scholarly journals ULTRASTRUCTURE OF DNA-CONTAINING AREAS IN THE CHLOROPLAST OF CHLAMYDOMONAS

1962 ◽  
Vol 13 (3) ◽  
pp. 383-391 ◽  
Author(s):  
Hans Ris ◽  
Walter Plaut
Keyword(s):  
Acridine Orange ◽  
Electron Micrographs ◽  
Genetic System ◽  
Feulgen Reaction ◽  
Electron Microscopic ◽  
Chlamydomonas Moewusii

The chloroplast of Chlamydomonas moewusii was examined by electron microscopic and cytochemical methods for the possible presence of DNA. Both the Feulgen reaction and acridine orange indicated the presence within the chloroplast of one or more irregularly shaped DNA-containing bodies generally in the vicinity of the pyrenoid. Electron micrographs revealed 25 A microfibrils in these areas which correspond to DNA macromolecules with respect to their location, morphology, and sensitivity to deoxyribonuclease digestion. The possibility that this material is the genetic system of the chloroplast and the hypothesis that the chloroplast represents an evolved endosymbiont are discussed.

Radial mass analysis of unstained STEM images of molluscan hemocyanins

1990 ◽  
Vol 48 (3) ◽  
pp. 810-811
Author(s):  
M.G. Hamilton ◽  
T.T. Herskovits ◽  
J.S. Wall
Keyword(s):  
Image Analysis ◽  
Hollow Cylinder ◽  
Electron Micrographs ◽  
Side View ◽  
Mass Analysis ◽  
Mass Measurements ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies

The hemocyanins of molluscs are aggregates of a cylindrical decameric subparticle that assembles into di-, tri-, tetra-, penta-, and larger multi-decameric particles with masses that are multiples of the 4.4 Md decamer. Electron micrographs of these hemocyanins typically show the particles with two profiles: circular representing the cylinder viewed from the end and rectangular representing the side-view of the hollow cylinder.The model proposed by Mellema and Klug from image analysis of a didecameric hemocyanin with the two decamers facing one another with collar (closed) ends outward fits the appearance of side-views of the negatively-stained cylinders. These authors also suggested that there might be caps at the ends. In one of a series of transmission electron microscopic studies of molluscan hemocyanins, Siezen and Van Bruggen supported the Mellema-Klug model, but stated that they had never observed a cap component. With STEM we have tested the end cap hypothesis by direct mass measurements across the end-views of unstained particles.

Transmission electron microscopic study of antennal sensilla of the female black fly, Simulium arcticum (IIL-3; IIS-10.11) (Diptera: Simuliidae)

1990 ◽  
Vol 68 (7) ◽  
pp. 1443-1453 ◽  
Author(s):  
J. F. Sutcliffe ◽  
E. G. Kokko ◽  
J. L. Shipp
Keyword(s):  
Electron Micrographs ◽  
Host Location ◽  
Scanning Electron Micrographs ◽  
Antennal Sensilla ◽  
Electron Microscopic ◽  
Olfactory Sensilla ◽  
Transmission Electron Microscopic Study ◽  
Sensilla Trichodea ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

The innervation and internal ultrastructure of the antennal flagellar sensilla of female Simulium arcticum (cytotypes IIL-3 and IIS-10.11) are described from transmission electron micrographs. Two types of contact chemosensilla and at least four types of olfactory sensilla (sensilla trichodea, two or more types of sensilla basiconica, grooved pegs) were found. These correspond to sensillar types previously described from scanning electron micrographs of the antennae of these species. In addition, possible thermo- and hygro-receptive sensilla coeloconica are described from the antennal tip. The sensory complement of the simuliid antenna is compared with those of certain other dipterans, and possible roles of these sensilla in host location and other behaviours are discussed.

STUDIES ON THE FLAGELLA OF ALGAE: III. ELECTRON MICROGRAPHS OF CHLAMYDOMONAS MOEWUSII

1953 ◽  
Vol 31 (6) ◽  
pp. 711-717 ◽  
Author(s):  
R. A. Lewin ◽  
Josephine O. Meinhart
Keyword(s):  
Electron Microscopy ◽  
Hollow Cylinder ◽  
Mating Type ◽  
Electron Micrographs ◽  
Structural Changes ◽  
Agglutination Reaction ◽  
Wild Type ◽  
Structural Differences ◽  
Chlamydomonas Moewusii ◽  
Axial Cylinder

Each flagellum of Chlamydomonas moewusii appears to originate at a basal granule beneath the papilla. The intact flagellum is composed of:(a) a central axis, consisting of 9 – 11 dense fibrils, 450 Å wide, fused laterally to form a hollow cylinder;(b) a less dense component, possibly fluid, within the axial cylinder; and(c) a sheath of less dense material, surrounding the axial cylinder, and clearly delimited by a superficial membrane which is believed to be semipermeable. Mating-type specificity seems to reside in this component, since it is involved in the agglutination reaction which precedes copulation.The flagellum terminates in a mucro 0.3 – 0.5 μ long. There is no whiplash filament. Certain structural changes, due to disorganization, disruption, or disintegration of the flagellar components, are described and figured. Possible modes of action of the flagella in cell propulsion are briefly discussed in the light of flagellar structure as revealed by electron microscopy. No structural differences have been observed between the flagella of paralyzed mutants and of wild-type cells.

scholarly journals An electron microscopic and optical diffraction analysis of the structure of Limulus telson muscle thick filaments.

1982 ◽  
Vol 92 (2) ◽  
pp. 443-451 ◽  
Author(s):  
R W Kensler ◽  
R J Levine
Keyword(s):  
Electron Microscopy ◽  
Diffraction Analysis ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Thick Filaments ◽  
Diffraction Patterns ◽  
Cross Bridges

Long, thick filaments (greater than 4.0 micrometer) rapidly and gently isolated from fresh, unstimulated Limulus muscle by an improved procedure have been examined by electron microscopy and optical diffraction. Images of negatively stained filaments appear highly periodic with a well-preserved myosin cross-bridge array. Optical diffraction patterns of the electron micrographs show a wealth of detail and are consistent with a myosin helical repeat of 43.8 nm, similar to that observed by x-ray diffraction. Analysis of the optical diffraction patterns, in conjunction with the appearance in electron micrographs of the filaments, supports a model for the filament in which the myosin cross-bridges are arranged on a four-stranded helix, with 12 cross-bridges per turn or each helix, thus giving an axial repeat every third level of cross-bridges (43.8 nm).

Morphologic Changes of Rabbit Ovarian Follicles Following Copulation

1973 ◽  
Vol 31 ◽  
pp. 554-555
Author(s):  
David D. Cherney ◽  
Liberato J. A DiDio ◽  
Pietro Motta
Keyword(s):  
Electron Microscopy ◽  
Microscopic Study ◽  
Electron Micrographs ◽  
Electron Microscopic Study ◽  
Ovarian Follicles ◽  
Preovulatory Follicle ◽  
Electron Microscopic ◽  
Causal Factors ◽  
The Subject ◽  
Morphologic Changes

The interrelated processes enabling the ovum to be released from the mammalian ovary have been the subject of many investigations, which resulted in the advancement of several hypotheses; none, however, can as yet totally explain the morphophysiologic events leading to and responsible for ovulation.This investigation deals with a comprehensive light and electron microscopic study of the morphologic changes related to ovulation in the rabbit. Moreover, an attempt is made to establish a correlation between the modification of the follicle and perifollicular structures and their most likely causal factors.The morphology of the non-stimulated follicle is illustrated in Figure 1. Following copulation, follicles were removed at 2,4,6,8 and 10 hours, processed for electron microscopy, and comparable electron micrographs taken. As expected, the apex of the preovulatory follicle exhibited the most dramatic changes since it is the site where ovulation takes place.

The Elmiskop 51, A Transmission Electron-Microscope with Permanent Magnet Magnification System

1969 ◽  
Vol 27 ◽  
pp. 74-75
Author(s):  
K. Müller ◽  
E. Ruska ◽  
H. Neff
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Permanent Magnet ◽  
Electron Micrographs ◽  
Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Point To Point

For routine analyses in laboratories of variing specialities, where a large number of electron micrographs are to be obtained quickly, the Elmiskope 51 has been developed.It has an accelerating voltage of 50 kV and permits Electron microscopic magnifications in steps of 1250:1 to 12 500:1. With high-resolution photoemulsions a point to point resolution of 20 to 25 Å can be reached.

Autoradiographic Location of Protein Synthesized by Liver Slices

1967 ◽  
Vol 25 ◽  
pp. 140-141
Author(s):  
Charles A. Ashley ◽  
Theodore Peters
Keyword(s):  
Electron Micrographs ◽  
Osmium Tetroxide ◽  
Liver Slice ◽  
Adjacent Area ◽  
Electron Microscopic ◽  
Minimum Area ◽  
Secretory Pathways ◽  
Electron Microscopic Autoradiography ◽  
Direct Counting ◽  
Fasted Rats

The location, migration, and secretory pathways followed by proteins, newly synthesized by the liver, were determined by electron microscopic autoradiography. Small (3x4x0.5 mm) slices of liver from fasted rats were incubated for 2 minutes in medium (0.1 ml per slice)containing H3-4,5-L-leucine and then transferred to medium with unlabeled leucine for further incubation. Total incubation times were 2,4,10,25,40 and 75 minutes. Control slices were incubated in medium containing labeled leucine and puromycin. Slices were fixed in 4% formaldehyde (prepared from paraformaldehyde), post-fixed in osmium tetroxide and embedded on end in Epon. Autoradiographs were prepared using Ilford L-4 and Kodak NTE emulsions. Exposure times varied from 3 to 30 weeks. Parallel experiments were performed in which the total counts per minute per milligram of liver slice at each time were determined by standard direct counting techniques. Electron micrographs (magnification approximately 5,000 X) covering a minimum area of 2,000 μ2 of liver were taken of each specimen. The number of background grains in an adjacent area of equal size was determined for each specimen.

Electron Microscopic and Optical Diffraction Analyses of Crystalline Intranuclear Inclusions in Human Osteosarcoma Cells

1981 ◽  
Vol 39 ◽  
pp. 436-437
Author(s):  
Gonpachiro Yasuzumi
Keyword(s):  
Electron Micrographs ◽  
Periodic Structures ◽  
Bragg Reflection ◽  
Optical Diffraction ◽  
Intranuclear Inclusions ◽  
Osteosarcoma Cells ◽  
Electron Microscopic ◽  
Human Osteosarcoma ◽  
Human Osteosarcoma Cells ◽  
Diffraction Patterns

The fine structure of the crystalline intranuclear inclusions in the human osteosarcoma cells was studied by using a goniometer which tilted the specimen at angles of ±30° and ±40°. The results appear in the series of micrographs showing Fig. 1. At the point by the arrow, a helical structure is visible in two filaments. Optical diffrection patterns of selected areas of each negative electron micrograph film were taken by using a helium-neon laser as a source.A tentative model of the structure can be based on optical diffraction techniques applied to electron micrographs taken at different tilt angles. The diffraction pattern taken from image No. 0 in Fig. 1 is depicted in Fig. 2. Diffraction patterns from Nos. 3, 4 and 8 are shown in Figs. 3, 4 and 5. The contrast of some periodic structures can be eliminated in the image (extinction effect due to Bragg reflection of electron waves) by the interference of scattered waves from constituent elements. Hence it is rather important to interpret the electron micrographs and their optical diffraction patterns by considering the extinction effect of the image contrast.

Correlative Electron Microscopic and Cytofluorometric Study of Chromatin Conformation in Human Leukemia Cells

1980 ◽  
Vol 38 ◽  
pp. 734-735
Author(s):  
M. J. Ahearn ◽  
J. M. Trujillo
Keyword(s):  
Acridine Orange ◽  
Leukemic Cell ◽  
Correlated Data ◽  
Electron Microscopic Level ◽  
Human Leukemia ◽  
Chromatin Conformation ◽  
Cell Nuclei ◽  
Electron Microscopic ◽  
Quiescent Cells ◽  
Blast Count

In order to establish a sensitive probe to analyze and interpret the changes in chromatin conformation expressed in individual leukemic cell nuclei we have correlated data from a concomitant ultrastructural and cytofluorometric study on high blast count leukemic bone marrows utilizing the nuclear probe and metachromatic fluorochrome, acridine orange. At the electron microscopic level, the incorporation of this dye into “active euchro- matin” of morphologically identifiable leukemic blasts is visualized as Frenster’s1 electron dense reaction product (Fig 1). Cytofluorometrically, in the absence of RNA, acridine orange differentially stains double stranded DNA green (F530) and single stranded DNA red (F>600). Darzynkiewicz2 has demonstrated that the sensitivity of DNA in situ to denaturation is higher in quiescent cells than in actively cycling ones.

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