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Dynamic changes in microtubule organization during division of the primitive dinoflagellate Oxyrrhis marina
Author(s) -
Kato Koichi H.,
Moriyama Akihiko,
Itoh Tomohiko J.,
Yamamoto Masayuki,
Horio Tetsuya,
Huitorel Philippe
Publication year - 2000
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(00)01106-0
Subject(s) - microtubule , biology , astral microtubules , nucleus , flagellum , microtubule organizing center , anatomy , basal body , cell cortex , metaphase , microbiology and biotechnology , cell division , cytoskeleton , centrosome , spindle apparatus , cell , chromosome , cell cycle , paleontology , biochemistry , genetics , bacteria , gene
Summry— The marine dinoflagellate Oxyrrhis marina has three major microtubular systems: the flagellar apparatus made of one transverse and one longitudinal flagella and their appendages, cortical microtubules, and intranuclear microtubules. We investigated the dynamic changes of these microtubular systems during cell division by transmission and scanning electron microscopy, and confocal fluorescent laser microscopy. During prophase, basal bodies, both flagella and their appendages were duplicated. In the round nucleus situated in the cell centre, intranuclear microtubules appeared radiating toward the centre of the nucleus from densities located in some nuclear pores. During metaphase, both daughter flagellar apparatus separated and moved apart along the main cell axis. Microtubules of ventral cortex were also duplicated and moved with the flagellar apparatus. The nucleus flattened in the longitudinal direction and became discoid‐shaped close to the equatorial plane. Many bundles of microtubules ran parallel to the short axis of the nucleus (cell long axis), between which chromosomes were arranged in the same direction. During ana—telophase, the nucleus elongated along the longitudinal axis and took a dumbbell shape. At this stage a contractile ring containing actin was clearly observed in the equatorial cortex. The cortical microtubule network seemed to be cut into two halves at the position of the actin bundle. Shortly after, the nucleus divided into two nuclei, then the cell body was constricted at its equator and divided into one anterior and one posterior halves which were soon rebuilt to produce two cells with two full sets of cortical microtubules. From our observations, several mechanisms for the duplication of the microtubule networks during mitosis in O. marina are discussed.