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6th ESACP Congress, Heidelberg, April 7-11, 1999 |
A083
3D localization of nucleolin, an rRNA maturation nucleolar protein, was
studied during interphase and mitosis in human KB cells, using confocal
microscopy and volume rendering visualization. Its localization was compared
to that of DNA and UBF (Upstream Binding Factor), which remains associated
to rDNA genes throughout the cell cycle. During interphase, the nucleolin
labeling was localized in structures forming networks in the nucleoli and
was essentially not colocalized with UBF which was present in numerous
necklace structures. During prophase, the network organization of the
nucleolin labeling was lost and this protein was present in large remnants
of homogeneous aspect. These nucleolar remnants were thereafter expelled at
the periphery of the metaphase plate, where they progressively desagregated
in numerous cytoplasmic granules and a faint perichromosomic labeling. At
this step, nucleolin was not detected in the NORs in contrast to UBF. During
telophase, some cytoplasmic granules were found in close contact with
prenuclei surface, even forming connections with intranuclear nucleolin
already present in prenucleolar bodies (PNBs). Some of the PNBs were
associated with NORs i.e. with UBF. In conclusion, during the cell cycle,
nucleolin has a localization similar to other maturation-associated proteins,
whose behaviour is totally different from that of transcription associated
proteins.
THREE-DIMENSIONAL COLOCALIZATION OF NUCLEOLIN, UBF AND DNA DURING
INTERPHASE AND MITOSIS: A STUDY USING CONFOCAL MICROSCOPY AND VOLUME
RENDERING
Klein C, Cheutin T, O'Donohue MF, Kaplan H, Lucas L, Ploton D
Unité Médian, EA 2063, IFR 53, Reims, France