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Dinokaryon
Type of nucleus seen in many dinoflagellates / From Wikipedia, the free encyclopedia
A dinokaryon is a eukaryotic nucleus present in dinoflagellates in which the chromosomes are fibrillar in appearance (i.e. with unmasked DNA fibrils) and are more or less continuously condensed.
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The nuclear envelope does not break down during mitosis, which is thus termed closed mitosis, or "dinomitosis".[1] The mitotic spindle is extranuclear.[2]
Histones are absent.[3] However, recent EST sequencing has revealed the presence of histones in one of the closest relative to dinoflagellates, Perkinsus marinus and an early-branching dinoflagellate, Hematodinium sp.[4] However, histone-like proteins of bacterial origins are found in the coding regions at periphery of the dinokaryon's chromosomes.[5]