scholarly journals Eukaryotes arose after genetic recombination

2006 ◽  
Vol 14 (1-2) ◽  
pp. 11-14 ◽  
Author(s):  
Milanko Stupar
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Genome Duplication ◽  
Genetic Recombination ◽  
Mitochondrial Gene ◽  
Dna Molecules ◽  
Monophyletic Origin ◽  
Double Stranded Dna ◽  
Rigid Cell Wall

Division of ancestral prokaryotic pragenome into two circular double-stranded DNA molecules by genetic recombination, is a base for future separate evolution of nuclear and mitochondrial gene compartment. This suggests monophyletic origin of both, mitochondrion and nucleus. Presumed organism which genome undergoes genetic recombination has to be searched among an aerobic, oxygen nonproducing, archaeon with no rigid cell wall, but a plasma membrane. Plastid evolves from an aerobic, oxygen producing protoeukaryote, after mitoplastid genome duplication and subsequent functional segregation.

scholarly journals Nucleogenesis and origin of organelles

2008 ◽  
Vol 16 (3-4) ◽  
pp. 88-92
Author(s):  
Milanko Stupar
Keyword(s):  
Replication Fork ◽  
Genome Duplication ◽  
Genetic Recombination ◽  
Mitochondrial Gene ◽  
Strand Break ◽  
Monophyletic Origin ◽  
Double Stranded Dna ◽  
Rigid Cell Wall ◽  
Step Mechanism ◽  
Archaeal Ancestor

Division of the ancestral prokaryotic pragenome into two circular double-stranded DNA molecules by genetic recombination is a base for the future separate evolution of the nuclear and mitochondrial gene compartment. This suggests monophyletic origin of both mitochondrion and nucleus. Presumed organism which genome undergoes genetic recombination has to be searched among an aerobic, oxygen non-producing archaeon with no rigid cell wall, but a plasma membrane. Plastids evolve from an aerobic, oxygen producing proto-eukaryot, after mitoplastide genome duplication and subsequent functional segregation. In this proposal, origin of eukaryots occurs by a three-step mechanism. First, replication fork pauses and collapses generating a breakage in the genome of archaeal ancestor of eukaryots. Second, the double-strand break can be repaired intergenomically by complementary strands invasion. Third, this duplicated genome can be fissioned into two compartments by reciprocal genetic recombination. Scenario is accomplished by aberrant fission of the inner membrane surrounding separately those two compartments.

scholarly journals Genetic recombination and the origin of mitochondrion

2003 ◽  
Vol 11 (1) ◽  
pp. 35-38
Author(s):  
Milanko Stupar
Keyword(s):  
Genetic Recombination ◽  
Prokaryotic Genome ◽  
Dna Molecules ◽  
Double Stranded Dna

Division of ancestral prokaryotic genome into two circular double-stranded DNA molecules is a basis for future separate evolution of nuclear and mitochondrion compartments. Universal double sheet of lipid molecules by invagination, at the level of membrane-hairpin attachment, formed two-layered envelope completely surrounding those two DNAs. Presumed ancestral prokaryote in this case is an Archaebacteria, which would lead to formation of six main groups of organisms: Archaebacteria (Archaea) eubacteria, Protista, Fungi, Plantae and Animalia.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Microanatomy of the Periplasm of Bacillus Licheniformis

1971 ◽  
Vol 29 ◽  
pp. 262-263
Author(s):  
B.K. Ghosh
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Bacillus Licheniformis ◽  
External Environment ◽  
Permeability Barrier ◽  
Periplasmic Space ◽  
Modified Technique ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Periplasm of bacteria is the space outside the permeability barrier of plasma membrane but enclosed by the cell wall. The contents of this special milieu exterior could be regulated by the plasma membrane from the internal, and by the cell wall from the external environment of the cell. Unlike the gram-negative organism, the presence of this space in gram-positive bacteria is still controversial because it cannot be clearly demonstrated. We have shown the importance of some periplasmic bodies in the secretion of penicillinase from Bacillus licheniformis.In negatively stained specimens prepared by a modified technique (Figs. 1 and 2), periplasmic space (PS) contained two kinds of structures: (i) fibrils (F, 100 Å) running perpendicular to the cell wall from the protoplast and (ii) an array of vesicles of various sizes (V), which seem to have evaginated from the protoplast.

Synchrony of Digestion of SV40 DNA by Exonuclease III Determined by EM

1975 ◽  
Vol 33 ◽  
pp. 674-675
Author(s):  
Ray Wu ◽  
G. Ruben ◽  
B. Siegel ◽  
P. Spielman ◽  
E. Jay
Keyword(s):  
Dark Field ◽  
Uranyl Acetate ◽  
Enzyme Digestion ◽  
Dna Molecules ◽  
Exonuclease Iii ◽  
Aluminum Films ◽  
Double Stranded Dna ◽  
Before And After ◽  
Exo Iii ◽  
Sv40 Dna

A method for determining long nucleotide sequences of double-stranded DNA is being developed. It involves (a) the synchronous digestion of the DNA from the 3' ends with EL coli exonuclease III (Exo III) followed by (b) resynthesis with labeled nucleotides and DNA polymerase. A crucial factor in the success of this method is the degree to which the enzyme digestion proceeds synchronously under proper conditions of incubation (step a). Dark field EM is used to obtain accurate measurements on the lengths and distribution of the DNA molecules before and after digestion with Exo III, while gel electrophoresis is used in parallel to obtain a mean length for these molecules. It is the measurements on a large enough sample of individual molecules by EM that provides the information on how synchronously the digestion proceeds. For length measurements, the DNA molecules were picked up on 20-30 Å thick carbon-aluminum films, using the aqueous Kleinschmidt technique and stained with 7.5 x 10-5M uranyl acetate in 90% ethanol for 3 minutes.

Enrichment of vitronectin- and fibronectin-like proteins in NaCI-adapted plant cells and evidence for their involvement in plasma membrane-cell wall adhesion

1993 ◽  
Vol 3 (5) ◽  
pp. 637-646 ◽  
Author(s):  
Jian-Kang Zhu ◽  
Jun Shi ◽  
Utpal Singh ◽  
Sarah E. Wyatt ◽  
Ray A. Bressan ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Plant Cells ◽  
Membrane Cell

scholarly journals Formin-mediated bridging of cell wall, plasma membrane, and cytoskeleton in symbiotic infections of Medicago truncatula

2021 ◽  
Author(s):  
Pengbo Liang ◽  
Clara Schmitz ◽  
Beatrice Lace ◽  
Franck Anicet Ditengou ◽  
Chao Su ◽  
...  
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Medicago Truncatula

scholarly journals With an Ear up Against the Wall: An Update on Mechanoperception in Arabidopsis.

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1587
Author(s):  
Sara Behnami ◽  
Dario Bonetta
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Immune Responses ◽  
Mechanical Stress ◽  
Mechanosensitive Channels ◽  
Compensatory Responses ◽  
Cell Wall Damage ◽  
Mechanical Signals ◽  
Hormone Signalling

Cells interpret mechanical signals and adjust their physiology or development appropriately. In plants, the interface with the outside world is the cell wall, a structure that forms a continuum with the plasma membrane and the cytoskeleton. Mechanical stress from cell wall damage or deformation is interpreted to elicit compensatory responses, hormone signalling, or immune responses. Our understanding of how this is achieved is still evolving; however, we can refer to examples from animals and yeast where more of the details have been worked out. Here, we provide an update on this changing story with a focus on candidate mechanosensitive channels and plasma membrane-localized receptors.

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