Der Dotterkern in jungen Oocyten von Noemacheilus barbatulus (L.) (Teleostei, Cobitidae) / The Yolk Nucleus in Young Oocytes of Neomacheilus barbatulus (L.) (Teleostei, Cobitidae)

1976 ◽  
Vol 31 (11-12) ◽  
pp. 761-762d ◽  
Author(s):  
Rüdiger Riehl
Keyword(s):  
Electron Microscopy ◽  
Nuclear Membrane ◽  
Ribonucleic Acid ◽  
Stage I ◽  
Freshwater Teleost ◽  
Nucleolar Material ◽  
Yolk Nucleus

Abstract The Yolk Nucleus in Young Oocytes of Neomacheilus barbatulus (L.) (Teleostei, Cobitidae) Yolk Nucleus, Oocytes, Electron Microscopy, Noemacheilus barbatulus The yolk nucleus in the young oocytes of the freshwater teleost Noemacheilus barbatulus (L.) was investigated by electron microscopy. Yolk nuclei are only found in stage I. They consist of nucleolar substance, mitochondria and partly of dictyosomes. The nucleolar material leaves the nucleus through the pores of the nuclear membrane and gets into the juxtanuclear cytoplasm. It mainly consists of ribonucleic acid. The yolk nuclei of Noemacheilus doesn’t have any relations to the formation of yolk.

Extrusion of Nuclear Material During Oogenesis in Blatta Orientalis

1962 ◽  
Vol s3-103 (62) ◽  
pp. 141-145
Author(s):  
R.A. R. GRESSON ◽  
L. T. THREADGOLD
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Close Association ◽  
Nuclear Material ◽  
Blatta Orientalis ◽  
Nucleolar Material

That nucleolar material is extruded to the cytoplasm of the young oocyte of Blatta orientalis is confirmed by means of electron microscopy. The nucleolus and nucleolar extrusions are shown to contain RNA. In addition to the nucleolar extrusions, vesicle-like structures originate in the nuclear membrane and from there pass into the cytoplasm where they become indistinguishable from elements of the endoplasmic reticulum. When the nucleolar extrusions reach the cytoplasm they increase in size, come into close association with a few mitochondria, and migrate towards the periphery of the cell. It is concluded that the emission of material from the nucleolus and the passage of vesicles from the nuclear membrane to the cytoplasm are necessary prerequisites for the process of vitellogenesis.

Prebiotic studies on the interaction of zirconia nanoparticles and ribose nucleotides and their role in chemical evolution

2021 ◽  
Vol 20 (2) ◽  
pp. 142-149
Author(s):  
Avnish Kumar Arora ◽  
Pankaj Kumar
Keyword(s):  
Electron Microscopy ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Chemical Evolution ◽  
Ribonucleic Acid ◽  
Zirconium Oxide ◽  
Origins Of Life ◽  
Neutral Ph ◽  
Interaction Studies

AbstractStudies on the interaction of biomolecules with inorganic compounds, mainly mineral surfaces, are of great concern in identifying their role in chemical evolution and origins of life. Metal oxides are the major constituents of earth and earth-like planets. Hence, studies on the interaction of biomolecules with these minerals are the point of concern for the study of the emergence of life on different planets. Zirconium oxide is one of the metal oxides present in earth's crust as it is a part of several types of rocks found in sandy areas such as beaches and riverbeds, e.g. pebbles of baddeleyite. Different metal oxides have been studied for their role in chemical evolution but no studies have been reported about the role of zirconium oxide in chemical evolution and origins of life. Therefore, studies were carried out on the interaction of ribonucleic acid constituents, 5′-CMP (cytidine monophosphate), 5′-UMP (uridine monophosphate), 5′-GMP (guanosine monophosphate) and 5′-AMP (adenosine monophosphate), with zirconium oxide. Synthesized zirconium oxide particles were characterized by using vibrating sample magnetometer, X-Ray Diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy. Zirconia particles were in the nanometre range, from 14 to 27 nm. The interaction of zirconium oxide with ribonucleic acid constituents was performed in the concentration range of 5 × 10−5–300 × 10−5 M. Interaction studies were carried out in three mediums; acidic (pH 4.0), neutral (pH 7.0) and basic (pH 9.0). At neutral pH, maximum interaction was observed. The interaction of zirconium oxide with 5′-UMP was 49.45% and with 5′-CMP 67.98%, while with others it was in between. Interaction studies were Langmurian in nature. Xm and KL values were calculated. Infrared spectral studies of ribonucleotides, metal oxide and ribonucleotide–metal oxide adducts were carried out to find out the interactive sites. It was observed that the nitrogen base and phosphate moiety of ribonucleotides interact with the positive charge surface of metal oxide. SEM was also carried out to study the adsorption. The results of the present study favour the important role of zirconium oxide in concentrating the organic molecules from their dilute aqueous solutions in primeval seas.

scholarly journals A Cellular Reaction to Antibody in Tissue Culture Studied with Electron Microscopy

1959 ◽  
Vol 5 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Harrison Latta
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Normal Serum ◽  
Butyl Methacrylate ◽  
Heart Cells ◽  
Plasma Clot ◽  
Outer Nuclear Membrane ◽  
Cell Components

The reaction of embryonic chick heart cells grown in tissue culture to specific guinea pig antiserum has been studied with electron microscopy. Heart fragments from chick embryos were cultured with a plasma clot. After being tested with antiserum or normal serum, they were fixed with buffered osmium tetroxide and embedded in butyl methacrylate before removal from the glass culture chamber. Thin cells found by phase microscopy to have reacted were sectioned in a plane parallel to the glass surface on which they had grown. The results confirm and extend observations made previously while the reactions were occurring. The plasma membrane, like that of the red cell, becomes disrupted or less resistant to trauma following the action of antiserum. The membranes of mitochondria and endoplasmic reticulum vesiculate and swell. Before nuclear shrinkage becomes prominent, the outer nuclear membrane separates over a large portion of the nuclear envelope and forms one or more large swollen blebs. Thus, the outer nuclear membrane shows a reactivity similar to endoplasmic reticulum. It is suggested that the various physical and chemical changes observed to follow the action of antibody and complement on fibroblasts may be explained by osmotic pressure differences between various cell components. Some basic similarities to the action of hemolytic agents on red cells are noted.

scholarly journals ELECTRON MICROSCOPY OF THE NUCLEAR MEMBRANE OF AMOEBA PROTEUS

1956 ◽  
Vol 2 (4) ◽  
pp. 445-448 ◽  
Author(s):  
Marie H. Greider ◽  
Wencel J. Kostir ◽  
Walter J. Frajola
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Nuclear Membrane ◽  
Outer Layer ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Cell Types ◽  
Amoeba Proteus ◽  
Nuclear Membranes ◽  
Thin Sectioning

An electron microscope study of the nuclear membrane of Amoeba proteus by thin sectioning techniques has revealed an ultrastructure in the outer layer of the membrane that is homologous to the pores and annuli observed in the nuclear membranes of many other cell types studied by these techniques. An inner honeycombed layer apparently unique to Amoeba proteus is also described.

scholarly journals The fine structure produced in cells by primary fixatives 2. Potassium dichromate

1965 ◽  
Vol s3-106 (73) ◽  
pp. 15-21
Author(s):  
JOHN R. BAKER
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Nuclear Membrane ◽  
Osmium Tetroxide ◽  
Potassium Dichromate ◽  
Potassium Dichromate Solution ◽  
Zymogen Granules ◽  
Mouse Pancreas

The exocrine cells of the mouse pancreas were fixed in potassium dichromate solution, embedded in araldite or other suitable medium, and examined by electron microscopy. Almost every part of these cells is seriously distorted or destroyed by this fixative. The ergastoplasm is generally unrecognizable, the mitochondria and zymogen granules are seldom visible, and no sign of the plasma membrane, microvilli, or Golgi apparatus is seen. The contents of the nucleus are profoundly rearranged. It is seen to contain a large, dark, irregularly shaped, finely granular object; the evidence suggests that this consists of coagulated histone. The sole constituent of the cell that is well fixed is the inner nuclear membrane. The destructive properties of potassium dichromate are much mitigated when it is mixed in suitable proportions with osmium tetroxide or formaldehyde.

Further observations on nucleolar tails in amphibian oocytes

1991 ◽  
Vol 99 (3) ◽  
pp. 515-521
Author(s):  
PEDRO LEÓN ◽  
JAMES KEZER ◽  
ERIC SCHABTACH
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Outer Surface ◽  
Light And Electron Microscopy ◽  
Nuclear Pores ◽  
Core Component ◽  
Amphibian Species ◽  
Attachment Structures ◽  
Convoluted Tubules

Large oocytes from some amphibian species possess beaded or unbeaded intranuclear tails that penetrate the extrachromosomal nucleoli through a distinct pit in their surface and attach to the central core component Here we show, using light and electron microscopy, that tails anchor nucleoli to the nuclear envelope through intricate attachment structures. These structures are composed of interconnected spherical masses containing highly convoluted tubules and associated extratubular proteins, directly directly in contact with the inner nuclear membrane. Fibers emerging from the nuclear pores seemingly hold the attachment complex in place. Beads on the nucleolar tails are formed by the accumulation of proteins on the outer surface of smooth tubules. The function of these intranuclear tubules is unknown

Memoirs: On the Relation of the Mitochondria and Golgi Apparatus to Yolk-Formation in the Egg-Cells of the Common Earthworm, Lumbricus Terrestris

1925 ◽  
Vol s2-69 (274) ◽  
pp. 291-316
Author(s):  
LESLIE A. HARVEY
Keyword(s):  
Golgi Apparatus ◽  
Nuclear Membrane ◽  
Lumbricus Terrestris ◽  
Yolk Formation ◽  
Central Mass ◽  
The Common ◽  
Yolk Nucleus ◽  
Earthworm Lumbricus

1. The yolk-nucleus is merely a mass of mitochondria. 2. The mitochondria arise as a cap of threads over the nucleus, and this cap grows in size and density, migrates away from the nuclear membrane and breaks up into its component mitochondrial threads. These threads become evenly spread throughout the cytoplasm of the cell. 3. The mitochondria are not clearly defined in the very young oogonia. 4. The Golgi apparatus consists of numbers of Golgi elements lying separate in the cytoplasm. There is never any attempt at concentration of these elements round one central mass. 5. The Golgi elements are probably little platelets or spheroids somewhat resembling blood corpuscles in shape. They are not rods. As fixed by Da Fano technique, each element is a little plate with a very lightly impregnating centre and a very heavily impregnating rim. 6. The Golgi elements may probably arise from the cytoplasm. 7. The nucleus contains two nucleoli; an early arising karyosome, homogeneous and solid in structure, and a plasmo some arising later This plasmosome is liquid in consistency and contains an argentophil core. The karyosome disappears before the oocyte is half grown, but the plasmosome remains in the nucleus while the egg remains in the ovary. 8. No visible nucleolar extrusions into the cytoplasm were observed. 9. Yolk probably arises from the cytoplasm; no direct metamorphosis of either mitochondria, Golgi apparatus, or nucleolus into yolk was observed.

scholarly journals The Primary Enveloped Virion of Herpes Simplex Virus 1: Its Role in Nuclear Egress

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
William W. Newcomb ◽  
Juan Fontana ◽  
Dennis C. Winkler ◽  
Naiqian Cheng ◽  
J. Bernard Heymann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Nuclear Membrane ◽  
Molecular Mechanisms ◽  
Weak Interactions ◽  
Nuclear Pore ◽  
Nuclear Egress ◽  
Cryo Electron Microscopy ◽  
Perinuclear Space ◽  
Infected Cells ◽  
Hsv 1

ABSTRACTMany viruses migrate between different cellular compartments for successive stages of assembly. The HSV-1 capsid assembles in the nucleus and then transfers into the cytoplasm. First, the capsid buds through the inner nuclear membrane, becoming coated with nuclear egress complex (NEC) protein. This yields a primary enveloped virion (PEV) whose envelope fuses with the outer nuclear membrane, releasing the capsid into the cytoplasm. We investigated the associated molecular mechanisms by isolating PEVs from US3-null-infected cells and imaging them by cryo-electron microscopy and tomography. (pUS3 is a viral protein kinase in whose absence PEVs accumulate in the perinuclear space.) Unlike mature extracellular virions, PEVs have very few glycoprotein spikes. PEVs are ~20% smaller than mature virions, and the little space available between the capsid and the NEC layer suggests that most tegument proteins are acquired later in the egress pathway. Previous studies have proposed that NEC is organized as hexamers in honeycomb arrays in PEVs, but we find arrays of heptameric rings in extracts from US3-null-infected cells. In a PEV, NEC contacts the capsid predominantly via the pUL17/pUL25 complexes which are located close to the capsid vertices. Finally, the NEC layer dissociates from the capsid as it leaves the nucleus, possibly in response to pUS3-mediated phosphorylation. Overall, nuclear egress emerges as a process driven by a program of multiple weak interactions.IMPORTANCEOn its maturation pathway, the newly formed HSV-1 nucleocapsid must traverse the nuclear envelope, while respecting the integrity of that barrier. Nucleocapsids (125 nm in diameter) are too large to pass through the nuclear pore complexes that conduct most nucleocytoplasmic traffic. It is now widely accepted that the process involves envelopment/de-envelopment of a key intermediate—the primary enveloped virion. In wild-type infections, PEVs are short-lived, which has impeded study. Using a mutant that accumulates PEVs in the perinuclear space, we were able to isolate PEVs in sufficient quantity for structural analysis by cryo-electron microscopy and tomography. The findings not only elucidate the maturation pathway of an important human pathogen but also have implications for cellular processes that involve the trafficking of large macromolecular complexes.

scholarly journals Visualization of the Nuclear Lamina in Mouse Anterior Pituitary Cells and Immunocytochemical Detection of Lamin A/C by Quick-freeze Freeze-substitution Electron Microscopy

2005 ◽  
Vol 53 (4) ◽  
pp. 497-507 ◽  
Author(s):  
Takao Senda ◽  
Akiko Iizuka-Kogo ◽  
Atsushi Shimomura
Keyword(s):  
Electron Microscopy ◽  
Nuclear Membrane ◽  
Anterior Pituitary ◽  
Freeze Substitution ◽  
Nuclear Lamina ◽  
Immunogold Electron Microscopy ◽  
Lamin A ◽  
Pituitary Cells ◽  
Inner Nuclear Membrane ◽  
Anterior Pituitary Cells

We examined the nuclear lamina in the quickly frozen anterior pituitary cells by electron microscopic techniques combined with freeze substitution, deep etching, and immunocytochemistry and compared it with that in the chemically fixed cells. By quick-freeze freeze-substitution electron microscopy, an electron-lucent layer, as thick as 20 nm, was revealed just inside the inner nuclear membrane, whereas in the conventionally glutaraldehyde-fixed cells the layer was not seen. By quick-freeze deep-etch electron microscopy, we could not distinguish definitively the layer corresponding to the nuclear lamina in either fresh unfixed or glutaraldehyde-fixed cells. Immunofluorescence microscopy showed that lamin A/C in the nucleus was detected in the acetone-fixed cells and briefly in paraformaldehyde-fixed cells but not in the cells with prolonged paraformaldehyde fixation. Nuclear localization of lamin A/C was revealed by immunogold electron microscopy also in the quickly frozen and freeze-substituted cells, but not in the paraformaldehyde-fixed cells. Lamin A/C was localized mainly in the peripheral nucleoplasm within 60 nm from the inner nuclear membrane, which corresponded to the nuclear lamina. These results suggest that the nuclear lamina can be preserved both ultrastructurally and immunocytochemically by quick-freezing fixation, rather than by conventional chemical fixation.

Ultrastructural studies on mitosis in Trypanosoma danilewskyi (Mastigophora: Zoomastigophorea)

1984 ◽  
Vol 62 (6) ◽  
pp. 1167-1171 ◽  
Author(s):  
W. Brockley Paterson ◽  
Patrick T. K. Woo
Keyword(s):  
Nuclear Membrane ◽  
Polar Regions ◽  
Kinetoplast Dna ◽  
Inner Nuclear Membrane ◽  
Daughter Cells ◽  
Ultrastructural Studies ◽  
Nuclear Membranes ◽  
Transmission Electron ◽  
Nucleolar Material ◽  
Spindle Microtubules

Mitosis of Trypanosoma danilewskyi was studied using transmission electron microscopy. The basal body replicates prior to the kinetoplast. Nuclear division is coincident with the first part of cytokinesis. The kinetoplast DNA appears to disaggregate and then recondense as two strands. In the early phase of mitosis the chromatin and nucleolar material also disaggregate, but the nuclear membranes persist throughout mitosis. Electron-dense plaques, possibly kinetochores, were observed on the spindle microtubules in the polar regions of dividing nuclei. Additional electron-dense material was observed on the inner nuclear membranes adjacent to the plaques and microtubules but without connection to these latter structures. Daughter nuclei migrate but remain temporarily connected by a bridge composed of spindle microtubules enclosed by both nuclear membranes. During the final stages of karyokinesis the inner nuclear membrane reorganizes to exclude the microtubules of the bridge from the nucleoplasm. The nucleolus and chromatin reform, with the nucleolus being temporarily connected to the inner nuclear membrane by a chromatin strand. Cytokinesis is accomplished by transverse symmetrogenic fission, and the daughter cells are temporarily connected by a cytoplasmic isthmus.

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