Phases of cytoplasmic and cortical reorganizations of the ascidian zygote between fertilization and first division

Development ◽  
1999 ◽  
Vol 126 (14) ◽  
pp. 3101-3117
Author(s):  
F. Roegiers ◽  
C. Djediat ◽  
R. Dumollard ◽  
C. Rouviere ◽  
C. Sardet
Keyword(s):  
Cell Cycle ◽  
Imaging Techniques ◽  
Cell Types ◽  
Meiotic Cell ◽  
Cytoplasmic Domains ◽  
Cell Stage ◽  
Rich Domain ◽  
Vegetal Cortex ◽  
Transplantation Experiments ◽  
Sperm Aster

Many eggs undergo reorganizations that localize determinants specifying the developmental axes and the differentiation of various cell types. In ascidians, fertilization triggers spectacular reorganizations that result in the formation and localization of distinct cytoplasmic domains that are inherited by early blastomeres that develop autonomously. By applying various imaging techniques to the transparent eggs of Phallusia mammillata, we now define 9 events and phases in the reorganization of the surface, cortex and the cytoplasm between fertilization and first cleavage. We show that two of the domains that preexist in the egg (the ER-rich cortical domain and the mitochondria-rich subcortical myoplasm) are localized successively by a microfilament-driven cortical contraction, a microtubule-driven migration and rotation of the sperm aster with respect to the cortex, and finally, a novel microfilament-dependant relaxation of the vegetal cortex. The phases of reorganization we have observed can best be explained in terms of cell cycle-regulated phases of coupling, uncoupling and recoupling of the motions of cortical and subcortical layers (ER-rich cortical domain and mitochondria-rich domain) with respect to the surface of the zygote. At the end of the meiotic cell cycle we can distinguish up to 5 cortical and cytoplasmic domains (including two novel ones; the vegetal body and a yolk-rich domain) layered against the vegetal cortex. We have also analyzed how the myoplasm is partitioned into distinct blastomeres at the 32-cell stage and the effects on development of the ablation of precisely located small fragments. On the basis of our observations and of the ablation/ transplantation experiments done in the zygotes of Phallusia and several other ascidians, we suggest that the determinants for unequal cleavage, gastrulation and for the differentiation of muscle and endoderm cells may reside in 4 distinct cortical and cytoplasmic domains localized in the egg between fertilization and cleavage.

Organization and regulation of cortical microtubules during the first cell cycle of Xenopus eggs

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 699-709 ◽  
Author(s):  
M.M. Schroeder ◽  
D.L. Gard
Keyword(s):  
Cell Cycle ◽  
Cortical Microtubule ◽  
Cortical Microtubules ◽  
Confocal Immunofluorescence Microscopy ◽  
Confocal Immunofluorescence ◽  
Vegetal Cortex ◽  
M Phase ◽  
Tubulin Antibodies ◽  
Microtubule Networks ◽  
Sperm Aster

Anti-tubulin antibodies and confocal immunofluorescence microscopy were used to examine the organization and regulation of cytoplasmic and cortical microtubules during the first cell cycle of fertilized Xenopus eggs. Appearance of microtubules in the egg cortex temporally coincided with the outgrowth of the sperm aster. Microtubules of the sperm aster first reached the animal cortex at 0.25, (times normalized to first cleavage), forming a radially organized array of cortical microtubules. A disordered network of microtubules was apparent in the vegetal cortex as early as 0.35. Cortical microtubule networks of both animal and vegetal hemispheres were reorganized at times corresponding to the cortical rotation responsible for specification of the dorsal-ventral (D-V) axis. Optical sections suggest that the cortical microtubules are continuous with the microtubules of the sperm aster in fertilized eggs, or an extensive activation aster in activated eggs. Neither assembly and organization, nor disassembly of the cortical microtubules coincided with MPF activation during mitosis. However, cycloheximide or 6-dimethylaminopurine, which arrest fertilized eggs at interphase, blocked cortical microtubule disassembly. Injection of p13, a protein that specifically inhibits MPF activation, delayed or inhibited cortical microtubule breakdown. In contrast, eggs injected with cyc delta 90, a truncated cyclin that arrest eggs in M-phase, showed normal microtubule disassembly. Finally, injection of partially purified MPF into cycloheximide-arrested eggs induced cortical microtubule breakdown. These results suggest that, despite a lack of temporal coincidence, breakdown of the cortical microtubules is dependent on the activation of MPF.

par-4, a gene required for cytoplasmic localization and determination of specific cell types in Caenorhabditis elegans embryogenesis.

Genetics ◽  
1992 ◽  
Vol 130 (4) ◽  
pp. 771-790 ◽  
Author(s):  
D G Morton ◽  
J M Roos ◽  
K J Kemphues
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Types ◽  
Intestinal Cells ◽  
Specific Cell ◽  
Cytoplasmic Localization ◽  
Loss Of Function ◽  
Embryo Viability ◽  
Cell Stage ◽  
Maternal Genome

Abstract Specification of some cell fates in the early Caenorhabditis elegans embryo is mediated by cytoplasmic localization under control of the maternal genome. Using nine newly isolated mutations, and two existing mutations, we have analyzed the role of the maternally expressed gene par-4 in cytoplasmic localization. We recovered seven new par-4 alleles in screens for maternal effect lethal mutations that result in failure to differentiate intestinal cells. Two additional par-4 mutations were identified in noncomplementation screens using strains with a high frequency of transposon mobility. All 11 mutations cause defects early in development of embryos produced by homozygous mutant mothers. Analysis with a deficiency in the region indicates that it33 is a strong loss-of-function mutation. par-4(it33) terminal stage embryos contain many cells, but show no morphogenesis, and are lacking intestinal cells. Temperature shifts with the it57ts allele suggest that the critical period for both intestinal differentiation and embryo viability begins during oogenesis, about 1.5 hr before fertilization, and ends before the four-cell stage. We propose that the primary function of the par-4 gene is to act as part of a maternally encoded system for cytoplasmic localization in the first cell cycle, with par-4 playing a particularly important role in the determination of intestine. Analysis of a par-4; par-2 double mutant suggests that par-4 and par-2 gene products interact in this system.

scholarly journals Histone modifications form a cell-type-specific chromosomal bar code that persists through the cell cycle

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
John A. Halsall ◽  
Simon Andrews ◽  
Felix Krueger ◽  
Charlotte E. Rutledge ◽  
Gabriella Ficz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Histone Modifications ◽  
Expression Patterns ◽  
Cell Types ◽  
Cell Type ◽  
Bar Code ◽  
Genes Encoding ◽  
Cell Type Specific ◽  
Rolling Windows

AbstractChromatin configuration influences gene expression in eukaryotes at multiple levels, from individual nucleosomes to chromatin domains several Mb long. Post-translational modifications (PTM) of core histones seem to be involved in chromatin structural transitions, but how remains unclear. To explore this, we used ChIP-seq and two cell types, HeLa and lymphoblastoid (LCL), to define how changes in chromatin packaging through the cell cycle influence the distributions of three transcription-associated histone modifications, H3K9ac, H3K4me3 and H3K27me3. We show that chromosome regions (bands) of 10–50 Mb, detectable by immunofluorescence microscopy of metaphase (M) chromosomes, are also present in G1 and G2. They comprise 1–5 Mb sub-bands that differ between HeLa and LCL but remain consistent through the cell cycle. The same sub-bands are defined by H3K9ac and H3K4me3, while H3K27me3 spreads more widely. We found little change between cell cycle phases, whether compared by 5 Kb rolling windows or when analysis was restricted to functional elements such as transcription start sites and topologically associating domains. Only a small number of genes showed cell-cycle related changes: at genes encoding proteins involved in mitosis, H3K9 became highly acetylated in G2M, possibly because of ongoing transcription. In conclusion, modified histone isoforms H3K9ac, H3K4me3 and H3K27me3 exhibit a characteristic genomic distribution at resolutions of 1 Mb and below that differs between HeLa and lymphoblastoid cells but remains remarkably consistent through the cell cycle. We suggest that this cell-type-specific chromosomal bar-code is part of a homeostatic mechanism by which cells retain their characteristic gene expression patterns, and hence their identity, through multiple mitoses.

Hydrogen peroxide modulates meiotic cell cycle and induces morphological features characteristic of apoptosis in rat oocytes cultured in vitro

APOPTOSIS ◽  
2005 ◽  
Vol 10 (4) ◽  
pp. 863-874 ◽  
Author(s):  
S. K. Chaube ◽  
P. V. Prasad ◽  
S. C. Thakur ◽  
T. G. Shrivastav
Keyword(s):  
Cell Cycle ◽  
Hydrogen Peroxide ◽  
Morphological Features ◽  
Meiotic Cell

Involvement of caveolin-1 in meiotic cell-cycle progression in Caenorhabditis elegans

10.1038/10100 ◽  
1999 ◽  
Vol 1 (2) ◽  
pp. 127-129 ◽  
Author(s):  
Jochen Scheel ◽  
Jagan Srinivasan ◽  
Ulrike Honnert ◽  
Annemarie Henske ◽  
Teymuras V. Kurzchalia
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Cell Cycle Progression ◽  
Meiotic Cell ◽  
Cycle Progression ◽  
Caveolin 1

Identification of the Xenopus 20S proteasome α4 subunit which is modified in the meiotic cell cycle

Gene ◽  
1999 ◽  
Vol 239 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Mika Tokumoto ◽  
Ryo Horiguchi ◽  
Yoshitaka Nagahama ◽  
Toshinobu Tokumoto
Keyword(s):  
Cell Cycle ◽  
20S Proteasome ◽  
Meiotic Cell

A novel H+ permeability dominating intracellular pH in the early mouse embryo

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1353-1361
Author(s):  
J.M. Baltz ◽  
J.D. Biggers ◽  
C. Lechene
Keyword(s):  
Plasma Membrane ◽  
Intracellular Ph ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Types ◽  
Preimplantation Embryos ◽  
Developmentally Regulated ◽  
Cell Stage ◽  
K Concentration ◽  
Early Mouse

Most cell types are relatively impermeant to H+ and are able to regulate their intracellular pH by means of plasma membrane proteins, which transport H+ or bicarbonate across the membrane in response to perturbations of intracellular pH. Mouse preimplantation embryos at the 2-cell stage, however, do not appear to possess specific pH-regulatory mechanisms for relieving acidosis. They are, instead, highly permeable to H+, so that the intracellular pH in the acid and neutral range is determined by the electrochemical equilibrium of H+ across the plasma membrane. When intracellular pH is perturbed, the rate of the ensuing H+ flux across the plasma membrane is determined by the H+ electrochemical gradient: its dependence on external K+ concentration indicates probable dependence on membrane potential and the rate depends on the H+ concentration gradient across the membrane. The large permeability at the 2-cell stage is absent or greatly diminished in the trophectoderm of blastocysts, but still present in the inner cell mass. Thus, the permeability to H+ appears to be developmentally regulated.

scholarly journals CNOT 6L couples the selective degradation of maternal transcripts to meiotic cell cycle progression in mouse oocyte

2018 ◽  
Vol 37 (24) ◽  
Author(s):  
Qian‐Qian Sha ◽  
Jia‐Li Yu ◽  
Jing‐Xin Guo ◽  
Xing‐Xing Dai ◽  
Jun‐Chao Jiang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Mouse Oocyte ◽  
Meiotic Cell ◽  
Cycle Progression ◽  
Selective Degradation ◽  
Maternal Transcripts

scholarly journals A NIMA-related Kinase, Fa2p, Localizes to a Novel Site in the Proximal Cilia of Chlamydomonas and Mouse Kidney Cells

2004 ◽  
Vol 15 (11) ◽  
pp. 5172-5186 ◽  
Author(s):  
Moe R. Mahjoub ◽  
M. Qasim Rasi ◽  
Lynne M. Quarmby
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cell Types ◽  
Mouse Kidney ◽  
Kidney Cells ◽  
Polycystic Kidney ◽  
Cycle Progression ◽  
Cystic Kidneys ◽  
Ciliary Function ◽  
The Relationship

Polycystic kidney disease and related syndromes involve dysregulation of cell proliferation in conjunction with ciliary defects. The relationship between cilia and cell cycle is enigmatic, but it may involve regulation by the NIMA-family of kinases (Neks). We previously showed that the Nek Fa2p is important for ciliary function and cell cycle in Chlamydomonas. We now show that Fa2p localizes to an important regulatory site at the proximal end of cilia in both Chlamydomonas and a mouse kidney cell line. Fa2p also is associated with the proximal end of centrioles. Its localization is dynamic during the cell cycle, following a similar pattern in both cell types. The cell cycle function of Fa2p is kinase independent, whereas its ciliary function is kinase dependent. Mice with mutations in Nek1 or Nek8 have cystic kidneys; therefore, our discovery that a member of this phylogenetic group of Nek proteins is localized to the same sites in Chlamydomonas and kidney epithelial cells suggests that Neks play conserved roles in the coordination of cilia and cell cycle progression.

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