Fluid dynamics during Random Positioning Machine micro-gravity experiments

Leguy, Cad Carole; Delfos, R.; Pourquié, Mathieu; Poelma, Christian; Westerweel, J.; Loon, Jack J. W. A. van

doi:10.1016/j.asr.2017.03.009

Cited by 17 publications

(17 citation statements)

References 35 publications

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“… 40 , 41 However, one should take note of increased fluid movements if such a system is used for, e.g., cell cultures experiments. 42 – 44 For regular RPM studies it is important to place the sample as close as possible to the center of rotation in order to minimize residual g artifacts. 20 , 45 However, in the partial- g RPM HW we want to have a rotating disk as large as possible to minimize centrifuge associated artifacts like the aforementioned sample gravity gradients.…”

Section: Discussionmentioning

confidence: 99%

Novel, Moon and Mars, partial gravity simulation paradigms and their effects on the balance between cell growth and cell proliferation during early plant development

et al. 2018

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Clinostats and Random Positioning Machine (RPM) are used to simulate microgravity, but, for space exploration, we need to know the response of living systems to fractional levels of gravity (partial gravity) as they exist on Moon and Mars. We have developed and compared two different paradigms to simulate partial gravity using the RPM, one by implementing a centrifuge on the RPM (RPMHW), the other by applying specific software protocols to driving the RPM motors (RPMSW). The effects of the simulated partial gravity were tested in plant root meristematic cells, a system with known response to real and simulated microgravity. Seeds of Arabidopsis thaliana were germinated under simulated Moon (0.17 g) and Mars (0.38 g) gravity. In parallel, seeds germinated under simulated microgravity (RPM), or at 1 g control conditions. Fixed root meristematic cells from 4-day grown seedlings were analyzed for cell proliferation rate and rate of ribosome biogenesis using morphometrical methods and molecular markers of the regulation of cell cycle and nucleolar activity. Cell proliferation appeared increased and cell growth was depleted under Moon gravity, compared with the 1 g control. The effects were even higher at the Moon level than at simulated microgravity, indicating that meristematic competence (balance between cell growth and proliferation) is also affected at this gravity level. However, the results at the simulated Mars level were close to the 1 g static control. This suggests that the threshold for sensing and responding to gravity alteration in the root would be at a level intermediate between Moon and Mars gravity. Both partial g simulation strategies seem valid and show similar results at Moon g-levels, but further research is needed, in spaceflight and simulation facilities, especially around and beyond Mars g levels to better understand more precisely the differences and constrains in the use of these facilities for the space biology community.

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Section: Discussionmentioning

confidence: 99%

Novel, Moon and Mars, partial gravity simulation paradigms and their effects on the balance between cell growth and cell proliferation during early plant development

et al. 2018

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“…Nevertheless, in gravity-perceiving root columella cells, the position of amyloplasts was similar in weightlessness in spaceflight and on the RPM, but was significantly different between spaceflight and two-axial clinostats ( Figure 5 ). For in vitro systems like Arabidopsis cell cultures, it is important to realize that in fluid-filled experimental containers, there is also a fluid shear applied to the cells (Leguy et al, 2017). This issue can be mitigated by increasing the cell substrate viscosity (Kamal et al, 2019).…”

Section: Clinostatsmentioning

confidence: 99%

Comparison of Microgravity Analogs to Spaceflight in Studies of Plant Growth and Development

et al. 2019

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Life on Earth has evolved under the influence of gravity. This force has played an important role in shaping development and morphology from the molecular level to the whole organism. Although aquatic life experiences reduced gravity effects, land plants have evolved under a 1-g environment. Understanding gravitational effects requires changing the magnitude of this force. One method of eliminating gravity'’s influence is to enter into a free-fall orbit around the planet, thereby achieving a balance between centripetal force of gravity and the centrifugal force of the moving object. This balance is often mistakenly referred to as microgravity, but is best described as weightlessness. In addition to actually compensating gravity, instruments such as clinostats, random-positioning machines (RPM), and magnetic levitation devices have been used to eliminate effects of constant gravity on plant growth and development. However, these platforms do not reduce gravity but constantly change its direction. Despite these fundamental differences, there are few studies that have investigated the comparability between these platforms and weightlessness. Here, we provide a review of the strengths and weaknesses of these analogs for the study of plant growth and development compared to spaceflight experiments. We also consider reduced or partial gravity effects via spaceflight and analog methods. While these analogs are useful, the fidelity of the results relative to spaceflight depends on biological parameters and environmental conditions that cannot be simulated in ground-based studies.

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“…The 1g control experiment was performed with similar samples attached to the static part of the RPM, for the control cells to be subjected to the same environmental temperature and residual vibration forces as the samples grown in the RPM rotating part of the instrument. The fluid motion effects related to the rotation should be nihil, since the cells are immobilized in agarose, just with this purpose [33].…”

Section: Microgravity Simulator and Experimental Designmentioning

confidence: 99%

Differential transcriptional profile through cell cycle progression in Arabidopsis cultures under simulated microgravity

et al. 2019

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Plant cell proliferation is affected by microgravity during spaceflight, but involved molecular mechanisms, key for space agronomy goals, remain unclear. To investigate transcriptomic changes in cell cycle phases caused by simulated microgravity, an Arabidopsis immobilized synchronous suspension culture was incubated in a Random Positioning Machine. After simulation, a transcriptomic analysis was performed with two subpopulations of cells (G2/M and G1 phases enriched) and an asynchronous culture sample. Differential expression was found at cell proliferation, energy/redox and stress responses, plus unknown biological processes gene ontology groups. Overall expression inhibition was a common response to simulated microgravity, but differences peak at the G2/M phase and stress response components change dramatically from G2/M to the G1 subpopulation suggesting a differential adaptation response to simulated microgravity through the cell cycle. Cell cycle adaptation using both known stress mechanisms and unknown function genes may cope with reduced gravity as an evolutionary novel environment.

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Fluid dynamics during Random Positioning Machine micro-gravity experiments

Cited by 17 publications

References 35 publications

Novel, Moon and Mars, partial gravity simulation paradigms and their effects on the balance between cell growth and cell proliferation during early plant development

Novel, Moon and Mars, partial gravity simulation paradigms and their effects on the balance between cell growth and cell proliferation during early plant development

Comparison of Microgravity Analogs to Spaceflight in Studies of Plant Growth and Development

Differential transcriptional profile through cell cycle progression in Arabidopsis cultures under simulated microgravity

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