【作者】 谢作明；

【导师】 刘永定；

【作者基本信息】 中国科学院研究生院（水生生物研究所） ， 环境科学， 2006， 博士

【摘要】 以爪哇伪枝藻(Scytonema javanicum (Kütz.) Born et Flah)、具鞘微鞘藻(Microcoleus vaginatus Gom.)和纤细席藻(Phormidium tenue (Menegh.) Gom.)为材料,研究了前两种荒漠藻在紫外线(UV)辐射下的形态和超微结构、生理生化特性的变化以及它们消除因UV辐射所导致的氧化胁迫的机理;还对三种荒漠藻规模化培养条件进行了优化,并对它们藻结皮的培植与发育、藻结皮发育阶段理化性质的改变等进行了细致地研究。经UV辐射后,S. javanicum细胞的直径和体积变小。在增强的UV-B辐射下,培养物变黄且生物量下降,藻细胞沉于液体培养基底部;而在UV-A辐射下,培养物浓度增加,藻细胞浮于液面。通过电镜发现,经UV辐射后,藻细胞中脂肪颗粒和多糖颗粒等与对照相比都有所增加;经UV-A处理后,藻细胞内片层结构更明显,几乎充满整个细胞;在UV-B处理后的藻细胞横切面周边区有一圈透亮小点。对S. javanicum和M. vaginatus的光合作用研究发现,在低剂量(低于0.4 mW cm-2)的UV-A处理下,S. javanicum的Fv/Fm比值开始出现下降,但随后又上升,48 h后超过对照组,总体上呈现轻微上升。而UV-A使M. vaginatus的Fv/Fm比值有很小的下降。这些说明UV-A辐射对荒漠藻的光合作用影响不大。0.48 mW cm-2的UV-B辐射处理72 h后,S. javanicum的Fv/Fm比值下降到很低水平。UV-B辐射剂量小于0.06 mW cm-2时,S. javanicum的光合放氧速率随剂量的增加而降低较缓慢;当剂量超过0.06 mW cm-2后,光合放氧速率快速降低,当剂量达到0.48 mW cm-2时,藻体的净光合速率为负值。说明较高剂量的UV-B辐射可显著抑制光合作用。UV辐射对S. javanicum和M. vaginatus的色素变化具有重要影响。UV-A促进这两种荒漠藻叶绿素a、scytonemin、类胡萝卜素和藻蓝蛋白等色素的合成。在UV-B辐射下,S. javanicum和M. vaginatus的叶绿素和藻蓝蛋白含量快速下降,0.48 mW cm-2剂量的UV-B处理96 h后,这两种色素含量已经下降到很低水平。UV-B促进保护色素伪枝藻素和其它类胡萝卜素的合成,辐射剂量越高作用越明显。UV辐射对藻细胞中可溶性蛋白质、胞内总糖和胞外多糖(EPS)的积累具更多还原

【Abstract】 Scytonema javanicum (Kütz.) Born et Flah, Microcoleus vaginatus Gom. and Phormidium tenue (Menegh.) Gom., isolated from desert microbial crusts by Dr. C.X. HU, were used as experimental materials. Effects of UV radiation on the morphology and ultrastructure of S. javanicum, and on the physiological and biochemical characteristics of S. javanicum and M. vaginatus were studied. Those that the mechanism of oxidative stress by UV-B radiation, the optimized cultivation conditions for mass culture, the implantation and development of man-made algal crust in field and physical-chemical properties of artificial algal crust were also studied. The main results were shown as the followings:After exposure to an enhanced UV-B radiation, both morphology and ultrastructure of S. javanicum changed, the diameter and volume of cells diminished, biomass decreased and population color got yellowing in the culture. The laminar structure became more visible, and increasing number of polysaccharides and fat granules were displayed.Under UV-A radiation, changes in Fv/Fm of S. javanicum had such a trend: firstly decreased, then increased even exceeded the controls in 48hrs. To M. vaginatus, the Fv/Fm had a slightly decrease. These changes suggested the photosynthesis of algae was somewhat related with UV-A radiation. Undeer 0.48更多还原