【作者】 商桂敏；

【导师】 元英进；

【作者基本信息】 天津大学 ， 生物化工， 2004， 硕士

【摘要】 以悬浮培养南方红豆杉 Y 系细胞为例，以研究磁场作用对细胞生长与次级代谢表达的影响为目的，开展了以下研究工作： 首先，利用物理学知识建立两类磁场体系，即 50Hz 正弦时变电磁场(ACMF)和直流稳恒电磁场(DCMF)，系统考察了两类磁场作用下正常培养细胞的生长与次级代谢表达的动态变化。研究表明两类磁场均有利于细胞初生代谢，DCMF的影响效果明显好于 ACMF。对比正常培养条件和磁场处理条件下红豆杉细胞活力动力学变化曲线，发现两者之间的细胞活力改变值随时间成很好的二次多项式关系。细胞生物量及胞内蛋白含量均得到提高。两类磁场下细胞紫杉醇产量均得到不同程度的提高，但影响机理不同：ACMF 作用下紫杉醇产量的提高是由于该磁场提高细胞生物量所致，而 DCMF 则是由于它激活细胞防御反应，使细胞合成紫杉醇的能力上升。 采用酸胁迫处理细胞，研究细胞生长状态对磁场生物学效应的影响。DCMF作用下细胞活力及生物量的变化规律揭示，指数生长期的细胞更耐受磁场的伤害。胞外培养液电导率和 pH 值的变化说明，酸胁迫作用下细胞的物质跨膜运输更易受磁场影响，使细胞更快适应外界不利环境。细胞受到的酸胁迫越大，磁场生物学效应越明显。 在培养体系中添加诱导子水杨酸，研究 DCMF 与诱导共同作用下细胞次级代谢表达规律。磁场使水杨酸诱导下细胞次级代谢表达提前：磁场和水杨酸共同作用的第 2 天即出现紫杉醇的大量累积，分别为对照组和水杨酸单独处理组的 3.4 和 2.5 倍；共同处理组紫杉醇产量最大值于第 6 天出现，比水杨酸单独处理组的最高值出现时间提前 2 天。但共同作用组紫杉醇的最大产量仅为水杨酸单独处理组最大产量的 0.75 倍，表明磁场和水杨酸共同作用并没有增加紫杉醇产量。 比较不同条件下 DCMF 的生物学效应，揭示该磁场可能的作用机理。磁场增加了细胞能量，加速了物质的跨膜运输，从而导致细胞活力的上升和初生代谢更为旺盛。磁场抑制了细胞胞内过氧化物酶的比活力，导致胞内过氧化物酶受到抑制，丙二醛含量上升，膜脂过氧化加剧。更多还原

【Abstract】 The effects of magnetic field on the growth and secondary metabolism of Taxuschinensis var. mairei in suspension cultures were investigated. The detail studies weredone from the aspects as follows. The natural cells were exposed to two magnetic fields (MF), sinusoidalalternating current magnetic field (ACMF, 50 Hz, 3.5 mT) and direct currentmagnetic field (DCMF, 3.5 mT). The results show the two MFs are both beneficial tothe cell growth and the intensity of bioeffects the DCMF was much stronger than thatof the ACMF. The variations of the cell viability in the two MFs compared to thecontrol are correlated as quadratic relations. The cell biomass and intracellular proteinwere all enhanced by the MFs. Both MFs enhanced taxol production, but themechanism is different. The enhancement of taxol production in ACMF is ascribed tothe increase of the cell biomass, while the abrupt rise of taxol production in the latephase of cell growth in DCMF might indicate an activation of the defense reaction. HCl of different concentration was added to the medium in order to study theinfluences of the physiologic state on the bioeffects of the DCMF. The results showthat the cells in the late growth phase have better endurance to the hurt of the MF. Theobvious change of the medium pH and conductivity indicated that the ion transportunder the intimidation of HCl was easier to be affected by the DCMF. The higher theconcentration of HCl was, the stronger the bioeffects of the magnetic field were. The cooperation of the DCMF and salicylic acid (SA) brought the secondarymetabolism forward. The taxol yields were 3.4 fold (SA) and 1.2 fold (control)respectively in the 2 th days. The maximum of taxol (MF+SA) occurred in the 6 thday, which was 2 days ahead of that of the SA treated cells. But the value was only0.75 fold of that of SA treated ones. We ascribe the enhancement of the cell growth induced by DCMF to the increaseof the cell energy and the promotion of the ion transport brought by the magneticfield. The inhibition of the POD relative activity might account for the enhancementof the malondialdehyde (MDA) and the peroxidation of the cell membrane.更多还原