• Journal of Wetlands Research
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• 제25권2호
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• pp.159-165
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• 2023

This study measured the ecological niche overlap between two deciduous oak species(Quercus acutissmia and Q. dentata) according to the change in growth responses after treating with the moisture and nutrient contents of the soil at four gradients, and interpreted the degree of competition between the two oak species by ordination method. In the moisture environment gradient, the ecological niche overlap of the two species was high in the photosynthesis-related leaf organs and low in plant architecture such as shoot length. In addition, in case of competition between two oaks, Q. dentata was remarkably dominant in soil moisture gradient, but Q. acutissimia slightly was slightly advantageous over Q. dentata in the soil nutrient gradient. These results show that even in a similar taxonomical group growing in a similar habitat, the response to the organ system of the plant varies depending on the type of environment factor, resulting in different competitive differences among plants.

• Journal of Ecology and Environment
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• 제38권4호
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• pp.493-503
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• 2015

This study analyzed how spatial distribution of Himantormia lugubris is affected by the microenvironment in the Antarctic Specially Protected Area (ASPA) No. 171 located in the Barton Peninsula of King George Island that belongs to the maritime Antarctic. In order to determine the population structure of H. lugubris growing in Baekje Hill within ASPA No. 171, we counted the individuals of different size groups after dividing the population into 5 growth stages according to mean diameter as follows: ≤ 1 cm, 1-3 cm, 3-5 cm, 5-10 cm, and ≥ 10 cm. The count of H. lugubris individuals in each growth stage was converted into its percentage with respect to the entire population, which yielded the finding that stages 1 through 5 accounted for 32.8%, 25.3%, 15.9%, 22.5%, and 3.5%, respectively. This suggests that the population of H. lugubris in ASPA No. 171 has a stable reverse J-shaped population structure, with the younger individuals outnumbering mature ones. The mean density of H. lugubris was 17.6/0.25 m², mean canopy cover 13.3%, and the mean dry weight 37.8 g/0.25 m². It began to produce spore in the sizes over 3 cm, and most individuals measuring 5-10 cm were adults with sexually mature apothecia. The spatial distribution of H. lugubris was highly heterogeneous. The major factors influencing its distribution and performance were found to be the period covered by snow, wind direction, moisture, size of the substrate, and canopy cover of Usnea spp. Based on these factors, we constructed a prediction model for estimating the spatial distribution of H. lugubris. Conclusively, the major factors for the spatial distribution of H. lugubris were snow, wind, substrate and the competition with Usnea spp. These results are important for understanding of the distribution in the maritime Antarctic and evolution of H. lugubris that claims a unique life history and ecological niche.

• Journal of Periodontal and Implant Science
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• 제30권3호
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• pp.675-687
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• 2000

Multiple periodontal pathogens sequentially colonize the subgingival niche during the conversion from gingivitis to destructive periodontal disease. An animal model of sequential immunization with key periodontal pathogens has been developed to determine whether T and B lymppocyte effector functions are skewed and fail to protect the host from pathogenic challenge. The present study was performed to evaluate immunomodulatory effect of exposure to Fusobacterium nucleatum(F. nucleatum) prior to Porphyromonas gingivalis(P. gingi - valis). Group 1(control) mice were immunized with phosphate-buffered saline, Group 2 were immunized with F. nucleatum prior to P. gingivalis, while Group 3 were immunized P. gingivalis alone. All the T cell clones derived from Group 2 demonstrated type 2 helper T cell clone(Th2 subsets), while those from Group 3 mice demonstrated Th1 subsets. Exposure of mice to F . nucleatum prior to P. gingivalis interfered with opsonophagocytosis function of sera against P. gingivalis. In adoptive T cell transfer experiments, in vivo protective capacity type 2 helper T cell clones(Th2) from Group 2 was significantly lower than type 1 helper T cell clones(Th1) from Group 3 against the lethal dose infection of P. gingivalis. Western blot analysis indicated the different pattern of recognition of P .gingivalis fimbrial proteins between sera from Group 2 and Group 3. In conclusion, these study suggest that colonization of the subgingival niche by F .nucleatum prior to the periodontal pathogen, P. gingivalis, modulates the host immune responses to P. gingivalis at humoral, cellular and molecular levels.

• Korean Journal of Cognitive Science
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• 제28권3호
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• pp.173-191
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• 2017

The theories of cultural evolution hold subtly or clearly different stances about definition of culture, pattern of cultural evolution, biases that affect cultural evolution, and relationship between culture and organism. However, the cultural evolution theories have a common problem to solve: As the evolutionary theory of life tries to explain the early steps and the origin of life, the cultural evolution theories also must explain the early steps of the cultural evolution and the role of the human capability that makes cultural evolution possible. Therefore, explanations of the human's unique traits including the cultural ability are related to determine which one is the most plausible among many cultural evolution theories. Theories that tried to explain human uniqueness commonly depict the coevolution of gene (organism) and culture. We will explicitly call the niche construction theory and the dual inheritance theory the 'gene-culture co-evolutionary theory'. In these theories, the most important concept is the 'concept of positive feedback'. In this paper, we distinguish between core positive feedback and marginal positive feedback, according to whether the trait that the concept of positive feedback explains is the trait of human uniqueness. Both types of positive feedback effectively explain the generality of human uniqueness and the diversity of human traits driven by cultural groups. However, this positive feedback requires an end, in contrast to negative feedback which can be continued in order to maintain homeostasis. We argue that the co-evolutionary process in the gene-culture co-evolutionary theories include only the positive feedback, not covering the cultural evolution after the positive feedback. This thesis strives to define the coevolution concept more comprehensively by suggesting the potential relationships between gene and culture after the positive feedback.

• 한국해양학회지
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• 제30권5호
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• pp.436-441
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• 1995

Final biomass yields (peak optical density) and growth rates (divisions/day) of seven clones of Skeletonema costatum from Korean coastal waters were measured to understand their intraspecific variations in the light intensity niche component under 25$^{\circ}C$ condition. Daily growth rates of 6 out of 7 S. costatum clones were maximum at 6000 lux while that of YS4, a neritic clone, was maximum at 9000 lux. The final biomass yields of 4 out of the 7 s. costatum clones were maximum at the lowest light intensity of 2000 lux. Minimum final biomass yields were found at 9000 lux in all the S. costatum clones other than an estuarine clone, HDC9. The intraspecific variations of the mean growth rate and mean final biomass yield under each of the three different light intensities in terms of the coefficient of variation were not greater than 10% in any of the 7 S. costatum clones.

• Reproductive and Developmental Biology
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• 제37권2호
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• pp.79-83
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• 2013

Matrix metalloproteinases (MMPs) have been known to affect to cell migration, proliferation, morphogenesis and apoptosis by degrading the extracellular matrix. In the previous studies, undifferentiated mouse embryonic stem cells (ESCs) were successfully proliferated inside the extracellular matrix (ECM) analog-conjugated three-dimensional (3D) poly ethylene glycol (PEG)-based hydrogel. However, there is no report about MMP secretion in ESCs, which makes it difficult to understand and explain how ESCs enlarge space and proliferate inside 3D PEG-based hydrogel constructed by crosslinkers containing MMP-specific cleavage peptide sequence. Therefore, we investigated what types of MMPs are released from undifferentiated ESCs and how extracellular signals derived from various niche conditions affect MMP expression of ESCs at the transcriptional level. Results showed that undifferentiated ESCs expressed specifically MMP2 and MMP3 mRNAs. Transcriptional up-regulation of MMP2 was caused by the 3D scaffold, and activation of integrin inside the 3D scaffold upregulated MMP2 mRNAs synergistically. Moreover, mouse embryonic fibroblasts (MEFs) on 2D matrix and 3D scaffold induced upregulation of MMP3 mRNAs, and activation of integrins through conjugation of extracellular matrix (ECM) analogs with 3D scaffold upregulated MMP3 mRNAs synergistically. These results suggest that successful proliferation of ESCs inside the 3D PEG-based hydrogel may be caused by increase of MMP2 and MMP3 expression resulting from 3D scaffold itself as well as activation of integrins inside the 3D PEG-based scaffold.

• Korean Journal of Plant Resources
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• 제19권4호
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• pp.555-561
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• 2006

This study was carried out to investigate the suitable place for growth by analyzing the ecological environment of multi-use tree species to be spontaneous in Chungbuk Province, and derive the suitable place for forestation. At the test of the independence of multi-use tree species, as the significant correlation of the other tree species except Quercus acutissima - Zanthoxylum schinifolium was different by the survey location, it is concluded that the share relation of the ecological niche among tree species is largely influenced not only by the affinity of tree species but the growth environment. As the result of the correlation analysis between environment factors and tree clusters, it was analyzed that tree clusters were much influenced by the topography and the altitude among the variable environment factors; the topography, altitude, the direction of hillside, the slope and the number of tree species appearing. It was investigated that the cluster of Acer mono - Betula costata was distributed to the valley from low hillside to have high altitude, and the clusters of Kalopanax pictus - Ulmus davidiana var. japonica and Fraxinus rhynchophylla - Rhus trichocarpa were sporadically distributed to broad location because their geographical adaptation powers are high.

• Korean journal of applied entomology
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• 제51권4호
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• pp.317-323
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• 2012

Fragmented urban forests, as green islands within urban area, are the primary habitats for a vast number of different organisms inhabiting large cities. The areas of the urban forests are usually small, and hence, the proportion of the forest edge is relatively high. It is therefore expected that overall butterfly diversity may be lower than that of suburban or rural forests, and that those of grassland species, forest edge species, and generalist species with a wider niche breadth may be richer. Butterflies were surveyed weekly by the line transact method in order to characterize the butterfly community of the Hongneung Forest, a fragmented urban forest in Seoul. Butterfly richness of the study forest is much lower than those of main forests around or in Seoul. Grassland species, forest edge species, and generalist species were found to be richer, which was in agreement with the expected patterns of urban butterfly communities. Also, an endangered species, Spindasis takanonis, was observed in the Hongneung Forest, showing that urban forests play important roles for conservation of rare species.

• Journal of Korean Society on Water Environment
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• 제27권1호
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• pp.73-87
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• 2011

An abnormal mono-specific bloom of the cyanobacterium Microcystis aeruginosa had developed at a specific location (transitional zone, monitoring station of Hoenam) in Daecheong Reservoir from middle of July to early August, 2001. The maximum cell counts during the peak bloom reached 1,477,500 cells/mL, which was more than 6~10 times greater than those at other monitoring sites. The hypothesis of this study is that the timing and location of the algal bloom was highly correlated with the local environmental niche that was controled by physical processes such as hydrodynamic mixing and pollutant transport in the reservoir. A three-dimensional, coupled hydrodynamic and ecological model, ELCOM-CAEDYM, was applied to the period of development and subsequent decline of the bloom. The model was calibrated against observed water temperature profiles and water quality variables for different locations, and applied to reproduce the algal bloom event and justify the limiting factor that controled the Microcystis bloom at R3. The simulation results supported the hypothesis that the phosphorus loading induced from a contaminated tributary during several runoff events are closely related to the rapid growth of Microcystis during the period of bloom. Also the physical environments of the reservoir such as a strong thermal stratification and weak wind velocity conditions provided competitive advantage to Microcystis given its light adaptation capability. The results show how the ELCOM-CAEDYM captures the complex interactions between the hydrodynamic and biogeochemical processes, and the local environmental niche that is preferable for cyanobacterial species growth.

• The Korean Journal of Pesticide Science
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• 제4권3호
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• pp.68-74
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• 2000

Penicillium oxalicum (PENOX) has shown the potential as a biocontrol agent(5CA) for control of a weed, clover(Trifolium repens L.) in grass plots. The bioherbicidal activity may be due to germinative and growth capacities and substrate availability of the agent over a range of environmental factors. The influences of different water activities($0.94{\sim}0.995\;a_w$) and temperatures($18{\sim}30^{\circ}C$) on mycelial growth, conidial germination, sporulation oil 2% MEA(malt extract agar) adjusted to different water activities with glycerol, and carbon source utilization using BIOLOG GN MicroPlate were determined in vitro. Decreases in $a_w$ on MEA caused a reduction in mycelial growth and conidial germination depending on temperature. The mycelial growth of PENOX was greatest at $30^{\circ}C/0.995\;a_w$. At some lowered water activity($0.97\;a_w$), the growth was similar between 25 and $30^{\circ}C$, and considerably decreased at lowered temperature($20^{\circ}C$). The germination rate was also greatest at $30^{\circ}C/0.995\;a_w$. Lag phase times for PENOX at $18^{\circ}C$ on MEA were >6hrs at tile whole $a_w$ level tested, and at 18 and $25^{\circ}C$ they were >18hrs and >12hrs at $0.94\;a_w$, respectively. However, its sporulation was some better at $0.97\;a_w$ than $0.995\;a_w$ or $0.94\;a_w$, and better at $20^{\circ}C$ than $30^{\circ}C$. In contrast, the number of carbon sources(niche size) utilized by PENOX varied with $a_w$ and temperature. Under some water stress condition($0.95\;a_w$), the agent utilized smaller number of carbon sources than $0.995\;a_w$ depending on temperature. The niche size at 0.995 and $0.95\;a_w$ were highest at $25^{\circ}C$, and showed 86 and 65, respectively. At $30^{\circ}C$, the niche size at 0.995 and $0.95\;a_w$ showed 84 and 50, respectively. There was no carbon source utilized by PENOX at $0.90\;a_w$ regardless of temperature. These information of tile fungal ecophysiology will be useful for the effective development of BCA.