The Role of the Epigenetic Mechanism, DNA Methylation, in the Tolerance and Resistance of Antarctic Pteropods to Ocean Acidification and Warming

第一部分：非技术描述：在极地项目办公室的支持下，该项目将评估南极洲沿海海洋食物网的重要组成部分将如何应对气候变化。浮游生物的重点研究生物是一种有壳软体动物，南极翼足类，Limacina helicina antarctica，一种已知对气候驱动的海洋酸化和海洋变暖变化做出反应的南大洋生物。海洋酸化，即通过吸收海洋表面大气中的二氧化碳而降低海洋pH值，是海洋的一种变化，预计在几十年内将超过有害的pH值阈值。这项研究将提高对翼足类动物如何应对的理解，这将为预测南极海洋生态系统在未来变化中的恢复力提供洞见，这是地球上最后的海洋荒野之一。该项目将使用分子生物学的工具来具体研究翼足类动物的基因表达是如何被调节的，以及基因的变化和调节是如何抵抗低pH和高温的压力的。此外，该项目还支持博士研究生的培养，特别是在STEM和海洋科学领域实现包容性卓越的目标。参与该项目的学生来自传统上在海洋科学领域代表性不足的群体，包括第一代大学生。总体而言，该项目有助于美国劳动力的发展，并有助于地球科学的多样性和包容性卓越。第二部分：技术描述：本项目的总体目标是研究南极翼足类动物对海洋酸化（OA）和海洋变暖的分子响应。该项目将通过评估DNA甲基化在三种环境条件下的动态变化，研究南极冰原幼鱼表观基因组的变化。三种环境条件分别是：(1)目前夏季和冬季的二氧化碳分压条件，(2)未来10-15年内预计的海洋酸化，以及(3)多应激源实验，研究OA和高温胁迫的协同相互作用。最近基于实验室的中观实验研究表明，翼足类基因组的整体DNA甲基化动态发生了显著变化，同时基因表达也发生了变化，以响应非生物变化。因此，很明显，幼年南极l.h.能够对海洋酸化作出实质性的表观遗传反应。然而，作为一种表观遗传过程，DNA甲基化如何调节转录组的变化尚不清楚。为了解决翼足类动物表观遗传学知识的这一空白，该项目将使用下一代测序方法（例如RNA测序和亚硫酸氢盐还原测序）来整合幼年翼足类动物甲基化状态的变化与基因表达的变化。总之，本研究是探索南大洋大型浮游动物对人为气候变化响应的环境转录组学和表型可塑性的重要一步。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Part 1: Non-technical description: With support from the Office of Polar Programs, this project will evaluate how an important part of the food web in the coastal ocean of Antarctica will respond to climate change. The focal study organism in the plankton is a shelled mollusk, the Antarctic pteropod, Limacina helicina antarctica, an Southern Ocean organism that this known to respond to climate driven changes in ocean acidification and ocean warming. Ocean acidification, the lowering of ocean pH via the absorption of atmospheric carbon dioxide in the surface of the ocean, is a change in the ocean that is expected to cross deleterious thresholds of pH within decades. This study will improve understanding of how pteropods will respond, which will provide insight into predicting the resilience of the Antarctic marine ecosystem during future changes, one of the planet’s last marine wildernesses. The project will use tools of molecular biology to examine specifically how gene expression is modulated in the pteropods, and further, how the changes and regulation of genes act to resist the stress of low pH and high temperature. In addition, this project supports the training of Ph.D. graduate students and advances the goal of inclusive excellence in STEM and in marine sciences, in particular. The students involved in this project are from groups traditionally under-represented in marine science including first-generation college students. Overall, the project contributes to the development of the U.S. work force and contributes to diversity and inclusive excellence in the geosciences.Part 2: Technical description: The overarching goal of this project is to investigate the molecular response of the Antarctic thecosome pteropod, Limacina helicina antarctica to ocean acidification (OA) and ocean warming. The project will investigate changes in the epigenome of juvenile L. h. antarctica, by assessing the dynamics of DNA methylation in response to three scenarios of environmental conditions that were simulated in laboratory mesocosm CO2 experiments: (1) present-day pCO2 conditions for summer and winter, (2) future ocean acidification expected within 10-15 years, and (3) a multiple stressor experiment to investigate synergistic interaction of OA and high temperature stress. Recent lab-based mesocosm experiment research showed significant changes in the dynamics of global DNA methylation in the pteropod genome, along with variation in gene expression in response to abiotic changes. Thus, it is clear that juvenile L. h. antarctica are capable of mounting a substantial epigenetic response to ocean acidification. However, it is not known how DNA methylation, as an epigenetic process, is modulating changes in the transcriptome. In order to address this gap in the epigenetic knowledge regarding pteropods, the project will use next-generation sequencing approaches (e.g., RNA sequencing and reduced representation bisulfite sequencing) to integrate changes in methylation status with changes in gene expression in juvenile pteropods. Overall, this investigation is an important step in exploring environmental transcriptomics and phenotypic plasticity of an ecologically important member of Southern Ocean macrozoooplankton in response to anthropogenic climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.