• Journal of Applied Biological Chemistry
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• v.54 no.4
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• pp.296-302
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• 2011

Insect-resistant transgenic rice was developed by inserting the mCry1Ac1 a modified gene from the soil bacterium Bacillus thuringiensis (Bt). For biosafety assessment, we studied the effects on survival of cantor Daphnia magna, a commonly used as a model organism in ecotoxicological studies. D. magna fed on Bt rice and its near non-genetically modified (GM) counterparts (Nakdong) grown in the same environment (100% ground rice suspension). The Bt rice was comfirmed to have the insertion of T-DNA and protein expression by the polymerase chain reaction and ELISA analysis. Feeding study showed similar cumulative immobility and abnormal response of D. magna between Bt rice and non-GM counterparts. 48 h-$EC_{50}$ values of Bt rice and non-GM rice showed 4,429 and 2,889 mg/L respectively. The rice no observed effect concentration (NOEC) values for D. magna was suggested 1,000 mg/L. We conclude that the tested Bt-rice and Nakdong similar cumulative immobility for D. magna the widely used model organism. We found out that there is strong possibility that the growth of Bt rice didn't affect to non-target insects.

• Journal of Environmental Health Sciences
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• v.39 no.4
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• pp.369-375
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• 2013

Objectives: This study was conducted to identify factors determining the toxicity of manufactured silver nano-particles (AgNPs) on aquatic organisms. Methods: For this purpose, we prepared several AgNPs with varied characteristics, including hydrodynamic size (nano-$^{ABC}Ag^{Cit}\;vs$-sized-$^{ABC}Ag^{Cit}$), impurities ($^{ABC}Ag$ stock vs $^{ABC}Ag$), and citrate capping ($^{ABC}Ag^{Cit}$), using a commercially available manufactured AgNP ($^{ABC}Ag$ stock). Acute tests were conducted using larval zebrafish (Danio rerioI). In addition, in order to determine the ecotoxicological potentials of various capping agents, toxicity tests were conducted with microbes, waterfleas, and fish for eight different capping agents that are used for NPs. Results: The toxicity of AgNPs in terms of 96 h fish $LC_{50}$ increased in the following order: $^{ABC}Ag$ stock < $^{ABC}Ag=^{ABC}Ag^{Cit}=nano-^{ABC}Ag^{Cit}$ < ${\mu}$-sized-$^{ABC}Ag^{Cit}$ < $AgNO_3$. After removing impurities by dialysis, 96 h $LC_{50}$ value decreased significantly from $126.6{\mu}g/L$ (95% confidence intervals [CI]: 107.0-146.2) ($^{ABC}Ag$ stock) to $78.6{\mu}g/L$ (CI: 72.7-84.8) ($^{ABC}Ag$). For ${\mu}$-sized-$^{ABC}Ag^{Cit}$ (ranging between 3.9 and 40.6 nm) and $^{ABC}Ag^{Cit}$ (40.6 nm and $9.1{\mu}m$), the 96 h $LC_{50}$ of the former ($43.9{\mu}g/L$, CI: 36.0-51.7) was approximately two-fold lower than that of the latter ($87.0{\mu}g/L$, CI: 73.5-100.3). Conclusions: In this study, we found that for acute lethality, the contribution of impurities and particle size was significant, but that of citrate was negligible.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.90-97
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• 2008

The aim of this research was to detect and observe delivering generation effects from $F_0$ generation exposed to 4-nonylphenol 4NP) to $F_1$ generation on Tigriopus japonicus. The nauplius survival rate of $F_1$ from $F_0$ exposed to low 4NP concentration was significantly lower than other concentrations. Among the developmental process, copepodite first emergence day (CE) and adult male first emergence day (ME) on $F_1$ were accelerated relatively high concentration conditions. The sex ratio of $F_1$ was different between control group and treatment groups for 1, 10 and $30{\mu}g\;L^{-1}$ 4NP. The fecundity of $F_1$ was not significantly affected (except, $0.1{\mu}g\;L^{-1}$ 4NP). When 4NP concentrations were increased, first brooding day (FB) of F 1 was generally delayed. The length, width, and biomass of $F_1$ adult female were smaller than control group. In addition, the width and biomass of adult male were narrower or smaller than control group.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.266-273
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• 2019

Heavy metal contamination in freshwater ecosystem has been receiving increased worldwide attention due to their direct or indirect effect on human health and aquatic organisms. In this study, we investigated biological effects such as survival rate, growth rate, emergence rate, sex ratio and mouthpart deformity of Chironomus plumosus. The survival rate of C. plumosus decreased with the increase in heavy metal concentration as well as exposure time after cadmium (Cd) or zinc (Zn) exposure. The growth rate decreased at days 4 and 7 after Cd exposure and significantly reduced at the relatively high concentration of $50mg\;L^{-1}$ Cd. The emergence rate was decreased at $50mg\;L^{-1}$ Cd and $100mg\;L^{-1}$ Zn. The sex ratio showed imbalance pattern at relatively low concentrations (0.5 and $2mg\;L^{-1}$ Cd) with high proportion of male and relatively high concentration ($100mg\;L^{-1}$ Zn) with high proportion of female (60%). In addition, mentum deformities were observed at high concentration of Cd and Zn. These results suggest that heavy metal exposure in aquatic ecosystem may affect biological and morphological responses, and aquatic midge C. plumosus is a potential indicator for assessment of environmental pollutant such as heavy metals.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.265-271
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• 2021

Intertidal mud crab (Macrophthalmus japonicus) is an organism with a hard chitinous exoskeleton and has function for an osmotic control in response to the salinity gradient of seawater. Crustacean exoskeletons change in their natural state in response to environmental factors, such as changes in the pH and water temperature, and the presence of pollutant substances and pathogen infection. In this study, the ecotoxicological effects of irgarol exposure and heavy metal distribution were presented by analyzing the surface roughness of the crab exoskeleton. The exoskeleton surface roughness and variation reduced in M. japonicus exposed to irgarol. In addition, it was confirmed that the surface roughness and variation were changed in the field M. japonicus crab according to the distribution of toxic heavy metals(Cd, Pb, Hg) in marine sediments. This change in the surface roughness of the exoskeleton represents a new end-point of the biological response of the crab according to external environmental stressors. This suggests that it may affect the functional aspects of exoskeleton protection, support, and transport. This approach can be utilized as a useful method for monitoring the aquatic environment as an integrated technology of mechanical engineering and biology.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.570-577
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• 2011

We developed insect-resistant GM rice(Bt transgenic rice) by inserting the mCry1Ac1 a modified gene from the soil bacterium, Bacillus thuringiensis. The Bt transgenic rice expressing the Bttoxin mCry1Ac1 was tested for the effects on survival of Misgurnus anguillicaudatus and Cyprinus carpio, commonly used as a model organism in ecotoxicological studies. M. anguillicaudatus and C. carpio fed 100% ground rice in suspension, using either Bt rice or non-GM counterpart rice(Nakdong). The Bt rice used for the test were confirmed to have the mCry1Ac1 gene expression by the immuno-strip and ELISA analysis. Feeding test showed that no significant differences in cumulative immobility and abnormal response of M. anguillicaudatus and C. carpio fed on between Bt rice and non-GM counterpart rice. The 96hr-LC₅₀ values showed no difference between Bt rice(>1,000mg/L) and non-GM rice(>1,000mg/L). We concluded that there was no significant difference in toxicity for non-target organisms(M. anguillicaudatus and C. carpio) between Bt rice and non-GM counterparts.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.207-215
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• 2020

Toxic assessment of antifouling agents (diuron and irgarol) was conducted using the fertilization and the normal embryogenesis rates of the sea urchin, Mesocentrotus nudus. Bioassessment began with male and female reproductive cell induction. White or cream-colored male gametes(sperm) and yellow or orange-colored female gametes (eggs) were acquired and fully washed, separately. Then, the fertilization and normal embryogenesis rates were measured after 10 min and 48 h of exposure to the toxicants, respectively. The fertilization and embryo development rates were greater than 90% in the control, validating the suitability of both endpoints. The normal embryogenesis rates were significantly decreased with increasing concentrations of diuron and irgarol, but no changes in the fertilization rates were observed in concentrations ranging from 0 to 40 mg L^-1. The EC₅₀ values of diuron and irgarol for the normal embryogenesis rates were 20.07 mg L^-1 and 22.45 mg L^-1, respectively. The no observed effect concentrations (NOEC) were <1.25 mg L^-1 and the lowest observed effect concentrations (LOEC) were 1.25 mg L^-1 and 2.5 mg L^-1, respectively. From these results, concentrations of diuron and irgarol over 1.25 mg L^-1 and 2.5 mg L^-1, respectively, can be considered to have toxic effects on invertebrates, including M. nudus. The ecotoxicological bioassay in this study using the noted fertilization and normal embryogenesis rates of M. nudus can be used as baseline data for the continued establishment of environmental quality standards for the effects of antifouling agents(especially diuron and irgarol) in a marine environment.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.430-439
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• 2023

UV and O₃ are materials used in the water treatment process, and many studies have been reported to remove organic matters, contaminants, and microorganisms. In this study, we were investigated effects of Chirnomidae (Chironomus flaviplumus, Chironomus riparius), which are contamination indicator species to exposure UV and O₃ for the survival rate, body color change and gene expression response. The survival rate of C. flaviplumus exposed to UV decreased to about 70% after 24 hours, and C. riparius about 50%. There was no change in the survival rate of C. flaviplumus exposed to O₃, and C. riparius decreased to 95% after 10 minutes of exposure, but there was no change during the subsequent exposure time. In addition, UV and O₃ exposure to the two species in body color faded in a time-dependent. In the HSP70 gene expression, C. riparius showed an increase in expression after UV exposure compared to the control group, and a significant difference was shown 12 hours after exposure (P<0.05). C. flaviplumus exposed to O₃ showed a relatively low expression compared to the control group, and showed a significant difference at 10 minutes and 1 hour after exposure (P<0.05). These results reported the ecotoxicological effects on Chironomidae according to UV and O₃ exposure. Therefore, the results of this study can be used as basic data to understand the effects of UV and O₃, which are disinfectants used in water treatment plants, on Chirnomidae entering plants.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.286-294
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• 2014

The purpose of this study is to investigate the effects of applying density current generator (hereafter referred to as DCG to large lakes on the operating conditions of DCG, de-stratification, water quality improvement and inhibition of algae occurrence. As a result of a survey conducted to derive the optimum operating parameters of DCG in a condition to minimize eco-toxicity, the following conclusions were obtained. During the survey period, a marked stratification appeared in September to October 2011 and May 2012. At this time, the average depth of water to form thermocline was found to be $5{\pm}2$ m, so the location of discharge port for the operation of DCG was determined to be about 5 m below from the surface. To minimize the adverse effects of benthos and obtain the effect of water mixture at the time of water circulation, the mixing ratio of surface water and deep water was designed to be 3:1 by means of ecotoxicological assessment on the DCG operating characteristics. To select the appropriate operating hours for DCG, DCG was operated by 12 hr, 24 hr, 36 hr and 48 hr. As its result, the formation of thermocline did not occur during the operation of 36 hr. Also, It was effected that start reoperating from 3rd day after stop 2days under the condition of operated during 36 hr with calculated power consumption. Under the above conditions, the results of DO and water temperature analysis during the operation of DCG showed that the stratification, which was distinct previously, appeared to be weak, and relatively lower levels than those before operation were found as a result of water quality analysis on COD and chlorophyll-a, which leads to the conclusion that the water body is maintained at a stable condition due to the circulation of water by the occurrence of density current resulting from the operation of DCG.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.203-214
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• 2018

Ballast water treated by sodium dichloroisocyanurate (NaDCC) injection method in ballast water management system (BWMS) contains reactive bromine, chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on the marine environment. WET testing was carried out for eight marine and fresh water organisms, i.e. diatom, Skeletonema costatum, Navicula pelliculosa, green algae, Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer, Brachionus plicatilis, Brachionus calyciflorus and fish, Cyprinodon variegatus, Pimephales promelas. The WET test revealed that diatom and green algae were the only organisms that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50 % (EC50) values of 25.0 %, 50.0 % and over 100.0 %, respectively, in seawater conditions. In contrast, rotifer and fish showed no toxicities to the effluent in the all salinity conditions. Meanwhile, chemical analysis revealed that the BWMS effluent contained total of 25 DBPs such as bromate, isocyanuric acid, formaldehyde, chloropicrin, trihalomethanes (THMs), halogenated acetonitriles (HANs) and halogenated acetic acids (HAAs). Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the all DBPs did not exceed 1.0 for general harbour environments, but isocyanuric acid, tribromomethane, chloropicrin and monochloroacetic acid exceed 1.0 for near ship environments. However, when NOEC (25.0%) of the WET test results where actual effluent was applied, it was concluded that the NaDCC injection method did not have unacceptable ecological risks to the general harbor including near ship environments.