Over the past decade, cryogenic electron microscopy (cryo-EM) has emerged as a primary method for determining near-native, near-atomic resolution 3D structures of biological macromolecules. In order to meet increasing demand for cryo-EM, automated methods to improve throughput and efficiency while lowering costs are needed. Currently, the process of collecting high-magnification cryo-EM micrographs, data collection, requires human input and manual tuning of parameters, as expert operators must navigate low- and medium-magnification images to find good high-magnification collection locations. Automating this is non-trivial: the images suffer from low signal-to-noise ratio and are affected by a range of experimental parameters that can differ for each collection session. Here, we use various computer vision algorithms, including mixture models, convolutional neural networks (CNNs), and U-Nets to develop the first pipeline to automate low- and medium-magnification targeting with purpose-built algorithms. Learned models in this pipeline are trained on a large internal dataset of images from real world cryo-EM data collection sessions, labeled with locations that were selected by operators. Using these models, we show that we can effectively detect and classify regions of interest (ROIs) in low- and medium-magnification images, and can generalize to unseen sessions, as well as to images captured using different microscopes from external facilities. We expect our pipeline, Ptolemy, will be both immediately useful as a tool for automation of cryo-EM data collection, and serve as a foundation for future advanced methods for efficient and automated cryo-EM microscopy.
翻译:过去十年来,低温电子显微镜(cryo-EM)已成为确定生物宏观分子的近亲和近原子分辨率3D结构的主要方法。为了满足对冷冻-EM的日益增长的需求,需要采用自动化方法提高输送量和效率,同时降低成本。目前,收集高放大冷冻-EM显微镜、数据收集的过程需要人的投入和人工调整参数,因为专家操作员必须浏览低度和中度放大图像,以找到高放大度收集地点。自动化是非三维的:图像受到低信号-噪音比率的影响,并受到一系列实验参数的影响,而每次收集会议都可能有所不同。这里,我们使用各种计算机视觉算法,包括混合模型、革命性神经神经网络(CNNs)和U-Net来开发第一管道,以便以低度和中度放大为对象,用目的建立算法来自动放大低度的中度放大图像。这个管道的模型是用大型内部数据集来训练的,用我们所选的内置图像集成的内置的内置的内置图象集,作为我们所选的内置的内置的内置的内置图集,作为我们所选的内置的内置的内置的内置的内置的内置的内置的内置的内置图解工具,以便用来用来进行检索的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内存的内存,作为工具,作为我们用来用来用来用来用来用来收集的内存的内置的内置的内置的内置的内置的内置的内置的内置的内存的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内置的内存的内置的内存的内存的内存,