Search results for "sea urchin."
showing 10 items of 317 documents
Sea urchin HSF activity in vitro and in transgenic embryos.
1997
Evidence is provided for the presence at the physiological temperature of 20 degrees C of a heat shock transcriptor factor, HSF, in the nuclei of P.lividus embryos. This HSF is able to specifically bind in vitro the heat shock element, HSE, of the promoter of the hsp70 gene i.v., as suggested by DNA-protein binding reactions and DNAse I protection assays. Upon heat-shock, at the temperature of 31 degrees C, its ability to bind the HSE units becomes much higher. The HSF activated by heat-shock drives in vivo the transcription of the beta-galactosidase reporter gene in transgenic sea urchin gastrulae. An ATF-like transcription factor, widely described in other organisms but not at all in sea …
EGFR signalling is required for Paracentrotus lividus endomesoderm specification
2008
The EGFR pathway is critical for cell fate specification throughout the development of several organisms. Here we identified in sea urchin an EGFR-related antigen maternally expressed and showing a dynamic pattern of localization during development. To investigate the role played by the EGFR in Paracentrotus lividus development we blocked its activity by using the EGFR kinase inhibitor AG1478. This treatment produces decrease of EGFR phosphorylation, and embryos with various defects especially in the endomesoderm territory until to obtain an animalized phenotype. These effects are rescued by the addition of TGF-alpha, an EGFR ligand. The role played by EGFR-like along the animal/vegetal axi…
In silico characterization of the neural alpha tubulin gene promoter of the sea urchin embryo Paracentrotus lividus by phylogenetic footprinting
2011
During Paracentrotus lividus sea urchin embryo development one alpha and one beta tubulin genes are expressed specifically in the neural cells and they are early end output of the gene regulatory network that specifies the neural commitment. In this paper we have used a comparative genomics approach to identify con- served regulatory elements in the P. lividus neural alpha tubulin gene. To this purpose, we have first isolated a genomic clone containing the entire gene plus 4.5 Kb of 5 0 upstream sequences. Then, we have shown by gene transfer experiments that its non-coding region drives the spatio- temporal gene expression corresponding substantially to that of the endogenous gene. In addi…
Ectopic hbox12 Expression Evoked by Histone Deacetylase Inhibition Disrupts Axial Specification of the Sea Urchin Embryo
2015
Dorsal/ventral patterning of the sea urchin embryo depends upon the establishment of a Nodal-expressing ventral organizer. Recently, we showed that spatial positioning of this organizer relies on the dorsal-specific transcription of the Hbox12 repressor. Building on these findings, we determined the influence of the epigenetic milieu on the expression of hbox12 and nodal genes. We find that Trichostatin-A, a potent and selective histone-deacetylases inhibitor, induces histone hyperacetylation in hbox12 chromatin, evoking broad ectopic expression of the gene. Transcription of nodal concomitantly drops, prejudicing dorsal/ventral polarity of the resulting larvae. Remarkably, impairing hbox12 …
Toxicity of vanadium during development of sea urchin embryos: bioaccumulation, calcium depletion, ERK modulation and cell-selective apoptosis
2022
Vanadium toxicology is a topic of considerable importance as this metal is widely used in industrial and biomedical fields. However, it represents a potential emerging environmental pollutant because wastewater treatment plants do not adequately remove metal compounds that are subsequently released into the environment. Vanadium applications are limited due to its toxicity, so it is urgent to define this aspect. This metal is associated with sea urchin embryo toxicity as it perturbs embryogenesis and skeletogenesis, triggering several stress responses. Here we investigated its bioaccumulation and the correlation with cellular and molecular developmental pathways. We used cytotoxic concentra…
EFFECT OF THE IMPase INHIBITOR L690,330 ON SEA URCHIN DEVELOPMENT
1998
Abstract A variety of concentrations of the IMPase inhibitor L690,330 were added to sea urchin embryos. Immediate arrest of development was obtained for concentrations from 7.5 m m on. Concentrations lower than 3.5 m m permitted gastrulation but inhibited skeletogenesis and disturbed elongation along the animal–vegetal axis. The latter results are similar to those obtained by counteracting lithium effect with myoinositol, which are suggested to be due to partial relief of IMPase inhibition.
DNA-methylation dependent regulation of embryo-specific 5S ribosomal DNA cluster transcription in adult tissues of sea urchin Paracentrotus lividus
2013
Abstract We have previously reported a molecular and cytogenetic characterization of three different 5S rDNA clusters in the sea urchin Paracentrotus lividus and recently, demonstrated the presence of high heterogeneity in functional 5S rRNA. In this paper, we show some important distinctive data on 5S rRNA transcription for this organism. Using single strand conformation polymorphism (SSCP) analysis, we demonstrate the existence of two classes of 5S rRNA, one which is embryo-specific and encoded by the smallest (700 bp) cluster and the other which is expressed at every stage and encoded by longer clusters (900 and 950 bp). We also demonstrate that the embryo-specific class of 5S rRNA is ex…
Early asymmetric cues triggering the dorsal/ventral gene regulatory network of the sea urchin embryo
2014
Dorsal/ventral (DV) patterning of the sea urchin embryo relies on a ventrally-localized organizer expressing Nodal, a pivotal regulator of the DV gene regulatory network. However, the inceptive mechanisms imposing the symmetry-breaking are incompletely understood. In Paracentrotus lividus, the Hbox12 homeodomain-containing repressor is expressed by prospective dorsal cells, spatially facing and preceding the onset of nodal transcription. We report that Hbox12 misexpression provokes DV abnormalities, attenuating nodal and nodal-dependent transcription. Reciprocally, impairing hbox12 function disrupts DV polarity by allowing ectopic expression of nodal. Clonal loss-of-function, inflicted by b…
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…
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…