【作者】 吴忠兴；

【导师】 宋立荣；

【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】 微囊藻是国内外水体常见的水华种类,由于某些种类能产生一种已被认为能诱发人类原发性肝癌的环状肝肽-微囊藻毒素,因此微囊藻水华产生机理及其危害引起科学界和社会各界长期和广泛的关注。在长期的进化过程中,水华蓝藻,特别是微囊藻发展了一套独特的生理学机制和适应特性,形成了极强的生态竞争优势。由于微囊藻主要以群体形式存在于微囊藻水华中,近几十年来对群体微囊藻在微囊藻水华的形成和保持中的作用已经开展了一些研究。然而,由于缺乏可比对的资料和数据,这种群体形式存在的竞争机制仍然存在较大的空白。我们实验室先前的研究表明群体和单细胞形态的微囊藻在生理适应方面有明显不同。为了进一步研究群体种群优势的机制和微囊藻的多样性,本文主要针对以下几个问题进行研究:1、群体微囊藻形成水华优势的生理基础是什么?2、在水华形成过程中,单细胞形态的微囊藻如何转化为群体形态微囊藻,这种转化的机制是什么?3、我国水体常见微囊藻水华,这些种类的亲缘关系、多样性和产毒特性如何?针对上述问题,本文开展了系统深入的研究,主要的研究结果归纳如下:1.与单细胞微囊藻相比,群体微囊藻比生长率和叶绿素含量较低,但在整个生长阶段的光合放氧、ETRmax和高效的无机碳吸收能力(K0.5DIC≤8.395±0.701μM)均较高。此外,群体微囊藻的PC在整个藻蓝蛋白组分中的百分含量明显高于单细胞微囊藻,AP∶PE的比值(1.7∶1)较单细胞微囊藻稳定;2.比较了群体和单细胞微囊藻的外源无机磷和胞外产物积累,结果表明了单细胞微囊藻的Km高于群体微囊藻,但是群体和单细胞微囊藻在Vmax/Km和Vmax并没有显著性的差异,这暗示了在形成水华过程中群体和单细胞微囊藻对磷的竞争能力大致相似,单细胞微囊藻略优于群体微囊藻。然而,群体微囊藻的胞外多糖(EPS)和总糖含量均高于单细胞微囊藻;3.群体和单细胞微囊藻的最大光合效率(Pm)和最适饱和光强(Ik)随着微囊藻群体直径大小的增加而增大。但两者的光合作用效率(α)、光补偿点(Ic)和暗呼吸(Rd)无显著的差异;4.在高光强胁迫下,微囊藻Fv/Fm、ETRmax、光合效率(α)和最适光强(Ik)都有所降低,但群体微囊藻降幅低于单细胞微囊藻;此外,群体微囊藻能通更多还原

【Abstract】 Bloom-forming cyanobacterial Microcystis has been widely reported worldwide in many freshwater bodies, mainly owing to its harmful effect, directly or indirectly, to animals and human beings. Most of Microcystis can produce microcystins, a cyclic heptapetide toxins thought to be a tumor promoter for primary liver cancer in human beings. Therefore, great attention has been focused on the formation mechanism and harmful effects of Microcystis blooms by researchers in areas such as aquatic ecology, phycology, environmental sciences and so on. As already illustrated, bloom-forming cyanobacteria, in particularly Microcystis, has developed a sound ecological strategies to form water bloom with a series of special physiological mechanisms and adaptation characters during evolution. While most of bloom of Microcysts exists as the colonial form, the role of colonial form in the formation and persistence of bloom has been investigated over the decades. Due to the lack of comparison, however, the mechanism on the role of colonial form in the competition remains largely unknown. Previous studied in our laboratory showed the differences in physiological adaptation between colonial form and single-celled form of Microcystis. To further investigate the mechanism of the role of colonial form as well as the diversity of Microcystis, this dissertation focuses on the following aspects: 1. what are advantageous physiological mechanisms of colonial Microcystis in bloom-forming? 2. how does single-celled Microcystis differentiate to colonial one during the formation of Microcystis bloom, and what are the mechanisms? 3. how are the evolution relationship, diversity and toxin profiles of Microcystis strains in water bodies of China? The main results are更多还原