【作者】 任杰；

【导师】 王荣富； 吴李君；

【作者基本信息】 安徽农业大学 ， 生物物理， 2006， 硕士

【摘要】 本研究以拟南芥columbia生态型种子为材料,把拟南芥种子在4℃的无菌水中浸泡3天,无菌环境下用细镊子得以轻松分离无损伤拟南芥胚胎/胚,并使发芽达到同步化。建立了能够满足实验要求的拟南芥胚无损伤剥离方法。模式植物拟南芥的种胚很小,其胚具有细胞、根、叶等器官形成分化的基本模式,是研究个体水平辐射的理想材料。高传能线密度α粒子在拟南芥胚中的穿透深度有限,用SRIM软件模拟的结果约为30微米。预备实验表明,由于α粒子的穿透力有限,150Gy的α粒子辐射拟南芥种子,根的长度无显著变化。本研究用拟南芥胚作为辐照材料,辐射剂量分别为0Gy、1Gy、10Gy、100Gy,研究了高LETα粒子照射植物个体的辐射生理学效应及其机理,在植物个体水平研究了辐射生物学家感兴趣的α粒子引起的辐射生物学效应,对评估α粒子对非人类健康的影响具有一定的参考价值。该研究表明,1Gy、10Gy、100Gy的α粒子注入拟南芥胚后,胚的发芽率均达97%以上,α粒子注入对胚生活力的影响体现在发芽势的高低上,与对照相比1Gy的剂量处理刺激拟南芥胚的萌发,10Gy、100Gy的剂量处理抑制了拟南芥胚的萌发。主根长度的变化与发芽势一致。α粒子注入使主根的重力敏感性降低,尤其是100Gy的α粒子注入使在竖直的培养基上生长的拟南芥主根呈“S”型生长,在0～100Gy的范围内,根的弯曲度与剂量相关。Vc清除过氧化氢实验表明:100Gy的α粒子注入的拟南芥胚,种在含0.2mM Vc的MS培养基上,根的重力敏感性恢复正常。根的弯曲模拟实验表明,侧面外源释放过氧化氢能够诱导拟南芥根的弯曲。这暗示了α粒子注入引起的重力敏感性、根长等变化与过氧化氢有关。过氧化氢酶、过氧化物酶的活性及丙二醛的含量随剂量的增加而增加,超氧化物岐化酶的活性在低剂量时变化不显著,在100Gy时显著降低。100Gy高剂量的α粒子辐射使叶绿素含量降低。分子探针CM- H2DCFDA定位ROS的实验结果表明,100Gy剂量处理的拟南芥根部有较多的绿色荧光表达。该研究显示α粒子注入拟南芥胚可能通过诱导信号分子过氧化氢的增加,引起生理水平的变化。更多还原

【Abstract】 The Arabidopsis thaliana columbia seeds are dipped in sterile water at 4℃for three days and the Arabidopsis embryos are dissected easily with a slim forceps under the sterile condition.Arabidopsis thaliana is a small dicotyledonous plant that is widely used as a model organism in plant biology. Arabidopsis embryo represents a simple cellular pattern comprised of a few basic tissues and prototypes of leaf-and root-like organs. These tissues are generated in a series of highly reproducible stages that imply tight control of orientation and frequency of cell division as well as cell morphology and differentiantion. For the short penetrate distance of -particle (30μm), our pre-experiment showed that no difference was found between 150Gy -particle treated Arabidopsis seeds and control group. The irradiation doses adopted in this study were 0Gy, 1Gy, 10Gy and 100Gy. This study about -particle on the multicellular organism has an important role to evaluate the potential risk of alpha radiation to non-human biota.The effects of -particle radiation on Arabidopsis embryos was studied in the present research. The results indicated that the germination percentage of embryos was not affected with irradiation at all doses. As the germination speed, it increased with 1Gy -particle treatment (82.5%), 11.4% higher than that of control. However, with the increase of the dosage, the germination speed decreased accordingly, showing that at 100Gy -particle treatment, the germination speed is about 29.3%. Interestingly, the effects of radiation on root length were consistent with that of germination speed. Moreover, the root gravitropism of 100Gy treatment showed more“S”type curves compared with non-irradiated controls. The mechanism study showed that the root gravitropism recovered while cultured in the MS medium containing 0.2mM Vc, which indicated that H2O2 might joined the process of gravitropism. Furthermore, during the shooting period of Arabidopsis, we detected the content of MDA and the activity of SOD and CAT. It showed that CAT activity and MDA content increased with the increase of doses, while SOD activity of 100Gy treatment decreased 12.6% compared with that of control. All these studies indicated that the induced increase of H2O2 signal molecules after -particle radiation may be the mechanism of radiation physiological effects.更多还原