Plastid position in Arabidopsis columella cells is similar in microgravity and on a random-positioning machine

Abstract

In order to study gravity effects on plant structure and function, it may become necessary to remove the g-stimulus. On Earth, various instruments such as clinostats have been used by biologists in an attempt to neutralize the effects of gravity. In this study, the position of amyloplasts was assayed in columella cells in the roots of Arabidopsis thaliana (L.) Heynh. seedlings grown in the following conditions: on Earth, on a two-dimensional clinostat at 1 rpm, on a three-dimensional clinostat (also called a random-positioning machine, or an RPM), and in space (true microgravity). In addition, the effects of these gravity treatments on columella cell area and plastid area also were measured. In terms of the parameters measured, only amyloplast position was affected by the gravity treatments. Plastid position was not significantly different between spaceflight and RPM conditions but was significantly different between spaceflight and the classical two-dimensional clinostat treatments. Flanking columella cells showed a greater susceptibility to changes in gravity compared to the central columella cells. In addition, columella cells of seedlings that were grown on the RPM did not exhibit deleterious effects in terms of their ultrastructure as has been reported previously for seedlings grown on a two-dimensional clinostat. This study supports the hypothesis that the RPM provides a useful simulation of weightlessness.

The Onset of Gravisensitivity in the Embryonic Root of Flax

“…However, clinorotation does not hinder the formative stages of the gravisensory apparatus, nor is the detrimental effect of clinorotation universal (Kraft et al, 2000). Our investigations show that clinostats, in addition to their classical role of averaging gravity effects, can provide mechanostimulation based on rate and duration of rotation and thus may be useful for studies of cellular apoptosis and tissue repair processes.…”

Chronic exposure to simulated space conditions predominantly affects cytoskeleton remodeling and oxidative stress response in mouse fetal fibroblasts

“…Genome-wide gene expression changes were thereafter assessed by microarrays. For microgravity simulation, we used the random positioning machine (RPM), which is one of the most widely used instruments for this purpose and has proven valuable in many cell types (1)(2)(3)(4)(5)(6). As far as cosmic radiation is concerned, simulating the wide variety of ions ranging from low to very high energies encountered in space is problematic, particularly if irradiation is combined with microgravity simulation models.…”

Technology and Developments for the Random Positioning Machine, RPM

“…The objects in such a clinostat experience gravity continuously rotating in one vertical plane. Especially for larger objects it was recognized that the 3D random rotation could provide a better simulation of the weightlessness conditions as compared to the classical 2D clinostat (Kraft et al 2000).…”