• Journal of Species Research
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• v.11 no.2
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• pp.108-116
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• 2022

During a field survey to report unrecorded Korean ciliates, we collected five anaerobic ciliate species in two samples from freshwater and marine environments. These species belong to the classes Armophorea and Plagiopylea. The morphology of these species was studied based on live observations, protargol impregnation, and scanning electron microscope. Brachonella contorta is characterized by a size of 80-100×40-60 ㎛ in vivo, a bullet-shaped body, and about 60 oral polykinetids making 360° spiral around long axis. Brachonella pulchra is characterized by a size of 80-110×50-70 ㎛ in vivo and adoral zone composed of about 40 oral polykinetids with minimal spiralization. Metopus setosus is characterized by a size of 45-70×20-30 ㎛ in vivo, about 22 ciliary rows, very long caudal cilia, and 20 oral polykinetids. Plagiopyla nasuta is a freshwater species characterized by a size of 80-120×50-60 ㎛ in vivo, striated band present, straight extrusomes, and about 70 somatic ciliary rows. The marine Plagiopyla frontata is characterized by a size of 80-120×40-60 ㎛ in vivo, an oval to ellipsoid body shape, 50-60 somatic ciliary rows, and curved extrusomes.

• Mycobiology
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• v.51 no.5
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• pp.320-332
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• 2023

Talaromyces is a genus within the phylum Ascomycota (class Eurotiomycetes, order Eurotiales, family Trichocomaceae). Many species in this genus are known to produce diverse secondary metabolites with great potential for agricultural, medical, and pharmaceutical applications. During a survey on fungal diversity in the genus Talaromyces in Korea, six strains were isolated from soil, indoor air, and freshwater environments. Based on morphological, physiological, and multi-locus (ITS, BenA, CaM, and RPB2) phylogenetic analyses, we identified five previously unrecorded species in Korea (T. brevis, T. fusiformis, T. muroii, T. ruber, and T. soli) and a new species (T. echinulatus sp. nov.) belonging to section Talaromyces. Herein, detailed descriptions, illustrations, and phylogenetic tree are provided.

• 한국해양학회지
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• v.30 no.4
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• pp.320-331
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• 1995

The closely spaced cores were analyzed to find detailed reconstruction of paleoenvironments and sealable changes along the Delaware Bay coast. Three areas, Kitts Hummock Beach mars, the St. Jones River marsh, and Bowers marsh near the St. Jones River's mouth, were chosen because these areas are compose of their own geomorphic characteristics and sea-level history. since significance of the stratigraphic correlations was to determine sedimentary fancies and paleoenvironments, multidisciplinary methods such as lithological description, grain-size analysis, organic/inorganic content, water content, mineral composition, botanical analysis, micropaleontological analysis, and /SUP 14/C datings were performed. Five major divisions of marsh environments were recognized in the stratigraphic sections: freshwater marsh, initialfreshwater marsh, slightly brackish marsh, brackish marsh, and salt marsh. Most of the lower part in the stratigraphic sections show freshwater marsh. On the top of this, either brackish marsh or tidal flat/tidal stream was recorded. The pro-Holocene sediments consist of sand, mud, and sandy mud, The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene sediments consist of sand, mud, and sandy mud. The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene surface within short distances permitted the concurrent development of variable environments such as freshwater marsh, brackish marsh or salt marsh at similar elevations. The freshwater marsh in this case was formed in the areas of isolation, so saline-water cannot encroach upon these areas. This complex development of paleoenvironments leads to a difficulty in stratigraphic correlation and interpretation of local relative sea-level changes. The deposition of subsurface sediments was affected by sediment supply, compaction, fluvial activity, biological competition, local tectonics and isostacy, climate and local relative sea-level changes. It was interpreted that the positions in the changes from freshwater environments to brackish environments or ice versa are the turning points of transgressions and regressions. Therefore, multiple transgressions and regressions were identified in the stratigraphic sections of the study area.

• Ocean and Polar Research
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• v.28 no.2
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• pp.107-117
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• 2006

Freshwater algal studies in North polar environments are relatively few. This study presented the algal-flora, -biomass and genetic features of dominant cells collected from temporary ponds around the Polar Research Station (PRS), Norway. Water samples were collected from 4 stations around PRS, and analyzed for their environmental and biological variables. Water temperature, salinity and conductivity ranged from 5 to $10^{\circ}C$, 0.1 to $0.3%_{\circ}$ and 0.21 to $0.36{\mu}S/cm$, respectively. Chlorophyll a concentration ranged from 1.8 to $11.1{\mu}g/l$, and that of the size-fractionated cells was recorded from 0.7 to $1.1{\mu}g/l$ in picoplankton 0.3 to $6.5{\mu}g/l$ in nanoplankton, and 0.4 to $3.9{\mu}g/l$ in microplankton respectively. Algal flora in the present study was recorded as 10 genera, in which Chlamydomonas, particularly, was dominant in all studied sites. By comparison of Chlamydomonas 18S rDNA sequences, including two isolates from PRS, they formed a distinct clade against others: sequence similarity was significantly low (<97.2%) with C. noctigama, being the highest score by BLAST search in GenBank. This study was valuable for basic knowledge regarding the freshwater algae around PRS and their genetic information.

• The Korean Journal of Mycology
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• v.51 no.4
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• pp.349-359
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• 2023

Freshwater ecosystems are significant habitats of fungi including yeasts. This study aimed to isolate and characterize wild yeasts from freshwater environments in Korea. The yeast isolates were identified by using the D1/D2 domains of the 26S rDNA regions. We identified four strains, Candida viswanathii (NNIBRFG39781), Curvibasidium cygneicollum (NNIBRFG49003), Oberwinklerozyma silvestris (NNIBRFG39803) and Vishniacozyma foliicola (NNIBRFG6120). These yeasts had not previously been recorded in Korea. We investigated the morphological and cultural characteristics of these yeasts. All of them grew on YPD, PD and YM media. Candida viswanathii (NNIBRFG39781), O. silvestris (NNIBRFG39803) and V. foliicola (NNIBRFG6120) grew in YPD medium containing glucose and in pH range of 4-8. Curvibasidium cygneicollum (NNIBRFG49003) grew well low temperature compared to others and slowly.

• 한국생태학회:학술대회논문집
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• 1999.05a
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• pp.43-54
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• 1999

1. Hanoi city was built up on the wetland landscape of the Red River delta therefore it has a network of many lakes and rivers. 2. The aquatic biodiversity (Macrophytes, Invertebrates, Fishes, Vertebrates) of the 6 main lakes (Ho Tay, Hoan Kiem, Bay Mau, Giang Vo, Dong Da, Thanh Nhan) are rich and diverse. It represents the patterns of Red River delta one's. Many rare and endangered species are found in these lakes Particularly a giant freshwater turtle species in Hoan Kiem lake. 3. All of these lakes are more or less polluted. Their environments are seriously degrading both in water quality and aquatic biodiversity. 4. Based on socio-economical and cultural role of these lakes of Hanoi city, it is very necessary to preserve and to restore their environments and aquatic biodiversity: water Pollution control, landscape planning, making roads around the lakes and erosion control for their banks, legislation measures, rational exploitation of aquatic biodiversity, restoration the artificial wetlands with macrophytes.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.5
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• pp.77-88
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• 2022

This study aims to understand the relationship between the distribution of fish species in the two water ecosystems and the habitat factors according to the survey period targeting Gwanggyo Lake Park in the city. There are studies on the appearance and distribution of species by applying eDNA to freshwater ecosystems. However, in the domestic, streams are the target, and studies on the relationship between species distribution and habitat environment in two water environments are lacking. We conducted to analyze the species list and relationship with habitat factors using eDNA research in May and October at 21 points in Gwanggyo Lake Park, Suwon City, which were connected to lakes and streams. As a result, there was no species difference in the water environment according to the survey period. However, the total number of reads during the spawning season(May) was 3,126,482, which was more than double that after the spawning season(October). Tolerant species appeared in Woncheon Lake with a slow or stagnant flow, but there was no significant correlation between species and habitat factors depending on the survey period. On the other hand, intermediate and sensitive species appeared in the Woncheon stream with high flow. There was a significant correlation between the low temperature during the spawning season and the high dissolved oxygen content after the spawning season(P<0.001, Tem.: 20.7±2.6℃, DO: 8.6±1.7). It is expected that environmental DNA will be used to survey species and suggest monitoring methods according to the survey period.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.219-228
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• 1990

A kanamycin resistance($Km^r$) gene was studied for its transfer in natural freshwater environments by using the natural bacterial isolate(M1) of DK1 and the DKC601 strain, $Km^r$ plasmid of which was genetically engineered from the NI strain. The transfer frequency ofthe $Km^r$ gene and rearrangement of the $Km^r$ plasmid were compared between the gnetically engineered microorganism(GEM) and the NI parental strain by conjugation with the same recipient strain. The transfer frequency of the $Km^r$ gene was about $9.1\times 10^{-12}-1.8\times 10^{-11}$ in both the GEM and NI strains at 5 to $10^{\circ}C$, but the frequency of the NI was about 10 times higher than that of the GEM at 20 to $30^{\circ}C$. The $Km^r$ plasmid in the transconjugants obtained by conjugation of the NI with the MY1 strain as a ricipient showed alot of rearrangement, but the $Km^r$ plasmid transferred from the GEM was stable without alteration of its size. When the MT2 strain was used as a recipient, however, such a rearrangement of the $Km^r$ plamid was observed in the transconjugants obtained from the GEM as well as the NI strain. In those transconjugants obtained from different mating pairs and water environments, the plasmid were appeared to decrease in their number as the period of conjugation time was prolonged, but only the $Km^r$ plasmid transferred from the GEM kept having its size of 52kb. Therefore, the $Km^r$ gene was transferred at the same rate from the GEM and NI strains in natural freshwater environment, but the gene of the GEM strain was more stable than the NIduring conjugation and the $Km^r$ plasmid was rearranged by changing the recipient strain for conjugation in any water environments.

• Journal of Microbiology
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• v.43 no.2
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• pp.144-151
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• 2005

During the past ten years, Archaea have been recognized as a widespread and significant component of marine picoplankton assemblages. More recently, the presence of novel archaeal phylogenetic lineages has been discovered in coastal marine environments, freshwater lakes, polar seas, and deep-sea hydrothermal vents. Therefore, we conducted an investigation into the archaeal community existing in tidal flat sediment collected from Ganghwa Island, Korea. Phylogenetic analysis of archaeal 16S rDNA amplified directly from tidal flat sediment DNA revealed the presence of two major lineages, belonging to the Crenarchaeota ($53.9\%$) and Euryarchaeota ($46.1\%$) phyla. A total of 102 clones were then sequenced and analyzed by comprehensive phylogenetic analysis. The sequences determined in our samples were found to be closely related to the sequences of clones which had been previously obtained from a variety of marine environments. Archaeal clones exhibited higher similarities ($83.25 - 100\%$) to sequences..from other environments in the public database than did those ($75.22 - 98.46\%$) of previously reported bacterial clones obtained from tidal flat sediment. The results of our study suggest that the archaeal community in tidal flat sediment is remarkably diverse.

• Environmental Analysis Health and Toxicology
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• v.24 no.4
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• pp.311-320
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• 2009

The short term (24-hr) and long term (21 days) effects of copper, cadmium, fenbendazole and sulfathiazole on the survival of the Korean fairy shrimp Branchinella kugenumaensis were evaluated. The 24-hr median lethal concentrations ($LC_{50}$) of copper, cadmium, fenbendazole, and sulfathiazole were 39, 512, 182, and 31,818 ${\mu}g/L$, respectively. The toxicity of copper is highest among 4 chemicals used in this study, while sulfathazole the lowest. After the long term (21 days) exposure experiment, the $LC_{50}$ copper, cadmium, fenbendazole, and sulfathiazole were 1.12, 2.1, 0.1, 6.6 ${\mu}g/L$, respectively. The long term effects of antibiotics were highly enhanced while the short-term effects were not strong. The sensitivities of B. kugenumaensis to copper and cadmium were higher than or comparable to those of other freshwater branchiopods (Streptocephalus spp., Thamnocephalus sp.), and far higher than the marine species (Artemia sp.). There were significant effects on the survival of B. kugenumaensis after long term exposure to relatively lower concentrations of copper, cadmium, fenbendazole and sulfathiazole. Therefore, B. kugenumaensis seems quite a good candidate species for the ecotoxicological assessments of freshwater environments.