• Applied Microscopy
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• v.12 no.1
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• pp.23-32
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• 1982

Caulubacter is distinctive in the morphology and replication and ubiquitous in the biosphere, especially in every type of aquatic environment. In water and waste-water treatment processes, chlorine and chlorine compounds have been used as a main disinfectant throughout the world. Therefore, Caulobacter in the waters should be affected by chlorination of the waters. The objective of this study is to determine the effects of the disinfectants on Caulobacter cells and on the developmental processes of the cells. The Caulobacter swarmer cells were disinfected by chlorine at pH 7.0 minutes of the reaction with 2.0 mg/l of infected at pH 10.0. The swarmer cells treated with 2.0 or 4.0 mg/l of chlorine for 15 minutes lost their flagella and were observed by electron microscopy to be damaged on their cell surfaces, discharging some cellular materials. When the chlorinated swarmers and untreated control samples were recultivated in fresh PYE broth medium, the control swarmers multiplicated exponentially after one-hour lag phase, whereas the chlorinated swarmers extended the lag phase to about four hours. During the extended lag phase, the cells were proved by electron microscopy to be grown and be in predivisional step, but no swarmer cell was found. When the stalked cells were chlorinated, almost all the cells were observed to have their stalks broken and some cellular materials discharged. In those samples recultivated, many cells differentiated to possess an abnormally elongated stalk with several crossbands on it. This suggests that the chlorine-shocked Caulobacter cells can develope to abnormal morphology in water environments which they can survive and regrow in.

• Journal of Korea Soil Environment Society
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• v.5 no.3
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• pp.55-64
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• 2001

Many organochlorine pesticides are persistent in the environment and have a tendency to bioaccumulate significantly through food chains. Aquatic environments are particularly more affected because the pesticides applied to agriculture systems are eventually carried into water bodies, through surface runoff, rivers, and groundwater flow. The objective of this paper is to study the effect of the coexistence of a heavy metal on the solubility enhancement of the two representative organochlorine pesticides, lindane and dieldrin, by humic acids. The solubility enhancement of pesticides by humic acid in a single system was compared with that in a binary system. The extent of solubility enhancement of lindane by humic acids was constant. while that of dieldrin by humic acids increased. Also, the solubility enhancement of dieldrin by humic acid with Pb decreased than that by humic acid without Pb.

• Applied Microscopy
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• v.30 no.2
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• pp.233-240
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• 2000

Aspects of structural differentiation of the free -floating hydrophyte, Spirodela polyrhira, has been investigated. The hydrophyte exhibited highly reduced structures having only fronds, connective stalks, and roots as a mature plant. The fronds were major photosynthetic and vegetatively reproducing organ during the growth. Daughter fronds which developed early in the mother frond were also chlorenchymatous, but they remained within foliage sheaths of the mother frond before separation from connecting stalks. Although the stalks and roots originated from the same meristematic region of the frond, they exhibited the distinct polarity showing former lateral growth and latter axial growth. Air chambers were formed only in the fronds and roots. Cellular components were scattered throughout the diffuse cytoplasm in most of the actively growing stalk cells. Root cells protected by the root cap demonstrated relatively complex organization, showing dense cytoplasm with Golgi, rER, mitochondria, and chloroplasts in the cortical cells. Cells in the root cap were highly vacuolated within the peripheral cytoplasm. Such reduction and differentiation of the plant body in Spirodela polyrhiza most effectively contributes to the better adaptation of smaller plants to superficial aquatic environments, while also enabling the rapid growth.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.1
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• pp.57-68
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• 1998

Polycyclic aromatic hydrocarbons (PAMs) are ubiquitous contaminants in marine environments. PAMs enter estuarine and nearshore marine environment via several routes such as combustion of fossil fuels, domestic and industrial effluents and oil spills. PAHs have been the focus of numerous studies in the world because they are potentially carcinogenic, mutagenic, and teratogenic to aquatic organisms and humans from consuming contaminated food. However, one can hardly find any available data on PAM content in marine organisms in Korea. The present study was carried out in order to determine PAM content in oysters from the intertidal and subtidal zones of Chinhae Bay, which is located in near urban communities and an industrial complex, and the bay is considered to be a major repositories of PAHs. 16 PAHs were analyzed by High Performance Liquid Chromatography (HPLC) with uv/vis and fluorescence detectors in oysters: they are naphthalene (NPTHL), acenaphthylene (ANCPL), acenaphthylene (ACNPN), fluorene (FLURN), phenanthrene (PHEN), anthracene (ANTHR), fluoranthene (FLRTH), pyrene (PYR), benzo(a)anthracene (BaA), chrysene (CHRY), benzo(b)fluoranthene (BbF), benzo(k)fluoranthene (BkF), benzo(a)pyrene (BaP), dibenz(a,h)anthracene(DahA), benzo(g,h,i)peryne (BghiP) and indeno(1,2,3,-cd)pyrene (I123cdP). The PAM contents in oysters from the intertidal and subtidal zones of Chinhae Bay ranged from < 0.1 to 992.0 ug/kg (mean $69.8\pm9.8$ ug/kg).

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1993.06a
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• pp.4-5
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• 1993

Toxicity tests in our laboratory are conducted usually with mass-reared organisms. They are under the same environmentel conditions throughout seasons and are supplied at specific age. A total of 38 species of aquatic organisms are being reared. We have attempted to establish pruified strains or to select clones of various parthenogenic organisms. The merits or demerits of our culturing test organisms are discussed. The differences in the susceptibility among clones or strains of test organism are also discussed. For a single species test, algae, daphnia, fish are often used. However, we usually use early stages, but occasionally, adults fish are used for reproduction tests. As an another important aspect, the toxicity through food chains has been studied. In this study, we select a pair of species belonging different trophic levels. The differences between single species tests and multispecies tests will be discussed. Even a single species test intends to assess the effects of chemicals on ecosystem levels, however, this idea is not applicable to ecosystems. Single species tests with standard organisms and multispecies tests are contradictory in concept. One type of multispecles tests is indoor microcosms being composed of severel species artificially assembled, and another is composed of natural components (both indoor and outdoor). We have used three types of outdoor mesocosms using ponds and three types of artificial streams. The mesocosms is useful to not only to analyze the floral or faun61 changes but also to study the fate or behaviour of chemicals in naturd environments. Lastly, usefulness of the field observation or experiments or semi-field experiments will be discussed. This will enhance the exploitation of early warning systems utilizing indicator organisms or animal behaviour.aviour.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1005-1012
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• 2020

Acid mine drainage (AMD) has been a serious environmental issue that threatens soil and aquatic ecosystems. In this study, an acid-tolerant sulfate-reducing bacterium, strain S4, was isolated from the mud of an AMD storage pond in Vietnam via enrichment in anoxic mineral medium at pH 5. Comparative analyses of sequences of the 16S rRNA gene and dsrB gene involved in sulfate reduction revealed that the isolate belonged to the genus Desulfovibrio, and is most closely related to Desulfovibrio oxamicus (with 99% homology in 16S rDNA sequence and 98% homology in dsrB gene sequence). Denaturing gradient gel electrophoresis (DGGE) analyses of dsrB gene showed that strain S4 represented one of the two most abundant groups developed in the enrichment culture. Notably, strain S4 was capable of reducing sulfate in low pH environments (from 2 and above), and resistance to extremely high concentration of heavy metals (Fe 3,000 mg/l, Zn 100 mg/l, Cu 100 mg/l). In a batch incubation experiment in synthetic AMD with pH 3.5, strain S4 showed strong effects in facilitating growth of a neutrophilic, metal sensitive Desulfovibrio sp. strain SR4H, which was not capable of growing alone in such an environment. Thus, it is postulated that under extreme conditions such as an AMD environment, acid- and metal-tolerant sulfate-reducing bacteria (SRB)-like strain S4 would facilitate the growth of other widely distributed SRB by starting to reduce sulfate at low pH, thus increasing pH and lowering the metal concentration in the environment. Owing to such unique physiological characteristics, strain S4 shows great potential for application in sustainable remediation of AMD.

• Environmental Analysis Health and Toxicology
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• v.28
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• pp.16.1-16.8
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• 2013

Objectives Fish vitellogenin (VTG) is produced in the female liver during oogenesis through the estradiol cycle and produced in the male liver by endocrine disrupting chemicals (EDCs) such as alkylphenols. In this study, we propose that the VTG concentration in the pale chub could be detected using monoclonal antibodies and polyclonal antibodies against vitellin (Vn) in a VTG enzyme-linked immunosorbent assay (ELISA) system. Methods Monoclonal antibodies and polyclonal antibodies were produced using the Vn extracted from the matured ovum of the ovary. The VTG was extracted from the plasma of the male pale chub. The Vn and VTG were confirmed by measuring the molecular weight of their proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the specificity of the antibodies was checked through western blotting methods. The assay system was validated with respect to optimal assay concentrations, specificity, recovery, and intra- and inter-assay variations. Results The Vn consisted of two protein bands with apparent molecular weights of 64 and 37 kDa. The SDS-PAGE indicated protein weights of 146 and 77 kDa in the VTG. The assay range was 15.6 ng/mL to 2,000 ng/mL, and the value of the intra- and inter-assay variations were within 10.0% and 14.7%, respectively. The recovery rate was $99.5{\pm}5.5%$. Conclusions A sandwich ELISA was developed that could be used to qualify the VTG of pale chub in screening for EDCs. Pale chub is an ideal species for observing estrogen activity in the environment because of its extensive habitat and extensive food chain. The ELISA developed here would be more favorable than those for other species for determining the effect of long-term food chain accumulation of EDCs in aquatic environments.

• Environmental Engineering Research
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• v.14 no.4
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• pp.226-236
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• 2009

The performance of phytoremediation has proven effective in the removal of nutrients and metals from aqueous systems. However, little information is available regarding the behavior of pesticides and their removal pathways in aquatic environments involving plant-uptake. A detailed understanding of the kinetics of pesticide removal by plants and information on compound/plant partition coefficients can lead to an effective design of the phytoremediation process for anthropogenic pesticide reduction. It was determined that the reduction rates of four organophosphorus (OP) and two organochlorine (OC) pesticides (diazinon, fenitrothion, malathion, parathion, dieldrin, hexachlorobenzene [HCB]) could be simulated by first-order reaction kinetics. The magnitude of k was dependent on the pesticide species and found within the range of 0.409 - 0.580 $d^{-1}$. Analytical results obtained by mass balances suggested that differential chemical stability, including diversity of molecular structure, half-lives, and water solubility, would greatly influence the removal mechanisms and pathways of OPs and OCs in a phytoreactor (PR). In the case of OP pesticides, plant accumulation was an important pathway for the removal of fenitrothion and parathion from water, while pesticide sorption in suspended matter (SM) was an important pathway for removal of dieldrin and HCB. The magnitude of the pesticide migration factor (${\Large M}_p^{pesticide}$) is a good indication of determining the tendency of pesticide movement from below- to above-ground biomass. The uncertainties related to the different phenomena involved in the laboratory phyto-experiment are also discussed.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.471-487
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• 2013

This review paper was written to provide background information as well as future application for aquatic ecologists interested in using stable isotope. Stable isotope techniques has proved to be an extremely useful to elucidate a lot of environmental and ecological problems. Stable isotopes have been used as possible tracers to identify sources, to quantify relative inputs in a system. When utilized carefully, stable isotope tools provides apparent advantages for the scientists to find out the processes of material cycles in various environments and energy flows in natural ecosystems.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.331-337
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• 2008

Polycyclic aromatic hydrocarbons (PAHs) derived from leakage of fossil fuels and incomplete combustion of organic materials have been considered as harmful contaminants in environments. This study evaluated the effect of benzo[k]fluoranthene (BkF), one of the PAHs, using the multiple biomarkers and applied the integration model with those biomarker responses. After 10 days of the exposure at the measured concentrations of BkF (6, 25, and 45 ${\mu}g\;L^{-1}$), the changes of the four biomarkers, that is, 7-ethoxyresorufin-O-deethylase (EROD), DNA single-strand breaks (Comet), acetylcholinesterase (AChE) and vitellogenin (VTG) in the common carp (Cyprinus carpio) were observed. The standardized values of four biomarker responses were computed and integrated as star plots, representing Integrated Biomarker Respnse (IBR) values. DNA damage was induced in a dose-dependent manner, and increased significantly compared with that in the control. EROD and VTG levels were significantly elevated at low concentrations of BkF. On the other hand, AChE activities were not altered by BkF. IBR values increased as the exposure concentrations increased. Thus, the metabolic, endocrine and genetic changes of the biomarker responses in the common carp exposed to BkF should be considered in the case of the ecological risk assessment of the BkF in fish and it can be used as a biomonitoring tool in aquatic ecosystems. In addition, star plots can be used as a useful analysis tool in multibiomarker integration approach.