scholarly journals Remodeling of neuronal membranes as an early response to deafferentation. A freeze-fracture study.

1977 ◽  
Vol 75 (3) ◽  
pp. 837-850 ◽  
Author(s):  
R L Gulley ◽  
R J Wenthold ◽  
G R Neises
Keyword(s):  
Freeze Fracture ◽  
Early Response ◽  
Postsynaptic Membrane ◽  
Normal Numbers ◽  
Neuronal Membranes ◽  
Anteroventral Cochlear Nucleus ◽  
Different Types ◽  
Fracture Study ◽  
Early Effects ◽  
Number Of Particles

The early effects of deafferentation on the postsynaptic membrane beneath the end bulb of Held in the anteroventral cochlear nucleus (AVCN) were studied with the freeze-fracture technique. Three distinct responses were seen on the external membrane leaflet after cochlear ablation. Within 12 h the number of nonaggregate particles increased 147% by the addition of new particles to the membrane. The increase in number of nonaggregate particles continued until 4 days after cochlear ablation. The other responses occurred later, after degenerative changes were present in the end bulb. Between 1 and 2 days after cochlear ablation, the number of perisynaptic aggregates surrounding the postsynaptic active zone decreased to 10% of normal numbers. By 4 days, all perisynaptic aggregates had disappeared from the membrane. Coated vesicles may be involved in removing these aggregates. Between 1 and 3 days, the number of junctional aggregates decreased, but the size of the aggregates increased, apparently as a result of coalescence of nearby junctional aggregates. The total number of particles in junctional aggregates in the membrane was not altered during the first 6 days after cochlear ablation. The three separate responses suggest the existence of at least three different types of intramembranous particles on the external leaflet of the principal cell membrane, with each type dependent upon different cues for its maintenance in the membrane.

scholarly journals Freeze-fracture study of the Drosophila photoreceptor membrane: mutations affecting membrane particle density.

1982 ◽  
Vol 93 (3) ◽  
pp. 961-967 ◽  
Author(s):  
R H Schinz ◽  
M V Lo ◽  
D C Larrivee ◽  
W L Pak
Keyword(s):  
Vitamin A ◽  
Particle Density ◽  
Freeze Fracture ◽  
Specific Protein ◽  
Wild Type ◽  
Photoreceptor Membrane ◽  
Membrane Particles ◽  
Fracture Study ◽  
Freeze Fracture Electron Microscopy ◽  
Number Of Particles

The photoreceptor membrane of Drosophila melanogaster (wild type, vitamin A-deprived wild type, and the mutants ninaAP228, ninaBP315, and oraJK84) was studied by freeze-fracture electron microscopy. The three mutations caused a decrease in the number of particles on the protoplasmic face of the rhabdomeric membrane. The ninaAP228 mutation affected only the peripheral photoreceptors (R1-6), while the ninaBP315 mutation affected both the peripheral (R1-6) and the central photoreceptors (R7). The oraJK84 mutation, which essentially eliminates R1-6 rhabdomeres, was found to drastically deplete the membrane particles in the vestigial R1-6 rhabdomeres but not in the normal rhabdomeres of R7 photoreceptors, suggesting that the failure of the oraJK84 mutant to form normal R1-6 rhabdomeres may be due to a defect in a major R1-6 photoreceptor-specific protein in the mutant. In all cases in which both the rhabdomeric particle density and rhodopsin content were studied, the mutations or vitamin A deprivation was found to reduce both these quantities, supporting the idea that at least the majority of the rhabdomeric membrane particles are closely associated with rhodopsin. Vitamin A deprivation and the mutations also reduced the number of particles in the plasma membrane as in the rhabdomeric membrane, suggesting that both classes of membrane contain rhodopsin.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

Junctional Pattern in the Squamous Metaplasia of the Female Trigone. A Freeze-Fracture Study

1983 ◽  
Vol 129 (2) ◽  
pp. 280-283 ◽  
Author(s):  
M. Sideri ◽  
G. De Virgiliis ◽  
R. Rainoldi ◽  
A. Ferrari ◽  
G. Remotti
Keyword(s):  
Squamous Metaplasia ◽  
Freeze Fracture ◽  
Fracture Study

Freeze-fracture study of the mechanoreceptive digital corpuscles of mice

1985 ◽  
Vol 14 (6) ◽  
pp. 1037-1052 ◽  
Author(s):  
Chizuka Ide ◽  
Kenichi Kumagai ◽  
Schuichiro Hayashi
Keyword(s):  
Freeze Fracture ◽  
Fracture Study
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