Search results for "Embryonic Structures"
showing 10 items of 623 documents
An acid extract from dissociation medium of sea urchin embryos, induces mesenchyme differentiation
1992
Abstract When material extracted by 1 M acetic acid from the dissociation medium of sea urchin embryos is added at low concentrations to isolated primary mesenchyme cells, it induces skeletogenesis. The same material added to dissociated blastula cells, or to embryos at the blastula stage, stimulates skeleton formation and pigment cell differentiation. On dissociated cells, it also increases cell reaggregation, thymidine incorporation and survival. On embryos, it induces exogastrulation and appearence of extraembryonic pigment cells. The activity of the extract is resistant to raised temperatures and partially to tryptic digestion but is abolished by trypsin treatment followed by heating. T…
The p21-activated kinase Mbt is a component of the apical protein complex in central brain neuroblasts and controls cell proliferation
2013
The final size of the central nervous system is determined by precisely controlled generation, proliferation and death of neural stem cells. We show here that the Drosophila PAK protein Mushroom bodies tiny (Mbt) is expressed in central brain progenitor cells (neuroblasts) and becomes enriched to the apical cortex of neuroblasts in a cell cycle- and Cdc42-dependent manner. Using mushroom body neuroblasts as a model system, we demonstrate that in the absence of Mbt function, neuroblasts and their progeny are correctly specified and are able to generate different neuron subclasses as in the wild type, but are impaired in their proliferation activity throughout development. In general, loss of…
The RNA-binding protein ELAV regulates Hox RNA processing, expression and function within the Drosophila nervous system
2014
The regulated head-to-tail expression of Hox genes provides a coordinate system for the activation of specific programmes of cell differentiation according to axial level. Recent work indicates that Hox expression can be regulated via RNA processing but the underlying mechanisms and biological significance of this form of regulation remain poorly understood. Here we explore these issues within the developing Drosophila central nervous system (CNS). We show that the pan-neural RNA-binding protein (RBP) ELAV (Hu antigen) regulates the RNA processing patterns of the Hox gene Ultrabithorax (Ubx) within the embryonic CNS. Using a combination of biochemical, genetic and imaging approaches we demo…
Constitutive Promoter Occupancy by the MBF-1 Activator and Chromatin Modification of the Developmental Regulated Sea Urchin α-H2A Histone Gene
2007
The tandemly repeated sea urchin alpha-histone genes are developmentally regulated. These genes are transcribed up to the early blastula stage and permanently silenced as the embryos approach gastrulation. As previously described, expression of the alpha-H2A gene depends on the binding of the MBF-1 activator to the 5' enhancer, while down-regulation relies on the functional interaction between the 3' sns 5 insulator and the GA repeats located upstream of the enhancer. As persistent MBF-1 binding and enhancer activity are detected in gastrula embryos, we have studied the molecular mechanisms that prevent the bound MBF-1 from trans-activating the H2A promoter at this stage of development. Her…
Disruption of apical-basal polarity of human embryonic stem cells enhances hematoendothelial differentiation
2007
Abstract During murine development, the formation of tight junctions and acquisition of polarity are associated with allocation of the blastomeres on the outer surface of the embryo to the trophoblast lineage, whereas the absence of polarization directs cells to the inner cell mass. Here, we report the results of ultrastructural analyses that suggest a similar link between polarization and cell fate in human embryos. In contrast, the five human embryonic stem cell (hESC) lines displayed apical-basal, epithelial-type polarity with electron-dense tight junctions, apical microvilli, and asymmetric distribution of organelles. Consistent with these findings, molecules that are components of tigh…
Defining the genomic signature of totipotency and pluripotency during early human development.
2013
The genetic mechanisms governing human pre-implantation embryo development and the in vitro counterparts, human embryonic stem cells (hESCs), still remain incomplete. Previous global genome studies demonstrated that totipotent blastomeres from day-3 human embryos and pluripotent inner cell masses (ICMs) from blastocysts, display unique and differing transcriptomes. Nevertheless, comparative gene expression analysis has revealed that no significant differences exist between hESCs derived from blastomeres versus those obtained from ICMs, suggesting that pluripotent hESCs involve a new developmental progression. To understand early human stages evolution, we developed an undifferentiation netw…
Human exome and mouse embryonic expression data implicate ZFHX3, TRPS1, and CHD7 in human esophageal atresia
2020
Introduction Esophageal atresia with or without tracheoesophageal fistula (EA/TEF) occurs approximately 1 in 3.500 live births representing the most common malformation of the upper digestive tract. Only half a century ago, EA/TEF was fatal among affected newborns suggesting that the steady birth prevalence might in parts be due to mutational de novo events in genes involved in foregut development. Methods To identify mutational de novo events in EA/TEF patients, we surveyed the exome of 30 case-parent trios. Identified and confirmed de novo variants were prioritized using in silico prediction tools. To investigate the embryonic role of genes harboring prioritized de novo variants we perfor…
Highly restricted expression at the ectoderm–endoderm boundary of PIHbox 9, a sea urchin homeobox gene related to the human HB9 gene
1998
Abstract Characterisation of a sea urchin (P. lividus) homeobox gene PIHbox 9 is reported. The homeodomain of PIHbox9 is 95% identical to the homeodomain of the human HB9 gene, indicating that the two genes are highly related. Temporal expression analysis during sea urchin embryogenesis showed an absence of transcripts at early cleavage stages. At late gastrula stage, transcripts were barely detectable and reached the highest abundance at prism/early pluteus stages. By whole mount in situ hybridisation we observed a highly restricted expression in a few cells of the ectoderm–endoderm boundary of embryos at the prism stage. At pluteus stages, expression of PIHbox 9 was confined around the an…
A novel model of human implantation: 3D endometrium-like culture system to study attachment of human trophoblast (Jar) cell spheroids.
2011
There is an urgent need to develop optimized experimental models to examine human implantation. These studies aimed to (i) establish a human endometrium-like three-dimensional (3D) culture system, and (ii) examine the attachment of trophoblast-like Jar spher- oids to the culture. In the present work, 3D endometrial cultures were constructed with fibrin-agarose as matrix scaffold, and using epithelial and stromal cells from both human primary cultures and established cell lines. An attachment assay between trophoblast cells and the 3D culture was developed. Epithelial cells (cytokeratin + ) concentrated on top of the matrix forming a monolayer, and stromal cells (vimentin + ) resided within …
Sonographic Prognostic Factors in Prenatal Diagnosis of SCT
2003
<i>Objective:</i> A subset of fetuses with sacrococcygeal teratomas (SCT) develops hydrops caused by high-output heart failure. Identification of fetuses at risk for hydrops is important because surgical intervention may reverse the pathophysiology of the disease. The aim of this study was to evaluate sonographic prognostic factors regarding tumor morphology and vascularity associated with the development of hydrops in utero. <i>Methods:</i> Over a 10-year period, we identified 7 fetuses with SCT diagnosed antenatally and managed at the University of Mainz. We retrospectively reviewed the charts of mothers and infants and recorded data on prenatal diagnosis, tumor si…