Understanding the molecular mechanisms by which plants sense and adapt to changes in the space environment is essential for generating plants that are better adapted to withstand space flight, microgravity, and other adverse conditions encountered in space. The objective of our spaceflight experiment “Plant Signaling in Microgravity” (carried out on the International Space Station, ISS), was to compare transcript profiles of wild type and transgenic InsP 5-ptase plants with compromised InsP3 signaling. The transgenic Arabidopsis plants constitutively express the mammalian type I inositol polyphosphate 5-phosphatase (InsP 5-ptase), an enzyme that specifically hydrolyzes the lipid-derived second messenger inositol 1,4,5-trisphosphate (InsP3). These transgenic plants exhibit normal growth and morphology; however, their responses to environmental stimuli including gravity and drought are altered. Seedlings were grown for 5 days under continuous light in experimental containers placed in the European Modular Cultivation system (EMCS) onboard the ISS. The EMCS consists of two rotors within a controlled chamber, allowing for a “1g” control in space. After sample retrieval from the ISS, RNA was isolated from shoot and root tissue and subjected to RNA sequencing. Two-way comparisons of micro g versus “1”g have uncovered regulatory mechanisms that are both conserved and altered between the wild type and transgenic seedlings.

Spaceflight presents a unique environment with complex stressors, including microgravity and radiation, that can influence plant physiology at molecular levels. Combining transcriptomics and proteomics approaches, this research gives insights into the coordination of transcriptome and proteome in Arabidopsis’ molecular and physiological responses to Spaceflight environmental stress. Arabidopsis seedlings were germinated and grown in microgravity (µg) aboard the International Space Station (ISS) in NASA Biological Research in Canisters -Light Emitting Diode (BRIC LED) hardware, with the ground control established on Earth. At 10 days old, seedlings were frozen in RNA-later and returned to Earth. RNA-seq transcriptomics and TMT-labeled LC-MS/MS proteomic analysis of cellular fractionates from the plant tissues suggest the alteration of the photosynthetic machinery (PSII and PSI) in spaceflight, with the plant shifting photosystem core-regulatory proteins in an organ-specific manner to adapt to the microgravity environment. An overview of the ribosome, spliceosome, and proteasome activities in spaceflight revealed a significant abundance of transcripts and proteins involved in protease binding, nuclease activities, and mRNA binding in spaceflight, while those involved in tRNA binding, exoribonuclease activity, and RNA helicase activity were less abundant in spaceflight. CELLULOSE SYNTHASES (CESA1, CESA3, CESA5, CESA7) and CELLULOSE-LIKE PROTEINS (CSLE1, CSLG3), involved in cellulose deposition and TUBULIN COFACTOR B (TFCB) had reduced abundance in spaceflight. This contrasts with the increased expression of UDP-ARABINOPYRANOSE MUTASEs, involved in the biosynthesis of cell wall non-cellulosic polysaccharides, in spaceflight. Both transcripts and proteome suggested an altered polar auxin redistribution, lipid, and ionic intracellular transportation in spaceflight. Analyses also suggest an increased metabolic energy requirement for plants in Space than on Earth, hence, the activation of several shunt metabolic pathways. This study provides novel insights, based on integrated RNA and protein data, on how plants adapt to the spaceflight environment and it is a step further at achieving sustainable crop production in Space.

In this study transcriptome profiling was used to gain insight into the spaceflight adaptation role of Altered response to gravity-1 (Arg1) a gene known to affect gravity responses in plants on Earth. The study compared expression profiles of cultured lines of Arabidopsis thaliana derived from wild type (WT) cultivar Col-0 to profiles from a knock-out line deficient in the gene encoding (ARG1 KO) both on the ground and in space. The cell lines were launched on SpaceX CRS-2 as part of the Cellular Expression Logic (CEL) experiment of the BRIC17 spaceflight mission. The cultured cell lines were grown within 60mm Petri plates in Petri Dish Fixation Units (PDFUs) that were housed within the Biological Research In Canisters (BRIC) hardware. Spaceflight samples were fixed on orbit. Differentially expressed genes were identified between the two environments (spaceflight and comparable ground controls) and the two genotypes (WT and ARG1 KO). Each genotype engaged unique genes during physiological adaptation to the spaceflight environment with little overlap. Most of the genes altered in expression in spaceflight in WT cells were found to be Arg1-dependent suggesting a major role for that gene in the physiological adaptation of undifferentiated cells to spaceflight.

When germinated and grown on-board the ISS (International Space Station), plant do not exhibit abnormal structures but they do have altered growth habits and this project aims to investigate the molecular mechanisms that provide the foundation for the altered growth habits observed in orbit. APEX03-2 (Advanced Plant Experiment 03-2), also known as TAGES-ISA (Transgenic Arabidopsis Gene Expression System-Intracellular Signaling Architecture) specifically addresses the growth and molecular changes that occur in Arabidopsis thaliana plants during spaceflight by using molecular and genetic tools, and by asking fundamental questions regarding root structure, growth and cell wall remodeling may be answered. This investigation advances the fundamental understanding of the molecular biological responses to extraterrestrial environments. This understanding helps to further define the impacts of spaceflight on biological systems to better enable NASA's future space exploration goals.

Spaceflight is a unique environment with profound effects on biological systems including tissue redistribution and musculoskeletal stresses. However the more subtle biological effects of spaceflight on cells and organisms are difficult to measure in a systematic unbiased manner. Here we test the utility of the molecularly barcoded yeast deletion collection to provide a quantitative assessment of the effects of microgravity on a model organism. We developed robust hardware to screen in parallel the complete collection of ~4800 homozygous and ~5900 heterozygous (including ~1100 single-copy deletions of essential genes) yeast deletion strains each carrying unique DNA that acts as strain identifiers. We compared strain fitness for the homozygous and heterozygous yeast deletion collections grown in spaceflight and ground as well as plus and minus hyperosmolar sodium chloride providing a second additive stressor. The genome-wide sensitivity profiles obtained from these treatments were then queried for their similarity to a compendium of drugs whose effects on the yeast collection have been previously reported. We found that the effects of spaceflight have high concordance with the effects of DNA-damaging agents and changes in redox state suggesting mechanisms by which spaceflight may negatively affect cell fitness.

Spaceflight is a unique environment with profound effects on biological systems including tissue redistribution and musculoskeletal stresses. However the more subtle biological effects of spaceflight on cells and organisms are difficult to measure in a systematic unbiased manner. Here we test the utility of the molecularly barcoded yeast deletion collection to provide a quantitative assessment of the effects of microgravity on a model organism. We developed robust hardware to screen in parallel the complete collection of ~4800 homozygous and ~5900 heterozygous (including ~1100 single-copy deletions of essential genes) yeast deletion strains each carrying unique DNA that acts as strain identifiers. We compared strain fitness for the homozygous and heterozygous yeast deletion collections grown in spaceflight and ground as well as plus and minus hyperosmolar sodium chloride providing a second additive stressor. The genome-wide sensitivity profiles obtained from these treatments were then queried for their similarity to a compendium of drugs whose effects on the yeast collection have been previously reported. We found that the effects of spaceflight have high concordance with the effects of DNA-damaging agents and changes in redox state suggesting mechanisms by which spaceflight may negatively affect cell fitness.

In this study transcriptome profiling was used to gain insight into the spaceflight adaptation role of Altered response to gravity-1 (Arg1), a gene known to affect gravity responses in plants on Earth. The study compared expression profiles of cultured lines of Arabidopsis thaliana derived from wild type (WT) cultivar Col-0 to profiles from a knock-out line deficient in the gene encoding (ARG1 KO), both on the ground and in space. The cell lines were launched on SpaceX CRS-2 as part of the Cellular Expression Logic (CEL) experiment of the BRIC17 spaceflight mission. The cultured cell lines were grown within 60mm Petri plates in Petri Dish Fixation Units (PDFUs) that were housed within the Biological Research In Canisters (BRIC) hardware. Spaceflight samples were fixed on orbit. Differentially expressed genes were identified between the two environments (spaceflight and comparable ground controls) and the two genotypes (WT and ARG1 KO). Each genotype engaged unique genes during physiological adaptation to the spaceflight environment, with little overlap. Most of the genes altered in expression in spaceflight in WT cells were found to be Arg1-dependent, suggesting a major role for that gene in the physiological adaptation of undifferentiated cells to spaceflight.

In prospective human exploration of outer space the need to maintain a species over several generations under changed gravity conditions may arise. This paper reports the analysis of the third generation of fruit fly Drosophila melanogaster obtained during the 44.5-day space flight (Foton-M4 satellite 2014 Russia) followed by the fourth generation on Earth and the fifth generation under conditions of a 12-day space flight (2014 in the Russian Segment of the ISS). The obtained results show that it is possible to obtain the third-fifth generations of a complex multicellular Earth organism under changed gravity conditions (in the cycle weightlessness - Earth - weightlessness) which preserves fertility and normal development. However there were a number of changes in the expression levels and content of cytoskeletal proteins that are the key components of the spindle apparatus and the contractile ring of cells.

Arabidopsis thaliana wild type cell cultures were exposed to a 5-day space flight onboard of Shenzhou 8 to identify microgravity and space effect related gene expression.

DNA methylation is a very important kind of epigenetic modification and participates in many biological functions. Although many previous studies have addressed various plant species the study of global DNA methylation pattern in response to microgravity conditions has been quite limited. In this report we map the changes in Arabidopsis genome methylation patterns - at the single-base resolution - associated with microgravity conditions on board of the spacecraft SJ-10 mission in China.