scholarly journals Widespread Transcription in an Amphibian Oocyte Relates to Its Reprogramming Activity on Transplanted Somatic Nuclei

2012 ◽  
Vol 21 (2) ◽  
pp. 181-190 ◽  
Author(s):  
Ilenia Simeoni ◽  
Mike J. Gilchrist ◽  
Nigel Garrett ◽  
Javier Armisen ◽  
John B. Gurdon
Keyword(s):  
Amphibian Oocyte

Pattern of Incorporation of [3H]Uridine into RNA of Amphibian Oocyte Nucleoli

1967 ◽  
Vol 2 (2) ◽  
pp. 145-150
Author(s):  
H. C. MACGREGOR
Keyword(s):  
Nuclear Envelope ◽  
Incubation Time ◽  
Core Material ◽  
Distinct Component ◽  
Thin Sections ◽  
The Core ◽  
Amphibian Oocyte ◽  
Nucleolar Rna ◽  
Silver Grains

Amphibian oocytes were incubated in vitro in the presence of [3H]uridine, and autoradiographs were made of nucleoli isolated from these oocytes and of sections of oocytes. After incubations of 2 h or less the nucleoli of oocytes larger than 0.6 mm diameter are asymmetrically labelled. With longer incubations nucleoli from oocytes of 0.6 to 1.1 mm diameter become more uniformly labelled. Those of oocytes larger than 1.2 mm diameter remain asymmetrically labelled whatever the incubation time. Autoradiographs of 1-µ sections through oocytes larger than 0.6 mm diameter show, after short incubations, asymmetrically labelled nucleoli. In these autoradiographs silver grains are concentrated over a distinct component of each nucleolus which is eccentrically placed towards the nuclear envelope. Thin sections of oocytes show nucleoli consisting of core and cortex. The core material is always concentrated into the half of the nucleolus which lies nearer the nuclear envelope. Autoradiographs of separated nucleolar cores and cortices from oocytes larger than 0.6 mm diameter show, after short incubations, silver grains over cores but not over cortices. Similar autoradiographs prepared from oocytes of 0.6 to 1.1 mm diameter, after longer incubations, show grains over cores and cortices. These results appear to indicate that nucleolar RNA is synthesized in the nucleolar core, in association with the nucleolar DNA, and is thence transferred to the cortex where it is built into ribonucleoprotein particles. Initial asymmetrical labelling is a consequence of the eccentric location of the nucleolar core. The nucleoli of oocytes smaller than 0.6 mm diameter always label symmetrically; such nucleoli consist entirely of core material. It is suggested that the nucleoli of oocytes larger than 1.2 mm diameter always label asymmetrically because transfer of RNA from core to cortex proceeds more slowly than in smaller oocytes.

HSP70 Is Involved in the Control of Chromosomal Transcription in the Amphibian Oocyte

2000 ◽  
Vol 260 (2) ◽  
pp. 222-232 ◽  
Author(s):  
Charlotte Delelis-F. Corporeau ◽  
Nicole Angelier ◽  
May Penrad-Mobayed
Keyword(s):  
Amphibian Oocyte

scholarly journals The sphere organelle contains small nuclear ribonucleoproteins

1989 ◽  
Vol 86 (17) ◽  
pp. 6635-6639 ◽  
Author(s):  
J G Gall ◽  
H G Callan
Keyword(s):  
Immunofluorescence Microscopy ◽  
Lampbrush Chromosome ◽  
Specific Chromosome ◽  
Animal Kingdom ◽  
Amphibian Oocyte ◽  
Small Nuclear Ribonucleoproteins ◽  
The Way

We show by immunofluorescence microscopy of amphibian oocyte nuclei that small nuclear ribonucleoproteins (snRNPs) occur in lampbrush chromosome loops, in a few dozen extrachromosomal organelles previously described as "spheres," and in thousands of smaller granules. Spheres are variable in size (up to approximately 20 microns in diameter in the newt Notophthalmus and approximately 10 microns in the frog Xenopus) and are easily distinguishable from nucleoli by morphology and composition. Spheres occur both free in the nucleoplasm and attached to specific chromosome loci, the sphere organizers. Oocyte nuclei of a cricket and a spider contain essentially similar organelles, suggesting that spheres may be common throughout the animal kingdom. We suggest that spheres play a role in the assembly of snRNP complexes for the nucleus comparable to the way that nucleoli assemble ribosomal RNP complexes for the cytoplasm.

scholarly journals Amphibian oocyte nuclei expressing lamin A with the progeria mutation E145K exhibit an increased elastic modulus

Nucleus ◽  
2011 ◽  
Vol 2 (4) ◽  
pp. 310-319 ◽  
Author(s):  
Anna Kaufmann ◽  
Fabian Heinemann ◽  
Manfred Radmacher ◽  
Reimer Stick
Keyword(s):  
Elastic Modulus ◽  
Lamin A ◽  
Amphibian Oocyte

scholarly journals THE PERMEABILITY OF THE AMPHIBIAN OOCYTE NUCLEUS, IN SITU

1972 ◽  
Vol 54 (3) ◽  
pp. 609-625 ◽  
Author(s):  
Samuel B. Horowitz
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Sucrose Concentration ◽  
Short Circuit ◽  
Pure Water ◽  
Oocyte Nucleus ◽  
Bathing Solution ◽  
Cytoplasmic Inclusions ◽  
Amphibian Oocyte ◽  
Water As Solvent

Ultralow temperature radioautography, suitable for the quantitative localization of diffusible solutes, was used to study the permeability of the nuclear envelope in the intact amphibian oocyte Sucrose-3H solutions were injected into mature oocytes, in volumes of 0 016–0 14% of that of the cell, and the subsequent movement of the solute was recorded. The resultant radioautographs show diffusion gradients in the cytoplasm and nucleus, and concentration gradients across the nuclear envelope Analysis of these gradients discloses that the nuclear envelope is as permeable as a comparable structure composed of cytoplasm, and is about 108 times more permeable than the oocyte plasma membrane The diffusion coefficient of sucrose in cytoplasm is 2 x 10-6 cm2/sec, or about one-third its diffusivity in pure water. This reduction can probably be accounted for by an effective lengthening of the diffusional path because of obstruction by cytoplasmic inclusions. The nuclear: cytoplasmic sucrose concentration ratio at diffusional equilibrium is about 3 05, or 1.6 times as great as expected from the water content of the two compartments This asymmetry is attributed to an unavailability of 36% of the cytoplasmic water as solvent Finally, sucrose entry into oocytes from a bathing solution was monitored by whole cell analysis and radioautography. These and the microinjection results are consistent with a model in which sucrose entry into the cell is entirely limited by the permeability of the plasma membrane. The results are inconsistent with cell models that hypothesize a short-circuit transport route from the extracellular compartment to the nucleus, and with models in which cytoplasmic diffusion is viewed as limiting the rate of solute permeation.

scholarly journals Epigenetic marks in somatic chromatin are remodelled to resemble pluripotent nuclei by amphibian oocyte extracts

Epigenetics ◽  
2009 ◽  
Vol 4 (3) ◽  
pp. 194-202 ◽  
Author(s):  
Yuhong Bian ◽  
Ramiro Alberio ◽  
Cinzia Allegrucci ◽  
Keith H. Campbell ◽  
Andrew D. Johnson
Keyword(s):  
Epigenetic Marks ◽  
Amphibian Oocyte
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