Cytological and cytochemical investigations of development from dormant gemmules of the marine sponge,Haliclona loosanoffi

Vernalized gemmules of the marine sponge Haliclona loosanoffi were cultured at 20°C, fixed at 24-hour intervals (0–11 days), and processed for light microscopy by using a variety of absorption and fluorescent staining methods. The cytochemistry and morphology of development were compared to the well-studied developmental patterns of freshwater sponges and to the patterns described in the marine sponge Suberites domuncula. The precocious development of H. loosanoffi gemmules involves early morphogenesis occurring within the unhatched gemmule, as opposed to the patterns in freshwater sponges, where most development occurs after the gemmule hatches. Definitive sponge tissue surrounding a single osculum is present 9 days after release from dormancy.     

Ribosomal ITS Sequences Allow Resolution of Freshwater Sponge Phylogeny with Alignments Guided by Secondary Structure Prediction

Freshwater sponges include six extant families which belong to the suborder Spongillina (Porifera). The taxonomy of freshwater sponges is problematic and their phylogeny and evolution are not well understood. Sequences of the ribosomal internal transcribed spacers (ITS1 and ITS2) of 11 species from the family Lubomirskiidae, 13 species from the family Spongillidae, and 1 species from the family Potamolepidae were obtained to study the phylogenetic relationships between endemic and cosmopolitan freshwater sponges and the evolution of sponges in Lake Baikal. The present study is the first one where ITS1 sequences were successfully aligned using verified secondary structure models and, in combination with ITS2, used to infer relationships between the freshwater sponges. Phylogenetic trees inferred using maximum likelihood, neighbor-joining, and parsimony methods and Bayesian inference revealed that the endemic family Lubomirskiidae was monophyletic. Our results do not support the monophyly of Spongillidae because Lubomirskiidae formed a robust clade with E. muelleri, and Trochospongilla latouchiana formed a robust clade with the outgroup Echinospongilla brichardi (Potamolepidae). Within the cosmopolitan family Spongillidae the genera Radiospongilla and Eunapius were found to be monophyletic, while Ephydatia muelleri was basal to the family Lubomirskiidae. The genetic distances between Lubomirskiidae species being much lower than those between Spongillidae species are indicative of their relatively recent radiation from a common ancestor. These results indicated that rDNA spacers sequences can be useful in the study of phylogenetic relationships of and the identification of species of freshwater sponges.     

Sponge cell aggregation: checkpoints in development indicate a high level of organismal complexity

Studies of regeneration provide insight across many scales of animal biology from the processes of cellular communication to the ecology of whole populations. Sponges are highly regenerative animals, with studies showing adults can both recover large portions of their body after predation or damage due to storms, and even reform whole individuals, via an aggregation stage, from dissociated tissues. While sponges are clearly highly regenerative, few studies actually show dissociated cells forming functional individuals. As sponges often serve as model organisms for studying the development and function of traits in metazoans, determining the universality and mechanics of their regeneration potential is important. We tested the capacity of members of seven sponge species from temperate freshwater and marine environments, from a range of taxonomic positions, and with different habits, to form functional sponges after dissociation. Development to a functional sponge progressed through a series of checkpoints: the sorting of cells and removal of debris; adhesion to a substrate and differentiation of cells; organization of cells into tissues; and regionalization of tissues. Two of the seven species tested, Spongilla lacustris and Haliclona cf. permollis, progressed through all four checkpoints, while the remaining five species progressed to various levels of development before aggregates disintegrated. Our findings highlight three important conclusions: (1) The ability of aggregates to differentiate into functional sponges is not as widespread as previously thought; (2) The species‐specific ability of aggregates to develop to functional sponges appears to be an adaptive trait; and (3) The progression of development in aggregates through checkpoints, which in later development involves formation of tissues and regionalization of tissues, highlights the complexity of the sponge body plan and suggests fundamental rules in development shared across metazoans.     

Histology and histochemistry of developing outgrowths of Corvomeyenia carolinensis harrison (Porifera: Spongillidae)

Laboratory-reared outgrowths of the freshwater sponge Corvomeyenia carolinensis Harrison were examined using histological and histochemical techniques, supplemented by phase contrast observations of cellular behavior. The tissue and cellular components of the spongillid outgrowth region were defined in terms of function and morphogenic state. Archeocytes differ considderably, in both histochemical and morphological characteristics, from other cell types of the adult sponge, being histochemically similar to stem cells reported from a variety of developmental series. Archeocytes exhibit cytological characteristics of unspecialized cells capable of high levels of synthetic activity while other cell types of C. carolinensis, for the most part, can be characterized as fully differentiated cells displaying more restricted synthetic capabilities but often accumulating neutral mucoproteins. The presence of aggregates of amebocytes, not identifiable as archeocytes and possibly engaged in gemmule formation, is discussed in terms of current concepts of gemmulation and cellular developmental capabilities in sponges.     

Scanning electron microscopy of taxonomic diagnostic criteria of the freshwater sponge,Heteromeyenia tubisperma (Potts, 1881) (Porifera : Spongillidae)

Taxonomic diagnostic criteria of the spongillid freshwater sponge, Heteromeyenia tubisperma (Potts, 1881) were examined using scanning electron microscopy. The species is characterized by a gemmule which bears an unusually long, prominent porous tube. The application of SEM to the systematic studies of the freshwater sponges provides diagnostic capabilities not available with the light microscope. It is desirable that a key, coupled with a reference atlas of scanning electron micrographs illustrating taxonomic diagnostic criteria of freshwater sponge species, particularly utilizing type specimens, be developed.     

The mitochondrial genome of stygobitic sponge Eunapius subterraneus: mtDNA is highly conserved in freshwater sponges

The complete mitochondrial DNA (mtDNA) genome of the Eunapius subterraneus (Porifera, Demospongiae), a unique stygobitic sponge, was analyzed and compared with previously published mitochondrial genomes from this group. The 24,850 bp long mtDNA genome is circular with the same gene composition as found in other metazoans. Intergenic regions (IGRs) comprise 24.7% of mtDNA and are abundant with direct and inverted repeats and palindromic elements as well as with open reading fames (ORFs) whose distribution and homology was compared with other available mt genomes with a special focus on freshwater sponges. Phylogenetic analyses based on concatenated amino acid sequences from 12 mt protein genes placed E. subterraneus in a well-supported monophyletic clade with the freshwater sponges, Ephydatia muelleri and Lubomirskia baicalensis. Our study showed high homology of mtDNA genomes among freshwater sponges, implying their recent split.     

Xenochironomus ceciliae (Diptera: Chironomidae), a new chironomid species inhabiting freshwater sponges in Brazil

Chironomids living inside freshwater sponges are scarcely known, particularly in the Neotropical region where most of them are to be described. Here, male and female adults, pupa and 4th instar larva of Xenochironomus ceciliae sp. n., living in freshwater sponges of the Paraná River (Brazil) are described. The larval labrum with its several densely setose or combed structures somewhat resembling the filtering structures of simuliid larvae and the predominance of fine detritus in the larval gut contents, may indicate that the larvae of Xenochironomus ceciliae sp. n. are collector-filterers and they might be favored by the aquifer systems of the sponges.     

Phylogenetic position of sponges from Chagatai and Tore-Khol lakes

Morphological and molecular genetic data for freshwater sponges from the lakes of Tuva Depression, Baikalospongia dzhegatajensis (Rezvo, 1936), forms Dzh05 and Dzh06, from Chagatai Lake, as well as forms TKh1 and TKh2, from the Lake Tore-Khol, were obtained and examined. In the sponges examined, which on phylogenetic tree clustered together with the Ephydatia fluviatilis (Linneaus, 1758) sponge from the family Spongillidae, the ITS rDNA regions were sequenced. Comparison of highly variable interal spacer regions of the mitochondrial genome was performed using corresponding sequences of three sponges from the family Spongillidae (E. fluviatilis, E. muelleri and Spongilla lacustris), sponges from the Chagatai and Tore-Khol lakes (Dzh06 and TKh2) with an unknown status, and sponges from the Baikalian family Lubomirskiidae. Minimum genetic differences were observed between E. fluviatilis, Dzh06, and TKh2 (from 0.003 to 0.01% of nucleotide substitutions), while maximum differences were found between the species of Lubomirskiidae and Spongillidae (from 0.928 to 2.06%). The data obtained indicated that sponges from Chagatai and Tore-Khol lakes were most close to E. fluviatilis.     

Two new interesting genera of Gastrotricha (Macrodasyida and Chaetonotida) from the Brazilian freshwater psammon

Two new genera and species of Gastrotricha are described from the psammon of a freshwater body in Brazil: Redudasys fornerise and Arenotus strixinoi. The former is the first undoubted member of the order Macrodasyida recorded from a freshwater environment. It is characterized by the reduction in number of adhesive tubes, the absence of male sexual organs and the presence of a well-developed protonephridial system. The latter belongs to the order Chaetonotida (family Chaetonotidae) and is characterized by the uniform body covering with a thick layer of soft homogeneous cuticle. A possible mode of colonization of fresh waters by marine Macrodasyida, involving colonization of freshwater areas underlying marine beaches, is discussed.     

The choanoderm of Sycettusa hastifera (Calcarea,Porifera) is able to generate new individuals

One of the main characteristics of sponges is their capacity for cell dedifferentiation. This capability can allow an impressive amount of asexual reproduction in these animals, because they are able to develop new individuals from just a few somatic cells. Studies of dedifferentiation, however, have focused mainly on sponges of the class Demospongiae. Therefore, we investigated here whether individuals of three different species of Calcarea are able to reconstitute new individuals following artificial fragmentation. We observed that fragmentation releases clumps of choanoderm able to initiate somatic embryogenesis. In Borojevia brasiliensis (asconoid aquiferous system, subclass Calcinea) and Paraleucilla magna (leuconoid aquiferous system, subclass Calcaronea), these clumps started to develop, but they did not pass through the first developmental phases. In Sycettusa hastifera (syconoid aquiferous system, subclass Calcaronea), the choanoderm was reorganized into primmorphs that fused to each other and formed an exopinacoderm. The first primmorphs’ spicules were triactines. Despite a large mortality rate, the primmorphs developed into olynthus stages. The somatic embryogenesis and the metamorphosis of the olynthus were similar to those observed during the sexual development of this and other calcareous sponge species. Our results show that in S. hastifera, and perhaps in other syconoid calcareous sponges, somatic embryogenesis occurs mainly from choanocytes, at least in vitro. However, primmorph development does not follow the same pattern observed in post‐metamorphic sexual development, as in that case diactines are always the first spicules to be synthesized in calcaronean species.     

Trophic ecology of a freshwater sponge (Spongilla lacustris) revealed by stable isotope analysis

The vital roles that sponges play in marine habitats are well-known. However, sponges inhabiting freshwaters have been largely ignored despite having widespread distributions and often high local abundances. We used natural abundance stable isotope signatures of carbon and nitrogen (δ ¹³C and δ ¹⁵N) to infer the primary food source of the cosmopolitan freshwater sponge Spongilla lacustris. Our results suggest that S. lacustris feed largely on pelagic resources and may therefore link pelagic and benthic food webs. A facultative association between S. lacustris and endosymbiotic green algae caused S. lacustris to have significantly depleted carbon and nitrogen signatures that may reflect carbon and nitrogen exchange between sponges and their symbiotic algae. Isotopic data from specialist sponge consumers demonstrated that sponges hosting zoochlorellae were the major component of the diet of the spongillafly Climacia areolaris and the sponge-eating caddisfly Ceraclea resurgens suggesting that the symbiosis between freshwater sponges and algae is important to sponge predator trophic ecology. Our results help define the role of sponges in freshwater ecosystems and shed new light on the evolution and ecological consequences of a complex tri-trophic symbiosis involving freshwater sponges, zoochlorellae, and spongivorous insects.     

Phylogenetic diversity of bacteria associated with the endemic freshwater sponge Lubomirskia baicalensis

In this study, for the first time the diversity of bacteria associated with the endemic freshwater sponge Lubomirskia baicalensis collected from the Sousern Basin of Lake Baikal was investigated employing cultivation-independent approaches. In total, 102 bacterial 16S rRNA clones were screened using restriction fragment length polymorphism (RFLP) and 30 were selected for sequencing. BLASTN and phylogenetic analysis based on near full length 16S rDNA sequences showed that 22 operational taxonomic units (OTUs) were clustered in six known phyla: Actinobacteria (8 OTUs), alpha-Proteobacteria (4 OTUs), beta-Proteobacteria (4 OTUs), Verrucomicrobia (4 OTUs), Nitrospiracea (1 OTU) and Bacteroidetes (1 OTU). Remarkably all phylotypes were affiliated to uncultured microorganisms, however, all alpha-Proteobacteria sequences were closely related to bacteria derived from the freshwater sponge Spongilla lacustris. Our results reveal a high diversity in the L. baicalensis bacterial community and provide an insight into microbial ecology and diversity within freshwater sponges inhabiting the ancient Lake Baikal ecosystem.     

Life habits and functional morphology of the sediment infaunal spongesOceanapia oleracea andOceanapia peltata (Porifera,Haplosclerida)

Summary In the Santa Marta area of the northern coast of Colombia two species of sponges have been found living within the sediment. The only connection these sponges have with the open water consists of a number of protruding, tubule-like siphons. Through field observations and aquarium experiments, the life habits and the function of the water current system ofOceanapia oleracea andO. peltata have been studied. As an adaptation to life embedded in sediment, both species possess inhalant siphons which draw water from above the sediment surface and duct it to the central body. The inhalant system shows a most unusual separation and concentration of inhalant pores at the tips of the inhalant ducts. The exhalant water leaves the sponge through separate ducts at the opposite side of the central body. Based on the observations onOceanapia, the water flow model forDisyringa proposed by Fry and Fry (1979) is reconsidered.     

Body armour and lateral‐plate reduction in freshwater three‐spined stickleback Gasterosteus aculeatus: adaptations to a different buoyancy regime?

Several factors related to buoyancy were compared between one marine and two freshwater populations of three‐spined stickleback Gasterosteus aculeatus. Fish from all three populations had buoyancy near to neutral to the ambient water. This showed that neither marine nor freshwater G. aculeatus used swimming and hydrodynamic lift to prevent sinking. Comparing the swimbladder volumes showed that freshwater completely plated G. aculeatus had a significantly larger swimbladder volume than both completely plated marine and low‐plated freshwater G. aculeatus. Furthermore, body tissue density was lower in low‐plated G. aculeatus than in the completely plated marine and freshwater fish. The results show that G. aculeatus either reduce tissue density or increase swimbladder volume to adapt to lower water density. Mass measurements of lateral plates and pelvis showed that loss of body armour in low‐plated G. aculeatus could explain the tissue density difference between low‐plated and completely plated G. aculeatus. This suggests that the common occurrence of plate and armour reduction in freshwater G. aculeatus populations can be an adaptation to a lower water density.     

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

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.     

Molecular phylogeny of the freshwater sponges in Lake Baikal

The phylogenetic relationship of the freshwater sponges (Porifera) in Lake Baikal is not well understood. A polyphyletic and/or monophyletic origin have been proposed. The (endemic) Baikalian sponges have been subdivided into two families: endemic Lubomirskiidae and cosmopolitan Spongillidae. In the present study, two new approaches have been made to resolve the phylogenetic relationship of Baikalian sponges; analysis of (1) nucleotide sequences from one mitochondrial gene, the cytochrome oxidase subunit I (COI) and of (2) one selected intron from the tubulin gene. Specimens from the following endemic Baikalian sponge species have been studied; Lubomirskia baicalensis , Baikalospongia intermedia, Baikalospongia recta , Baikalospongia bacillifera and Swartschewskia papyracea . They are all grouped to the family of Lubomirskiidae. Sequence comparisons were performed with the ubiquitously distributed freshwater sponge Spongilla lacustris (family Spongillidae) as well as with one marine sponge, Suberites domuncula . A sequence comparison * * The sequences reported here are being deposited in the EMBL data base. of the mitochondrial COI gene revealed a monophyletic grouping of the endemic Baikalian sponges with S. lacustris as the most related species to the common ancestor. The sequences of the COI gene from B. recta , B. intermedia , B. bacillifera and L. baicalensis were found to be identical and separated from those of S. lacustris and S. papyracea . In a second approach, the exon/intron sequences framing the intron‐2 of the sponge tubulin gene were chosen for the phylogenetic analysis. The intron sequences were aligned and used for construction of a phylogenetic tree. This analysis revealed again a monophyletic grouping with S. lacustris as the closest related species to the common ancestor. It is concluded that the Baikalian sponges, which have been studied here, are of monophyletic origin. Furthermore, the data suggest that the endemic species S. papyracea is the phylogenetically oldest, extant, endemic Baikalian sponge species.     

The dorid nudibranchs Peltodoris lentiginosa and Archidoris odhneri as predators of glass sponges

The dorid nudibranchs Peltodoris lentiginosa and Archidoris odhneri were found on glass sponges (Porifera, Hexactinellida) during remotely operated vehicle surveys of three reefs in the Strait of Georgia, British Columbia, Canada. Eight nudibranchs were sampled from 2009 to 2011. Identification of sponge spicules found in their gut and fecal contents confirmed the nudibranchs to be predators of the reef‐forming hexactinellids Aphrocallistes vastus and Heterochone calyx, as well as of the demosponge Desmacella austini, which encrusts skeletons of the glass sponges. Four of five nudibranchs dissected for gut content analysis had stomachs containing sponge spicules. Counts from high‐definition video footage taken during systematic surveys done in 2009 showed that nudibranchs were found in only two of the three glass sponge reefs. These data provide the first quantitative evidence of a molluscan predator on glass sponges found outside of Antarctica, and establish the first trophic link between glass sponges and their associated community of animals in a sponge reef ecosystem on the western Canadian continental shelf.     

Habitat transitions alter the adaptive landscape and shape phenotypic evolution in needlefishes (Belonidae)

Habitat occupancy can have a profound influence on macroevolutionary dynamics, and a switch in major habitat type may alter the evolutionary trajectory of a lineage. In this study, we investigate how evolutionary transitions between marine and freshwater habitats affect macroevolutionary adaptive landscapes, using needlefishes (Belonidae) as a model system. We examined the evolution of body shape and size in marine and freshwater needlefishes and tested for phenotypic change in response to transitions between habitats. Using micro‐computed tomographic (µCT) scanning and geometric morphometrics, we quantified body shape, size, and vertebral counts of 31 belonid species. We then examined the pattern and tempo of body shape and size evolution using phylogenetic comparative methods. Our results show that transitions from marine to freshwater habitats have altered the adaptive landscape for needlefishes and expanded morphospace relative to marine taxa. We provide further evidence that freshwater taxa attain reduced sizes either through dwarfism (as inferred from axial skeletal reduction) or through developmental truncation (as inferred from axial skeletal loss). We propose that transitions to freshwater habitats produce morphological novelty in response to novel prey resources and changes in locomotor demands. We find that repeated invasions of different habitats have prompted predictable changes in morphology.     

Effect of Himatanthus sucuuba in Maternal Reproductive Outcome and Fetal Anomaly Frequency in Rats

The aim of this study was to evaluate the effect of Himatanthus sucuuba on the maternal reproductive outcome and fetal anomaly incidence in rats. Pregnant rats were randomly divided into three experimental groups as follows: Control = treated with water (vehicle), treated 250 = treated with H. sucuuba at dose 250 mg/kg, and treated 500 = treated with H. sucuuba at dose 500 mg/kg. The rats were orally treated, by gavage, with H. sucuuba or vehicle (water) during preimplantation and organogenic period (from gestational day 0–14). At day 21 of pregnancy, all rats were killed to obtain maternal–fetal data. The treatment with H. sucuuba at dose of 250 mg/kg caused reduction in placental efficiency and an increase preimplantation loss rate and placenta weight compared with the control. The treated 500 group presented a significant decrease in maternal weight gain, maternal weight gain minus gravid uterus weight, fetal weight, and placental efficiency compared with the control. In this group, there was a decrease in body weight at day 20 of pregnancy and metacarpus ossification and an increase in the preimplantation loss rate and skeletal anomalies compared with other groups. Himatanthus sucuuba extract caused intrauterine growth restriction, preimplantation loss, and developmental delay in the high doses tested     

Space as a limiting resource in freshwater systems: competition between zebra mussels (Dreissena polymorpha) and freshwater sponges (Porifera)

Species interactions between two types of sessile benthic invertebrates, the zebra mussel (Dreissena polymorpha) and freshwater sponges (Porifera), were evaluated in Michigan City IN Harbor in southern Lake Michigan during 1996. The study objective was to define whether competition plays a role in structuring benthic communities using experimental techniques commonly employed in marine systems. Sponges were uninhibited by zebra mussel presence and overgrew zebra mussel shells on hard vertical substrata. In contrast, zebra mussels did not overgrow sponge colonies, but did show an ability to re-capture hard substrata if relinquished by the sponge. The negative affect of sponges on zebra mussels through overgrowth and recruitment suggests interactions that could eventually displace zebra mussels from these benthic communities. However, seasonal reduction of sponge biomass from autumn through winter appears to allow the zebra mussel a periodic respite from overgrowth, preventing exclusion of zebra mussels from the community and allowing these two taxa to co-exist.