scholarly journals Deep phylogeny, ancestral groups and the four ages of life

2010 ◽  
Vol 365 (1537) ◽  
pp. 111-132 ◽  
Author(s):  
Thomas Cavalier-Smith
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Gene Transfer ◽  
Outer Membrane ◽  
Rough Endoplasmic Reticulum ◽  
Cell Structure ◽  
Membrane Topology ◽  
Endoplasmic Reticulum Membrane ◽  
Body Plan Evolution ◽  
History Of

Organismal phylogeny depends on cell division, stasis, mutational divergence, cell mergers (by sex or symbiogenesis), lateral gene transfer and death. The tree of life is a useful metaphor for organismal genealogical history provided we recognize that branches sometimes fuse. Hennigian cladistics emphasizes only lineage splitting, ignoring most other major phylogenetic processes. Though methodologically useful it has been conceptually confusing and harmed taxonomy, especially in mistakenly opposing ancestral (paraphyletic) taxa. The history of life involved about 10 really major innovations in cell structure. In membrane topology, there were five successive kinds of cell: (i) negibacteria, with two bounding membranes, (ii) unibacteria, with one bounding and no internal membranes, (iii) eukaryotes with endomembranes and mitochondria, (iv) plants with chloroplasts and (v) finally, chromists with plastids inside the rough endoplasmic reticulum. Membrane chemistry divides negibacteria into the more advanced Glycobacteria (e.g. Cyanobacteria and Proteobacteria) with outer membrane lipolysaccharide and primitive Eobacteria without lipopolysaccharide (deserving intenser study). It also divides unibacteria into posibacteria, ancestors of eukaryotes, and archaebacteria—the sisters (not ancestors) of eukaryotes and the youngest bacterial phylum. Anaerobic eobacteria, oxygenic cyanobacteria, desiccation-resistant posibacteria and finally neomura (eukaryotes plus archaebacteria) successively transformed Earth. Accidents and organizational constraints are as important as adaptiveness in body plan evolution.

The Fine Structure of Primordial Germ Cells of the Rat

1973 ◽  
Vol 31 ◽  
pp. 634-635
Author(s):  
E. M. Eddy
Keyword(s):  
Endoplasmic Reticulum ◽  
Life History ◽  
Fine Structure ◽  
Rough Endoplasmic Reticulum ◽  
Germ Cells ◽  
Fibrous Material ◽  
Primordial Germ Cells ◽  
The Other ◽  
Large Size ◽  
History Of

Primordial germ cells are readily recognizable in embryos of the rat due to their large size, generally rounded shape and prominent nuclei with uniformly dispersed heterochromatin. They often have blunted pseudopodal processes at one end and small ruffles or trailing processes at the other, characteristics expected from their known ameboid activity- and migratory abilities. Also, the cytoplasm is rich in polyribosomes and contains a modest amount of rough endoplasmic reticulum and the mitochondria are frequently larger and less dense than those of adjacent somatic cells.In addition to these general characteristics, there are features unique to germ cells which allow them to be identified with certainty. These are: 1) small vesicles containing an irregular, dense core and 2) discrete accumulations of fibrous material known as nuage. Both of these features are present in other species and at other times in the life history of germ cells. The dense-cored vesicles have been noted in fetal and early postnatal mouse oogonia and oocytes, and in hamster and rabbit oocytes.

scholarly journals The eta isoform of protein kinase C is localized on rough endoplasmic reticulum.

1994 ◽  
Vol 14 (6) ◽  
pp. 3782-3790 ◽  
Author(s):  
K Chida ◽  
H Sagara ◽  
Y Suzuki ◽  
A Murakami ◽  
S Osada ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Rough Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Mouse Skin ◽  
Endoplasmic Reticulum Membrane ◽  
Present Observation ◽  
Outer Nuclear Membrane ◽  
Kinase C

The eta isoform of protein kinase C, isolated from a cDNA library of mouse skin, has unique tissue and cellular distributions. It is predominantly expressed in epithelia of the skin, digestive tract, and respiratory tract in close association with epithelial differentiation. We report here that this isoform is localized on the rough endoplasmic reticulum in transiently expressing COS1 cells and constitutively expressing keratinocytes. By the use of polyclonal antibodies raised against peptides of the diverse D1 and D2/D3 regions, we found that immunofluorescent signals were strongest in the cytoplasm around the nucleus and became weaker toward the peripheral cytoplasm. Under immunoelectron microscopic examination, electron-dense signals were located on the rough endoplasmic reticulum and on the outer nuclear membrane which is continuous with the endoplasmic reticulum membrane. However, no signals were detected in the nucleus, inner nuclear membrane, smooth endoplasmic reticulum, Golgi apparatus, mitochondria, or plasma membrane. Treatment of the cells in situ with detergents suggested association of the isoform of protein kinase C with intracellular structures. By immunoblotting, a distinct single band with an M(r) of 80,000 was detected in whole-cell lysate and in rough microsomal and crude nuclear fractions, all of which contain outer nuclear membrane and/or rough endoplasmic reticulum. We further demonstrated the absence of a nuclear localization signal in the pseudosubstrate sequence. The present observation is not consistent with the report of Greif et al. (H. Greif, J. Ben-Chaim, T. Shimon, E. Bechor, H. Eldar, and E. Livneh, Mol. Cell. Biol. 12:1304-1311, 1992).

Glycoproteins of the rough endoplasmic reticulum membrane

1989 ◽  
Vol 17 (1) ◽  
pp. 107-108
Author(s):  
CLIVE MEREDITH ◽  
MUSTAK KADERBHAI ◽  
BRIAN AUSTEN
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Membrane

scholarly journals Transfer of Septin Rings to Cytokinetic Remnants Directs Age-Sensitive ER stress Surveillance Cell Cycle Re-entry

2019 ◽  
Author(s):  
Jesse T. Chao ◽  
Francisco Piña ◽  
Masayuki Onishi ◽  
Yifat Cohen ◽  
Maya Schuldiner ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Er Stress ◽  
Growth Failure ◽  
Negative Polarity ◽  
Stress Recovery ◽  
Septin Ring ◽  
History Of ◽  
Er Homeostasis

SUMMARYDuring cell division, cells must actively pass on organelles. Previously, we discovered the endoplasmic reticulum (ER) stress surveillance (ERSU) pathway that ensures the inheritance of functional ER. Activation of the ERSU causes the septin ring to mislocalize, which blocks ER inheritance and cytokinesis. Here, we found that the septin ring mislocalizes to previously utilized cell division sites called cytokinetic remnants (CRMs). The transfer of the septin ring to CRMs requires Nba1, a negative polarity component that normally prevents septin ring formation at CRMs. Furthermore, septin ring movement to CRMs relies on the ERSU component Slt2, which is recruited by binding Bem1. During ER stress, Bem1 also binds the GTP exchange factor Cdc24, without activating Cdc42, a GTPase that normally establishes polarized growth. Failure to translocate septin rings to CRMs delays the cell’s ability to re-enter cell division when ER homeostasis is re-established. Thus, ER stress considers the history of previous cell cycle for future cell cycle re-entry upon ER stress recovery.

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