杜氏藻Dunaliella peircei超微结构研究

两类糖蛋白纤维构成了Dunaliella peirces的细胞外被,鞭毛和基本分别为“9+2”和“9+0”结构,首次发现的中心粒由9个三联体组成,高尔基体1～2个,眼点位于细胞质中,由二排椭圆形小球构成,内质网丰富,线粒体形状多样,在“杯形”叶绿体中发现了雏形的基粒及“杯”上的小孔,叶绿体前端凹凸不平,后端具大型淀粉核一个,细胞核位于“杯形”叶绿体的凹窝中。

The effects of enriched C0_(2) and enhanced UV-B radiation on ultrastructure of Dunaliella salina, singly and in combination

The effects of ambient CO2/ambient UV-B, enriched CO2/ambient UV-B, ambient CO2/enhanced UV-B, and enriched CO2/enhanced UV-B on the ultrastructure of Dunaliella salina were investigated. （1） The ultrastructure of D..salina cell in the control experiment showed that the arrangement of thylakoid lamellae was regular, and there were many large starch grains among the thylakoid lamellae. A prominent well-developed pyrenoid was found in the middle of the chloroplast. Nucleus envelope and nucleolus were clearly observed. The Golgi apparatus accompanied by numerous vesicles with a compact arrangement of cisternae and the peripheral tips of the cisternae were swollen to a size comparable to that of some of the associated vesicles. （2） The ultrastructure of D. salina cell in enriched CO2 showed that the arrangement of thylakoid was regular and the lamellae were vivid. Developed pyrenoids were found in the low-CO2-grown cells, but not in the high-CO2-grown cells. The mitochondria cristae were vivid. The arrangement of Golgi apparatus was compact. （3） The ultrastructure of D. salina cell in enhanced UV-B showed that the thylakoid was dissolved and the cells had a less developed pyrenoid or no detectable pyrenoid. Part of the nucleus envelope was dissolved. The number ofmitochondria was increased and some mitochondria cristae were disintegrated. The starch grains were broken apart into many small starch grains. The Golgi apparatus with a loose arrangement ofcistemae and the peripheral tips of the Golgi cistemae were not especially swollen, with several large associated vesicles. （4） The ultrastructure of D. salina cell in the enriched CO2/enhanced UV-B showed that part of the thylakoid and nucleus envelopes of some cells were dissolved. The pyrenoid was larger than that of the enhanced UV-B. There were many mitochondria between stroma and chloroplast membrane, but mitochondria cristae were partly dissolved. Many small starch grains were accumulated in cells. The starch sheath was broken into several discontinuous starch grains with different sizes. The arrangement of Golgi apparatus was loose. Above all, although the enriched CO2 can alleviate the damage induced by the UV-B radiation, the effects of experimental UV-B radiation were larger than the effects of actual UV-B radiation, the damage induced by the UV-B radiation was so severe, therefore, CO2 enrichment could not restore the ultrastructure to the control level.

盐度对盐生杜氏藻叶绿体超微结构的影响

研究不同盐度对盐生杜氏藻（ Ｄｕｎａｌｉｅｌｌａｓａｌｉｎａ（ Ｄｕｎａｌ．） Ｔｅｏｄ ．） 叶绿体超微结构的影响．结果显示，在ＮａＣｌ 浓度为２ ．７ ｍｏｌ／Ｌ 的培养液中，其叶绿体为典型的杯状结构．在ＮａＣｌ 浓度从２ ．７ ｍｏｌ／Ｌ 增加到４ ．３ ｍｏｌ／Ｌ时，其杯状叶绿体逐渐离解为多个相互连结或分离的部分；叶绿体内的类囊体片层系统解体并出现大量的嗜锇质体小球；在分离的叶绿体间隙中形成多个线粒体．在培养液的ＮａＣｌ 浓度逐步从４ ．３ ｍｏｌ／Ｌ 降低到２ ．７ ｍｏｌ／Ｌ后，盐藻的叶绿体又逐步恢复为典型的杯状结构．由此可知，不同盐度下盐藻叶绿体的结构变化是一个可逆的过程，这种可逆变化是盐藻得以在高盐度，强光照，易蒸发的自然环境中生存的一种适应机制．

氧化石墨烯对2种海洋微藻的毒性效应研究

氧化石墨烯(GO)是一种具有独特电学、热学和力学性能的新型纳米材料。随着GO在工业上的广泛应用,其通过随意排放或不适当处理而进入海洋环境的数量将不断增加,因此,评估这种纳米材料对海洋生物的潜在毒性十分必要。本研究将2种海洋微藻——盐生杜氏藻(Dunaliella salina)和海洋微拟球藻(Nannochloropsis oceanic)暴露于含GO的F/2培养基中,根据其生长、细胞形态、超微结构、光合色素、抗氧化防御系统和脂质过氧化对GO的毒性效应进行评价。结果表明,GO对2种微藻具有不同毒性,72 h EC50值分别为13.04和79.10 mg·L-1。GO纳米片层既能通过吸附直接与藻细胞表面作用,也能侵入藻细胞内部,造成2种微藻的细胞形态畸变和淀粉粒积累量增加,无细胞壁的盐生杜氏藻还出现细胞膜破损、内容物外泄、细胞核皱缩、核膜模糊不清、核质凝聚等异常现象。GO对光合色素合成具有促进作用而非抑制作用,这与细胞中淀粉的积累相一致。GO暴露引起藻细胞谷胱甘肽抗氧化系统的明显变化,包括GSH大量消耗、GPx活性受抑、GST和GR活性上扬。高浓度(100 mg·L-1)GO胁迫下细胞内MDA含量激增,表明脂质过氧化严重,而盐生杜氏藻更为明显。总之,海洋微藻对GO的敏感性与其是否存在细胞壁及其抗氧化能力有关。

杜氏藻与大肠杆菌跨界融合初探

以链霉蛋白酶制得了杜氏藻(嗜盐单胞绿藻)的原生质体。采用聚乙二醇(PEG)-钙离子法将它们与大肠杆菌(含氯霉素乙酰转移酶基因质粒)的球1,20,1状体进行融合。“融合子”酷似杜氏藻。它们对氯霉素抗性的显著提高寓示了大肠杆菌的质粒已转移到“融合子”细胞中;而且,“融合子”的蛋白质组分与杜氏藻和大肠杆菌相比已发生了较明显的变化。