THE FINE STRUCTURE OF CHROMATIN IN PARANOSEMA GRYLLI (MICROSPORIDA)
N. N. Bobyleva, E. S. Nassonova, S. O. Skarlato 1
Institute of Cytology, RAS, St. Petersburg, Russia;
1 e-mail: sergei_skarlato@yahoo.com
Nucleosomes were found for the first time in the nuclear chromatin of Microsporida - organisms known among the
smallest eukaryotes on Earth. Chromatin of Paranosema grylli sporoplasm was studied by Miller's technique. On low
ionic-strength cell spreads, this chromatin was represented by 10 nm nucleosome filaments, 20 nm filaments, and "smooth"
(nucleosome-free) filaments of 3-4 nm in diameter. Nucleosome filaments display structural heterogeneity seen as irregular
arrangement of nucleosome particles along the filament length. Different nucleosome filaments show 13-30 nucleosomes per
1 μm with the length of linker DNA ranging from 10 to 45 nm. The present results suggest that microsporidian chromatin is
weakly condensed. Only lower-order chromatin packaging levels displayed some structural peculiarities.
Key words: chromatin, lower eukaryotes, microsporidia, nuclear apparatus, nucleosomes
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