• 한국과학교육학회지
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• 제25권4호
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• pp.472-479
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• 2005

이 연구는 과학교사의 탐구과학능력발달의 전문성을 위하여 교육현장에서 실질적으로 적용 가능한 SSCS 프로그램을 이용하여 적용하고, 그에 대한 교사들의 인식을 조사하였다. 과학교사의 탐구능력발달에 대한 전문성을 위한 일련의 프로그램으로, 과학교사 28명이 SSCS 워크샵과 연수를 통하여 SSCS 모듈을 개발하고, 시연하는 일련의 과정으로 구성되었다. 과학 교사들의 탐구능력발달 모듈을 개발, 그리고 적용과 효과에 대한 인식이라는 두 가지의 연구 문제에 대하여 조사하였다. 과학 교사의 탐구능력발달 전문성은 SSCS 모델을 적용한 프로그램 개발과 수업 기술이 포함되며, 이것은 교사의 SSCS 모델 활용을 위하여 선결되어야 할 문제점으로 지적되었다. 교사들이 인식하는 프로그램 적용의 구체적인 효과는 교사의 과학 및 과학 학습에 대한 스스로의 동기 유발, 탐구적 문제해결 능력 함양, 탐구 과학 수업에 대한 자신감 함양 등이 제시되었다. 그러나, 프로그램의 과정이 요구하는 많은 시간과 노력과 다양한 분야에 대한 전문적 지식과 상식은 실질적인 어려운 점으로 지적되었다. 한편 교사들은 교육과정 과학 시간상의 제약 실질적인 학습효과에 대한 불확실성, 프로그램 개발의 어려움, 다양한 수업 전략의 필요로 인하여 SSCS 프로그램의 학교 현장 적용에 다소 제한적인 관점을 나타냈다.

• Anatomy and Cell Biology
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• 제57권2호
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• pp.163-171
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• 2024

In the last decade, melatonin has gained recognition as a potent scavenger and an effective antioxidant capable of neutralizing free radicals, including reactive oxygen species. Additionally, it exhibits anti-apoptotic properties. In this review, we will examine a compilation of articles that explore the cellular signaling function of melatonin on spermatogonial stem cells (SSCs) and adjacent cells such as Sertoli and Leydig cells. These cells play a crucial role in the proliferation of SSCs both in vitro and in vivo. In this review, we analyze the function of melatonin in the proliferation of SSCs from other aspects. For this purpose, we examine the articles based on the presence of melatonin on SSCs in four groups: As a supplement in SSCs medium culture, SSCs three-dimensional culture system, SSCs freezing medium, and as a therapeutic factor in vivo. Mechanisms of growth and proliferation of SSCs were considered. The purpose of this study is to investigate the potential effects of melatonin as a powerful antioxidant or growth stimulant for SSCs, both in vivo and in vitro.

• Reproductive and Developmental Biology
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• 제38권2호
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• pp.85-91
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• 2014

Despite many researches related with in-vitro culture of porcine spematogonial stem cells (SSCs), adherent culture system widely used has shown a limitation in the maintenance of porcine SSC self-renewal. Therefore, in order to overcome this obstacle, suspension culture, which is known to have numerous advantage over adherent culture, was applied to the culture of porcine SSCs. Porcine SSCs retrieved from neonatal testes were suspension-cultured for 5 days or 20 days, and characteristics of suspension-cultured porcine SSCs including proliferation, alkaline phosphatase (AP) activity, and self-renewal-specific gene expression were investigated and compared with those of adherent-cultured porcine SSCs. As the results, the suspension-cultured porcine SSCs showed entirely non-proliferative and significantly higher rate of AP-positive cells and expression of self-renewal-specific genes than the adherent-cultured porcine SSCs. In addition, long-term culture of porcine SSCs in suspension condition induced significant decrease in the yield of AP staining-positive cells on post-day 10 of culture. These results showed that suspension culture was inappropriate to culture porcine SSCs, because the culture of porcine SSCs in suspension condition didn't stimulate proliferation and maintain AP activity of porcine SSCs, regardless of culture periods.

• Reproductive and Developmental Biology
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• 제37권3호
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• pp.143-148
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• 2013

Spermatogenesis is initiated from spermatogonial stem cells (SSCs) that has an ability of self-renewal and unipotency to generate differentiating germ cells. The objective of this study is to develop the simple method for derivation of SSCs using non-sorting of both spermatogonia and feeder cells. Simply uncapsulated mouse testes were treated with enzymes followed by surgical mincing, and single cells were cultured in stempro-$34^{TM}$ cell culture media at $37^{\circ}C$. After 5 days of culture, aciniform of SSC colony was observed, and showed a strong alkaline phosphatase activity. Molecular characterization of mouse SSCs showed that most of the mouse SSC markers such as integrin ${\alpha}6$ and ${\beta}1$, CD9 and Stra8. In addition, pluripotency embryonic stem cell (ESC) marker Oct4 were expressed, however Sox2 expression was lowered. Interestingly, expression of SSC markers such as Vasa, Dazl and PLZF were stronger than mouse ESC (mESC). This data suggest that generated mouse SSCs (mSSCs) in this study has at least similar biomarkers expression to mESC and mSSCs derived from other study. Immunocytochemistry using whole mSSC colony also confirmed that mSSCs generated from this study expressed SSC specific biomarkers such as c-kit, Thy1, Vasa and Dazl. In conclusion, mSSCs from 5 days old mouse testes were successfully established without sorting of spermatogonia, and this cells expressed both mESC and SSC specific biomarkers. This simple derivation method for mSSCs may facilitate the study of spermatogenesis.

• Molecules and Cells
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• 제37권6호
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• pp.473-479
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• 2014

Spermatogonial stem cells (SSCs, also called germline stem cells) are self-renewing unipotent stem cells that produce differentiating germ cells in the testis. SSCs can be isolated from the testis and cultured in vitro for long-term periods in the presence of feeder cells (often mouse embryonic fibroblasts). However, the maintenance of SSC feeder culture systems is tedious because preparation of feeder cells is needed at each subculture. In this study, we developed a Matrigel-based feeder-free culture system for long-term propagation of SSCs. Although several in vitro SSC culture systems without feeder cells have been previously described, our Matrigel-based feeder-free culture system is time- and cost-effective, and preserves self-renewability of SSCs. In addition, the growth rate of SSCs cultured using our newly developed system is equivalent to that in feeder cultures. We confirmed that the feeder-free cultured SSCs expressed germ cell markers both at the mRNA and protein levels. Furthermore, the functionality of feeder-free cultured SSCs was confirmed by their transplantation into germ cell-depleted mice. These results suggest that our newly developed feeder-free culture system provides a simple approach to maintaining SSCs in vitro and studying the basic biology of SSCs, including determination of their fate.

• 한국수정란이식학회지
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• 제29권3호
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• pp.221-228
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• 2014

Despite that porcine spermatogonial stem cells (pSSCs) have been regarded as a practical tool for preserving eternally genetic backgrounds derived from pigs with high performance in the economic traits or phenotypes of specific human diseases, there were no reports about precise definition of niche conditions promoting proliferation and maintenance of pSSCs. Accordingly, we tried to determine niche conditions supporting proliferation and maintenance of undifferentiated pSSCs for short-term. For these, undifferentiated pSSCs were progressively cultured in different composition of culture medium, seeding density of pSSCs, type of feeder cells and concentration of growth factors, and then total number of and alkaline phosphatase (AP) activity of pSSCs were investigated at post-6 day culture. As the results, the culture of $4{\times}10^5$ pSSCs on mitotically in activated $2{\times}10^5$ STO cells in the mouse embryonic stem cell culture medium (mESCCM) supplemented with 30 ng/ml glial cell line-derived neurotrophic factor (GDNF) was identified as the best niche condition supporting effectively the short-term maintenance of undifferentiated pSSCs. Moreover, the optimized short-term culture system will be a basis for developing long-term culture system of pSSCs in the following researches.

• Preventive Nutrition and Food Science
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• 제9권1호
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• pp.65-70
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• 2004

Side-stream cigarette smoke (SSCS) is a major component of environmental tobacco smoke. The purpose of this study was to investigate the development of lung injury and lipid peroxidation in the lung and liver of immunodeficient (Nude) mice exposed to acute SSCS (a total 5 hours of exposure). The effects of French maritime bark extract (Pycnogeno $l^{ⓡ}$) supplementation of the mice were also determined. SSCS increased pulmonary resistance and lipid peroxidation in these mice. Pycnogeno $l^{ⓡ}$ supplementation increased vitamin E levels in lung and liver. In addition, Pycnogeno $l^{ⓡ}$ attenuated SSCS-mediated lung injury and lipid peroxidation. It appears that the enhanced resistance against SSCS-induced lung injury and lipid peroxidation may be primarily due to the antioxidant property of Pycnogeno $l^{ⓡ}$ in supplemented mice.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1336-1342
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• 2022

Risk-informed safety classification of structures, systems and components (SSCs) is very important for ensuring the safety and economic efficiency of nuclear power plants (NPPs). However, previous methods for safety classification of SSCs do not take the plant operating modes or the operational process of SSCs into consideration, thus cannot concentrate on the safety and economic efficiency accurately. In this contribution, a new method for safety classification of SSCs based on the categorization of plant operating modes is proposed, which considers the NPPs operating history to improve the economic efficiencies while maintaining the safety. According to the time duration of plant configurations in plant operating modes, average importances of SSCs are accessed for an NPP considering the operational process, and then safety classification of SSCs is performed for plant operating modes. The correctness and effectiveness of the proposed method is demonstrated by application in an NPP's safety classification of SSCs.

• Journal of Veterinary Science
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• 제23권2호
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• pp.35.1-35.13
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• 2022

Background: The testis has been reported to be a naturally O2-deprived organ, dimethyloxaloylglycine (DMOG) can inhibit hypoxia inducible factor-1alpha (HIF-1α) subject to degradation under normal oxygen condition in cells. Objectives: The objective of this study is to detect the effects of DMOG on the proliferation and differentiation of spermatogonial stem cells (SSCs) in Bama minipigs. Methods: Gradient concentrations of DMOG were added into the culture medium, HIF-1α protein in SSCs was detected by western blot analysis, the relative transcription levels of the SSC-specific genes were analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Six days post-induction, the genes related to spermatogenesis were detected by qRT-PCR, and the DNA content was determined by flow cytometry. Results: Results revealed that the levels of HIF-1α protein increased in SSCs with the DMOG treatment in a dose-dependent manner. The relative transcription levels of SSC-specific genes were significantly upregulated (p < 0.05) by activating HIF-1α expression. The induction results showed that DMOG significantly increased (p < 0.05) the spermatogenesis capability of SSCs, and the populations of haploid cells significantly increased (p < 0.05) in DMOG-treated SSCs when compared to those in DMOG-untreated SSCs. Conclusion: We demonstrate that DMOG can promote the spermatogenesis activity of SSCs.

• 한국수정란이식학회지
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• 제31권1호
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• pp.89-95
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• 2016

The present study was conduct to examine the $H_2O_2$ expression level and apoptosis-related gene expression levels inporcineskin-derived stem cell-like cells (pSSCs) after adipogenic, chondrogenic, and osteogenic differentiation induction. The pSSCs were obtained by digestion of porcine ear skin biopsy and cultured in each induction medium for 21 to 26 days to induce adipogenic, chondrogenic, and osteogenic differentiation, respectively. The $H_2O_2$ levels of pSSCs after induction culture were evaluated by staining with 2'7'-dichlorodihydrofluorescein diacetate ($H_2DCFDA$). The apoptotic gene expression of pSSCs after induction culture was also estimated by RT-PCR. The pSSCs have a potential to differentiate into three mesodermal cell types (adipocytes, chondrocytes, and osteoblasts). Non-induced control and chondrogenic-induced cells were showed higher $H_2DCFDA$ intensity (P<0.05) than adipogenic- and osteogenic-induced cells. The relative expression of Bax/Bcl-2 level was significantly low (P<0.05) in adipogenic- and osteogenic-induced cells compared to non-induced control. However, there was no difference in the relative expression of Bax/Bcl-2 level among differentiation induction groups. The result of the present study shows that the apoptosis of pSSCs is not detrimentally increased by differentiation induction culture, although chondrogenic-induced pSSCs showed high ROS generation level and apoptotic index similarly to those of non-induced cells.