Volume 4 (2016): Issue 2 (December 2016)

Future spacecraft and crew habitats are anticipated to use a moderately hypobaric and hypoxic cabin atmosphere to reduce the risk of decompression sickness associated with extravehicular activity. This has raised concerns about potential hypoxia-mediated adverse effects on astronauts. Noninvasive technology for measuring tissue oxygen saturation (StO₂) has been developed for clinical use and may be helpful in monitoring oxygenation during spaceflight. We conducted a technical evaluation of a handheld StO₂ monitor during a series of parabolic flights, and then undertook a preliminary analysis of the data obtained during the flights from six individuals. The StO₂ monitor operated normally in all gravity conditions. There was considerable variability in StO₂ between and within individuals. Overall, transition to microgravity was associated with a small decrease in StO₂ of 1.1±0.3%. This evaluation has established the basic function of this technology in microgravity and demonstrates the potential for exploring its use in space.

In order to use plants as part of a bioregenerative life support system capable of sustaining long-term human habitation in space, it is critical to understand how plants adapt to the stresses associated with extended growth in spaceflight. Optimally, dormant seeds would be germinated on orbit to divorce the effects of spaceflight from the one-time stresses of launch. At an operational level, it is also important to develop experiment protocols that are flexible in timing so they can adapt to crew schedules and unexpected flight-related delays. Arabidopsis thaliana is widely used for investigating the molecular responses of plants to spaceflight. Here we describe the development of a far-red light seed treatment device that suppresses germination of Arabidopsis seeds for periods of ≥12 weeks. Germination can then be induced when the seeds encounter red light, such as transfer to the illumination from on orbit plant growth hardware. This device allows for up to twelve 10×10 cm square Petri dishes containing seeds on nutrient gel to be irradiated simultaneously. The far-red device is contained within a light-proof fabric tent allowing the user to wrap the Petri dishes in aluminum foil in the dark, preventing room lights from reversing the far-red treatment. Long-term storage of the wrapped plates is accomplished using foil storage bags. The throughput of this device facilitates robust, high-replicate biological experiment design, while providing the long-term pre-experiment storage required for maximum mission flexibility.

Large-scale omics approaches make excellent choices for research aboard the International Space Station (ISS) because they provide large amounts of data that can be continually mined even after the original research has been completed. A proteomic approach can provide information about which proteins are produced, degraded, or post-translationally modified, potentially shedding light on cellular strategies that cannot be discerned from transcriptomic data. To collect sufficient tissue from a Biological Research In Canisters (BRIC)-grown experiment on the ISS for proteomic analysis, several modifications were made to existing protocols. Approximately 800–1000 seeds were housed in each Petri Dish Fixation Units (PDFU). These were germinated up to 120 h after planting by transferring the BRIC from cold stasis to room temperature. Growth continued for only 72 h after germination to allow sufficient tissue for extraction, and to minimize the impact of ethylene and crowding stress. Seedlings were then exposed to RNAlater®. Results indicate that RNAlater® - treated Arabidopsis seedlings yield an equal amount of protein to those flash-frozen in liquid nitrogen.

Spaceflight has a unique set of abiotic conditions to which plants respond by orchestrating genome-wide alterations to their transcriptome. The methods for preserving plants for RNA analysis are well-established and proven over multiple missions, but, methods for investigating the possible epigenetic mechanisms that may contribute to the transcriptome alteration are not well-developed for the confining limitations of the International Space Station (ISS). Currently, the methods used to isolate genomic DNA and to perform epigenetic analyses are ideal for frozen plants, as opposed to plants stored in RNAlater®—a high salt solution that chemically suspends all cellular activity and is typically used on the ISS. Therefore, we developed a method for extracting high-quality genomic DNA suitable for epigenetic analysis from Arabidopsis thaliana (Arabidopsis) plants that were preserved with the current preservation system aboard the ISS—fixation in RNAlater® using Kennedy Space Center Fixation Tubes (KFTs).

Spaceflight experiments offer a unique environment for fundamental research in biology. Utilization of microgravity environments has provided insights into how plants and animals perceive and respond to gravity, or the lack thereof. However, performing spaceflight experiments on the International Space Station (ISS) requires years of planning and testing before execution. A few of the complex steps preceding the experiment include: development of the experimental timeline and programming of experimental equipment, testing hardware for biocompatibility, planning the logistics of sending samples to NASA or ESA centers for testing, and launching samples to the ISS. In this paper, using the Seedling Growth-2 spaceflight experiment as an example, we cover the entire timeline leading up to a flight experiment. These events include the Schedule Test, the Operations and Validations Test (OVT), and the Flight Build and Experiment, as well as the post-flight sample processing.

Because of difficulties during the fixation in space and the often reported enhanced expression of stress-related genes in space experiments, we investigated the possible effect of fixation on gene expression. Comparing two fixatives (RNAlater^® and 70% ethanol), two-day-old Brassica rapa seedlings were either fixed by gradual exposure or immediate and complete immersion in fixative for two days. Neither fixative yielded high amounts of rRNA; RNAlater^® resulted in higher RNA yield in shoot tissue but qPCR data showed higher yield in ethanol-fixed material. qPCR analyses showed strongly enhanced transcripts of stress-related genes, especially in RNAlater^®-fixed material. The data suggest that fixation artefacts may be partially responsible for effects commonly attributed to space syndromes.

The NASA GeneLab Data System (GLDS) was recently developed to facilitate cross-experiment comparisons in order to understand the response of microorganisms to the human spaceflight environment. However, prior spaceflight experiments have been conducted using a wide variety of different hardware, media, culture conditions, and procedures. Such confounding factors could potentially mask true differences in gene expression between spaceflight and ground control samples. In an attempt to mitigate such confounding factors, we describe here the development of a standardized set of hardware, media, and protocols for liquid cultivation of microbes in Biological Research in Canisters (BRIC) spaceflight hardware, using the model bacteria Bacillus subtilis strain 168 and Staphylococcus aureus strain UAMS-1 as examples.

As an extension of NASA Ames’ long history and sustaining international collaboration for sharing tissues acquired from one-off spaceflight experiments, we have recently established a new mobile operation for acquiring small animal biospecimens from ongoing ground-based studies supported by the NASA Human Research Program (HRP) organized at Johnson Space Center (JSC). Goals of Ames’ Biospecimen Sharing Programs (BSPs) are to: (1) advance understanding of physiological responses and adaptations to the space environment utilizing animal models in support of fundamental space and gravitational biology research, and to promote human health in space and on Earth, (2) provide a repository of high-quality, well-preserved, and carefully archived and maintained biospecimens by applying modern approaches and established best practices in the biobanking field, and (3) establish a database for gathering broad and comprehensive scientific information corresponding to these samples, including cutting edge techniques for tracking and archiving of structural, descriptive, and administrative metadata. This program, modeled after contemporary human and animal biobanking initiatives, is yielding a rich archive of quality specimens that can be used to address a broad range of current and future scientific questions relevant to NASA Life Sciences, Exploration Medicine, and beyond.