Developmental Changes in the Interference Reflectors and Colorations of Tiger Beetles (Cicindela)

Samples of cicindelid cuticle were examined at various stages of adult ecdysis. The multilayered potential reflector was secreted in the initial stages of the moult, verifying that it is not tectocuticle and supporting the contention that it is a form of inner epicuticle. At early stages of ecdysis, the electron-dense layers were visible only when the section was post-stained. During post-ecdysial colour development, the dense layer increased in inherent electron density. Concurrently, the reflector increased in refractive index and the interference coloration increased in intensity and wavelength of maximum reflectance. Black pigment was also deposited simultaneously within the outer portion of the cuticle. It is proposed that electron-dense material was deposited in situ within the inner epicuticle after ecdysis, thereby increasing the wavelength and reflectance of interference colour.

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The Ultrastructure of the Epicuticular Interference Reflectors of Tiger Beetles (Cicindela)

Journal of Experimental Biology ◽

10.1242/jeb.117.1.87 ◽

1985 ◽

Vol 117 (1) ◽

pp. 87-110

Author(s):

T.D. SCHULTZ ◽

M.A. RANKIN

Keyword(s):

Refractive Index ◽

Dense Material ◽

Dense Layer ◽

Surface Reflectance ◽

Structural Coloration ◽

Electron Dense Material ◽

Tiger Beetles ◽

Electron Lucent

Tiger beetles of the genus Cicindela exhibit iridescent structural coloration due to the presence of a non-ideal multilayer interference reflector located in the outermost 2 μm of the integument. The reflector is composed of alternating layers of electron-lucent and electron-dense material. This series of layers was distinguished from chitinous procuticle by its position, ultrastructure and solubility in dilute KOH. The reflector appears homologous with the inner epicuticle of current models. Measurements of surface reflectance, refractive index and the dimensions of the alternating layers suggests that the dense layer has a refractive index (RI) near 2.0 and may be a melanoprotein.

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The ultrastructure of M1-a-mediated resistance to powdery mildew infection in barley

Canadian Journal of Botany ◽

10.1139/b75-286 ◽

1975 ◽

Vol 53 (22) ◽

pp. 2589-2597 ◽

Cited By ~ 10

Author(s):

H. H. Edwards

Keyword(s):

Powdery Mildew ◽

Host Cell ◽

Electron Density ◽

Epidermal Cells ◽

Dense Material ◽

Ultrastructural Changes ◽

Electron Dense Material ◽

Host Cytoplasm ◽

Powdery Mildew Infection ◽

Cell Protoplast

M1-a-mediated resistance in barley to invasion by the CR3 race of Erysiphe graminis f. sp. hordei does not occur in every host cell with the same speed and severity. In some cells ultrastructural changes within the host cell as a result of resistance will occur within 24 h after inoculation, whereas in other cells these changes may take up to 72 h. In some cells the ultrastructural changes are so drastic that they give the appearance of a hypersensitive death of the host cell, whereas in other cells the changes are very slight. In any case, at the end of these changes the fungus ceases growth. The ultrastructural changes occur in penetrated host epidermal cells as well as non-infected adjacent epidermal and mesophyll cells.The following ultrastructural changes have been observed: (1) an electron-dense material which occurs either free in the vacuole or adhering to the tonoplast (the material is granular or in large clumps); (2) an increased electron density of the host cytoplasm and nucleus; (3) a breakdown of the tonoplast so that the cytoplasmic constituents become dispersed throughout the cell lumen; and (4) the deposition of papillar-like material in areas other than the penetration site. The first three changes take place within the host cell protoplasts and are directly attributable to the gene M1-a. These changes are typical of stress or incompatibility responses and thus M1-a appears to trigger a generalized incompatibility response in the presence of race CR3. The papillar-like material occurs outside the host cell protoplast in the same manner as the papilla and probably is not directly attributable to M1-a.

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The ultrastructure of the epidermis of Diplectanum aequans (Monogenea)

Parasitology ◽

10.1017/s0031182000000470 ◽

1980 ◽

Vol 80 (1) ◽

pp. 9-21 ◽

Cited By ~ 9

Author(s):

M. K. Shaw

Keyword(s):

Outer Membrane ◽

Electron Density ◽

Dense Material ◽

Small Scale ◽

Electron Dense Material ◽

Granular Cytoplasm ◽

Outer Epidermis

SummaryThe epidermis of Diplectanum aequans has, in general, been found to be similar to the epidermis of other monogeneans, consisting of a syncytial outer epidermis and sunken sub-epidermal nucleated regions. However, the epidermis of D. aequans differs from that of other monogeneans in 3 respects. These are, the presence of large areas of granular cytoplasm within the outer epidermis, the presence of myofibres invaginating into the epidermal matrix and, in the posterior regions of the epidermis, the presence of epidermal scales. These scales occur within the epidermal cytoplasm, beneath the outer membrane, and are composed of moderately electron-dense material. Also present beneath the outer membrane in the more anterior regions of the epidermis are small scale-like sclerites of a similar electron density to the epidermal scales.

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Ultrastructural variations of the urothelial membrane in essential fatty acid (EFA)-deficient rats. A digital densitometric study.

Journal of Histochemistry & Cytochemistry ◽

10.1177/34.12.3782776 ◽

1986 ◽

Vol 34 (12) ◽

pp. 1639-1644 ◽

Cited By ~ 2

Author(s):

F Kalinec ◽

J H Calderón ◽

B Monis

Keyword(s):

Electron Density ◽

Present Report ◽

Dense Material ◽

Transitional Epithelium ◽

Unit Membrane ◽

Experimental Conditions ◽

Electron Dense Material ◽

Outer Leaflet ◽

Photodiode Array ◽

Computer Controlled

The present report deals with a densitometric study of the ultrastructural images of the urothelial membrane of rats in the following experimental conditions: (1) EFA-deficient (EFAD) rats; (2) EFA-sufficient (EFAS) rats; and (3) EFAD rats that were fed the EFAD diet for 30 weeks and received an EFAS diet for the following 10 weeks (EFAD/S group). On electron micrographs of the transitional epithelium of ureters and urinary bladder of these rats, optical density (OD) profiles of the urothelial unit membrane were recorded and digitized using a computer-controlled microdensitometer with a solid-state self-scanned photodiode array sensor. A Gaussian curve was adopted as a model for the distribution of electron-dense material in each osmiophilic leaflet. Gaussian parameters were used to estimate the thickness of the urothelial membrane and of each osmiophilic leaflet, and the amount of electron-dense material and the maximal electron density present in each leaflet. In EFAS rats, the thick urothelial membrane was asymmetric like that of the normal, resulting from a greater thickness of the outer leaflet and a greater electron density of the cytoplasmic one. In EFAD rats, a loss of the characteristic ultrastructural asymmetry and a decrease of the total thickness of the unit membrane were detected. These changes were partially reversed in the EFAD/S rats.

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Studies on the mechanism of circus movement in dissociated embryonic cells of a teleost, Oryzias latipes: fine-structural observations

Journal of Cell Science ◽

10.1242/jcs.22.1.133 ◽

1976 ◽

Vol 22 (1) ◽

pp. 133-147

Author(s):

N. Fujinami

Keyword(s):

Cytochalasin B ◽

Oryzias Latipes ◽

Cortical Layer ◽

Dense Material ◽

Dense Layer ◽

Cell Periphery ◽

Embryonic Cells ◽

Advancing Front ◽

Circus Movement

The fine structure of lobopodia in dissociated embryonic cells of the freshwater fish, Oryzias latipes, was observed with the electron microscope in order to understand the mechanism of the circus movements which they display. Dense material (grandular or fibrillar) is present in the zone between the lobopodium and the endoplasm, as well as in the cortical layer around the cell circumference. The direction of lobopodial movement is related to the distribution of this dense material. The band between the lobopodium and the endoplasm is conspicuous and is connected to the cortical dense layer around the cell periphery at the advancing front of the lobopodium, while the dense material is usually almost absent beneath the cell membrane in the anterior region of the lobopodium. The band between lobopodium and endoplasm is blurred or disrupted near the hind end of the lobopodiu, where the peripheral dense layer is well developed. In situ localization of actin/heavy meromyosin complexes in the cell showed that the dense material has actin-like properties. Cytochalasin B(0-5 mug/ml) induced constriction of the neck of the bleb, shrinkage of the endoplasm, and herniation of the endoplasmic contents to the enlarged hemispherical bleb, and thus arrested the circus movement. On the basis of these results, an hypothesis concerning the mechanism of circus movement is proposed and discussed.

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Fine structure of surface and sunken grooved pegs on the antenna of female Anopheles stephensi (Diptera: Culicidae)

Canadian Journal of Zoology ◽

10.1139/z76-026 ◽

1976 ◽

Vol 54 (2) ◽

pp. 235-244 ◽

Cited By ~ 14

Author(s):

K. S. Boo ◽

S. B. McIver

Keyword(s):

Fine Structure ◽

Electron Density ◽

Anopheles Stephensi ◽

Olfactory Receptors ◽

The Other ◽

Dense Material ◽

Extracellular Material ◽

Electron Dense Material ◽

Subtype B ◽

Antenna Surface

The antenna of female Anopheles stephensi Liston bears three types of sensilla with grooved pegs: those sunken in pits and subtypes A and B of those located on the flagellar surface. The sunken peg sensilla are innervated by four or five neurons with branching dendrites. The dendrites are exposed to the exterior by means of longitudinal clefts at the bases of the grooves in the peg wall. Surrounding the dendrites and extending into the clefts is an extracellular material of medium electron density. Three sheath cells are associated with each sunken peg sensillum.Subtype-A surface peg sensilla are generally similar to the sunken peg sensilla, except that they are located on the antenna) surface and are innervated by two neurons with unbranched dendrites. Subtype-B surface peg sensilla have three or four neurons, the dendrites of which do not branch and are exposed less to the exterior than those in the other peg sensilla because the clefts in the peg wall are smaller and less frequent. Only trace amounts of electron-dense material occur in the clefts of the subtype-B surface peg sensilla.The sunken peg and both subtypes of the surface peg sensilla are probably olfactory receptors.

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Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068631 ◽

1970 ◽

Vol 28 ◽

pp. 328-329

Author(s):

J. R. Ruby ◽

R. F. Dyer ◽

R. G. Skalko ◽

R. F. Gasser ◽

E. P. Volpe

Keyword(s):

Germ Cells ◽

Rana Pipiens ◽

Comparative Morphology ◽

Dense Material ◽

Individual Species ◽

Microscope Examination ◽

Electron Dense Material ◽

Intercellular Bridges ◽

Cytoplasmic Side ◽

Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

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Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19802219 ◽

1980 ◽

Vol 45 (8) ◽

pp. 2219-2223 ◽

Cited By ~ 6

Author(s):

Marie Jakoubková ◽

Martin Čapka

Keyword(s):

Catalytic Activity ◽

Nmr Spectroscopy ◽

Ir Spectroscopy ◽

Electron Density ◽

Phosphorus Atom ◽

Proton Acceptor ◽

Trimethylsilyl Group ◽

Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

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Strong equatorial plasma bubble associated with prominent TEC enhancement observed at mid-latitude ionosphere under the quiescent condition

10.5194/egusphere-egu21-3832 ◽

2021 ◽

Author(s):

Fuqing Huang ◽

Jiuhou Lei ◽

Chao Xiong

Keyword(s):

Electron Density ◽

Electron Content ◽

Radio Waves ◽

Plasma Bubble ◽

Total Electron ◽

Middle Latitudes ◽

Multiple Observations ◽

Equatorial Plasma Bubbles ◽

Low Latitudes

<p>Equatorial plasma bubbles (EPBs) are typically ionospheric irregularities that frequently occur at the low latitudes and equatorial regions, which can significantly affect the propagation of radio waves. In this study, we reported a unique strong EPB that happened at middle latitudes over the Asian sector during the quiescent period. The multiple observations including total electron content (TEC) from Beidou geostationary satellites and GPS, ionosondes, in-situ electron density from SWARM and meteor radar are used to explore the characteristic and mechanism of the observed EPB. The unique strong EPB was associated with great nighttime TEC/electron density enhancement at the middle latitudes, which moves toward eastward. The potential physical processes of the observed EPB are also discussed.</p>

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