• Imaging Science in Dentistry
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• 제34권3호
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• pp.137-144
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• 2004

Purpose: To investigate the effects of low dose irradiation on the calcium content and calcific nodule formation of the MC3T3-El osteoblastic cell line. Materials and Methods: Cells were irradiated with a single dose of 0.2, 0.4 and 0.6 Gy at a dose rate of 5.38 Gy/min using Cs-137 irradiator. After irradiation, the calcium content and calcific nodule formation were examined on the 1st, 2nd, 3rd and 4th week. Results: We did not find any significant difference of total calcium content after irradiation of 0.2, 0.4 and 0.6 Gy when compared with the unirradiated control group. There was no significant difference of total calcium content between 0.2, 0.4 and 0.6 Gy irradiated groups. We found an increased tendency of the calcific nodule formation after irradiation of 0.2, 0.4 and 0.6 Gy when compared with the unirradiated control group without significant difference of calcific nodule formation between 0.2, 0.4 and 0.6 Gy irradiated groups. Conclusion : The results showed an increased tendency of the calcific nodule formation after low dose irradiation. However, this tendency did not increase with the increase of irradiation dose.

• Journal of Microbiology and Biotechnology
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• 제16권4호
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• pp.531-537
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• 2006

Lactic acid-producing bacteria (LABs) are known to have various beneficial properties for health. However, they are generally considered to have an adverse effect on teeth, since they produce acid. Nonetheless, milk and cheese containing specific LAB strains were recently found to have an inhibitory effect on dental caries in children, with an inhibitory activity towards the growth of Streptococcus mutans suggested as the responsible mechanism. Accordingly, the current study selected a probiotic candidate for oral health and studied its inhibitory mechanism against dental caries. Twenty-two LAB species belonging to eleven genuses were screened for promoting bone nodule formation using direct microscopic examination. Only one isolate, Weissella kimchii strain PL9001, increased the bone nodule formation significantly. The addition of W. kimchii strain PL9001 to bone cells prepared from mouse calvaria increased the bone nodule formation, calcium accumulation, and activity of alkaline phosphatase (the osteoblastic marker). Moreover, W. kimchii strain PL9001 inhibited the invasion of Streptococcus mutans into bone cells, and an organic extract of the culture supernatant of W. kimchii strain PL9001 inhibited the growth of Strep. mutans. Therefore, the results suggest that W. kimchii strain PL9001 can be used as a preventive measure against dental caries. This is the first time that a LAB has been shown to promote bone nodule formation and prevent the invasion of Strep. mutans into bone cells.

• Journal of Plant Biology
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• 제16권3_4호
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• pp.35-39
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• 1973

This investigation was conducted to study the effect of soybean mosaic virus (SMV) on various parameters of nodule formation at different stage of soybean plants. Differences in nodule formation were marked between soybean varieties tested, but nodules were small within soybean varieties infected with SMV. SMV-infection on soybeans were greatly reduced the number, size and weight of nodules, and the earlier the infection of SMV, the greater the reduction of nodules. Maximum reduction(83%) of nodules observed when "Kumkang-Daerip" soybeans were inoculated 2 weeks after seeding, but none occurred 8 weeks or later. Prominent decreases in number of nodules often resulted in an increase in nodu'e sizes in SMV-infected soybean plants.an plants.

• 한국주조공학회지
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• 제23권4호
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• pp.187-194
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• 2003

The effect of rare earth elements (R.E)(from 0.0 to 0.04%) on the microstructure formation and mechanical properties of thin-wall ductile iron castings were investigated. Tensile strength and hardness were decreased with an addition of up to 0.03% rare-earth elements. After addition of more than 0.03%, those were increased. Graphite nodule sizes were the finest, nodule count was the highst regardless of thickness and volume fraction of ferrite was the largest when that was 0.02%. However, the nodule count was decreased with increasing R.E. Futhermore. nodule size increased with increasing thickness and the volume fraction of ferrite decreased as that was increased. Nodularity was increased regardless of the thickness as that was increased. The castings of minium thickness up to 3 mm was possible without the formation of chill.

• 한국작물학회지
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• 제24권2호
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• pp.75-81
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• 1979

우리나라 장여품종을 위함한 15개 대두품종들의 근류균에 대한 친화성과 접종효과를 밝히기 위하여 사경시험을 실시하였던 바 그 얻어진 결과를 요약하면 다음과 같다. 1. 정석은 근류균접종 15일후에도 근류가 형성되지 않았으나 Lindarin #62는 주당 3.0개의 근류가 형성 되었으며 개화기의 근류형성수도 품종간에 크게 차이가 있어서 정석은 주당 37.8대로 가장 적었고 Haman은 주당 122.2개로 가장 많이 형성되었는데 품종간에 유의차가 인정되었다. 2. 개화기까지의 근류형성수에 대한 시기별 근류형성비율은 품종간에 크게 차이가 있었는데 공시품종평균에 있어서는 접종 15일후에 2,1％, 접종30일후에는 60.8％, 그리고 접종 45일후에는 79.8％가 형성되었다. 3. 근류병접종효과는 현저하여 초장, 경태, 근장, 건물중 및 엽록소함량이 무접종구에 비하여 접종구가 크게 증가하여 전체처리 및 품종간, 그리고 접종처리간에 고도로 유의하였는데 다만 엽록소함량과 건물중의 증가추세와는 반드시 일치되지 않았다. 4. 공시품종평균에 있어서 접종구에 대한 무접종구의 몇가지 현질의 형성비율은 초장 94.0％, 건물중 81.6％, 그리고 엽록소의 함량은 66.8％였다.

• Imaging Science in Dentistry
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• 제35권1호
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• pp.1-8
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• 2005

Purpose : To investigate the effects of irradiation on the calcium content and calcific nodule formation in the MC3T3-E1 osteoblastic cell line. Materials and Methods : Cells were irradiated with a single dose of 2,4 and 8 Gy at a dose rate of 5.38 Gy/min using a Cs-137 irradiator. After irradiation, the calcium content and calcific nodule formation were examined on the 1 st, 2nd, 3rd and 4th week. Results : A decreasing dose-dependent tendency of the cell proliferation rate was found in all irradiated groups of this experiment when compared with the unirradiated control group. In accordance with the duration of culture, there was no significant difference in the cell proliferation rate after irradiation of 2 Gy when compared with the unirradiated group, however a decreasing tendency was found in 4 Gy- and 8 Gy-irradiated groups. While an increase in total calcium content after irradiation of 2 Gy was found at week 1, week 2, and week 4, there was a decrease in calcium content at week 1 through 4 in the 8 Gy- irradiated group. Calcific nodule formation was increased in irradiated experimental groups when compared with the unirradiated control group in the 2 Gy-irradiated group, but decreased in the 4 Gy- and 8 Gy-irradiated groups at the same stage. Conclusion : The results showed a mild increasing tendency of the calcific nodule formation after irradiation of 2 Gy. However, a decreased calcific nodule formation in 4 Gy- and 8 Gy-irradiated groups was found. Taken together, the irradiation of 2 Gy mildly activated bone formation, however 4 Gy or 8 Gy suppressed bone formation by decreasing cell numbers in the MC3T3-El osteoblastic cell line.

• The Plant Pathology Journal
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• 제15권2호
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• pp.127-130
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• 1999

Cytological changes of cowpea root at the early stage of root nodule formation (within 5 days after inoculation) were viewed by light and electron microscopy. The root region affected by the rhizobial infection, which was composed of a redial array of cortical cells, had prominent cell divisions, mostly anticlinal in the inner cortical cells and in addition oblique and periclinal in the outer cells. An infected root hair cell (or root hair-producing epidermal cell) had numerous infection threads and degenerated cytoplasm. Module meristem was formed adjacent to the infected root hair cell, and characterized by dense cytoplasm, prominent nucleus, numerous small vacuoles, and increased plastids, containing infection threads as well. Bacterial cells were dividing inside the infection thread, the wall materials of which appeared to be dissolved ad accumulated in small vacuoles. inner cortical cells contiguous to the nodule meristem appeared to be actively dividing and dedifferentiating; however, they were not infected by the rhizobia. These structural characteristics are similar to those in the Bradyrhizobium-soybean association previously reported, and may reflect the similar cytological process in cowpea in the early nodule formation.

• 한국주조공학회지
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• 제19권1호
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• pp.84-90
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• 1999

In this study, CV cast iron was reverse transformed to produce harder second phase surrounding graphite nodules, and then the microstructure and related mechanical properties of the reverse transformed CV cast iron were investigated by using optical microscopy and by carrying out hardness, tension and impact test. The formation of hard second phase surrounding graphite nodules increased the hardness in CV cast iron. The marked increase in hardness was resulted from the formation of martensite surrounding graphite nodule. It is expected from these results that the formation of martensite surrounding graphite nodule would improve the wear resistance of CV cast iron. The formation of both martensite and pearlite surrounding graphite nodule improved the tensile properties. Impact properties were decreased with increasing the volume fraction of hard second phase. However, the reduced impact properties could be recovered through phase transformation of martensite into pearlite and sorbite by tempering.

• Molecules and Cells
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• 제40권1호
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• pp.17-23
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• 2017

Mitogen-activated protein kinase (MAPK) signaling cascades play critical roles in various cellular events in plants, including stress responses, innate immunity, hormone signaling, and cell specificity. MAPK-mediated stress signaling is also known to negatively regulate nitrogen-fixing symbiotic interactions, but the molecular mechanism of the MAPK signaling cascades underlying the symbiotic nodule development remains largely unknown. We show that the MtMKK5-MtMPK3/6 signaling module negatively regulates the early symbiotic nodule formation, probably upstream of ERN1 (ERF Required for Nodulation 1) and NSP1 (Nod factor Signaling Pathway 1) in Medicago truncatula. The overexpression of MtMKK5 stimulated stress and defense signaling pathways but also reduced nodule formation in M. truncatula roots. Conversely, a MAPK specific inhibitor, U0126, enhanced nodule formation and the expression of an early nodulation marker gene, MtNIN. We found that MtMKK5 directly activates MtMPK3/6 by phosphorylating the TEY motif within the activation loop and that the MtMPK3/6 proteins physically interact with the early nodulation-related transcription factors ERN1 and NSP1. These data suggest that the stress signaling-mediated MtMKK5/MtMPK3/6 module suppresses symbiotic nodule development via the action of early nodulation transcription factors.

• 한국산림과학회지
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• 제101권3호
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• pp.443-453
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• 2012

본 연구는 아까시나무 유묘에서 뿌리혹 형성에 가장 적절한 배양토의 종류와 토양의 양료 수준을 구명하기 위해 수행하였다. 상업용 상토, 완숙 혹은 미숙 퇴비, 유기질 비료, 산림용 고형비료, 화학비료 등의 토양 첨가물을 이용하여 질소와 인의 수준을 다양하게 조절한 후 포트에 아까시나무 종묘를 식재하여 3개월 간 온실에서 실험을 실시하여 초기 뿌리혹 형성에 적절한 토양 환경을 조사하였다. 피트모스, 질석, 지올라이트를 함유한 상업용 상토는 높은 보수력으로 인해 초기 활착과 건중량 생산에는 적절하였으나 무기 양료 중 질소(0.052%), 인(91 ppm)의 부족으로 인해 뿌리혹 형성에는 부적합하였다. 퇴비는 미숙 퇴비이건 완숙퇴비이건 구별 없이 뿌리혹 형성에 가장 유리했는데, 질소(0.08-0.21%)와 인(141-1,228 ppm)의 함량이 적절하였지만, 칼륨(0.14-1.58 cmol/kg)의 함량은 부족한 편이었다. 화학(복합)비료는 토양 내 질소(0.14-0.21%), 인(406-618 ppm), 칼륨(1.39-3.13 cmol/kg)의 함량을 적절한 수준으로 유지하여 초기 건중량 생산에는 지장을 주지 않았지만 뿌리혹 형성에는 부적절하였다. 산림용 고형비료는 뿌리혹 형성에 적합한 반면, 유기질 비료는 뿌리혹 형성에 적합하지 않았다. 배양토에는 적절한 수준의 질소(0.05-0.2%)와 인(100-600 ppm)이 함유되어 있을 경우에 초기 뿌리혹 형성이 제대로 이뤄졌다. 아까시나무 유묘의 경우 토양의 질소와 인 중에서 질소보다 인이 초기의 뿌리혹 형성을 더 촉진하는 것으로 판단되었다.