• Journal of Ecology and Environment
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• v.44 no.3
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• pp.162-177
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• 2020

Background: Ecologists have achieved much progress in the study of mechanisms that maintain species coexistence and diversity. In this paper, we reviewed a wide range of past research related to these topics, focusing on five theoretical bodies: (1) coexistence by niche differentiation, (2) coexistence without niche differentiation, (3) coexistence along environmental stress gradients, (4) coexistence under non-equilibrium versus equilibrium conditions, and (5) modern perspectives. Results: From the review, we identified that there are few models that can be generally and confidently applicable to different ecological systems. This problem arises mainly because most theories have not been substantiated by enough empirical research based on field data to test various coexistence hypotheses at different spatial scales. We also found that little is still known about the mechanisms of species coexistence under harsh environmental conditions. This is because most previous models treat disturbance as a key factor shaping community structure, but they do not explicitly deal with stressful systems with non-lethal conditions. We evaluated the mainstream ideas of niche differentiation and stochasticity for the coexistence of plant species across salt marsh creeks in southwestern Denmark. The results showed that diversity indices, such as Shannon-Wiener diversity, richness, and evenness, decreased with increasing surface elevation and increased with increasing niche overlap and niche breadth. The two niche parameters linearly decreased with increasing elevation. These findings imply a substantial influence of an equalizing mechanism that reduces differences in relative fitness among species in the highly stressful environments of the marsh. We propose that species evenness increases under very harsh conditions if the associated stress is not lethal. Finally, we present a conceptual model of patterns related to the level of environmental stress and niche characteristics along a microhabitat gradient (i.e., surface elevation). Conclusions: The ecology of stressful systems with non-lethal conditions will be increasingly important as ongoing global-scale climate change extends the period of chronic stresses that are not necessarily fatal to inhabiting plants. We recommend that more ecologists continue this line of research.

• Management & Information Systems Review
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• v.18
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• pp.115-132
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• 2006

The main findings of this study are summarized as follows; 1) For medium-small size Family Restaurant(FR) in the FR market, nowadays, survival is the key issue. If the medium-small size FR is to survive and continue to grow under this competitive environment, it must pursued the efficiency of management with niche marketing strategy. 2) This study is to describe the niche marketing strategy for medium-small size FR. Strategic niche marketing must be based on the target market, market positioning and strategic marketing mix. 3) Medium-small size FR needs to develop the marketing mix factors for the niche marketing strategy. It needs to make customers understand what the FR differs from current and potential competitors. Essentially the medium-small size FR must take a competitive advantage. Hence it will appeal to a substantial number of the segments customers. 4) In using niche marketing strategy, a medium-small size FR must establish the objectives, select the tools, develop the decisions on product differentiation, market segmentation and positioning under various strategic niche marketing factors 5) By carrying out the niche marketing strategy on the target market, customer's desire can be further fulfilled. When management efficiency is improved, we can better cope with changing environment.

• Archives of design research
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• no.18
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• pp.37-48
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• 1996

For succesful political advertisements the role of mutual communications between advertisers and their targets (i.e. voters) should be magnified, which must be based on the understanding of voter's life-style including the trends of daily life, their philosophy and attitude toward the contemporary matters. During the campaign period for the last parliamentry election the most important issue was nothing but who could be the best representer of their region without any political considerations compared to previous election and the decision made by voters has been evaluated as one of most brilliant ones so far. One thing to note from the last election is that many new faces have been high lighted and that could not have been possible if they could not differentiate their campaign from one of unchanged senior politicians by calling more attentions of voters to them by scrutinizing competitors' election pledges. The differentiation strategy in election campaigns is basically detecting small signs of changes in voters life\ulcornerstyle, bringing them into relief and provoking voters attentions to the election and advertiser. In this sense niche marketing strategy is the differentiating strategy itself and it can be a useful guide in political advertisement for the triumph of advertiser in elections as well as for heathy and fresh political environments on the basis increased attentions of voters. In this paper, aiming at further development of the niche marketing in political advertisements we propose questions whether the niche marketing in the last parliamentary election was introduced on the basis of concept of differentation by analysing last election's strategies targeted at voters specific dispositions.

• Journal of Life Science
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• v.31 no.9
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• pp.856-861
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• 2021

CD82/KAI1, identified as a metastasis suppressor, was initially known only as a molecular facilitator, but its various functions have recently been revealed. CD82 plays an important role in the stem-progenitor cell, angiogenesis, and muscle. We would like to introduce the recently reported functions and roles of CD82 in this review. CD82 is a member of the tetraspanin family, which consists of four transmembrane domains. The interaction between CD82 and cell adhesion molecules suppresses the metastasis of cancer. CD82 regulates the cell cycle of stem-progenitor cells in the stem cell niche. In the bone marrow, CD82 is expressed on long-term repopulating hematopoietic stem cells (LT-HSCs), which show multipotent differentiation potential. The interaction between CD82 and Duffy antigen receptor for chemokines (DARC) induces quiescence in LT-HSCs. CD82 also regulates Rac1 activity, resulting in the homing and engraftment of HSCs into the bone marrow niche. Besides, CD82 maintains the differentiation potential of muscle stem cells and prevents angiogenesis by inhibiting the expression of cytokines, such as IL-6 and VEGF and adhesion molecules in endothelial cells. CD82 is a key membrane protein that distinguishes the hierarchy of stem-progenitor cells, and is also important for amplification and verification of cellular resources. Further studies on the function of CD82 in various organs and cells are expected to advance cell biology and cell therapy.

• Proceedings of the Korea Society of Costume Conference
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• 2003.10a
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• pp.43-43
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• 2003

The first purpose of this study is to establish the database of color palette and coordination for casual wear and sports wear market by analyzing and comparing the characteristics of practical colors for each market segment. Furthermore, this study will make the proposal of the differential color palette and color coordination that will be used for effective color planning for the niche market.

• Biomolecules & Therapeutics
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• v.24 no.1
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• pp.9-18
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• 2016

Bone matrix is properly maintained by osteoclasts and osteoblasts. In the tumor microenvironment, osteoclasts are increasingly differentiated by the various ligands and cytokines secreted from the metastasized cancer cells at the bone metastasis niche. The activated osteoclasts generate osteolytic lesions. For this reason, studies focusing on the differentiation of osteoclasts are important to reduce bone destruction by tumor metastasis. The N-myc downstream-regulated gene 2 (NDRG2) has been known to contribute to the suppression of tumor growth and metastasis, but the precise role of NDRG2 in osteoclast differentiation induced by cancer cells has not been elucidated. In this study, we demonstrate that NDRG2 expression in breast cancer cells has an inhibitory effect on osteoclast differentiation. RAW 264.7 cells, which are monocytic preosteoclast cells, treated with the conditioned media (CM) of murine breast cancer cells (4T1) expressing NDRG2 are less differentiated into the multinucleated osteoclast-like cells than those treated with the CM of 4T1-WT or 4T1-mock cells. Interestingly, 4T1 cells stably expressing NDRG2 showed a decreased mRNA and protein level of intercellular adhesion molecule 1 (ICAM1), which is known to enhance osteoclast maturation. Osteoclast differentiation was also reduced by ICAM1 knockdown in 4T1 cells. In addition, blocking the interaction between soluble ICAM1 and ICAM1 receptors significantly decreased osteoclastogenesis of RAW 264.7 cells in the tumor environment. Collectively, these results suggest that the reduction of ICAM1 expression by NDRG2 in breast cancer cells decreases osteoclast differentiation, and demonstrate that excessive bone resorption could be inhibited via ICAM1 down-regulation by NDRG2 expression.

• BMB Reports
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• v.56 no.9
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• pp.482-487
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• 2023

Hematopoiesis is regulated by crosstalk between long-term repopulating hematopoietic stem cells (LT-HSCs) and supporting niche cells in the bone marrow (BM). Here, we describe the role of KAI1, which is mainly expressed on LT-HSCs and rarely on other hematopoietic stem-progenitor cells (HSPCs), in niche-mediated LT-HSC maintenance. KAI1 activates TGF-β1/Smad3 signal in LT-HSCs, leading to the induction of CDK inhibitors and inhibition of the cell cycle. The KAI1-binding partner DARC is expressed on macrophages and stabilizes KAI1 on LT-HSCs, promoting their quiescence. Conversely, when DARC+ BM macrophages were absent, the level of surface KAI1 on LT-HSCs decreases, leading to cell-cycle entry, proliferation, and differentiation. Thus, KAI1 acts as a functional surface marker of LT-HSCs that regulates dormancy through interaction with DARC-expressing macrophages in the BM stem cell niche. Recently, we showed very special and rare macrophages expressing α-SMA+ COX2+ & DARC+ induce not only dormancy of LT-HSC through interaction of KAI1-DARC but also protect HSCs by down-regulating ROS through COX2 signaling. In the near future, the strategy to combine KAI1-positive LT-HSCs and α-SMA/Cox2/DARC triple-positive macrophages will improve the efficacy of stem cell transplantation after the ablative chemo-therapy for hematological disorders including leukemia.

• Journal of Korean Society of Forest Science
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• v.105 no.4
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• pp.414-421
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• 2016

Fourteen Acer pseudosieboldianum populations in South Korea were used to estimate genetic diversity, genetic differentiation and genetic relationships using seven AFLP primer combinations. The average of effective alleles ($A_e$), the proportion of polymorphic loci (%P) and Shannon's diversity index (I) was 1.4, 82.2% and 0.358, respectively. The expected heterozygosity ($H_e$) under Hardy-Weinberg equilibrium was 0.231 and the expected heterozygosity (Hj) from Bayesian inference was 0.253. The level of genetic diversity was moderate compared to those of Genus Acer and lower than those of other species having similar ecological niche and life history. The inbreeding coefficient within populations ($F_{IS}$) from Bayesian method was 0.712 and it could be influenced by selfing or biparental inbreeding to induce homozygote excess. The level of genetic differentiation was 0.107 from AMOVA (${\Phi}_{ST}$) and 0.110 from Bayesian method (${\Phi}^{II}$). The genetic differentiation was lower than those of other species having similar ecological niche and life history. Ulleungdo population had the lowest level of genetic diversity and was genetically the most distinct population from others in the study. We consider that founder effect and genetic drift might be occurred to reduce genetic diversity and then the geographical isolation might interrupt gene flow to aggravate it.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.415-422
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• 2019

Human epidermal stem cells(ESCs) residing in the basement membrane of the skin have an important role in maintenance of skin homeostasis of epidermal layer. Although, ESCs provide new cells to repair damaged tissue in response to tissue injury, subsets of stem cells remain in the quiescent state protected from differentiation and senescence for prolonged survivals. In this perspective, the stem cell niche, which is specific microenvironment composed of niche cells and an extracellular matrix(ECM), supplies the relevant signal to save stem cells from microenvironmental damages. The expression of stemness marker on the surface of ESCs contributes to the attachment on their ECM of the basement membrane, which lead to growth potential and apoptotic resistance against environmental stimuli. In this study, we observed that UV irradiation, a major factor of environmental stimuli, reduced the expression of α2, β1 and α6 integrin in ESCs. Rhus Semialata M extract(RSE) showed inhibitory effect on the UVB-induced reduction of integrin expression. Furthermore, RSE could upregulate the expression of Col-IV and Laminin, which contribute to the attachment of ESCs. These results indicated that RSE could be a potent ingredient for the protection of ESCs from UV irradiation by increasing the expression of integrin and substrate ECM components at their niche.

• Journal of International Society for Simulation Surgery
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• v.4 no.1
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• pp.1-8
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• 2017

In the field of tissue engineering, researches have been actively conducted to regulate stem cell fate by understanding the interaction between cell and materials. This approach is expected as a promising therapeutic method in the future medicine by utilizing differentiation of stem cells into desired cells or tissues using biomaterial. For this regenerative medicine, there exist lots of attempts to construct optimized structures of various shapes and sizes that can regulate the stem cell fate. In this review, we will empathize the topographic effect as stem cell niche on the mesenchymal stem cell (MSC) response (cell attachment, proliferation, and differentiation) according to the shape and size of the structure of the substrates, and comprehensively analyze the importance and the effect of shape and size of the surface topography.