The Protistan Origins of Animal Cell Differentiation

Animal Cell Differentiation Patterns Suppress Somatic Evolution

PLoS Computational Biology ◽

10.1371/journal.pcbi.0030250.eor ◽

2005 ◽

Vol preprint (2007) ◽

pp. e250

Author(s):

John William Pepper ◽

Kathleen Sprouffske ◽

Carlo C. Maley

Keyword(s):

Cell Differentiation ◽

Animal Cell ◽

Somatic Evolution

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The architecture of cell differentiation in choanoflagellates and sponge choanocytes

10.1101/452185 ◽

2018 ◽

Cited By ~ 1

Author(s):

Davis Laundon ◽

Ben Larson ◽

Kent McDonald ◽

Nicole King ◽

Pawel Burkhardt

Keyword(s):

Cell Differentiation ◽

Cell Biology ◽

Animal Cell ◽

Cell Activity ◽

Cell Types ◽

Cell Contact ◽

Last Common Ancestor ◽

Animal Kingdom ◽

Variable Nature ◽

Salpingoeca Rosetta

SUMMARYCollar cells are ancient animal cell types which are conserved across the animal kingdom [1] and their closest relatives, the choanoflagellates [2]. However, little is known about their ancestry, their subcellular architecture, or how they differentiate. The choanoflagellate Salpingoeca rosetta [3] expresses genes necessary for animal multicellularity and development [4] and can alternate between unicellular and multicellular states [3,5], making it a powerful model to investigate the origin of animal multicellularity and mechanisms underlying cell differentiation [6,7]. To compare the subcellular architecture of solitary collar cells in S. rosetta with that of multicellular “rosettes” and collar cells in sponges, we reconstructed entire cells in 3D through transmission electron microscopy on serial ultrathin sections. Structural analysis of our 3D reconstructions revealed important differences between single and colonial choanoflagellate cells, with colonial cells exhibiting a more amoeboid morphology consistent with relatively high levels of macropinocytotic activity. Comparison of multiple reconstructed rosette colonies highlighted the variable nature of cell sizes, cell-cell contact networks and colony arrangement. Importantly, we uncovered the presence of elongated cells in some rosette colonies that likely represent a distinct and differentiated cell type. Intercellular bridges within choanoflagellate colonies displayed a variety of morphologies and connected some, but not all, neighbouring cells. Reconstruction of sponge choanocytes revealed both ultrastructural commonalities and differences in comparison to choanoflagellates. Choanocytes and colonial choanoflagellates are typified by high amoeboid cell activity. In both, the number of microvilli and volumetric proportion of the Golgi apparatus are comparable, whereas choanocytes devote less of their cell volume to the nucleus and mitochondria than choanoflagellates and more of their volume to food vacuoles. Together, our comparative reconstructions uncover the architecture of cell differentiation in choanoflagellates and sponge choanocytes and constitute an important step in reconstructing the cell biology of the last common ancestor of the animal kingdom.

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The reversible control of animal cell differentiation by the thymidine analog, 5-bromodeoxyuridine

Experimental Cell Research ◽

10.1016/0014-4827(70)90606-3 ◽

1970 ◽

Vol 59 (2) ◽

pp. 319-328 ◽

Cited By ~ 83

Author(s):

Annette W. Coleman ◽

J.R. Coleman ◽

D. Kankel ◽

I. Werner

Keyword(s):

Cell Differentiation ◽

Animal Cell ◽

Thymidine Analog

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Electron Microscopic Analysis of Asymmetry within the Cell Nucleus of DNA Helix Openings During Human Cell Activation and Cell Differentiation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600002403 ◽

1980 ◽

Vol 38 ◽

pp. 544-545

Author(s):

J. H. Frenster

Keyword(s):

Cell Differentiation ◽

Steroid Hormones ◽

Rna Synthesis ◽

Cell Activation ◽

Animal Cell ◽

Microscopic Analysis ◽

Oncogenic Viruses ◽

Dna Molecules ◽

Electron Microscopic ◽

Organ Regeneration

Most of the DNA molecules within an animal cell are repressed for RNA synthesis at any one time, and those DNA molecules that are active are characteristic of the particular tissue or organ within which the cell has differentiated (1). This phenomena of differential gene transcription is thought to be the epigenetic basis for such diverse cell activities as cell differentiation organ regeneration, neoplastic transformation, immune activation, and the response to steroid hormones (2). Carcinogenic chemicals, oncogenic viruses, embryogenic RNA, immune RNA, and steroid hormones all prefer to bind to single-stranded regions within DNA molecules of the host cell (3). DNA molecules which are active in RNA synthesis display short loops of such single-stranded DNA (4), which are a necessary prerequisite for the gene de-repression characteristic of animal neoplasms (5).

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Animal Cell Differentiation Patterns Suppress Somatic Evolution

PLoS Computational Biology ◽

10.1371/journal.pcbi.0030250 ◽

2007 ◽

Vol 3 (12) ◽

pp. e250 ◽

Cited By ~ 50

Author(s):

John W Pepper ◽

Kathleen Sprouffske ◽

Carlo C Maley

Keyword(s):

Cell Differentiation ◽

Animal Cell ◽

Somatic Evolution

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Electron microscope study of the secretory activity of epithelial cells in embryonic thymus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015945x ◽

1990 ◽

Vol 48 (3) ◽

pp. 382-383

Author(s):

H. Alasam

Keyword(s):

Cell Differentiation ◽

T Cell ◽

Epithelial Cells ◽

Electron Density ◽

Secretory Activity ◽

T Cell Differentiation ◽

High Electron ◽

Transmission Electron ◽

Medullary Epithelial Cells ◽

Thymic Factor

The possibility that intrathymic T-cell differentiation involves stem cell-lymphoid interactions in embryos led us to study the ultrastructure of epithelial cell in normal embryonic thymus. Studies in adult thymus showed that it produces several peptides that induce T-cell differentiation. Several of them have been chemically characterized, such as thymosin α 1, thymopoietin, thymic humoral factor or the serum thymic factor. It was suggested that most of these factors are secreted by populations of A and B-epithelial cells.Embryonic materials were obtained from inbred matings of Swiss Albino mice. Thymuses were disected from embryos 17 days old and prepared for transmission electron microscopy. Our studies showed that embryonic thymus at this stage contains undifferentiated and differentiated epithelial cells, large lymphoblasts, medium and few small lymphocytes (Fig. 5). No differences were found between cortical and medullary epithelial cells, in contrast to the findings of Van Vliet et al,. Epithelial cells were mostly of the A-type with low electron density in both cytoplasm and nucleus. However few B-type with high electron density were also found (Fig. 7).

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