Search results for " Sea urchin Embryo"
showing 10 items of 29 documents
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…
EFFECT OF Γ-AMINOBUTYRRIC ACID (GABA) EXPOSURE ON EMBRYOGENESIS OF PARACENTROTUS LIVIDUS AND IDENTIFICATION OF GABA-RECEPTOR GENES IN SEA URCHINS
2015
Developmental processes are controlled by regulatory genes encoding for transcription factors and signaling molecules. Functional relationships between these genes are described by gene regulatory networks (GRN), models which allow integration of various levels of information. The sea urchin embryo is an experimental model system which offers many advantages for the analysis of GRN. Recently, the GRN that governs the biomineralization of the sea urchin embryonic skeleton has begun to be deciphered. Preliminary evidence suggest that the γ- aminobutyric acid (GABA) signaling pathway is involved in skeletal morphogenesis during development of the sea urchin. GABA is a molecule synthesized by n…
Identification and characterization of PlAlix, the Alix homologue from the Mediterranean sea urchin Paracentrotus lividus.
2013
The sea urchin provides a relatively simple and tractable system for analyzing the early stages of embryo development. Here, we use the sea urchin species, Paracentrotus lividus, to investigate the role of Alix in key stages of embryogenesis, namely the egg fertilization and the first cleavage division. Alix is a multifunctional protein involved in different cellular processes including endocytic membrane trafficking, filamentous (F)-actin remodeling, and cytokinesis. Alix homologues have been identified in different metazoans; in these organisms, Alix is involved in oogenesis and in determination/differentiation events during embryo development. Herein, we describe the identification of th…
Vanadium Modulates Proteolytic Activities and MMP-14-Like Levels during Paracentrotus lividus Embryogenesis
2022
The increasing industrial use of vanadium (V), as well as its recent medical use in various pathologies has intensified its environmental release, making it an emerging pollutant. The sea urchin embryo has long been used to study the effects induced by metals, including V. In this study we used an integrated approach that correlates the biological effects on embryo development with proteolytic activities of gelatinases that could better reflect any metal-induced imbalances. V-exposure caused morphological/morphometric aberrations, mainly concerning the correct distribution of embryonic cells, the development of the skeleton, and the embryo volume. Moreover, V induced a concentration change …
Symmetry Breaking and Establishment of Dorsal/Ventral Polarity in the Early Sea Urchin Embryo
2015
The mechanisms imposing the Dorsal/Ventral (DV) polarity of the early sea urchin embryo consist of a combination of inherited maternal information and inductive interactions among blastomeres. Old and recent studies suggest that a key molecular landmark of DV polarization is the expression of nodal on the future ventral side, in apparent contrast with other metazoan embryos, where nodal is expressed dorsally. A subtle maternally-inherited redox anisotropy, plus some maternal factors such as SoxB1, Univin, and p38-MAPK have been identified as inputs driving the spatially asymmetric transcription of nodal. However, all the mentioned factors are broadly distributed in the embryo as early as no…
Marine Invertebrates as Bioindicators of Heavy Metal Pollution
2014
Atmosphere, earth and water compose the environment. The presence of heavy metals in the environment has grown because of their large employment in some industrial and agricultural activities. Although these metals are terrestrial products, they flow into the sea through effluents and sewage or are directly discharged from industries placed on the seawater front. It should be considered that metals concentrations vary widely according to different seawater latitudes and depths and can be strongly influenced by fresh water discharges from heavily polluted rivers. In this review recent studies on heavy metal pollution in marine ecosystems and their organisms will be presented. Metal speciatio…
Sea urchin embryos exposed to cadmium as an experimental model for studying the relationship between autophagy and apoptosis
2014
The sea urchin embryo is a suitable model that offers an excellent opportunity to investigate different defence strategies activated in stress conditions. We previously showed that cadmium accumulates in a dose- and time-dependent manner into embryonic cells, activating different stress and defence mechanisms, including the synthesis of HSPs and the onset of apoptosis and/or autophagy. In this paper we investigated the functional relationship between autophagy and apoptosis, evaluating apoptosis signals in cadmium-exposed Paracentrotus lividus embryos with inhibited autophagy. We found that the inhibition of autophagy produced the concurrent reduction of apoptosis, suggesting that the two p…
Toxicity induced by Gadolinium ions on sea urchin embryos: comparison among phylogenetically distant species and focus on stress response and skeleto…
2016
Pharmaceuticals are a class of emerging environmental contaminants. Gadolinium (Gd) is a lanthanide metal whose chelates are employed as contrast agents for magnetic resonance imaging, and subsequently released into the aquatic environment. We investigated the effects of exposure to sublethal Gd concentrations on the development of four phylogenetically and geographically distant sea urchin species: two Mediterranean, Paracentrotus lividus and Arbacia lixula, and two from Australia, Heliocidaris tuberculata and Centrostephanus rodgersii. Sensitivity to Gd greatly varied, with EC50 ranging from 56 nM to 132 µM across the four species. Measures of the Gd and Ca content inside embryos showed a…
Enhancer, chromatin insulator, non-coding RNA and α-histone gene expression during embryogenesis of the sea urchin Paracentrotus lividus.
2009
Core promoters and chromatin insulators (ins) may direct a transcriptional enhancer (enh) to prefer a specific promoter in complex genetic loci. Enh and ins flank the sea urchin Paracentrotus lividus α-histone H2A transcription unit in a tandem repeated cluster containing the five histone genes. In vivo competition assays of enh and ins functions reveal that the H2A enh-bound MBF-1 activator participates also in the expression of the H3 gene and that the sns5 ins buffers the downstream H1 promoter from the H2A enh. These results suggest that both the H2A enh and the sns5 ins may account for the diverse accumulation of the linker vs core nucleosomal histones during early development of the s…
Suppression of nodal expression in prospective dorsal cells of the early sea urchin embryo by the hbox12 homeodomain regulator
2014
Dorsal/Ventral (DV) axis formation in the sea urchin embryo depends upon the expression of nodal on the ventral side, which behaves as a DV organizing centre. However, only fuzzy clues are known as to the early symmetry-breaking steps that lead to the positioning of such an organizer. An extremely interesting candidate for this role is the hbox12 homeobox-containing gene. In Paracentrotus lividus, hbox12 expression is antecedent and complementary with respect to that of nodal, being confined in prospective dorsal cells. We show that ectopic expression of Hbox12 provokes DV abnormalities and attenuates nodal as well as nodal-dependent gene transcription. By blastomere transplantation, we als…