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

Abstract

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.

Keywords

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

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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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