Adenosine induces dormancy in starfish blastulae

Development ◽  
1988 ◽  
Vol 103 (2) ◽  
pp. 345-351
Author(s):  
N. Tsuchimori ◽  
S. Miyashiro ◽  
H. Shibai ◽  
S. Ikegami
Keyword(s):  
Epithelial Cells ◽  
Sea Water ◽  
Intracellular Concentration ◽  
Normal Embryo ◽  
Embryonic Cells ◽  
Macromolecular Synthesis ◽  
Cell Stage ◽  
External Application ◽  
Dna And Rna ◽  
Asterina Pectinifera

External application of 50 micrograms ml-1 adenosine inhibits development of the starfish Asterina pectinifera at the 256-cell stage when all the embryonic cells differentiate to epithelial cells. Intracellular concentration of adenosine in the adenosine-treated embryo is 2.7 times higher than those of the normal embryo whereas the contents of ATP, ADP, AMP and adenosine 3′,5′-monophosphate are the same for both embryos. Adenosine causes more than 95% reduction in the rate of protein, DNA and RNA syntheses. By returning the embryo to normal sea water, macromolecular synthesis restarts and the embryo develops to the bipinnaria stage.

Altered expression of spatially regulated embryonic genes in the progeny of separated sea urchin blastomeres

Development ◽  
1989 ◽  
Vol 106 (3) ◽  
pp. 567-579 ◽  
Author(s):  
D.L. Hurley ◽  
L.M. Angerer ◽  
R.C. Angerer
Keyword(s):  
Cell Fate ◽  
Sea Urchin ◽  
Sea Water ◽  
Negative Control ◽  
Normal Embryo ◽  
Cell Stage ◽  
Mrna Accumulation ◽  
Altered Expression ◽  
Intact Embryo ◽  
Dissociated Cells

We have examined the importance of the extracellular environment on the ability of separated cells of sea urchin embryos (Strongylocentrotus purpuratus) to carry out patterns of mRNA accumulation and decay characteristic of intact embryos. Embryos were dissociated into individual blastomeres at 16-cell stage and maintained in calcium-free sea water so that daughter cells continuously separated. Levels of eleven different mRNAs in these cells were compared to those in control embryos when the latter reached mesenchyme blastula stage, by which time cells in major regions of the intact embryo have assumed distinctive patterns of message accumulation. Abrogation of interactions among cells resulted in marked differences in accumulation and/or turnover of the individual mRNAs, which are expressed with diverse temporal and spatial patterns of prevalence in intact embryos. In general, separated cells are competent to execute initial events of mRNA accumulation and decay that occur uniformly in most or all blastomeres of the intact embryo and are likely to be regulated by maternal molecules. The ability of separated cells to accumulate mRNAs that appear slightly later in development depends upon the presumptive tissue in which a given mRNA is found in the normal embryo. Messages that normally accumulate in cells at the vegetal pole also accumulate in dissociated cells either at nearly normal levels or at increased levels. In one such case, that of actin CyIIa, which is normally restricted to mesenchyme cells, in situ hybridization demonstrates that the fraction of dissociated cells expressing this message is 4- to 5-fold higher than in the normal embryo. In contrast, separated cells accumulate significant levels of a message expressed uniformly in the early ectoderm but are unable to execute accumulation and decay of different messages that distinguish oral and aboral ectodermal regions. These data are consistent with the idea that interactions among cells in the intact embryo are important for both positive and negative control of expression of different genes that are early indicators of the specification of cell fate.

Reconstruction of bipinnaria larvae from dissociated embryonic cells of the starfish, Asterina pectinifera

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 47-60
Author(s):  
M. Dan-Sohkawa ◽  
H. Yamanaka ◽  
K. Watanabe
Keyword(s):  
Intestinal Lumen ◽  
Normal Embryo ◽  
Embryonic Cells ◽  
Reconstruction Process ◽  
Stage 4 ◽  
Internal Cavities ◽  
Optimal Population ◽  
Stage 1 ◽  
Asterina Pectinifera ◽  
Number Of Cells

Cells dissociated from swimming embryos of the starfish are able to reconstruct bipinnaria larvae. This process consists of reaggregation (stage 1), formation of the external epithelium (stage 2), development of the internal cavities which will eventually grow either into the blastocoel or the intestinal lumen (stage 3), gastrulation or fusion of the internal and the external epithelia (stage 4), formation of the mouth (stage 5) and the established bipinnaria (stage 6). The optimal population of cells to support the process of reconstruction is estimated to fall between 500 and 1000, values corresponding to one eighth and one fourth the total number of cells of a normal embryo, respectively. Morphogenetic events of reconstruction are discussed in relation to the normal course of starfish development and to the reconstruction process of the sea urchin.

Continuum model of epithelial morphogenesis during Caenorhabditis elegans embryonic elongation

2009 ◽  
Vol 367 (1902) ◽  
pp. 3379-3400 ◽  
Author(s):  
P. Ciarletta ◽  
M. Ben Amar ◽  
M. Labouesse
Keyword(s):  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Molecular Motor ◽  
Biomechanical Model ◽  
Epithelial Morphogenesis ◽  
Embryonic Cells ◽  
Microtubule Network ◽  
Theoretical Predictions ◽  
Elongation Process ◽  
Muscle Myosin

The purpose of this work is to provide a biomechanical model to investigate the interplay between cellular structures and the mechanical force distribution during the elongation process of Caenorhabditis elegans embryos. Epithelial morphogenesis drives the elongation process of an ovoid embryo to become a worm-shaped embryo about four times longer and three times thinner. The overall anatomy of the embryo is modelled in the continuum mechanics framework from the structural organization of the subcellular filaments within epithelial cells. The constitutive relationships consider embryonic cells as homogeneous materials with an active behaviour, determined by the non-muscle myosin II molecular motor, and a passive viscoelastic response, related to the directional properties of the filament network inside cells. The axisymmetric elastic solution at equilibrium is derived by means of the incompressibility conditions, the continuity conditions for the overall embryo deformation and the balance principles for the embryonic cells. A particular analytical solution is proposed from a simplified geometry, demonstrating the mechanical role of the microtubule network within epithelial cells in redistributing the stress from a differential contraction of circumferentially oriented actin filaments. The theoretical predictions of the biomechanical model are discussed within the biological scenario proposed through genetic analysis and pharmacological experiments.

Mouse one-cell embryos undergoing a radiation-induced G2 arrest may re-enter S-phase in the absence of cytokinesis

2002 ◽  
Vol 80 (7) ◽  
pp. 618-624 ◽  
Author(s):  
P Jacquet ◽  
J Buset ◽  
J Vankerkom ◽  
S Baatout ◽  
L de Saint-Georges ◽  
...  
Keyword(s):  
Calyculin A ◽  
Embryonic Cells ◽  
G2 Arrest ◽  
Cell Stage ◽  
Chromosome Fragments ◽  
X Irradiation ◽  
Radiation Induced ◽  
Mouse Zygotes ◽  
The One

PCC (premature chromosome condensation) can be used for visualizing and scoring damage induced by radiation in the chromatin of cells undergoing a G1 or G2 arrest. A method involving the fusion of irradiated single embryonic cells with single MI oocytes was used to induce PCC in mouse zygotes of the BALB/c strain, which suffer a drastic G2 arrest after X-irradiation (dose used 2.5 Gy). Other G2-arrested embryos were exposed in vitro to the phosphatase inhibitor calyculin A. Both methods furnished excellent chromosome preparations of the G2-arrested embryos. The mean number of chromosome fragments did not change significantly during G2 arrest, suggesting that zygotes of this strain are unable to repair DNA damage leading to such aberrations. Forty to fifty percent of the irradiated embryos were unable to cleave after G2 arrest and remained blocked at the one-cell stage for a few days before dying. PCC preparations obtained from such embryos suggested that about 30% of them had undergone a late mitosis not followed by cytokinesis and had entered a new DNA synthesis. These results are discussed in the light of recent observations in irradiated human cells deficient in the p53/14-3-3sigma pathway.Key words: PCC, embryo, oocyte, calyculin A, G2 arrest, cytokinesis.

scholarly journals Comparative Analyses of Single-Cell Transcriptomic Profiles between In Vitro Totipotent Blastomere-like Cells and In Vivo Early Mouse Embryonic Cells

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3111
Author(s):  
Po-Yu Lin ◽  
Denny Yang ◽  
Chi-Hsuan Chuang ◽  
Hsuan Lin ◽  
Wei-Ju Chen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Single Cell ◽  
Embryonic Cells ◽  
Cell Stage ◽  
Developmental Potential ◽  
Functional Features ◽  
Early Mouse ◽  
Extraembryonic Tissues

The developmental potential within pluripotent cells in the canonical model is restricted to embryonic tissues, whereas totipotent cells can differentiate into both embryonic and extraembryonic tissues. Currently, the ability to culture in vitro totipotent cells possessing molecular and functional features like those of an early embryo in vivo has been a challenge. Recently, it was reported that treatment with a single spliceosome inhibitor, pladienolide B (plaB), can successfully reprogram mouse pluripotent stem cells into totipotent blastomere-like cells (TBLCs) in vitro. The TBLCs exhibited totipotency transcriptionally and acquired expanded developmental potential with the ability to yield various embryonic and extraembryonic tissues that may be employed as novel mouse developmental cell models. However, it is disputed whether TBLCs are ‘true’ totipotent stem cells equivalent to in vivo two-cell stage embryos. To address this question, single-cell RNA sequencing was applied to TBLCs and cells from early mouse embryonic developmental stages and the data were integrated using canonical correlation analyses. Differential expression analyses were performed between TBLCs and multi-embryonic cell stages to identify differentially expressed genes. Remarkably, a subpopulation within the TBLCs population expressed a high level of the totipotent-related genes Zscan4s and displayed transcriptomic features similar to mouse two-cell stage embryonic cells. This study underscores the subtle differences between in vitro derived TBLCs and in vivo mouse early developmental cell stages at the single-cell transcriptomic level. Our study has identified a new experimental model for stem cell biology, namely ‘cluster 3’, as a subpopulation of TBLCs that can be molecularly defined as near totipotent cells.

Changes in the fine structure of the apical plasma membrane of endometrial epithelial cells during implantation in the rat

1982 ◽  
Vol 55 (1) ◽  
pp. 1-12
Author(s):  
C.R. Murphy ◽  
J.G. Swift ◽  
T.M. Mukherjee ◽  
A.W. Rogers
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Epithelial Cells ◽  
Normal Pregnancy ◽  
Ovariectomized Rats ◽  
Apical Plasma Membrane ◽  
Embryonic Cells ◽  
Blastocyst Implantation ◽  
First Contact ◽  
Endometrial Epithelial Cells

In previous work we have shown that ovarian hormones, when injected into ovariectomized rats, alter the fine structure of the plasma membrane of endometrial epithelial cells. In this paper freeze-fractures have been used to study the apical plasma membrane of endometrial epithelial cells of rats during the period of blastocyst implantation of normal pregnancy. On day 1 of pregnancy there were 2354 +/− 114 intramembranous particles (IMPs) per micrometer2 of membrane. The particles were spherical and randomly distributed. On day 5 of pregnancy IMP density rose to 2899 +/− 289 per micrometer2 and some rod-shaped particles were also visible. By day 6 of pregnancy IMP density had risen to 4014 +/− 206 per micrometer2 and there were more rod-shaped IMPs than before. In addition, on day 6 IMPs were also present as rows of particles and some gap-junction-like arrays of particles were also seen. Our findings indicate that there are fine-structural alterations in the apical plasma membrane of endometrial epithelial cells, the site of first contact between maternal and embryonic cells, during the period of early pregnancy. The findings are discussed in the light of suggested mechanisms of blastocyst attachment to the uterine epithelium at implantation.

Postimplantation development of tetraploid mouse embryos produced by electrofusion

Development ◽  
1990 ◽  
Vol 110 (4) ◽  
pp. 1121-1132
Author(s):  
M.H. Kaufman ◽  
S. Webb
Keyword(s):  
Cytochalasin B ◽  
Histological Analysis ◽  
Mouse Embryos ◽  
Normal Embryo ◽  
Craniofacial Abnormalities ◽  
Success Rates ◽  
Cell Stage ◽  
Extraembryonic Membranes ◽  
Mammalian Embryonic Development ◽  
Viable Embryo

Despite the fact that a variety of experimental techniques have been devised over the years to induce tetraploid mammalian embryonic development, success rates to date have been limited. Apart from the early study by Snow, who obtained development to term of a limited number of cytochalasin B-induced tetraploid mouse embryos, no other researchers have achieved development of tetraploid embryos beyond the early postimplantation period. We now report advanced postimplantation development of tetraploid mouse embryos following electrofusion of blastomeres at the 2-cell stage, and subsequent transfer of these 1-cell ‘fused’ embryos to appropriate recipients. Cytogenetic analysis of the extraembryonic membranes of all of the postimplantation embryos encountered in the present study has provided an unequivocal means of confirming their tetraploid chromosome constitution. A preliminary morphological and histological analysis of the tetraploid embryos obtained by this technique has revealed that characteristic craniofacial abnormalities particularly involving the forebrain and eyes were consistently observed, and these features were often associated with abnormalities of the vertebral axis and heart. The most advanced viable embryo in this series was recovered on the 15th day of gestation, and its morphological features suggest that it was developmentally equivalent to a normal embryo of about 13.5-14 days p.c.

scholarly journals Unequal distribution of 16S mtrRNA at the 2-cell stage regulates cell lineage allocations in mouse embryos

Reproduction ◽  
2016 ◽  
Vol 151 (4) ◽  
pp. 351-367 ◽  
Author(s):  
Zhuxia Zheng ◽  
Hongmei Li ◽  
Qinfen Zhang ◽  
Lele Yang ◽  
Huayu Qi
Keyword(s):  
Cell Fate ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Cell Lineage ◽  
Early Embryogenesis ◽  
Embryonic Cells ◽  
Cell Stage ◽  
Unequal Distribution ◽  
Fate Determinants ◽  
Cell Fate Determinants

Cell lineage determination during early embryogenesis has profound effects on adult animal development. Pre-patterning of embryos, such as that of Drosophila and Caenorhabditis elegans, is driven by asymmetrically localized maternal or zygotic factors, including mRNA species and RNA binding proteins. However, it is not clear how mammalian early embryogenesis is regulated and what the early cell fate determinants are. Here we show that, in mouse, mitochondrial ribosomal RNAs (mtrRNAs) are differentially distributed between 2-cell sister blastomeres. This distribution pattern is not related to the overall quantity or activity of mitochondria which appears equal between 2-cell sister blastomeres. Like in lower species, 16S mtrRNA is found to localize in the cytoplasm outside of mitochondria in mouse 2-cell embryos. Alterations of 16S mtrRNA levels in one of the 2-cell sister blastomere via microinjection of either sense or anti-sense RNAs drive its progeny into different cell lineages in blastocyst. These results indicate that mtrRNAs are differentially distributed among embryonic cells at the beginning of embryogenesis in mouse and they are functionally involved in the regulation of cell lineage allocations in blastocyst, suggesting an underlying molecular mechanism that regulates pre-implantation embryogenesis in mouse.

The effect of dual inhibition of Ras–MEK–ERK and GSK3β pathways on development of in vitro cultured rabbit embryos

Zygote ◽  
2020 ◽  
Vol 28 (3) ◽  
pp. 183-190 ◽  
Author(s):  
Babett Bontovics ◽  
Pouneh Maraghechi ◽  
Bence Lázár ◽  
Mahek Anand ◽  
Kinga Németh ◽  
...  
Keyword(s):  
Stem Cells ◽  
Activin A ◽  
Mouse Strains ◽  
Suitable Model ◽  
Embryonic Cells ◽  
Cell Stage ◽  
Human Ipscs ◽  
Dual Inhibition ◽  
Rabbit Embryos

SummaryDual inhibition (2i) of Ras–MEK–ERK and GSK3β pathways enables the derivation of embryo stem cells (ESCs) from refractory mouse strains and, for permissive strains, allows ESC derivation with no external protein factor stimuli involvement. In addition, blocking of ERK signalling in 8-cell-stage mouse embryos leads to ablation of GATA4/6 expression in hypoblasts, suggesting fibroblast growth factor (FGF) dependence of hypoblast formation in the mouse. In human, bovine or porcine embryos, the hypoblast remains unaffected or displays slight-to-moderate reduction in cell number. In this study, we demonstrated that segregation of the hypoblast and the epiblast in rabbit embryos is FGF independent and 2i treatment elicits only a limited reinforcement in favour of OCT4-positive epiblast populations against the GATA4-/6-positive hypoblast population. It has been previously shown that TGFβ/Activin A inhibition overcomes the pervasive differentiation and inhomogeneity of rat iPSCs, rat ESCs and human iPSCs while prompting them to acquire naïve properties. However, TGFβ/Activin A inhibition, alone or together with Rho-associated, coiled-coil containing protein kinase (ROCK) inhibition, was not compatible with the viability of rabbit embryos according to the ultrastructural analysis of preimplantation rabbit embryos by electron microscopy. In rabbit models ovulation upon mating allows the precise timing of progression of the pregnancy. It produces several embryos of the desired stage in one pregnancy and a relatively short gestation period, making the rabbit embryo a suitable model to discover the cellular functions and mechanisms of maintenance of pluripotency in embryonic cells and the embryo-derived stem cells of other mammals.

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