SGER: Developing Metal-Tagged DNA Probes for High Resolution Imaging of Microbial Phylotype Distributions and Nanoscale Mineral/Microbe Associations in Environmental Samples

摘要高分辨率电子显微镜（EM）图像可以极大地放大微生物及其微生境，揭示微生物细胞及其物质环境的细微特征。EM图像在研究微生物如何与天然和人造材料相互作用方面可能有很大的用途。 然而，共存于天然样品中的许多类型的微生物通常不能仅基于外观来彼此区分。 此外，当“缩小”时，不可能看到EM安装的样品中微生物的总体分布。 必须发明一种在视觉上区分EM图像中微生物的特定遗传类型的方法，以充分利用电子显微镜的潜力，用于了解环境中原位微生物的分布和活动。 已向教授颁发了一笔赠款。瑞秋·M圣巴巴拉的加州大学的Haymon和Patricia霍尔顿，以及伍兹霍尔海洋研究所的Stefan Sievert博士，他们开发了金属“标签”，可以附着在选定的微生物的DNA序列上。 当金属被用于产生EM图像的电子束激发时，金属将发射X射线，并允许在高和低放大倍数下对目标生物体进行明确的视觉识别。 这种方法将解决现有的问题，区分空间分布和身份的微生物与电子束成像，并将有可能了解微生物和矿物的关联在小尺度上，是相关的微生物生命。拟议的金属标记的DNA探针，了解微生物如何与环境相互作用的应用是巨大的。预计该方法将成为研究自然环境中微生物活动的功能，生态和环境影响的标准工具。 例如，Haymon，霍尔顿和Sievert博士希望将这种新技术应用于土壤中微生物的研究，在土壤中微生物对有毒人为化合物的生物降解很重要，在热液系统中，微生物在极端的热和化学条件下与地质材料相互作用。

ABSTRACTHigh-resolution electron microscope (EM) images greatly magnify microbes and their microhabitats, and reveal minute features of microbial cells and their material surroundings. EM images potentially are of great use in studying how microbes interact with natural and man-made materials. However, the many types of microorganisms co-existing in natural samples typically cannot be distinguished from one another based on appearance alone. Furthermore, when "zoomed out" it is not possible to see the overall distribution of microbes in EM-mounted samples. A means of visually distinguishing specific genetic types of microbes in EM images must be invented to fully exploit the potential of electron microscopy for learning about in situ microbial distribution and activity in the environment. A grant has been awarded to Profs. Rachel M. Haymon and Patricia Holden at University of California, Santa Barbara, and to Dr. Stefan Sievert at Woods Hole Oceanographic Institution, for development of metallic "tags" that will attach to DNA sequences of selected microbes. When the metals are excited by electron beams used to generate EM images, the metals will emit X-rays and permit unambiguous visual identification of the targeted organisms at both high and low magnifications. This method will solve the existing problems in distinguishing spatial distributions and identities of microbes imaged with electron beams, and will make it possible to understand associations of microbes and minerals at small scales that are relevant to microbial life.Applications of the proposed metal-tagged DNA probes to understanding how microbes interact with the environment are vast. It is expected that the proposed method will become a standard tool for studying the function, ecology, and environmental impact of microbial activities in natural environments. For example, Drs. Haymon, Holden, and Sievert hope to apply this new technique to studies of microbes in soils, where microbes are important to biodegradation of toxic anthropogenic compounds, and in hydrothermal systems, where microbes interact with geologic materials under extreme thermal and chemical conditions.