rss_2.0Gravitational and Space Research FeedSciendo RSS Feed for Gravitational and Space Research and Space Research Feed (PES) Membrane on Agar Plates as a Plant Growth Platform for Spaceflight<abstract> <title style='display:none'>Abstract</title> <p>Plant biology experiments in microgravity face many challenges, among which are the constraints of the growth platforms available on the International Space Station (ISS). Protocols for preservation and sample return to Earth often limit efficient dissection of seedlings for downstream tissue-specific analysis. The Advanced Plant Experiment (APEx)-07 spaceflight experiment required a large quantity of dissectible, well-preserved seedlings suitable for omics analysis. During preflight tests, protocols were developed for using an agar-polyethersulfone (PES) membrane platform for seedling growth that allowed for seedling germination and growth aboard the ISS and rapid freezing to provide intact seedlings for dissection and extraction of high-quality DNA, RNA, and protein. Each component of the growth setup was carefully examined: membrane color, hydration and growth substrate, capacity for delayed germination, growth duration, harvest approach, and preservation pipelines were all individually optimized. Sterilized Arabidopsis seeds were adhered to PES membrane with guar gum. Membranes were laid onto 0.8% agar containing 0.5x Murashige and Skoog (MS) in 10 cm square Petri dishes and held at 4 °C until the experiment was actuated by placing the Petri dishes at room temperature. Seedlings were grown vertically for 12 days. PES membranes were removed from the agar, placed in the Petri dish lid, wrapped in foil, and frozen at −80 °C. Seedlings were dissected into roots and shoots and provided high-quality DNA, RNA, and protein. The system is simple, potentially adaptable for seedlings of multiple species, scalable and cost effective, and offers added versatility to existing ISS plant growth capabilities.</p> </abstract>ARTICLEtrue of Spaceflight Hardware for Plant Growth in a Sealed Habitat for Experiments on the Moon<abstract> <title style='display:none'>Abstract</title> <p>Plant growth experiments on near-term lunar landers need to be relatively small, lightweight, and self-contained. Here, we report on the design of a ~1 liter volume (1U Cubesat size) hermetically sealed habitat suitable for plant growth experiments during the first 10 days of seedling development of <italic>Arabidopsis thaliana and Brassica nigra</italic>. Images from a single interior camera show germination and provide quantitative data on seedling height, leaf area, and circumnutations. After 10 days with illumination from LEDs, the photosynthetic area of <italic>Arabidopsis</italic> cotyledons per seedling reached 300 mm<sup>2</sup>. Seedling height, inferred from the overhead camera using reference markers, reached was 15 ± 5 mm. Robust circumnutation in seedlings was observed. CO<sub>2</sub> increased as expected due to respiration in the seeds during germination reaching levels of 5000 ppm after 3 days before declining to 3000 ppm on day 10 due to photosynthetic uptake. No CO<sub>2</sub> was added to the sealed chamber during the experiments. These results show that fundamental studies of germination and initial growth can be conducted in a small volume (1 L) hermetically sealed unit with only an overhead camera and CO<sub>2</sub> sensor. Hardware based on this approach would be suitable for lunar experiments on robotic landers.</p> </abstract>ARTICLEtrue Novel Approach to Teaching a General Education Course on Astrobiology<abstract> <title style='display:none'>Abstract</title> <p>It is often a challenge to arouse much interest, motivation, and engagement in physical science courses among non-STEM majors. We attempt to address this difficulty and at the same time strive to achieve high levels of student learning by choosing a novel as the main text of the course. We created a context-rich course on astrobiology—the science of life in the universe—that uses Carl Sagan's <italic>Contact</italic> as the main text. We were able to teach the entire subject matter of a conventional course without omitting any topic. A typical class session included discussion of the science content of one chapter of Contact after students are assigned to read it and answer questions before the lecture. We assessed our approach with pretests and posttests that measure students’ knowledge of the key content areas, as well as students’ perceptions. We then calculate the students’ normalized gains, the effect size, and perform hypothesis testing. Our results show that this approach can result in substantial learning gains for students and at the same time improve students’ self-assessment and perceptions of science while not compromising the absolute learning gains.</p> </abstract>ARTICLEtrue Hypergravity-Induced Changes in Growth, Photo synthetic Parameters, and Assessment of Threshold Values in Wheat ( L.)<abstract> <title style='display:none'>Abstract</title> <p>The reduction in growth and development of plants constantly exposed to different ranges of hypergravity (acceleration more than 1 g) is adequately documented. However, earlier studies did not reveal the threshold hypergravity value at which these effects were seen. The understanding of the threshold g-value is an important consideration while we plan hypergravity experiments as different plants can perceive and respond differently at the same g-value. The aim of the present work is to study the effect on growth and photosynthetic parameters as well as to assess the threshold values in wheat seedlings grown from hypergravity-exposed seeds. Healthy wheat seeds were immersed in distilled water for 24 hours and exposed to hypergravity values ranging from 200 g to 1,000 g for a short duration of 10 minutes and sown on 0.8% agar gel. All the measurements were done on the fifth day after sowing. Results obtained showed significant reduction in growth and photosynthetic parameters in seedlings raised from hypergravity-treated wheat seeds. Interestingly, the reduction was started at 400 g and was found to reach a maximum at 1,000 g. Probably this would be the first study reporting the threshold of high g forces for growth and photosynthetic parameters when seeds were exposed to hypergravity.</p> </abstract>ARTICLEtrue Agglomeration of Bimodal Colloids under Microgravity<abstract> <title style='display:none'>Abstract</title> <p>A study of like-charged, bimodal colloidal suspensions was conducted in microgravity aboard the International Space Station as part of NASA's Advanced Colloids Experiments-Heated-2 (ACE-H-2) experiments. Samples comprised of silsesquioxane microparticles (600 nm) and zirconia nanoparticles (5–15 nm) in 1.5 pH nitric acid were mixed and allowed to agglomerate over time while being imaged with NASA's Light Microscopy Module (LMM). The samples contained 1% of microparticles with varying concentrations of nanoparticles in 0.1%, 0.055%, and 0.01% by volume. Digital images were captured periodically by the LMM over 12 days. Image analysis, including cluster size and distribution, was performed in Python using the “Colloidspy” package. The study found that cluster size had increased over time in at least seven of nine samples, but two samples exhibited nonlinear growth rates, while others showed very slow growth with cluster sizes two orders of magnitude greater than the free microparticles. We hypothesize that all samples experienced nonlinear growth, but early transient effects after mixing were missed due to timing limitations in image acquisition. Transport limitations of clusters in these systems may have dominated agglomeration behavior in microgravity, despite the samples being thermodynamically unstable, but more study is required.</p> </abstract>ARTICLEtrue Experimenter's Experiences in Early Commercial Suborbital Flight<abstract><title style='display:none'>Abstract</title><p>The emerging commercial suborbital rocket industry in the U.S. presents new opportunities for research and education missions. Some companies have been publicized by the world's media and others are lower-profile. Additionally, some companies were created for the space tourism market and others have no current plans to fly humans at all. Most companies already have a Payload User's Guide published at their websites. The time for experimenters to take note of this industry is now, because in early 2014 a number of these companies were already operational or in flight test phase of their business development. When thousands of dollars, instead of millions for traditional NASA or European Space Agency (ESA) sounding rockets, are needed for a suborbital flight, many more researchers will be able to afford suborbital testing and research. In general, these rocket companies seek to provide at least three minutes of high-quality weightless test times from approximately 60 km to 100 km in altitude, and back to 60 km. Purdue University has been fortunate to have secured numerous launches for small payloads during these developmental and early operational years of the industry. Lessons from these launches include lessons in design, payload environment, procedures, launch site infrastructure, and travel preparations.</p></abstract>ARTICLEtrue Balloon-Based Payload for Exposing Microorganisms in the Stratosphere (E-MIST)<abstract><title style='display:none'>Abstract</title><p>The survival and transit of microorganisms in Earth's upper atmosphere is relevant to terrestrial ecology and astrobiology, but the topic is understudied due to a scarcity of suitable flight systems. We designed, built, and flew a self-contained payload, Exposing Microorganisms in the Stratosphere (E-MIST), on a large scientific balloon launched from New Mexico on 24 August 2014. The payload carried <italic>Bacillus pumilus</italic> SAFR-032, a highly-resilient spore-forming bacterial strain originally isolated from a NASA spacecraft assembly facility. Our test flight evaluated E-MIST functionality in the stratosphere, including microbiological procedures and overall instrument performance. Herein, we summarize features of the E-MIST payload, protocols, and preliminary results that indicate it is possible to conduct a tightly-controlled microbiological experiment in the stratosphere while collecting pertinent environmental data. Additional studies of this nature may permit survival models for microbes traveling through Earth's harsh upper atmosphere. Moreover, measuring the endurance of spacecraft-associated microbes at extreme altitudes may help predict their response on the surface of Mars.</p></abstract>ARTICLEtrue Oxalate Crystal Yield in Various Gravity Environments<abstract><title style='display:none'>Abstract</title><p>An experimental chamber and hand-manipulated syringe apparatus were designed, tested, and utilized to assess calcium oxalate crystal yield in Terrestrial-<italic>g</italic> (1 <italic>g</italic>), micro-<italic>g</italic> (0.01 <italic>g</italic>), Lunar-<italic>g</italic> (0.16 <italic>g</italic>), and Martian-<italic>g</italic> (0.38 <italic>g</italic>). Aqueous solutions of calcium chloride (100 mM) and oxalic acid (200 mM) were mixed to precipitate calcium oxalate crystals. Gravitational differences were hypothesized to result in differences in the yield of crystal formation. These data are essential for efforts to better understand the correlation between calcium oxalate crystal formation and the production of kidney stones often associated with long-term space missions. The analyses of crystal formation produced in the micro-<italic>g</italic> (≅0.01 <italic>g</italic>) conditions of this study suggest that calcium oxalate monohydrate formation yield is slightly greater than those produced in Terrestrial-<italic>g</italic> conditions.</p></abstract>ARTICLEtrue Vehicles to Study Transition Adaptation to Spaceflight – Why Biologists Should Care About the New Suborbital Flight Opportunities<abstract><title style='display:none'>Abstract</title><p>The advent of the new generation of suborbital space vehicles is opening up a new and exciting realm of space science that should be of great interest to biologists. These vehicles make it possible to explore biological responses and adaptations that occur in the first few minutes of entering spaceflight and also in the first few minutes after return from space. Historically these transition stages in spaceflight have simply not been available for research, especially within human-rated vehicles. Given that complex biological responses are seldom linear over time, and that essentially all current experiments on the International Space Station (ISS) are conducted after stabilization on orbit, biologists are missing the chance to understand the pathways that lead from terrestrial existence to successful spaceflight adaptation and back. Studies conducted on suborbital spacecraft can therefore be an innovative approach to filling a substantial gap in knowledge regarding the temporal dynamics of biological responses to successful spaceflight physiological adaptation.</p></abstract>ARTICLEtrue Within a Simulated Microgravity Environment - Promotes the Growth of<abstract><title style='display:none'>Abstract</title><p>The endophytic fungus, <italic>Piriformospora indica</italic>, developed a subepidermal infection within <italic>Medicago truncatula</italic> at 1 <italic>g</italic> and at simulated microgravity over a period of 15 days, resulting in intracellular colonization of mature host tissue. At 1 <italic>g</italic>, <italic>P. indica</italic> inoculation affected the growth and morphology of <italic>M. truncatula</italic>, predominantly roots. Inoculated <italic>M. truncatula</italic> had a significantly greater number of roots (102%), total root length (88%), and dry root weight (25%) than non-inoculated plants. Effects on shoot morphology of <italic>P. indica</italic> inoculated <italic>M. truncatula</italic> included longer (31%) and heavier (30%) shoots, along with increased leaf surface area (98%). <italic>P. indica</italic> retained the ability to promote the growth of <italic>M. truncatula</italic> under simulated microgravity conditions upon two dimensional clinostatic rotation, significantly increasing root number by 51% and root length by 48%. These physiological and morphological changes may mitigate biotic and abiotic stresses that would otherwise limit crop productivity.</p></abstract>ARTICLEtrue for Spaceflight Applications–Preparing Dormant Biology for Passive Stowage and On-Orbit Activation<abstract><title style='display:none'>Abstract</title><p>Biological experiments on-orbit that demonstrate the effects of gravity on plants require precise control of the initiation of plant development. Preserving seed dormancy is critical to experiments that endeavor to study the effects of the orbital environment, independent of contributions from either a normal gravity, or launch. However, spaceflight experiments are often tightly constrained with respect to the configuration of the biology and associated hardware, and it is rarely possible to launch dry seeds separated from their growth substrate. Described here are techniques established to maintain viable seeds that can remain dormant for up to a month at room temperature, and hydrated on the surface of solid, Phytagel growth medium. The configuration can also accommodate a brief (less than one minute) exposure to light during the quiescent period for quick inspection for any breaks in dormancy, and for contamination. The data presented outline the preparation of sealed, Phytagel media plates of dormant <italic>Arabidopsis thaliana</italic> seed that can be activated <italic>in situ</italic> when unwrapped and installed within a lighted growth habitat. These protocols were developed primarily for spaceflight scenarios where seeded plates must be prepared ahead of time and kept at ambient temperatures. However, these protocols can be adapted for any field application where it is desirable to transport dormant, seeded plates to a remote location where it would not be possible to prepare sterile culture plates.</p></abstract>ARTICLEtrue Axis Rotational Assessment of Transdermal Scopolamine for Motion Sickness Prophylaxis<abstract><title style='display:none'>Abstract</title><p>The objectives of this study were to evaluate transdermal scopolamine for motion sickness prophylaxis, and to evaluate off-vertical axis rotation (OVAR) as a laboratory model of motion sickness. This was a randomized, prospective, double-blind study design, set in a vestibular research laboratory. The experimental subjects consisted of 12 patients – 7 male, 5 female – ages 21 to 57, with normal auditory/vestibular function. The intervention was off-vertical axis rotation 20 degrees in the dark after administration of transdermal scopolamine or placebo. The main outcome measures were time duration of tolerated off-vertical rotation, and subjective symptom reporting during rotation at one-minute intervals on a 0–4 scale. Results were as follows: patients treated with transdermal scopolamine had statistically significant improved tolerance time to off-vertical axis rotation. Reported symptom-atology on the 0–4 subjective symptom scale was significantly improved, as compared to placebo, and was dose-dependent. Conclusions are as follows: off-vertical axis rotation is a useful modality for the evaluation of motion sickness medications. Transdermal scopolamine showed statistically significant dose-dependent effects in mitigating OVAR-induced motion sickness symptomatology and was well tolerated.</p></abstract>ARTICLEtrue Effects of Gamma and Proton Radiation Exposure on Hematopoietic Cell Counts in the Ferret Model<abstract> <title style='display:none'>ABSTRACT</title> <p>Exposure to total-body radiation induces hematological changes, which can detriment one’s immune response to wounds and infection. Here, the decreases in blood cell counts after acute radiation doses of γ-ray or proton radiation exposure, at the doses and dose-rates expected during a solar particle event (SPE), are reported in the ferret model system. Following the exposure to γ-ray or proton radiation, the ferret peripheral total white blood cell (WBC) and lymphocyte counts decreased whereas neutrophil count increased within 3 hours. At 48 hours after irradiation, the WBC, neutrophil, and lymphocyte counts decreased in a dose-dependent manner but were not significantly affected by the radiation type (γ-rays verses protons) or dose rate (0.5 Gy/minute verses 0.5 Gy/hour). The loss of these blood cells could accompany and contribute to the physiological symptoms of the acute radiation syndrome (ARS).</p> </abstract>ARTICLEtrue in the Animal Enclosure Module Spaceflight Hardware Increases Trabecular Bone Mass in Ground-Control Mice<abstract> <title style='display:none'>ABSTRACT</title> <p>During spaceflight, mice are housed in specially designed cages called the Animal Enclosure Module (AEM). Utilization of this flight hardware may affect the skeletal properties of housed animals, independent of microgravity considerations. To address this issue, we studied the effect of 13 days of AEM housing versus standard vivarium enclosure on female C57BL/6J mice (n=12/group). The effects of AEM housing were most pronounced in the trabecular compartment. AEM mice had 44% and 144% greater trabecular bone volume fraction and connectivity density, respectively, versus vivarium. A similar response was seen at the proximal humerus. We noted a decrease in proximal tibia osteoclast surface (-65%) and eroded surface (-73%) for AEM versus vivarium, while tibia trabecular mineralizing surface (MS/BS) was nearly three-fold greater. Surprisingly, there was also decreased osteoblast surface, as well as lower osteoid volume, surface, and thickness at this site. The effects of AEM housing on femur cortical bone were modest: there was greater periosteal MS/BS, with no effect at the endocortical surface, and lower femur stiffness. Taken together, we have demonstrated significant effects of AEM housing on ground control mice, particularly in the trabecular bone compartment. These findings suggest that an early increase in bone formation, perhaps due to altered behavior and loading in this unique housing environment, was followed by decreased bone formation and resorption as the animals adapted to their new environment. Characterization of spaceflight animal housing is critical to elucidating the true effects of microgravity on skeletal parameters and for the proper selection of ground-based controls.</p> </abstract>ARTICLEtrue in Altered Gravity Influences Height in<abstract> <title style='display:none'>ABSTRACT</title> <p>We investigated the effects of altered gravity on the life cycle of <italic>Dictyostelium discoideum</italic> after and during life-long exposure to one of three altered gravity (<italic>g)</italic> environments: (1) substrate inverted, parallel to and facing the surface of the Earth; (2) hyper-<italic>g</italic>; (3) reduced-<italic>g</italic>. To this end, we measured the height of the final stage of the life cycle, the mature spore-bearing sorocarp. Typically, the sorocarp stands erect and perpendicular to the substrate. In the case of each altered <italic>g</italic> environment, the control cultures were produced and treated identically to the experimental cultures except for the conditions of their exposure to altered <italic>g</italic>. Inverted cultures developing and growing in the same direction as the gravity vector had a mean height of 1.84 mm. Their counterpart control cultures had a mean height of 1.64 mm being therefore statistically significantly shorter. Cultures chronically exposed to a hyper (10) <italic>g</italic> environment produced sorocarps with a mean height of 1.13 mm. These were statistically significantly shorter than their 1 <italic>g</italic> controls whose mean height was 2.06 mm. Clinorotated (simulated reduced <italic>g</italic>) sorocarp heights (mean equal to 2.12 mm) were statistically significantly taller compared to their 1 <italic>g</italic> controls (mean equal to 1.79 mm). The significance level for all the statistical analyses is p &lt; 0.05. Therefore, measurements of the mature stage after life-long exposure to simulated altered gravity show that the final height of the sorocarp is ultimately determined, at least partially, by the gravity environment in which development occurs.</p> </abstract>ARTICLEtrue Reproduction and Development on the International Space Station (ISS): Proceedings of the Rodent Mark III Habitat Workshop<abstract> <title style='display:none'>ABSTRACT</title> <p>The <italic>Mark III Rodent Habitat Workshop</italic> was held at NASA Ames Research Center on March 21-22, 2013 to prepare top-level science requirements for developing a habitat to support studies of mammalian reproduction and development on the International Space Station (ISS). This timely workshop assembled a diverse team with expertise in reproductive and developmental biology, behavior, space biosciences, habitat development, physiology, mouse genetics, veterinary medicine, rodent husbandry, flight hardware development (rodent), and spaceflight operations. Participants received overview presentations from each discipline, discussed concerns, potential risks, and risk mitigations corresponding to distinctive reproductive and developmental phases, and reviewed specific examples of research within the major space bioscience disciplines requiring a Mark III habitat<sup><xref ref-type="fn" rid="j_gsr-2013-0009_fn_001">1</xref></sup> to achieve their objectives. In this review, we present the workshop materials and products, and summarize major recommendations for defining the requirements envelope for the NASA Rodent Habitat (RH) Mark III. Development of this habitat will permit the first long duration studies of mammalian reproduction and development in space, within and across generations.</p> </abstract>ARTICLEtrue Computational Study of the Mechanics of Gravity-induced Torque on Cells<abstract> <title style='display:none'>ABSTRACT</title> <p>In this paper we use Nace’s previous work in order to model the effects of gravity in cells and similar objects. In the presence of the gravitational field of a primary body, the gravity vector can result in numerous effects, some of which are tension, shear, and finally torque. To model the torque effect we use a complete expression for the gravitational acceleration, as this is given on the surface of a planetary body as well as in orbit around it. In particular, on the surface of the Earth the acceleration is corrected for the effect of oblateness and rotation. In the gravitational acceleration the effect of oblateness can be modeled with the inclusion of a term that contains the <italic>J</italic><sub>2</sub> harmonic coefficient, as well as a term that depends on the square of angular velocity of the Earth. In orbit the acceleration of gravity at the point of the spacecraft is a function of the orbital elements and includes, only in our case, the <italic>J</italic><sub>2</sub> harmonic since no Coriolis force is felt by the spacecraft. We derive analytical expressions and calculate the resulting torque effects for various geocentric latitudes, as well as circular and elliptical orbits of various eccentricities and inclinations. We find that elliptical polar orbits result in higher torques, and that higher eccentricities result in higher the torque effects. To any measurable extent, our results do not drastically impact any existing biophysical conclusions.</p> </abstract>ARTICLEtrue Species and Media Selection for the Veggie Space Hardware<abstract> <title style='display:none'>ABSTRACT</title> <p>Plants will be an important component of off-Earth life support systems for food production and atmosphere recycling. “Veggie” is a small vegetable production unit designed for space flight, with a passive water delivery system. Plants can be grown in Veggie using small bags with a wicking surface containing media and fertilizer, i.e., pillows. Pillows planted with seeds can be placed on the wicking surface of the Veggie reservoir and water will wick throughout the media. Multiple small salad and herb species were grown in Veggie analog conditions using both commercial peat-based media and arcillite. Biometric measurements and microbial loads were assessed. Some species grew better in a particular media, but no general trends were apparent. Lettuce plants grew best in the blends of the peat-based and arcillite media. Microbial counts were lower on plants grown in arcillite. Four media types (peat-based mix, arcillite, and blends of the two) were tested in the rooting pillows; tests included Chinese cabbage, Swiss chard, lettuce, snow pea, and radish. Most species grew best in blends of the commercial mix and arcillite. Edible biomass production varied from 3.5-8 grams dry mass/m<sup>2</sup>/day with lettuce having the lowest biomass and Chinese cabbage highest. Radish plants showed an increasing percentage of partitioning to edible roots with increasing arcillite in the media. Pillows appear to offer a simple, effective strategy for containing rooting media and avoiding free water while growing plants in the Veggie hardware.</p> </abstract>ARTICLEtrue Effects of Spaceflight on Mucin Production in the Mouse Uterus<abstract> <title style='display:none'>ABSTRACT</title> <p>The effects of microgravity on biological tissues are relatively unexplored, especially in regard to the mammalian female reproductive system. To begin to address this issue, the uterine tissue of female mice flown on NASA shuttle mission STS-118 was studied. Three sets of female mice, each consisting of 12 animals, were utilized in this study: flight animals, ground control animals, and baseline animals. The flight animals were housed in the Animal Enclosure Module (AEM) of the Commercial Biomedical Testing Module-2 (CBMT-2), which was a part of the payload of the shuttle’s mid-deck locker. Ground control animals were housed in ground-based AEMs, which were kept in a room specifically designed to mimic the environmental conditions of the flight units with regard to temperature, humidity, and light/dark cycles on a 48 hour delay. Baseline animals were housed in standard rodent cages at ambient temperature and humidity and a 12/12 light/dark cycle. The uterine tissue was stained using an Alcian Blue Periodic Acid Schiff staining procedure and the apical mucin layer thickness was subsequently analyzed. Analysis of the mucin layer in the uterus revealed that the thickness of the mucin layer in the flight tissue was significantly thicker that the mucin layers of the ground control and baseline tissue.</p> </abstract>ARTICLEtrue Effects and Molecular Responses in the Mouse Eye: Preliminary Observations After Shuttle Mission STS-133<abstract> <title style='display:none'>ABSTRACT</title> <p>Spaceflight exploration presents environmental stressors including microgravity-induced cephalad fluid shift and radiation exposure. Ocular changes leading to visual impairment in astronauts are of occupational health relevance. The effect of this complex environment on ocular morphology and function is poorly understood. Female 10-12 week-old BALB/cJ mice were assigned to a flight (FLT) group flown on shuttle mission STS-133, Animal Enclosure Module ground control group (AEM), or vivarium-housed (VIV) ground controls. Eyes were collected at 1, 5, and 7 days after landing and were fixed for histological sectioning. The contralateral eye was used for gene expression profiling by RT-qPCR. Sections were visualized by hematoxylin/eosin stain and processed for 8-hydroxy-2’-deoxyguanosine (8-OHdG), caspase-3, and glial fibrillary acidic protein (GFAP) and β-amyloid double-staining. 8-OHdG and caspase-3 immunoreactivity was increased in the retina in FLT samples at return from flight (R+1) compared to ground controls, and decreased at day 7 (R+7). β-amyloid was seen in the nerve fibers at the post-laminar region of the optic nerve in the flight samples (R+7). Expression of oxidative and cellular stress response genes was upregulated in the retina of FLT samples upon landing, followed by lower levels by R+7. These results suggest that reversible molecular damage occurs in the retina of mice exposed to spaceflight and that protective cellular pathways are induced in the retina and optic nerve in response to these changes.</p> </abstract>ARTICLEtrue