Discovery of the freshwater sponge genus Corvospongilla Annandale (Porifera: Spongillida) in Australia with the description of a new species and phylogeographic implications

A recent discovery of freshwater sponges in an unexplored hydrographic basin in north-western Australia provided the opportunity to investigate the genus Corvospongilla Annandale (Spongillida: Spongillidae) using integrative systematics. Emendation of the genus diagnosis is provided. A comparative analysis of a Corvospongilla global dataset of morphological traits together with biogeographic patterns disclosed a new Australasian Corvospongilla species and along with molecular analyses provided the basis for a phylogenetic and phylogeographic tree for some Asian, Afrotropical and Australasian lineages.

Ambientes de ocorrência do porífero Oncosclera jewelli no Parque Estadual Do Tainhas, Planalto Meridional do RS: uma análise geomorfométrica

Tainhas State Park embraces locations of occurrence of freshwater sponge Oncosclera jewelli. Our objective is to indicate the areas of potential occurrence of the species from factors related to the geomorphometric signature of the occurance points along the Tainhas River in the Park and its buffer zone. Connections and data analysis were performed from the construction and manipulation of a geographic database, in SIGs SPRING-5.4.3 and QGIS-2.18, containing: a) MDEs from Topodata, Embrapa and Alos bases, obtained by remote orbitals sensors for the entire study area, and MDE obtained by drone-generated aerial images of the geomorphometric variables: slope, aspect and topographic position index; b) geological map of Rio Grande do Sul; c) land use and coverage map, based on images from the GeoEye satellite. The results demonstrated that the species occurs exclusively on the lithological unit of Serra Geral Formation. The plain is marked by terrain of low slope and south and east orientation and flattened plains. The Potential Occurrence Map of the species was generated, demonstrating that approximately 4.5% of the total length of watercourse stretches in the study area meet the analyzed geomorphometric conditions.

Freshwater sponge hosts and their green algae symbionts: a tractable model to understand intracellular symbiosis

In many freshwater habitats, green algae form intracellular symbioses with a variety of heterotrophic host taxa including several species of freshwater sponge. These sponges perform important ecological roles in their habitats, and the poriferan:green algae partnerships offers unique opportunities to study the evolutionary origins and ecological persistence of endosymbioses. We examined the association between Ephydatia muelleri and its chlorophyte partner to identify features of host cellular and genetic responses to the presence of intracellular algal partners. Chlorella-like green algal symbionts were isolated from field-collected adult E. muelleri tissue harboring algae. The sponge-derived algae were successfully cultured and subsequently used to reinfect aposymbiotic E. muelleri tissue. We used confocal microscopy to follow the fate of the sponge-derived algae after inoculating algae-free E. muelleri grown from gemmules to show temporal patterns of symbiont location within host tissue. We also infected aposymbiotic E. muelleri with sponge-derived algae, and performed RNASeq to study differential expression patterns in the host relative to symbiotic states. We compare and contrast our findings with work in other systems (e.g., endosymbiotic Hydra) to explore possible conserved evolutionary pathways that may lead to stable mutualistic endosymbioses. Our work demonstrates that freshwater sponges offer many tractable qualities to study features of intracellular occupancy and thus meet criteria desired for a model system.

Genome Analysis of Two Bacterial Strains Isolated from Diseased Freshwater Sponge Reveals the Probable Cause of Its Joint Domination in Microbial Community

Endemic freshwater sponges (Demosponges, Lubomirskiidae) dominate in Lake Baikal and are multicellular filter-feeding animals represent a complex consortium of many species of eukaryotes and prokaryotes. In recent years, mass disease and death of the L. baicalensis have been an urgent problem of Lake Baikal. The etiology and ecology of these events remain unknown. Bacteria in microbiomes of diseased sponges of the families Flavobacteriaceae and Oxalobacteraceae were dominant. Both species are opportunistic pathogens common for freshwater ecosystems. The aim of our study is to analyze the genomes of strains Janthinobacterium sp. SLB01 and Flavobacterium sp. SLB02, isolated from diseased sponges to identify the reasons for their joint dominance. The first one attacks the other cells using type VI secretion system, suppress gram-positive bacteria with violacein pigment and regulate its own activity via quorum sensing. It makes the floc and strong biofilm by exopolysaccharide biosynthesis and PEP‐CTERM proteins expression. The second one utilizes the fragments of cell walls produced of polysaccharides. Named two strains have noticeable difference in carbohydrates acquisition. We described the possible way of joint occupation of ecological niche into freshwater sponge microbial community. This study expands understanding about symbiotic relationship of microorganisms with freshwater Baikal sponges.

Freshwater sponge hosts and their green algae symbionts: a tractable model to understand intracellular symbiosis

In many freshwater habitats, green algae form intracellular symbioses with a variety of heterotrophic host taxa including several species of freshwater sponge. These sponges perform important ecological roles in their habitats, and the poriferan:green algae partnerships offers unique opportunities to study the evolutionary origins and ecological persistence of endosymbioses. We examined the association between Ephydatia muelleri and its chlorophyte partner to identify features of host cellular and genetic responses to the presence of intracellular algal partners. Chlorella-like green algal symbionts were isolated from field-collected adult E. muelleri tissue harboring algae. The sponge-derived algae were successfully cultured and subsequently used to reinfect aposymbiotic E. muelleri tissue. We used confocal microscopy to follow the fate of the sponge-derived algae after inoculating algae-free E. muelleri grown from gemmules to show temporal patterns of symbiont location within host tissue. We also infected aposymbiotic E. muelleri with sponge-derived algae, and performed RNASeq to study differential expression patterns in the host relative to symbiotic states. We compare and contrast our findings with work in other systems (e.g., endosymbiotic Hydra) to explore possible conserved evolutionary pathways that may lead to stable mutualistic endosymbioses. Our work demonstrates that freshwater sponges offer many tractable qualities to study features of intracellular occupancy and thus meet criteria desired for a model system.

Adhesion of freshwater sponge cells mediated by carbohydrate–carbohydrate interactions requires low environmental calcium

Marine ancestors of freshwater sponges had to undergo a series of physiological adaptations to colonize harsh and heterogeneous limnic environments. Besides reduced salinity, river-lake systems also have calcium concentrations far lower than seawater. Cell adhesion in sponges is mediated by calcium-dependent multivalent self-interactions of sulfated polysaccharide components of membrane-bound proteoglycans named aggregation factors. Cells of marine sponges require seawater average calcium concentration (10 mM) to sustain adhesion promoted by aggregation factors. We demonstrate here that the freshwater sponge Spongilla alba can thrive in a calcium-poor aquatic environment and that their cells are able to aggregate and form primmorphs with calcium concentrations 40-fold lower than that required by marine sponges cells. We also find that their gemmules need calcium and other micronutrients to hatch and generate new sponges. The sulfated polysaccharide purified from S. alba has sulfate content and molecular size notably lower than those from marine sponges. Nuclear magnetic resonance analyses indicated that it is composed of a central backbone of non- and 2-sulfated α- and β-glucose units decorated with branches of α-glucose. Assessments with atomic force microscopy/single-molecule force spectroscopy show that S. alba glucan requires 10-fold less calcium than sulfated polysaccharides from marine sponges to self-interact efficiently. Such an ability to retain multicellular morphology with low environmental calcium must have been a crucial evolutionary step for freshwater sponges to successfully colonize inland waters.