Seed Germination and Seedling Growth under Simulated Microgravity Causes Alterations in Plant Cell Proliferation and Ribosome Biogenesis

  • Isabel Matía
  • Jack W. A. van Loon
  • Eugénie Carnero-Díaz
  • Roberto Marco
  • Francisco Javier Medina
Original Article


The study of the modifications induced by altered gravity in functions of plant cells is a valuable tool for the objective of the survival of terrestrial organisms in conditions different from those of the Earth. We have used the system “cell proliferation–ribosome biogenesis”, two inter-related essential cellular processes, with the purpose of studying these modifications. Arabidopsis seedlings belonging to a transformed line containing the reporter gene GUS under the control of the promoter of the cyclin gene CYCB1, a cell cycle regulator, were grown in a Random Positioning Machine, a device known to accurately simulate microgravity. Samples were taken at 2, 4 and 8 days after germination and subjected to biometrical analysis and cellular morphometrical, ultrastructural and immunocytochemical studies in order to know the rates of cell proliferation and ribosome biogenesis, plus the estimation of the expression of the cyclin gene, as an indication of the state of cell cycle regulation. Our results show that cells divide more in simulated microgravity in a Random Positioning Machine than in control gravity, but the cell cycle appears significantly altered as early as 2 days after germination. Furthermore, higher proliferation is not accompanied by an increase in ribosome synthesis, as is the rule on Earth, but the functional markers of this process appear depleted in simulated microgravity-grown samples. Therefore, the alteration of the gravitational environmental conditions results in a considerable stress for plant cells, including those not specialized in gravity perception.


Altered gravity Random positioning machine Cell cycle Nucleolus Root meristematic cells GUS assay Electron microscopy 


  1. Centis-Aubay, S., Gasset, G., Mazars, C., Ranjeva, R., Graziana, A.: Changes in gravitational forces induce modifications of gene expression in A. thaliana seedlings. Planta 218, 179–185 (2003)CrossRefGoogle Scholar
  2. Dewitte, W., Murray, J.A.H.: The plant cell cycle. Annu. Rev. Plant Biol. 54, 235–264 (2003)CrossRefGoogle Scholar
  3. Ferreira, P., Hemerly, A.S., De Almeida Engler, J., Bergounioux, C., Burssens, S., Van Montagu, M., Engler, G., Inzé, D.: Three discrete classes of Arabidopsis cyclins are expressed during different intervals of the cell cycle. Proc. Natl. Acad. Sci. U. S. A. 91, 11313–11317 (1994)CrossRefGoogle Scholar
  4. González-Camacho, F., Medina, F.J.: The nucleolar structure and nucleolar proteins as indicators of cell proliferation events in plants. J. Appl. Biomed. 3, 167–174 (2005)Google Scholar
  5. Jefferson, R.A., Kavanagh, T.A., Beva, M.W.: GUS fusions: β-glucuronidase as a sensitive and versatile gene fusion marker in higher plants. EMBO J. 6, 3901–3907 (1987)Google Scholar
  6. Klein, J., Grummt, I.: Cell cycle-dependent regulation of RNA polymerase I transcription: the nucleolar transcription factor UBF is inactive in mitosis and early G1. Proc. Natl. Acad. Sci. U. S. A. 96, 6096–6101 (1999)CrossRefGoogle Scholar
  7. Kordyum, E.L.: Biology of plant cells in microgravity and under clinostating. Int. Rev. Cytol. 171, 1–78 (1997)CrossRefGoogle Scholar
  8. Matía, I., González-Camacho, F., Marco, R., Kiss, J.Z., Gasset, G., Medina, F.J.: Nucleolar structure and proliferation activity of Arabidopsis root cells from seedlings germinated on the International Space Station. Adv. Space Res. 36, 1244–1253 (2005)CrossRefGoogle Scholar
  9. Matía, I., González-Camacho, F., Marco, R., Kiss, J.Z., Gasset, G., van Loon, J.W.A., Medina, F.J.: The “Root” experiment of the “Cervantes” Spanish Soyuz Mission: cell proliferation and nucleolar activity alterations in Arabidopsis roots germinated in real or simulated microgravity. Microgr. Sci. Technol. 19, 128–132 (2007)CrossRefGoogle Scholar
  10. Medina, F.J., Cerdido, A., De Cárcer, G.: The functional organization of the nucleolus in proliferating plant cells. Eur. J. Histochem. 44, 117–131 (2000)Google Scholar
  11. Morita, M.T., Tasaka, M.: Gravity sensing and signaling. Curr. Opin. Plant Biol. 7, 712–718 (2004)CrossRefGoogle Scholar
  12. Sáez-Vásquez, J., Caparros-Ruiz, D., Barneche, F., Echeverría, M.: A plant snoRNP complex containing snoRNAs, fibrillarin, and nucleolin-like proteins is competent for both rRNA gene binding and pre-rRNA processing in vitro. Mol. Cell Biol. 24, 7284–7297 (2004)CrossRefGoogle Scholar
  13. Sobol, M., González-Camacho, F., Rodríguez-Vilariño, V., Kordyum, E., Medina, F.J.: Subnucleolar location of fibrillarin and NopA64 in Lepidium sativum root meristematic cells is changed in altered gravity. Protoplasma 228, 209–219 (2006)CrossRefGoogle Scholar
  14. Sugimoto-Shirasu, K., Roberts, K.: “Big it up”: endoreduplication and cell-size control in plants. Curr. Opin. Plant Biol. 6, 544–553 (2003)CrossRefGoogle Scholar
  15. Testillano, P.S., González-Melendi, P., Ahmadian, P., Risueño, M.C.: The methylation–acetylation method: an ultrastructural cytochemistry for nucleic acids compatible with immunogold studies. J. Struct. Biol. 114, 123–139 (1995)CrossRefGoogle Scholar
  16. van Loon, J.W.A.: Some history and use of the random positioning machine, RPM, in gravity related research. Adv. Space Res. 39, 1161–1165 (2007)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Isabel Matía
    • 1
  • Jack W. A. van Loon
    • 2
  • Eugénie Carnero-Díaz
    • 3
  • Roberto Marco
    • 4
  • Francisco Javier Medina
    • 1
  1. 1.Centro de Investigaciones Biológicas (CSIC)MadridSpain
  2. 2.DESC, ACTA- Dept Oral Cell BiologyVrije UniversiteitAmsterdamThe Netherlands
  3. 3.CEMVUniversité Pierre et Marie CurieParis VIFrance
  4. 4.Departamento de Bioquímica-IIB (UAM-CSIC)MadridSpain

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