Actin-dependent light-induced translocation of mitochondria and ER cisternae in the photoreceptor cells of the locust Schistocerca gregaria

1995 ◽  
Vol 108 (6) ◽  
pp. 2273-2283 ◽  
Author(s):  
K. Sturmer ◽  
O. Baumann ◽  
B. Walz
Keyword(s):  
Actin Filaments ◽  
Cytochalasin B ◽  
Schistocerca Gregaria ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Electron Microscopic ◽  
Filament Bundles

Light-dependent changes in the positioning of organelles in photoreceptor cells of arthropods are a well-known phenomenon. In this study, we examine the role of the cytoskeleton in these light-dependent antagonistic movements. In dark-adapted photoreceptor cells of the locust Schistocerca gregaria, prominent sacs of smooth endoplasmic reticulum (ER) oppose the bases of the photoreceptive microvilli. Light stimulation causes a translocation of the ER elements towards the main cell body, and an aggregation of mitochondria adjacent to the microvilli. Immunofluorescence studies and electron-microscopic examination of chemically fixed or high-pressure-frozen, freeze-substituted specimens demonstrate a lack of microtubules in the submicrovillar region. However, numerous filament bundles are aligned in close association with mitochondria and ER elements, along the track of their movement. Fluorescent phallotoxins and monoclonal anti-actin antibodies label filament bundles in the submicrovillar region, indicating that they are composed of F-actin. Finally, depolymerization of the submicrovillar actin filaments by incubation with cytochalasin B results in a blockade of the movement of mitochondria and ER cisternae towards the rhabdom. These results suggest that the light-dependent translocation of both ER cisternae and mitochondria occurs along actin filaments.

A quantitative morphological study of the pineal organ in the goldfish, Carassius auratus

1981 ◽  
Vol 59 (7) ◽  
pp. 1312-1325 ◽  
Author(s):  
John A. McNulty
Keyword(s):  
Endoplasmic Reticulum ◽  
Pineal Organ ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Photoreceptor Cells ◽  
Nerve Fibers ◽  
Substantial Part ◽  
Electron Microscopic ◽  
Goldfish Carassius Auratus ◽  
Supportive Cells

Stereological techniques applied to a light and electron microscopic study of the pineal organ of the goldfish indicated that photoreceptor and supportive cells were comparable in their number and cell volume and that approximately 500 nerve cells were present in the pineal end vesicle. There were approximately 310 nerve fibers descending the distal part of the pineal tract. Quantitative analysis of organelles in photoreceptor cells revealed that the endoplasmic reticulum and Golgi bodies, in the vicinity of which were situated both clear and dense-cored vesicles, formed a substantial part of the cytoplasmic volume. Other new observations reported for this species include a close association between mitochondria and parts of the smooth endoplasmic reticulum, a characteristic feature of photoreceptor cells, and the presence of subsurface cisternae formed from profiles of endoplasmic reticulum. Moreover, specialized contacts were found between both photoreceptor and supportive cells. Some of these ultrastructural features are similar to those reported in the secretory pinealocytes of mammals. These findings suggest that (1) the pineal organ in this species has a high degree of photosensitivity as evidenced by the large number of photoreceptor cells related to each nerve cell, and (2) photoreceptor cells are metabolically active possibly having functions other than photoreception.

Effect of colcemid on the locomotory behaviour of fibroblasts

Development ◽  
1970 ◽  
Vol 24 (3) ◽  
pp. 625-640
Author(s):  
Ju. M. Vasiliev ◽  
I. M. Gelfand ◽  
L. V. Domnina ◽  
O. Y. Ivanova ◽  
S. G. Komm ◽  
...  
Keyword(s):  
Cell Surface ◽  
Electron Microscopic Examination ◽  
Mouse Fibroblast ◽  
Active State ◽  
Structural Basis ◽  
Fish Scale ◽  
Electron Microscopic ◽  
Locomotory Behaviour ◽  
Embryonic Fibroblast

Effects of metaphase inhibitors (colcemid, colchicine, vinblastine) on mouse and human embryonic, fibroblast-like cells growing on glass and on an oriented substrate (fish scale) were studied. All three inhibitors caused similar changes in the form of interphase cells and inhibited their directional locomotion. The effects of two inhibitors (colcemid and vinblastine) were found to be completely reversible. Microcinematographic studies have shown that the most conspicuous change of locomotory behaviour induced by colcemid was the disappearance of non-active stable parts of the cell edge; in normal cells only the leading part of the edge was actively moving, while in colcemid-treated cells all parts of the edge eventually became active. Activation of the whole edge made these cells unable to perform directional translocation. It is suggested that colcemid and other metaphase inhibitors prevent stabilization of the non-active state of the cell surface. The possible role of this suggested colcemid-sensitive stabilization mechanism in the normal locomotory behaviour of fibroblasts is discussed. Electron-microscopic examination has shown that microtubules disappeared from the cytoplasm of colcemid-treated, mouse, fibroblast-like cells. The formation of microtubules as the possible structural basis of the stabilization of the non-active state of the cell surface is discussed.

Microtubules and associated microfilaments in the tentacles of the suctorian Heliophrya erhardi Matthes

1976 ◽  
Vol 20 (3) ◽  
pp. 589-617
Author(s):  
M. Hauser ◽  
H. Van Eys
Keyword(s):  
Plasma Membrane ◽  
Resting State ◽  
Close Association ◽  
Ultrastructural Level ◽  
Peritrophic Membrane ◽  
Electron Microscopic ◽  
Helical Wave ◽  
Length Changes ◽  
Microscopic Findings

At the ultrastructural level length changes accompanying linear movements of resting (non-feeding) tentacles of the suctorian Heliophrya involve not only altered microtubule numbers, but also marked changes in the specific microtubule pattern of cross-sectioned tentacles. These changes in number and pattern indicate a sliding between axonemal microtubules. The visualization of microfilaments in the cytoplasm at the tentacle base and in the knob region could shed new light on the problem of whether microtubular sliding is an active or passive process. At the tentacle base, microfilaments are either arranged in a ring-shaped configuration around the axoneme, or they run parallel to the axonemal microtubules, whereas at the tentacle tip during the resting state, microfilaments are closely associated with the plasma membrane of the knob. They form a filamentous reticular layer, which is continuous at the anchorage site of axonemal microtubules with the dense epiplasmic layer of the tentacle shaft. Obiously, this filamentous layer is engaged in positioning the haptocysts at the plasma membrane and in holding the membrane itself under tension. The putative contractile nature of microfilaments and the epiplasmic layer is argued from ATP-sensitive glycerol models of tentacles and from the results of halothane treatment of native tentacles. Halothane treatment of resting tentacles also gave indications of the presence of differentially stable intermicrotubule-bridges. The role of micro-filaments and halothane-resistant dynein-like inter-row bridges in tentacle movement is discussed. As soon as the plasma membrane of the knob is ‘sealed’ with the prey pellicle during feeding, the microtubules of the sleeve region slide into the knob where they bend back and outwards. The microtubules now appear decorated and sometimes cross-connected by microfilaments which adhere closely to the plasma membrane- now acting as a peritrophic membrane-lining the prey cytoplasm against the microtubules of the inner tube. These microfilaments which show a close association with the microtubules of the active knob area, are thought to be engaged in microtubular bending and stretching during feeding. They may also be involved in the transport of the peritrophic membrane in distal tentacle regions. Microinematographically recorded oscillations in tentacle diameter in these regions are in agreement with the electron-microscopic findings of various states of collapsed tentacle axonemes. These observations, as well as the occurrence of helically twisted tentacles during feeding, suggest microfilament mediated sequential back and forth movements of sleeve microtubules in the knob region which generate a proximally migrating helical wave.

The effects of intravitreally injected bevacizumab on the retina and retina pigment epithelium: experimental in-vivo electron microscopic study in intact versus vitrectomized eyes

Open Medicine ◽  
2010 ◽  
Vol 5 (6) ◽  
pp. 745-751 ◽  
Author(s):  
Nilufer Kocak ◽  
Candan Ozogul ◽  
Suleyman Kaynak ◽  
Ulker Sonmez ◽  
Mehmet Zengin ◽  
...  
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Intravitreal Bevacizumab ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Control Group ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Electron Microscopes

AbstractTo analyze the retinal toxicity of bevacizumab at various doses both in vitrectomized and non-vitrectomized rabbit models. Twenty- eight rabbits were included in the study. Twenty- four rabbits were assigned to six groups, with 4 of the rabbits in the control group. The animals in Groups 1, 2 and 3 received bevacizumab at a dose of 0.3 mg, 0.5 mg and 1.5 mg /eye, respectively. The rabbits in Groups 4, 5 and 6 received intravitreal bevacizumab of 0.3 mg, 0.5 mg and 1.5mg/eye, respectively, after gas compression vitrectomy. Two weeks after the procedure, the rabbits were euthanized. Retina tissue samples were then obtained and examined with both light and electron microscopes. In Groups 1, 2 and 3 after bevacizumab injection, toxic degeneration in the photoreceptor and retinal pigment epithelium cells was observed via electron microscopic examination. The findings in Groups 4 and 5 were normal as compared to the control group. In Group 6, toxicity in the bipolar neurons and photoreceptor cells was noticed. Increased toxicity and retinal penetration were noticed in all administered doses of bevacizumab in the presence of vitreous. In addition, ocular toxicity occurred through the injection of the highest dose of bevacizumab after vitrectomy. It is possible that the bevacizumab dose and the, vitreous are as important as the drug half-life in the vitreous.

scholarly journals Mice Deficient in the Axonemal Protein Tektin-t Exhibit Male Infertility and Immotile-Cilium Syndrome Due to Impaired Inner Arm Dynein Function

2004 ◽  
Vol 24 (18) ◽  
pp. 7958-7964 ◽  
Author(s):  
Hiromitsu Tanaka ◽  
Naoko Iguchi ◽  
Yoshiro Toyama ◽  
Kouichi Kitamura ◽  
Tohru Takahashi ◽  
...  
Keyword(s):  
Physiological Role ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Vitro Fertilization ◽  
Homozygous Mutant ◽  
Causal Genes ◽  
And Function ◽  
Ciliary Dyskinesia

ABSTRACT The haploid germ cell-specific Tektin-t protein is a member of the Tektin family of proteins that form filaments in flagellar, ciliary, and axonemal microtubules. To investigate the physiological role of Tektin-t, we generated mice with a mutation in the tektin-t gene. The homozygous mutant males were infertile, while the females were fully fertile. Sperm morphology and function were abnormal, with frequent bending of the sperm flagella and marked defects in motility. In vitro fertilization assays showed that the defective spermatozoa were able to fertilize eggs. Electron microscopic examination showed that the dynein inner arm structure was disrupted in the sperm flagella of tektin-t-deficient mice. Furthermore, homozygous mutant mice had functionally defective tracheal cilia, as evidenced by altered dynein arm morphology. These results indicate that Tektin-t participates in dynein inner arm formation or attachment and that the loss of Tektin-t results in impaired motility of both flagella and cilia. Therefore, the tektin-t gene is one of the causal genes for immotile-cilium syndrome/primary ciliary dyskinesia.

The development of hepatic drug-metabolizing enzymes in perinatal guinea pigs: A biochemical and morphological study

1978 ◽  
Vol 56 (7) ◽  
pp. 738-745 ◽  
Author(s):  
D. J. Ecobichon ◽  
R. W. Dykeman ◽  
M. M. Hansell
Keyword(s):  
Guinea Pigs ◽  
Morphological Study ◽  
Smooth Endoplasmic Reticulum ◽  
Electron Microscopic Examination ◽  
Hepatic Enzymes ◽  
Electron Microscopic ◽  
Metabolizing Enzymes ◽  
Hepatic Drug ◽  
Enzymatic Systems ◽  
Functionally Diverse

The development of four functionally diverse, hepatic enzymes (p-nitroanisole O-demethylase, aniline hydroxylase, carboxylesterase, and glucuronyltransferase (with α-naphthol as the aglycone acceptor)) was studied in perinatal Hartley guinea pigs from 8 days prepartum to 28 days postpartum. A good correlation was observed between the activities measured in resuspended Ca2+-aggregated microsomes and the quantities of hepatic smooth endoplasmic reticulum visible by electron microscopic examination at the different stages of development. The study demonstrated that, postnatally, the guinea pig developed competent enzymatic systems as rapidly as did other laboratory species but that, prenatally, these same enzyme(s) systems were much further advanced than those in other species.

scholarly journals Are cross-bridging structures involved in the bundle formation of intermediate filaments and the decrease in locomotion that accompany cell aging?

1985 ◽  
Vol 100 (5) ◽  
pp. 1466-1473 ◽  
Author(s):  
E Wang
Keyword(s):  
Intermediate Filaments ◽  
Electron Microscopic Examination ◽  
Time Lapse ◽  
Cell Aging ◽  
Electron Microscopic ◽  
Cell Locomotion ◽  
Wide Range ◽  
Filament Bundles ◽  
Large Filament

Five different fibroblast strains derived from donors of a wide range of ages were used for investigation of senescence-associated changes in the organization of intermediate filaments (IFs) and the activity of cell locomotion. Results of immunofluorescence microscopy demonstrate that, in large and flat in vitro aged fibroblasts, vimentin-containing IFs are distributed as unusually organized large bundles. Electron microscopic examination shows that these large bundles are indeed composed of filaments of 8-10 nm. Such a profile of large bundles is rarely seen in young fibroblasts whose IFs are usually interdispersed among microtubules. Within the large filament bundles of senescent fibroblasts, cross-bridge-like extensions are frequently observed along the individual IFs. Immunogold labeling with antibody to one of the cross-bridging proteins, p50, further illustrates the abundance of interfilament links within the IF bundles. The senescence-related increase in interfilament association was also supported by the results of co-precipitation between vimentin and an associated protein of 50,000 D. Time-lapse cinematographic studies of cell locomotion reveal that accompanying aging, fibroblasts have a significantly reduced ability to translocate across a solid substratum. These results led me to suggest that the increased interfilament links via cross-bridges may in part contribute to the mechanism that orchestrates the formation of large filament bundles. The presence of enormous bundles in the cytoplasm may physically impede the efficiency of locomotion for these nondividing cells.

Massive liver enlargement accompanied by decreased drug metabolism. Effect of anterior pituitary extract on hepatic ultrastructure, zoxazolamine paralysis, and metabolism in the rat

1977 ◽  
Vol 55 (5) ◽  
pp. 1135-1142 ◽  
Author(s):  
S. Szabo ◽  
B. D. Garg ◽  
P. Kourounakis ◽  
B. Tuchweber
Keyword(s):  
Endoplasmic Reticulum ◽  
Drug Metabolism ◽  
Anterior Pituitary ◽  
Smooth Endoplasmic Reticulum ◽  
Electron Microscopic Examination ◽  
Liver Weight ◽  
Female Rats ◽  
Supernatant Fraction ◽  
Electron Microscopic ◽  
Liver Enlargement

The relationship between liver enlargement and drug metabolism was investigated in female rats. Hepatomegaly (e.g., 31% increase in liver weight in a 17-day experiment) was induced by injection of lyophylized anterior pituitary (LAP) extract The liver enlargement seemed to be due to an increase in the number and the size (enhanced water content and PAS-positive material) of hepatocytes. Electron microscopic examination of the liver revealed slight proliferation of the smooth endoplasmic reticulum and pronounced fragmentation and dilation of the rough endoplasmic reticulum. Zoxazolamine paralysis time was significantly prolonged (+55% and +102%) after 4 and 17 days, respectively, of treatment with LAP. Metabolism of zoxazolamine by the 9000 g supernatant fraction of the liver of rats given LAP for 17 days was reduced by 73%. Thus, the marked hepatomegaly induced by LAP was associated with a prolonged action of the drug which may result from a decrease in hepatic drug metabolism.

scholarly journals Polymerizing Microtubules Activate Site-directed F-Actin Assembly in Nerve Growth Cones

1999 ◽  
Vol 10 (7) ◽  
pp. 2309-2327 ◽  
Author(s):  
M. William Rochlin ◽  
Michael E. Dailey ◽  
Paul C. Bridgman
Keyword(s):  
Plasma Membrane ◽  
Actin Filaments ◽  
Cytochalasin B ◽  
Membrane Surface ◽  
Growth Cones ◽  
Actin Assembly ◽  
Electron Microscopic ◽  
Early Step ◽  
Microscopic Studies ◽  
Nerve Growth Cones

We identify an actin-based protrusive structure in growth cones termed “intrapodium.” Unlike filopodia, intrapodia are initiated exclusively within lamellipodia and elongate in a continuous (nonsaltatory) manner parallel to the plane of the dorsal plasma membrane causing a ridge-like protrusion. Intrapodia resemble the actin-rich structures induced by intracellular pathogens (e.g.,Listeria) or by extracellular beads. Cytochalasin B inhibits intrapodial elongation and removal of cytochalasin B produced a burst of intrapodial activity. Electron microscopic studies revealed that lamellipodial intrapodia contain both short and long actin filaments oriented with their barbed ends toward the membrane surface or advancing end. Our data suggest an interaction between microtubule endings and intrapodia formation. Disruption of microtubules by acute nocodazole treatment decreased intrapodia frequency, and washout of nocodazole or addition of the microtubule-stabilizing drug Taxol caused a burst of intrapodia formation. Furthermore, individual microtubule ends were found near intrapodia initiation sites. Thus, microtubule ends or associated structures may regulate these actin-dependent structures. We propose that intrapodia are the consequence of an early step in a cascade of events that leads to the development of F-actin-associated plasma membrane specializations.

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