【摘要】 以能量为20 keV,剂量为2.6×1015～15.6×1015ions/cm2的N+注入狐米草胚性愈伤组织.低 剂量时,组织内长效自由基含量随剂量明显上升,非电解质外渗加快,可溶性蛋白含量与组织存活率均明 显降低.随着剂量的升高,MDA开始积累,SOD、POD活性被迅速激活,自由基得到及时清除,非电解质外渗率与可溶性蛋白含量维持在较低水平,组织存活率在下降过程中有小幅回升.较高实验剂量下,保护酶活性被抑制,细胞膜透性进一步加大,自由基、MDA测定值下降,可溶性蛋白含量与组织存活率降低至最低值.外加甘露醇培养,发现组织内自由基降低后,各生理指标与存活率均有所好转.实验证明:N+注入过程中,自由基积累是影响狐米草组织存活率的重要因素,SOD、POD等抗氧化系统的应激性表达在一定程度上能缓解离子注入对组织的损伤.更多还原

【Abstract】 To explore the free radical responses of organisms under ions beams irradiation, N beam with energy of 20 keV and dose from 2.6 × 1015 ions/cm2 to 15.6×1015 ions/cm2 were irradiated into embryonic calli of Spartina patens. When the dose was low, the content of soluble protein and surviving rate of the calli decreased with accumulation of stable free radical, and non-electrolytic substance (NES) filtered out of the calli quickly. Within the middle dose range, malondialdehyde (MDA) began to accumulate. Excessive superoxide dismutase (SOD) and peroxidase (POD) were activated. With removal of free radical in time, soluble protein content sustained at a lower level and NESexosmosis rate did not increase. Surviving rate of the calli had a slight restoration instead of decrease in the mass. When the dose reached even higher, SOD and POD were inhibited and cell membrane became more permeable, with the decrease of free radical, MDA, exosmosis rate of NES and soluble protein. Surviving rate of the calli dropped to the lowest level. When rnannitol was added into the cultural media, the damage of N+ beam irradiation to the calli was released. In general, the accumulation of free radical was an important factor threatening the survival of S. patens calli under N+ irradiation. As the antioxidant system including SOD and POD was activated in time, and free radical was removed to some degree, the damage caused by free radical did not follow the linear relationship with ions dose.更多还原