• Parasites, Hosts and Diseases
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• v.57 no.4
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• pp.439-444
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• 2019

Since Kudoa septempuntata was identified as a causative agent of food poisoning associated with raw olive flounder Paralichthys olivaceus, interest and concern regarding the parasite have increased. However, there have been no investigations or reports of other Kudoa species infecting the fish (except for K. paralichthys, which infects the brain) in Korea. We found cysts filled with myxospores of Kudoa species in muscles of cultured olive flounder specimens and identified these to the species level. Mature spores were quadrate, measuring $8.7{\pm}0.5{\mu}m$ in length, $9.2{\pm}0.4{\mu}m$ in thickness, and $12.9{\pm}0.6{\mu}m$ in width. The spores containing 4 polar capsules had a length of $2.1{\pm}0.2{\mu}m$ and a width of $1.8{\pm}0.3{\mu}m$. The partial 18S and 28S rDNA of isolates showed 99-100% similarities with K. ogawai. Using these morphological and molecular analyses, the species was identified as K. ogawai. This study is the first report of K. ogawai infection in cultured olive flounder in Korea.

• ALGAE
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• v.37 no.4
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• pp.281-291
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• 2022

Quantifying the abundance of Chattonella species is necessary to effectively manage the threats from ichthyotoxic raphidophytes, which can cause large-scale mortality of aquacultured fish in temperate waters. The identification and cell counting of Chattonella species have been conducted primarily on living cells without fixation by light microscopy because routine fixatives do not retain their morphological features. Species belonging to the Chattonella marina complex, including C. marina and C. marina var. ovata, had high genetic similarities and the lack of clear morphological delimitations between the species. To estimate the abundance of C. marina complex in marine plankton samples, we developed a protocol based on the droplet digital polymerase chain reaction (ddPCR) assay, with C. marina complex-specific primers targeting the internal transcribed spacer (ITS) region of the rDNA. Cell abundance of the C. marina complex can be determined using the ITS copy number per cell, ranging from 25 ± 1 for C. marina to 112 ± 7 for C. marina var. ovata. There were no significant differences in ITS copies estimated by the ddPCR assay between environmental DNA samples from various localities spiked with the same number of cells of culture strains. This approach can be employed to improve the monitoring efficiency of various marine protists and to support the implementation of management for harmful algal blooms, which are difficult to analyze using microscopy alone.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.186-190
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• 2007

The species composition and the biomass of intertidal microphytobenthos (MPB) were investigated at four sites in the Nakdong Estuary from Feb. to Dec. 2006. The chlorophyll (chl) ${\alpha}$ concentration showed a positive correlation with MPB abundance, and depth profiles showed similar patterns: high at the surface, rapidly decreasing within 4 cm from the surface, and slowly decreasing thereafter. A MANOVA analysis revealed that the chl ${\alpha}$ concentration varied significantly not only with depth, month, and site, but also with combinations of these factors. Among the four investigated sites, site D (Baekhabdeung) showed a seasonal biomass variation trend distinct from those of the other sites: higher in summer, decreased in autumn and with sustained low values until winter. As indicated, the other sites contrastingly showed low biomasses in summer, after which the biomasses continuously increased, with some variation among the sites. A cluster analysis of species composition indicated that sites near to each other and with similar sediment structures had closer similarities in the same seasons. The species of genus Amphora and Navicula were dominant at the four sites throughout the study period.

• Journal of Species Research
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• v.13 no.3
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• pp.332-339
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• 2024

The filamentous freshwater red alga Compsopogon caeruleus(Compsopogonophyceae, Compsopogonaceae, Rhodophyta) occurs in tropical and subtropical regions of worldwide. This species has been reported from Asia, America, Africa, Europe and Oceania, and the worldwide distribution of Compsopogon caeruleus is in variable water habitats. Several morphospecies of the genus Compsopogon had been recorded, but recent molecular phylogenetic analyses with worldwide sampling identified a monospecific genus, C. caeruleus. In the present study, we first report a freshwater red alga Compsopogon caeruleus from Korea. We identified Compsopogon caeruleus in an urban river in Yongin City, and analyzed its morphological and genetic characteristics. Nuclear 18S rDNA, plastidal rbcL gene and mitochondrial cox1 gene sequences isolated from Korean Compsopogon caeruleus showed high sequences similarity with Compsopogon caeruleus from worldwide (98.6-100% (18S rDNA), 99-100% (rbcL) and 97.7-100% (cox1)). These sequences similarities support the identification of a red alga found in Korea as Compsopogon caeruleus. This new geographical report provides the useful information for understanding the distribution and habitat range of Compsopogon caeruleus especially concerning urban freshwater environments.

• Journal of Species Research
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• v.9 no.4
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• pp.346-361
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• 2020

In the project of a comprehensive investigation of indigenous prokaryotic species in Korea, a total of 39 bacterial strains phylogenetically belonging to the classes Betaproteobacteria and Gammaproteobacteria were isolated from various environmental sources such as soil, cultivated soil, sludge, seawater, marine sediment, algae, human, tree, moss, tidal flat, beach sand and lagoon. Phylogenetic analysis based on 16S rRNA gene sequences revealed that 39 strains showed the high sequence similarities (≥98.7%) to the closest type strains and formed robust phylogenetic clades with closely related species in the classes Betaproteobacteria and Gammaproteobacteria. In the present study, we report 14 species of 9 genera of four families of two orders in the class Betaproteobacteria and 25 species of 21 genera of 15 families of eight orders in the class Gammaproteobacteria, which have not been reported in Korea. Morphological, biochemical, and physiological characteristics, isolation sources, and NIBR deposit numbers are described in the species descriptions.

• Ocean Science Journal
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• v.43 no.2
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• pp.101-106
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• 2008

A single specimen of Albula leptocephalus (55.7 mm SL) was collected from the southern coastal waters of Korea using an aquatic lamp. It is characterized by having a ribbon-like body with a small head and a well-forked caudal fin. Although the general appearance was similar to the leptocephalus of A. vulpes including myomere counts and fin ray counts, the melanophore deposition was different from that of A. vulpes. This leptocephalus specimen was confirmed with A. forsteri using the cytochrome b mtDNA (Cytb) analysis. The genetic distance of Cytb between the present leptocephalus and A. forsteri is 0.006-0.038, which falls into the cutoff point separating Albula species into eight deep lineages including the four valid species. Its genetic characteristic have more similarities to those of Fiji than those of Hawaii and the Northern territory of Australia.

• Korean Journal of Microbiology
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• v.10 no.4
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• pp.155-166
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• 1972

With respect to a bacterium isolated some of the similarities and differences previously indicated between Thiobacillus thiooxidans and Thiobacillus concretivorus wee confirmed and the bacteria also provided considerable diferences compared to the two species in some repects. Severe precipitation of sulfur occurred in colonies and in liquid media of the organism isolated. The organism isolated utilized nitrate and asparagine as well as ammonium sulfate as a sole nitrogen source and grew well without being nearly inhibited by citrate and malate. This organism also showed the resistance to heats and external physical stimulations. Owing to some characters decribed above and the reports proposed, the organism isolated could be concluded to be Thiobacillus concretivorus and it was suggested that Thiobacillus concretivorus might be an apparently different species from Thiobacillus thiooxidans.

• BMB Reports
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• v.39 no.3
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• pp.292-296
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• 2006

DNA sequencing has resulted in an abundance of data on DNA sequences for various species. Hence, the characterization and comparison of sequences become more important but still difficult tasks. In this paper, we first give a 2-D ladderlike graphical representation for the characteristic sequences of a DNA sequence, and then construct a 3-component vector, in which the normalized ALE-indices extracted from such three 2-D graphs via D/D matrices are individual components, to characterize the DNA sequence. The examination of similarities/dissimilarities among sequences of the $\beta$-globin genes of different species illustrates the utility of the approach.

• Atmosphere
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• v.20 no.3
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• pp.367-377
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• 2010

Variation of tracer distribution during the vortex-breakup period in the Antarctic region was observed by the data from the Improved Limb Atmospheric Spectrometer (ILAS) and ILAS-II. All four trace species including methane, nitrous oxide, ozone, and water vapor show similar patterns of vertical gradient in spite of different structures of zonal mean mixing ratio. Timings of vortex breakup on each level are estimated by two different methods, and they are compared with zonal standard deviations following the latitude circle of each trace species. Although the tracers have different chemical life times and sink/source, the zonal standard deviation patterns show remarkable similarities. The zonal standard deviation shown here to measure the zonal asymmetry of tracer distribution is believed to diagnose the timing of the Antarctic polar-vortex breakup reasonably well.

• Mycobiology
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• v.32 no.4
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• pp.179-185
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• 2004

Arbuscular mycorrhizal fungi were observed in Botrychium ternatum native in Korea. The partial small subunit(SSU) of ribosomal DNA gene from the fern roots was amplified with primers AM1/NS31. Nucleotides sequence analysis of the clones revealed that two fragments were close to Glomus proliferum and G. sinuosum. The other three DNA fragments were close to those of G. proliferum with the relatively low similarities($92{\sim}95%$) and speculated to be originated from three different species of Glomus(GLA006, GLA016, and GLA032). Five different nucleotide sequences close to three AM fungal species were found in the roots of B. ternatum native in Korea.