Search results for " skeletogenesis"

Cellular and molecular bases of biomineralization in sea urchin embryos

2013

Sea urchin embryos construct their skeleton following a precise gene-regulated time- and space-dependent programme, in concert with factors promoting cell adhesion and differentiation. The biomineral is deposited in a privileged extracellular space produced by the fused filopodia processes of the primary mesenchyme cells, the only cells producing a set of necessary matrix proteins. More than ten years ago we showed for the first time that signals from ectoderm cells promoted the expression of one of the major skeleton matrix genes by the primary mesenchyme cells. Since then, many of the crucial steps of this complex activation cascade, from ectoderm cells to embryonic spicules, have been el…

Effects of exposure to gadolinium on the development of geographically and phylogenetically distant sea urchins species.

2016

Gadolinium (Gd), a metal of the lanthanide series used as contrast agent for magnetic resonance imaging, is released into the aquatic environment. We investigated the effects of Gd on the development of four sea urchin species: two from Europe, Paracentrotus lividus and Arbacia lixula, and two from Australia, Heliocidaris tuberculata and Centrostephanus rodgersii. Exposure to Gd from fertilization resulted in inhibition or alteration of skeleton growth in the plutei. The similar morphological response to Gd in the four species indicates a similar mechanism underlying abnormal skeletogenesis. Sensitivity to Gd greatly varied, with the EC50 ranging from 56 nM to 132 μM across the four species…

CELLULAR AND MOLECULAR MECHANISMS ACTIVATED IN SEA URCHIN EMBRYOS EXPOSED TO GADOLINIUM, EMERGING ENVIRONMENTAL CONTAMINANT

Localized expression of Strim1, a novel member of the TRIM-containing family, guides the skeletal morphogenetic program of the sea urchin embryo

2011

The building of the skeleton in the indirect developing sea urchin embryo is a complex morphogenetic process that is executed by the Primary Mesenchyme Cells or PMCs (Ettensohn et al, 1997; Wilt 2002). It is well known that the PMCs acquire most of the positional and temporal information from the overlying ectoderm for skeletal initiation and growth (Armstrong 1993; Cavalieri et al, 2003; Röttinger et al, 2008). In this study, we analyze the function of a novel gene, encoding for a tripartite motif-containing (TRIM) protein denoted strim1, that adds up to the list of genes constituting the epithelial-mesenchymal signaling network. We show that strim1 is expressed in ectoderm regions adjacen…

A study on the effect of the inhibition of polyadenylylation on the production of giant cytoplasmic RNA in sea urchin embryos.

1975

It is suggested that inhibition of RNA polyadenylylation in sea urchin mesenchyme blastulae causes a disturbance of the transport of all the size classes of newly synthesized RNA from the nucleus to the cytoplasm.

Gadolinium perturbs expression of skeletogenic genes, calcium uptake and larval development in phylogenetically distant sea urchin species

2018

Chelates of Gadolinium (Gd), a lanthanide metal, are employed as contrast agents for magnetic resonance imaging and are released into the aquatic environment where they are an emerging contaminant. We studied the effects of environmentally relevant Gd concentrations on the development of two phylogenetically and geographically distant sea urchin species: the Mediterranean Paracentrotus lividus and the Australian Heliocidaris tuberculata. We found a general delay of embryo development at 24 h post-fertilization, and a strong inhibition of skeleton growth at 48 h. Total Gd and Ca content in the larvae showed a time- and concentration-dependent increase in Gd, in parallel with a reduction in C…

Regulatory sequences driving expression of the sea urchin Otp homeobox gene in oral ectoderm cells.

2005

Abstract PlOtp (Orthopedia), a homeodomain-containing transcription factor, has been recently characterized as a key regulator of the morphogenesis of the skeletal system in the embryo of the sea urchin Paracentrotus lividus . Otp acts as a positive regulator in a subset of oral ectodermal cells which transmit short-range signals to the underlying primary mesenchyme cells where skeletal synthesis is initiated. To shed some light on the molecular mechanisms involved in such a process, we begun a functional analysis of the cis -regulatory sequences of the Otp gene. Congruent with the spatial expression profile of the endogenous Otp gene, we found that while a DNA region from −494 to +358 is s…

p38 MAPK activation is required for Paracentrotus lividus skeletogenesis

2008

We investigated the p38 MAPK role during sea urchin, Paracentrotus lividus, development. We found that at the morula stage, before the onset of skeletogenesis, p38 MAPK shows a peak of activity, and we tested whether p38 MAPK activity has any effect on skeletogenesis. By immunohistochemistry on whole-mount embryos we show the preferential localization of the active p38 form both in the presumptive PMCs and bilateral spiculo- genesis centers in control embryos, and in the radialized supernumerary spiculogenesis centers induced by NiCl2 treatment. By using SB203580, a p38 MAPK specific inhibitor, we show that p38 activity is required both for the initial triradiate spicule rudiments formation…

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…