碳离子辐照对四尾栅藻光合色素及抗氧化活性的影响

为了探讨重离子辐照对微藻的生物学效应，实验研究了不同剂量碳离子辐照（10~80 Gy）对四尾栅藻（Scenedesmus quadricauda）光合色素及抗氧化活性的影响，分别测定了辐照后短期内其叶绿素a（Chl a）、叶绿素b（Chl b）和类胡萝卜素含量、脂质过氧化物丙二醛(MDA)含量及超氧化物歧化酶（SOD）活性。结果显示：(1)较低剂量（10~20 Gy）辐照后，光合色素含量变化较小或无显著变化,中等剂量（40~60 Gy）辐照后，光合色素含量显著升高，之后又回落，恢复至正常水平，高剂量（80 Gy）辐照后，光合色素含量明显降低，不能恢复正常；(2)低剂量（10 Gy）辐照后，丙二醛（MDA）含量显著上升，8 h后出现回落，到24~48 h时，回升至正常水平，较低剂量（20 Gy）辐照后，MDA含量瞬时有所下降，到24~48 h时，回升至正常水平，中等至高剂量（40~80 Gy）辐照后，MDA含量降低，24~48 h时显著升高，不能恢复正常；(3)低剂量（10 Gy）辐照后，超氧化物歧化酶（SOD）活性显著上升，8 h后出现回落，恢复正常，中等剂量（20~60 Gy）辐照后，SOD活性显著上升，到48 h时回落至正常水平，高剂量（80 Gy）辐照后，SOD活性无明显上升，到48 h时，活性明显降低，不能恢复正常。

Effect of Irradiation of Carbon Ions Beam on the Photosynthetic Pigments and Oxidative Activity of Scenedesmus quadricauda

Chlorophyll a, chlorophyll b, carotenoid, superoxide dismutase (SOD) and malondialdehyde (MDA) of Scenedesmus quadricauda were measured to study the injury mechanism of different doses (10-80 Gy) after irradiation by 80 MeV/u ¹²C⁶⁺ of Heavy Ion Research Facility (HIRFL, Lanzhou, China). The obtained results were as follows: 1) Chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoid were measured in different culture times after irradiation. For low-dose groups (10-20 Gy), contents of Chla, Chlb and carotenoid decreased slightly or did not vary significantly; for middle-dose groups (40-60 Gy), contents of Chl a, Chl b and carotenoid increased apparently, and then went down to the level of control group; for high dose group (80 Gy), contents of Chl a, Chl b and carotenoid were impacted severely and did not show sign of recovery. 2) Malonaldehyde (MDA) was measured in different culture times after irradiation. For low-dose group (10 Gy), the injury of membrane lipid appeared immediately after irradiation, it became lighten after 8 h, and then recovered to the level of control group within 24-48 h; for the 20 Gy group, the content of MDA decreased immediately, and then came back to the normal level; for middle and high-dose groups (40-80 Gy), the injury of membrane lipid did not happen instantly, while it became obviously in 24-48 h, and did not has the ability of recovery to the normal level. 3) Superoxide dismutase (SOD) was measured in different culture times after irradiation. For low-dose group (10 Gy), the activity of SOD rose significantly, and then declined to the normal level in 8 h; for middle-dose groups (20-60 Gy), the activity of SOD ascended markedly and went back to the normal within 48 h; for high-dose group (80 Gy), the activity of SOD did not has a sign of increment, while it descended obviously and did not recover to the normal within 48 h.