碳离子辐照对四尾栅藻光合色素及抗氧化活性的影响

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

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（10～80Gy）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（Chla）、叶绿素b（Chlb）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（10～20Gy）辐照后，光合色素含量变化较小或无显著变化，中等剂量（40—60Gy）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（80Gy）辐照后，光合色素含量明显降低，不能恢复正常；（2）低剂量（10Gy）辐照后，丙二醛（MDA）含量显著上升，8h后出现回落，到24—48h时，回升至正常水平，较低剂量（20Gy）辐照后，MDA含量瞬时有所下降，到24—48h时，回升至正常水平，中等至高剂量（40—80Gy）辐照后，MDA含量降低，24～48h时显著升高，不能恢复正常；（3）低剂量（10Gy）辐照后，超氧化物歧化酶（SOD）活性显著上升，8h后出现回落，恢复正常，中等剂量（20～60Gy）辐照后，SOD活性显著上升，到48h时回落至正常水平，高剂量（80Gy）辐照后，SOD活性无明显上升，到48h时，活性明显降低，不能恢复正常。

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 MIJA 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.