scholarly journals Endosome Independent - Vesicular Transport and Targeting of the Leishmania RNA Import Complex to Mammalian Mitochondria in Vivo and in Vitro

2015 ◽  
Vol 29 ◽  
pp. 574.4
Author(s):  
JOYITA MUKHERJEE ◽  
Biraj MAHATO ◽  
SANDIP KOLEY ◽  
SAMIT ADHYA
Keyword(s):  
Vesicular Transport ◽  
Mammalian Mitochondria ◽  
Rna Import

scholarly journals The identification of mecciRNAs and their roles in mitochondrial entry of proteins

2019 ◽  
Author(s):  
Xu Liu ◽  
Xiaolin Wang ◽  
Jingxin Li ◽  
Shanshan Hu ◽  
Yuqi Deng ◽  
...  
Keyword(s):  
Molecular Chaperones ◽  
Mitochondrial Protein ◽  
Nuclear Genome ◽  
Circular Rnas ◽  
Physiological Conditions ◽  
Mammalian Mitochondria ◽  
Protein Entry ◽  
Regulate Protein

AbstractMammalian mitochondria have small genomes encoding very limited numbers of proteins. Over one thousand proteins and noncoding RNAs encoded by nuclear genome have to be imported from the cytosol into the mitochondria. Here we report the identification of hundreds of circular RNAs (mecciRNAs) encoded by mitochondrial genome. We provide both in vitro and in vivo evidence to show that mecciRNAs facilitate mitochondrial entry of nuclear-encoded proteins by serving as molecular chaperones in the folding of imported proteins. Known components of mitochondrial protein and RNA importation such as TOM40 and PNPASE interact with mecciRNAs and regulate protein entry. Expression of mecciRNAs is regulated, and these transcripts are critical for mitochondria in adapting to physiological conditions and diseases such as stresses and cancers by modulating mitochondrial protein importation. mecciRNAs and their associated physiological roles add categories and functions to eukaryotic circular RNAs, and shed novel lights on communication between mitochondria and nucleus.

Effect of radiosensitizing agents on electron transport systems

1978 ◽  
Vol 56 (6) ◽  
pp. 457-461 ◽  
Author(s):  
P. J. Ainsworth ◽  
M. Channon ◽  
R. Sridhar ◽  
B. Gushulak ◽  
E. Reno Tustanoff
Keyword(s):  
Electron Transport ◽  
Redox Potential ◽  
Cell System ◽  
Transport Systems ◽  
Pyridine Nucleotides ◽  
Redox Potentials ◽  
Radiosensitizing Agents ◽  
Mammalian Mitochondria

Experiments have been carried out to study the interaction between chemical radiosensitizing agents and model electron transport systems. Using an NAD(P)H:O2 oxidoreductase enzyme as such a model, it was demonstrated that radiosensitizers can act as intermediates in the transfer of electrons from NADH to O2, even in the presence of classical inhibitors of electron transport, with an efficiency related to both their redox potentials and their radiosensitizing abilities. This work which was further confirmed in mammalian mitochondria and microsomes as well as in a cultured cell system indicated that these sensitizers can accept electrons from a variety of organelle systems. This action was shown to be related to the concentration of reduced pyridine nucleotides present both in vivo and in vitro. Of the electron-affinic agents tested, those whose redox potential was more negative than −0.39 V may possibly serve as better radiotherapeutic mediators.

scholarly journals Mitofusins and OPA1 Mediate Sequential Steps in Mitochondrial Membrane Fusion

2009 ◽  
Vol 20 (15) ◽  
pp. 3525-3532 ◽  
Author(s):  
Zhiyin Song ◽  
Mariam Ghochani ◽  
J. Michael McCaffery ◽  
Terrence G. Frey ◽  
David C. Chan
Keyword(s):  
Membrane Fusion ◽  
Outer Membrane ◽  
Null Mouse ◽  
Tight Coupling ◽  
Inner Membrane ◽  
Mammalian Mitochondria ◽  
Mouse Cells ◽  
Large Gtpases

Mitochondrial fusion requires the coordinated fusion of the outer and inner membranes. Three large GTPases—OPA1 and the mitofusins Mfn1 and Mfn2—are essential for the fusion of mammalian mitochondria. OPA1 is mutated in dominant optic atrophy, a neurodegenerative disease of the optic nerve. In yeast, the OPA1 ortholog Mgm1 is required for inner membrane fusion in vitro; nevertheless, yeast lacking Mgm1 show neither outer nor inner membrane fusion in vivo, because of the tight coupling between these two processes. We find that outer membrane fusion can be readily visualized in OPA1-null mouse cells in vivo, but these events do not progress to inner membrane fusion. Similar defects are found in cells lacking prohibitins, which are required for proper OPA1 processing. In contrast, double Mfn-null cells show neither outer nor inner membrane fusion. Mitochondria in OPA1-null cells often contain multiple matrix compartments bounded together by a single outer membrane, consistent with uncoupling of outer versus inner membrane fusion. In addition, unlike mitofusins and yeast Mgm1, OPA1 is not required on adjacent mitochondria to mediate membrane fusion. These results indicate that mammalian mitofusins and OPA1 mediate distinct sequential fusion steps that are readily uncoupled, in contrast to the situation in yeast.

scholarly journals In vivo and in vitro evidence for slipped mispairing in mammalian mitochondria.

1993 ◽  
Vol 90 (16) ◽  
pp. 7671-7675 ◽  
Author(s):  
C. S. Madsen ◽  
S. C. Ghivizzani ◽  
W. W. Hauswirth
Keyword(s):  
Mammalian Mitochondria

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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