An Ultrastructural and Radio-Autographic Study of the Effect Of Ethidium Bromide on the Interphase Nucleus of Meristematic Plant Cells

1973 ◽  
Vol 13 (1) ◽  
pp. 97-119
Author(s):  
A. LORD ◽  
J. G. LAFONTAINE
Keyword(s):  
Ethidium Bromide ◽  
Raphanus Sativus ◽  
Interphase Nucleus ◽  
Light And Electron Microscopy ◽  
Plant Cells ◽  
Small Bodies ◽  
Normal Cells ◽  
Nuclear Structures ◽  
Degree Of Condensation ◽  
Intermediate Dose

In the present work the effects of an intermediate dose (20µg/ml) of ethidium bromide on nuclear structures of meristematic plant cells (Raphanus sativus) have been studied under both light and electron microscopy. Radioautography was also exploited to assess the action of this drug on the incorporation activity of nucleic acid precursors. After a 30-min treatment with ethidium bromide, no noticeable ultrastructural modifications are detected but the incorporation of both thymidine and uridine is already markedly impaired. As treatment is extended to 1 h, the numerous light lacunae characterizing the fibrillar nucleolar zones in normal cells transform into elongated areas which are often found to extend to the surface of this organelle and are continuous with perinucleolar chromatin masses. After 2 h, many small bodies consisting of granular material appear in the nucleoplasm. The nucleolus gradually loses most of its granular component and, eventually, becomes predominantly fibrillar in texture; in many cells it breaks up into a number of irregular masses. Throughout various stages of the experiment, certain cells show small spherical nucleoli characterized by the presence on their surface of one or two conspicuous reticulate masses which are heavily labelled with thymidine and, consequently, consist mostly of chromatin. In view of the fact that ethidium bromide has been observed in this study to induce a certain degree of condensation of chromatin within the nuclear cavity, it is surmised that this drug also brings about migration of intranucleolar DNA to the surface of this organelle.

An Ultrastructural and Radio-Autographic Study of the Evolution of the Interphase Nucleus in Plant Meristematic Cells (Allium Porrum)

1974 ◽  
Vol 14 (2) ◽  
pp. 263-287
Author(s):  
J. G. LAFONTAINE ◽  
A. LORD
Keyword(s):  
Interphase Nucleus ◽  
Structural Changes ◽  
Tritiated Thymidine ◽  
Light And Electron Microscopy ◽  
Allium Porrum ◽  
Meristematic Cells ◽  
Fibrillar Material ◽  
Nuclear Structures ◽  
S Period ◽  
Dense Chromatin

Radioautography under both light and electron microscopy was exploited to investigate the structural changes of the chromatin reticulum which characterizes the interphase nucleus of a number of plants. Allium porrum meristematic plant cells were used for this purpose. In this species, the telophase chromosomes uncoil into dense strands which, during the G1 period, gradually give rise to a coarse reticulum. There then follows an extensive unravelling of portions of these strands, and high-resolution radioautography reveals that labelling with tritiated thymidine predominantly occurs over zones of the nucleus consisting of diffuse fine fibrillar material. As the S-period progresses, a chromatin reticulum reappears throughout the nuclear cavity, the tortuous strands being approximately 0.25 µm in diameter. Most of the radioautographic grains still remain over the light nucleoplasmic areas but a number of these are now located on the outermost portion of the dense chromatin profiles. By the end of the S-period, the chromatin strands are slightly thicker (ca. 0.3 µm) and form a looser reticulum. Labelling has decreased noticeably in nuclei of that period, the radioautographic grains being grouped into clusters resting over more or less spherical regions of the chromatin reticulum. Judging from their localization at the surface of the nucleolus or close to the nuclear envelope, these structures correspond to chromocentres. The additional interesting finding that such nuclear structures appear much less compactly organized strongly suggests that chromocentres undergo important conformational modifications during duplication of their DNA.

Fine Structure of the Eye of a Nudibranch Mollusc, Hermissenda Crassicornis

1967 ◽  
Vol 2 (3) ◽  
pp. 349-358
Author(s):  
R. M. EAKIN ◽  
JANE A. WESTFALL ◽  
M. J. DENNIS
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Optic Nerve ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Sensory Cells ◽  
Nerve Fibres ◽  
Supporting Cells ◽  
Small Bodies ◽  
Receptor Cells

The eye of a nudibranch, Hermissenda crassicornis, was studied by light and electron microscopy. Three kinds of cells were observed: large sensory cells, each bearing at one end an array of microvilli (rhabdomere) and at the other end an axon which leaves the eye by the optic nerve; large pigmented supporting cells; and small epithelial cells, mostly corneal. There are five sensory cells, and the same number of nerve fibres in the optic nerve. The receptor cells contain an abundance of small vesicles, 600-800 Å in diameter. The lens is a spheroidal mass of osmiophilic, finely granular material. A basal lamina and a capsule of connective tissue enclose the eye. In some animals the eye is ‘infected’ with very small bodies, 4-5 µ in diameter, thought to be symbionts.

scholarly journals Subcellular Microanatomy by 3D Deconvolution Brightfield Microscopy: Method and Analysis Using Human Chromatin in the Interphase Nucleus

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Paul Joseph Tadrous
Keyword(s):  
Plasma Cell ◽  
Interphase Nucleus ◽  
Light And Electron Microscopy ◽  
3D Structure ◽  
Cell Types ◽  
Structural Basis ◽  
3 Dimensional ◽  
First Results ◽  
Brightfield Microscopy ◽  
Subcellular Resolution

Anatomy has advanced using 3-dimensional (3D) studies at macroscopic (e.g., dissection, injection moulding of vessels, radiology) and microscopic (e.g., serial section reconstruction with light and electron microscopy) levels. This paper presents the first results in human cells of a new method of subcellular 3D brightfield microscopy. Unlike traditional 3D deconvolution and confocal techniques, this method is suitable for general application to brightfield microscopy. Unlike brightfield serial sectioning it has subcellular resolution. Results are presented of the 3D structure of chromatin in the interphase nucleus of two human cell types, hepatocyte and plasma cell. I show how the freedom to examine these structures in 3D allows greater morphological discrimination between and within cell types and the 3D structural basis for the classical “clock-face” motif of the plasma cell nucleus is revealed. Potential for further applications discussed.

Effect of ethidium bromide on the fine structure of the nucleolus in plant cells

1972 ◽  
Vol 39 (1-2) ◽  
pp. 163-172 ◽  
Author(s):  
M.C. Risueño ◽  
M.E. Fernández-gómez ◽  
C. de la Torre ◽  
G. Giménez-Martín
Keyword(s):  
Fine Structure ◽  
Ethidium Bromide ◽  
Plant Cells

scholarly journals Space botany in Lithuania. I. Root gravisensing system formation during satellite “Bion-10” flight

2013 ◽  
Vol 19 (2) ◽  
pp. 129-138 ◽  
Author(s):  
Danguolė Švegždienė ◽  
Danguolė Raklevičienė ◽  
Dalia Koryznienė
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Plant Cells ◽  
Lepidium Sativum ◽  
Garden Cress ◽  
Cell Region ◽  
System Formation ◽  
Cell Position ◽  
Distal Cell ◽  
Lepidium Sativum L

Abstract Švegždienė D., Raklevičienė D., Koryzienė D., 2013: Space botany in Lithuania. I. Root gravisensing system formation during satellite “Bion-10” flight [Kosminė botanika Lietuvoje. I. Gravitaciją juntančių šaknų ląstelių formavimasis palydovo „Bion-10“ skrydžio metu]. - Bot. Lith., 19(2): 129-138. The paper deals with the results of space experiment, which was carried out on an original automatically operating centrifuge „Neris-5“ on board of the satellite „Bion-10“ in 1993. The peculiarities of gravisensing system formation in roots of garden cress (Lepidium sativum L.) seedlings grown in microgravity under simulated and natural gravity of 1g in space and on the ground, respectively, are presented. Quantitative study on the growth of root columella cells (statocytes), the state of their intracellular components, and the location of amyloplasts was performed by light and electron microscopy. The growth of statocytes in microgravity and under 1g in space did not differ significantly though the location of amyloplasts experienced significant changes: it depended on the gravity and cell position in columella. Instead of the concentration of amyloplasts at the distal cell region of roots grown under 1g, most plastids in microgravity-grown roots were accumulated at the centre of statocytes. The obtained data on the formation and state of intercellular plastids confirm the supposition that the environment of microgravity alters the metabolism of plant cells; however, its alterations are not fateful for the formation of gravisensing cells and for the growth of the whole root.

Nuclear division in the trophic stages of Iodamoeba bütschlii (Prowazek, 1912) Dobell, 1919

Parasitology ◽  
1959 ◽  
Vol 49 (3-4) ◽  
pp. 543-551 ◽  
Author(s):  
Chia-Tung Pan
Keyword(s):  
Nuclear Membrane ◽  
Interphase Nucleus ◽  
Daughter Cell ◽  
Nuclear Division ◽  
Early Prophase ◽  
Nuclear Morphology ◽  
Type I ◽  
Interphase Nuclei ◽  
Nuclear Structures

1. Study of the nuclear morphology of a large number of haematoxylin-stained specimens of Iodamoeba bütschlii has permitted description of the process of nuclear division in this organism.2. The interphase nuclei of the trophozoites were classified into four types (types I to IV) depending on the distribution of the periendosomal granules. The development of the four types of interphase nuclei appears to follow the process of nuclear division.3. During the early prophase stages the periendosomal granules are incorporated into the endosome. More than twenty small granules are formed from the organizing endosome.4. In late metaphase stages more than ten, and probably twelve, granules can usually be counted per set of the daughter chromosomes.5. The centrodesmus may extend beyond the nuclear boundary during the anaphase stages, while the nuclear membrane appears intact.6. The periendosomal granules reappear by the end of telophase stages when the two daughter nuclei are nearly completely separated.7. In the freshly separated daughter cell the nucleus may still retain the trailing tail and appear tadpole-shaped, but the periendosomal granules are usually arranged like those in the type I interphase nucleus.8. The validity of the genus Iodamoeba is re-emphasized on the basis of the characteristic nuclear structures and the unique process of nuclear division as here described for I. bütschlii.

Cytokinesis at prophase in plant cells treated with ethidium bromide

1970 ◽  
Vol 62 (2-3) ◽  
pp. 464-467 ◽  
Author(s):  
A. González-Fernández ◽  
G. Giménez-Martín ◽  
J.E. López-Sáez
Keyword(s):  
Ethidium Bromide ◽  
Plant Cells

An ultrastructural and radioautographic study of the chromocentric interphase nucleus in plant meristematic cells (Raphanus sativus)

1976 ◽  
Vol 21 (1) ◽  
pp. 193-207
Author(s):  
A. Lord ◽  
J.G. Lafontaine
Keyword(s):  
High Resolution ◽  
Raphanus Sativus ◽  
Interphase Nucleus ◽  
Mitotic Chromosomes ◽  
Structural Differentiation ◽  
Interphase Nuclei ◽  
Meristematic Cells ◽  
Late Telophase ◽  
S Period ◽  
Chromosome Segments

In Raphanus sativus, the mitotic chromosomes are quite short and, on reaching the cell poles, soon undergo extensive unravelling. By late telophase and early interphase, only a few chromosome segments, believed to correspond to the centromeric regions, are still visible in the form of chromocentres closely associated with the nuclear envelope. Although interphase nuclei show little internal structural differentiation, high-resolution radioautography has permitted us to establish which of them have reached the early, mid and late S periods. In early S nuclei, only the nucleolus and the euchromatin which pervades the nuclear cavity become labelled. By the mid S-period, the diffuse chromatin and nucleolus incorporate less thymidine and DNA synthesis is initiated within the peripheral chromocentres. Subsequently, the radioautographic grains become restricted to the chromocentres. The finding that certain late S nuclei exhibit loosely organized chromocentres strongly suggests that these heterochromatic chromosome segments undergo important conformational modifications during DNA replication. Finally, the presence of radioautographic grains over the lacunar regions of the nucleolus in early and mid S nuclei demonstrates that intranucleolar DNA replicates during the earlier portion of the S-period.

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