UV-B短期照射对北极冰川小球藻Chlorella sp.的生物学效应

THE PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES OF AN ARCTIC MICROALGAE(CHLORELLA SP.) TO UV-B RADIATION

以一种分离自北极冰川融水的淡水微藻(Chlorella sp.)为实验材料,设置两个不同强度UV-B(45μW/cm2,76μW/cm2)照射处理,每4h取样检测,对其生化组分进行分析,了解微藻对UV-B辐射的响应。研究结果显示小球藻经辐射处理后,其生化成分发生变化:(1)在较低强度的UV-B(45μW/cm2)辐射下,叶绿素a(Chla)和类胡萝卜素(Car)含量先升后降,且在4h时有最大值;高强度UV-B(76μW/cm2)辐射下,Chla和Car含量随辐射时间延长基本呈下降趋势;(2)超氧阴离子(O2ˉ·)和丙二醛(MDA)含量基本随辐照时间的延长和辐照强度的增大而提高,过氧化氢(H2O2)含量变化虽随辐照时间的延长呈上升趋势,但直到12h才表现为明显提高;(3)超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性在低UV-B处理下,随辐照时间的延长呈升高趋势;在高UV-B辐射下,SOD活性先升后降,CAT活性上下波动;(4)UV-B辐射使小球藻脂肪酸组成发生了变化。结果表明:UV-B,尤其是高强度或较高剂量的UV-B会对北极冰川微藻带来不利的影响。

The response of an Arctic microalgae strain （ Chlorella sp. ） to the enhancement of UV-B radiation was explored in this paper. The effects of three different intensity （0 μW/cm^2, 45 μW/cm^2, 76 μW/cm^2 ） on Chorella sp. within 12 h radiation following with 4 h non-radiation recovery were studied, while the biochemical components were tested by sampling every 4 h. Our results showed that： （1） Under the lower intensity of UV-B （45 μW/cm^2） radiation, Chla and Car content increased in the beginning 4 h and then decreased. The maximum value presented after 4 h. Meanwhile, under high-intensity UV-B （76 μW/cm^2 ） radiation, Chla and CAR content constantly decreased. （2） The content of O2^-· and MDA enhanced along with radiation time and intensity. Moreover, H2O2 content also increased with irradiation time ; significant variance happened after 8 h radiation. （3） SOD, CAT activity under the lower UV-B treatment, increased with irradiation time as well. Under higher UV-B radiation, SOD activity increased at the beginning 4 h and then decreased constantly, CAT activity fluctuated from time to time. （4）The fatty acid composition of Chlorella sp. was influenced. The results supported that UV-B had adverse effects on the Arctic glacier＇s microalgae, and the effect of hurt was more significant under high-intensity or high doses of UV-B.