New lithistid sponge of the genus Sollasipelta (Porifera, Demospongiae,Tetractinellida, Neopeltidae) from submarine caves of the Ryukyu Islands,southwestern Japan, with redescription of S. sollasi

A new species of 'lithistid' (rock sponge) Sollasipelta subterranea sp. nov. is described from near-shore submarine caves of Okinawa and Shimoji Islands, the Ryukyu Islands, southwestern Japan. This new species is characterized by the smooth dentate ectosomal pseudophyllotriaenes, slender choanosomal oxea/style/subtylostyles and two types of amphiasters, one of which is in two size classes. Sollasipelta subterranea sp. nov. is morphologically closest to Sollasipelta sollasi (Lévi & Lévi, 1989), known from the Philippines deep sea, and our examination of the type specimen of S. sollasi revealed that the pseudophyllotriaenes and desmas are substantially different between the two species, and both species possess two types of amphiasters, one of which has two size classes. Sollasipelta cavernicola (Vacelet & Vasseur, 1965) and S. punctata (Lévi & Lévi, 1983) are transferred to the genus Daedalopelta Sollas, 1888, based on possession of one type of amphiastes as microscleres. Sollasipelta mixta (Vacelet, Vasseur and Lévi, 1976) is formally transferred to the genus Neopelta Schmidt, 1880, based on the morphological characters. A key to species of the genus Sollasipelta Van Soest & Hooper, 2020 is also provided. Sollasipelta subterranea sp. nov. represents the first 'lithistid' sponge from submarine caves of the Western Pacific and the first species of sponge inhabiting anchialine cave environments in the Indo-West Pacific. This is also a new record of the family Neopeltidae from Japanese waters.

New species of Abyssocladia and two new cladorhizid genera (Porifera, Cladorhizidae) from New Zealand and Australia

Seamounts on subantarctic New Zealand's Macquarie Ridge, including parts of Australia's Exclusive Economic Zone surrounding Macquarie Island, have been demonstrated to be a rich source of new species of carnivorous sponges (Demospongiae Sollas, Poecilosclerida Topsent, Cladorhizidae Dendy). Four new species of Abyssocladia Lévi, 1964, are described from Macquarie Ridge seamounts and at other disparate locations: Abyssocladia lanceola sp. nov. from Seamounts 7, 8, and 9 (Australia EEZ), Seamount 10 (International Waters), and the South Tasman Rise; Abyssocladia rowdeni sp. nov., first collected from diffuse hydrothermal vent sites at Brothers Seamount on the Southern Kermadec Ridge and recorded here from the non-venting seamounts on Chatham Rise to the east of the South Island of New Zealand; Abyssocladia tumulorum sp. nov., found exclusively on the Chatham Rise; and Abyssocladia sonnae sp. nov. from Monowai Seamount on the Tonga-Kermadec Ridge in International Waters, also found, surprisingly, on Macquarie Ridge's Seamount 8 (Australia EEZ). Patriciacladia gen. nov. has been established for a new species of Cladorhizidae discovered on Macquarie Ridge and Chatham Rise. Patriciacladia enigmatica gen. et sp. nov. is highly unusual in that it possesses palmate isochelae not typically found in Cladorhizidae and has a long branch in phylogenetic analysis of the family, supporting the establishment of a new genus and species for Abyssocladia n. sp. B (QM G339872, was NIWA 41033): 28S rDNA: LN870583, COI: LN870445, Macquarie Ridge) in Hestetun et al. (2016a: table 1; 2017: fig. 15). The discovery of two new species, again from the Macquarie Ridge and other New Zealand locations, expands support for the establishment of a new genus, Australocladia gen. nov., which contains several additional species nested as a monophyletic clade within the large, heterogenous, and paraphyletic Abyssocladia clade in molecular phylogenetic analyses. Australocladia sphaerichela gen. et sp. nov. and Au. alopecura gen. et sp. nov. both possess spherical abyssochelae, funnel-shaped expansions which may contain spermatophores on the body, substrongyles in the attachment base, and a generally southern hemisphere distribution.

Molecular complexity and gene expression controlling cell turnover during a digestive cycle of carnivorous sponge Lycopodina hypogea

Lycopodina hypogea is a carnivorous sponge that tolerates laboratory husbandry very well. During a digestion cycle, performed without any digestive cavity, this species undergoes spectacular morphological changes leading to a total regression of long filaments that ensure the capture of prey and their reformation at the end of the cycle. This phenomenon is a unique opportunity to analyze the molecular and cellular determinants that ensure digestion in the sister group of all other metazoans. Using differential transcriptomic analysis coupled with cell biology studies of proliferation, differentiation, and programmed cell deaths (i.e., autophagy and the destructive/constructive function of apoptosis), we demonstrate that the molecular and cellular actors that ensure digestive homeostasis in a sister group of all remaining animals are similar in variety and complexity to those controlling tissue homeostasis in higher vertebrates. During a digestion cycle, most of these actors are finely tuned in a coordinated manner. Our data benefits from complementary approaches coupling in silico and cell biology studies and demonstrate that the nutritive function is provided by the coordination of molecular network that impacts the cells turnover in the entire organism.

First record of the genus Discorhabdella (Porifera, Demospongiae, Poecilosclerida, Crambeidae) from Sagami Bay, Japan with description of two new species

Two new species of Discorhabdella are described from Sagami Bay, Japan. Discorhabdella has been suggested to have an ancient Tethyan origin according to discovery of their unique pseudoastrose acanthostyles from late Eocene to Oligocene deposits. This is the first record of the genus from the northwest Pacific and first record of the family Crambeidae from Japan. Discorhabdellahispida sp. nov. is distinctive within the genus by possession of special sigmoid microscleres and C-shaped isochelae with short alae. Discorhabdellamisakiensis sp. nov. is characterized by short choanosomal subtylostyles, and their length overlapped with that of the ectosomal subtylostyles. Only one other species, Discorhabdellatuberosocapitata (Topsent, 1890), has the same spicule composition. However, all spicule types are larger in D.tuberosocapitata than those of D.misakiensis sp. nov., and the shape of the isochelae is different: the alae are more widely opened in D.tuberosocapitata. An identification key to species of the genus Discorhabdella is also provided. The discovery of two new species from warm temperate northwest Pacific extends the geographical distribution of the genus Discorhabdella.

Carnivorous sponges (Porifera, Cladorhizidae) from the deep South Pacific (New Caledonia) with the description of three new species of the genus Abyssocladia and remarks on genus Cercicladia

Three new species of carnivorous sponges of the genus Abyssocladia (Demospongiae, Cladorhizidae), A. kanaconi, A. microstrongylata and A. mucronata, are described from the bathyal zone of the Tropical Southwestern Pacific, south of New Caledonia. They were collected in 2016 and 2019 during the KANACONO and KANADEEP 2 expeditions of the Tropical Deep-Sea Benthos program of the French Museum National d'Histoire Naturelle. A new record is reported for the cladorhizid Cercicladia australis Rios, Kelly Vacelet, 2011, and the spicules of the holotype of the type species of Abyssocladia, A. bruuni Lévi, 1964 are illustrated.

Sponge digestive system diversity and evolution: filter feeding to carnivory

Sponges are an ancient basal life form, so understanding their evolution is key to understanding all metazoan evolution. Sponges have very unusual feeding mechanisms, with an intricate network of progressively optimized filtration units: from the simple choanocyte lining of a central cavity, or spongocoel, to more complex chambers and canals. Furthermore, in a single evolutionary event, a group of sponges transitioned to carnivory. This major evolutionary transition involved replacing the filter-feeding apparatus with mobile phagocytic cells that migrate collectively towards the trapped prey. Here, we focus on the diversity and evolution of sponge nutrition systems and the amazing adaptation to carnivory.

Sponge inventory of the French Mediterranean waters, with an emphasis on cave-dwelling species

Mediterranean sponges represent about 10 % of the world sponge biodiversity, with these sessile organisms dominating in terms of diversity and biomass in most of the rocky bottoms shaded from light. After 60 years of intensive study of the sponge diversity along the French coast, we present the first comprehensive reference-list for this biogeographic area. A total of 389 sponge species was recorded, of which 222 known in the Marseille region. In this area, special attention was paid to species from underwater caves. Although this particular habitat appeared as one of the richest, a wealth of hidden diversity still requires description. About 37 % of the sponge diversity can be found in underwater caves, most of these species being also distributed in other habitats. However, 23 % of this sponge diversity is cave-exclusive. An easy and rapid assessment method was developed with a selection of 65 representative sponge species, for the monitoring of semi-dark cave communities. This method, based on data acquisition with photoquadrats and their processing using a DataBase built with ACCESS, was deployed in 13 studied sites. Altogether, this study represents a useful contribution for marine environment managers who might refer to this French reference list and apply the rapid and easy assessment method in the framework of several European Directives and international Conventions.

From marine caves to the deep sea, a new look at Caminella (Demospongiae, Geodiidae) in the Atlanto-Mediterranean region

Caminella Lendenfeld, 1894 is a poorly known Geodiidae genus with unclear phylogenetic relationships. In order to find new lines of evidence that could shed light on the evolutionary history of Caminella, we decided to revise type material and museum material, as well as examine new material from underwater caves and deep-sea ecosystems. In doing so, we formally show that Isops maculosus Vosmaer, 1894 and Caminella loricata Lendenfeld, 1894 are junior synonyms of Caminella intuta (Topsent, 1892). We discuss different spicule morphological phenotypes in C. intuta, which may be linked to silica availability. We also discovered two new species of deep-sea Caminella: 1) from Cape Verde (Caminella caboverdensis sp. nov.) and 2) from seamounts located south of the Azores archipelago and the North of Spain (Caminella pustula sp. nov.). We reveal that Caminella sterrasters have complex surface microstructures, unique amongst the Geodiidae, where actin tips are linked to each other. Molecular markers (COI, 28S (C1-D2) and 18S) sequenced for some specimens led to new phylogenetic analyses, which continue to suggest a close relationship of Caminella with the Erylinae and Calthropella; these affinities are discussed in light of morphological characters.

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.e. Wntless, Wnt ligands and Disheveled), whereas core components of the TGF-β and Notch modules appear unaffected. This suggests that Wnt signaling is not essential for cell differentiation, polarity and morphogenesis in glass sponges. Beyond providing a comparative study of key developmental toolkits, we define here the first case of a metazoan phylum that maintained a level of complexity similar to its relatives despite molecular degeneration of Wnt pathways.

Shaping highly regular glass architectures: A lesson from nature

Demospongiae is a class of marine sponges that mineralize skeletal elements, the glass spicules, made of amorphous silica. The spicules exhibit a diversity of highly regular three-dimensional branched morphologies that are a paradigm example of symmetry in biological systems. Current glass shaping technology requires treatment at high temperatures. In this context, the mechanism by which glass architectures are formed by living organisms remains a mystery. We uncover the principles of spicule morphogenesis. During spicule formation, the process of silica deposition is templated by an organic filament. It is composed of enzymatically active proteins arranged in a mesoscopic hexagonal crystal-like structure. In analogy to synthetic inorganic nanocrystals that show high spatial regularity, we demonstrate that the branching of the filament follows specific crystallographic directions of the protein lattice. In correlation with the symmetry of the lattice, filament branching determines the highly regular morphology of the spicules on the macroscale.

How a collaborative integrated taxonomic effort has trained new spongiologists and improved knowledge of Martinique Island (French Antilles, eastern Caribbean Sea) marine biodiversity

Although sponges are important components of benthic ecosystems of the Caribbean Sea, their diversity remained poorly investigated in the Lesser Antilles. By organizing a training course in Martinique, we wanted both to promote taxonomy and to provide a first inventory of the sponge diversity on this island. The course was like a naturalist expedition, with a field laboratory and a classroom nearby. Early-career scientists and environmental managers were trained in sponge taxonomy. We gathered unpublished data and conducted an inventory at 13 coastal sites. We explored only shallow water habitats (0–30 m), such as mangroves, reefs or rocky bottoms and underwater caves. According to this study, the sponge fauna of Martinique is currently represented by a minimum of 191 species, 134 of which we could assign species names. One third of the remaining non-identified sponge species we consider to be new to science. Martinique appears very remarkable because of its littoral marine fauna harboring sponge aggregations with high biomass and species diversity dominating over coral species. In mangroves, sponges cover about 10% of the surface of subtidal roots. Several submarine caves are true reservoirs of hidden and insufficiently described sponge diversity. Thanks to this new collaborative effort, the Eastern Caribbean has gained a significant increase of knowledge, with sponge diversity of this area potentially representing 40% of the total in the Caribbean Sea. We thus demonstrated the importance of developing exploratory and educational research in areas historically devoid of biodiversity inventories and systematics studies. Finally, we believe in the necessity to consider not only the number of species but their distribution in space to evaluate their putative contribution to ecosystem services and our willingness to preserve them.

Netamines O-S, Five New Tricyclic Guanidine Alkaloids from the Madagascar Sponge Biemna laboutei, and Their Antimalarial Activities

In our continuing program to isolate new compounds from the Madagascar sponge Biemna laboutei, five new tricyclic guanidine alkaloids, netamines O - S (1-5, resp.), have been identified together with the known compounds netamine E (6) and mirabilin J (7). The structures of all new netamines were assigned on the basis of spectroscopic analyses. Their relative configurations were established by analysis of ROESY data and comparison with literature data. Netamines O, P, and Q, which were isolated in sufficient quantities, were tested for their cytotoxic activities against KB cells and their activities against the malaria parasite Plasmodium falciparum. Netamines O and Q were found to be moderately cytotoxic. Netamines O, P, and Q exhibited antiplasmodial activities with IC₅₀ values of 16.99 ± 4.12, 32.62 ± 3.44, and 8.37 ± 1.35 μM, respectively.

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. In the present paper we present the first comprehensive molecular phylogeny of the carnivorous sponges, interpret these results in conjunction with morphological characters, and propose a revised classification of the group. Molecular phylogenies were inferred using 18S rDNA and a combined dataset of partial 28S rDNA, COI and ALG11 sequences. The results recovered carnivorous sponges as a clade closely related to the families Mycalidae and Guitarridae, showing family Cladorhizidae to be monophyletic and also including carnivorous species currently placed in other families. The genus Lycopodina is resurrected for species currently placed in the paraphyletic subgenus Asbestopluma (Asbestopluma) featuring forceps spicules and lacking sigmas or sigmancistras. The genera Chondrocladia and Cladorhiza are found to be monophyletic. However, results indicate that the subgenus Chondrocladia is polyphyletic with respect to the subgenera Meliiderma and Symmetrocladia. Euchelipluma, formerly Guitarridae, is retained, but transferred to Cladorhizidae. The four known carnivorous species currently in Esperiopsis are transferred to Abyssocladia. Neocladia is a junior homonym and is here renamed Koltunicladia. Our results provide strong evidence in support of the hypothesis that carnivory in sponges has evolved only once. While spicule characters mostly reflect monophyletic groups at the generic level, differences between genera represent evolution within family Cladorhizidae rather than evolution of carnivory in separate lineages. Conflicting spicule characters can be reinterpreted to support the inclusion of all carnivorous sponges within Cladorhizidae, and a carnivorous habit should thus be considered the main diagnostic character in systematic classification.

Netamines H-N, tricyclic alkaloids from the marine sponge Biemna laboutei and their antimalarial activity

Chemical examination of the CH2Cl2-MeOH (1:1) extract of the Madagascar sponge Biemna laboutei resulted in the isolation of seven new tricyclic alkaloids, netamines H-N (1-7), along with the known netamine G and mirabilins A, C, and F. Their structures were elucidated by interpretation of 1D and 2D NMR spectra and HRESIMS data. All compounds were evaluated for their cytotoxicity against KB cells and their antiplasmodial activity. Netamine M (6) was found to be cytotoxic, with an IC50 value in the micromolar range, and netamine K (4) exhibited activity against Plasmodium falciparum with an IC50 value of 2.4 μM.

First insights into the microbiome of a carnivorous sponge

Using 454 pyrosequencing, we characterized for the first time the associated microbial community of the deep-sea carnivorous Demosponge Asbestopluma hypogea (Cladorhizidae). Targeting the 16S rRNA gene V3 and V6 hypervariable regions, we compared the diversity and composition of associated microbes of two individual sponges of A. hypogea freshly collected in the cave with surrounding seawater and with one sponge sample maintained 1 year in an aquarium after collection. With more than 22 961 high quality sequences from sponge samples, representing c. 800 operational taxonomic units per sponge sample at 97% sequence similarities, the phylogenetic affiliation of A. hypogea-associated microbes was assigned to 20 bacterial and two archaeal phyla, distributed into 45 classes and 95 orders. Several differences between the sponge and seawater microbes were observed, highlighting a specific and stable A. hypogea microbial community dominated by Proteobacteria and Bacteroidetes and Thaumarchaeota phyla. A high relative abundance of ammonia-oxidizing archaea and a dominance of sulfate oxidizing/reducing bacteria were observed. Our findings shed lights on the potential roles of associated microbial community in the lifestyle of A. hypogea.

Nepheliosyne B, a new polyacetylenic acid from the new caledonian marine sponge Niphates sp

A new C47 polyoxygenated acetylenic acid, nepheliosyne B (2), along with the previously described nepheliosyne A (1), have been isolated from the New Caledonian marine sponge Niphates sp. Their structures have been elucidated on the basis of extensive spectroscopic analyses. These metabolites exhibited a moderate cytotoxicity against K562, U266, SKM1, and Kasumi cancer cell lines.

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. Here we present a phylogenetic analysis of Oscarellidae using four markers (18S rDNA, 28S rDNA, atp6, tatC), and argue that it should become a mono-generic family, with Pseudocorticium being synonymized with Oscarella, and with the transfer of Pseudocorticium jarrei to Oscarella jarrei. We show that the genus Oscarella can be subdivided into four clades, each of which is supported by either a small number of morphological characters or by molecular synapomorphies. In addition, we describe two new species of Oscarella from Norwegian fjords: O. bergenensis sp. nov. and O. nicolae sp. nov., and we compare their morphology, anatomy, and cytology with other species in this genus. Internal anatomical characters are similar in both species, but details of external morphology and particularly of cytological characters provide diagnostic features. Our study also confirms that O. lobularis and O. tuberculata are two distinct polychromic sibling species. This study highlights the difficulties of species identification in skeleton-less sponges and, more generally, in groups where morphological characters are scarce. Adopting a multi-marker approach is thus highly suitable for these groups.

A giant foraminifer that converges to the feeding strategy of carnivorous sponges: Spiculosiphon oceana sp. nov. (Foraminifera, Astrorhizida)

The foraminifer Spiculosiphon oceana sp. nov. is a giant (>4 cm) agglutinated astrorhizid, which makes the second known species of this unusual genus and its first Mediterranean record. It has a peculiar stalked, capitate, monothalamous test. Bleach digestion and X-ray microanalysis indicated the test to be made exclusively of siliceous sponge spicules agglutinated in organic cement. The organism stands on a hollow, 4 cm long, 0.5 cm thick stalk built with highly selected, long and thin spicule fragments, tightly cemented together in parallel to the main axis of the stalk. The proximal end of the stalk is closed and slightly expanded into a bulb-like structure, designed to penetrate between the sand grains and maintaining the test upright while avoiding a permanent attachment to the substratum. The distal stalk end becomes a hollow, globe-like structure that contains the main protoplasm. The globelike region is built with loosely agglutinated and irregularly-shaped spicules, allowing extrusion of the pseudopodia through the cavities between the spicules. The globelike structure also serves as an anchoring basis, from which long and thin, solid tracts protrude radially to make a spherical crown that attains about 4 mm in total diameter. The radiating tracts are built with highly selected aciculate spicule fragments held together with a translucent organic cement. They provide skeletal support for the extension of a crown of pseudopodia into the water column. This arrangement is thought to enhance the chances of the pseudopodia to contact demersal planktonic prey. In summary, Spiculosiphon species collect and arrange sponge spicules with high selectivity to recreate a body morphology that strongly converges to that of some carnivorous sponges, which allows these predatory foraminifera to exploit a prey capturing strategy similar to that of the carnivorous sponges. This idea is also consistent with our report of an additional, yet undetermined, Spiculosiphon species occurring in the same sublittoral Mediterranean cave where carnivorous sponges were first discovered.

Global diversity of sponges (Porifera)

With the completion of a single unified classification, the Systema Porifera (SP) and subsequent development of an online species database, the World Porifera Database (WPD), we are now equipped to provide a first comprehensive picture of the global biodiversity of the Porifera. An introductory overview of the four classes of the Porifera is followed by a description of the structure of our main source of data for this paper, the WPD. From this we extracted numbers of all 'known' sponges to date: the number of valid Recent sponges is established at 8,553, with the vast majority, 83%, belonging to the class Demospongiae. We also mapped for the first time the species richness of a comprehensive set of marine ecoregions of the world, data also extracted from the WPD. Perhaps not surprisingly, these distributions appear to show a strong bias towards collection and taxonomy efforts. Only when species richness is accumulated into large marine realms does a pattern emerge that is also recognized in many other marine animal groups: high numbers in tropical regions, lesser numbers in the colder parts of the world oceans. Preliminary similarity analysis of a matrix of species and marine ecoregions extracted from the WPD failed to yield a consistent hierarchical pattern of ecoregions into marine provinces. Global sponge diversity information is mostly generated in regional projects and resources: results obtained demonstrate that regional approaches to analytical biogeography are at present more likely to achieve insights into the biogeographic history of sponges than a global perspective, which appears currently too ambitious. We also review information on invasive sponges that might well have some influence on distribution patterns of the future.

Relevance of an integrative approach for taxonomic revision in sponge taxa: case study of the shallow-water Atlanto-Mediterranean Hexadella species (Porifera:Ianthellidae:Verongida)

The identification of sponges that lack a mineral skeleton is always highly challenging, especially for Hexadella species, which are also fibreless. Recently, the yellow species Hexadella pruvoti Topsent was identified as a cryptic species complex while the pink coloured Hexadella racovitzai Topsent showed two highly divergent lineages. We performed a COI phylogenetic reconstruction using 27 new Mediterranean Hexadella samples in order to confirm the presence of divergent lineages within both shallow-water species. Specimens were described with an integrative approach combining morphological and cytological investigations, biochemical profiling and assessment of natural toxicity in order to identify diagnostic characters for each taxon. H. topsenti, sp. nov. is distinguished from H. racovitzai by its colour, its surface network shape, divergent secondary metabolite patterns and toxicity values. H. crypta, sp. nov. differs from H. pruvoti by a different encrusting growth form when alive, and by distinctively colouring the ethanol fixative solution. In addition, H. pruvoti and H. crypta show different types of cells with inclusions as well as distinct metabolic fingerprints. Natural toxicity values, however, do not permit the separation of H. pruvoti and H. crypta. Our work shows that only the use of a combination of complementary tools can provide relevant descriptions for some problematic taxa.

Cell death and renewal during prey capture and digestion in the carnivorous sponge Asbestopluma hypogea (Porifera: Poecilosclerida)

The sponge Asbestopluma hypogea is unusual among sponges due to its peculiar carnivorous feeding habit. During various stages of its nutrition cycle, the sponge is subjected to spectacular morphological modifications. Starved animals are characterized by many elongated filaments which are crucial for the sponge to capture prey. After capture, and during the digestion process, these filaments actively regress before being regenerated during a subsequent period of starvation. Here, we demonstrate that these morphological events repose on a highly dynamic cellular turnover implying a coordinated sequence of programmed cell death (apoptosis and autophagy), cell proliferation and cell migration. A candidate niche for cell renewal by stem cell proliferation and differentiation was identified at the base of the sponge peduncle, characterized by surpassing levels of BrdU/EdU incorporation. Therefore, BrdU/EdU positive-cells of the peduncle base are candidate motile cells responsible for the regeneration of the prey-capturing main sponge body, i.e. the dynamic filaments. Altogether, our results demonstrate that dynamic of cell renewal in sponge appears to be regulated by cellular mechanisms as multiple and complex as those already identified in bilaterian metazoans.

Assessing the complex sponge microbiota: core, variable and species-specific bacterial communities in marine sponges

Marine sponges are well known for their associations with highly diverse, yet very specific and often highly similar microbiota. The aim of this study was to identify potential bacterial sub-populations in relation to sponge phylogeny and sampling sites and to define the core bacterial community. 16S ribosomal RNA gene amplicon pyrosequencing was applied to 32 sponge species from eight locations around the world's oceans, thereby generating 2567 operational taxonomic units (OTUs at the 97% sequence similarity level) in total and up to 364 different OTUs per sponge species. The taxonomic richness detected in this study comprised 25 bacterial phyla with Proteobacteria, Chloroflexi and Poribacteria being most diverse in sponges. Among these phyla were nine candidate phyla, six of them found for the first time in sponges. Similarity comparison of bacterial communities revealed no correlation with host phylogeny but a tropical sub-population in that tropical sponges have more similar bacterial communities to each other than to subtropical sponges. A minimal core bacterial community consisting of very few OTUs (97%, 95% and 90%) was found. These microbes have a global distribution and are probably acquired via environmental transmission. In contrast, a large species-specific bacterial community was detected, which is represented by OTUs present in only a single sponge species. The species-specific bacterial community is probably mainly vertically transmitted. It is proposed that different sponges contain different bacterial species, however, these bacteria are still closely related to each other explaining the observed similarity of bacterial communities in sponges in this and previous studies. This global analysis represents the most comprehensive study of bacterial symbionts in sponges to date and provides novel insights into the complex structure of these unique associations.

Structure elucidation of the new citharoxazole from the Mediterranean deep-sea sponge Latrunculia (Biannulata) citharistae

Citharoxazole (1), a new batzelline derivative featuring a benzoxazole moiety, was isolated from the Mediterranean deep-sea sponge Latrunculia (Biannulata) citharistae Vacelet, 1969, together with the known batzelline C (2). This is the first chemical study of a Mediterranean Latrunculia species and the benzoxazole moiety is unprecedented for this family of marine natural products. The structure was mainly elucidated by the interpretation of NMR spectra and especially HMBC correlations.

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. Among the most basal taxa, sponges are nerveless so that it is traditionally assumed that the integrated neuro-sensory system originated only once in Eumetazoa, a hypothesis not in agreement with some recent phylogenomic studies. The aim of this review is to show that recent data on sponges might provide clues for understanding the origin of this complex system. First, sponges are able to react to external stimuli, and some of them display spontaneous movement activities. These coordinated behaviors involve nervous system-like mechanisms, such as action potentials and/or neurotransmitters. Second, genomic analyses show that sponges possess genes orthologous to those involved in the patterning or functioning of the neuro-sensory system in Eumetazoa. Finally, some of these genes are expressed in specific cells (flask cells, choanocytes). Together with ultrastructural data, this gives rise to challenging hypotheses concerning cell types that might play neuro-sensory-like roles in sponges.

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. However, the phylogenetic relationships within the group remain unexplored by modern methods.

Methodology/Principal Findings

Here we describe the first molecular phylogeny of Homoscleromorpha based on nuclear (18S and 28S rDNA) and complete mitochondrial DNA sequence data that focuses on inter-generic relationships. Our results revealed two robust clades within this group, one containing the spiculate species (genera Plakina, Plakortis, Plakinastrella and Corticium) and the other containing aspiculate species (genera Oscarella and Pseudocorticium), thus rejecting a close relationship between Pseudocorticium and Corticium. Among the spiculate species, we found affinities between the Plakortis and Plakinastrella genera, and between the Plakina and Corticium. The validity of these clades is furthermore supported by specific morphological characters, notably the type of spicules. Furthermore, the monophyly of the Corticium genus is supported while the monophyly of Plakina is not.

Conclusions/Significance

As the result of our study we propose to restore the pre-1995 subdivision of Homoscleromorpha into two families: Plakinidae Schulze, 1880 for spiculate species and Oscarellidae Lendenfeld, 1887 for aspiculate species that had been rejected after the description of the genus Pseudocorticium. We also note that the two families of homoscleromorphs exhibit evolutionary stable, but have drastically distinct mitochondrial genome organizations that differ in gene content and gene order.

Cell kinetics of the marine sponge Halisarca caerulea reveal rapid cell turnover and shedding

This study reveals the peculiar in vivo cell kinetics and cell turnover of the marine sponge Halisarca caerulea under steady-state conditions. The tropical coral reef sponge shows an extremely high proliferation activity, a short cell cycle duration and massive cell shedding. Cell turnover is predominantly confined to a single cell population, i.e. the choanocytes, and in this process apoptosis only plays a minor role. To our knowledge, such fast cell kinetics under steady-state conditions, with high turnover by shedding in the absence of apoptosis, has not been observed previously in any other multicellular organism. The duration of the cell cycle in vivo resembles that of unicellular organisms in culture. Morphological and histochemical studies demonstrate compartmentalization of choanocytes in the sponge tissue, which corresponds well with its remarkable cellular kinetics. Coral reef cavity sponges, like H. caerulea, inhabit low nutrient tropical waters, forcing these organisms to filter large volumes of water and to capture the few nutrients efficiently. Under these oligotrophic conditions, a high cell turnover may be considered as a very useful strategy, preventing permanent damage to the sponge by environmental stress. Halisarca caerulea maintains its body mass and keeps its food uptake system up to date by constantly renewing its filter system. We conclude that studies on cell kinetics and functional morphology provide new and essential information on the growth characteristics and the regulation of sponge growth in vivo as well as in vitro and the role of choanocytes in tissue homeostasis.

Salaramides A and B; two alpha-oxoamides isolated from the marine sponge Hippospongia sp. (Porifera, Dictyoceratida)

Two novel alpha-oxoamides, salaramide A (1) and its homologue salaramide B (2), were isolated from the Madagascar marine sponge, Hippospongia sp., collected in Salary Bay, north of Tulear. The structures of 1 and 2 were elucidated by interpretation of mass spectra, 1D and 2D NMR spectra, and confirmed by chemical transformation.

Salaramides A and B; Two α-Oxoamides Isolated from the Marine Sponge Hippospongia sp. (Porifera, Dictyoceratida)

Two novel α-oxoamides, salaramide A (1) and its homologue salaramide B (2), were isolated from the Madagascar marine sponge, Hippospongia sp., collected in Salary Bay, north of Tulear. The structures of 1 and 2 were elucidated by interpretation of mass spectra, 1D and 2D NMR spectra, and confirmed by chemical transformation.

Plakinamine L: a new steroidal alkaloid from the marine sponge Corticium sp

A new steroidal alkaloid, plakinamine L (1) with an unprecedented acyclic side chain, was isolated from the marine sponge Corticium sp. collected near Salary (south-west of Madagascar). The structure was elucidated by combined spectroscopic methods.

Plakinamine L: A New Steroidal Alkaloid from the Marine Sponge Corticium sp

A new steroidal alkaloid, plakinamine L (1) with an unprecedented acyclic side chain, was isolated from the marine sponge Corticium sp. collected near Salary (south-west of Madagascar). The structure was elucidated by combined spectroscopic methods.

Bioactive guanidine alkaloids from two Caribbean marine sponges

Seven new guanidine alkaloids (1-7) together with the known batzelladines A, F, H, and L, ptilomycalin A, and fromiamycalin were isolated from the Caribbean marine sponges Monanchora arbuscula and Clathria calla. Molecular structures were assigned on the basis of detailed analysis of 1D and 2D NMR spectra and mass spectrometry data, and bioactivities of the alkaloids were evaluated against human cancer cell lines and malaria protozoa.

The Homoscleromorph sponge Oscarella lobularis, a promising sponge model in evolutionary and developmental biology: model sponge Oscarella lobularis

Sponges branch basally in the metazoan phylogenetic tree and are believed to be composed of four distinct lineages with still uncertain relationships. Indeed, some molecular studies propose that Homoscleromorpha may be a fourth Sponge lineage, distinct from Demospongiae in which they were traditionally classified. They harbour many features that distinguish them from other sponges and are more evocative of those of the eumetazoans. They are notably the only sponges to possess a basement membrane with collagen IV and specialized cell-junctions, thus possessing true epithelia. Among Homoscleromorphs, we have chosen Oscarella lobularis as a model species. This common and easily accessible sponge is characterized by relatively simple histology and cell composition, absence of skeleton, and strongly pronounced epithelial structure. In this review, we explore the specific features that make O. lobularis a promising homoscleromorph sponge model for evolutionary and developmental researches.

Phylogenomics revives traditional views on deep animal relationships

The origin of many of the defining features of animal body plans, such as symmetry, nervous system, and the mesoderm, remains shrouded in mystery because of major uncertainty regarding the emergence order of the early branching taxa: the sponge groups, ctenophores, placozoans, cnidarians, and bilaterians. The "phylogenomic" approach [1] has recently provided a robust picture for intrabilaterian relationships [2, 3] but not yet for more early branching metazoan clades. We have assembled a comprehensive 128 gene data set including newly generated sequence data from ctenophores, cnidarians, and all four main sponge groups. The resulting phylogeny yields two significant conclusions reviving old views that have been challenged in the molecular era: (1) that the sponges (Porifera) are monophyletic and not paraphyletic as repeatedly proposed [4-9], thus undermining the idea that ancestral metazoans had a sponge-like body plan; (2) that the most likely position for the ctenophores is together with the cnidarians in a "coelenterate" clade. The Porifera and the Placozoa branch basally with respect to a moderately supported "eumetazoan" clade containing the three taxa with nervous system and muscle cells (Cnidaria, Ctenophora, and Bilateria). This new phylogeny provides a stimulating framework for exploring the important changes that shaped the body plans of the early diverging phyla.

Sponge paraphyly and the origin of Metazoa

In order to allow critical evaluation of the interrelationships between the three sponge classes, and to resolve the question of mono- or paraphyly of sponges (Porifera), we used the polymerase chain reaction (PCR) to amplify almost the entire nucleic acid sequence of the 18S rDNA from several hexactinellid, demosponge and calcareous sponge species. The amplification products were cloned, sequenced and then aligned with previously reported sequences from other sponges and nonsponge metazoans and variously distant outgroups, and trees were constructed using both neighbour-joining and maximum parsimony methods. Our results suggest that sponges are paraphyletic, the Calcarea being more related to monophyletic Eumetazoa than to the siliceous sponges (Demospongiae, Hexactinellida). These results have important implications for our understanding of metazoan origins, because they suggest that the common ancestor of Metazoa was a sponge. They also have consequences for basal metazoan classification, implying that the phylum Porifera should be abandoned. Our results support the upgrading of the calcareous sponge class to the phylum level.

NK homeobox genes with choanocyte-specific expression in homoscleromorph sponges

Data on nonbilaterian animals (sponges, cnidarians, and ctenophores) have suggested that Antennapedia (ANTP) class homeobox genes played a crucial role in the early diversification of animal body plans. Estimates of ancestral gene diversity within this important class of developmental regulators have been mostly based on recent analyses of the complete genome of a demosponge species, leading to the proposal that all ANTP families found in nonsponges animals (eumetazoans) derived from an ancestral "proto-NK" six-gene cluster. However, a single sponge species cannot reveal ancestral metazoan traits, in particular because lineage-specific gene duplications or losses are likely to have occurred during the long history of the Porifera. We thus looked for ANTP genes by degenerate polymerase chain reaction search in five species belonging to the Homoscleromorpha, a sponge lineage recently phylogenetically classified outside demosponges and characterized by unique histological features. We identified new genes of the ANTP class called HomoNK. Our phylogenetic analyses placed HomoNK (without significant support) close to the NK6 and NK7 families of cnidarian and bilaterian ANTP genes and did not recover the monophyly of the proposed "proto-NK" cluster. Our expression analyses of the HomoNK gene OlobNK in adult Oscarella lobularis showed that this gene is a strict marker of choanocytes, the most typical sponge cell type characterized by an apical flagellum surrounded by a collar of microvilli. These results are discussed in the light of the predominant neurosensory expression of NK6 and NK7 genes in bilaterians and of the recent proposal that choanocytes could be the sponge homologs of sensory cells.

5α, 8α-Epidioxysterol from the marine sponge Biemna Triraphis Topsent

5α, 8α-Epidioxy-24( S)-ethylcholest-6-en-3β-ol (1) was isolated from the marine sponge Biemna triraphis Topsent collected at Andavadoaka, near Toliary (west coast of Madagascar-Indian Ocean). The structure was elucidated from NMR spectroscopic data. This is the first report of this compound in a marine sponge belonging to the Biemna genus.

Marine bifunctional sphingolipids from the sponge Oceanapia ramsayi

During the course of our continuing studies on marine natural lipid products,two known sphingolipids have been isolated for the first time from a specimen of the marine sponge Oceanapia ramsayi collected at Itampolo on the west coast of Madagascar in the Indian Ocean. The structures were elucidated using NMR data and by comparison with literature data. The occurrence of these sphingolipids within other Oceanapia spp. is discussed.

Ptilomycalin D, a polycyclic guanidine alkaloid from the marine sponge Monanchora dianchora

A new polycyclic guanidine alkaloid, ptilomycalin D, and the known crambescidic acid were isolated from the marine sponge Monanchora dianchora collected in Nosy-Be, northwest of Madagascar, in the Indian Ocean. The structures were elucidated using 1- and 2-D NMR and MS data, and their biogenetic implications are discussed.

Molecular phylogeny of Demospongiae: implications for classification and scenarios of character evolution

An analysis of the phylogenetic relationships of the 13 orders of Demospongiae, based on 18S and C1, D1 and C2 domains of 28S rRNA (for, respectively, 26 and 32 taxa) has been performed. The class Demospongiae as traditionally defined is not found to be monophyletic. Instead, a clade comprising all demosponges except Homoscleromorpha is well-supported, and we define phylogenetically the name Demospongiae in this more restricted sense to preclude the possibility of drastic alterations of the meaning of Demospongiae in the future, depending on the position of Homoscleromorpha. Within this clade Demospongiae s.s., ceractinomorphs and tetractinomorphs are polyphyletic, implying homoplastic evolution of characters such as reproductive strategies (viviparity vs. oviparity) and skeleton architecture (reticulate vs. radiate). The topology derived from our molecular data provides a basis for proposing a new classification of Demospongiae s.s., and suggests a reverse polarity of some characters, with respect to traditional conceptions: viviparity, presence of monaxon spicules and of spongin appear to be ancestral, whereas oviparity, and presence of tetraxon spicules appear as derived characters.

Effects of 12 years' operation of a sewage treatment plant on trace metal occurrence within a Mediterranean commercial sponge (Spongia officinalis, Demospongiae)

The present field study uses Spongia officinalis for assessing trace metals occurrence in time and space within Mediterranean rocky communities. Nine sites were selected in the Marseille area for studying spatial trends in 12 metal concentrations. Long term changes in 8 metal concentrations were assessed at sites that had been sampled before and 12 years after the opening of a treatment plant. Spongia officinalis highly concentrated all the trace metal surveyed excepted Hg and Cd. The overall contamination level registered provided a classification of the study sites which is congruent with that given by other studies on pollutant accumulation in neighbouring sandy-bottoms or benthic assemblages. Among the metals studied, Fe, Pb, Cr are those that best highlighted a pollution gradient. In the present study, only Cd concentration did not vary in space. Except for Ni, all pollutant concentrations clearly decreased between 1984 and 1999. This very impressive decrease in heavy metal concentrations within the Marseille area represents an indisputable evidence of the improvement of the seawater quality resulting from 12 years' operation of the Marseille sewage plant. Moreover, the significant decrease also recorded in the reference population at Port-Cros might reflect an overall improvement in the seawater quality of the NW Mediterranean.