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101.
Direct detection of beta-1,3-glucanase isozymes on polyacrylamide electrophoresis and isoelectrofocusing gels 总被引:2,自引:0,他引:2
A procedure to assay isozymes of beta-1,3-glucanase directly on polyacrylamide gel electrophoresis (PAGE) and isoelectrofocusing (IEF) gels by using 2,3,5-triphenyltetrazolium chloride is described. The reagent reacts with reducing sugars released by beta-1,3-glucanases from the substrate laminarin. Acidic and neutral isozymes of beta-1,3-glucanase were detected and quantified on 17.5% native PAGE gels run with an anodic buffer system. A significant linear relationship (alpha = less than 0.01, R = 0.991) was observed between amounts of beta-1,3-glucanase loaded and intensity of bands stained with the reagent on native PAGE gels. A full isozyme pattern was obtained on 7.5% IEF gels with a pH range of 3.5-9.5. The IEF gels were heated in a microwave oven during the staining process to minimize diffusion. 相似文献
102.
为了阐明非磷酸化肌球蛋白在平滑肌细胞迁移中的作用,研究探讨了非磷酸化肌球蛋白是否介导了血小板衍生生长因子(PDGF)诱导豚鼠脑基底动脉平滑肌细胞(GbaSM-4)的迁移。研究结果显示,20ng/ml以下剂量的PDGF可诱导GbaSM-4细胞发生迁移,此时肌球蛋白轻链(MLC20)磷酸化水平无变化。该迁移作用可被肌球蛋白特异性抑制剂blebbistatin所拮抗。应用RNA干扰技术抑制肌球蛋白轻链激酶表达,经免疫印迹检测经果显示,MLC20的磷酸化水平发生了显著下降;但对PDGF诱导的迁移作用无影响;在RNA干扰后blebbistatin也可抑制其迁移作用。体外ATP酶活性测定结果显示,blebbistatin对从平滑肌中提取的非磷酸化肌球蛋白的ATP酶活性有明显的抑制作用,其主要作用位点位于肌球蛋白头的头部S1。上述结果提示,非磷酸化的肌球蛋白参与了PDGF诱导的平滑肌细胞迁移。 相似文献
103.
104.
银杏叶提取物对糖尿病大鼠心肌损伤的防护作用 总被引:9,自引:0,他引:9
目的:研究银杏叶提取物(EGb)对糖尿病大鼠心肌的防护作用.方法:用光镜和透射电镜观察EGb对糖尿病大鼠心肌的形态学改变,并测定心肌组织内超氧化物歧化酶(SOD)、一氧化氮合酶(NOS)、结构型一氧化氮合酶(cNOS)、诱导型一氧化氮合酶(iNOS)的活性及一氧化氮(NO)、丙二醛(MDA)的含量.结果:糖尿病大鼠心肌光镜下主要表现为心肌细胞空泡变性及心肌纤维局灶性溶解;电镜下主要表现为心肌线粒体肿胀,嵴变短,肌原纤维溶解;SOD活性下降,NOS、iNOS活性及MDA、NO含量增高.EGb治疗组病变明显减轻,EGb治疗组心肌组织内SOD活性明显高于糖尿病组,NOS、iNOS活性及MDA、NO含量低于糖尿病组.结论:EGb可能通过抗脂质过氧化作用和降低NO水平而对糖尿病心肌产生保护作用. 相似文献
105.
K. Wang Y. N. Sun J. Y. Liu L. Zhang Y. Ye L. X. Lin Y. Q. Yan Z. P. Chen 《Biological trace element research》2009,130(1):72-85
Thyroid function ultimately depends on appropriate iodine supply to the gland. There is a complex series of checks and balances
that the thyroid uses to control the orderly utilization of iodine for hormone synthesis. The aim of our study is to evaluate
the mechanism underlying the effect of iodine excess on thyroid hormone metabolism. Based on the successful establishment
of animal models of normal-iodine (NI) and different degrees of high-iodine (HI) intake in Wistar rats, the content of monoiodotyrosine
(MIT), diiodotyrosine (DIT), T4, and T3 in thyroid tissues, the activity of thyroidal type 1 deiodinase (D1) and its (Dio1) mRNA expression level were measured. Results showed that, in the case of iodine excess, the biosynthesis of both MIT and
DIT, especially DIT, was increased. There was an obvious tendency of decreasing in MIT/DIT ratio with increased doses of iodine
intake. In addition, iodine excess greatly inhibited thyroidal D1 activity and mRNA expression. T3 was greatly lower in the HI group, while there was no significant difference of T4 compared with NI group. The T3/T4 ratio was decreased in HI groups, antiparalleled with increased doses of iodine intakes. In conclusion, the increased biosyntheses
of DIT relative to MIT and the inhibition of thyroidal Dio1 mRNA expression and D1 activity may be taken as an effective way to protect an organism from impairment caused by too much
T3. These observations provide new insights into the cellular regulation mechanism of thyroid hormones under physiological and
pathological conditions. 相似文献
106.
Climatic and technological ceilings for Chinese rice stagnation based on yield gaps and yield trend pattern analysis 总被引:4,自引:0,他引:4
Climatic or technological ceilings could cause yield stagnation. Thus, identifying the principal reasons for yield stagnation within the context of the local climate and socio‐economic conditions are essential for informing regional agricultural policies. In this study, we identified the climatic and technological ceilings for seven rice‐production regions in China based on yield gaps and on a yield trend pattern analysis for the period 1980–2010. The results indicate that 54.9% of the counties sampled experienced yield stagnation since the 1980. The potential yield ceilings in northern and eastern China decreased to a greater extent than in other regions due to the accompanying climate effects of increases in temperature and decreases in radiation. This may be associated with yield stagnation and halt occurring in approximately 49.8–57.0% of the sampled counties in these areas. South‐western China exhibited a promising scope for yield improvement, showing the greatest yield gap (30.6%), whereas the yields were stagnant in 58.4% of the sampled counties. This finding suggests that efforts to overcome the technological ceiling must be given priority so that the available exploitable yield gap can be achieved. North‐eastern China, however, represents a noteworthy exception. In the north‐central area of this region, climate change has increased the yield potential ceiling, and this increase has been accompanied by the most rapid increase in actual yield: 1.02 ton ha?1 per decade. Therefore, north‐eastern China shows a great potential for rice production, which is favoured by the current climate conditions and available technology level. Additional environmentally friendly economic incentives might be considered in this region. 相似文献
107.
Lin Fabin Wu Dihang Lin Chenxin Cai Huihui Chen Lina Cai Guofa Ye Qinyong Cai Guoen 《Neurochemical research》2020,45(4):709-719
Neurochemical Research - Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) has been proposed as a treatment strategy for gait disorder in patients with Parkinson’s disease... 相似文献
108.
为大量制备β-NGF,构建了一种稳定、高效表达重组人神经生长因子(Recombinant human nerve growth factor,rh-β-NGF)的真核表达载体及含该重组载体的HEK293细胞株。首先,构建重组质粒p CMV-β-NGF-IRES-dhfr并转染至HEK293细胞系,用MTX加压筛选和有限稀释法进行选择,获得高效表达rh-β-NGF的单克隆重组细胞株;随后逐步降低血清培养,最终使细胞株完全适应无血清培养基并稳定表达rh-β-NGF;SDS-PAGE分析该表达产物,可见相对分子质量约13 k Da的条带,纯度大于50%,经质谱法测定得到其肽图谱与理论序列完全匹配,接着利用离子交换层析和分子筛层析纯化rh-β-NGF;最后进行重组细胞株表达效率和表达稳定性检测,表明重组细胞株可稳定、高效表达rh-β-NGF,其分泌效率大于20 pg/(cell?d),并能诱导PC12细胞的分化,具有良好的生物学活性。 相似文献
109.
海藻糖及其在生物工程方面的应用 总被引:4,自引:0,他引:4
自海藻糖发现以来对其化学性质、生理功能、作用机理、代谢途径等已进行了较为深入的研究,其分子生物学的研究也渐渐兴起。研究表明海藻糖能提高生物体对干旱、低温、高温、pH、盐渍等逆境条件下的抗性。离体试验表明海藻糖能保护生物膜、蛋白质的结构并能保持逆境下的酶活性,同时,外源海藻糖同样对生物体有保护作用。由于海藻糖具有这些独特的生物学功能,它已在许多方面得以应用,可作为食品工业的一种添加剂和甜味剂,使干燥食品在得水后保持原有的色、香、味;也可作为医药工业的非特异性生物制品和生化药品保护剂,使其在常温下保存,从而降低运输与储存费用;另外,在农业研究中可利用现代分子生物技术培育表达海藻糖的转基因作物,提高农作物的抗旱、抗冻等抗逆性能。 相似文献
110.
一种模拟昆虫种群动态的改进的变维矩阵模型 总被引:1,自引:0,他引:1
提出了一种模拟昆虫种群动态的改进的变维矩阵模型,该模型以发有历期为维数,采用分解与合成的方法变维,并考虑了个体间的发育差异。经模拟检验,模型模拟结果略优于徐汝梅等(1981)变维矩阵模型的结果。 相似文献