scholarly journals ELECTRON MICROSCOPE OBSERVATIONS ON COMPOUND 48/80-INDUCED DEGRANULATION IN RAT MAST CELLS

1971 ◽  
Vol 51 (2) ◽  
pp. 465-483 ◽  
Author(s):  
Pál Röhlich ◽  
Per Anderson ◽  
Börje Uvnäs
Keyword(s):  
Electron Microscopy ◽  
Mast Cells ◽  
Extracellular Space ◽  
Ultrastructural Changes ◽  
Cell Interior ◽  
Lag Period ◽  
Histamine Liberator ◽  
Granule Matrix ◽  
Rat Mast Cells

In vitro degranulation of rat mast cells was studied at different intervals ranging from 10 to 60 sec after adding the histamine liberator, compound 48/80 (0.4 µg/ml, 17°C). The ultrastructural changes were followed by electron microscopy, and parallel assays were made to determine the histamine released. In addition, the extracellular tracers lanthanum and hemoglobin (demonstrated by its peroxidative activity) were applied to mast cells to follow communication of the extracellular space with the cavities formed during degranulation. After a lag period of 10 sec, degranulation started in the most peripherally located granules. The perigranular membrane fused with the plasma membrane, resulting in a pore bridged by a thin diaphragm. This was followed by rupture of the diaphragm and extrusion of the granule matrix (exocytosis). The process advanced towards the cell interior by fusion and opening of the deeper situated granules to the formerly opened granule cavities. At the end of the process, the cell was filled by a system of complicated cavities containing a number of altered granules. Extracellular tracers have shown that these intracellular cavities were in unbroken communication with the extracellular space from the very beginning of their formation. Both lanthanum and hemoglobin were found to be adsorbed to the limiting membrane of the cavities and bound to altered mast cell granules. In contrast, no tracer substance was present in nondegranulating mast cells. Degranulation of mast cells by compound 48/80 is regarded as a sequential exocytosis, a process similar to that described for some exocrine gland cells. All the "intracellular" cavities, formed by degranulation, were shown to communicate with the extracellular space; consequently, granules lying in these cavities must be considered as biologically extracellular. The present findings support the view that histamine is released from the granule matrix by the extracellular ionic milieu.

scholarly journals Establishment of an in vitro model for analyzing mitochondrial ultrastructure in PRKN-mutated patient iPSC-derived dopaminergic neurons

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Mutsumi Yokota ◽  
Soichiro Kakuta ◽  
Takahiro Shiga ◽  
Kei-ichi Ishikawa ◽  
Hideyuki Okano ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dopaminergic Neurons ◽  
Structural Changes ◽  
In Vitro Model ◽  
Induced Pluripotent Stem Cell ◽  
Substantia Nigra Pars Compacta ◽  
Ultrastructural Changes ◽  
Mitochondrial Morphology ◽  
Vitro Model

AbstractMitochondrial structural changes are associated with the regulation of mitochondrial function, apoptosis, and neurodegenerative diseases. PRKN is known to be involved with various mechanisms of mitochondrial quality control including mitochondrial structural changes. Parkinson’s disease (PD) with PRKN mutations is characterized by the preferential degeneration of dopaminergic neurons in the substantia nigra pars compacta, which has been suggested to result from the accumulation of damaged mitochondria. However, ultrastructural changes of mitochondria specifically in dopaminergic neurons derived from iPSC have rarely been analyzed. The main reason for this would be that the dopaminergic neurons cannot be distinguished directly among a mixture of iPSC-derived differentiated cells under electron microscopy. To selectively label dopaminergic neurons and analyze mitochondrial morphology at the ultrastructural level, we generated control and PRKN-mutated patient tyrosine hydroxylase reporter (TH-GFP) induced pluripotent stem cell (iPSC) lines. Correlative light-electron microscopy analysis and live cell imaging of GFP-expressing dopaminergic neurons indicated that iPSC-derived dopaminergic neurons had smaller and less functional mitochondria than those in non-dopaminergic neurons. Furthermore, the formation of spheroid-shaped mitochondria, which was induced in control dopaminergic neurons by a mitochondrial uncoupler, was inhibited in the PRKN-mutated dopaminergic neurons. These results indicate that our established TH-GFP iPSC lines are useful for characterizing mitochondrial morphology, such as spheroid-shaped mitochondria, in dopaminergic neurons among a mixture of various cell types. Our in vitro model would provide insights into the vulnerability of dopaminergic neurons and the processes leading to the preferential loss of dopaminergic neurons in patients with PRKN mutations.

scholarly journals The ultrastructure changes of Haemonchus contortus exposed to bamboo leaves (Gigantochloa apus) aqueous extract under in vitro condition

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Budi Purwo Widiarso ◽  
WISNU NURCAHYO ◽  
KURNIASIH KURNIASIH ◽  
JOKO PRASTOWO
Keyword(s):  
Electron Microscopy ◽  
Aqueous Extract ◽  
Haemonchus Contortus ◽  
Leaf Extract ◽  
Structural Changes ◽  
Ultrastructural Changes ◽  
Bamboo Leaves ◽  
Transmission Electron ◽  
External Part

Abstract. Widiarso, Nurcahyo W, Kurniasih, Prastowo J. 2021. The ultrastructure changes of Haemonchus contortus exposed to bamboo leaves (Gigantochloa apus) aqueous extract under in vitro condition. Biodiversitas 22: 1-5. The ultrastructural changes induced in adult Haemonchus contortus in vitro using the aqueous extract of bamboo leaves were assessed using scanning electron microscopy (SEM). The H. contortus adult females were obtained from three groups and treatment was repeated thrice. The first group (T0) was not treated with bamboo leaves; 100% of the worms lived. The second group (T1), treated with 0.1% bamboo leaf-extract, had 50% mortality 4 h after examination. The third group (T2), treated with 1% bamboo leaf-extract, had 100% mortality 4 h after examination. Five worms used per treatment were submerged in ethanol and incubated for 24 hours. The ultrastructural changes observed by SEM revealed structural alteration of the worm surface after in vitro contact with the bamboo leaf aqueous extract and compared to the control worms. The main changes concerned the anterior end or cephalic region, cuticle surface, and vulva flap area. The structural modification of the external part of the female reproductive system was found only in vitro. The structural changes found in the worms exposed to the bamboo leaves might affect their motility and nutrition with possible consequences on their reproduction. Transmission electron microscopy may help to understand the external changes observed in H. contortus.

In vitro hyposensitization of rat mast cells by antigen

1974 ◽  
Vol 4 (3) ◽  
pp. 204-204 ◽  
Author(s):  
P. Stahl Skov ◽  
S. Norn
Keyword(s):  
Mast Cells ◽  
Rat Mast Cells

scholarly journals Further studies on the structural requirements for polypeptide-mediated histamine release from rat mast cells

1979 ◽  
Vol 181 (3) ◽  
pp. 623-632 ◽  
Author(s):  
B Jasani ◽  
G Kreil ◽  
B F Mackler ◽  
D R Stanworth
Keyword(s):  
Amino Acids ◽  
Mast Cells ◽  
Histamine Release ◽  
Immunoglobulin E ◽  
Polymyxin B ◽  
Carboxyl Group ◽  
Peritoneal Mast Cells ◽  
Normal Rat ◽  
Rat Mast Cells

Structure-activity studies have been performed on a series of naturally occurring and ‘tailor-made’ polypeptides, by measurement of ability to induce selective histamine release from normal rat peritoneal mast cells in vitro. Compounds investigated include corticotropin and melittin derivatives, mast-cell-degranulating peptide from bee venom, polymyxin B, bradykinin and various synthetic poly(amino acids) and short-chain peptides. It was confirmed that a cluster of four basic residues (lysine or arginine) was optimal for histamine release by corticotropin and melittin polypeptides, provided that the C-terminal carboxyl group was substituted (by, for instance, amidation). In contrast, the presence of a free C-terminal carboxyl group or nearby dicarboxylic acid residues led to a considerable diminution in histamine-releasing activity. Likewise, polypeptides comprised essentially of acidic amino acids were inactive. On the basis of these observations it has been possible to predict that synthetic peptides comprising a particular sequence within the Fc region of human immunoglobulin E, the immunoglobulin class particularly involved in mediation of allergic reactions of the immediate type, would possess potent histamine-releasing activity when similarly made to react with normal rat mast cells. The further study of such a structure should throw new light on the molecular basis of allergen-antibody triggering of mast cells.

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