scholarly journals Cajal Bodies, Nucleoli, and Speckles in the Xenopus Oocyte Nucleus Have a Low-Density, Sponge-like Structure

2005 ◽  
Vol 16 (1) ◽  
pp. 202-211 ◽  
Author(s):  
Korie E. Handwerger ◽  
Jason A. Cordero ◽  
Joseph G. Gall
Keyword(s):  
Xenopus Oocyte ◽  
Aqueous Media ◽  
Germinal Vesicle ◽  
Physical Structure ◽  
Cajal Bodies ◽  
Oocyte Nucleus ◽  
Refractive Indices ◽  
Low Density ◽  
Penetration Data ◽  
Fibrillar Region

Nuclear organelles, unlike many cytoplasmic organelles, lack investing membranes and are thus in direct contact with the surrounding nucleoplasm. Because the properties of the nucleoplasm and nuclear organelles influence the exchange of molecules from one compartment to another, it is important to understand their physical structure. We studied the density of the nucleoplasm and the density and permeability of nucleoli, Cajal bodies (CBs), and speckles in the Xenopus oocyte nucleus or germinal vesicle (GV). Refractive indices were measured by interferometry within intact GVs isolated in oil. The refractive indices were used to estimate protein concentrations for nucleoplasm (0.106 g/cm3), CBs (0.136 g/cm3), speckles (0.162 g/cm3), and the dense fibrillar region of nucleoli (0.215 g/cm3). We determined similar protein concentrations for nuclear organelles isolated in aqueous media, where they are no longer surrounded by nucleoplasm. To examine the permeability of nuclear organelles, we injected fluorescent dextrans of various molecular masses (3–2000 kDa) into the cytoplasm or directly into the GV and measured the extent to which they penetrated the organelles. Together, the interferometry and dextran penetration data show that organelles in the Xenopus GV have a low-density, sponge-like structure that provides access to macromolecules from the nucleoplasm.

Heat shock induces mini-Cajal bodies in the Xenopus germinal vesicle

2002 ◽  
Vol 115 (10) ◽  
pp. 2011-2020 ◽  
Author(s):  
Korie E. Handwerger ◽  
Zheng'an Wu ◽  
Christine Murphy ◽  
Joseph G. Gall
Keyword(s):  
Heat Shock ◽  
Germinal Vesicle ◽  
Model System ◽  
Cajal Body ◽  
Self Organization ◽  
Cajal Bodies ◽  
Oocyte Nucleus ◽  
Evolutionarily Conserved ◽  
And Behavior ◽  
Heat Shock Induction

Cajal bodies are evolutionarily conserved nuclear organelles that are believed to play a central role in assembly of RNA transcription and processing complexes. Although knowledge of Cajal body composition and behavior has greatly expanded in recent years, little is known about the molecules and mechanisms that lead to the formation of these organelles in the nucleus. The Xenopus oocyte nucleus or germinal vesicle is an excellent model system for the study of Cajal bodies, because it is easy to manipulate and it contains 50-100 Cajal bodies with diameters up to 10 μm. In this study we show that numerous mini-Cajal bodies (less than 2 μm in diameter) form in the germinal vesicle after oocytes recover from heat shock. The mechanism for heat shock induction of mini-Cajal bodies is independent of U7 snRNA and does not require transcription or import of newly translated proteins from the cytoplasm. We suggest that Cajal bodies originate by self-organization of preformed components, preferentially on the surface of B-snurposomes.

TAFII70 protein in Cajal bodies of the amphibian germinal vesicle

Genome ◽  
2001 ◽  
Vol 44 (6) ◽  
pp. 1100-1103 ◽  
Author(s):  
Stefania Bucci ◽  
Letizia Giani ◽  
Giorgio Mancino ◽  
Mario Pellegrino ◽  
Matilde Ragghianti
Keyword(s):  
Monoclonal Antibody ◽  
Germinal Vesicle ◽  
Tata Binding Protein ◽  
Cajal Body ◽  
Cajal Bodies ◽  
Oocyte Nucleus ◽  
Lampbrush Chromosomes ◽  
Rna Transcription ◽  
Associated Factor ◽  
Oocyte Cytoplasm

The localization of the TATA-binding protein (TBP) associated factor II70 (TAFII70) in the germinal vesicle (GV) of newt oocytes was investigated. In spreads of GV content, anti-hTAFII70 monoclonal antibody (mAb) stained Cajal bodies (CBs) that were either attached to specific sites on the lampbrush chromosomes or free in the nucleoplasm. To confirm this localization the PwTAFII70 cDNA was cloned and myc-tagged transcripts injected into the oocyte cytoplasm. Newly translated PwTAFII70 protein was detected a few hours later in the Cajal bodies. These data support the hypothesis that Cajal bodies are the assembly sites of the transcription machinery of the oocyte nucleus. TAFII70 protein can play a role in lampbrush transcription; alternatively TAFII70 can be considered a component in the subset of TFIID complexes that do not function during oogenesis, but are accumulated in the oocyte for later use during early development.Key words: TAFII70, Cajal body, lampbrush chromosomes, RNA transcription and processing, newts, Pleurodeles.

scholarly journals Assembly of the Nuclear Transcription and Processing Machinery: Cajal Bodies (Coiled Bodies) and Transcriptosomes

1999 ◽  
Vol 10 (12) ◽  
pp. 4385-4402 ◽  
Author(s):  
Joseph G. Gall ◽  
Michel Bellini ◽  
Zheng’an Wu ◽  
Christine Murphy
Keyword(s):  
Germinal Vesicle ◽  
Cajal Bodies ◽  
Oocyte Nucleus ◽  
Electron Microscopic ◽  
Pol Ii ◽  
Processing Machinery ◽  
Small Nuclear Ribonucleoprotein ◽  
Coiled Bodies ◽  
Pol I ◽  
Pol Iii

We have examined the distribution of RNA transcription and processing factors in the amphibian oocyte nucleus or germinal vesicle. RNA polymerase I (pol I), pol II, and pol III occur in the Cajal bodies (coiled bodies) along with various components required for transcription and processing of the three classes of nuclear transcripts: mRNA, rRNA, and pol III transcripts. Among these components are transcription factor IIF (TFIIF), TFIIS, splicing factors, the U7 small nuclear ribonucleoprotein particle, the stem–loop binding protein, SR proteins, cleavage and polyadenylation factors, small nucleolar RNAs, nucleolar proteins that are probably involved in pre-rRNA processing, and TFIIIA. Earlier studies and data presented here show that several of these components are first targeted to Cajal bodies when injected into the oocyte and only subsequently appear in the chromosomes or nucleoli, where transcription itself occurs. We suggest that pol I, pol II, and pol III transcription and processing components are preassembled in Cajal bodies before transport to the chromosomes and nucleoli. Most components of the pol II transcription and processing pathway that occur in Cajal bodies are also found in the many hundreds of B-snurposomes in the germinal vesicle. Electron microscopic images show that B-snurposomes consist primarily, if not exclusively, of 20- to 30-nm particles, which closely resemble the interchromatin granules described from sections of somatic nuclei. We suggest the name pol II transcriptosome for these particles to emphasize their content of factors involved in synthesis and processing of mRNA transcripts. We present a model in which pol I, pol II, and pol III transcriptosomes are assembled in the Cajal bodies before export to the nucleolus (pol I), to the B-snurposomes and eventually to the chromosomes (pol II), and directly to the chromosomes (pol III). The key feature of this model is the preassembly of the transcription and processing machinery into unitary particles. An analogy can be made between ribosomes and transcriptosomes, ribosomes being unitary particles involved in translation and transcriptosomes being unitary particles for transcription and processing of RNA.

scholarly journals Conformation and Physical Structure of Tropoelastin from Human Vascular Cells: Influence of Cells Lipid Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Valerie Samouillan ◽  
Jany Dandurand ◽  
Laura Nasarre ◽  
Lina Badimon ◽  
Colette Lacabanne ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Smooth Muscle ◽  
Glass Transition ◽  
Absorption Band ◽  
Vascular Smooth Muscle Cells ◽  
Physical Structure ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Scanning Calorimetry ◽  
Water Affinity

Aggregated low density lipoproteins (agLDL) contribute to massive intracellular cholesteryl ester (CE) accumulation in human vascular smooth muscle cells (VSMC). Our aim was to determine the conformational and physical structure of agLDL and elastic material produced either by control human VSMC or by agLDL-loaded human VSMC (agLDL-VSMC). At the conformational level scanned by FTIR spectroscopy, a new undefined, probably non-H-bonded, structure for tropoelastin produced by agLDL-VSMC is revealed. By differential scanning calorimetry, a decrease of water affinity and a drop of the glass transition associated with aggregated tropoelastin (from 200°C to 159°C) in the supernatant from agLDL VSMC are evidenced. This second phenomenon is due to an interaction between agLDL and tropoelastin as detected by the weak specific FTIR absorption band of agLDL in supernatant from agLDL-loaded VSMC.

Modeling the Physical Structure of the Low‐Density Pre‐Protostellar Core Lynds 1498

2005 ◽  
Vol 632 (2) ◽  
pp. 982-1000 ◽  
Author(s):  
Yancy L. Shirley ◽  
Miranda K. Nordhaus ◽  
Jana M. Grcevich ◽  
Neal J. Evans II ◽  
Jonathan M. C. Rawlings ◽  
...  
Keyword(s):  
Physical Structure ◽  
Low Density

scholarly journals Reorganization of actin filaments by ADF/cofilin is involved in formation of microtubule structures during Xenopus oocyte maturation

2015 ◽  
Vol 26 (24) ◽  
pp. 4387-4400 ◽  
Author(s):  
Yuka Yamagishi ◽  
Hiroshi Abe
Keyword(s):  
Oocyte Maturation ◽  
Actin Filament ◽  
Actin Filaments ◽  
Xenopus Oocyte ◽  
Germinal Vesicle ◽  
Meiotic Spindle ◽  
Base Region ◽  
Microtubule Organizing Center ◽  
Cytoplasmic Actin ◽  
Organizing Center

We examined the reorganization of actin filaments and microtubules during Xenopus oocyte maturation. Surrounding the germinal vesicle (GV) in immature oocytes, the cytoplasmic actin filaments reorganized to accumulate beneath the vegetal side of the GV, where the microtubule-organizing center and transient microtubule array (MTOC-TMA) assembled, just before GV breakdown (GVBD). Immediately after GVBD, both Xenopus ADF/cofilin (XAC) and its phosphatase Slingshot (XSSH) accumulated into the nuclei and intranuclear actin filaments disassembled from the vegetal side with the shrinkage of the GV. As the MTOC-TMA developed well, cytoplasmic actin filaments were retained at the MTOC-TMA base region. Suppression of XAC dephosphorylation by anti-XSSH antibody injection inhibited both actin filament reorganization and proper formation and localization of both the MTOC-TMA and meiotic spindles. Stabilization of actin filaments by phalloidin also inhibited formation of the MTOC-TMA and disassembly of intranuclear actin filaments without affecting nuclear shrinkage. Nocodazole also caused the MTOC-TMA and the cytoplasmic actin filaments at its base region to disappear, which further impeded disassembly of intranuclear actin filaments from the vegetal side. XAC appears to reorganize cytoplasmic actin filaments required for precise assembly of the MTOC and, together with the MTOC-TMA, regulate the intranuclear actin filament disassembly essential for meiotic spindle formation.

scholarly journals Induction of maturation-promoting factor during Xenopus oocyte maturation uncouples Ca2+ store depletion from store-operated Ca2+ entry

2002 ◽  
Vol 156 (1) ◽  
pp. 75-86 ◽  
Author(s):  
Khaled Machaca ◽  
Shirley Haun
Keyword(s):  
Oocyte Maturation ◽  
Xenopus Oocyte ◽  
Medical Science ◽  
Germinal Vesicle ◽  
Mitogen Activated Protein Kinase ◽  
Egg Activation ◽  
Germinal Vesicle Breakdown ◽  
Store Depletion ◽  
Oocyte Meiosis ◽  
Maturation Promoting Factor

Department of Physiology and Biophysics, University of Arkansas Medical Science, Little Rock, AR 72205 During oocyte maturation, eggs acquire the ability to generate specialized Ca2+ signals in response to sperm entry. Such Ca2+ signals are crucial for egg activation and the initiation of embryonic development. We examined the regulation during Xenopus oocyte maturation of store-operated Ca2+ entry (SOCE), an important Ca2+ influx pathway in oocytes and other nonexcitable cells. We have previously shown that SOCE inactivates during Xenopus oocyte meiosis. SOCE inactivation may be important in preventing premature egg activation. In this study, we investigated the correlation between SOCE inactivation and the Mos–mitogen-activated protein kinase (MAPK)–maturation-promoting factor (MPF) kinase cascade, which drives Xenopus oocyte maturation. SOCE inactivation at germinal vesicle breakdown coincides with an increase in the levels of MAPK and MPF. By differentially inducing Mos, MAPK, and MPF, we demonstrate that the activation of MPF is necessary for SOCE inactivation during oocyte maturation. In contrast, sustained high levels of Mos kinase and the MAPK cascade have no effect on SOCE activation. We further show that preactivated SOCE is not inactivated by MPF, suggesting that MPF does not block Ca2+ influx through SOCE channels, but rather inhibits coupling between store depletion and SOCE activation.

Transcription of Xenopus tDNAFormula and Sea Urchin Histone DNA Injected into the Xenopus Oocyte Nucleus

1978 ◽  
Vol 42 (0) ◽  
pp. 1077-1082 ◽  
Author(s):  
A. Kressmann ◽  
S. G. Clarkson ◽  
J. L. Telford ◽  
M. L. Birnstiel
Keyword(s):  
Sea Urchin ◽  
Xenopus Oocyte ◽  
Oocyte Nucleus

Aspects of the regulation of histone genes

1978 ◽  
Vol 283 (997) ◽  
pp. 319-324 ◽  
Keyword(s):  
Sea Urchin ◽  
Molecular Mechanisms ◽  
Germinal Vesicle ◽  
Oocyte Nucleus ◽  
Histone Genes ◽  
Structural Genes ◽  
Psammechinus Miliaris

Sequencing of cloned histone DNA of the sea urchin Psammechinus miliaris has confirmed the map of the histone genes obtained earlier by rather less refined techniques. Sequencing of spacer has revealed that it is unlikely to code for protein. Some interesting sequences in the prelude regions to the structural genes have been found. The technique of injecting DNA into the germinal vesicle of the Xenopus oocyte has been greatly simplified, so that now many of the parameters governing the transcription of the injected genes can be investigated. Some mRNA-like molecules appear when circular histone DNA is inserted into the oocyte nucleus. We are cautiously optimistic that the technique can be further developed and will provide a useful tool for the study of the molecular mechanisms governing the expression of structural genes coding for proteins.

Nonhistone Proteins of the Oocyte Nucleus of the Newt

1974 ◽  
Vol 15 (1) ◽  
pp. 145-161
Author(s):  
R. J. HILL ◽  
K. MAUNDRELL ◽  
H. G. CALLAN
Keyword(s):  
Nuclear Membrane ◽  
Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Germinal Vesicle ◽  
Oocyte Nucleus ◽  
Lampbrush Chromosomes ◽  
Nonhistone Proteins ◽  
Aerial Oxidation ◽  
A Minor

Evidence has been obtained which indicates that disulphide bond crosslinks contribute to the morphological integrity of isolated lampbrush chromosomes (both chromomeres and lateral loops) and nucleoli. It is suggested that the progressive formation of these bonds in vitro by aerial oxidation may provide the basis for the previously recognized time-dependent hardening or ‘denaturing’ of these structures. Manually isolated germinal vesicle nuclei have been massed and fractionated by low-speed centrifugation into nucleoplasm and chromatin. Phase-contrast microscopy demonstrates the chromatin to consist of nucleoli, lampbrush chromosomes and nuclear membranes. Urea gel electrophoresis has been employed to resolve the reduced and S-carboxymethylated proteins of whole nuclei into some 12 components, negatively charged at pH 8. The nucleoplasm alone gives an essentially similar pattern, but with the distinct depletion of one component and slight depletion of another. Both of these components are much enriched in the chromatin pellet where they predominate over all other proteins. The total chromatin has been subfractionated by microdissection, taking advantage of the differential attachment of nucleoli to the nuclear membrane at different stages of oogenesis. It is concluded that the nuclear membrane per se does not contribute to the major chromatin proteins. The two major polypeptides are components of the nucleoli. Preparations of isolated lampbrush chromosomes have not, to date, provided sufficient material to give a distinctive electropherogram; only one faint band, a major component of whole nuclei, was apparent. Sodium dodecyl sulphate gel electrophoresis has resolved some 25 components in whole nuclei, and again demonstrates the enrichment of the two major species in the total chromatin fraction. The apparent molecular weights of these two species are 43 kilodaltons and 110 kilodaltons. Approximately 20 minor species are also present in the chromatin and are obviously good candidates as components of the nucleolar and chromosomal structures. Histones, at most, make only a minor contribution to the overall chromatin protein population.

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