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

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。国际研究奖学金计划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。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持Anderson B.Mayfield博士与台湾国家海洋生物和水族馆的Chii-Shiarng Chen博士以及美国加州大学圣巴巴拉分校的Gretchen Hofmann博士开展的为期24个月的研究奖学金。珊瑚礁生态系统面临的最大威胁是全球气候变化(GCC)，因为海洋温度的长期上升导致形成珊瑚礁的珊瑚-甲藻共生生物分解。此外，大气中二氧化碳浓度的升高可能会导致海洋酸化(OA)的急剧增加，以至于珊瑚可能不再附着构成珊瑚礁结构基础的CaCO3骨架。因此，有必要从细胞和分子水平上研究GCC对这些共生体的影响。台湾S国家海洋生物与水族馆(NMMBA)设有温度和二氧化碳控制的中胚层，建造珊瑚礁的Seriatopora hystrix适应温度和二氧化碳状况的能力将模拟2050年台湾珊瑚礁的预期条件，正在通过将群落暴露在高温(高于夏季平均温度2℃)和二氧化碳(500ppm)中并观察其在数月至数年的时间尺度上的影响来评估。珊瑚和它们的内生共生甲藻(共生属)可能通过调节它们的代谢对话来适应不断上升的温度和OA，导致整合共生的渗透调节策略的变化。因此，扫描电子显微镜和共聚焦显微镜正在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体的细胞生物学的主要场所。同时，每月从实验珊瑚中提取RNA、DNA和蛋白质，供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分析。具体地说，基因芯片被用来研究基因水平的反应。用实时定量聚合酶链式反应和免疫印迹技术分别证实基因和蛋白表达的变化。在短期内，参与建立渗透平衡的基因/蛋白质可能会在表达上发生巨大的变化，以响应这些条件，尽管最终，在几个月到几年的更高温度和二氧化碳暴露后，可能会建立适应反应，以便在含有内共生甲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，并揭示潜在的适应机制，希望更好地了解珊瑚应激反应将导致开发用于评估珊瑚礁健康的分子生物标记系统。通过使用分子特征(即候选基因/蛋白质的差异表达)来诊断具有重要生态意义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，以便在发生大规模死亡事件之前，通过立法和适应性管理，针对受到威胁的珊瑚礁进行保护，以减轻更容易缓解的更严重的人为压力。

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.