<abstract xmlns="http://www.w3.org/1999/xhtml">

Recent spaceflight experiments have provided many new insights into the role of gravity in plant growth and development. Scientists have been taking seeds and plants into space for decades in an effort to understand how the stressful environment of space affects them. The resultant data have yielded significant advances in the development of advanced life-support systems for long-duration spaceflight and a better understanding of the fundamental role of gravity in directing the growth and development of plants. Experiments have improved as new spaceflight hardware and technology paved the way for progressively more insightful and rigorous plant research in space. The International Space Station (ISS) has provided an opportunity for scientists to both monitor and control their experiments in real-time. Experiments on the ISS have provided valuable insights into endogenous growth responses, light responses, and transcriptomic and proteomic changes that occur in the microgravity environment. In recent years most studies of plants in space have used <italic>Arabidopsis thaliana</italic>, but the single-celled, <italic>Ceratopteris richardii</italic> spore is also a valuable model system that has been used to understand plant gravity response. Experiments using these fern spores have revealed a dynamic and gravity-responsive trans-cell Ca2+ current that directs polarization of these spores and a possible role of extracellular nucleotides in establishing or contributing to this current. As technology continues to improve, spaceflight experiments will provide many new insights into the role and effects of gravity on plant growth and development.
</abstract>

New Insights in Plant Biology Gained from Research in Space

<abstract xmlns="http://www.w3.org/1999/xhtml">

Gravity is a fundamental stimulus that affects plant growth and development. The gravity persistent signal (GPS) treatment uses a cold treatment to isolate the events of signal transduction. Plants are reoriented horizontally in the dark at 4°C for 1 hour and then returned to vertical at room temperature. A gene expression microarray was designed to identify genes that are regulated during the GPS treatment. <italic>Arabidopsis thaliana</italic> var. Columbia was grown to maturity with inflorescence stems of 8-10 cm. Total mRNA was collected from inflorescence stems at 2, 4, 10, and 30 min after reorientation in the cold. cDNA was synthesized from the mRNA and then probed against an Arabidopsis gene expression array with 4 replicates per time point. Analyses presented here focus on transcription factors because of their regulatory functions in response pathways. Five transcription factors (<italic>AtAIB, WRKY18, WRKY26, WRKY33</italic>, and <italic>BT2)</italic> were selected for further study based on their expression at 4 min. Quantitative real-time polymerase chain reaction ((PCR) RT-qPCR) was performed to confirm expression seen in the microarray data. Seeds of Arabidopsis lines containing T-DNA insertions in the genes were obtained, plants bred to homozygosity, and the mutants analyzed for GPS phenotype. Mutant analysis shows significant differences in curvature of inflorescence stems between mutants and wild type.
</abstract>

Microarray Identifies Transcription Factors Potentially Involved in Gravitropic Signal Transduction in Arabidopsis

<abstract xmlns="http://www.w3.org/1999/xhtml">

In order to meet heat rejection requirements for future NASA exploration, scientific, and discovery missions, a study is being conducted for the feasibility of integral variable conductance planar heat pipe (VCPHP) technology. This represents a novel, low technology readiness level (TRL) heat rejection technology that, when developed, could operate efficiently and reliably across a wide range of thermal environments. The concept consists of a planar heat pipe whose evaporator acquires the excess thermal energy from the thermal control system and rejects it at its condenser whose outer surface acts as a radiating surface. The heat pipe is made from thermally conductive polymers in order to minimize its mass. It has a non-condensable gas that changes the active radiator surface depending on the heat load. A mathematical model of steady-state variable conductance heat pipe is developed. Two planar heat pipes are designed, fabricated, and tested to validate the theoretical model. The feasibility of the proposed VCPHP working in a space environment is discussed, based on the model.
</abstract>

Compact Heat Rejection System Utilizing Integral Variable <italic>Conductance Planar</italic> Heat Pipe Radiator for Space Application

<abstract xmlns="http://www.w3.org/1999/xhtml">

The effects of spaceflight on yeast have high concordance with agents that induce a very low intracellular redox state and induce a massive efflux of glutathione. These results raise important issues. Can the reduced redox state during spaceflight be reproduced and modulated in ground-based simulations? Will this allow definition of unique drug pathways as a low redox potential state mirrors the electrophilic properties of mitochondria where many drugs are metabolized? Unfortunately, assays for redox status and its major cellular determinant—glutathione—are diverse and often cell-type-specific. Currently, an accepted redox probe set for yeast studies is not available. This paper validates fluorescent probes for glutathione and reactive oxygen status in yeast to support mechanistic studies of microgravity and drug metabolism. The plethora of fluorescent reagents for reactive oxygen species and glutathione makes head-to-head comparisons of all the alternatives impractical. These reagents measure the physiological milieu of reactive oxygen species and diverse thiols, rather than specific individual molecules. We report that in yeast, monochlorobimane (mBCL) and 2’,7’-dichlorodihydrofluorescein diacetate (DC-FDA) are suitable for fluorometric and flow cytometry studies of glutathione and reactive oxygen species, respectively. Both dyes have low background fluorescence, predictable loading, good retention, and are not acutely toxic to <italic>Saccharomyces cerevisiae</italic>. Both dyes show concordance with other fluorescent and biochemical assays of reactive oxygen species.
</abstract>

Validation of Assays for Reactive Oxygen Species and Glutathione in <italic>Saccharomyces cerevisiae</italic> during Microgravity Simulation

<abstract xmlns="http://www.w3.org/1999/xhtml">

Vascular patterning is a key, genetically responsive phylogenetic classifier of tissues in major organisms flown in space, such as the wings of <italic>Drosophila melanogaster</italic> (the fruit fly), mouse retina, and leaves of <italic>Arabidopsis thaliana</italic>. Phenotypes of increasingly abnormal ectopic wing venation in the highly stereotyped <italic>Drosophila</italic> wing generated by overexpressing the <italic>H-C2</italic> construct of <italic>Notch</italic> antagonist <italic>Hairless</italic> (<xref ref-type="bibr" rid="j_gsr-2015-0011_ref_013">Johannes and Preiss, 2002</xref>) were mapped and quantified by NASA’s VESsel GENeration Analysis (VESGEN) software. By several confirming vascular parameters, the eight stereotyped wing veins remained quite constant in wild type compared to Class 5 <italic>H-C2</italic>, the most perturbed category of the H-C2 overexpression phenotypes. However, ectopic veins increased in number from 1 in the wild type, to 18 in Class 5 <italic>H-C2</italic>. We therefore demonstrate the feasibility of using VESGEN to quantify microscopic images of altered wing venation in <italic>Drosophila melanogaster</italic>. We further determined that several of the signal transduction pathways affecting wing vein patterning were altered by spaceflight, according to gene expression differences observed in our transcriptomic data from a previous shuttle flight experiment. Future studies will help characterize the extent to which these gene expression changes can cause even subtle developmental changes using model organisms, such as <italic>Drosophila</italic>. Therefore, we propose that the sensitive analyses provided by VESGEN software will not only serve as a useful tool to map the genetics of wing vein patterning for terrestrial applications, but also for future phenotypic studies with <italic>Drosophila</italic> for spaceflight missions.
</abstract>

Mapping by VESGEN of Wing Vein Phenotype in <italic>Drosophila</italic> for Quantifying Adaptations to Space Environments

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Gravitational and Space Research

 Gravitational and Space Research is the main journal of the American Society for Gravitational and Space Research (ASGSR) and publishes quality, peer-reviewed manuscripts in several categories of, both life and physical space sciences. The Aims &amp; Scope of the journal encompasses the diversity of research on gravitational research and includes any topic within the following broad categories: the impact of gravity and changes in the gravity vector on biology, astrobiology, spaceflight and planetary analog environment research, advanced life support, biophysics, radiation biology, human-tended spaceflight, satellite payloads, suborbital research, parabolic flight, sounding rockets, high altitude balloons, hardware engineering and development, acceleration in altered gravity environments, combustion science, complex fluids, fluid physics, fundamental physics, and materials science. In addition, research wholly dedicated to terrestrial explorations of the impact of gravity and to changes in the gravity vector is welcome. The categories of papers include Short Communication, Methods, Research, Hypothesis, and Review. We are also open to publishing Educational Outreach papers in gravitational and space sciences.  Gravitational and Space Research is under the editorial leadership of Editor-in-Chief Jamie S. Foster, Ph.D., Professor in the Department of Microbiology and Cell Science at the University of Florida. There are no page charges associated with publishing in Gravitational and Space Research. All articles are Open-Access.  Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 

Gravitational and Space Research

Volume 3 (2015): Issue 2 (December 2015)

Review

New Insights in Plant Biology Gained from Research in Space

Short Communication

Microarray Identifies Transcription Factors Potentially Involved in Gravitropic Signal Transduction in Arabidopsis

Research Article

Compact Heat Rejection System Utilizing Integral Variable Conductance Planar Heat Pipe Radiator for Space Application

Validation of Assays for Reactive Oxygen Species and Glutathione in Saccharomyces cerevisiae during Microgravity Simulation

Mapping by VESGEN of Wing Vein Phenotype in Drosophila for Quantifying Adaptations to Space Environments

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