Project description:Seawater exposure to the gram negative marine bacterium Vibrio diazotrophicus induces a robust cellular response in sea urchin larvae that includes the migration of pigment cells to the gut epithelium, changes in cell behavior and altered gut morphology (Ho et al., 2016; PMID 27192936). To investigate the transcriptional underpinnings of this response, whole transcriptome sequencing was performed on mRNA isolated from larval samples collected at 0, 6, 12 and 24 hr of exposure to V. diazotrophicus. The morphological simplicity of the sea urchin larva provides a systems-level model for identifying biologically relevant transcriptional state changes in response to dysbiosis in the gut lumen.
Project description:Engineered nanoparticles (ENPs) are increasingly used to generate innovative industrial and medical goods. Because of their broad applications, they form a new class of pollutants with potential eco-toxicological impacts on marine ecosystems. Attempting to evaluate the risk, we investigated the toxicity of Iron and Zinc oxide ENPs on Paracentrotus lividus sea urchin embryos. Sea urchin embryos are sensitive to both ENPs with a much stronger impact of ZnO ENPs. Transcriptome-wide analyses were conducted after exposure to ENPs or the corresponding ions. Only a very limited number of genes are differentially expressed in response to Fe2O3 ENPs or FeCl3. In contrast, both ZnO ENPs and ZnSO4 caused alteration of biological processes with stronger perturbation of gene expression for the ionic form (higher LFC). Comparison of GO term enrichment of the differentially expressed genes indicated that ENP and ions elicited partly different mechanisms, suggesting that a nanoparticule-dependent response was induced. Remarkably, the expression of the metal binding and ROS scavenging Metallothioneins were massively induced by ZnO ENPs and ZnSO4 while ZnO ENPs and ions mainly repressed the transcription regulation processes which control embryo development.
Project description:We identified cis-regulatory elements based on their dynamic chromatin accessibility during the gastrula-larva stages of sea urchin and sea star and studied their evolution in these echinoderm species
Project description:Transcription factor SoxC is required for all neural development in purple sea urchin S. purpuratus embryos. To begin to develop a gene regulatory network for neural development, we used RNA-Seq to compare transcript populations in SoxC knockdown and control embryos.
Project description:Sea urchins are emblematic marine animals with a rich fossil record and represent instrumental models for developmental biology. As echinoderms, sea urchins display several characteristics that set them apart from other deuterostomes such as their highly regulative embryonic development and their unique pentaradial adult body plan. To determine whether these characteristics are linked to particular genomic rearrangement or gene regulatory rewiring, we introduce a chromosome-scale genome assembly for sea urchin Paracentrotus lividus as well as extensive transcriptomic and epigenetic profiling during its embryonic development. We found that sea urchins show opposite modalities of genome evolution as compared to those of vertebrates: they retained ancestral chromosomal linkages that otherwise underwent mixing in vertebrates, while their intrachromosomal gene order has evolved much faster between sea urchin species that split 60 Myr ago than it did in vertebrates. We further assessed the conservation of the cis-regulatory program between sea urchins and chordates and identified conserved modules despite the developmental and body plan differences. We documented regulatory events underlying processes like zygotic genome activation and transition to larval stage in sea urchins. We also identified a burst of gene duplication in the echinoid lineage and showed that some of these expanded genes are involved in organismal novelties, such as Aristotle's lantern, tube feet, or in the specification of lineages through for instance the pmar1 and pop genes. Altogether, our results suggest that gene regulatory networks controlling development can be conserved despite extensive gene order rearrangement.
Project description:Transcription factor SoxC is required for all neural development in purple sea urchin S. purpuratus embryos. To begin to develop a gene regulatory network for neural development, we used RNA-Seq to compare transcript populations in SoxC knockdown and control embryos. SoxC function was knocked down by morpholino oligo injection. RNA from about 1000 embryos were collected for both control and knockdown samples.
Project description:Sea urchins lack proper eye organs but are photosensitive. In this study, we investigate an extraocular photoreceptor cell (PRC) system in developmental stages of the sea urchin Paracentrotus lividus.
Project description:We used CAGE-seq (Capped Analysis of Gene Expression with Sequencing) to profile eRNA expression and enhancer activity during embryogenesis of the sea urchin, Strongylocentrotus purpuratus. We identified >18,000 enhancers that were active during late oogenesis and early development and documented a burst of enhancer activation during cleavage and early blastula stages. Most enhancers were located near gene bodies and eRNA expression levels were highest for elements near core promoters. Transcriptional signals from enhancers generally paralleled the expression levels of likely target genes. Furthermore, enhancers near lineage-specific genes contained signatures of inputs from developmental gene regulatory networks deployed in those lineages. A large fraction (60%) of sea urchin enhancers previously shown to be active in transgenic reporter assays were associated with eRNA expression. Moreover, a large fraction (50%) of a representative subset of enhancers identified by eRNA profiling drove tissue-specific gene expression in isolation when tested by reporter assays. Our findings provide an atlas of developmental enhancers in a model sea urchin and support the utility of eRNA profiling as a tool for enhancer discovery and regulatory biology. The data generated in this study are publicly available at Echinobase (www.echinobase.org).
Project description:Marine bioadhesives have unmatched performances especially in wet environments, being valuable sources of inspiration for industrial and biomedical applications. In sea urchins specialized adhesive organs, called tube feet, mediate adhesion. These are composed by a disc, which produces adhesive and de-adhesive secretions for strong reversible attachment, and a motile stem. After detachment, the secreted adhesive remains bound to the substratum as a footprint. Previous studies showed that sea urchin adhesive is composed of proteins and sugars, but so far only one protein, Nectin, was shown to be over-expressed as a transcript in tube feet discs, suggesting its involvement in sea urchin adhesion. Here we use high-resolution quantitative mass-spectrometry technologies to profile Paracentrotus lividus tube feet differential proteome, comparing protein expression levels in its adhesive part (disc) versus the non-adhesive part (stem). This allowed us to identify 163 highly over-expressed disc proteins and propose the first molecular model of sea urchin reversible adhesion. The secreted adhesive proteome was also analyzed, whereby we found that 70% of its components fall within five protein groups, involved in adhesive exocytosis and protection against microbes. Our data also provides evidence that Nectin is not only highly expressed in tube feet discs but is a component of the adhesive itself, thus constituting the first report of a sea urchin tube foot adhesive protein. These results give us an unprecedented insight on the molecular mechanics underlying sea urchins reversible adhesion, opening new doors to develop new, wet-reliable, reversible, efficient, ecological biomimetic adhesives.