Electron microscopic evidence for the circular form of RNA in the cytoplasm of eukaryotic cells

  title={Electron microscopic evidence for the circular form of RNA in the cytoplasm of eukaryotic cells},
  author={Ming-Ta Hsu and Miguel Coca‐Prados},
LINEAR single-stranded RNA genomes extracted from several RNA viruses were found to exist in a circular conformation when examined in the electron microscope in partially denaturing conditions1–4. The circular conformation of viral RNA presumably arises from base pairing between RNA sequences at the two ends of the RNA molecules. The biological significance of the circular structure of single-stranded RNA is still unknown. Here we report the observation of the circular form of RNA extracted… 
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RNA metabolism in the HeLa cell nucleus.
  • S. Penman
  • Biology
    Journal of molecular biology
  • 1966
Electron Microscope Analysis of Partial Denaturation of F Factor Deoxyribonucleic Acid
  • M. Hsu
  • Biology, Chemistry
    Journal of bacteriology
  • 1974
Partial denaturation pattern of sex factor deoxyribonucleic acid of Escherichia coli was studied by electron microscopy. Clustering of the adenine-plusthymine-rich regions in one part of the molecule
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The viroid of the potato spindle tuber disease is a covalently closed ring of 359 ribonucleotides that is the first pathogen of a eukaryotic organism for which the complete molecular structure has been established.
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