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Colocalization of the cyclin B homologue P56 and β‐tubulin during the cell cycle in a unicellular eucaryote dinoflagellate
Author(s) -
Barbier Michèle,
Géraud MarieLine,
Nicolas Gisèle,
SoyerGobillard MarieOdile
Publication year - 1998
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1016/s0248-4900(98)80233-5
Subject(s) - colocalization , biology , dinoflagellate , tubulin , microbiology and biotechnology , cell cycle , cyclin , microtubule , cell , biochemistry , botany
We provide evidence for an unusual behavior of the cyclin B homologue, p56, in the dinoflagellate Crypthecodinium cohnii. p56, of which we previously demonstrated the presence in this original eukaryotic protist, is present all along the cell cycle progression, and is exclusively cytoplasmic as revealed after immunofluorescence labeling with anti‐p56 Ab and counterstaining with Dapi. It was never found in the nucleus as is the case in higher eukaryotic cells. During motosis, p56 was essentially associated with the mitotic apparatus: centrosomes and mitotic spindle, as shown after double immunofluorescence labeling with anti p56 and anti β‐tubulin Ab. Using high pressure freeze fixation, we clearly detected in transmission electron microscopy (TEM) the localization of p56 cyclin B homologue and β‐tubulin: single immunogold labeling demonstrated that p56 is localized along the whole cell cortex, along the cleavage furrow of anaphase to cytokinesis cells and into cytoplasmic channels passing throughout the mitotic nucleus where is located the mitotic spindle. Double immunogold labeling realized with anti‐p56 and anti‐β‐tubulin antibodies confirm that p56 antigens colocalize with β‐tubulin in many sites. The significance of the exclusively cytoplasmic localization of the cyclin B homologue is discussed.