Microfibrillar structures in the nucleus and cytoplasm of amoeba proteus (1)

Leeson, Thomas S.; Bhatnagar, Rakesh

doi:10.1002/jez.1401920216

Cited by 9 publications

(4 citation statements)

References 18 publications

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“…Since this 'zone of exclusion' appeared to contain cytoskeletal elements, including microfilaments and microtubules, it was putatively identified as the perinuclear actin shell [Henderson and Locke, 1992]. In Amoeba, microfibrils with a size similar to filamentous-actin, associate with both the cytoplasmic and nucleoplasmic faces of the nuclear envelope [Leeson and Bhatnagar, 1975]. The only example of perinuclear actin shells whose location is known is in the fungus Neozygites, where the diameter of actin shells is consistently larger than the diameter of the associated nucleus, and must be cytoplasmic [Butt and Heath, 1988].…”

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Peripheral nuclear matrix actin forms perinuclear shells

Clubb

Locke

1998

J. Cell. Biochem.

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Perinuclear actin shells have been reported in a variety of organisms. The shells have been identified by staining perinuclear material with fluorescently-labelled phalloidin, but have not been localized to a specific subcellular compartment at the ultrastructural level. We show here that the shells of 3T3 cells lie in the peripheral nuclear matrix. Nuclear shells and matrix actin in other parts of the nucleus are not usually detected by immunohistochemical staining because they are inaccessible to antibodies or to phalloidin. Immunohistochemical detection of nuclear actin is only possible during its deposition at the end of mitosis, or in interphase nuclei that have been extracted with detergent, digested with nucleases and washed with high salt buffers.

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“…Electron microscopy of Amoeba nuclei showed parallel bands of thin filaments next to the nuclear lamina [Leeson and Bhatnagar, 1975]. Nuclear-associated fractions prepared from Calpodes silk gland cells contain two distinct fibrous networks [Henderson and Locke, 1992].…”

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confidence: 98%

Peripheral nuclear matrix actin forms perinuclear shells

Clubb

Locke

1998

J. Cell. Biochem.

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“…Since some of the earliest ultrastructural studies of diverse eukaryotes, and particularly amoebae, it has been clear that the basic organization of the NE was probably highly conserved, with both NE membranes closely opposed in nearly all organisms. The presence of nuclear pores was also obvious from these studies, as well as the presence of diffuse material embedded within the pores, the NPC, together with a lamina . Ultrastructure alone, however, is insufficient to determine if there is structural or mechanistic conservation between NPCs from different taxa, but sequencing of diverse eukaryotic genomes in the last decade or so, together with pioneering proteomic studies in metazoan and fungal model systems provided a parts list for the NPC in opisthokont taxa ( Saccharomyces cerevisiae and Rattus rattus ) and facilitated comparative genomics and proteomics to extend this understanding into additional supergroups (Figure ).…”

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Enriching the Pore: Splendid Complexity from Humble Origins

Field

Kořený

Rout

2014

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The nucleus is the defining intracellular organelle of eukaryotic cells and represents a major structural innovation that differentiates the eukaryotic and prokaryotic cellular form. The presence of a nuclear envelope (NE) encapsulating the nucleus necessitates a mechanism for interchange between the contents of the nuclear interior and the cytoplasm, which is mediated via the nuclear pore complex (NPC), a large protein assembly residing in nuclear pores in the NE. Recent advances have begun to map the structure and functions of the NPC in multiple organisms, and to allow reconstruction of some of the evolutionary events that underpin the modern NPC form, highlighting common and differential NPC features across the eukaryotes. Here we discuss some of these advances and the questions being pursued, consider how the evolution of the NPC has been constrained, and finally propose a model for how the nuclear pore complex evolved.

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“…These nuclei do, however, seem to share a number of certain features in the electron microscope: every nucleus is bounded by a double-membraned nuclear envelope (NE), perforated by nuclear pore complexes (NPCs) and often underlayered on the nuclear periphery by a dense lamina 1 - 4 . Electron dense bodies such as the nucleolus are commonly found in the nuclear interior; and even the earliest light microscopic studies recognized that chromatin, the nucleus’ packaged DNA, seemed to come in less and more densely packaged forms, termed euchromatin and heterochromatin respectively 5 .…”

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confidence: 99%

Telomeres, tethers and trypanosomes

Field

Horn

Alsford

et al. 2012

Nucleus

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Temporal and spatial organization of the nucleus is critical for the control of transcription, mRNA processing and the assembly of ribosomes. This includes the occupancy of specific territories by mammalian chromosomes, the presence of subnuclear compartments such as the nucleolus and Cajal bodies and the division of chromatin between active and inactive states. These latter are commonly associated with the location of DNA within euchromatin and heterochromatin respectively; critically these distinctions arise through modifications to chromatin-associated proteins, including histones, as well as the preferential localization of heterochromatin at the nuclear periphery. Most research on nuclear organization has focused on metazoa and fungi; however, recent technical advances have made more divergent eukaryotes accessible to study, with some surprising results. For example, the organization of heterochromatin is mediated in metazoan nuclei in large part by lamins, the prototypical intermediate filament proteins. Despite the presence of heterochromatin, detected both biochemically and by EM in most eukaryotic organisms, until this year lamins were thought to be restricted to metazoan taxa, and the proteins comprising the lamina in other lineages were unknown. Recent work indicates the presence of lamin orthologs in amoeba, while trypanosomatids possess a large coiled-coil protein, NUP-1, that performs functions analogous to lamins. These data indicate that the presence of a nuclear lamina is substantially more widespread than previously thought, with major implications for the evolution of eukaryotic gene expression mechanisms. We discuss these and other recent findings on the organization of nuclei in diverse organisms, and the implications of these findings for the evolutionary origin of eukaryotes.

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Microfibrillar structures in the nucleus and cytoplasm of amoeba proteus (1)

Cited by 9 publications

References 18 publications

Peripheral nuclear matrix actin forms perinuclear shells

Peripheral nuclear matrix actin forms perinuclear shells

Enriching the Pore: Splendid Complexity from Humble Origins

Telomeres, tethers and trypanosomes

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