• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.121-128
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• 2020

Diarrhea is a major public health concern associated with pathogenic Escherichia coli infections. Food-borne pathogenic E. coli can lead to large diarrheal outbreaks and hence, there is a need to estimate the frequency of pathogenic E. coli load in the various types of meat available in markets. In the present study, we classified and characterized diarrheagenic E. coli isolates collected from 399 raw meat samples from retail sources in Korea. Shiga toxin-producing E. coli (STEC) were detected in 11 (9.7%) samples, including nine strains (8.0%) in beef and two strains (1.8%) in chicken. The frequency of the detected virulence markers were as follows: astA, 28.3%; escV,18.6%; eaeA,17.7%; ent, 7.0%; EHEC-hly, 4.4%; stx1, 3.5%; and stx2, 3.5%. We did not observe any typical EPEC, EIEC, or ETEC virulence determinants in any of the samples. The STEC serotype O26 was detected in one sample, but no other serogroups (O91, O103, O128, O157, O145, O111, and O121) were found. Further research is needed to better understand the virulence mechanism of STEC serotypes, their ecology, and prevalence in animals, food, and the environment. These results will help improve risk assessment and predict the sources of food poisoning outbreaks.

• Journal of Species Research
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• v.8 no.3
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• pp.313-317
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• 2019

Bats influence overall ecosystem health by regulating species diversity and being a major source of zoonotic viruses. Hence, there is a need to elucidate their migration, population structure, and phylogenetic relationship. The complete mitochondrial genome is widely used for studying the genome-level characteristics and phylogenetic relationship of various animals due to its high mutation rate, simple structure, and maternal inheritance. In this study, we determined the complete mitogenome sequence of the bird-like noctule (Nyctalus aviator) by Illumina next-generation sequencing. The sequences obtained were used to reconstruct a phylogenic tree of Vespertilionidae to elucidate the phylogenetic relationship among its members. The mitogenome of N. aviator is 16,863-bp long with a typical vertebrate gene arrangement, consisting of 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 putative control region. Overall, the nucleotide composition is as follows: 32.3% A, 24.2% C, 14.3% G, and 29.2% T, with a slight AT bias (61.5%). The base composition of the 13 PCGs is as follows: 30.3% A, 13.4% G, 31.0% T, and 25.2% C. The phylogenetic analysis, based on 13 concatenated PCG sequences, infers that N. aviator is closely related to N. noctula with a high bootstrap value (100%).

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.72-76
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• 2001

Essential hypertension is a heterogeneously multifactorial disease in which blood pressure is harmfully high without overt cause. Both genetic and environmental factors have been implicated in its etiology. In view of the regulatory role of this peptide in the carbohydrate metabolism and renin-angiotensin system, amylin gene has been proposed to a candidate gene for essential hypertension. Therefore, we scanned the amylin gene for mutations in 133 Korean normotensives and 61 essential hypertensives by single-strand conformational polymorphism, and found a single heterozygous S20G missense mutation. However, no significant difference was observed between normotensives and essential hypertensives in the distribution of allele and genotype frequencies of this mutation at the amylin gene (P>0.05). This finding suggests that S20G missense mutation of the amylin gene are unlikely to contribute to the etiology of essential hypertension in the Korean population.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.420-429
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• 2023

This study was designed to examine the immune response in Korean rockfish during water temperature fluctuation and to elucidate the factors contributing to streptococcal pathogenesis in cultured Korean rockfish, S. schlegeli. We investigated cumulative mortality against Streptococcus iniae (FP5228 strain) infection in the exposed Korean rockfish (39.7±5.8 g) to environmentally relevant temperature (Control, 23℃; High temperature, 28℃ and 23℃ and 28℃ with 12 hours interval exchange, 23↔28℃) for 48 hours. Also, the expression of the mRNA related to the immune response genes (heat shock protein 70, interleukin1β, lysozyme g-type and thioredoxin-like 1) were measured in spleen and head kidney by real-time PCR analysis in the exposed fish to thermal stress. In this study, the combined stress with bacterial challenge in fishes exposed to thermal stress lowered the survival rate than that of control (23℃). The cumulative mortality in the group of control, 28℃ and 23↔28℃ was 24%, 24% and 40% (P<0.05), respectively. Also, thermal stress modulated the mRNA level of immune related genes; heat shock protein 70, interleukin-1β, lysozyme g-type and thioredoxin-like 1 in Korean rockfish. The present study indicates that a high and sudden water temperature change affect immune responses and reduce the disease resistance in Korean rockfish.

• Korean Journal of Environment and Ecology
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• v.35 no.4
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• pp.316-335
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• 2021

This study reviewed the change of theory of ecological niche(concepts and definitions) over time to provide a theoretical basis for habitat-related studies of animals and plants. Accordingly, it analyzed and summarized the major discussion trends of ecological niche worldwide in each period from the 1900s to the present. Countries advanced in ecological studies, such as the EU and the USA, have conducted theoretical and empirical studies on the ecological niche since the early 1990s. The concept of the ecological niche was introduced in the early 1900s, developed in the mid-1900s, and advanced from the mid-1900s to the late 1900s. Since the 2000s, the advanced concept has diversified with new developments in technologies and research methods. The factors suggested by theoretical and empirical studies in defining the ecological niche of a species include 1) population dynamics of the target species, 2) all biotic conditions to sustain a population (food relationship and material flow in the food chain), 3) all non-biotic conditions to sustain a population (physical environmental conditions), 4) all direct and indirect interactions between these environmental factors, and 5) response and adaptation mechanisms that include the migratory ability of the target species or genetic diversity and adaptability to change. Unlike such international advancement, there have not been sufficient theoretical, philosophical, and empirical studies of ecological niche in Korea. The concepts and definitions by Greennell, Elton, and Hutchinson were selectively and partially borrowed for empirical studies without full description. Considering that the theory of ecological niche becomes the foundation for habitat-based species conservation and restoration, it is necessary to seek diversification and advancement of theoretical and empirical research and research methods and technological development. It will provide an important foundation for the academic advancement of ecology and for establishing and implementing policies to preserve and restore ecology and biodiversity effectively and successfully in Korea.

• Korean Journal of Environment and Ecology
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• v.36 no.3
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• pp.318-326
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• 2022

The Convention on Biodiversity (CBD) recommends that 17% of the land be designated as a protected area to counter global environmental problems. Korea also realized a need to designate protected areas according to the international level and explain the significance of designating protected areas. Accordingly, studies on ecosystem services are required. In Korea, the protected areas are designated as national parks, provincial parks, and county parks by hierarchy under the Natural Parks Act. However, as priority was on political and administrative aspects, research on ecosystem service value evaluation and habitat management were concentrated in national parks, and provincial and county parks were relatively neglected. Therefore, more studies on provincial and county parks are necessary. In this study, habitat quality for Gajisan Provincial Park, where there were few studies on habitat management and ecosystem service valuation, was evaluated using the InVEST Habitat Quality model among the InVEST models. The analysis results were compared with 16 mountainous national parks. The results showed that the habitat quality value of Gajisan Provincial Park was 0.83, higher than that of the surrounding areas. The analysis of habitat quality in three districts showed 0,84 for the Tongdosa and Naewonsa districts and 0.83 for the Seoknamsa district. By use district, the nature conservation district, the natural environment district, the cultural heritage district, and the park village district had the highest habitat quality value in that order. Compared with the existing habitat quality analysis results of national parks, Gajisan Provincial Park showed naturalness at the level of Mudeungsan National Park. These results can be used as objective data for establishing policies and management plans to preserve biodiversity and promote ecosystem services in provincial parks.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.693-702
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• 2015

In order to identify the species and to reveal the phylogenetic relationship of rook populations found in Jeju-do Province in winter seasons, we determined the sequences of mitochondrial cytochrome c oxidase I (COI) gene and analyzed the genetic structure of maternal lineages and phylogenetic relationship. The rook DNAs were isolated from the post-mortem specimens and plumages collected from agricultural farms in Jeju-do Province including U-do Island. The obtained COI sequences (n=41) showed over 97.0% identities with those previously reported from Corvus frugeligus. Three COI haplotypes (J01-J03) were detected from COI sequences of the rooks obtained in Jeju-do Province but those did not show the site-specific patterns, showing that they might be derived from a common maternal origin. Eight maternal haplotypes were detected from all COI sequences obtained. Among those three haplotypes contained the COI sequences from Northeast Asia including eastern Russia, Mongolia and South Korea. On the other hand, the other five haplotypes contained the COI sequences reported from Central Asia, Middle East, western Russia and European countries. The COI sequences from Jeju-do Province were located on three haplotypes (CF01-CF03) belonging to Northeast Asian rook lineages. The NJ tree showed the distinct branch patterns suggesting two different maternal lineages of C. frugilegus, which proposed as two parapatric subspecies, C. f. frugilegus (Western) and C. f. pastinator (Eastern). These findings using DNA barcoding approaches will be contributed to provide the information about avian fauna for understanding the genetic structure of maternal lineage, phylogenetic relationship and their molecular ecology.

• Journal of Life Science
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• v.27 no.2
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• pp.155-163
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• 2017

Mori Folium, the leaf of Morus alba, is a traditional medicinal herb that shows various pharmacological activities such as antiinflammatory, antidiabetic, antimelanogenesis, antioxidant, antibacterial, antiallergic, and immunomodulatory activities. However, the mechanisms of their inhibitory effects on adipocyte differentiation and adipogenesis remain poorly understood. In the present study, we investigated the inhibition of adipocyte differentiation and adipogenesis by ethanol extracts of Mori Folium (EEMF) in 3T3-L1 preadipocytes. Treatment with EEMF suppressed the terminal differentiation of 3T3-L1 preadipocytes in a dose-dependent manner, as confirmed by a decrease in the lipid droplet number and lipid content through Oil Red O staining. EEMF significantly reduced the accumulation of cellular triglyceride, which is associated with a significant inhibition of pro-adipogenic transcription factors, including sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor-${\gamma}$ ($PPAR{\gamma}$), and CCAAT/enhancer-binding proteins ${\alpha}$ ($C/EBP{\alpha}$) and ${\beta}$ ($C/EBP{\beta}$). In addition, EEMF potentially downregulated the expression of adipocyte-specific genes, including adipocyte fatty acid binding protein (aP2) and leptin. Furthermore, EEMF treatment effectively increased the phosphorylation of the AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase (ACC); however, treatment with a potent inhibitor of AMPK, compound C, significantly restored the EEMF-induced inhibition of pro-adipogenic transcription factors and adipocyte-specific genes. These results together indicate that EEMF has preeminent effects on the inhibition of adipogenesis through the AMPK signaling pathway, and further studies will be needed to identify the active compounds in Mori Folium.

• Korean Journal of Environment and Ecology
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• v.35 no.5
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• pp.438-479
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• 2021

Basic information such as flora and their distribution are the key factors to consider for preserving plant diversity on a regional level. The number of plant species identified through a survey is closely related to the survey area and the number of habitats distributed within the survey area. In this study, we surveyed the flora of Mt. Maryong-san (PH) and Mt. Daeso-san (YH) located in Uljin-gun, Gyeongsangbuk-do, six and nine times, respectively. We planned to include a variety of habitats in the survey routes. As a result, we identified a total of 594 taxa composing of 112 families, 349 genera, 548 species, 10 subspecies, 34 varieties, and 2 formulas in the Mt. Maryong-san (PH) area and a total of 434 taxa composing of 89 families, 270 genera, 400 species, 9 subspecies, and 25 varieties in the Mt. Daeso-san (YH) area. Of the plants observed in the 21 habitats, the plants distributed in the transition zone around the valley and the dry grassland accounted for the highest proportion. The traditional graveyards located on the coast also served as the major habitat for the distribution of some plant species. In the two graveyards, 19 taxa of endemic plant species were surveyed. Moreover, the identified floristic target species included 1 taxon for grade V, 11 taxa for grade IV, and 24 taxa for grade III. A total of 77 taxa of naturalized plants were identified, and four of them were invasive alien plants as designated by the Ministry of Environment. The differences in the plants distributed in the area of Mt. Maryong-san (PH) and Mt. Daeso-san (YH) were mainly due to the difference in the size of each habitat distributed within the survey area. Moreover, it was judged that the entire vicinity of Mt. Daeso-san (YH) was not connected to the surrounding mountains and was an isolated area surrounded by farmland and residential areas.

• Ecology and Resilient Infrastructure
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• v.8 no.1
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• pp.32-43
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• 2021

Multichannel automated chamber systems (MCACs) were developed for the continuous monitoring of soil CO2 efflux in forest ecosystems. The MCACs mainly consisted of four modules: eight soil chambers with lids that automatically open and close, an infrared CO2 analyzer equipped with eight multichannel gas samplers, an electronic controller with time-relay circuits, and a programmable logic datalogger. To examine the stability and reliability of the developed MCACs in the field during all seasons with a high temporal resolution, as well as the effects of temperature and soil water content on soil CO2 efflux rates, we continuously measured the soil CO2 efflux rates and micrometeorological factors at the Nam-san experimental site in a Quercus mongolica forest floor using the MCACs from January to December 2010. The diurnal and seasonal variations in soil CO2 efflux rates markedly followed the patterns of changes in temperature factors. During the entire experimental period, the soil CO2 efflux rates were strongly correlated with the temperature at a soil depth of 5 cm (r2 = 0.92) but were weakly correlated with the soil water content (r2 = 0.27). The annual sensitivity of soil CO2 efflux to temperature (Q10) in this forest ranged from 2.23 to 3.0, which was in agreement with other studies on temperate deciduous forests. The annual mean soil CO2 efflux measured by the MCACs was approximately 11.1 g CO2 m-2 day-1. These results indicate that the MCACs can be used for the continuous long-term measurements of soil CO2 efflux in the field and for simultaneously determining the impacts of micrometeorological factors.