 다시마는 청색광에 의한 광재활성화 능력을 함유한 것으로 보이고, 한국산 녹조 구멍갈파래와 홍조 도박류에서는 자외선을 강하게 차단하는 흡수물질이 형성됨을 알 수 있었다. 그러나 이러한 적응기능들이 해조류에서 보편적으로 나타나는 것인지에 대해서는 좀 더 연구가 필요하다. 해양생태계는 대기 중 CO$x_2$를 이용하여 1년에 약 100 Gt의 유기물질을 생산해내고, 인류가 소비하는 식품의 30%를 제공한다는 점에서 자외선에 의한 생물량의 감소는 해조류 뿐만 아니라 먹이망에 의해서 복잡한 연결구조를 지닌 생태계 전체의 붕괴를 야기할 수 있는 심각한 사안이라고 할 수 있다. 따라서, 자외선에 대한 피해를 연구 평가하여 전략을 세우고 이를 예측하는 예보시스템을 개발할 필요성이 절실히 부각된다.

• 환경생물
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• 제26권1호
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• pp.15-21
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• 2008

Ionizing radiation causes many alterations in photosynthetic machineries. However, there is no information about effects of ionizing radiation on the development of photosynthetic machineries in plants. We investigated the greening of etiolated mung bean seedlings after gamma-irradiation of 50 to 300 Gy. The irradiation inhibited seedling growth with great dependence on the radiation dose. In particular, growth of stems was more affected than that of hypocotyls. Irradiated leaves showed inhibition in growth, aberration in morphology, and yellowing in color depending on the radiation dose. Contents of photosynthetic pigments such as chlorophylls and carotenoids were significantly decreased in the irradiated leaves. The apparent electron transport rate for photosynthesis, ETR, was similarly changed depending on the radiation dose. However, the maximal photochemical efficiency of Photosystem II (PSII), Fv/Fm, was little affected by the irradiation. Moreover, the 50-Gy seedlings maintained the control level of light saturating for photosynthesis and showed slightly higher Fv/Fm values in spite of significant decreases in the photosynthetic pigment content and ETR. These results suggest that the inhibition of the overall photosynthetic capacity couldn’t be causally relatqaed with the repression in the initial development of irradiated seedlings and that the overall photosynthetic machineries can develop and work to some extent as a concerted system for photosynthesis even after exposure to acute doses of ionizing radiation.

• ALGAE
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• 제38권2호
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• pp.141-150
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• 2023

Light quality is a common environmental factor which influences the metabolism of biochemical substances in algae and leads to the response of algal growth and development. Pyropia yezoensis is a kind of economic macroalgae that naturally grows in the intertidal zone where the light environment changes dramatically. In the present study, P. yezoensis thalli were treated under white light (control) and monochromatic lights with primary colors (blue, green, and red) for 14 days to explore their physiological response to light quality. During the first 3 days of treatment, P. yezoensis grew faster under blue light than other light qualities. In the next 11 days, it showed better adaptation to green light, with higher growth rate and photosynthetic capacity (reflected by a higher rETR_max = 61.58 and E_k = 237.78). A higher non-photochemical quenching was observed in the treatment of red light than others for 14 days. Furthermore, the response of P. yezoensis to light quality also results in the difference of photosynthetic pigment contents. The monochromatic light could reduce the synthesis of all pigments, but the reduction degree was different, which may relate to the spectral absorption characteristics of pigments. It was speculated that P. yezoensis adapted to a specific or changing light environments by regulating the synthesis of pigments to achieve the best use of light energy in photosynthesis and premium growth and metabolism.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2005년도 International Meeting of the Microbiological Society of Korea
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• pp.64-66
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• 2005

Photosynthetic microbes possess a wealth of photoactive proteins including chlorophyll-based pigments, phototropin-related blue light receptors, phytochromes, and cryptochromes. Surprisingly, recent genome sequencing projects discovered additional photoactive proteins, retinal-based rhodopsins, in cyanobacterial and algal genera. Most of these newly found rhodopsin genes and retinal synthase have not been expressed and their functions are unknown. Analysis of the Anabaena and Chlamyrhodopsin with retinal synthase revealed that they have sensory functions, which, based on our work with haloarchaeal rhodopsins, may use a variety of signaling mechanisms. Anabaena rhodopsin is believed to be sensory, shown to interact with a soluble transducer and the putative function is either chromatic adaptation or circadian rhythm. Chlamydomonas rhodopsins are involved in phototaxis and photophobic responses based on electrical measurements by RNAi experiment. In order to analyze the protein, we developed a sensory rhodopsin expression system in E. coli. The opsin in E. coil bound endogenous all-trans retinal to form a pigment and can be observed on the plate. Using this system we could identify retinal synthase in Anabaena PCC 7120. We conclude that Anabaena D475 dioxygenase functions as a retinal synthase to the Anabaena rhodopsin in the cell.

• 한국균학회지
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• 제18권4호
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• pp.181-190
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• 1990

The growth and biochemical activities of Chlorella fusca were studied in the presence of different concentrations of either filtrates or mycelial mats of Saprolegnia ferax and Pythium graminicola. Low concentrations of both fungal filtrates exerted increase in total count, dry weight and in the biosynthesis of photosynthetic pigments, carbohydrates and nitrogen content. High concentrations showed inhibitory effect on both growth and biochemical activities of Chlorella fusca. Supplementation with different concentrations of dry mycelial mats of either fungi the culture of Chlorella showed elevation in biomass, dry weight, and biosynthesis of carbohydrates and nitrogen content especially at low concentrations. The contents of photosynthetic pigment were inhibited only at low concentrations. Neither the culture filtrate of Pythium nor Saprolegnia had cellulolytic activity, although polygalacturonase enzymes were detected, whereas chloroform-extract of both fungal filtrates showed blue spots under long wave light (366 nm).

• ALGAE
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• 제20권4호
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• pp.369-377
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• 2005

Seashore joining with land and sea, which is typical habitat for marine macroalgae, is classified two types of shore as soft- and hard-bottom shore according to topographical (geological) and ecological features. We compared two of Ulva pertusa Kjellman from two contrasting habitats, sandy (soft-bottom, Haenam) and rocky shore (hard-bottom, Hadong) in terms of chlorophyll-a fluorescence and its parameters, and various photosynthetic pigment and nutrient content in the tissue of those. Both of habitats were different in the light environment such as light attenuation coefficient and even in nutrient concentration of ambient seawater. Electron transport rate (ETR) of Ulva from sandy shore was higher than from rocky shore. The range of photosynthetic pigment content in the tissue of U. pertusa was significantly much more in from sandy shore, and also nitrogen and phosphorus content were significantly higher except for carbon content. However, there were no significant differences in the ratio of among photosynthetic pigments, and N:P ratio was similar between each other, even though significantly different. Our result implied on the reason of why most of green tides in the worldwide concentrated and frequently occurred at sites with sandy, muddy and silty bottoms, being classified as soft-bottom shore.

• 한국해양학회지:바다
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• 제14권1호
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• pp.48-55
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• 2009

광양만 조간대 갯벌에 서식하는 저서미세조류와 해수 중 식물플랑크톤의 생체량과 군집조성의 계절변동 양상을 밝히기 위하여, 2002년 1월부터 11월까지 매월 high-performance liquid chromatograph(HPLC)를 이용한 광합성색소(photosynthetic pigments) 분석을 실시하였다. 광합성색소 분석결과 규조류(diatoms)의 주요 지표색소인 fucoxanthin, diadinoxanthin 그리고 diatoxanthin이 퇴적물과 상부 해수에서 연중 우점하여 나타났다. 이들을 제외한 다른 색소들은 상대적으로 낮은 농도를 보였다. 깊이 0.5 cm까지의 표층퇴적물에서 측정한 chlorophyll ${\alpha}$ 농도는 3.44${\sim}$169 mg $m^{-2}$의 범위로 연평균 농도는 상부, 중부 그리고 하부 갯벌 퇴적물에서 각각 $68.4{\pm}45.5,\;21.3{\pm}14.3,\;22.9{\pm}15.6mg\;m^{-2}$로 나타났다. 반면 퇴적물 상부 수주 전체 수심(2.6 m)에 대해 적산한 chlorophyll ${\alpha}$ 농도는 1.66(11월)${\sim}$11.7(7월) mg $m^{-2}$의 농도 범위로 평균 $6.96{\pm}3.04mg\;m^{-2}$를 나타내었다. 이로부터 갯벌 퇴적물 내에 존재하는 저서미세조류의 농도는 해수 중 존재하는 식물플랑크톤의 농도보다 3${\sim}$10배 정도 높은 것으로 추산되었다. 퇴적물과 상부 해수 중 미세조류의 농도에서 유사한 월별변화와 군집조성은 재부유된 저서미세조류가 광양만 해수 중 식물플랑크톤 생체량의 상당부분을 설명할 수 있음을 시사하였다. 따라서 이들 저서미세조류는 갯벌 생물뿐만 아니라 재부유에 의한 수송을 통하여 인근 연안 생태계의 생물군에 대한 중요한 영양원 역할을 할 수 있다는 점에서 이들의 거동에 대한 지속적인 관찰이 요구된다.

• 한국해양바이오학회지
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• 제12권1호
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• pp.40-49
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• 2020

This article emphasized the physiological characteristics of the selected marine microalgal strains obtained from the culture collection of the National Marine Biodiversity Institute of Korea (MABIK). Therefore, in this study, 13 different marine microalgal strains belonging to the phylum Chlorophyta were analyzed for the composition of fatty acids, elements, photosynthetic pigments, and monosaccharides, as well as the lipid and protein contents. The results presented that the primary fatty acids were palmitic (C_16:0), palmitoleic (C_16:1 n-7), stearic (C_18:0), oleic (C_18:1 n-9), linoleic (C_18:2 n-6), and α-linolenic (ALA, C_18:3 n-3) acid in the evaluated microalgae. The lipid contents of heterotrophically grown strains ranged from 15.1% to 20.4%. The calorific values of the strains were between 17.4 MJ kg^-1 and 21.3 MJ kg^-1. The major monosaccharides were galactose, glucose, and mannose, while the primary photosynthetic pigments were chlorophyll-a (Chla), chlorophyll-b (Chlb), and lutein, respectively. Based on the results, the microalgal strains showed high potentials in the use of microalgae-based technologies to produce biochemicals, food, and renewable fuels as they are rich in sustainable sources of high-value bio-compounds, such as antioxidants, carbohydrates, and fatty acids.