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Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net.

ABSTRACT: Dinoflagellates are some of the most common eukaryotic cells in the ocean, but have very unusual nuclei. Many exhibit a form of closed mitosis (dinomitosis) wherein the nuclear envelope (NE) invaginates to form one or more trans-nuclear tunnels. Rather than contact spindles directly, the chromatids then bind to membrane-based kinetochores on the NE. To better understand these unique mitotic features, we reconstructed the nuclear architecture of Polykrikos kofoidii in 3D using focused ion beam scanning electron microscopy (FIB-SEM) in conjunction with high-pressure freezing, freeze-substitution, TEM, and confocal microscopy. We found that P. kofoidii possessed six nuclear tunnels, which were continuous with a reticulating network of membranes that has thus far gone unnoticed. These membranous extensions interconnect the six tunnels while ramifying throughout the nucleus to form a "nuclear net." To our knowledge, the nuclear net is the most elaborate endomembrane structure described within a nucleus. Our findings demonstrate the utility of tomographic approaches for detecting 3D membrane networks and show that nuclear complexity has been underestimated in Polykrikos kofoidii and, potentially, in other dinoflagellates.

SUBMITTER: Gavelis GS

PROVIDER: S-EPMC6351617 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net.

Gavelis Gregory S GS Herranz Maria M Wakeman Kevin C KC Ripken Christina C Mitarai Satoshi S Gile Gillian H GH Keeling Patrick J PJ Leander Brian S BS

Scientific reports 20190129 1

Dinoflagellates are some of the most common eukaryotic cells in the ocean, but have very unusual nuclei. Many exhibit a form of closed mitosis (dinomitosis) wherein the nuclear envelope (NE) invaginates to form one or more trans-nuclear tunnels. Rather than contact spindles directly, the chromatids then bind to membrane-based kinetochores on the NE. To better understand these unique mitotic features, we reconstructed the nuclear architecture of Polykrikos kofoidii in 3D using focused ion beam sc ...[more]

PMID: 30696854

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Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net.

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Dinoflagellate nucleus contains an extensive endomembrane network, the nuclear net.

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