Calcification by Hermatypic Corals: Regulation of the Calcium Pathway

[9415936]穆勒造礁珊瑚显示出两种钙化模式，一种发生在光照下，另一种发生在黑暗中。碳酸钙沉积在光线下更大，这一现象归因于藻类内共生生物（虫黄藻）的光合作用。有证据表明，这两种模式可能在机制和数量上有所不同。尽管有大量的研究，珊瑚钙化和虫黄藻光合作用之间的联系仍未得到解决。这种联系的重要性可以简单地说：珊瑚和它们的虫黄藻的伙伴关系是世界上现存（和大多数化石）珊瑚礁存在的主要原因。一个主要的问题是，碳酸钙基质（钙和溶解的无机二氧化碳）是否限制了钙化，如果是，在什么条件下。钙对生命系统的重要性导致了各种保守的钙调节机制，然而，很少有珊瑚研究检查这种调节。这一策略从其他生物矿化生物体和细胞生理学的许多领域的研究中获得了大量的信息基础。这种方法，加上珊瑚养殖的最新进展，有望在过去十年中几乎没有取得进展的研究领域取得实质性进展。本研究项目将重点研究珊瑚钙化是否受到骨骼形成部位（而不是海水中）钙的可用性的限制，以及可用性如何受到共生光合作用的影响。结合药理学和动力学方法，钙从海水到骨骼的途径将被区隔表征。通过膜运输系统和信使系统（即cAMP，钙调素）在室间的钙运动和调节将是中心兴趣。虽然这个基础研究问题可能是这个项目的充分理由，但也有更多实用价值的好处。珊瑚养殖的优化对珊瑚礁保护具有深远的意义。直接地，它为珊瑚繁殖提供了一种手段，以修复受损的珊瑚礁。在水族馆贸易中使用珊瑚养殖可以通过减少快速增长的野生捕捞间接帮助自然珊瑚礁。了解珊瑚钙化的光增强将允许操纵培养条件以产生具有一致物理特性的骨骼。这样的骨骼将有价值的用于骨重建，自然珊瑚已成功地使用。＊＊＊

9415936 Mueller Reef-building corals display two modes of calcification, that which occurs in the light and that taking place in the dark. Calcium carbonate deposition is greater in the light, a phenomenon attributed to the photosynthetic activity of algal endosymbionts (zooxanthellae). There is evidence that the two modes may differ in mechanism as well as quantitatively. In spite of numerous studies, the link between coral calcification and zooxanthellae photosynthesis remains unresolved. The significance of this link can be succinctly stated: the partnership of corals and their zooxanthellae is essentially responsible for the existence of the world's living (and most fossil) coral reefs. A major question is whether either of the calcium carbonate substrates, calcium and dissolved inorganic carbon dioxide, are limiting to calcification and, if so, under what conditions. The importance of calcium to living systems has led to a variety of well-conserved calcium regulatory mechanisms, however, very little coral research has examined such regulation. This strategy has a large base of information from research on other biomineralizing organisms and in many areas of cellular physiology. Such an approach, coupled with recent advances in coral culture, promises substantial progress in a research area that has made little during the past decade. This research project will focus on whether coral calcification is limited by calcium availability at the site of skeletogenesis (not in seawater) and how availability may be affected by symbiont photosynthetic activity. Using a combination of pharmacologic and kinetic approaches, the calcium pathway from seawater to skeleton will be compartmentally characterized. Calcium movement and regulation between compartments by membrane transport systems and messenger systems (i.e. cAMP, calmodulin ) will be of central interest. While this basic research question may be sufficient justification for this projec t, there are benefits of more practical value as well. Optimization of coral culture could have far reaching implications for coral reef conservation. Directly, it offers a means for propagation of corals to repair damaged reefs. Use of coral culture in the aquarium trade could indirectly help natural reefs by reducing the rapidly increasing wild harvest. Understanding the light-enhancement of coral calcification would allow manipulation of culture conditions to produce skeletons with consistent physical properties. Such skeletons would be of value for use in bone reconstruction where natural coral has been successfully employed. ***