International Research Fellowship Program: The Effects of Increased Temperature and pCO2 on the Molecular Physiology of the Reef-Building Coral Seriatopora Hystrix

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。国际研究奖学金项目使美国科学家和工程师能够在国外进行9至24个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。​此外，大气二氧化碳分压的升高可能导致海洋酸化（OA）的急剧增加，珊瑚可能不再积聚构成珊瑚礁结构基础的CaCO3骨架。因此，有必要在细胞和分子水平上研究GCC对这些共生的影响。​（aC高于夏季平均温度）和二氧化碳分压（500ppm），并在数月至数年的时间尺度上观察其影响。珊瑚及其内共生鞭毛藻（共生属）可能通过调节其代谢对话来适应温度升高和OA，从而导致整合共生关系的渗透调节策略的变化。因此，使用扫描电子和共聚焦显微镜监测细胞体积和结构的变化，因为NMMBA是使用最先进的显微镜研究这些共生细胞生物学的首选场所。与此同时，每隔一个月从实验珊瑚中分离出RNA、DNA和蛋白质，在加州大学圣巴巴拉分校格雷琴·霍夫曼教授的实验室进行基因组和蛋白质组学分析。具体地说，cDNA微阵列正被用于研究基因水平的响应。采用实时荧光定量PCR和Western blots串联检测，分别证实了基因和蛋白表达的变化。在这些条件下，参与建立渗透稳态的基因/蛋白质在短期内可能会发生剧烈的表达变化，但最终，在数月至数年的高温和二氧化碳分压暴露后，可能会产生适应反应，从而在居住内共生鞭毛藻的珊瑚细胞内重新建立渗透和代谢平衡。这些实验的目的是展示珊瑚对GCC的反应，并揭示适应的潜在机制，希望更好地了解珊瑚的应激反应，从而开发出评估珊瑚礁健康的分子生物标志物系统。通过使用分子特征（即候选基因/蛋白质的差异表达）来诊断生态上重要的造礁珊瑚的健康状况，最终可以采用一种主动监测珊瑚礁健康的手段，从而通过立法和适应性管理，在大规模死亡事件发生之前，通过减轻更容易减轻的更严重的人为压力，对受威胁的珊瑚礁进行保护。

0852960MayfieldThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Anderson B. Mayfield to work with Dr. Chii-Shiarng Chen at the National Museum of Marine Biology and Aquarium in Taiwan, and with Dr. Gretchen Hofmann at the University of California, Santa Barbara in the U.S.The most significant threat to coral reef ecosystems is global climate change (GCC), as prolonged increases in ocean temperature cause the coral-dinoflagellate symbioses that form coral reefs to break down. Furthermore, elevation of atmospheric pCO2 could result in such dramatic increases in ocean acidification (OA) that corals may no longer accrete the CaCO3 skeletons that form the structural foundation of reefs. Thus, there is a need to study the impacts of GCC on these symbioses at cell and molecular levels. With temperature and CO2-controlled mesocosms housed at Taiwan¡¦s National Museum of Marine Biology and Aquarium (NMMBA), the ability of the reef-building coral Seriatopora hystrix to acclimate to temperature and CO2 regimes which will mimic the expected conditions of Taiwanese reefs in 2050 is being assessed by exposing colonies to elevated temperature (2?aC higher than average summer temperatures) and pCO2 (500 ppm) and observing the effects over a months-years timescale. Corals and their endosymbiotic dinoflagellates (genus Symbiodinium) may acclimatize to increasing temperatures and OA by adjusting their metabolic dialogue, leading to changes in the osmoregulatory strategies which integrate the symbiosis. Therefore, alterations in cell volume and architecture are being monitored with scanning electron and confocal microscopy, as NMMBA is the premier venue for studying the cell biology of these symbioses using state of the art microscopes. In parallel, RNA, DNA, and protein are isolated from the experimental corals at monthly intervals for genomic and proteomic analyses carried out in the laboratory of Prof. Gretchen Hofmann at the University of California, Santa Barbara. Specifically, cDNA microarrays are being employed to study the gene level response of. S. hystrix to GCC with quantitative real-time PCR and Western blots used in tandem to confirm changes in gene and protein expression, respectively. Genes/proteins involved in establishment of osmotic homeostasis may undergo dramatic changes in expression in response to these conditions in the short term, though ultimately, after months to years of exposure to higher temperature and pCO2, an acclimation response will likely be mounted such that osmotic and metabolic balance are re-established within coral cells housing endosymbiotic dinoflagellates. The goals of these experiments are to show how corals will respond to GCC and unveil potential mechanisms of acclimatization with the hope that a better understanding of the coral stress response will lead to development of a molecular biomarker system for assessing coral reef health. By using molecular signatures (i.e., differential expression of candidate genes/proteins) to diagnose the health of ecologically important reef-building corals, a proactive means of monitoring reef health could ultimately be employed such that threatened reefs can be targeted for protection via legislation and adaptive management before episodes of mass mortality occur by alleviating the more acute anthropogenic pressures that can more readily be mitigated.