• 한국환경과학회지
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• 제16권4호
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• pp.425-432
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• 2007

The water flea has been used as a test organism of toxicity test for surface water. Toxicity test with water flea is categorized into two parts. One is acute toxicity test with observing immobility and mortality and the other is chronic toxicity test determined by survival and reproduction of water flea. Heartbeat measurement of water flea was designed as a short-term toxicity test in this study. Direct measurement of heartbeat under microscope by aid of video camera gives and early diagnosis of mortality in short time. Therefore, the effects of measuring illumination, measuring time, and non-feeding during the test on heartbeat of water flea was evaluated to establish a new test approach. Test organisms used in this study are Daphnia magna, a well standardizes toxicity test organism, and Simocephalus mixtus, a newly refined organism $IC_{50}$ values of these test organism by heartbeat measurement were compared and discussed. It was found that toxicity test by heartbeat measurement was a reproducible, easy and simple method accomplished in a few hours.

• 한국해양생명과학회지
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• 제8권1호
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• pp.78-86
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• 2023

Here, upon acute (96 h) and chronic (14 days) exposure, ingestion of polystyrene NPs (100 nm) and physiological, biochemical, and cholinergic modulations were analyzed in the water flea Moina macrocopa exposed to different concentrations (0.001, 0.01, 0.1, 1, 5, 10, 50, 100, and 500 ㎍ l^-1). Exposed NPs were observed in the internal organs (e.g., digestive tract and foregut) of the water flea. Chronic exposure to the relatively high concentrations resulted in significant decreases in survival, body length, and the total number of molts, whereas reproduction parameter was not affected. Significant increase in oxidative stress biomarker (malondialdehyde) and decrease in the intracellular content of endogenous antioxidant (glutathione) and enzymatic activity of antioxidant enzymes (glutathione peroxidase, glutathione reductase, catalase, superoxide dismutase, and glutathione S-transferase) were detected in response to relatively high concentrations of NPs. Transcriptional expression of the hsp70 gene was increased in response to relatively high concentrations of NPs, whereas acetylcholinesterase activity was lowered by the same concentrations of NPs. Taken together, NPs exposure would be a significant modulator on physiological and biochemical metabolism of water flea.

• Journal of information and communication convergence engineering
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• 제4권2호
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• pp.92-96
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• 2006

Hardware for monitoring the water quality using water fleas is developed. Water flea is a frequently used biological sensor for monitoring the water quality. Water fleas quickly respond to the incoming toxic water by changing their activity when they are exposed. By measuring the activity of water fleas, the incoming toxic water is instantly detected. So far the measurement of activity of water fleas has been done with a system equipped with both a light source of LED and a light detector of photo transistor. Water flea itself is, however, sensitive to light resulting in incorrect response and the system has two inconvenient separate parts of the light source and the detector. This paper suggests a system using a CCD camera instead of a light source and a detector. The suggested system processes the image data from the CCD camera in real time without any delay. The developed system becomes a part of the remote water monitoring embedded system.

• 전자공학회논문지SC
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• 제44권5호
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• pp.30-37
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• 2007

수질 감시를 위한 물벼룩 활동량 측정을 실시간으로 측정하는 하드웨어를 구현 하였다. 물벼룩은 수질 감시에 빈번히 시용하는 살아있는 생물학적 센서라고 할 수 있다. 물벼룩은 수질이 오염이 되면 활동량의 변화가 나타나기 때문에 물벼룩의 활동량을 감시함으로서 해당 수질의 독성 물질의 유입을 즉각 확인할 수 있다. 물벼룩의 활동량 조사는 기존의 방법은 LED를 이용한 발광부와 Photo TR.을 이용한 수광부를 사용하는 방법이 있으나 물벼룩이 빛에 민감하게 반응하고 측정 대상인 물벼룩을 기준에 두고 2 개의 장치(발광부와 수광부)를 두는 불편한 점이 있었다. 본 논문은 기존의 방식을 대체하기 위해 CCD 카메라를 사용한다. CCD 카메라의 영상처리를 위해 이미지 버퍼에 저장한 후 컴퓨터나 DSP를 사용하여 소프트웨어로 일괄 처리를 하는 것이 아니라 실시간으로 하드웨어로 처리하는 시스템을 구현하였다. 그리고 구현된 하드웨어로 수질 경보를 위한 원격 모니터링 임베디드 시스템을 구축하였다.

• 한국수산과학회지
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• 제43권2호
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• pp.131-138
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• 2010

This study determined the optimum microalgae species and concentration for the brackish water flea, Diaphanosoma celebensis, in individual and community cultures by feeding it several different diets. Six single trials (Tetraselmis suecica, Isochrysis galbana, marine Chlorella ellipsoidea, freshwater Chlorella vulgaris, Scenedesmus sp., Selenastrum sp.) were conducted at 10 psu and $30^{\circ}C$. The community and individual cultures of the water flea were performed in 1-L beakers and 3-mL vessels (12-well culture plates), respectively. In the community cultures, the maximum density and specific growth rate were highest for water fleas fed T. suecica, reaching 60.0 individuals (ind.)/mL and 0.40, respectively. In the individual cultures, the most offspring and greatest life span of females were 56.9 ind. and 24.3 days, respectively, in the T. suecica trial. By contrast, diets of Scenedesmus sp. and Selenastrum sp. resulted in poor growth rates. In the T. suecica experiments examining a range of 10 to $200\times10^3$ cells/indl. the specific growth rate of the water flea tended to increase with the amount of supplement, while the life span decreased. The maximum density and number of offspring of females was highest at 53.5 ind./mL and 38.8 ind. respectively, at 40,000 cells/ind. These results suggest that the best microalgae species for the mass culture of D. celebensis is T. suecica and the optimum concentration is 40,000 cells per individual.

• 한국물환경학회지
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• 제26권4호
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• pp.566-573
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• 2010

Nanotechnology has been applied to various fields in our life. Although there is a limitation of nanoparticle monitoring so far, it is expected that nanoparticles are widely distributed in environmental multimedia. Nanoparticle is known to be more toxic than its corresponding bulk material. For this reason, developed countries and international organizations are preparing for future regulation. To evaluate the safety of nanoparticles, nanotoxicity studies are internationally underway. In this study, we evaluated the research trends of ecotoxicity of nanoparticles in water environment. Test species include fish, water flea, and algae. Nanoecotoxicological studies are rapidly increasing and the experimental designs become more sophisticated. Physicochemical properties of nanoparticles should be measured and the ionization potential is important for metal-based nanoparticles. We analyzed the research trends based on the type of nanoparticles and test species. Also experimental aspects of nanoecotoxicology are considered.

• 환경생물
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• 제39권2호
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• pp.160-168
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• 2021

Doublesex and mab-3 related transcription factor(dmrt) play crucial roles in sex determination and sex differentiation in vertebrates and invertebrates. Although dmrt genes have been identified in vertebrates, little is known about aquatic invertebrates. In this study, two dmrt genes, namely, Dc_dmrt93B and Dc_dmrt99B, were identified from brackish water flea, Diaphanosoma celebensis. Transcriptional changes were observed in the dmrt genes when the flea was exposed to bisphenol(BP), an endocrine disruptor. Sequence and phylogenetic analyses showed that both dmrt genes contained two conserved domains, namely, DM and DMA, closely clustered with those of Daphnia spp. Additionally, a significant increase in the Dc_dmrt99B mRNA expression level was observed upon exposure to intermediate concentrations of BP (bisphenol A>bisphenol S=bisphenol F, p<0.05), while the expression of Dc_dmrt93B mRNA was slightly modulated. These findings imply that the two dmrt genes may be involved in sex differentiation of D. celebensis. Furthermore, it was found that the ability of BP to modulate dmrt genes could affect development and reproduction. This study provides a basis for understanding the function of the dmrt genes and the molecular mode of action of BP in small crustaceans.

• 한국수산과학회지
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• 제43권2호
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• pp.139-145
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• 2010

This study investigated the optimum salinity and temperature conditions for mass culture of the brackish water flea, Diaphanosoma celebensis. Community and individual cultures of flea were maintained in 1 L beakers and 3 mL vessels (of a 12-well culture plate), respectively, and fed green algae, Tetraselmis suecica. In salinity experiments ranging from 5 to 34 psu, continuous growth of flea populations was found up to 34 psu. However, the specific growth rate and life span of females showed decreasing tendencies with the increase of salinity. The highest maximum density and offspring number were 33.6 individuals (ind.)/mL and 55.3 ind. at 10 psu, respectively. In the temperature experiments ranging from 20 to $40^{\circ}C$, population growth of D. celebensis increased continuously until $35^{\circ}C$ and then decreased over $40^{\circ}C$. The specific growth rate was significantly higher at 25 and $30^{\circ}C$ than at 20 and $40^{\circ}C$. Female life span tended to decrease with temperature increase. The highest maximum density and offspring number were 52.3 ind./mL and 46.0 ind. at $30^{\circ}C$, respectively. These results suggest that the optimum salinity and temperature for mass culture of D. celebensis may be 10 psu and $30^{\circ}C$, respectively.

• 생태와환경
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• 제36권2호통권103호
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• pp.208-214
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• 2003

국내산 물벼룩의 배양조건에 따른 개체 생산특성을 비교하고 최적 배양환경 조건을 도출하기 위하여 배양조건에 따른 물벼룩의 개체생산특성을 조사하였다. Daphnia magna, D. pulex, Moina macrocopa는 퇴비를 이용한 배양액으로 배양하는 것이 생존기간과 개체 발생 수 측면에서 가장 효과가 좋았으며 D. galeata는 이와는 달리 비료를 이용한 배양액에서 가장 성장률이 좋았다. D. galeata는 전반적으로 배양이 어려웠으며 배양기간 동안의 새끼 발생도 적어 인공 배양시에 상당한 관심이 요구되었다. 남조류 Microcystis sp.의 microcystin이라는 독소는 포유류를 비롯한 여러 생물에게 직접적인 영향을 미치는 것으로 밝혀졌으나 금번 실험에서는 물벼룩의 생존여부에 대해서는 독소의 영항이 크게 나타나지 않았다. 또한 남조류 Microcystis sp.를 공급받은 물벼룩은 제한된 먹이 제공으로 적은 양의 Microcystis sp.를 불가피하게 섭취함으로써 상대적으로 생존기간이 짧았으며 개체 생산율도 낮았다. Scenedesmus sp.를 먹이로 공급한 경우는 물벼룩의 종류와 배양액의 종류에 상관없이 Microcystis sp.를 먹이로 공급한 경우보다 생존기간이 길고 개체발생수도 많았다. 각 물벼룩은 $20^{\circ}C$에서보다 더 생존기간이 길고 더 많은 개체를 발생하여 물벼룩 배양은 $15^{\circ}C.$보다 $20^{\circ}C$가 적절함이 확인되었다. 이러한 결과를 토대로 볼 때 D. galeata와 M. macrocopa는 물벼룩을 이용한 수질감시와 독성실험에 사용하기에 어려움이 많은 종이며 기존에 사용하고 있는 D. magna와 국내에서도 분포하고 있는 D. pulex를 사용하는 것이 용이할 것으로 사료된다.

• 한국수산과학회지
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• 제46권4호
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• pp.393-398
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• 2013

The purpose of this study was to determine how an ornamental fish, such as the fighting fish, Betta splendens would respond to the use of freshwater live-prey, such as rotifers Brachionus calyciflorus and water fleas Moina macrocopa. Ingested quantity, digestive velocity and somatic growth were compared between larvae fed a freshwater rotifer and those fed boiled yolk. Food efficiency and somatic growth were compared between larvae that were fed freshwater water fleas and those fed a micro-diet developed for flounder ($250{\mu}m$, I-hwa Ltd.). The number of rotifers ingested by larvae reached a maximum of 191 per day. However, based on the number ingested per hour and the digestive velocity of consumed rotifers, the maximum ingestible and digestible number of rotifers was calculated to be 272 per day. A maximum of 67 individuals (mean, 49.8 individuals) could be completely digested within the 1-h period from 90 to 180 min after feeding. Somatic growth was enhanced in larvae that were fed rotifers compared to those fed boiled yolk. Larvae exhibited greater growth at rotifer densities of 30 and 40 per mL than at lower densities. Among the water-flea (M. macrocopa and Bosmina sp.) and micro-particle diets, feeding with M. macrocopa resulted in the greatest somatic growth of larvae during the water-flea feeding stage.