• Journal of the korean society of oceanography
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• 제34권1호
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• pp.49-57
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• 1999

A red tide organism, Amphidinium carterae was incubated under different iron/chelator and nitrate concentrations to investigate the factors controlling the growth. The chelation capacity played a critical role in regulating the nitrate reductase (NR) activity and in vivo fluorescence of this organism. However, there was a significant difference between the NR activity and in vivo fluorescence in response to trace metals and chelator treatments. In vivo fluorescence was the highest in FeEDTA 10 ${\mu}$M treatments and the lowest in DTPA 10 ${\mu}$M treatments. This indicates that the availability of the trace metal is important in regulating the in vivo fluorescence of this photosynthetic microalgae In contrast, NR activity showed the highest values in trace metal enriched treatments, and trace metal + DTPA treatments showed fairly high NR activities. This suggests that DTPA treatment did not hinder the NR activity as much as it did in vivo fluorescence. In vivo fluorescence and NR activity increased with nitrate concentration of up to 50 ${\mu}$M and remained relatively constant or the rate of increase decreased above that concentration, indicating that initial nitrate concentration of higher than a certain level would not accelerate the growth of A. carterae. Further investigation is needed to elucidate the reason for the difference in timing sequence between the NR and in vivo fluorescence in response to different metal treatments and chelation capacity.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권1호
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• pp.11-21
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• 1999

The effect of sulfite on barley seedlings was investigated through Chl content, the electron transport activity of the photosystem, and Chl fluorescence. Barley leaves were harvested every 12 hrs during greening periods, and were then treated with a sulfite solution in either light or dark conditions. In both cases, the Chl content decreased in comparison with the control at any greening period. After sulfite treatment in the light, the activity of PS I decreased slightly, yet that of PSII showed a decrease of about 15%. The values of Fv, qP and qE decreased, however, the value of ql increased compared with the control. In addition, the value of qE decreased in leaves greened more than 12 hrs compared with that of the control. This indicates that the photosynthetic complex involved in energy dependent fluorescence quenching is undeveloped in a 12 hrs greened leaf, accordingly, it was a hardly affected by sulfite. After sulfite treatment in the dark, the activities of PSII and PSI decreased slightly, there was a small change in the value of Fv, qP decreased, and qE and the ratio of qNP/q increased in comparison with the control. As a result, PSII and PSI were not inhibited, however, the redox of QA was inhibited, and the excited energy was lost through the nonphotochemical pathway. The effects of sulfite in light or dark conditions were not considerably different with the Chl fluorescence quenching analysis method. In both light and dark conditions, the value of qP significantly decreased with sulfite compared to that of the control. This implies that the redox of QA was inhibited by sulfite in both light and dark contions.

• 식물조직배양학회지
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• 제27권4호
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• pp.339-343
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• 2000

When plants are exposed to subfreezing temperatures ice crystals are forming within extracelluar space in leaves. The growth of ice crystal is closely related to the degree of freezing injury. It was shown that an antifreeze protein binds to an ice nucleator through hydrogen bonds to prevent growth of ice crystal and also reduces freezing damage. The antifreeze proteins in plants are similar to PR proteins but only the PR proteins induced upon cold acclimation were shown to have dual functions in antifreezing as well as antifungal activities. Three of the genes encoded for CLP, GLP, and TLP were isolated from barley and Kentucky bluegrass based on amino acid sequence revealed after purification and low temperature-inducibility as shown in analysis of the protein. The deduced amino acid of the genes cloned showed a signal for secretion into extracellular space where the antifreezing activity sup-posed to work. The western analysis using the antisera raised against the antifreeze proteins showed a positive correlation between the amount of the protein and the level of freeze tolerance among different cultivars of barely. Besides it was revealed that TLP is responsible for a freeze tolerance induced by a treatment of trinexapac ethyl in Kentucky bluegrass. Analysis of an overwintering wild rice, Oryza rufipogon also showed that an acquisition of freeze tolerance relied on accumulation of the protein similar to CLP. The more direct evidence for the role of CLP in freeze tolerance was made with the analysis of the transgenic tobacco showing extracellular accumulation of CLP and enhanced freeze tolerance measured by amount of ion leakage and rate of photosynthetic electron transport upon freezing. These antifreeze proteins genes will be good candidates for transformation into crops such as lettuce and strawberry to develop into the new crops capable of freeze-storage and such as rose and grape to enhance a freeze tolerance for a safe survival during winter.

• 환경생물
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• 제18권1호
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• pp.63-67
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• 2000

$Cd^2+$이 닭의장풀의 엽록소 함유량, 기공 크기, 수분퍼텐셜, 이온 수송에 대한 효과와 기관내의 카드뮴의 축적에 대하여 조사하였다. 3주간 성장한 닭의장풀을 Hoagland용액(${\pm}5mM Cd^2+$)에서 4일 동안 수경배양하였다. 카드뮴은 식물의 뿌리, 줄기 그리고 잎 등 모든 기관에 축적되었다. 뿌리로부터의 거리와 잎의 나이 등이 카드뮴 분포를 결정짓는 가장 중요한 요소였다. 대부분의 $Cd^2+$이 뿌리로부터 가장 인접한 성숙한 첫 번째 잎에 축적되었다. 잎에 $Cd^2+$의 축적은 여러 생리적인 대사의 활성에 감소를 가져왔다. 카드뮴 처리는 70%의 엽록소 함량 감소를 가져왔으며, 엽록소 a/b비도 2로 감소하였다. $Cd^2+$은 또한 20%의 수분퍼텐셜을 감소시켰다. 카드뮴 처리는 여러 광도(100-l,000$\mu$mol $Em^-2s^-1$)에서 광합성 활성을 약 60% 감소시켰으며 기공전도도도 비슷한 반응을 보였다. 따라서, $Cd^2+$이 닭의장풀의 전반적인 생리적 활성을 감소시키거나 차단하는 것으로 추측된다.

• Journal of Ecology and Environment
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• 제35권4호
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• pp.279-289
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• 2012

This study conducted a comparative analysis of benthic macroinvertebrate communities in the Fosu and Benya lagoons in Ghana, based on the anthropogenic effect on the two lagoons. Salinity, oxygen, temperature, conductivity, turbidity and pH were measured, invertebrate richness and species densities were determined. The AZTI Marine Biotic Index (AMBI) and multivariate statistics were used to determine the different responses of fauna to pollution. The fauna were categorized into five ecological groups based on the degree of tolerance of the different species to pollution: disturbance-sensitive species; disturbance-indifferent species, disturbance-tolerant species, second-order opportunistic species; and first-order opportunistic species. The Fosu Lagoon supported more pollution tolerant species, whereas the Benya Lagoon had more species that were sensitive to organic enrichment under relatively unpolluted conditions. Chironomus sp., which is adapted to virtually anoxic conditions, was the most abundant in the Fosu Lagoon whereas Nemertea sp. was the most abundant in the Benya Lagoon. The numerical and relative abundance (%) of all 7 taxa in the Fosu Lagoon was 1,359 and 92.35%, respectively. The numerical and relative abundance (%) of all 34 taxa in the Benya Lagoon was 2,459 and 87.52%, respectively. Expectedly, the level of dissolved oxygen in the less saline Fosu Lagoon was higher than that in the more saline Benya Lagoon. The reduced photoperiod and photosynthetic activities of aquatic plants might account for this trend. There is a need to implement comprehensive monitoring and management initiatives for sustaining the ecological health of coastal lagoons in Ghana in order to support the many people that depend upon these ecosystems for their livelihood.

• 한국작물학회지
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• 제52권2호
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• pp.153-161
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• 2007

Field experiments were conducted to determine the physiological and biochemical basis of the interactive effect of sulphur (S) and nitrogen (N) application on seed and xanthotoxin yield of Ammi majus L. Six treatments were tested ($T_1$ = control-without manure and fertilizers, $T_2$ = manure @ 9 kg $plot^{-1}-10\;t\;ha^{-1},\;T_3=A_0N_{50}K_{25}P_{25},\;T_4=S_{40}N_{50}K_{25}P_{25},\;T_5=S_{40}N_{100}K_{25}P_{25}\;T_6=S_{20+20}N_{50+50}K_{25}P_{25})$). Nitrate reductase (NR) activity and ATP-sulphurylase activity in the leaves were measured at various phonological stages, as the two enzymes catalyze rate-limiting steps of the assimilatory pathways of nitrate and sulphate, respectively. The activities of these two enzymes were strongly correlated with seed and xanthotoxin yield. The highest nitrate reductase activity, ATP-sulphurylase activity and xanthotoxin yield were achieved with the treatment $T_4$. Any variation from this treatment decreased the activity of these enzymes, resulting in a reduction of the seed and xanthotoxin yield in Ammi majus L. The higher seed and xanthotoxin yield achieved in Ammi majus L. at treatment $T_4$ could be due to optimization of leaf soluble protein and photosynthetic rate, as these parameters are Influenced by S and N assimilation.

• Journal of Microbiology
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• 제44권3호
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• pp.284-292
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• 2006

The cbb3 cytochrome c oxidase has the dual function as a terminal oxidase and oxygen sensor in the photosynthetic bacterium, Rhodobacter sphaeroides. The cbb3 oxidase forms a signal transduction pathway together with the PrrBA two-component system that controls photosynthesis gene expression in response to changes in oxygen tension in the environment. Under aerobic conditions the cbb3 oxidase generates an inhibitory signal, which shifts the equilibrium of PrrB kinase/phosphatase activities towards the phosphatase mode. Photosynthesis genes are thereby turned off under aerobic conditions. The catalytic subunit (CcoN) of the R. sphaeroides cbb3 oxidase contains five histidine residues (H2l4, B233, H303, H320, and H444) that are conserved in all CcoN subunits of the cbb3 oxidase, but not in the catalytic subunits of other members of copper-heme superfamily oxidases. H214A mutation of CcoN affected neither catalytic activity nor sensory (signaling) function of the cbb3 oxidase, whereas H320A mutation led to almost complete loss of both catalytic activity and sensory function of the cbb3 oxidase. H233V and H444A mutations brought about the partial loss of catalytic activity and sensory function of the cbb3 oxidase. Interestingly, the H303A mutant form of the cbb3 oxidase retains the catalytic function as a cytochrome c oxidase as compared to the wild-type oxidase, while it is defective in signaling function as an oxygen sensor. H303 appears to be implicated in either signal sensing or generation of the inhibitory signal to the PrrBA two-component system.

• 한국초지조사료학회지
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• 제42권4호
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• pp.222-228
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• 2022

This study was conducted to investigate the effect of waterlogging stress on the physiological response and growth characteristics of the five Italian ryegrass varieties. For all varieties, the germination rate of seed decreased by 10-15% as the waterlogging period increased, but the waterlogging stress treatment after the early seedling stage increased the growth of shoot and root length. Photosynthetic activity (Fv/Fm) according to waterlogging stress treatment decreased in all vareity, and Florida 80 showed the least decrease with 1.5%. Waterlogging stress treatment was found to reduce the accumulation of reactive oxygen species (malondialdehyde, MDA) and the activities of antioxidant enzymes. These results suggest that other mechanisms may be involved in the defense mechanism of Italian ryegrass against waterlogging stress, such as promoting root growth to escape from waterlogging stress, in addition to the antioxidant enzyme system.

• 한국해양생명과학회지
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• 제9권1호
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• pp.47-52
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• 2024

Light is a major external environmental factor that influences the circadian rhythm of photosynthetic organisms and various physiological phenomena, such as growth, maturation, and behavior. The number of light-reaching organisms changes depending on the season and atmospheric conditions, and the intensity and wavelength of light differ depending on the organisms inhabiting the environment. Altered light changes the circadian rhythm of fish, which is controlled by clock genes, such as period 2 (Per2), cryptochrome 1 (Cry1), and melatonin. In this study, we set the zeitgeber time (ZT; 14 light-10 dark, LD) based on the actual sunrise and sunset times and examined Per2 and Cry1 activities, levels of aralkylamine N-acetyltransferase (AANAT), and melatonin in Pholis nebulosa, a drifting seaweed species exposed to irregular light. Per2 and Cry1 levels increased during the daytime and decreased after sunset. The AANAT levels decreased during the daytime and increased during the night. Melatonin concentration was highest around midnight (ZT21, 23:30), but exhibited similar concentrations during the daytime. While the activity of Per2, Cry1, and AANAT levels exhibited a typical circadian rhythm observed in most vertebrates, melatonin concentrations did not show a significant difference between the daytime and nighttime. These findings provide insights into the circadian rhythm patterns of organisms exposed to irregular light environments, such as P. nebulosa, which differ from those of typical fish species.

• 생물환경조절학회지
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• 제13권4호
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• pp.226-232
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• 2004

착색단고추 동계재배시 주${\cdot}$야 온도관리방법 차이에 의한 환경변화가 생육 및 수량에 미치는 영향을 구명코자 하였다. 수량은 품종 간에는 'Fiesta'가 'Jubilee' 보다 총수량은 많았으나 상품률이 떨어져 상품수량은 차이가 없었고, 평균과중도 차이가 없었다. 품종간 총 수량 차이의 주원인은 착과수, 수확개시기 및 뿌리상태의 차이였고, 상품률 저하의 주요인은 열과발생률 차이였다. 야간온도 간에는 $18^{\circ}C$가 $15^{\circ}C$에 비해 총수량이 많은데다 상품률도 높아서 상품수량은 현저하게 많았으나 과중은 $15^{\circ}C$가 다순 무거웠다. 야간온도 간의 수량차이의 주요인도 착과수와 수확개시기의 차이였다. 주간온도 간에는 $28^{\circ}C$와 $31^{\circ}C$는 차이가 없었으나 $34^{\circ}C$는 이산화탄소 농도저하 및 고온다습으로 인해 영양생장이 촉진되었고, 엽록소 함량도 가장 적었다. 따라서 총수량 및 상품수량이 현저하게 적었고 평균과중도 가벼웠다. 본 시험에서 처리한 주${\cdot}$야 온도는 개엽의 광합성률, 증산률, 엽록소형광, 항산화효소 활성 등에 영향을 미치지 않았으나 통계적인 오차범위 내의 근소한 차이들이 어떤 식으로든 광합성능력에 영향을 미쳤을 것임은 분명하다. 주간고온에 의한 야간저온 보상효과는 없었다.