Microscopy and Microanalysis



BIOLOGICAL APPLICATIONS

The Distribution of Light Elements in Biological Cells Measured by Electron Probe X-Ray Microanalysis of Cryosections


Karl  Zierold  a1 , Jean  Michel  a2 c1 , Christine  Terryn  a2 and Gérard  Balossier  a2
a1 Max-Planck-Institute of Molecular Physiology, 44227 Dortmund, Germany
a2 INSERM ERM 203, University of Reims, 51685 Reims, France

Article author query
zierold k   [PubMed][Google Scholar] 
michel j   [PubMed][Google Scholar] 
terryn c   [PubMed][Google Scholar] 
balossier g   [PubMed][Google Scholar] 

Abstract

The intracellular distribution of the elements carbon, nitrogen, and oxygen was measured in cultured rat hepatocytes by energy dispersive electron probe X-ray microanalysis of 100-nm-thick freeze-dried cryosections. Electron irradiation with a dose up to 106 e/nm2 caused no or merely negligible mass loss in mitochondria and in cytoplasm. Cell nuclei lost carbon, nitrogen, and—to a clearly higher extent—oxygen with increasing electron irradiation. Therefore, electron doses less than 3 × 105 e/nm2 were used to measure the subcellular compartmentation of carbon, nitrogen, and oxygen in cytoplasm, mitochondria, and nuclei of the cells. The subcellular distribution of carbon, nitrogen, and oxygen reflects the intracellular compartmentation of various biomolecules. Cells exposed to inorganic mercury before cryofixation showed an increase of oxygen in nuclei and cytoplasm. Concomitantly the phosphorus/nitrogen ratio decreased in mitochondria. The data suggest mercury-induced production of ribonucleic acid (RNA) and decrease of adenosine triphosphate (ATP). Although biomolecules cannot be identified by X-ray microanalysis, measurements of the whole element spectrum including the light elements carbon, nitrogen, and oxygen can be useful to study specific biomolecular activity in cellular compartments depending on the functional state of the cell.

(Received November 21 2003)
(Accepted June 11 2004)


Key Words: cryosection; hepatocyte; light elements; mercury cytotoxicity; radiation damage; X-ray microanalysis.

Correspondence:
c1 Corresponding author. E-mail: jean.michel@univ-reims.fr