• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1453-1459
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• 2019

Zeaxanthin is an important pigment in the photo-protection mechanism of microalgae. However, zeaxanthin epoxidase, an enzyme involved in the accumulation and conversion of zeaxanthin, has not been extensively studied in microalgae. In this work, we report the expression pattern of zeaxanthin epoxidase in Dunaliella tertiolecta (DtZEP) at different light and diverse salinity conditions. To confirm the responsiveness to light conditions, the ZEP expression pattern was investigated in photoperiodic (16 h of light and 8 h of dark) and continuous (24 h of light and 0 h of dark) light conditions. mRNA expression levels in photoperiodic conditions fluctuated along with the light/dark cycle, whereas those in continuous light remained unchanged. In varying salinity conditions, the highest mRNA and protein levels were detected in cells cultured in 1.5 M NaCl, and ZEP expression levels in cells shifted from 0.6 M NaCl to 1.5 M NaCl increased gradually. These results show that mRNA expression of DtZEP responds rapidly to the light/dark cycle or increased salinity, whereas changes in protein synthesis do not occur within a short period. Taken together, we show that DtZEP gene expression responds rapidly to light irradiation and hyperosmotic stress. In addition, ZEP expression patterns in light or salinity conditions are similar to those of higher plants, even though the habitat of D. tertiolecta is different.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1155-1172
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• 2015

In this paper, we propose a novel saliency detection framework based on illumination invariant features to improve the accuracy of the saliency detection under the different light conditions. The proposed algorithm is divided into three steps. First, we extract the illuminant invariant features to reduce the effect of the illumination based on the local sensitive histograms. Second, a preliminary saliency map is obtained in the CIE Lab color space. Last, we use the region growing method to fuse the illuminant invariant features and the preliminary saliency map into a new framework. In addition, we integrate the information of spatial distinctness since the saliency objects are usually compact. The experiments on the benchmark dataset show that the proposed saliency detection framework outperforms the state-of-the-art algorithms in terms of different illuminants in the images.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.1
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• pp.25-32
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• 2016

This study deals with the light environments and weather conditions affecting to the night illuminance over the Korean peninsula. The experiment was executed to analyze the effects on the illuminance at separate sites(Gyeryong and Pilseung) considering the different light environments. The analysis was applied to illuminance measurement from the lightmeter, which was developed for the IYA(International Year of Astronomy) 2009, in order to observe the illuminance of areal networks. The weather observations, such as the cloud cover and visibility, were used to understand the quantitative influence of the illuminance to the selected sites. The results show that the illuminance measurements are significantly different from data of the operational illuminance prediction model which simply applies extinction effect for the illuminance. It shows that these differences are caused by the light environments and weather conditions for each site. Therefore, it can be confirmed that the night illuminance is the output of interaction with the characteristics of light for luminous sources.

• Horticultural Science & Technology
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• v.31 no.4
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• pp.400-406
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• 2013

This study was conducted to investigate the growth and flowering of African marigold (Tagetes erecta L.) and salvia (Salvia splendens F. Sello ex Ruem & Schult.) seedlings before and after storage under fluorescent lamps and green LED radiation conditions with different light intensities during storage. The both seedlings were kept under a storage room controlled at $8^{\circ}C$ air temperature and $40{\pm}10%$ relative humidity conditions. Light intensities were maintained at 15 and $30{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ during storage. In lighting treatments, dry weight of African marigold at 28 days after storage was not significantly different, and decreased approximately 29% compared to pre-storage under dark treatment. There was no significant difference in the leaf area of salvia seedlings stored under dark condition compared to before storage, but the leaf area under green light radiation with higher light intensity (treatment GH) was two times greater than before storage. The survival rate after transplanting of African marigold stored under dark condition was 10%, and days to flowering increased compared to those stored under fluorescent and green light with higher light intensity (treatment FLH, GH). Comparing to before storage, growth and flowering of the both seedlings after storage were significantly promoted by the light exposure during storage. The present experimental results show that the light intensity should be decided to maintain minimum growth during lighting storage and storage quality of the seedlings such as flowering promotion and extended blooming period after lighting treatment during storage period from the above results.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.3
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• pp.319-323
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• 2015

This study investigated the effects of the light conditions on the productivity of scenedesmus dimorphus in the continuous mass cultivation system. To compare the algal productivity according to the light conditions, S. dimorphus was cultivated continuously under the wide range of light intensity(200-600 PPFD) and various light wavelength(white light and red-blue mixed light). After 100 days of cultivation under the different light intensity, the productivity of S. dimorphus increased as light intensity decreased. So, the productivity was maximized as 100 mg/L/d when light intensity was 200 PPFD. In case of light wavelength, the productivity of S. dimorphus was enhanced about 20% with the white light compared to that of the red-blue mixed light. Consequently, the optimal light conditions for the continuous mass cultivation of S. dimorphus were 200 PPFD as light intensity and white light as light wavelength.

• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.125-133
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• 2014

The variation of glucosinolates (GSLs) in Chinese cabbage ('Sinhongssam') (Brassica rapa L. spp. pekinensis) cultivated under lights to control plant growth conditions was evaluated at different development stages. Under experimental conditions in plant factory system, plant growth conditions including light, temperature, and nutrients were designed to enhance GSLs. The variation of glucosinolates (GSLs) in Chinese cabbage ('Sinhongssam') (Brassica rapa L. spp. pekinensis) cultivated under lights to control plant growth conditions was evaluated at different development stages. Under experimental conditions in plant factory system, plant growth conditions including light, temperature, and nutrients were designed to enhance GSLs. The contents of GSLs were quantified in Chinese cabbage according to different light sources (Red+White, RW; Red+Blue+White, RBW, Fluorescence lamp, FL) at development stages (28, 42, and 56 days after sowing, DAS) using HPLC. Nine GSLs including five aliphatic (progoitrin, sinigrin, glucoalyssin, gluconapin, and glucobrassicanapin) three indolyl (glucobrassicin, 4-methoxyglucobrassicin, and neoglucobrassicin), and one aromatic (gluconasturtiin) GSLs were identified based on peak retention time in previous results of our laboratory. GSL contents were higher in RBW (36.55) and lower in FL ($15.24{\mu}mol/g/\;DW$). Results revealed that GSL contents were higher under controlled photoperiods (20/4 h) ($58.35{\mu}mol/g\;DW$) and controlled light intensity ($160{\mu}mol/m^2/s$) ($34.02{\mu}mol/g\;DW$), respectively. Lower amount of progoitrin and comparatively higher amount of glucobrassicin and gluconasturtiin was noted in Chinese cabbage cultivated under FL light (2.38, 9.82, and 2.10) at 42 DAS, photoperiod 20/4 h (3.16, 2.52, and 1.30) at 28 DAS, and light intensity at $130{\mu}mol/m^2/s$ (2.28, 2.24, and $1.51{\mu}mol/g\;DW$) at 42 DAS. Therefore FL light, photoperiod (20/4 h), and light intensity ($130{\mu}mol/m^2/s$) were considered as most suitable for the enhancement of GSLs in Chinese cabbage.

• Journal of Applied Biological Chemistry
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• v.59 no.2
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• pp.99-102
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• 2016

The phototactic behavioral responses of Tribolium castaneum adults to light-emitting diodes (LEDs) of seven different wavelengths were determined under various conditions (light exposure times, light sources, and luminance intensities) and compared with those of a black light bulb (BLB) under laboratory conditions. Based on the attractive rate (%) of T. castaneum adults under optimal conditions (50 lx and an 48 h exposure time) in the dark, red LED ($625{\pm}10nm$) exhibited the highest potential attractive rate (97.8 %), followed by yellow ($590{\pm}5nm$, 68.9 %), green ($520{\pm}5nm$, 55.6 %), infrared (IR) (730 nm, 54.4 %), white (450-620 nm, 41.1 %), blue ($470{\pm}10nm$, 34.4 %), and ultraviolet (UV) (365 nm, 0.06 %) LEDs. In comparison, red LED (97.8 %) was approximately 3.4 times more attractive to T. castaneum adults than the BLB (28.9 %). These results indicate that a red LED trap could be useful to control T. castaneum adults.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.475-483
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• 2015

The marine microalgae Isochrysis galbana was cultured under various light-emitting diode (LED) light conditions with different wavelengths to examine changes in growth and in amino acid and fatty acid profiles. The culture conditions for the microalgae were Conway medium, salinity of 33 psu, temperature of $24^{\circ}C$, and a 16/8 h light/dark photoperiod. Six light sources, including 5 units of 180W LED lamps (peak wavelength: blue [LB] 470 nm; green [LG] 525 nm; yellow [LY] 595 nm; red [LR] 636 nm; white [LW] 442 nm) and 1 unit of a 175W metal halide (MH) lamp, were used for the experiment. The dry cell weights ($gL^{-1}$) of I. galbana under different light conditions were in the order of LW>LB${\geq}$MH>LR>LG>LY. Levels of essential amino acids were revealed to be significantly higher under LW, LG, and MH than under the other wavelengths (P<0.05). The fatty acid, unsaturated fatty acid, and DHA contents of I. galbana were higher under MH, LW, and LG. In addition, the carotenoid content was higher under MH, LW, and LG than under the other wavelengths (P<0.05). The fucoxanthin content was highest under MH (0.28%) and lowest under LY (0.2%), and it was 0.26% under LW and LG. The results indicate that the combined use of LW and LG is effective when using LED lamps for I. galbana cultivation.

• ALGAE
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• v.32 no.2
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• pp.139-153
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• 2017

The ability of a red tide species to take up nutrients is a critical factor affecting its red tide dynamics and species competition. Nutrient uptake by red tide species has been conventionally measured by incubating nutrient-depleted cells for a short period at 1 or 2 light intensities. This method may be applicable to certain conditions under which cells remain in oligotrophic water for a long time and high nutrients are suddenly introduced. Thus, a new method should be developed that can be applicable to the conditions under which cells are maintained in eutrophicated waters in healthy conditions and experience light and dark cycles and different light intensities during vertical migration. In this study, a new repletion method reflecting these conditions was developed. The nitrate uptake rates of the red tide dinoflagellate Prorocentrum micans originally maintained in nitrate repletion and depletion conditions as a function of nitrate concentration were measured. With increasing light intensity from 10 to $100{\mu}E\;m^{-2}s^{-1}$, the maximum nitrate uptake rate ($V_{max}$) of P. micans increased from 3.6 to $10.8 pM\;cell^{-1}d^{-1}$ and the half saturation constant ($K_{s-NO3}$) increased from 4.1 to $6.9{\mu}M$. At $20{\mu}E\;m^{-2}s^{-1}$, the $V_{max}$ and $K_{s-NO3}$ of P. micans originally maintained in a nitrate repletion condition were similar to those maintained in a nitrate depletion condition. Thus, differences in cells under nutrient repletion and depletion conditions may not affect $K_{s-NO3}$ and $V_{max}$. Moreover, different light intensities may cause differences in the nitrate uptake of migratory phototrophic dinoflagellates.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.3
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• pp.245-257
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• 2020

Behavioral response to a diel photoperiodicity (500 lx for 16 h, 5 lx for 4 h and < 0.5 lx for 4 h) and phototactic characteristics in dark conditions were examined with Siberian sturgeon Acipenser baerii (Chondrostei, Actinopterygii) prelarvae. Siberian sturgeon prelarvae represented both qualitative and quantitative changes in their behavioral patterns according to different light intensities in a diel photoperiodicity. Under daylight conditions (500 lx), prelarvae displayed saltatory changes of behavioral features with ages (Day 0-Day 9) in a general order of swimming-up/drifting, swimming in the upper water column, benthic swimming with rheotaxis, schooling and post-schooling behavior. Compared to daylight conditions, prelarvae tended to show more benthic performances and quantitative reductions of schooling and post-schooling behaviors under dimlight conditions (5 lx). Under dark conditions (< 0.5 lx), prelarvae exhibited a fairly uniform behavioral pattern characterized by the benthic swimming across the bottom of the tank. From phototaxis tests under dark conditions, navigational responses of prelarvae to a spotlight illumination were quantitatively changed as their ages increased. The phototactic responses reached the peak on Day 2, continued until Day 4, and then gradually decreased until Day 8. A partial recovery of positive phototaxis was observed on Day 9. Data from this study suggest that the diel light cycle as well as the light intensity of each interval in the cycle should be considered as important components of a practical guide for evaluating fitness and developmental states of artificially propagated Siberian sturgeon prelarvae.