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PubMed1978

Ultrastruct of the hypothalamic neurosecretory nuclei of the dormouse (Eliomys quercinus L.) in the awakening and hibernating states.

The ultrastructure of the chief neurosecretory nuclei, supraoptic, (SON), parventricular, (PVN) and infundibular (IN), of the dormouse (Eliomys quercinus L.) has been studied during active and hibernating states. In the active state all three nuclei contained light, dark and intermediate type neurons. In hibernation the SON showed only a single light type which differed from the light neurons of the active state; the endoplasmic reticulum was vacuolized and sometimes grouped in 'honey-comb' structures; the cytoplasm contained accumulations of filamentous 'crystalline' material. None of these features occurred in the active state neurons. In the PVN and IN during hibernation both a light and a dark type neuron were present. 'Honey-comb' structures were seen in neurons of the PVN during hibernation, but never in those of the IN. Thus specific morphological features in the SON and PVN appear to be associated with the physiological changes of hibernation.

Animals↗
PubMed1978

Ultrastructural features and glycogen distribution in the electric organ of the electric ray Torpedo marmorata L.

The ultrastructural topography of glycogen in the electic organ of the fish Torpedo marmorata has been examined following Thiéry's method and the modified osmium tetroxide post-fixation of De Bruijn. Both methods reveal a high concentration of glycogen particles in the nerve terminals, particularly in pedunculate pouches issuing from the nerve endings and bulging into the intersyncytial area. A few sparse positive particles are scattered at random in the Schwann cells and in the cuff cells occasionally encapsulating the myelinated and ummyelinated subsynaptic axons. In the electric cell, glycogen occurs in the form of scattered particles homogenously distributed among all the cytoplasm. The structure and the size of glycogen granules in relation to the detection methods used and to previous parallel investigations are briefly discussed.

Animals↗
PubMed1996

The plasma and cytoplasmic forms of human gelsolin differ in disulfide structure.

Gelsolin is a widely distributed actin binding protein that regulates actin filament length. It exists in both an intracellular and an extracellular form that is derived from a single gene by alternative splicing. Both forms contain the six homologous domains that are responsible for function. Little is known regarding differences between the forms. We have used a combination of cysteine-specific modification with 4-vinylpyridine, HPLC peptide mapping methods, and mass spectrometry to analyze the disulfide structures of human plasma and cytoplasmic gelsolin. Of the five Cys residues in the human gelsolin sequence, all were present in the free thiol form in human cytoplasmic gelsolin, while only three of them were free thiols in the human plasma form. Cys residues 188 and 201 in domain 2 of plasma gelsolin were disulfide linked. Recombinant human plasma gelsolin that had been expressed intracellularly in Escherichia coli and as a secreted protein from Cos green monkey cells was also investigated. The E. coli product lacked the disulfide but could be converted to the plasma-like structure with mild oxidation while the mammalian product formed the correct disulfide prior to isolation. Structural differences were also detected by limited proteolysis with plasmin. The differences in proteolytic susceptibility were also due to perturbations in domain 2. These studies demonstrate that the intracellular and extracellular gelsolins are structurally distinct and suggest that at least some of the preparations of recombinant gelsolin that are being used to study structure/function may be improperly folded. The experiments also demonstrate a general method for the location of disulfide bonds in proteins.

Actins↗
PubMed1978

Fine structure of the eyes of orb-weavers, Argiope amoena L. Koch (Aranea: Argiopidae). 2. The anterolateral, posterolateral and posterommedial eyes.

The anterolateral eye, the posterolateral eye and the posteromedial eye of the web-building spider, Argiope amoena have been examined by light and electron microscopy. The dioptric apparatus of all three eyes is similar in structure, and consists of a cornea, a lens and a vitreous body. The retina contains monopolar receptor cells, the cell bodies of which are present beneath the vitreous body in all three eyes. Proximal processes of the receptor cells form rhabdoms beneath the cell body layer and then extend toward the first optic glomerulus as an ocellar nerve. Two distinct patterns of retinal organization are present in the three eyes. In one type the rhabdomic layer of the retina is backed by a pigmented layer. In the other type the rhabdomic layer is backed by a tapetal reflecting layer. Rhabdomic structure and cytoplasmic inclusions of the receptor cells differ greatly between the two types. The anterolateral eye possesses a single type of retina with the rhabdoms backed by the tapetum. Both the posterolateral and the posteromedial eye are similar in structure, each possessing beneath the common dioptric apparatus retinae of both types.

Animals↗
PubMed1993

Primary structure and cell-type specific expression of a gustatory G protein-coupled receptor related to olfactory receptors.

We have reported on the partial structures of a multigene family encoding GTP-binding protein (G protein)-coupled, seven-transmembrane receptors expressed in the tongue (Abe, K., Kusakabe, Y., Tanemura, K., Emori, Y., and Arai, S. (1993) FEBS Lett. 316, 253-256). Here we describe a full-length cDNA clone encoding a tongue cell-type specific receptor. The encoded protein consists of 312 amino acid residues. In overall structure, the protein is similar to known G protein-coupled, seven-transmembrane receptors such as an olfactory receptor (56% identity) but is significantly different in part, particularly in NH2-terminal extracellular and COOH-terminal cytoplasmic domain structures. Northern analysis showed that the mRNA for this protein is expressed only in the epithelium of the tongue, not in other organs. In situ hybridization experiments clearly indicated that the mRNA is expressed exclusively on the tongue apical surface, not on the reverse side of the tongue nor in its muscle layer. Expression was also detected in the taste buds and surrounding cellular tissues of the fungiform and circumvallate papillae. It is suggested that this gustatory receptor structurally related to olfactory receptors may be a candidate for a taste receptor.

Amino Acid Sequence↗
PubMed1994

Effects of anisosmotic conditions on the cytoskeletal architecture of cultured PC12 cells.

PC12 cells show a classical volume regulatory process when submitted to hypo-osmotic conditions. The present study examined the effects of such osmotic shock on the structural organization of different cytoskeletal elements. Results were obtained by use of different light and electron microscopy techniques combined with immunostaining methods. It appeared that the osmotically induced changes in cell volume were concomitant with important modifications in the organization of the microfilament network. Microfilaments concentrated in the perinuclear area, leaving only radial extensions of poorly organized structures in the cytoplasm. The latter were the only actin structures immunologically stained in the cytoplasm and seemed to anchor to the plasma membrane. Measurements of the fluorescence intensity of PC12 cells treated with FITC-labeled phalloidin indicated a progressive depolymerization, followed by a repolymerization of F-actin. This occurs in parallel with microfilament reorganization and volume regulatory processes. The appearance of microfilament reorganization was a function of both the incubation period and the amplitude of the osmolarity changes. During the first minutes of osmotic shock, a decrease was observed in the density and length of microvilli, which normally cover the PC12 cell surfaces, suggesting an early reorganization of the underlying microfilament network. Microtubules and intermediate filament networks were not affected by the hypo-osmotic conditions.

Actin Cytoskeleton↗
PubMed2006

Methamphetamine induces autophagy and apoptosis in a mesencephalic dopaminergic neuronal culture model: role of cathepsin-D in methamphetamine-induced apoptotic cell death.

Autophagy is a phylogenetically conserved process that plays a critical role in the degradation of oxidatively damaged proteins and organelle turnover. The role of oxidative stress and apoptosis in methamphetamine (METH)-induced neurotoxicity is well known; however, the potential contribution of autophagy to METH-induced oxidative damage in dopaminergic neuronal systems remains unclear. The goals of the present article were twofold: (a) to develop an in vitro dopaminergic cell culture model to study cellular and molecular mechanisms underlying METH-induced autophagy and apoptosis, and (b) to determine whether lysosomal protease cathepsin-D activation, resulting from the loss of lysosomal membrane integrity, contributes to METH-induced apoptosis. To accomplish these goals, we characterized morphological and biochemical changes in an immortalized mesencephalic dopaminergic neuronal cell line (N27 cells) following treatment with METH. Exposure of METH (2 mM) to N27 cells resulted in the appearance of cytoplasmic vacuolar structures reminiscent of autophagic vacuoles within 3 h. In order to ascertain the identity of the vacuolar structures that are formed following METH exposure, immunohistochemical staining for markers of autophagy were performed. LAMP 2, a classical marker of autophagolysosomes, revealed an extensive punctuate pattern of distribution on the vacuolar membrane surface, with exclusive localization in the cytoplasm. Additionally, using DNA fragmentation analysis we showed a dose-dependent increase in fragmented DNA in METH treated N27 cells. Since METH-induced autophagy preceded DNA fragmentation, we tested whether dysfunction of the autophagolysosomal system contributes to nuclear damage. Immunofluorescence studies with cathepsin-d demonstrated a granular pattern of staining in untreated cells, whereas an increased cathepsin- D immunoreactivity with a globular pattern of staining was observed in METH-treated cells. Nevertheless, blockade of cathepsin-D activation by pepstatin-A, cathepsin-D inhibitor, failed to alter METH-induced DNA fragmentation. Collectively, these results demonstrate that N27 dopaminergic neuronal cell model may serve as an excellent in vitro model to study the mechanisms of METH-induced autophagy and apoptosis. Furthermore, it is less likely that cathepsin-D may serve as a trigger for the induction of apoptosis subsequent to exposure of N27 dopaminergic neuronal cells to METH.

Animals↗
PubMed1964

AGE VARIATIONS IN CORTICAL MEMBRANES OF ROTIFERS.

Electron micrographs were made of rotifers of known ages embedded in Vestopal and stained with lead hydroxide. In epithelial cells lining the gut of the rotifer, anatomical continuity is seen between the cell membrane, the cortical membranes, and the rough endoplasmic reticulum at the basal region of the cells. At their luminal surface, these cells possess a terminal web, and colloidal gold is taken up via food vacuoles at this surface. Such pinocytosis does not occur on the peripheral or distal surface (pseudocoelomic) of these cells. Exposure of rotifers to adenine inhibits the formation of cortical infoldings of the cell membrane and the formation of the rough reticulum, whereas the ribosomes and the Golgi apparatus appear to be unaffected. The suggestion is made that the rough reticulum may be derived from modifications of the cell membrane and that the rate of formation of the rough reticulum in adult and elderly rotifers is lower than in the actively growing animal.

Aging↗
PubMed1975

Babesia sp.: the relationship of stage of development to structure of intra- and extracellular parasites.

The relationship of stage of development to structure in Babesia rodhaini and B. microti was studied by freeze-etching, carbon replication, and thin sectioning. The trophozoites of these Babesia are surrounded by a single membrane over most of their surfaces, but in some regions of the cytoplasm, membranous structures may parallel the plasmalemma, providing a double membrane. Merozoites are produced from trophozoites by budding. An early external indication that a bud will form is the organization of a pellicle complex at the site of the bud. The trophozoite nucleus divides before bud formation starts. The pellicle forms by development of a thick subplasmalemmal layer just under the plasmalemma in a bulging area that contains one of the daughter nuclei. The subplasmalemma layer of the pellicle of babesial merozoites is similar to that of plasmodial merozoites as it is divided into a series of roughly hexagonal plates by a reticular network which resembles coarse chicken wire. Thus, not only are the merozoites of these two species of Babesia budded in a fashion similar to that by which plasmodial merozoites are budded, but they also have similar pellicles.

Animals↗
PubMed2001

[Mechanisms of the effect of circulating neutrophils (granulocytes) in the response of a release reaction of human platelets].

Studied singularities of development platelet release reaction, as of functional activity platelets, at direct effect contents of cytoplasmic granular structures circulating neutrophile leucocytes (granulocytes), possessing a potential capability to selective exocytosis. The model researches were conducted in a system in vitro on isolated viable non active of platelets practically of healthy people. As possible activators the subpopulations them of cytoplasmic granules, distinguished on morphological and enzymetion to indications were applied, previously chosen by methods of an analytical centrifuging from donor neutrophile granulocytes. The development platelets of a response of a release was determined on dynamics quantitative reorganization in platelets an alpha-granules and change of activity in out of platelets to environment of the factor 4 platelets. The capability of a dominance lysosomal initiators neutrophile granulocytes in development of a response of a release of platelets was installed. The scheme of probable trigger participation circulating of neutrophile granulocytes in development syndrome disseminated intravascular coagulation.

Blood Coagulation↗
PubMed1992

Alterations of thyroid parafollicular cell organization in aged rats neonatally treated with estradiol.

Cellular and subcellular organization of parafollicular cells of aged male Wistar rats (180- and 365-day-old), neonatally (3rd day) treated with a single dose (1 mg) of oestradiol-dipropionate (OeDP), were studied. Based on argyrophil properties of parafollicular cells in control and treated group, two morphometrically distinct cell types were observed (under and over 50 microns 2 of cell area), reflecting distinct functional status of the same cell type. The first signs of hyperplastic changes in parafollicular cells were observed in 180-day-old rats and they were more severe in 365-day-old animals. Morphometric averages for the area of parafollicular cells and nuclei, as well as for the cell number in estradiol-treated animals were higher than in the controls, but these differences were statistically insignificant. However, subcellular organization of parafollicular cells showed that besides the cells with clearly visible characteristics such as control hyperplastic cells, there were parafollicular cells with progressively more abnormalities expressed as myelin-like figures, cytoplasmic cribriform structures and dilated endoplasmic reticulum (ER), demonstrating long-lasting effects of neonatally applied estradiol.

Aging↗
PubMed1957

Microkinetospheres and VP satellites of pinocytic cells observed in tissue cultures of Gey's strain HeLa with phase contrast cinematographic techniques.

By tissue culture methods and with the use of phase contrast, interference color contrast, and time-lapse cinematographic equipment, the activity of a cytoplasmic organoid, termed the microkinetosphere, has been followed and correlated with pinocytosis. A transformation of several microkinetospheres by coherence and coalescence into the solitary VP satellite was observed in cells undergoing pinocytosis in serum nutrients. A correlation of both of these structures to cytoplasmic organoids described by others, notably with the electron microscope, and a hypothesis on the nature of the microkinetosphere and its transformation was presented.

HeLa Cells↗
PubMed1986

Structural changes in the nucleoid of Bacillus subtilis at low temperature.

The external shape of the nucleoid of Bacillus subtilis strain w23 was examined with a new electron microscopic technique, the rapid freezing and substitution fixation method. The nucleoid of the log and stationary phase cells was recognized as an area devoid of ribosomes and widely dispersed in the cytoplasm, which was different from that observed in OsO4-fixed cells. If the bacteria were exposed to low temperatures (0 to 10 C), the nucleoid showed a highly concentrated shape in the middle of the cytoplasm. These structural changes were observed only when the bacteria were maintained in a high-salt buffer. The results are discussed in relation to the membrane fluidity at low temperature.

Bacillus subtilis↗
PubMed2000

[The structural organization of the vascular plexus of the endbrain in the human embryo at the 8th week of development].

Choroid plexus of human 8 wks old telencephalon embryo was studied using light and electron microscopy and immunocytochemistry. Precise description of epithelial cells and choroid plexus stroma ultrastructure is given as well as distribution of vimentine interstitial filaments in epithelial cells cytoplasm. The structure of choroid plexus blood vessels was studied. Smooth myocytes were not found in blood vessel wall. Vascular wall consists of single layer of endotheliocyte lacking basal membrane. At this stage of development endothelium was not fenestrated. Based on morphological data conclusions were made of fundamental condition of choroid plexus tissue elements.

Endothelium, Vascular↗