scholarly journals Studying early embryogenesis in the flatwormMaritigrella crozieriindicates a unique modification of the spiral cleavage program in polyclad flatworms

2019 ◽  
Author(s):  
Johannes Girstmair ◽  
Maximilian J. Telford
Keyword(s):  
Early Embryogenesis ◽  
Cleavage Pattern ◽  
Spiral Cleavage ◽  
Cell Stage ◽  
3D Reconstructions ◽  
Adult Body ◽  
Polyclad Flatworms ◽  
Early Developmental ◽  
Detailed Picture ◽  
Canonical Pattern

AbstractBackgroundSpiral cleavage is a conserved early developmental mode found in several phyla of Lophotrochozoans with highly diverse adult body plans. While the cleavage pattern has clearly been broadly conserved, it has also undergone many modifications in various taxa. The precise mechanisms of how different adaptations have altered the ancestral spiral cleavage pattern is an important ongoing evolutionary question and adequately answering this question requires obtaining a broad developmental knowledge of different spirally cleaving taxa.In flatworms (Platyhelminthes), the spiral cleavage program has been lost or severely modified in most taxa. Polyclad flatworms, however, have retained the pattern up to the 32-cell stage. Here we study early embryogenesis of the cotylean polyclad flatwormMaritigrella crozierito investigate how closely this species follows the canonical spiral cleavage pattern and to discover any potential deviations from it.ResultsUsing live imaging recordings and 3D reconstructions of embryos, we give a detailed picture of the events that occur during spiral cleavage inM. crozieri. We suggest, contrary to previous observations, that the 4-cell stage is a product of unequal cleavages. We show that that the formation of third and fourth micromere quartets are accompanied by strong blebbing events; blebbing also accompanies the formation of micromere 4d. We find an important deviation from the canonical pattern of cleavages with clear evidence that micromere 4d follows an atypical cleavage pattern, so far exclusively found in polyclad flatworms.ConclusionsOur findings highlight that early development inM. crozierideviates in several important aspects from the canonical spiral cleavage pattern. We suggest that some of our observations extend to polyclad flatworms in general as they have been described in both suborders of the Polycladida, the Cotylea and Acotylea.

scholarly journals Simultaneous deletion of the methylcytosine oxidases Tet1 and Tet3 increases transcriptome variability in early embryogenesis

2015 ◽  
Vol 112 (31) ◽  
pp. E4236-E4245 ◽  
Author(s):  
Jinsuk Kang ◽  
Matthias Lienhard ◽  
William A. Pastor ◽  
Ashu Chawla ◽  
Mark Novotny ◽  
...  
Keyword(s):  
Single Cells ◽  
Cholesterol Biosynthesis ◽  
Early Embryogenesis ◽  
Dna Demethylation ◽  
Cell Stage ◽  
Tet Proteins ◽  
Genes Encoding ◽  
Variable Gene ◽  
Intracellular Pathways ◽  
Tet Enzymes

Dioxygenases of the TET (Ten-Eleven Translocation) family produce oxidized methylcytosines, intermediates in DNA demethylation, as well as new epigenetic marks. Here we show data suggesting that TET proteins maintain the consistency of gene transcription. Embryos lacking Tet1 and Tet3 (Tet1/3 DKO) displayed a strong loss of 5-hydroxymethylcytosine (5hmC) and a concurrent increase in 5-methylcytosine (5mC) at the eight-cell stage. Single cells from eight-cell embryos and individual embryonic day 3.5 blastocysts showed unexpectedly variable gene expression compared with controls, and this variability correlated in blastocysts with variably increased 5mC/5hmC in gene bodies and repetitive elements. Despite the variability, genes encoding regulators of cholesterol biosynthesis were reproducibly down-regulated in Tet1/3 DKO blastocysts, resulting in a characteristic phenotype of holoprosencephaly in the few embryos that survived to later stages. Thus, TET enzymes and DNA cytosine modifications could directly or indirectly modulate transcriptional noise, resulting in the selective susceptibility of certain intracellular pathways to regulation by TET proteins.

Oral Character and Attitudes and Behavior Related to Food and Eating

1988 ◽  
Vol 63 (1) ◽  
pp. 15-18 ◽  
Author(s):  
Jon K. Mills ◽  
Jean Cunningham
Keyword(s):  
Body Weight ◽  
Developmental Stages ◽  
Female College Students ◽  
Adult Personality ◽  
Adult Body ◽  
Adult Body Weight ◽  
Projective Measure ◽  
And Behavior ◽  
Attitudes And Behavior ◽  
Early Developmental

Freudian theory predicts that adult personality characteristics and behavior will reflect unresolved conflicts from early developmental stages. In this study, a card from the Blum's Blacky test was used as a projective measure of oral conflict with 35 male and 61 female college students. The presence of such conflict was significantly associated with deviations from norms for body weight, greater variability in adult body weight, rating food as important, and eating more frequently. However, ratings of preoccupation with food were not significantly related to scores for oral conflict. These findings support predictions from psychoanalytic theory and also point to the continued usefulness of the Blacky test in psychoanalytic research.

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.

scholarly journals SEBOX Is Essential for Early Embryogenesis at the Two-Cell Stage in the Mouse1

2008 ◽  
Vol 79 (6) ◽  
pp. 1192-1201 ◽  
Author(s):  
Kyeoung-Hwa Kim ◽  
Eun-Young Kim ◽  
Kyung-Ah Lee
Keyword(s):  
Early Embryogenesis ◽  
Cell Stage

Relationships between timing of syngamy, female age and implantation potential in human invitro-fertilised oocytes

2007 ◽  
Vol 19 (3) ◽  
pp. 482 ◽  
Author(s):  
Celine Lawler ◽  
H. W. Gordon Baker ◽  
David H. Edgar
Keyword(s):  
Multiple Logistic Regression Analysis ◽  
Implantation Rate ◽  
Subsequent Development ◽  
Multiple Logistic Regression ◽  
Predictors Of Outcome ◽  
Cell Stage ◽  
Female Age ◽  
Early Entry ◽  
Early Developmental

Although early developmental markers are frequently used to select embryos for transfer in human assisted reproduction, their value as independent predictors of outcome is often unclear. In this study, the value of using early syngamy and first cleavage as predictors of implantation potential of Day 2 embryos was investigated by examining their interrelationships with subsequent development, female age and implantation. Implantation rates were higher when syngamy occurred before 23–24 h post insemination even when all embryos analysed were transferred 42 h post insemination at the 4-cell stage (25.8 v. 11.9% for the later syngamy group; P < 0.01). Although there was a significant (r = 0.682; P < 0.001) relationship between earlier entry into syngamy and female age, earlier syngamy was still associated with a significantly higher implantation rate in Day 2 embryos with four blastomeres in women under 36 years of age (31.4 v. 15.4% for the later syngamy group; P < 0.05). The ability of timing of syngamy to predict implantation independent of other variables was confirmed by multiple logistic regression analysis. Although related to both subsequent embryo development and female age, early entry into syngamy is a predictor of implantation potential independent of both correlates in human Day 2 in vitro-fertilised embryos.

Modified Spiral Cleavage: The Duet Cleavage Pattern and Early Blastomer Fates in the Acoel Turbellarian Neochildia fusca

1996 ◽  
Vol 191 (2) ◽  
pp. 285-286 ◽  
Author(s):  
B. C. Boyer ◽  
J. Q. Henry ◽  
M. Q. Martindale
Keyword(s):  
Cleavage Pattern ◽  
Spiral Cleavage

83 STAGE-SPECIFIC PROTEOME SIGNATURES IN EARLY BOVINE EMBRYO DEVELOPMENT

2015 ◽  
Vol 27 (1) ◽  
pp. 134
Author(s):  
D. R. Deutsch ◽  
T. Fröhlich ◽  
K. A. Otte ◽  
A. Beck ◽  
F. A. Habermann ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Principal Component ◽  
Proteome Analysis ◽  
Early Embryogenesis ◽  
Bovine Embryo ◽  
Protein Abundance ◽  
Absolute Quantitation ◽  
Cell Stage ◽  
Proteolytic Activation

Development of early embryonic stages before activation of the embryonic genome depends on sufficiently stored products of the maternal genome and adequate activation, deactivation, and relocation of proteins. To establish protein function, several posttranslational events (e.g. proteolytic activation, phosphorylation, or secretion) are frequently essential and thereby prevent prediction of protein abundance from transcript abundance. Consequently, proteomic studies are indispensable to characterise the molecular processes governing early embryonic development and to establish corresponding regulatory networks. Here, we present a quantitative proteome analysis of bovine zygotes and embryos at the 2-cell and 4-cell stage. Cumulus-oocyte complexes (COC) were prepared from bovine ovaries obtained from a local abattoir and selected for a compact layer of cumulus cells. In vitro maturation, fertilization, and embryo production were performed according to standard procedures. For quantitative isobaric tags for relative and absolute quantitation (iTRAQ)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, protein from batches of 50 MII oocytes (serving as a reference), zygotes, 2-cell and 4-cell stage embryos, respectively, was extracted. Quantitative proteome analysis of iTRAQ-labelled tryptic peptides was performed on an Orbitrap XL instrument (Thermo Fisher, Waltham, MA, USA) coupled to an Eksigent nano-liquid chromatography system (AB Sciex, Framingham, MA, USA). The tandem MS data were analysed by MASCOT and filtered for a false discovery rate (FDR) of <1%. Quantification of iTRAQ signals was accomplished with the Q+ module of the Scaffold software (Proteome Software Inc., Portland, OR, USA). t-Tests, ANOVA and principal component analysis (PCA) analysis were performed using R (R Core Development Team, Vienna, Austria). From 4 biological replicates, 1072 proteins were identified and quantified. Eighty-seven differed significantly in abundance between the 4 stages (log2 fold change ≥ |0.6|, P ≤ 0.05). The proteomes of 2-cell and 4-cell embryos differed most from the reference MII oocyte, and a considerable fraction of proteins continuously increases in abundance during the stages analysed. Bioinformatic analysis of abundance altered proteins provided evidence that the proteins RPS14 and HNRNPK involved in the p53 pathway play a major role during early development, as well as proteins of the lipid metabolism, in particular APOA1. Furthermore, a group of proteins (e.g. SPTBN1, PPP1CC, RABGAP1, STMN1, and WEE2) is engaged in mitosis. In addition, we detected relevant differences between transcript and protein abundance levels; for example, for WEE2. In conclusion, this study identified and quantified numerous proteins important for early embryogenesis so far not described in the mammalian system, and contributed protein profiles for key players previously described. Our results highlight the importance of innovative proteomic tools and workflows to complement transcriptome data of early embryogenesis.

scholarly journals Zebrafish Polycomb repressive complex-2 critical roles are largely Ezh2- over Ezh1-driven and concentrate during early embryogenesis

2021 ◽  
Author(s):  
Gabriel A. Yette ◽  
Scott Stewart ◽  
Kryn Stankunas
Keyword(s):  
Cell Fate ◽  
Transcriptional Repression ◽  
Axial Skeleton ◽  
Early Embryogenesis ◽  
Loss Of Function ◽  
Allelic Series ◽  
Polycomb Repressive Complex ◽  
Genetic Studies ◽  
Polycomb Repressive Complex 2 ◽  
Early Developmental

ABSTRACTPolycomb repressive complex-2 (PRC2) methylation of histone H3 lysine-27 (H3K27me) is associated with stable transcriptional repression. PRC2 famously silences Hox genes to maintain anterior-posterior segment identities but also enables early cell fate specification, restrains progenitor cell differentiation, and canalizes cell identities. Zebrafish PRC2 genetic studies have focused on ezh2, which, with its paralog ezh1, encodes the H3K27 methyltransferase component. ezh2 loss-of-function mutants reinforce essential vertebrate PRC2 functions during early embryogenesis albeit with limited contributions to body plan establishment. However, redundancy with ezh1 and the lethality of maternal-zygotic homozygous ezh2 nulls could obscure additional early developmental and organogenesis roles of PRC2. Here, we combine new and existing zebrafish ezh1 and ezh2 alleles to show collective maternal/zygotic ezh2 exclusively provides earliest embryonic PRC2 H3K27me3 activity. Zygotic ezh1, which becomes progressively expressed as ezh2 levels dissipate, has minor redundant and noncompensatory larval roles but itself is not required for viability or fertility. Zygotic Ezh2/PRC2 promotes correct craniofacial bone shape and size by maintaining proliferative pre-osteoblast pools. An ezh2 allelic series including disrupted maternal ezh2 uncovers axial skeleton homeotic transformations and pleiotropic organogenesis defects. Further, once past a critical early window, we show zebrafish can develop near normally with minimal bulk H3K27me3. Our results suggest Ezh2-containing PRC2 stabilizes rather than instructs early developmental decisions while broadly contributing to organ size and embellishment.

scholarly journals Physical constraints on early blastomere packings

2021 ◽  
Vol 17 (1) ◽  
pp. e1007994
Author(s):  
James Giammona ◽  
Otger Campàs
Keyword(s):  
Cell Division ◽  
Developmental Stages ◽  
Physical Parameters ◽  
Cell Stage ◽  
Physical Constraints ◽  
Equilibrium Dynamics ◽  
Deformable Particles ◽  
Early Embryos ◽  
Early Developmental Stages ◽  
Early Developmental

At very early embryonic stages, when embryos are composed of just a few cells, establishing the correct packing arrangements (contacts) between cells is essential for the proper development of the organism. As early as the 4-cell stage, the observed cellular packings in different species are distinct and, in many cases, differ from the equilibrium packings expected for simple adherent and deformable particles. It is unclear what are the specific roles that different physical parameters, such as the forces between blastomeres, their division times, orientation of cell division and embryonic confinement, play in the control of these packing configurations. Here we simulate the non-equilibrium dynamics of cells in early embryos and systematically study how these different parameters affect embryonic packings at the 4-cell stage. In the absence of embryo confinement, we find that cellular packings are not robust, with multiple packing configurations simultaneously possible and very sensitive to parameter changes. Our results indicate that the geometry of the embryo confinement determines the packing configurations at the 4-cell stage, removing degeneracy in the possible packing configurations and overriding division rules in most cases. Overall, these results indicate that physical confinement of the embryo is essential to robustly specify proper cellular arrangements at very early developmental stages.

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