Microsome-associated proteome modifications of Arabidopsis seedlings grown on board the International Space Station reveal the possible effect on plants of space stresses other than microgravity

11p.-2 fig.-6 tab.Growing plants in space for using them in bioregenerative life support systems during long-term human spaceflights needs improvement of our knowledge in how plants can adapt to space growth conditions. In a previous study performed on board the International Space Station (GENARA A experiment STS-132) we evaluate the global changes that microgravity can exert on the membrane proteome of Arabidopsis seedlings. Here we report additional data from this space experiment, taking advantage of the availability in the EMCS of a centrifuge to evaluate the effects of cues other than microgravity on the relative distribution of membrane proteins. Among the 1484 membrane proteins quantified, 227 proteins displayed no abundance differences between µ g and 1 g in space, while their abundances significantly differed between 1 g in space and 1 g on ground. A majority of these proteins (176) were over-represented in space samples and mainly belong to families corresponding to protein synthesis, degradation, transport, lipid metabolism, or ribosomal proteins. In the remaining set of 51 proteins that were under-represented in membranes, aquaporins and chloroplastic proteins are majority. These sets of proteins clearly appear as indicators of plant physiological processes affected in space by stressful factors others than microgravity.The authors would like to thank the National Aeronautics and Space Administration (NASA) who successfully performed the spaceflight experiment; they also thank the astronauts for performing the required tasks on board the ISS. We acknowledge the Norwegian User Support and Operations Center team (NUSOC) for the ground and space preparation of the GENARA-A experiment and we thank the European Aeronautic Defense and Space Company (Astrium EADS) for the design and building of the hardware. We also thank the European Space Agency (ESA) and the Centre National d’Etudes Spatiales(CNES) for their scientific and financial support.Peer reviewe

Microgravity Induces Changes in Microsome-Associated Proteins of Arabidopsis Seedlings Grown on Board the International Space Station

International audienceThe ''GENARA A'' experiment was designed to monitor global changes in the proteome of membranes of Arabidopsis thaliana seedlings subjected to microgravity on board the International Space Station (ISS). For this purpose, 12-day-old seedlings were grown either in space, in the European Modular Cultivation System (EMCS) under microgravity or on a 1 g centrifuge, or on the ground. Proteins associated to membranes were selectively extracted from microsomes and identified and quantified through LC-MS-MS using a label-free method. Among the 1484 proteins identified and quantified in the 3 conditions mentioned above, 80 membrane-associated proteins were significantly more abundant in seedlings grown under microgravity in space than under 1 g (space and ground) and 69 were less abundant. Clustering of these proteins according to their predicted function indicates that proteins associated to auxin metabolism and trafficking were depleted in the microsomal fraction in mg space conditions, whereas proteins associated to stress responses, defence and metabolism were more abundant in mg than in 1 g indicating that microgravity is perceived by plants as a stressful environment. These results clearly indicate that a global membrane proteomics approach gives a snapshot of the cell status and its signaling activity in response to microgravity and highlight the major processes affected

Perspectives for plant biology in Space and analogue environments

Advancements in plant Space biology are required for the realization of long-duration exploratoryclass manned missions, where the re-supply of resources from Earth is not feasible for technical and economic constraints. Plants are key organisms in Bioregenerative Life Support Systems (BLSS) for the regeneration of resources (i.e. oxygen production through photosynthesis, water recovery by transpiration, and wastes recycling) and the production of fresh healthy food. Moreover, plants play a role in psychological support for astronauts. The definition of cultivation requirements for the design, realization and successful operation of BLSS must take into account the effects of Space factors on plant growth, development and reproduction. Altered gravitational fields and radiation exposure are the main Space factors inducing changes in gene expression, cell proliferation and differentiation, signaling and physiological processes, with consequences on tissue organization and organogenesis, thus on the whole organisms functioning. In this paper, the main findings of gravityand radiation-related research of the last years are summarized, highlighting the knowledge gaps that is still necessary to fill. A focus on existing facilities as well as requirements for future facilities to achieve fundamental biology goals is reported. Possible future experiments in the short-mediumlong term are proposed to achieve the targets of crewed Space exploration

Perspectives for plant biology in space and analogue environments

Abstract Advancements in plant space biology are required for the realization of human space exploration missions, where the re-supply of resources from Earth is not feasible. Until a few decades ago, space life science was focused on the impact of the space environment on the human body. More recently, the interest in plant space biology has increased because plants are key organisms in Bioregenerative Life Support Systems (BLSS) for the regeneration of resources and fresh food production. Moreover, plants play an important role in psychological support for astronauts. The definition of cultivation requirements for the design, realization, and successful operation of BLSS must consider the effects of space factors on plants. Altered gravitational fields and radiation exposure are the main space factors inducing changes in gene expression, cell proliferation and differentiation, signalling and physiological processes with possible consequences on tissue organization and organogenesis, thus on the whole plant functioning. Interestingly, the changes at the cellular and molecular levels do not always result in organismic or developmental changes. This apparent paradox is a current research challenge. In this paper, the main findings of gravity- and radiation-related research on higher plants are summarized, highlighting the knowledge gaps that are still necessary to fill. Existing experimental facilities to simulate the effect of space factors, as well as requirements for future facilities for possible experiments to achieve fundamental biology goals are considered. Finally, the need for making synergies among disciplines and for establishing global standard operating procedures for analyses and data collection in space experiments is highlighted

Proteins specifically identified in one extraction fraction and common to the three gravity conditions (i.e. 1 g ground, 1 g space and µg space).

<p>Blue bars indicate the total number of proteins identified. Red bars show the number of proteins with at least one transmembrane segment and the green bars the number of proteins which are annotated as “membrane” in Gene Ontology (The number of proteins is indicated at the top of the bars).</p

Schematic view of the experiment scenario of Arabidopsis culture on board the ISS.

<p>Schematic view of the experiment scenario of Arabidopsis culture on board the ISS.</p

Workflow of microsome preparation and sequential extraction of proteins with salts and detergents.

<p>¹ Volumes of buffer are expressed as µl per mg of initial fresh material used. * Centrifugation 100 000 g, 20 min; ** Centrifugation 15 000 g 15 min.</p

Design and views of the culture chamber and of the experiment container used during the GENARA-A experiment.

<p>(A, C) View of a culture chamber, B. View of an experiment container housing four culture chambers. The grey part on the scheme corresponds to the filter pad with a nylon mesh sewed on top (A). Empty culture chamber (C-left) and closed culture chamber with the Biofoil (C-right). (Adapted from the Space Biology Product Catalog of ASTRIUM company).</p