试验旨在探究日粮中添加过瘤胃率不同的裂壶藻粉(SP)和包被裂壶藻粉(CSP)对高产荷斯坦奶牛生产性能、健康状况及乳中二十二碳六烯酸(DHA)含量的影响。将36头泌乳(130±10.9)d和产奶量(32.36±2.14)kg的荷斯坦奶牛随机分成3组,...试验旨在探究日粮中添加过瘤胃率不同的裂壶藻粉(SP)和包被裂壶藻粉(CSP)对高产荷斯坦奶牛生产性能、健康状况及乳中二十二碳六烯酸(DHA)含量的影响。将36头泌乳(130±10.9)d和产奶量(32.36±2.14)kg的荷斯坦奶牛随机分成3组,即对照组(基础日粮)、150 SP组(基础日粮+每日补饲150 g SP)、300 CSP组(基础日粮+每日补饲300 g CSP)。预试期1周,正试期7周。结果表明:150 SP组和300 CSP组乳脂率和乳糖率低于对照组(P<0.05),但3个组间的4%校正乳无差异;在奶牛日粮中添加SP和CSP可增加牛奶中DHA含量(P<0.05),饲喂7周后,150 SP组、300 CSP组乳中DHA含量分别可达25、44 mg/100 mL;饲喂5周后,150 SP组、300 CSP组DHA转化率分别稳定在14%、24%左右;与对照组相比,300 CSP组奶牛血清总胆固醇含量下降(P<0.05),低密度脂蛋白胆固醇含量有下降趋势,高密度脂蛋白胆固醇含量有所升高。由此可见,在奶牛日粮中添加150 g SP或者300 g CSP能显著提高原料乳中DHA含量,对奶牛生产性能、健康状况无不利影响,以添加300 g CSP的饲喂效果更佳。展开更多
A TiAl-Nb composite was prepared by spark plasma sintering （SPS） at 1250 °C and 50 MPa for 5 min from prealloyed TiAl powder and elemental Nb powder in a molar ratio of 9：1 for improving the fracture toughness...A TiAl-Nb composite was prepared by spark plasma sintering （SPS） at 1250 °C and 50 MPa for 5 min from prealloyed TiAl powder and elemental Nb powder in a molar ratio of 9：1 for improving the fracture toughness of TiAl alloy at room temperature. The microstructure, phase constitute, fracture surface and fracture toughness were determined by X-ray diffractometry, electron probe micro-analysis, scanning and transmission electron microscopy and mechanical testing. The results show that the sintered samples mainly consist of γ phase, O phase, niobium solid solution （Nbss） phase and B2 phase. The fracture toughness is as high as 28.7 MPa？m1/2 at room temperature. The ductile Nbss phase plays an important role in absorbing the fracture energy in front of the cracks. Moreover, B2 phase can branch the propagation of the cracks. The microhardness of each phase of the composite was also tested.展开更多
Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The ...Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer （FRET） was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results （1） The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. （2） Blue and yellow fluorescences were detected in the transfected cells. （3） FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. （4） Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. （5） Aβ-deposition was widespread in the cell. （6） Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer＇s disease. Intracellular Aβ accumulation brings deleterious effects on cells.展开更多
[Objective] Pollen mother cell miosis and male gametophyte development of pumpkin were observed in this study, to provide some cytological basis for pumpkin anther or microspore culture. [Method] Ehrlich＇s hematoxyli...[Objective] Pollen mother cell miosis and male gametophyte development of pumpkin were observed in this study, to provide some cytological basis for pumpkin anther or microspore culture. [Method] Ehrlich＇s hematoxylin staining-methyl salicylate clearing technique was used for observation and research of the variation of cell structure and chromosomal behavior during pollen mother cell miosis and male gametophyte development of ‘Tianhong＇ pumpkin. [Result] The meiosis in pollen moth- er cells of pumpkin was simultaneous cytokinesis. In the process of nuclear division, nuclear membrane and nucleolus of pumpkin pollen mother cells gradually disappeared in the metaphase I and reappeared in telophase I , phragmoplast formed between the two generated crescent-shaped nuclei without cell wall, the phragmoplast gradually disappeared in the metaphase II and reappeared in telophase II. Phragmoplast spread outward from the center of spindle during the second division was connected with that formed on the central interface of two nuclei during the first division, cell wall of microspores generated from periphery to center. Most of the tetrads contained four sub-cells while a few contained extra small cells. During the period of uniuclete microspore at periphery, the single nucleolus split into 2-3 or more small nucleoli, mature pollen grain was two-celled. Mononucleate pollen cells were mostly appeared in the flower buds with length of 1.0-2.0 cm, which could be used as an important indicator to collect materials for anther or microspore culture. [Conclusion] This study laid the foundation for research of the cytogenetics of pumpkin.展开更多
文摘试验旨在探究日粮中添加过瘤胃率不同的裂壶藻粉(SP)和包被裂壶藻粉(CSP)对高产荷斯坦奶牛生产性能、健康状况及乳中二十二碳六烯酸(DHA)含量的影响。将36头泌乳(130±10.9)d和产奶量(32.36±2.14)kg的荷斯坦奶牛随机分成3组,即对照组(基础日粮)、150 SP组(基础日粮+每日补饲150 g SP)、300 CSP组(基础日粮+每日补饲300 g CSP)。预试期1周,正试期7周。结果表明:150 SP组和300 CSP组乳脂率和乳糖率低于对照组(P<0.05),但3个组间的4%校正乳无差异;在奶牛日粮中添加SP和CSP可增加牛奶中DHA含量(P<0.05),饲喂7周后,150 SP组、300 CSP组乳中DHA含量分别可达25、44 mg/100 mL;饲喂5周后,150 SP组、300 CSP组DHA转化率分别稳定在14%、24%左右;与对照组相比,300 CSP组奶牛血清总胆固醇含量下降(P<0.05),低密度脂蛋白胆固醇含量有下降趋势,高密度脂蛋白胆固醇含量有所升高。由此可见,在奶牛日粮中添加150 g SP或者300 g CSP能显著提高原料乳中DHA含量,对奶牛生产性能、健康状况无不利影响,以添加300 g CSP的饲喂效果更佳。
基金Project (2011CB605505) supported by the National Basic Research Program of ChinaProject (2008AA03A233) supported by the Hi-tech Research and Development Program of China
文摘A TiAl-Nb composite was prepared by spark plasma sintering （SPS） at 1250 °C and 50 MPa for 5 min from prealloyed TiAl powder and elemental Nb powder in a molar ratio of 9：1 for improving the fracture toughness of TiAl alloy at room temperature. The microstructure, phase constitute, fracture surface and fracture toughness were determined by X-ray diffractometry, electron probe micro-analysis, scanning and transmission electron microscopy and mechanical testing. The results show that the sintered samples mainly consist of γ phase, O phase, niobium solid solution （Nbss） phase and B2 phase. The fracture toughness is as high as 28.7 MPa？m1/2 at room temperature. The ductile Nbss phase plays an important role in absorbing the fracture energy in front of the cracks. Moreover, B2 phase can branch the propagation of the cracks. The microhardness of each phase of the composite was also tested.
文摘Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer （FRET） was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results （1） The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. （2） Blue and yellow fluorescences were detected in the transfected cells. （3） FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. （4） Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. （5） Aβ-deposition was widespread in the cell. （6） Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer＇s disease. Intracellular Aβ accumulation brings deleterious effects on cells.
基金Supported by Project of Jiangsu Provincial Department of Education (JHZD06-7)Qing Lan Project of Colleges and Universities in Jiangsu Province (2008 No.30)~~
文摘[Objective] Pollen mother cell miosis and male gametophyte development of pumpkin were observed in this study, to provide some cytological basis for pumpkin anther or microspore culture. [Method] Ehrlich＇s hematoxylin staining-methyl salicylate clearing technique was used for observation and research of the variation of cell structure and chromosomal behavior during pollen mother cell miosis and male gametophyte development of ‘Tianhong＇ pumpkin. [Result] The meiosis in pollen moth- er cells of pumpkin was simultaneous cytokinesis. In the process of nuclear division, nuclear membrane and nucleolus of pumpkin pollen mother cells gradually disappeared in the metaphase I and reappeared in telophase I , phragmoplast formed between the two generated crescent-shaped nuclei without cell wall, the phragmoplast gradually disappeared in the metaphase II and reappeared in telophase II. Phragmoplast spread outward from the center of spindle during the second division was connected with that formed on the central interface of two nuclei during the first division, cell wall of microspores generated from periphery to center. Most of the tetrads contained four sub-cells while a few contained extra small cells. During the period of uniuclete microspore at periphery, the single nucleolus split into 2-3 or more small nucleoli, mature pollen grain was two-celled. Mononucleate pollen cells were mostly appeared in the flower buds with length of 1.0-2.0 cm, which could be used as an important indicator to collect materials for anther or microspore culture. [Conclusion] This study laid the foundation for research of the cytogenetics of pumpkin.
