Biomineralization in cysts of flagellated microalgae

生物矿化是指通过生物过程形成的复杂无机物质，是一种普遍存在的现象。形成的矿物是无机/有机复合材料（生物材料），具有高度控制的宏观和纳米结构矿物相，使其具有多功能特性。生物材料的美丽例子出现在单细胞真核微藻中；提案的重点。鞭毛微藻是浮游生物的主要类群。其中，鞭毛藻是最大的种群之一，现存物种约有2000种。许多沿海物种与夏季发生的有害藻华有关。由于产生神经毒素，这些水华可能导致鱼类、贻贝和其他形式的海洋生物大量死亡。人类可能会因食用含有这些毒素的动物而中毒，这被称为麻痹性贝类中毒。由于这个原因，有一个强烈的生态兴趣，了解更多关于鞭毛藻复杂的生命周期。生命周期通常包括无性细胞分裂，但有性生殖也会发生。超过10%的鞭毛藻物种会产生（矿化）休息阶段，称为鞭毛藻囊肿，作为其生命周期的一部分。此外，一些鞭毛类的囊肿表现出有机壁或钙质壁，有时甚至是硅质壁。钙质静息囊由方解石组成，内部有机层支撑钙质纹饰。虽然鞭毛藻囊结构为古地质学家所知，但鞭毛藻的生物矿化过程尚未被研究，尽管鞭毛藻是第二丰富的钙质浮游植物群。此外，鞭毛藻是一种极有前途的生物矿化模型系统，因为它们很容易从沉积物中培养或分离出来。在培养过程中，营养物质的消耗、温度的变化和光照的改变都容易引起包囊的形成。最近，方解石囊肿化石显示出非常有趣的、交织的纤维状结构。这些非常特殊的篮状结构构成了一种新型的方解石生物矿物结构。到目前为止，这些结构仅在化石囊肿中观察到，这引起了许多关于活甲藻囊肿生物矿物形成的问题。目前还没有详细的结构/功能关系，也不知道矿物相的形成和稳定机制。因此，计划研究的目的是研究鞭毛藻在其复杂的生命周期中的生物矿化过程，特别是结构形成机制以及有机物质与矿物相，特别是碳酸钙之间的相互作用。对于新培养的矿化囊肿结构的研究，提出了使用Cryo-SEM， FIB-SEM， FT-IR和微拉曼光谱等分析方法。

Biomineralization the formation of complex inorganic materials by biological processes, is a widespread phenomenon. The minerals formed are inorganic/organic composite materials (biomaterials) with highly controlled macro- and nanostructured mineral phases that provide them with multifunctional properties. Beautiful examples of biomaterials occur in unicellular, eukaryotic microalgae; the focus of the proposal. Flagellated microalgae represent a major group of plankton. Among these, dinoflagellates with about 2000 living species constitute one of the largest groups. Many coastal species are associated with harmful algal blooms which occur in summer. Because of the production of neurotoxins these blooms may result in massive death of fish, mussels, and other forms of marine life. Humans may be poisoned by eating animals containing these toxins, what is called paralytic shellfish poisoning. For this reason there is a strong ecological interest in learning more about the complex life cycle of dinoflagellates. The life-cycle usually involves asexual cell division, but sexual reproduction also occurs. More than 10% of the dinoflagellate species produce (mineralized) resting stages, called dinoflagellate cysts, as part of their life cycle. Furthermore cysts of several dinoflagellate species exhibit organic walls or calcareous and sometimes even siliceous walls. Calcareous resting cysts are composed of calcite and an inner organic layer supports the calcareous ornamentation.Although dinoflagellate cyst structures are known to paleogeologists, the biomineralization processes in dinoflagellates have not been investigated despite the fact that dinoflagellates are the second most abundant calcareous phytoplankton group. Furthermore, dinoflagellates are an extremely promising model system for biomineralization since they can easily be cultivated or isolated from sediments. Cyst formation be easily induced in culture by nutrient depletion or change of temperature and light irradiation. Recently, fossilized calcite-cysts were shown to have extremely interesting, interwoven fibre-like structures. These very special, basket-like structures constitutes a novel type of calcite biomineral architecture. These structures so far observed only in fossil cysts raises numerous questions concerning biomineral formation in living dinoflagellate cysts. At the moment, neither the detailed structure/function relations, nor the formation and stabilization mechanism of the mineral phase are known. The aim of the planned research is therefore, to investigate the biomineralization processes in dinoflagellates during their complex life cycle, especially the structure formation mechanisms and the interactions between the organic material and the mineral phase, particularly the calcium carbonate. For the study of freshly cultured mineralized cyst structures the use of analytical methods like Cryo-SEM, FIB-SEM, FT-IR and Micro-Raman spectroscopy is proposed.