Differential accumulation of oocyte nuclear proteins by embryonic nuclei of Xenopus

Development ◽  
1987 ◽  
Vol 101 (4) ◽  
pp. 829-846 ◽  
Author(s):  
C. Dreyer
Keyword(s):  
De Novo ◽  
Germinal Vesicle ◽  
Intrinsic Property ◽  
Nuclear Proteins ◽  
Cell Nuclei ◽  
Germinal Vesicle Breakdown ◽  
Early Stages ◽  
Nuclear Antigens ◽  
Gradual Process ◽  
Oocyte Nuclear Proteins

Oocyte nuclear proteins of Xenopus are distributed into the cytoplasm of the maturing egg after germinal vesicle breakdown. Later they are found in all cell nuclei of the embryo. At early stages of development, different nuclear proteins behave differently. A class of ‘early shifting’ antigens is accumulated by pronuclei and cleavage nuclei, whereas others appear to be excluded from the nuclei at early stages but are shifted into the nuclei at blastula or during and after gastrulation. Accumulation of ‘late-shifting’ nuclear antigens is a gradual process and occurs during a period characteristic of each protein. Multiple artificial pronuclei can be formed after injection of sperm nuclei, erythrocyte nuclei or pure lambda-DNA into unfertilized eggs. The artificial pronuclei accumulate early- but not late-shifting proteins. Early-migrating proteins rapidly accumulate into the germinal vesicle after de novo synthesis in the oocyte, indicating that the efficiency of translocation into nuclei is an intrinsic property of each protein. Artificial extension of the length of the cell cycle before midblastula transition does not lead to accumulation of the late-shifting nuclear antigens investigated.

scholarly journals Subcellular analyses of planarian meiosis implicates a novel, double-membraned vesiculation process in nuclear envelope breakdown

2019 ◽  
Author(s):  
Longhua Guo ◽  
Fengli Guo ◽  
Shasha Zhang ◽  
Kexi Yi ◽  
Melainia McClain ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
De Novo ◽  
Germinal Vesicle ◽  
Protein Composition ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Cell Nuclei ◽  
Germinal Vesicle Breakdown ◽  
Evolutionary Origins ◽  
Pore Complexes

AbstractThe cell nuclei of Ophisthokonts, the eukaryotic supergroup defined by fungi and metazoans, is remarkable in the constancy of both their double-membraned structure and protein composition. Such remarkable structural conservation underscores common and ancient evolutionary origins. Yet, the dynamics of disassembly and reassembly displayed by Ophisthokont nuclei vary extensively. Besides closed mitosis in fungi and open mitosis in some animals, little is known about the evolution of nuclear envelope break down (NEBD) during cell division. Here, we uncovered a novel form of NEBD in primary oocytes of the flatworm Schmidtea mediterranea. From zygotene to metaphase II, both nuclear envelope (NE) and peripheral endoplasmic reticulum (ER) expand notably in size, likely involving de novo membrane synthesis. 3-D electron microscopy reconstructions demonstrated that the NE transforms itself into numerous double-membraned vesicles similar in membrane architecture to NE doublets in mammalian oocytes after germinal vesicle breakdown. The vesicles are devoid of nuclear pore complexes and DNA, yet are loaded with nuclear proteins, including a planarian homologue of PIWI, a protein essential for the maintenance of stem cells in this and other organisms. Our data contribute a new model to the canonical view of NE dynamics and support that NEBD is an evolutionarily adaptable trait in multicellular organisms.

Meiosis and embryo technology: renaissance of the nucleolus

2005 ◽  
Vol 17 (2) ◽  
pp. 3 ◽  
Author(s):  
Poul Maddox-Hyttel ◽  
Bolette Bjerregaard ◽  
Jozef Laurincik
Keyword(s):  
Topoisomerase I ◽  
De Novo ◽  
Germinal Vesicle ◽  
Developmental Competence ◽  
Rdna Transcription ◽  
Morphological Marker ◽  
Germinal Vesicle Breakdown ◽  
Oocyte Growth ◽  
Embryonic Genome

The nucleolus is the site of rRNA and ribosome production. This organelle presents an active fibrillogranular ultrastructure in the oocyte during the growth of the gamete but, at the end of the growth phase, the nucleolus is transformed into an inactive remnant that is dissolved when meiosis is resumed at germinal vesicle breakdown. Upon meiosis, structures resembling the nucleolar remnant, now referred to as nucleolus precursor bodies (NPBs), are established in the pronuclei. These entities harbour the development of fibrillogranular nucleoli and re-establishment of nucleolar function in conjunction with the major activation of the embryonic genome. This so-called nucleologenesis occurs at a species-specific time of development and can be classified into two different models: one where nucleolus development occurs inside the NPBs (e.g. cattle) and one where the nucleolus is formed on the surface of the NPBs (e.g. pigs). A panel of nucleolar proteins with functions during rDNA transcription (topoisomerase I, RNA polymerase I and upstream binding factor) and early (fibrillarin) or late rRNA processing (nucleolin and nucleophosmin) are localised to specific compartments of the oocyte nucleolus and those engaged in late processing are, to some degree, re-used for nucleologenesis in the embryo, whereas the others require de novo embryonic transcription in order to be allocated to the developing nucleolus. In the oocyte, inactivation of the nucleolus coincides with the acquisition of full meiotic competence, a parameter that may be of importance in relation to in vitro oocyte maturation. In embryo, nucleologenesis may be affected by technological manipulations: in vitro embryo production apparently has no impact on this process in cattle, whereas in the pig this technology results in impaired nucleologenesis. In cattle, reconstruction of embryos by nuclear transfer results in profound disturbances in nucleologenesis. In conclusion, the nucleolus is an organelle of great importance for the developmental competence of oocytes and embryos and may serve as a morphological marker for the completion of oocyte growth and normality of activation of the embryonic genome.

256 SWITCH IN THE EXPRESSION OF GENES INVOLVED IN LIPID METABOLISM FOR IN VIVO-MATURED BOVINE OOCYTES AND BLASTOCYSTS

2007 ◽  
Vol 19 (1) ◽  
pp. 244 ◽  
Author(s):  
O. Algriany ◽  
P. L. A. M. Vos ◽  
M. A. Sirard ◽  
S. J. Dieleman
Keyword(s):  
Lipid Metabolism ◽  
Oocyte Maturation ◽  
De Novo ◽  
Energy Requirement ◽  
Germinal Vesicle ◽  
Blastocyst Stage ◽  
Germinal Vesicle Breakdown ◽  
Cpt I ◽  
Bovine Oocytes

The competence of oocytes to develop into healthy offspring is determined by many factors including oocyte quality, embryo culture conditions, and energy requirements. Although glucose metabolism has been studied extensively, little is known about lipid metabolism during oocyte maturation and in the blastocyst. In general, cells can obtain fatty acids (FA) by transport (1) from outside across the cell membrane or by synthesis (2) inside the cell, and loose FA by catabolic processes (3). Therefore, we analyzed mRNA abundance for (1) FA translocase (FAT/CD36) and FA transport protein (FATP1), (2) acetyl-CoA carboxylase (ACC) α and FA synthase (FAS), and (3) AMP-activated protein kinase gamma 1 (AMPK) and carnitine palmitoyltransferase I (CPT-I) in bovine oocytes during resumption of meiosis in vivo vs.in vivo blastocysts. Cyclic Holstein-Friesian cows (n = 16) were treated with oFSH and a controlled LH surge (Knijn et al. 2002 Reproduction 124, 365–375) to collect oocytes at onset of maturation, 2 h before LH, and after the start of germinal vesicle breakdown (6 h after LH). A second group of cows (n = 10) was treated with eCG/anti-eCG (Voset al. 1994 Theriogenology 41, 829–840) to flush blastocysts at Day 7 after ovulation. Following ovariectomy, oocytes from all follicles between 10 and 18 mm were denuded and stored separately at -80�C. Oocytes were selected on the basis of the relative steroid concentration in the follicular fluid, producing 3 replicate pools of 13 competent oocytes each, at both 2 h before and 6 h after LH. Four replicates of 5 expanded blastocysts grade 1 (IETS) each were stored at -80�C. Total RNA was isolated using a microspin column, and DNA was digested (Absolutely RNA Microprep Kit; Stratagene, San Diego, CA, USA) and reverse transcribed using the iScript cDNA Synthesis Kit (Bio-Rad Laboratories, Hercules, CA, USA). Amplification of cDNA was achieved by real-time PCR using specific primers and 2X iQ SYBR Green Supermix (Bio-Rad Laboratories) in duplicate. Relative levels of expression were analyzed using a modified delta-Ct method. Statistical analysis was done using ANOVA and the Tukey post-hoc test. Relative abundance of mRNA for FA transport and catabolism was >10 times higher during oocyte maturation than in blastocysts; CPT-I was not detected in blastocysts. In contrast, transcripts of FA synthesis were sharply increased (>5 times) during the blastocyst stage. Alterations in the expression of these mRNA indicate that they play a key role in mediating cell type-specific differences in energy requirement and that exogenous FA and FA catabolism could be a main source of energy during oocyte maturation. A high level of FA biosynthesis mRNA in blastocysts may reflect high demands of de novo long-chain FA synthesis and elongation that probably are essential for protection against stress.

PLCz-induced Ca2+ oscillations are enhanced after germinal vesicle breakdown during mouse oocyte maturation

2016 ◽  
Author(s):  
Jessica Sanders ◽  
Ethan Bateson ◽  
Yuansong Yu ◽  
Michail Nomikos ◽  
Antony Lai ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Germinal Vesicle ◽  
Mouse Oocyte ◽  
Germinal Vesicle Breakdown

scholarly journals The microbiota is dispensable for the early stages of peripheral regulatory T cell induction within mesenteric lymph nodes

2021 ◽  
Author(s):  
Carolin Wiechers ◽  
Mangge Zou ◽  
Eric Galvez ◽  
Michael Beckstette ◽  
Maria Ebel ◽  
...  
Keyword(s):  
T Cell ◽  
Lymph Nodes ◽  
Regulatory T Cell ◽  
De Novo ◽  
Bacterial Species ◽  
Short Chain Fatty Acids ◽  
Mesenteric Lymph Nodes ◽  
Direct Role ◽  
Early Stages ◽  
Mesenteric Lymph

AbstractIntestinal Foxp3+ regulatory T cell (Treg) subsets are crucial players in tolerance to microbiota-derived and food-borne antigens, and compelling evidence suggests that the intestinal microbiota modulates their generation, functional specialization, and maintenance. Selected bacterial species and microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), have been reported to promote Treg homeostasis in the intestinal lamina propria. Furthermore, gut-draining mesenteric lymph nodes (mLNs) are particularly efficient sites for the generation of peripherally induced Tregs (pTregs). Despite this knowledge, the direct role of the microbiota and their metabolites in the early stages of pTreg induction within mLNs is not fully elucidated. Here, using an adoptive transfer-based pTreg induction system, we demonstrate that neither transfer of a dysbiotic microbiota nor dietary SCFA supplementation modulated the pTreg induction capacity of mLNs. Even mice housed under germ-free (GF) conditions displayed equivalent pTreg induction within mLNs. Further molecular characterization of these de novo induced pTregs from mLNs by dissection of their transcriptomes and accessible chromatin regions revealed that the microbiota indeed has a limited impact and does not contribute to the initialization of the Treg-specific epigenetic landscape. Overall, our data suggest that the microbiota is dispensable for the early stages of pTreg induction within mLNs.

scholarly journals Control of germinal vesicle breakdown in bovine x murine hybrid oocytes

1993 ◽  
Vol 33 (5) ◽  
pp. 411-417 ◽  
Author(s):  
J. Fulka ◽  
ML Leibfried-Rutledge ◽  
NL First
Keyword(s):  
Germinal Vesicle ◽  
Germinal Vesicle Breakdown

scholarly journals Requirement of mosXe protein kinase for meiotic maturation of Xenopus oocytes induced by a cdc2 mutant lacking regulatory phosphorylation sites.

1992 ◽  
Vol 12 (7) ◽  
pp. 3192-3203 ◽  
Author(s):  
K M Pickham ◽  
A N Meyer ◽  
J Li ◽  
D J Donoghue
Keyword(s):  
Protein Kinase ◽  
Oocyte Maturation ◽  
Xenopus Oocytes ◽  
Germinal Vesicle ◽  
Cyclin B1 ◽  
Phosphorylation Sites ◽  
Germinal Vesicle Breakdown ◽  
Regulatory Phosphorylation

The p34cdc2 protein kinase is a component of maturation-promoting factor, the master regulator of the cell cycle in all eukaryotes. The activity of p34cdc2 is itself tightly regulated by phosphorylation and dephosphorylation. Predicted regulatory phosphorylation sites of Xenopus p34cdc2 were mutated in vitro, and in vitro-transcribed RNAs were injected into Xenopus oocytes. The cdc2 single mutants Thr-14----Ala and Tyr-15----Phe did not induce germinal vesicle breakdown (BVBD) upon microinjection into oocytes. In contrast, the cdc2 double mutant Ala-14/Phe-15 did induce GVBD. Both the Ala-14 and Ala-14/Phe-15p34cdc2 mutants were shown to coimmunoprecipitate cyclin B1 and to phosphorylate histone H1 in immune complex kinase assays. Microinjection of antisense oligonucleotides to c-mosXe was used to demonstrate the role of mos protein synthesis in the induction of GVBD by the Ala-14/Phe-15 cdc2 mutant. Thr-161 was also mutated. p34cdc2 single mutants Ala-161 and Glu-161 and triple mutants Ala-14/Phe-15/Ala-161 and Ala-14/Phe-15/Glu-161 failed to induce GVBD in oocytes and showed a decreased binding to cyclin B1 in coimmunoprecipitations. Each of the cdc2 mutants was also assayed by coinjection with cyclin B1 or c-mosXe RNA into oocytes. Several of the cdc2 mutants were found to affect the kinetics of cyclin B1 and/or mos-induced GVBD upon coinjection, although none affected the rate of progesterone-induced maturation. We demonstrate here the significance of Thr-14, Tyr-15, and Thr-161 of p34cdc2 in Xenopus oocyte maturation. In addition, these results suggest a regulatory role for mosXe in induction of oocyte maturation by the cdc2 mutant Ala-14/Phe-15.

Oocyte maturation: aberrant post-fusion responses of the rabbit primary oocyte to penetrating spermatozoa

1979 ◽  
Vol 39 (1) ◽  
pp. 1-12
Author(s):  
M. Berrios ◽  
J.M. Bedford
Keyword(s):  
Anterior Part ◽  
Light And Electron Microscopy ◽  
Germinal Vesicle ◽  
Sperm Chromatin ◽  
Fallopian Tubes ◽  
Cortical Granules ◽  
Germinal Vesicle Breakdown ◽  
Acrosomal Membrane ◽  
Primary Oocyte ◽  
Inner Acrosomal Membrane

Primary oocytes cannot be fertilized normally; they begin to develop this capacity as meiosis resumes. To elucidate the changes involved in acquisition of their fertilizability, rabbit primary oocytes displaying a germinal vesicle (GV oocytes) were placed in Fallopian tubes inseminated previously with spermatozoa, recovered 2–5 h later and examined by light and electron microscopy. At least 4 aspects of GV oocyte/sperm interaction were abnormal. Although the vestments and oolemma seem normally receptive to spermatozoa, fusion with the oolemma of the primary oocyte did not elicit exocytosis of cortical granules, and consequently multiple entry of spermatozoa into the ooplasm was common. Secondly, the GV oocyte cortex failed to achieve a normal englufment of the anterior part of the sperm head. It sank into the ooplasm capped by only a small rostral vesicle or left the stable inner acrosomal membrane as a patch in the oolemma. Only rarely then was there significant dispersion of the sperm chromatin, and this remained surrounded by nuclear envelope. The persistence of this envelope constitutes a further aberrant feature, for it disappears immediately in secondary oocytes and was absent in primary oocytes in which germinal vesicle breakdown had occurred. The results are discussed with particular reference to current ideas about male pronucleus formation.

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