EAPSI: Do Symbiodinium Exhibit Species-specific Responses to Iron Availability?

在共生藻属中，造礁珊瑚和它们的光合共生体之间的互惠共生构成了许多浅水热带海洋生态系统的基础。与气候变化有关的严重海洋变暖事件导致许多热带和亚热带地区的珊瑚数量大规模下降。虽然许多共生体容易受到热应激的影响，但各种物种和群体在视觉上似乎没有受到影响，这促使许多研究了解解释这种抗性的潜在生物学属性。共生生物和寄主珊瑚的持久和生长需要微量金属，这些金属对光合作用和氮同化等重要过程是必不可少的。以前的研究表明，痕量金属的可用性，尤其是铁，会影响海洋浮游植物的生长，并有助于应对压力。微量金属的可获得性影响共生珊瑚对热应激的抵抗力的可能性目前尚不清楚。主办方科学家何东元博士(台湾中央研究院)最近描述了共生菌生长对痕量金属的需求，发现铁的可利用性增加与藻类的生长呈正相关。在这项研究的基础上，这个项目将在这项研究的基础上，通过评估远距离和密切相关的共生生物物种对铁的需求，并利用我对何博士的痕量金属清洁实验室的访问。了解不同种类共生藻对铁的需求将为未来研究铁的可获得性和随后的获取是否影响共生珊瑚在热胁迫期间的共生奠定基础。在这次实验中，10种共生菌将在环境条件下生长，并暴露在不同微量铁浓度下。生长率将被量化，并使用细胞密度进行比较。为了确定共生线虫对铁的需求，在生长实验过程中，将使用多个点的元素分析来量化细胞铁水平。研究微量铁的可获得性如何改变众多共生生物物种的生长动力学，将确定铁的需求是否遵循系统发育模式，并在适应冷热水的共生生物中是独一无二的。该奖项由东亚和太平洋夏季研究所计划设立，支持一名美国研究生的夏季研究，并由美国国家科学基金会和台湾科技部联合资助。

The mutualistic symbiosis between reef-building corals and their photosynthetic symbionts in the genus Symbiodinium form the basis of many shallow water tropical marine ecosystems. Episodes of severe ocean warming linked to climate change has driven largescale declines of coral populations in many tropical and subtropical regions. While many symbioses are susceptible to heat stress, various species and colonies appear unaffected visually, spurring many investigations into learning the underlying biological attributes that explain this resistance. The persistence and growth of Symbiodinium and host coral requires trace metals which are essential to vital processes such as photosynthesis and nitrogen assimilation. Previous studies have shown that the availability of trace metals, most notably iron, influences marine phytoplankton growth and assists in stress responses. The possibility that trace metal availability affects resistance to thermal stress in symbiotic corals is currently unexplored. The host scientist, Dr. Tung-Yuan Ho (Academia Sinica, Taiwan) recently described the trace metal requirements for growth by Symbiodinium kawagutii finding that increased iron availability was positively correlated with algal growth. To build upon this study, this project will expand upon this study by evaluating iron requirements among distantly and closely-related species of Symbiodinium and capitalize upon my access to Dr. Ho's trace metal clean laboratory. Knowledge of iron requirements for a diversity of Symbiodinium species (in culture) will lay the foundation for future investigation on whether the availability and subsequent acquisition of iron affects corals in symbiosis during periods of thermal stress.During this experiment, ten species of Symbiodinium will be grown in ambient conditions and exposed to various trace iron concentrations. Growth rates will be quantified and compared using cell density. To determine the iron requirement of Symbiodinium spp., cellular iron levels will be quantified using elemental analysis at multiple points during the growth experiment. Examining how trace iron availability alters the growth kinetics of numerous Symbiodinium species will determine whether iron requirements follow phylogenetic patterns and are unique in hot- and cold-water adapted Symbiodinium spp.This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Ministry of Science and Technology of Taiwan.