Publications by authors named "Joong Ki Choi"

Six isolates of mineral-enveloped Strombidinopsis minima-like species were collected from the coastal waters across several regions in Korea. Morphological observations and molecular analyses were performed. The ribosomal DNA sequences (including small subunit ribosomal DNA, internal transcriber spacer 1-5.

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We characterized six tintinnid ciliates from Antarctic waters using molecular markers and morphological traits: Amphorellopsis quinquealata, Codonellopsis gaussi, Cymatocylis convallaria, Cy. calyciformis, Cy. drygalskii, and Laackmanniella prolongata.

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Despite recent advance in mass sequencing technologies such as pyrosequencing, assessment of culture-independent microbial eukaryote community structures using universal primers remains very difficult due to the tremendous richness and complexity of organisms in these communities. Use of a specific PCR marker targeting a particular group would provide enhanced sensitivity and more in-depth evaluation of microbial eukaryote communities compared to what can be achieved with universal primers. We discovered that many phylum- or group-specific single-nucleotide polymorphisms (SNPs) exist in small subunit ribosomal RNA (SSU rRNA) genes from diverse eukaryote groups.

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The effect of Ag decoration on the gas sensing characteristics of SnO(2) nanowire (NW) networks was investigated. The Ag layers with thicknesses of 5-50 nm were uniformly coated on the surface of SnO(2) NWs via e-beam evaporation, which were converted into isolated or continuous configurations of Ag islands by heat treatment at 450 °C for 2 h. The SnO(2) NWs decorated by isolated Ag nano-islands displayed a 3.

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The identification of Favella ehrenbergii, a marine planktonic ciliate, has largely been based on its lorica features. This approach is potentially problematic given the polymorphic lorica during this organism's life cycle. We isolated a population of F.

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A choreotrich ciliate collected in waters off Geoje Island, on the eastern coast of the South Sea of the southern coastal water of Korea was morphologically and biometrically investigated through observations of permanent preparations after protargol impregnations. Morphological data and ciliary patterns indicated that the ciliate should be identified as Strombidinopsis acuminata based on the number of somatic kineties. The vertical distribution of the population abundance was also examined in relation to environmental conditions: higher abundances occurred in surface water with higher temperature (22-23 degrees C), lower salinity (32 psu), and higher concentration (ca 10 microg/L) of chlorophyll a.

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The purpose of this research was to analyze the underlying mechanisms and contributing factors related to the seasonal dynamic of harmful algal blooms in a shallow eutrophic pond, Bangladesh during September 2005-July 2006. Two conspicuous events were noted simultaneously throughout the study period: high concentration of phosphate-phosphorus (>3.03; SD 1.

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The ciliate community structure and seasonal dynamics in a solar saltern of the Yellow Sea were studied based on 4 sampling dates and 8 stations with salinities from 27.7 per thousand to 311.0 per thousand.

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Structural and functional parameters of periphytic ciliate communities were studied for monitoring water quality in Korean coastal waters during April 2007. The PFES (polyurethane foam enveloped slide) system, a modified glass slide method, was used to analyze periphytic ciliate colonization in marine ecosystems. A total of 27 ciliate species were identified using living observation and silver impregnation method with this system.

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A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293 per thousand) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing.

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The morphology and infraciliature of a new ciliate, Kiitricha minuta n. sp., isolated from the Yellow Sea, were investigated using live observation and protargol impregnation.

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The morphology and infraciliature of two stichotrichid ciliates, Gastrostyla pulchra(Perejaslawzewa 1886) Kahl, 1932 and Hemigastrostyla enigmatica(Dragesco and Dragesco-Kernéis 1986) Song & Wilbert, 1997, collected from marine and brackish sediments, were investigated by using living observations and protargol impregnations. Both 18S and 28S rRNA genes of these two species were sequenced. The 18S rDNA show high similarities (98.

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Ciliates are highly diverse in the benthos where there are rare species to be unrevealed and described. By isolating species during successive and diversified cultivations, we discovered several new and interesting taxa from the top layer sediment of a muddy site in the Ganghwa tidal flat. These include three new species Spirodysteria ganghwaensis n.

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The morphology and infraciliature of a new ciliate, Tunicothrix rostrata n. g., n.

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Two marine urostylid ciliates, Holosticha hamulata n. sp. and Holosticha heterofoissneri Hu and Song, 2001, were investigated using live observation and protargol impregnation.

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Screening experiments were conducted in order to find promising synthetic surfactants for harmful algal blooms (HABs) mitigation. The chemically synthesized surfactant cocamidopropyl betaine (CAPB) showed characteristics of relatively high inhibition efficiency, high biodegradability and low cost. The motility inhibition ratios of 10 mg/L CAPB on Cochlodinium polykrikoides and Alexandrium tamarense were about 60% after 5 min.

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The inhibition effect of sophorolipid and removal efficiency of loess on Cochlodinium polykrikoides and Alexandrium tamarense was investigated separately in the laboratory. Based on this, the combination of sophorolipid and loess for harmful algal bloom mitigation was proposed. Algal sedimentation tests in the laboratory and in the field revealed that the combination of sophorolipid and loess showed synergistic effects both on the removal efficiencies and on the mitigation cost.

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The morphology and infraciliature of a new hypotrichous ciliate, Euplotidium smalli n. sp., isolated from eutrophic coastal water in Korea, were observed in living cells and investigated using the protargol impregnation technique.

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Structural and functional parameters of protozoan communities were assessed as indicators of water quality in Korean coastal waters in the summer of 2000. A modified polyurethane foam unit (PFU) method, named the bottled PFU (BPFU) system, was used in order to carry out the bioassessment. Both parameters suggested that biomonitoring using the BPFU system was more effective than the conventional PFU method in offshore areas.

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