McIntyre Alexa B R, Rizzardi Lindsay, Yu Angela M, Alexander Noah, Rosen Gail L, Botkin Douglas J, Stahl Sarah E, John Kristen K, Castro-Wallace Sarah L, McGrath Ken, Burton Aaron S, Feinberg Andrew P, Mason Christopher E
Tri-Institutional Training Program in Computational Biology and Medicine, New York, NY, USA.
Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA.
NPJ Microgravity. 2016 Oct 20;2:16035. doi: 10.1038/npjmgrav.2016.35. eCollection 2016.
Rapid DNA sequencing and analysis has been a long-sought goal in remote research and point-of-care medicine. In microgravity, DNA sequencing can facilitate novel astrobiological research and close monitoring of crew health, but spaceflight places stringent restrictions on the mass and volume of instruments, crew operation time, and instrument functionality. The recent emergence of portable, nanopore-based tools with streamlined sample preparation protocols finally enables DNA sequencing on missions in microgravity. As a first step toward sequencing in space and aboard the International Space Station (ISS), we tested the Oxford Nanopore Technologies MinION during a parabolic flight to understand the effects of variable gravity on the instrument and data. In a successful proof-of-principle experiment, we found that the instrument generated DNA reads over the course of the flight, including the first ever sequenced in microgravity, and additional reads measured after the flight concluded its parabolas. Here we detail modifications to the sample-loading procedures to facilitate nanopore sequencing aboard the ISS and in other microgravity environments. We also evaluate existing analysis methods and outline two new approaches, the first based on a wave-fingerprint method and the second on entropy signal mapping. Computationally light analysis methods offer the potential for species identification, but are limited by the error profiles (stays, skips, and mismatches) of older nanopore data. Higher accuracies attainable with modified sample processing methods and the latest version of flow cells will further enable the use of nanopore sequencers for diagnostics and research in space.
快速DNA测序与分析一直是远程研究和即时医疗领域长期追求的目标。在微重力环境下,DNA测序有助于开展新的天体生物学研究并密切监测宇航员健康状况,但太空飞行对仪器的质量和体积、宇航员操作时间以及仪器功能都有严格限制。近期出现的基于纳米孔的便携式工具以及简化的样本制备方案,终于使在微重力任务中进行DNA测序成为可能。作为在太空和国际空间站(ISS)上进行测序的第一步,我们在抛物线飞行过程中测试了牛津纳米孔技术公司的MinION,以了解可变重力对仪器和数据的影响。在一次成功的原理验证实验中,我们发现该仪器在飞行过程中生成了DNA读数,包括首次在微重力环境下测序得到的读数,以及飞行抛物线结束后测得的额外读数。在此,我们详细介绍了对样本加载程序的改进,以便于在国际空间站和其他微重力环境中进行纳米孔测序。我们还评估了现有的分析方法,并概述了两种新方法,第一种基于波指纹法,第二种基于熵信号映射。计算量小的分析方法具有物种识别的潜力,但受旧纳米孔数据的错误特征(滞留、跳跃和错配)限制。改进的样本处理方法和最新版本的流动槽可实现更高的准确性,这将进一步推动纳米孔测序仪在太空诊断和研究中的应用。