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具鞘微鞘藻对风力胁迫和UV-B辐射的生理响应机理研究
徐娟娟
Subtype博士
Thesis Advisor胡春香
2008-06-14
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Degree Discipline水生生物学
Keyword具鞘微鞘藻 风力胁迫 失水-重吸水 Uv-b辐射
Abstract具鞘微鞘藻(Microcoleus vaginatus Gom.)是一种具有很强固沙能力的丝状蓝藻,常作为优势种第一个在流动沙丘上殖生,对荒漠裸露微环境中的风力胁迫和紫外辐射有很强的适应性。本文针对这些现象对结皮中具鞘微鞘藻的生理生态适应性进行了研究,主要结果如下: 1 风力胁迫对光合活性的影响:不论低于当地起沙风(3m/s)还是高于起沙风(5m/s和7m/s)的风力吹蚀,结皮中藻类生物量均明显下降,而且结皮生物量的变化与风速大小和吹蚀时间呈线性关系(y=14.778+0.035a-1.484b, a风速, b时间, r2= 0.786)。进一步分析发现,风力吹蚀后结皮中藻类活力并没有降低,但主要光合色素和天线色素的含量普遍降低,叶绿素荧光(Fv/Fm)、表观电子传递速率(ETR)和净光合速率(Pn)明显下降,并且风速越大,降幅越大。这些结果说明风力胁迫对藻结皮生物量和光合活性的影响主要是通过影响光合色素代谢合成和电子传递速率引起的,对其生命力没有明显影响。 2 风力胁迫对物质代谢的影响:较长时间的风力胁迫(7天)下,细胞糖含量(总糖、还原性糖、胞外多糖)、蛋白质和脯氨酸含量均随胁迫时间延长逐渐升高,天线色素中藻胆素含量呈先下降后上升趋势,类胡萝卜素则是缓慢增长,但chla含量呈下降趋势。 3 失水-重吸水对光合活性的影响:水饱和结皮在干燥过程中,PSII和净光合速率呈先上升后下降的趋势。PSII活性在91%含水量时最高,随后开始下降,并在0.62%含水量时检测不到,而净光合速率在28%含水量时最高。干燥结皮在重吸水过程中,PSII和净光合速率均呈上升趋势,并分别在43%和64%含水量时有最高值。短期干燥的结皮光合活性恢复不依赖于藻体蛋白质的重新合成;而长期干燥的结皮则依赖于蛋白质的重新合成。 4 UV-B辐射对生长和形态结构的影响:UV-B辐射使藻结皮生长明显减缓,细胞结构发生变化。随着辐射强度(50µW/cm2,100µW/cm2,150µW/cm2)的增加,胞内中心质明显固缩,光合片层数目减少,间距紧缩(由对照的64.3nm缩短到50nm,35.7nm,34.3nm),黑色颗粒增多;胞外细胞壁和胶鞘增厚。 5. UV-B辐射对光合活性的影响:随着辐射强度的增加,可变荧光产量(Fv),PSII原初光能转换效率(Fv/Fm)、PSII潜在活性(Fv/Fo)、荧光参数(T1/2)等均随辐射强度的增加而显著下降,具有明显的剂量-效应关系。 6 UV-B辐射对色素合成的影响:不同强度的辐射处理均可诱导藻体合成伪枝藻素(scytonemin)、类菌孢素氨基酸(MAAs)和类胡萝卜素等保护色素,且均呈剂量-效应关系。但低强度下伪枝藻素和类胡萝卜素的合成响应更快。 7 UV-B辐射对物质代谢的影响:低强度辐射下藻体糖含量呈增长趋势;低、中强度辐射都可使蛋白含量增加;低、中、高强度辐射均使脂类物质积累,且脂类积累与辐射强度呈线性关系。此外,MDA含量随UV-B辐射强度和处理时间的延长而逐渐升高,抗氧化酶系统也有相应的应答反应。
Other AbstractMicrocoleus vaginatus Gom. is a filament cyanobacterium with strong cohesion in stabilization sand surface. It often firstly occurs on the surface of sand dune as dominant species or community-buliding species, with well adaptation to many desert stress environments like wind stress and ultraviolet radiation. In this paper, the physiological responses of M. vaginatus within crusts against wind force and UV-B were studied. The main results are as follows: 1 Effects of wind stress on photosynthetic activity It was discovered that alga biomass decreased significantly in different intensity of wind blowing corrosion. And the biomass of crust was affected significantly by wind speed and wind blowing time, and the linear regression formula was y=14.778+0.035a-1.484b,r2=0.786 (a is wind speed, b is windy time). Furthermore, the cell vitality did not decrease, but the main photosynthetic pigments and antenna pigment contents did. Chlorophyll fluorescence (Fv/Fm), the apparent electron transfer rate (ETR) and net photosynthetic rate (Pn) decreased significantly, and the higher the wind speed, the more the drop. These results indicated that wind stress affected the biomass and photosynthetic activity of algal crust by changing the pigments anabolism and interfering the photosynthetic electron transport rate, but algal cell vitality was not affected obviously. 2. Effects of long-term wind stress on substance metabolism Carbohydrate contents (total sugar, reducing sugar, extracellular polysaccharide) and protein contents and proline contents gradually increased under the long-term wind froce. Phycobilin decreased at first, then increased. And carotenoid increased gradually, while the content of chlorophyll a decreased all the time. 3 Effects of dehydration and rehydration on photosynthetic activity During the dehydration process of M.vaginatus crusts with saturated water, photosystem II activity and the net photosynthetic rate increased at the first stage, decreased at the later stage. The PSII activity reached to the maximum value at 91% water content, then gradually decreased till no detection at 0.62 % water content. But the net photosynthetic rate had the peak at 28% water content. During rehydration process, the activity of PSII and the net photosynthetic rate all increased, and had the maximum value respectively at 43% and 64% water content. The recovery of photosynthetic activity for short-time desiccation crust wasnt dependent on the de novo synthesis of protein, but long-time desiccation crust did. 4. Effects of UV-B radiation on the growth of alga and cell structure UV-B radiation showed a negative effect on the growth of M.vaginatus, it also caused an evident change in the cell ultrastructure. With the increase of radiation intensities (50µW/cm2, 100µW/cm2, 150µW/cm2), intracellular central body condensed distinctly, photosynthetic laminar structure shrinked (from 64.3nm of the control group to 50nm, 35.7nm, 34.3nm respectively), and the number of black granules increased. Also, cell wall and sheath got thicker. 5. Effect of UV-B radiation on the photosynthetic activity With the increase of UV-B radiation intensities, variable fluorescence (Fv), primary energy conversion efficiency (Fv/Fm), potential activity of PSII, fluorescence parameter (T1/2) of M.vaginatus crusts all decreased significantly, and with a dose-effect relationship. 6. Effects of UV-B radiation on the synthesis of pigments Different UV-B radiation intensities all induced the synthesis of scytonemin, MAAs and carotenoid, and showed the dose - effect relationship. But under the low intensity radiation, the synthesis responses of scytonemin and carotenoid were more sensitively. 7. Effects of UV-B radiation on the substance metabolism Exposed to different intensity radiation, the carbohydrate content of M. vainatus crusts showed an increase trend only in low radiation intensity, the protein contents increased in both low and medium intensity, while the lipid accumulated in all intensity, and with a dose- dependent relationship. In addition, lipid-peroxidation, a main manifestation of oxidative damage, was studied, the increase in malondiadehyde was observed. And the corresponding responses in antioxidant enzyme system were discovered as well.
Pages87
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12334
Collection学位论文
Recommended Citation
GB/T 7714
徐娟娟. 具鞘微鞘藻对风力胁迫和UV-B辐射的生理响应机理研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2008.
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