- 學位論文
由生物體內碳循環探討生物鈣化的促進
Investigating the carbon cycle of individual calcifying organism for enhancing biocalcification
摘要
地球碳循環中碳以不同的型式傳遞於儲存槽間，以進行能量傳遞或酸鹼平衡。海洋為地表上最大的碳儲存槽，大氣二氧化碳濃度增高時，海水中碳酸根離子轉成氫碳酸根使海水不致變酸。其實每一生物體內都有個小型的碳循環，也負責酸鹼平衡。生物的酵素只能在很窄的pH範圍內工作，保持酸鹼平衡是很重要的。本研究的構想就是要從生物體內的碳循環來檢視碳儲存槽的構造，以便對促進生物鈣化貢獻。研究以貝類為對象，它們在海洋碳循環中負責將氫碳酸根轉回碳酸根，然後以碳酸鈣方式儲存。 觀察收集到的樣品可以知道貝殼內的碳酸鈣儲存是會變動的，而生物製造的有機物可以控制碳酸鈣的結晶。例如在貝殼中含有碳酸酐酶，其主要作用就是加速碳的轉換。有機物層的結構也會因環境條件而異，原本已適應某種環境條件的有機層，可能在環境條件突然改變時失去效用。近海區域海水的鹼度因石化燃料燃燒及汙染已明顯下降，這對鈣化生物造成的影響是我們要探討的方向，鹼度代表酸鹼緩衝能力。
並列摘要
Carbon changes into different forms as it move in a carbon cycle to accomplish energy transfer or acid-base balance. The ocean, containing three forms of dissolved inorganic carbon, is noted for its great ability to absorb atmospheric carbon dioxide. As CO2 level increases, carbonate changes to bicarbonate to stabilize water pH water. In fact, most living organisms have a carbon cycle performing similar tasks. Since enzyme can only work in a very narrow range of pH value, maintaining constant pH is a housekeeping task.The current work is to study the miniature carbon cycle within shellfish to learn methods for enhancing biocalcification. Shellfish and many calcifying organisms play a crucial role in converting bicarbonate back to carbonate. The structure of shells reveals that the calcium carbonate storage is dynamic and is controlled by organic matrix. Enzyme like carbonic anhydrase is necessary to speed up the process of carbon conversion. Interestingly, organic matrix often appears to be acclimated to a specific environmental condition. As a result, some originally healthy organisms may be very vulnerable to changing environment. Severe change of environmental conditions is expect to occur more often as ocean’s buffering ability, measured as alkalinity, has greatly reduced due to fossil fuel burning and pollution.