How to obtain an integrated picture of the molecular networks involved in adaptation to microgravity in different biological systems?

Periodically, the European Space Agency (ESA) updates scientific roadmaps in consultation with the scientific community. The ESA SciSpacE Science Community White Paper (SSCWP) 9, "Biology in Space and Analogue Environments", focusses in 5 main topic areas, aiming to address key community-identified knowledge gaps in Space Biology. Here we present one of the identified topic areas, which is also an unanswered question of life science research in Space: "How to Obtain an Integrated Picture of the Molecular Networks Involved in Adaptation to Microgravity in Different Biological Systems?" The manuscript reports the main gaps of knowledge which have been identified by the community in the above topic area as well as the approach the community indicates to address the gaps not yet bridged. Moreover, the relevance that these research activities might have for the space exploration programs and also for application in industrial and technological fields on Earth is briefly discussed.

How are cell and tissue structure and function influenced by gravity and what are the gravity perception mechanisms?

Progress in mechanobiology allowed us to better understand the important role of mechanical forces in the regulation of biological processes. Space research in the field of life sciences clearly showed that gravity plays a crucial role in biological processes. The space environment offers the unique opportunity to carry out experiments without gravity, helping us not only to understand the effects of gravitational alterations on biological systems but also the mechanisms underlying mechanoperception and cell/tissue response to mechanical and gravitational stresses. Despite the progress made so far, for future space exploration programs it is necessary to increase our knowledge on the mechanotransduction processes as well as on the molecular mechanisms underlying microgravity-induced cell and tissue alterations. This white paper reports the suggestions and recommendations of the SciSpacE Science Community for the elaboration of the section of the European Space Agency roadmap "Biology in Space and Analogue Environments" focusing on "How are cells and tissues influenced by gravity and what are the gravity perception mechanisms?" The knowledge gaps that prevent the Science Community from fully answering this question and the activities proposed to fill them are discussed.

How do gravity alterations affect animal and human systems at a cellular/tissue level?

The present white paper concerns the indications and recommendations of the SciSpacE Science Community to make progress in filling the gaps of knowledge that prevent us from answering the question: "How Do Gravity Alterations Affect Animal and Human Systems at a Cellular/Tissue Level?" This is one of the five major scientific issues of the ESA roadmap "Biology in Space and Analogue Environments". Despite the many studies conducted so far on spaceflight adaptation mechanisms and related pathophysiological alterations observed in astronauts, we are not yet able to elaborate a synthetic integrated model of the many changes occurring at different system and functional levels. Consequently, it is difficult to develop credible models for predicting long-term consequences of human adaptation to the space environment, as well as to implement medical support plans for long-term missions and a strategy for preventing the possible health risks due to prolonged exposure to spaceflight beyond the low Earth orbit (LEO). The research activities suggested by the scientific community have the aim to overcome these problems by striving to connect biological and physiological aspects in a more holistic view of space adaptation effects.

Perspectives for plant biology in space and analogue environments.

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.

Enhancing European capabilities for application of multi-omics studies in biology and biomedicine space research.

Following on from the NASA twins' study, there has been a tremendous interest in the use of omics techniques in spaceflight. Individual space agencies, NASA's GeneLab, JAXA's ibSLS, and the ESA-funded Space Omics Topical Team and the International Standards for Space Omics Processing (ISSOP) groups have established several initiatives to support this growth. Here, we present recommendations from the Space Omics Topical Team to promote standard application of space omics in Europe. We focus on four main themes: i) continued participation in and coordination with international omics endeavors, ii) strengthening of the European space omics infrastructure including workforce and facilities, iii) capitalizing on the emerging opportunities in the commercial space sector, and iv) capitalizing on the emerging opportunities in human subjects research.

A Delphi study to identify and assess professional competencies in the education of optometrists

Purpose: The aim of this study was to identify, assess, and reach a consensus on the professional competencies that optometrists must acquire during their undergraduate training at the University of Valladolid. The results obtained may be useful in the revision of the current curriculum.MethodsA three round Delphi study was carried out with the participation of 116 participants grouped in 7 panels. In the first round, competencies were identified through an open-ended question and their frequency calculated. In the successive 2nd and 3rd rounds, the consensus and stability of each competency was established.ResultsA total of 56 professional competencies were identified, with 43 of them (77%) achieving a consensus among participants, of which the highest scores were obtained by the competencies that correspond to health functions of primary visual care. Out of the 13 competencies without consensus, for 11 of them this was due to the significant differences in assessment among the consulted participants; for 8 competencies (14%) response stability was found, while neither consensus nor stability were reached in 5 (9%) of the identified competencies.ConclusionsThe results obtained with this Delphi study provide a set of relevant competencies for updating the curriculum of the university Degree in Optics and Optometry at the University of Valladolid, improving its suitability to current and future professional reality. (AU)

Meta-analysis of the space flight and microgravity response of the Arabidopsis plant transcriptome.

Spaceflight presents a multifaceted environment for plants, combining the effects on growth of many stressors and factors including altered gravity, the influence of experiment hardware, and increased radiation exposure. To help understand the plant response to this complex suite of factors this study compared transcriptomic analysis of 15 Arabidopsis thaliana spaceflight experiments deposited in the National Aeronautics and Space Administration's GeneLab data repository. These data were reanalyzed for genes showing significant differential expression in spaceflight versus ground controls using a single common computational pipeline for either the microarray or the RNA-seq datasets. Such a standardized approach to analysis should greatly increase the robustness of comparisons made between datasets. This analysis was coupled with extensive cross-referencing to a curated matrix of metadata associated with these experiments. Our study reveals that factors such as analysis type (i.e., microarray versus RNA-seq) or environmental and hardware conditions have important confounding effects on comparisons seeking to define plant reactions to spaceflight. The metadata matrix allows selection of studies with high similarity scores, i.e., that share multiple elements of experimental design, such as plant age or flight hardware. Comparisons between these studies then helps reduce the complexity in drawing conclusions arising from comparisons made between experiments with very different designs.

A Delphi study to identify and assess professional competencies in the education of optometrists.

PURPOSE: The aim of this study was to identify, assess, and reach a consensus on the professional competencies that optometrists must acquire during their undergraduate training at the University of Valladolid. The results obtained may be useful in the revision of the current curriculum. METHODS: A three round Delphi study was carried out with the participation of 116 participants grouped in 7 panels. In the first round, competencies were identified through an open-ended question and their frequency calculated. In the successive 2nd and 3rd rounds, the consensus and stability of each competency was established. RESULTS: A total of 56 professional competencies were identified, with 43 of them (77%) achieving a consensus among participants, of which the highest scores were obtained by the competencies that correspond to health functions of primary visual care. Out of the 13 competencies without consensus, for 11 of them this was due to the significant differences in assessment among the consulted participants; for 8 competencies (14%) response stability was found, while neither consensus nor stability were reached in 5 (9%) of the identified competencies. CONCLUSIONS: The results obtained with this Delphi study provide a set of relevant competencies for updating the curriculum of the university Degree in Optics and Optometry at the University of Valladolid, improving its suitability to current and future professional reality.

Challenges and considerations for single-cell and spatially resolved transcriptomics sample collection during spaceflight.

Single-cell RNA sequencing (scRNA-seq) and spatially resolved transcriptomics (SRT) have experienced rapid development in recent years. The findings of spaceflight-based scRNA-seq and SRT investigations are likely to improve our understanding of life in space and our comprehension of gene expression in various cell systems and tissue dynamics. However, compared to their Earth-based counterparts, gene expression experiments conducted in spaceflight have not experienced the same pace of development. Out of the hundreds of spaceflight gene expression datasets available, only a few used scRNA-seq and SRT. In this perspective piece, we explore the growing importance of scRNA-seq and SRT in space biology and discuss the challenges and considerations relevant to robust experimental design to enable growth of these methods in the field.

Routine omics collection is a golden opportunity for European human research in space and analog environments.

Widespread generation and analysis of omics data have revolutionized molecular medicine on Earth, yet its power to yield new mechanistic insights and improve occupational health during spaceflight is still to be fully realized in humans. Nevertheless, rapid technological advancements and ever-regular spaceflight programs mean that longitudinal, standardized, and cost-effective collection of human space omics data are firmly within reach. Here, we consider the practicality and scientific return of different sampling methods and omic types in the context of human spaceflight. We also appraise ethical and legal considerations pertinent to omics data derived from European astronauts and spaceflight participants (SFPs). Ultimately, we propose that a routine omics collection program in spaceflight and analog environments presents a golden opportunity. Unlocking this bright future of artificial intelligence (AI)-driven analyses and personalized medicine approaches will require further investigation into best practices, including policy design and standardization of omics data, metadata, and sampling methods.

Red Light Enhances Plant Adaptation to Spaceflight and Mars g-Levels.

Understanding how plants respond and adapt to extraterrestrial conditions is essential for space exploration initiatives. Deleterious effects of the space environment on plant development have been reported, such as the unbalance of cell growth and proliferation in the root meristem, or gene expression reprogramming. However, plants are capable of surviving and completing the seed-to-seed life cycle under microgravity. A key research challenge is to identify environmental cues, such as light, which could compensate the negative effects of microgravity. Understanding the crosstalk between light and gravity sensing in space was the major objective of the NASA-ESA Seedling Growth series of spaceflight experiments (2013-2018). Different g-levels were used, with special attention to micro-g, Mars-g, and Earth-g. In spaceflight seedlings illuminated for 4 days with a white light photoperiod and then photostimulated with red light for 2 days, transcriptomic studies showed, first, that red light partially reverted the gene reprogramming induced by microgravity, and that the combination of microgravity and photoactivation was not recognized by seedlings as stressful. Two mutant lines of the nucleolar protein nucleolin exhibited differential requirements in response to red light photoactivation. This observation opens the way to directed-mutagenesis strategies in crop design to be used in space colonization. Further transcriptomic studies at different g-levels showed elevated plastid and mitochondrial genome expression in microgravity, associated with disturbed nucleus-organelle communication, and the upregulation of genes encoding auxin and cytokinin hormonal pathways. At the Mars g-level, genes of hormone pathways related to stress response were activated, together with some transcription factors specifically related to acclimation, suggesting that seedlings grown in partial-g are able to acclimate by modulating genome expression in routes related to space-environment-associated stress.

Building the Space Omics Topical Team to boost European space researchers' role in the international consortia redefining spaceflight-generated datasets.

In a broadening and more competitive space exploration landscape, playing at scale is necessary to obtain results. European researchers share their lessons learned on growing a research program where omics techniques can feed new knowledge, both fundamental and practical, for space exploration. Sending people to new space destinations will require interdisciplinary research centered around omics and personalized medicine, with added constraints of low-gravity and high-radiation environments.

Recent transcriptomic studies to elucidate the plant adaptive response to spaceflight and to simulated space environments.

Discovering the adaptation mechanisms of plants to the space environment is essential for supporting human space exploration. Transcriptomic analyses allow the identification of adaptation response pathways by detecting changes in gene expression at the global genome level caused by the main factors of the space environment, namely altered gravity and cosmic radiation. This article reviews transcriptomic studies carried out from plants grown in spaceflights and in different ground-based microgravity simulators. Despite differences in plant growth conditions, these studies have shown that cell wall remodeling, oxidative stress, defense response, and photosynthesis are common altered processes in plants grown under spaceflight conditions. European scientists have significantly contributed to the acquisition of this knowledge, e.g., by showing the role of red light in the adaptation response of plants (EMCS experiments) and the mechanisms of cellular response and adaptation mostly affecting cell cycle regulation, using cell cultures in microgravity simulators.

Space omics research in Europe: Contributions, geographical distribution and ESA member state funding schemes.

The European research community, via European Space Agency (ESA) spaceflight opportunities, has significantly contributed toward our current understanding of spaceflight biology. Recent molecular biology experiments include "omic" analysis, which provides a holistic and systems level understanding of the mechanisms underlying phenotypic adaptation. Despite vast interest in, and the immense quantity of biological information gained from space omics research, the knowledge of ESA-related space omics works as a collective remains poorly defined due to the recent exponential application of omics approaches in space and the limited search capabilities of pre-existing records. Thus, a review of such contributions is necessary to clarify and promote the development of space omics among ESA and ESA state members. To address this gap, in this review, we i) identified and summarized omics works led by European researchers, ii) geographically described these omics works, and iii) highlighted potential caveats in complex funding scenarios among ESA member states.

Spaceflight studies identify a gene encoding an intermediate filament involved in tropism pathways.

We performed a series of experiments to study the interaction between phototropism and gravitropism in Arabidopsis thaliana as part of the Seedling Growth Project on the International Space Station. Red-light-based and blue-light-based phototropism were examined in microgravity and at 1g, a control that was produced by an on-board centrifuge. At the end of the experiments, seedlings were frozen and brought back to Earth for gene profiling studies via RNASeq methods. In this paper, we focus on five genes identified in these space studies by their differential expression in space: one involved in auxin transport and four others encoding genes for: a methyltransferase subunit, a transmembrane protein, a transcription factor for endodermis formation, and a cytoskeletal element (an intermediate filament protein). Time course studies using mutant strains of these five genes were performed for blue-light and red-light phototropism studies as well as for gravitropism assays on ground. Interestingly, all five of the genes had some effects on all the tropisms under the conditions studied. In addition, RT-PCR analyses examined expression of the five genes in wild-type seedlings during blue-light-based phototropism. Previous studies have supported a role of both microfilaments and microtubules in tropism pathways. However, the most interesting finding of the present space studies is that NFL, a gene encoding an intermediate filament protein, plays a role in phototropism and gravitropism, which opens the possibility that this cytoskeletal element modulates signal transduction in plants.

A novel device to study altered gravity and light interactions in seedling tropisms.

Long-duration space missions will need to rely on the use of plants in bio-regenerative life support systems (BLSSs) because these systems can produce fresh food and oxygen, reduce carbon dioxide levels, recycle metabolic waste, and purify water. In this scenario, the need for new experiments on the effects of altered gravity conditions on plant biological processes is increasing, and significant efforts should be devoted to new ideas aimed at increasing the scientific output and lowering the experimental costs. Here, we report the design of an easy-to-produce and inexpensive device conceived to analyze the effect of interaction between gravity and light on root tropisms. Each unit consisted of a polystyrene multi-slot rack with light-emitting diodes (LEDs), capable of holding Petri dishes and assembled with a particular filter-paper folding. The device was successfully used for the ROOTROPS (for root tropisms) experiment performed in the Large Diameter Centrifuge (LDC) and Random Positioning Machine (RPM) at ESA's European Space Research and Technology centre (ESTEC). During the experiments, four light treatments and six gravity conditions were factorially combined to study their effects on root orientation of Brassica oleracea seedlings. Light treatments (red, blue, and white) and a dark condition were tested under four hypergravity levels (20 g, 15 g, 10 g, 5 g), a 1 g control, and a simulated microgravity (RPM) condition. Results of validation tests showed that after 24 h, the assembled system remained unaltered, no slipping or displacement of seedlings occurred at any hypergravity treatment or on the RPM, and seedlings exhibited robust growth. Overall, the device was effective and reliable in achieving scientific goals, suggesting that it can be used for ground-based research on phototropism-gravitropism interactions. Moreover, the concepts developed can be further expanded for use in future spaceflight experiments with plants.

Use of Reduced Gravity Simulators for Plant Biological Studies.

Simulated microgravity and partial gravity research on Earth is a necessary complement to space research in real microgravity due to limitations of access to spaceflight. However, the use of ground-based facilities for reduced gravity simulation is far from simple. Microgravity simulation usually results in the need to consider secondary effects that appear in the generation of altered gravity. These secondary effects may interfere with gravity alteration in the changes observed in the biological processes under study. In addition to microgravity simulation, ground-based facilities are also capable of generating hypergravity or fractional gravity conditions whose effects on biological systems are worth being tested and compared with the results of microgravity exposure. Multiple technologies (2D clinorotation, random positioning machines, magnetic levitators, or centrifuges) and experimental hardware (different containers and substrates for seedlings or cell cultures) are available for these studies. Experimental requirements should be collectively and carefully considered in defining the optimal experimental design, taking into account that some environmental parameters, or life-support conditions, could be difficult to be provided in certain facilities. Using simulation facilities will allow us to anticipate, modify, or redefine the findings provided by the scarce available spaceflight opportunities.

Mammalian and Invertebrate Models as Complementary Tools for Gaining Mechanistic Insight on Muscle Responses to Spaceflight.

Bioinformatics approaches have proven useful in understanding biological responses to spaceflight. Spaceflight experiments remain resource intensive and rare. One outstanding issue is how to maximize scientific output from a limited number of omics datasets from traditional animal models including nematodes, fruitfly, and rodents. The utility of omics data from invertebrate models in anticipating mammalian responses to spaceflight has not been fully explored. Hence, we performed comparative analyses of transcriptomes of soleus and extensor digitorum longus (EDL) in mice that underwent 37 days of spaceflight. Results indicate shared stress responses and altered circadian rhythm. EDL showed more robust growth signals and Pde2a downregulation, possibly underlying its resistance to atrophy versus soleus. Spaceflight and hindlimb unloading mice shared differential regulation of proliferation, circadian, and neuronal signaling. Shared gene regulation in muscles of humans on bedrest and space flown rodents suggest targets for mitigating muscle atrophy in space and on Earth. Spaceflight responses of C. elegans were more similar to EDL. Discrete life stages of D. melanogaster have distinct utility in anticipating EDL and soleus responses. In summary, spaceflight leads to shared and discrete molecular responses between muscle types and invertebrate models may augment mechanistic knowledge gained from rodent spaceflight and ground-based studies.

Light signals counteract alterations caused by simulated microgravity in proliferating plant cells.

PREMISE: Light and gravity are fundamental cues for plant development. Our understanding of the effects of light stimuli on plants in space, without gravity, is key to providing conditions for plants to acclimate to the environment. Here we tested the hypothesis that the alterations caused by the absence of gravity in root meristematic cells can be counteracted by light. METHODS: Seedlings of wild-type Arabidopsis thaliana and two mutants of the essential nucleolar protein nucleolin (nuc1, nuc2) were grown in simulated microgravity, either under a white light photoperiod or under continuous darkness. Key variables of cell proliferation (cell cycle regulation), cell growth (ribosome biogenesis), and auxin transport were measured in the root meristem using in situ cellular markers and transcriptomic methods and compared with those of a 1 g control. RESULTS: The incorporation of a photoperiod regime was sufficient to attenuate or suppress the effects caused by gravitational stress at the cellular level in the root meristem. In all cases, values for variables recorded from samples receiving light stimuli in simulated microgravity were closer to values from the controls than values from samples grown in darkness. Differential sensitivities were obtained for the two nucleolin mutants. CONCLUSIONS: Light signals may totally or partially replace gravity signals, significantly improving plant growth and development in microgravity. Despite that, molecular alterations are still compatible with the expected acclimation mechanisms, which need to be better understood. The differential sensitivity of nuc1 and nuc2 mutants to gravitational stress points to new strategies to produce more resilient plants to travel with humans in new extraterrestrial endeavors.