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991.
三角酵母D—氨基酸氧化酶基因的克隆,测序及表达 总被引:1,自引:0,他引:1
利用跨越内含子的PCR技术,从三角酵母(Trigonopsisvariabilis)变种FA110中扩增得到D氨基酸氧化酶基因(daao),并通过TA克隆的方法将其克隆至pGEMT载体。序列测定结果表明,所得daao基因的5′端内含子已被删除,基因总长度为1071bp,它与Trigonopsisvariabilis的D氨基酸氧化酶同源性达983%,与Fusariumsolani和Rhodotorulagracilis的同源性分别是389%和308%。为提高表达水平,又将此基因转移至高表达载体pET28b上,在大肠杆菌BL21(DE3)中进行诱导表达。经IPTG诱导,目的蛋白的产生量可占菌体总蛋白量的46%,分子量约为38kD。D氨基酸氧化酶的活力可达802u/L。 相似文献
992.
Castro Jorge Gómez José M. García Daniel Zamora Regino Hódar José A. 《Plant Ecology》1999,145(1):115-123
For two years, the seed rain and magnitude of seed losses due to predation were evaluated in Scots pine forests in southern Spain. The Crossbill was the most important pre-dispersal predator, consuming more than 80% of ripening seeds. In addition, other birds, mainly Tits and Siskin, also consumed seeds just before seed dispersal, reaching values of 16 and 51% losses in 1996 and 1997, respectively. Seed rain was monitored in different microhabitats (under pine canopies, under shrubs and in open areas), and was most intense under the canopy of mother plants both years. Post-dispersal seed predators (rodents and birds) consumed up to 96% of seeds reaching the ground. Both pre- and post-dispersal seed predators preferentially harvested filled seeds. Post-dispersal predation was similarly intense in all microhabitats, so predators did not change the spatial distribution of the seed rain. These high predation rates were constant between years, localities and habitats (woodland and treeline). We hypothesize that this high rate of seed predation is a major factor limiting the regeneration of these relict populations of Scots pine in its southernmost limit. 相似文献
993.
T. Sasaki Natalia A. Pronina M. Maeshima I. Iwasaki N. Kurano S. Miyachi 《Plant biology (Stuttgart, Germany)》1999,1(1):68-75
Abstract: The number and cross-sectional area of vacuoles in Chlorococcum littorale cells visualized with a differential interfer ence fluorescence microscope increased after their transfer from air to 40% CO2 . An immunological observation indicated that the level of subunit B of vacuolar H*ATPase also increased under 40% CO2 conditions. The activity of nitrate-sensitive ATP-ase associated with the vacuolar membrane was 2–fold higher in 40% CO2 -- grown cells than in air-grown cells. The effects of inhi bitors on the ATPase activity confirmed that these activities were derived from vacuolar-type H-ATPase. These results sug gest that vacuole development associated with that of vacuolar H+ -ATPase occurred during the acclimatization of C. littorale cells to extremely high CO2 conditions. 相似文献
994.
高压力对限制性内切酶活性的影响 总被引:1,自引:0,他引:1
以质粒pSPORT1为底物研究了高压力对Ⅱ型限制性内切酶HindⅢ和XbaⅠ反应的影响。高压力未引起两酶底物碱基特异性的改变,但二者反应活力均随压力升高而逐渐下降,XbaⅠ对高压力更敏感。引起HindⅢ和XbaⅠ限制性内切酶活性完全丧失的压力分别为200和180MPa,半失活压力分别为130和75MPa。 相似文献
995.
蜂毒肽在磷脂膜上取向的高效液相色谱和质谱研究 总被引:1,自引:0,他引:1
利用脂质体模型系统研究了跨膜电位对蜂毒肽在磷脂磷上取向的影响,采用高效液相色谱与质谱技术相结合方法,分析了蜂毒肽与磷脂膜作用后的胰蛋白酶酶解产物,结果发现,当蜂毒肽分子与没有跨膜电位的脂质体结合后,它的所有酶切位点都能够酶有效切断,当蜂毒肽与带负向膜电全的脂质体结合后,其N端的一个酶切位点被封闭,从而说明跨膜电位造成了蜂毒肽在膜上的重瓣取向。 相似文献
996.
The influence of high temperature (33℃) on embryogenesis in isolated microspore culture of Chinese cabbage (Brassica campestris spp. pekinensis ) was investigated by microscpopy of FDA and DAPI. The microspores cultured at constant temperature of 25 ℃ lost their viability quickly and only few viable microspores were found after 7 days of culture. The morphology of the cultured microspores became as turgescent as the "rugby" which was similar to the mature pollen of the Chinese cabbage. The first nuclear division of the microspores was asymmetric. The microspores lost their capacity of embryogenesis under such condition. In contrast, when the microspores were cultured at 33℃ for 24 h before they were transfered to the culture condition of 25 ℃, their developmental pattern was changed. Some of the microspores could remain viable even for 7 days in culture, they became rounded off. The symmetric nuclear division pattern was induced. The frequency of such division was about 40%. Of the several new cell division types observed, the symmetric type was more frequent (55%) than others. The microspores treated under 33℃ were able to form embryoids via embryogenesis. The critical period of high temperature treatment on microspore culture of Chinese cabbage was about the initial 12 h, if the cell division index of microspore was concerned, but the period was the initial 24 h if the frequency of embryogenesis was considered. 相似文献
997.
Ileana Manduteanu Dan Simionescu Agneta Simionescu Maya Simionescu 《Journal of cellular and molecular medicine》2021,25(20):9483-9495
Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non-diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic-hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes-induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD. 相似文献
998.
32℃高温对天蚕(Antheraea yamamai)卵黄发生影响明显,其中影响程度与开始经受32℃处理时天蚕发育阶段有关。结茧后第1天开始即受32℃处理时,脂肪体和血淋巴中卵黄原蛋白(Vg)与可溶性蛋白含量均低于受26℃处理的;化蛹后第1天开始即受32℃处理时,脂肪体中Vg滴度与26℃下的基本无明显差异,但血淋巴和卵巢中Vg或卵黄磷蛋白含量(Vt)均低于26℃的;而在化蛹后第6天开始受32℃处理时,脂肪体和血淋巴中Vg含量与26℃的无明显差异,卵巢中Vt则明显高于26℃的。此外,曾就化蛹后第1或6天开始受32℃处理后脂肪体、血淋巴和卵巢中可溶性蛋白含量的变化作了检测。建议在饲育或保护制种用茧蚕时,老熟幼虫和化蛹初期的蚕蛹不宜接触32℃高温。 相似文献
999.
早籼稻米垩白形成中的生理生化变化特性 总被引:13,自引:0,他引:13
以早籼多垩白品种泸红早1号、浙733和少垩白品种中优早3号、舟优903及中籼中引85为材料,在自然高温条件下对水稻灌浆过程中胚乳内含物质(如淀粉、可溶性糖等)和酶(淀粉磷酸化酶、Q酶)活性的连续变化进行测定。结果表明,不同垩白度品种其胚乳内部物质增长的时间进程和酶活性的变化存在差异,由此造成灌浆动态明显不同,并导致垩白形成的差异。 相似文献
1000.
Darlene S. S. Lim Marianne S. V. Douglas John P. Smol David R. S. Lean 《International Review of Hydrobiology》2001,86(1):1-22
The limnological features that characterize the shallow ponds (<2 m deep) and lakes (>2 m deep) on Bathurst Island, Nunavut, Canada were examined through chemical analyses and multivariate statistical methods as part of a larger on‐going survey to document and monitor environmental changes in these remote and sensitive areas. All sites were relatively oligotrophic and alkaline. Nutrient ratios indicated that nitrogen could be limiting algal growth to a greater degree than phosphorus in over 63% of the sites. Principal components analysis (PCA) was used to explore the patterns of variation in the limnological dataset. The three dominant limnological gradients were: major ion content and dissolved organic carbon (DOC) levels along Axis 1; and pH along Axis 2. 相似文献