scholarly journals A NEW APICAL MICROTUBULE-ASSOCIATED ORGANELLE IN THE STERNAL GLAND OF ZOOTERMOPSIS NEVADENSIS (HAGEN), ISOPTERA

1965 ◽  
Vol 24 (2) ◽  
pp. 277-283 ◽  
Author(s):  
P. Satir ◽  
A. M. Stuart
Keyword(s):  
Electron Microscope ◽  
Cell Membrane ◽  
Cell Organelle ◽  
Sternal Gland ◽  
Opaque Zone ◽  
Cell Cytoplasm ◽  
Apical Portion ◽  
Smooth Membrane ◽  
Membrane Bound ◽  
Columnar Cells

The apical portion of the columnar cells of the sternal gland of the termite Zootermopsis nevadensis (Hagen) has been examined with the electron microscope. The cell surface abutting the cuticle is thrown into ridges upon which stand microvilli. Sections show a network of smooth membrane-bound cisternae penetrating the interior of the microvilli. At the bottom of the crevasses between the ridges, an inpocketing of the cell membrane is often found. This is surrounded by a 40-mµ electron-opaque zone that is the insertion of a 22-mµ microtubular component of the cell cytoplasm. The pouch-like structures and their associated microtubules are considered to represent a new cell organelle.

scholarly journals ELECTRON MICROSCOPE STUDIES ON THE CELLS OF THE MALPIGHIAN TUBULES OF THE GRASSHOPPER (ORTHOPTERA, ACRIDIDAE)

1955 ◽  
Vol 1 (3) ◽  
pp. 197-202 ◽  
Author(s):  
H. W. Beams ◽  
T. N. Tahmisian ◽  
R. L. Devine
Keyword(s):  
Electron Microscope ◽  
Cell Membrane ◽  
Cell Body ◽  
Basal Cell ◽  
Brush Border ◽  
Malpighian Tubules ◽  
Cell Cytoplasm ◽  
Small Bodies ◽  
Dense Cores ◽  
Basal Zone

For purposes of description, the cells of the Malpighian tubules of the grasshopper may be divided into basal, intermediate, and apical zones. The basal zone of the cell contains what appears to be an elaborate infolding of the cell membrane at the base. This condition results in the basal cell cytoplasm being divided into many compartments. The compartments contain mitochondria that are often arranged in rows. Other small bodies which possess relatively dense outer borders and less dense cores were observed within the compartments. These bodies are unidentified. The brush border of the apical zone contains a multitude of vertically arranged protoplasmic processes. Stages were found which suggest that the filamentous mitochondria migrate from the cell body to the base of the protoplasmic processes, where they enter them and move apically. Some of the mitochondria were observed at the very tips of the processes where they enlarge producing an accompanying bulging of the tips. This condition is interpreted as a stage in the pinching off of the mitochondria-laden tips of the protoplasmic processes.

scholarly journals Degradation of aggrecan precursors within a specialized subcompartment of the chicken chondrocyte endoplasmic reticulum

1996 ◽  
Vol 316 (2) ◽  
pp. 487-495 ◽  
Author(s):  
Manuel ALONSO ◽  
Josefina HIDALGO ◽  
Linda HENDRICKS ◽  
Angel VELASCO
Keyword(s):  
Endoplasmic Reticulum ◽  
Protease Inhibitors ◽  
Degradation Rate ◽  
Redox State ◽  
Brefeldin A ◽  
Lag Phase ◽  
Cysteine Protease Inhibitors ◽  
Immunofluorescence Analysis ◽  
Smooth Membrane ◽  
Membrane Bound

Chicken chondrocytes in culture synthesize aggrecan proteoglycan as a 370 kDa precursor that is glycosylated and secreted into the medium with a half-life of 30 min. In metabolic studies the 370 kDa precursor was shown to render a degradation intermediate of 190 kDa, which appeared with no measurable lag phase; it was dependent on temperature (> 20 °C) and inhibited by certain serine and serine/cysteine protease inhibitors such as leupeptin and PMSF. By contrast, degradation was unaffected by treatment of the cells with brefeldin A or with lysosomotropic agents. Aggrecan precursors were detected by immunofluorescence analysis within a subcompartment of the endoplasmic reticulum (ER), previously characterized as a smooth-membrane-bound subregion [Vertel, Velasco, LaFrance, Walters and Kaczman-Daniel (1989) J. Cell Biol. 109, 1827–1836]. Analysis of the subcellular fractions derived from chondrocytes indicated that the degradation intermediate was concentrated in the ER subcompartment. Degradation was dependent on the Ca2+ concentration and the redox state in the ER. Treatment of the cells with agents or conditions that alter the degradation rate of aggrecan precursors, such as protease inhibitors, decreased temperature or dithiothreitol, also modified the retention of these molecules in the ER subcompartment, as seen by immunofluorescence. These results indicate that a fraction of the 370 kDa aggrecan precursor is targeted to a smooth ER subcompartment where it undergoes degradation.

scholarly journals Two Atypical Enteropathogenic Escherichia coli Strains Induce the Production of Secreted and Membrane-Bound Mucins To Benefit Their Own Growth at the Apical Surface of Human Mucin-Secreting Intestinal HT29-MTX Cells

2010 ◽  
Vol 78 (3) ◽  
pp. 927-938 ◽  
Author(s):  
Mônica A. M. Vieira ◽  
Tânia A. T. Gomes ◽  
Antonio J. P. Ferreira ◽  
Terezinha Knöbl ◽  
Alain L. Servin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Brush Border ◽  
Apical Surface ◽  
Enteropathogenic Escherichia Coli ◽  
Typical Epec ◽  
Membrane Bound

ABSTRACT In rabbit ligated ileal loops, two atypical enteropathogenic Escherichia coli (aEPEC) strains, 3991-1 and 0421-1, intimately associated with the cell membrane, forming the characteristic EPEC attachment and effacement lesion of the brush border, induced a mucous hypersecretion, whereas typical EPEC (tEPEC) strain E2348/69 did not. Using cultured human mucin-secreting intestinal HT29-MTX cells, we demonstrate that apically aEPEC infection is followed by increased production of secreted MUC2 and MUC5AC mucins and membrane-bound MUC3 and MUC4 mucins. The transcription of the MUC5AC and MUC4 genes was transiently upregulated after aEPEC infection. We provide evidence that the apically adhering aEPEC cells exploit the mucins' increased production since they grew in the presence of membrane-bound mucins, whereas tEPEC did not. The data described herein report a putative new virulence phenomenon in aEPEC.

An Electron Microscope study of a Small Free-living Amoeba (Hartmanella astronyxis)

1959 ◽  
Vol s3-100 (49) ◽  
pp. 13-15
Author(s):  
K. DEUTSCH ◽  
M. M. SWANN
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Cell Membrane ◽  
Nuclear Membrane ◽  
Layered Structure ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Honeycomb Structure ◽  
Free Living ◽  
Free Living Amoeba

The fine structure of a species of small free-living amoeba, Hartmanella astronyxis, has been investigated. The mitochondria resemble those of other species of amoeba. Structureless bodies of about the same size as mitochondria are sometimes found in association with them. Double membranes are common in the cytoplasm, and may show granules along their outer borders. The nuclear membrane is a double-layered structure, with a honeycomb structure evident in tangential sections. The cell membrane is also double-layered, or occasionally multi-layered.

Fourier-transform detection of singlet oxygen and fluorescence from cell membrane bound porphyrins

1994 ◽  
Vol 90 (17) ◽  
pp. 2453-2454 ◽  
Author(s):  
Fritz Böhm ◽  
George Marston ◽  
T. George Truscott ◽  
Richard P. Wayne
Keyword(s):  
Fourier Transform ◽  
Cell Membrane ◽  
Singlet Oxygen ◽  
Membrane Bound

scholarly journals An Electron Microscope Study of the Source and Distribution of Ferritin in Hepatic Parenchymal Cells of the Newborn Rabbit

Blood ◽  
1960 ◽  
Vol 15 (4) ◽  
pp. 480-490 ◽  
Author(s):  
JAMES C. HAMPTON
Keyword(s):  
Electron Microscope ◽  
Microscope Study ◽  
Light Microscope ◽  
Electron Microscope Study ◽  
Hepatic Cell ◽  
Cell Cytoplasm ◽  
Electron Microscopic ◽  
Newborn Rabbit ◽  
Blue Reaction ◽  
Parenchymal Cells

Abstract Evidence that erythrocytes are phagocytized and dismantled by hepatic parenchymal cells in the newborn rabbit is presented. It is concluded that in these cells iron is recovered from disintegrating erythrocytes, synthesized into ferritin and released into the hepatic cell cytoplasm and into the biliary passages. These conclusions are based upon observations on the distribution of material giving the Prussian blue reaction in sections of liver as revealed by the light microscope and upon electron microscopic images of particles displaying the size, density and configuration of the ferritin molecule.

Identification and properties of the cell membrane bound leucine aminopeptidase interacting with the potential immunostimulant and chemotherapeutic agent bestatin

1983 ◽  
Vol 32 (6) ◽  
pp. 1051-1057 ◽  
Author(s):  
G. Leyhausen ◽  
D.K. Schuster ◽  
P. Vaith ◽  
R.K. Zahn ◽  
H. Umezawa ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Leucine Aminopeptidase ◽  
Chemotherapeutic Agent ◽  
Membrane Bound

Ultrastructure of tobacco mosaic virus lesions and surrounding tissue in Phaseolus vulgaris var. Pinto

1971 ◽  
Vol 49 (3) ◽  
pp. 417-421 ◽  
Author(s):  
D. F. Spencer ◽  
W. C. Kimmins
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Phaseolus Vulgaris ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Healthy Tissue ◽  
Surrounding Tissue ◽  
Infected Area ◽  
Membrane Bound

Leaves of Phaseolus vulgaris var. Pinto were inoculated with the U1 strain of tobacco mosaic virus TMV (U1) and fully expanded lesions and adjacent healthy tissue were examined in the electron microscope. Emphasis was placed on the band of healthy cells (resistant zone) surrounding the lesion, with the object of detecting the first changes in ultrastructure as healthy tissue graded into the infected area. Cells in the resistant zone were characterized by the appearance of membrane-bound vesicular bodies (paramural bodies) between the plasmalemma and cell wall. Where paramural bodies accumulated, the plasmalemma was withdrawn and intercellular cytoplasmic connections through the plasmodesmata were severed. These changes were found most frequently for a distance of about three cell diameters beyond cells visibly infected at the lesion periphery. It is suggested that these changes in ultrastructure are related to the events of localization. Spread of the virus may be inhibited because of a lack of cytoplasmic connections between cells surrounding the virus-induced lesion.

Sheaths of the Motor Axons of the Crab Carcinus

1964 ◽  
Vol s3-105 (70) ◽  
pp. 175-181
Author(s):  
G. A. HORRIDGE ◽  
R. A. CHAPMAN
Keyword(s):  
Cell Membrane ◽  
Glial Cell ◽  
Cross Section ◽  
Glial Cells ◽  
Fibrous Material ◽  
Motor Axons ◽  
Cell Cytoplasm ◽  
Fibrous Sheath ◽  
Outer Sheath ◽  
Sheath Structure

In crab leg nerves, the largest axons, which are the motor axons usually isolated for physiological experiments, have a sheath structure which is different from that in medium sized and smaller axons of the same nerve or of any other described nerves. Axons with a diameter over 20 µ have (a) an outer sheath, about 5µ thick, of wellspaced layers of alternating glial cell cytoplasm and extracellular fibrous material, formed from fewer cells than there are layers, and (b) an inner sheath of elongated cells which creep along the axon longitudinally and interdigitate where they meet, as seen 2 or 3 times round the outside of the membranes of axons in cross-section. Therefore, possible channels between inner glial cells are elongated and few. On these structural grounds, together with physiological evidence, they seem unlikely to be preferred pathways of diffusion of ions in crab axons. Smaller axons have simple sheaths; some occur in groups within a fibrous sheath; the thinnest axons frequently occur in bundles and have no glial cell membrane in contact with them.

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