• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.234-242
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• 2014

In this study, gametotoxicity and embryotoxicity experiments using Hemicentrotus pulcherrimus were carried out to investigate the ecotoxicological effects of bisphenol A (BPA). We examined the effects of BPA on fertilization and normal embryogenesis at various concentrations (0, 300, 500, 800, 1000, and 1500 ppb). The results demonstrated that the fertilization rates were not changed. The normal embryogenesis rates were gradually decreased in a dose-dependent manner, and were significantly lowered following 800 ppb BPA treatment ($EC_{50}$=1056.1 ppb, 95% Cl=981.8~1163.9 ppb). The observed effective concentration and the lowest observed effective concentration of the normal embryogenesis rate were 500 ppb and 800 ppb, respectively. The embryos showed retarded development at each tested concentration, indicating the fact the embryonic development was delayed due to the increasing concentrations of BPA. Furthermore, we examined the expression of glutathione S-transferase (GST) mRNA at various concentrations of BPA in H. pulcherrimus. Interestingly, it was found that the expression level of GST mRNA was significantly increased in the experimental group exposed to BPA. Based on these results, we suggested that BPA at greater than 800 ppb has a toxic effect during the early embryonic stages of H. pulcherrimus, and GST mRNA may be used as a biomarker for risk assessment of BPA contamination.

• Korean Journal of Environment and Ecology
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• v.31 no.5
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• pp.461-471
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• 2017

Population genetic studies of 10 groups of Iksookimia pacifica were conducted to investigate the genetic diversity and population genetic structure across its known range in South Korea. Population DNA sequences of one mitochondrial gene (mtCOI) and three nuclear genes (IRBP, EGR2B, RAG1) were examined in samples collected from ten streams that flow into the East Sea. Both mitochondrial and nuclear sequences exhibited significant differentiation among populations except a few cases. The Bayesian analysis of the multi-locus genotypes inferred from the DNA sequences of nuclear genes clustered the individual fish largely into two geographical groups: a northern group (from Baebong stream to Cheonjin stream) and a southern group (Yangyangnamdae stream to Gangneungnamdae stream). Given that the streams flowing into the East Sea are geographically isolated water systems, such separation of genotypes can be interpreted by the geographical separation of common ancestors into north and south that had colonized South Korea. Since the initial geographical separation of the ancestral population by north and south, the ancestral groups seem to have experienced further differentiation into the current genetic clusters through the physical isolation of streams by the East Sea in each region. It is notable that many individuals in the Jasan stream formed a genetic cluster with those of Yangyangnamdae and Gangneungnamdae streams which are distant from each other. In addition, mitochondrial gene showed low genetic differentiation between some neighboring populations and very low level of genetic diversity in several populations. The present population genetic study will provide valuable information for the conservation and management of the Korean endemic fish species, I. paicifica.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.507-512
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• 2005

This research focuses on the development and application of a method for the detection of m-toluate in soils using a genetically engineered bioluminescent bacteria, Pseudomonas putida mt-2 KG1206. KG1206 produces light by direct (m-toluate and benzoate) and indirect (toluene analogs) inducers. For detection of m-toluate in soil system, 9.9 mL strain was amended with 0.1 mL soil ethanol extractant. A high correlation ($r^2>0.97$) was observed between bioluminescence and m-toluate concentration. The unknown concentrations of m-toluate in soil samples were pre-determined using a method developed based on bioluminescence activity of strain with extracted inducers. Values between by LC analysis and bioluminescence activity show moderate statistical results. These results demonstrate the feasibility of recombinant bioluminescent microorganism, engineered to generate a quantifiable bioluminescence signal in response to specific pollutants, may serve as combined sensing and reporting tools in environmental monitoring.

• Journal of Life Science
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• v.23 no.2
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• pp.182-189
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• 2013

Halophytes are unique land plants that are capable of thriving in a high-salt environment. They are attracting public attention due to their ability to synthesize bioactive substances such as UV protectants or antioxidizing agents. To achieve unaffected growth under high salinity, halophytes may take advantage of the activities of cell growth factors such as expansins. Expansins are well-known cell wall proteins that are responsible for cell enlargement. They loosen cell walls, thereby contributing to actual plant growth. This study aimed to identify positive roles of expansins in the growth of halophytes. Three expansin cDNA clones were isolated from seedlings of Suaeda japonica. Comparing the deduced amino acid sequences of the expansin genes of S. japonica with those of other plant species suggested that the cDNA clones isolated from S. japonica belong to the EXPA (${\alpha}$-expansin) gene family. A phylogenetic tree based on the deduced amino acid sequences revealed that the expansins of S. japonica share a close evolutionary relationship with those of strawberry (Fragaria ananassa) and jujube (Ziziphus jujuba), both of which are woody dicots. SjEXPAs did not show any remarkable change in the gene expression level in different NaCl concentrations, providing a clue to the unaffected seedling growth of S. japonica in a high-salt environment. In conclusion, the present study presents the first report of expansin genes from halophytes and suggests a putative role for these genes in plant growth under high salinity.

• Korean Journal of Environment and Ecology
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• v.35 no.5
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• pp.503-524
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• 2021

A largemouth bass (Micropterus salmoides) is an ecosystem disturbance fish species at the highest rank in the aquatic ecosystem, causing a serious imbalance in freshwater ecosystems. Although various attempts have been made to eradicate and control largemouth bass, no effective measures were found. Therefore, it is necessary to find an approach to maximize the effective population reduction based on the unique characteristics of largemouth bass. This study used the transcriptome analysis to derive 182,887 unigene contigs and select 12 types of final target sequences for applying the CRISPR/Cas9 system in the genes of IZUMO1 and Zona pellucida sperm-binding protein, which are proteins involved in sperm-egg recognition. After synthesizing 12 types of sgRNA capable of recognizing each target sequence, 12 types of Cas9-sgRNA ribonucleoprotein (RNP) complexes to be used in subsequent studies were prepared. This study searched the protein-coding gene of sperm-egg through the Next Generation Sequencing (NGS) and edited genes through the CRISPR/Cas9 system to induce infertile individuals that produced reproductive cells but could not form fertilized eggs. Through such a series of processes, it successfully established a composition development process for largemouth bass. It is judged that this study contributed to securing the valuable basic data for follow-up studies to verify its effect for the management of ecological disturbances without affecting the habitat of other endemic species in the same water system with the largemouth bass.

• Korean Journal of Microbiology
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• v.55 no.1
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• pp.69-73
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• 2019

During screening of microbes for compounds having cosmetic benefits, we isolated Marinobacter salarius HL2708#2 from lava seawater on Jeju Island, Republic of Korea. The complete genome sequence was determined. Strain HL27080#2 features a circular chromosome of 4,304,603 bp with 57.21% G+C content and a 244,163 bp plasmid with 53.14% G+C. There were 4,180 protein coding sequences identified, along with 49 transfer RNA and 18 ribosomal RNA noncoding genes. The genome harbored genes for the utilization of alcohol, maltose/starch, and monosaccharide as sole carbon sources. Genes responsible for halophilic characteristics and heavy metal resistance could be annotated, as well as aromatic and alkane hydrocarbons. Contrary to the prior report that M. salarius is negative for nitrate and nitrite reduction, nitrate/nitrite reductase along with nitrate/nitrate transporters and nitronate monooxygenase were evident, suggesting that strain HL2708#2 may be able to denitrify extracellular nitroalkenes to ammonia.

• Journal of Life Science
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• v.31 no.1
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• pp.28-36
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• 2021

Edwardsiella piscicida is a significant cause of hemorrhagic septicemia in fish and gastrointestinal infections in humans. Survival bacteria require specialized mechanisms to adapt to environmental fluctuations. Hence, to understand the mechanism through which E. piscicida senses and responds to environmental osmolarity changes, we determined the protein expression profile and physiological properties under various salinity conditions in this study. The OmpR protein is a part of the Env-ZOmpR two-component system that has been implicated in sensing salt stress in bacteria. However, the physiological role played by this protein in E. piscicida remains to be elucidated. Therefore, in this work, the function of the OmpR protein in response to salt stress was investigated. Phenotypic analysis revealed that, in the mutant, three of the biochemical phenotypes were different from the wild type, including, citrate utilization, hydrogen sulfide, and indole production. Introduction of the plasmid containing the entire ompR gene to the mutant strain returned it to its parental phenotype. The retarded growth rate also partially recovered. Furthermore, in our studies, OmpR was not found to be related to cell motility. Taken together, our results from the mutational analysis, the growth assay, MALDI-TOF MS, qRT-PCR, and the phenotype studies suggest that the OmpR of E. piscicida is implicated in osmoregulation, growth, expression of porins (ETAE_1826), virulence-related genes (EseC, EseD and EvpC), and certain genes of unknown function (ETAE_1540 and ETAE_2706).

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.99-108
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• 2023

Several challenges arise in DNA extraction and gene amplification for airborne fungal metagenome analysis from a particulate matter (PM) samples. In this study, various conditions were tested to optimize the DNA extraction method from PM samples and polymerase chain reaction (PCR) conditions with primer set and annealing temperature. As a result of comparative evaluation of DNA extraction under various conditions, chemical cell lysis using buffer and proteinase K for 20 minutes and bead beating treatment were followed by using a commercial DNA extraction kit to efficiently extract DNA from the PM filter samples. To optimize the PCR conditions, PCR was performed using 10 primer sets for amplifying the ITS2 gene region. The concentration of the PCR amplicon was relatively high when the annealing temperature was 58℃ with the ITS3tagmix3/ITS4 primer set. Even under these conditions, when the concentration of the PCR product was low, nested PCR was performed using the primary PCR amplicon as the template DNA to amplify the ITS2 gene at a satisfactory concentration. Using the methods optimized in this study, DNA extraction and PCR were performed on 15 filter samples that collected PM2.5 in Seoul, and the ITS2 gene was successfully amplified in all samples. The optimized methods can be used for research on analyzing and interpreting the fungal metagenome of atmospheric PM samples.

• Journal of the Korean Applied Science and Technology
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• v.40 no.4
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• pp.881-889
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• 2023

The genus Hymenobacter, type genus of the family Hymenobacteraceae and a member of the phylum Bacteroidota includes gram-negative and red-pigmented rods. Those bacteria have been isolated from various environments of the earth. I isolated a red-pigmented, gram-negative rod from a pond in the campus of the Changwon University, Changwon, Kyeongnam and designated this bacterium as strain B2. Strain B2 was further analyzed phylogenetically and biochemically, and concluded as a member of genus Hymenobacter. BLAST search of the 16S rRNA gene sequence of strain B2 showed its homology lower than 98.7% with those sequences of the other bacteria whose 16S rRNA gene sequences have been reported. Fatty acid composition of the strain B2 was analyzed and its major fatty acids are summed feature 3(C_16:1 ω7c and/or C_16:1 ω6c, 22.8%), iso-C_15:0 (16.2%), anteiso-C_15:0(12.9%), C_16:1ω5c(12.4%) and summed feature 4 (iso-C_17:1 I/anteiso-C_17:1)(9.5%) showing significant differences in fatty acid compositions between strain B2 and the other known Hymenobacter species. DNA sequence of 16S rRNA gene of strain B2 was deposited in genbank under accession number OQ318247.

• Journal of Life Science
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• v.28 no.9
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• pp.1030-1041
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• 2018

Abiotic stresses limit the growth and productivity of plants. Cellular adaptation to abiotic stresses requires coordinated regulation in gene expression directed by complex mechanisms. This study used the activation tagging system to identify novel salt stress-responsive genes. The study selected 9 activation tagging lines that showed salt stress-tolerant phenotypes during their germination stages. Thermal asymmetric interlaced-PCR (TAIL-PCR) was used to identify the T-DNA tagging sites on the Arabidopsis genome in selected activation tagging lines, including AT7508, AT7512, AT7527, AT7544, AT7548, and AT7556. RT-PCR analysis showed that ClpC2/HSP93-III (At3g48870), plant thionin family (At2g20605), anti-muellerian hormone type-2 receptor (At3g50685), vacuolar iron transporter family protein (At4g27870), and microtubule-associated protein (At5g16730) were activated in AT7508, AT7512, AT7527, AT7544, and AT7556, respectively. Interestingly, in AT7548, both the genes adjacent to the T-DNA insertion site were activated: Arabinogalactan protein 13 (AGP13) (At4g26320) and F-box/RNI-like/FBD-like domains-containing protein (At4g26340). All of the seven genes were newly identified as salt stress-responsive genes from this study. Among them, the expression of ClpC2/HSP93-III, AGP13, F-box/RNI-like/FBD-like domains-containing protein gene, and microtubule-associated protein gene were increased under salt-stress condition. In addition, AT7508, AT7527, and AT7544 were more tolerant to salt stress than wild type at seedling development stage, functionally validating the screening results of the activation tagging lines. Taken together, our results demonstrate that the activation tagging system is useful for identifying novel stress-responsive genes.