Supranucleosomal organization of chromatin fibers in nuclei of Drosophila S2 cells.
Earlier, the interphase chromatin structures could not be visualized due to the stickiness of the nuclear material. We have reduced stickiness by the reversal of permeabilization allowing the isolation and microscopic imaging of interphase chromatin structures. By using a high resolution of synchronization, collecting 36 elutriation fractions, we show that major intermediates of chromatin condensation include: (a) decondensed veillike chromatin at the unset of the S phase (2.0-2.2 C-value), (b) polarization of veiled chromatin (2.2-2.6 C), (c) fibrous chromatin (2.6-3.0 C), chromatin bodies (3.0-3.3 C), early precondensed chromosomes (3.3-3.6). The compaction of Drosophila chromosomes did not reach that of the mammalian cells in the final stage of condensation (3.6-4.0 C). Drosophila chromosomes consist of smaller units called rodlets. Results demonstrate that nucleosomal chromatin ("beads on string") does not form a solenoid structure; rather, the topological arrangement consists of meandering and plectonemic loops.
Banfalvi
Gaspar
G
Department of Microbial Biotechnology and Cell Biology, University of Debrecen, Debrecen, Hungary. bgaspar@delfin.klte.hu
Trencsenyi
Gyorgy
G
Ujvarosi
Kinga
K
Nagy
Gabor
G
Ombodi
Timea
T
Bedei
Monika
M
Somogyi
Csilla
C
Basnakian
Alexei G
AG
D000818:Animals; D002453:Cell Cycle; D002460:Cell Line; D002467:Cell Nucleus / Q000648:ultrastructure*; D002843:Chromatin / Q000648:ultrastructure*; D004247:DNA / Q000096:biosynthesis; D004331:Drosophila melanogaster / Q000166:cytology / Q000648:ultrastructure*; D008958:Models, Molecular; D009707:Nucleosomes / Q000648:ultrastructure
D002843:Chromatin; D009707:Nucleosomes; D004247:DNA