The Buds of Oscarella lobularis (Porifera, Homoscleromorpha): A New Convenient Model for Sponge Cell and Evolutionary Developmental Biology.

The comparative study of the four non-bilaterian phyla (Cnidaria, Placozoa, Ctenophora, and Porifera) provides insights into the origin of bilaterian traits. To complete our knowledge of the cell biology and development of these animals, additional non-bilaterian models are needed. Given the developmental, histological, ecological, and genomic differences between the four sponge classes (Demospongiae, Calcarea, Homoscleromorpha, and Hexactinellida), we have been developing the Oscarella lobularis (Porifera, class Homoscleromorpha) model over the past 15 years.

Methylmercury exposure of the sponge O. lobularis induces strong tissue and cell defects.

Mediterranean marine biota suffers from various anthropogenic threats. Among them, pollutants such as mercury (Hg) represent important environmental issues that are exacerbated by bioaccumulation and bioamplification along food webs via its organic form, monomethylmercury (MMHg). To date, very little is known regarding the impact of mercury on Porifera and the few available studies have been exclusively focused on Demospongiae.

Hyper-accumulation of vanadium in animals: Two sponges compete with urochordates.

Vanadium (V) concentrations in organisms are usually very low. To date, among animals, only some urochordate and annelid species contain very high levels of V in their tissues. A new case of hyper-accumulation of V in a distinct animal phylum (Porifera), namely, the two homoscleromorph sponge species Oscarella lobularis and O.

The compact genome of the sponge Oopsacas minuta (Hexactinellida) is lacking key metazoan core genes.

Background: Explaining the emergence of the hallmarks of bilaterians is a central focus of evolutionary developmental biology-evodevo-and evolutionary genomics. For this purpose, we must both expand and also refine our knowledge of non-bilaterian genomes, especially by studying early branching animals, in particular those in the metazoan phylum Porifera.

Results: We present a comprehensive analysis of the first whole genome of a glass sponge, Oopsacas minuta, a member of the Hexactinellida.

The sponge Oscarella lobularis (Porifera, Homoscleromorpha) as a suitable biomonitor of metallic contamination in Mediterranean coastal ecosystems.

The biomonitoring of metallic contamination in marine ecosystems is often focused on animal species of commercial interest and in lesser extent on non-model marine invertebrates. The aim of this study was to compare the metal concentrations (Li, Al, Ti, Cr, Fe, Ni, Cu, Zn, As, Ag, Cd, Hg, Pb) in seven marine sponges with a particular interest in the homoscleromorph sponge Oscarella lobularis at different sites of the Bay of Marseille, France. Inter-species variabilities suggest that the seven sponge species studied accumulate metals differently.

Evolution of mechanisms controlling epithelial morphogenesis across animals: new insights from dissociation-reaggregation experiments in the sponge Oscarella lobularis.

Background: The ancestral presence of epithelia in Metazoa is no longer debated. Porifera seem to be one of the best candidates to be the sister group to all other Metazoa. This makes them a key taxon to explore cell-adhesion evolution on animals.

In Situ Hybridization Techniques in the Homoscleromorph Sponge Oscarella lobularis.

The Porifera are one of the best candidates as the sister group to all other metazoans. Studies on this phylum are therefore expected to shed light on the origin and early evolution of key animal features. Transcriptomic or genomic data acquired during the last 10 years have highlighted the conservation of most of the main genes and pathways involved in the development of the other metazoans.

Staining and Tracking Methods for Studying Sponge Cell Dynamics.

To better understand the origin of animal cell types, body plans, and other morphological features, further biological knowledge and understanding are needed from non-bilaterian phyla, namely, Placozoa, Ctenophora, and Porifera. This chapter describes recent cell staining approaches that have been developed in three phylogenetically distinct sponge species-the homoscleromorph Oscarella lobularis, and the demosponges Amphimedon queenslandica and Lycopodina hypogea-to enable analyses of cell death, proliferation, and migration. These methods allow for a more detailed understanding of cellular behaviors and fates, and morphogenetic processes in poriferans, building on current knowledge of sponge cell biology that relies chiefly on classical (static) histological observations.

Understanding Animal Evolution: The Added Value of Sponge Transcriptomics and Genomics: The disconnect between gene content and body plan evolution.

Sponges are important but often-neglected organisms. The absence of classical animal traits (nerves, digestive tract, and muscles) makes sponges challenging for non-specialists to work with and has delayed getting high quality genomic data compared to other invertebrates. Yet analyses of sponge genomes and transcriptomes currently available have radically changed our understanding of animal evolution.

New genomic data and analyses challenge the traditional vision of animal epithelium evolution.

Background: The emergence of epithelia was the foundation of metazoan expansion. Epithelial tissues are a hallmark of metazoans deeply rooted in the evolution of their complex developmental morphogenesis processes. However, studies on the epithelial features of non-bilaterians are still sparse and it remains unclear whether the last common metazoan ancestor possessed a fully functional epithelial toolkit or if it was acquired later during metazoan evolution.

Animal multicellularity and polarity without Wnt signaling.

Acquisition of multicellularity is a central event in the evolution of Eukaryota. Strikingly, animal multicellularity coincides with the emergence of three intercellular communication pathways - Notch, TGF-β and Wnt - all considered as hallmarks of metazoan development. By investigating Oopsacas minuta and Aphrocallistes vastus, we show here that the emergence of a syncytium and plugged junctions in glass sponges coincides with the loss of essential components of the Wnt signaling (i.

The Conservation of the Germline Multipotency Program, from Sponges to Vertebrates: A Stepping Stone to Understanding the Somatic and Germline Origins.

The germline definition in metazoans was first based on few bilaterian models. As a result, gene function interpretations were often based on phenotypes observed in those models and led to the definition of a set of genes, considered as specific of the germline, named the "germline core". However, some of these genes were shown to also be involved in somatic stem cells, thus leading to the notion of germline multipotency program (GMP).

Retracing the path of planar cell polarity.

Background: The Planar Cell Polarity pathway (PCP) has been described as the main feature involved in patterning cell orientation in bilaterian tissues. Recently, a similar phenomenon was revealed in cnidarians, in which the inhibition of this pathway results in the absence of cilia orientation in larvae, consequently proving the functional conservation of PCP signaling between Cnidaria and Bilateria. Nevertheless, despite the growing accumulation of databases concerning basal lineages of metazoans, very few information concerning the existence of PCP components have been gathered outside of Bilateria and Cnidaria.

ROCK inhibition abolishes the establishment of the aquiferous system in Ephydatia muelleri (Porifera, Demospongiae).

The Rho associated coiled-coil protein kinase (ROCK) plays crucial roles in development across bilaterian animals. The fact that the Rho/Rock pathway is required to initiate epithelial morphogenesis and thus to establish body plans in bilaterians makes this conserved signaling pathway key for studying the molecular mechanisms that may control early development of basally branching metazoans. The purpose of this study was to evaluate whether or not the main components of this signaling pathway exist in sponges, and if present, to investigate the possible role of the regulatory network in an early branching non-bilaterian species by evaluating ROCK function during Ephydatia muelleri development.

The systematics of carnivorous sponges.

Carnivorous sponges are characterized by their unique method of capturing mesoplanktonic prey coupled with the complete or partial reduction of the aquiferous system characteristic of the phylum Porifera. Current systematics place the vast majority of carnivorous sponges within Cladorhizidae, with certain species assigned to Guitarridae and Esperiopsidae. Morphological characters have not been able to show whether this classification is evolutionary accurate, and whether carnivory has evolved once or in several lineages.

Oscarella lobularis (Homoscleromorpha, Porifera) Regeneration: Epithelial Morphogenesis and Metaplasia.

Sponges are known to possess remarkable reconstitutive and regenerative abilities ranging from common wounding or body part regeneration to more impressive re-building of a functional body from dissociated cells. Among the four sponge classes, Homoscleromorpha is notably the only sponge group to possess morphologically distinct basement membrane and specialized cell-junctions, and is therefore considered to possess true epithelia. The consequence of this peculiar organization is the predominance of epithelial morphogenesis during ontogenesis of these sponges.

Insights into Frizzled evolution and new perspectives.

The Frizzled proteins (FZDs) are a family of trans-membrane receptors that play pivotal roles in Wnt pathways and thus in animal development. Based on evaluation of the Amphimedon queenslandica genome, it has been proposed that two Fzd genes may have been present before the split between demosponges and other animals. The major purpose of this study is to go deeper into the evolution of this family of proteins by evaluating an extended set of available data from bilaterians, cnidarians, and different basally branching animal lineages (Ctenophora, Placozoa, Porifera).

Systematics and molecular phylogeny of the family oscarellidae (homoscleromorpha) with description of two new oscarella species.

The family Oscarellidae is one of the two families in the class Homoscleromorpha (phylum Porifera) and is characterized by the absence of a skeleton and the presence of a specific mitochondrial gene, tatC. This family currently encompasses sponges in two genera: Oscarella with 17 described species and Pseudocorticium with one described species. Although sponges in this group are relatively well-studied, phylogenetic relationships among members of Oscarellidae and the validity of genus Pseudocorticium remain open questions.

Cellular and molecular processes leading to embryo formation in sponges: evidences for high conservation of processes throughout animal evolution.

The emergence of multicellularity is regarded as one of the major evolutionary events of life. This transition unicellularity/pluricellularity was acquired independently several times (King 2004). The acquisition of multicellularity implies the emergence of cellular cohesion and means of communication, as well as molecular mechanisms enabling the control of morphogenesis and body plan patterning.

Dissecting the PCP pathway: one or more pathways?: Does a separate Wnt-Fz-Rho pathway drive morphogenesis?

Planar cell polarity (PCP), the alignment of cells within 2D tissue planes, involves a set of core molecular regulators highly conserved between animals and cell types. These include the transmembrane proteins Frizzled (Fz) and VanGogh and the cytoplasmic regulators Dishevelled (Dsh) and Prickle. It is widely accepted that this core forms part of a 'PCP pathway' for signal transduction, which can affect cell morphology through activation of an evolutionary ancient regulatory module involving Rho family GTPases and Myosin II, and/or the JNK kinase cascade.

Molecular phylogeny restores the supra-generic subdivision of homoscleromorph sponges (Porifera, Homoscleromorpha).

Background: Homoscleromorpha is the fourth major sponge lineage, recently recognized to be distinct from the Demospongiae. It contains <100 described species of exclusively marine sponges that have been traditionally subdivided into 7 genera based on morphological characters. Because some of the morphological features of the homoscleromorphs are shared with eumetazoans and are absent in other sponges, the phylogenetic position of the group has been investigated in several recent studies.

Polyphyly of the genus Axinella and of the family Axinellidae (Porifera: Demospongiaep).

The genus Axinella is difficult to define on the basis of morphological characters and includes a heterogeneous assemblage of species. Several previous authors have suspected the polyphyly of both this genus and the family Axinellidae. To clarify the phylogeny of Axinellidae and Axinella, we propose a new hypothesis based on two molecular markers.

Origin and evolution of the Notch signalling pathway: an overview from eukaryotic genomes.

Background: Of the 20 or so signal transduction pathways that orchestrate cell-cell interactions in metazoans, seven are involved during development. One of these is the Notch signalling pathway which regulates cellular identity, proliferation, differentiation and apoptosis via the developmental processes of lateral inhibition and boundary induction. In light of this essential role played in metazoan development, we surveyed a wide range of eukaryotic genomes to determine the origin and evolution of the components and auxiliary factors that compose and modulate this pathway.

Origin of the neuro-sensory system: new and expected insights from sponges.

The capacity of all cells to respond to stimuli implies the conduction of information at least over short distances. In multicellular organisms, more complex systems of integration and coordination of activities are necessary. In most animals, the processing of information is performed by a nervous system.

WNT/beta-catenin signalling and epithelial patterning in the homoscleromorph sponge Oscarella.

Sponges branch basally in the metazoan phylogenetic tree and are thus well positioned to provide insights into the evolution of mechanisms controlling animal development, likely to remain active in adult sponges. Of the four sponge clades, the Homoscleromorpha are of particular interest as they alone show the "true" epithelial organization seen in other metazoan phyla (the Eumetazoa). We have examined the deployment in sponges of Wnt signalling pathway components, since this pathway is an important regulator of many developmental patterning processes.