Profiling the response of Arabidopsis thaliana to altered gravity environments: Exposure of the 14-3-3k:GFP overexpression line on the F-104 Starfighter, second flight

The increasing availability of flights on suborbital rockets creates new avenues for the study of spaceflight effects on biological systems, in particular the transitions between hypergravity and microgravity. This paper presents an initial comparison of the responses of Arabidopsis thaliana to suborbital and atmospheric parabolic flights as an important step toward characterizing these emerging suborbital platforms and their effects on biology. Transcriptomic profiling of the response of the Arabidopsis ecotype Wassilewskija (WS) to the aggregate spaceflight experiences in the Blue Origin New Shepard and Virgin Galactic SpaceShipTwo rockets revealed that the transcriptomic load induced by flight differed greatly between the two flights, yet was biologically related to traditional parabolic flight responses. The sku5 skewing mutant and 14-3-3κ:GFP regulatory protein overexpression lines each showed altered intra-platform responses compared to WS in the Blue Origin and parabolic flights, respectively. An additional parabolic flight using the F-104 Starfighter showed that the response of 14-3-3κ:GFP to flight was modulated in a similar manner to the WS line. Despite the differing genotypes, experimental workflows, flight profiles and platforms, alteration of gene expression remodeling central metabolic processes was commonly observed as a response to the flights. The processes included carbon and nitrogen metabolism, branched-chain amino acid degradation, and hypoxic responses. The timing and directionality of differentially-expressed genes involved in the conserved pathways differed among the platforms. The data presented herein highlight the potential for various suborbital platforms to contribute insights into biological responses to spaceflight, and further suggest that in-flight fixation during suborbital experiments will provide insights into responses to each phase of flight.

亚轨道火箭航班的日益普及，为探究太空飞行对生物系统的影响开辟了全新路径，尤其是超重力与微重力之间的过渡过程。本研究对拟南芥（Arabidopsis thaliana）在亚轨道飞行与大气抛物线飞行中的响应开展初步对比，这是表征这类新兴亚轨道平台及其生物学效应的关键一步。针对拟南芥Wassilewskija生态型（WS）在蓝色起源（Blue Origin）新谢泼德号（New Shepard）与维珍银河（Virgin Galactic）太空船二号（SpaceShipTwo）火箭的两次太空飞行的整体暴露响应进行转录组分析后发现，两次飞行诱导的转录组负荷差异显著，但在生物学层面均与传统抛物线飞行的响应相关。在蓝色起源飞行与抛物线飞行实验中，sku5倾斜突变体与14-3-3κ:绿色荧光蛋白（GFP）调控蛋白过表达株系分别相较于WS株系，展现出了改变的平台内响应特征。另一项使用F-104星式战斗机的抛物线飞行实验表明，14-3-3κ:GFP对飞行的响应调控模式与WS株系相似。尽管不同实验的基因型、实验流程、飞行剖面与平台均存在差异，但核心代谢过程的基因表达重塑变化是各类飞行响应的共同观测结果。这些核心代谢过程涵盖碳氮代谢、支链氨基酸降解以及低氧响应。参与这些保守通路的差异表达基因的时序与表达方向在不同平台间存在差异。本文呈现的数据凸显了各类亚轨道平台为太空飞行生物响应研究提供新见解的潜力，并进一步表明，亚轨道实验中的飞行中样本固定技术，将有助于解析飞行各阶段的生物响应。