Systematic revision of the genus Petromica Topsent (Demospongiae: Halichondrida), with a new species from the southwestern Atlantic

The status, scope and classification of the sublithistid demosponge genus Petromica Topsent are revised through morphological analysis of museum specimens of all seven species (including proposed synonyms and varieties), two of which were collected and observed in situ along the Brazilian coast (P. ciocalyptoides (Van Soest & Zea) and P. citrina sp. n.). The synonymy of Petromica and Monanthus Kirkpatrick with priority to the former is justified due to the consistent presence of monocrepid rhizoclone desmas and oxeas in an halichondroid arrangement, and to the lack of co-variance in other morphological characters among the species studied (presence and shape of papillae, surface texture, ectosomal skeleton and desma shape). The proposed synonymy of P. grimaldii Topsent and P. massalis Dendy is refuted due to differences in habit and spicule shape between the two species. Three forms described as varieties of Monanthus plumosus Kirkpatrick are raised to species level: P. plumosa (Kirkpatrick), P. tubulata (Kirkpatrick) and P. digitata (Burton). Phylogenetic analysis indicates that two possibly monophyletic clades may be recognized within Petromica, although with low bootstrap support (35–59%): (P. ciocalyptoides, P. citrina) and (P. grimaldii, P. massalis) (P. plumosa) (P. tubulata) (P. digitata). The classification of Petromica within the Halichondriidae (order Halichondrida) is supported by the confused reticulation of long oxeote spicules with ascending spicule tracts, present in all species of the genus.     

Environmental shaping of sponge associated archaeal communities

Background

Archaea are ubiquitous symbionts of marine sponges but their ecological roles and the influence of environmental factors on these associations are still poorly understood.

Methodology/Principal Findings

We compared the diversity and composition of archaea associated with seawater and with the sponges Hymeniacidon heliophila, Paraleucilla magna and Petromica citrina in two distinct environments: Guanabara Bay, a highly impacted estuary in Rio de Janeiro, Brazil, and the nearby Cagarras Archipelago. For this we used metagenomic analyses of 16S rRNA and ammonia monooxygenase (amoA) gene libraries. Hymeniacidon heliophila was more abundant inside the bay, while P. magna was more abundant outside and P. citrina was only recorded at the Cagarras Archipelago. Principal Component Analysis plots (PCA) generated using pairwise unweighted UniFrac distances showed that the archaeal community structure of inner bay seawater and sponges was different from that of coastal Cagarras Archipelago. Rarefaction analyses showed that inner bay archaeaoplankton were more diverse than those from the Cagarras Archipelago. Only members of Crenarchaeota were found in sponge libraries, while in seawater both Crenarchaeota and Euryarchaeota were observed. Although most amoA archaeal genes detected in this study seem to be novel, some clones were affiliated to known ammonia oxidizers such as Nitrosopumilus maritimus and Cenarchaeum symbiosum.

Conclusion/Significance

The composition and diversity of archaeal communities associated with pollution-tolerant sponge species can change in a range of few kilometers, probably influenced by eutrophication. The presence of archaeal amoA genes in Porifera suggests that Archaea are involved in the nitrogen cycle within the sponge holobiont, possibly increasing its resistance to anthropogenic impacts. The higher diversity of Crenarchaeota in the polluted area suggests that some marine sponges are able to change the composition of their associated archaeal communities, thereby improving their fitness in impacted environments.     

Potential Application in Mercury Bioremediation of a Marine Sponge-Isolated Bacillus cereus strain Pj1

Sponges are sessile marine invertebrates that can live for many years in the same location, and therefore, they have the capability to accumulate anthropogenic pollutants such as metals over a long period. Almost all marine sponges harbor a large number of microorganisms within their tissues. The Bacillus cereus strain Pj1 was isolated from a marine sponge, Polymastia janeirensis, and was found to be resistant to 100 μM HgCl₂ and to 10 μM methylmercury (MeHg). Pj1 was also highly resistant to other metals, including CdCl₂ and Pb(NO₃)₂, alone or in combination. The mer operon was located on the bacterial chromosome, and the volatilization test indicated that the B. cereus Pj1 was able to reduce Hg²⁺–Hg⁰. Cold vapor atomic absorption spectrometry demonstrated that Pj1 volatilized 80 % of the total MeHg that it was exposed to and produced elemental Hg when incubated with 1.5 μM MeHg. Pj1 also demonstrated sensitivity to all antibiotics tested. In addition, Pj1 demonstrated a potential for biosurfactant production, presenting an emulsification activity better than synthetic surfactants. The results of this study indicate that B. cereus Pj1 is a strain that can potentially be applied in the bioremediation of HgCl₂ and MeHg contamination in aquatic environments.     

Characterization of Cultivable Bacteria from Brazilian Sponges

Among 1,236 colony-forming units (CFU) associated with 11 species of marine sponges collected from a Brazilian coast, a total of 100 morphologically different bacterial strains were analyzed. The phylogenetic diversity of the bacterial isolates was assessed by 16S rRNA gene amplification—restriction fragment length polymorphism (RFLP) analysis, using AluI restriction endonuclease. The RFLP fingerprinting resulted in 21 different patterns with good resolution for the identification of the bacterial isolates at the genus level. The genus Bacillus was the most commonly encountered genus, followed by Kocuria. Regarding the relationship between the morphotypes and species of marine sponges, Mycale microsigmatosa presented major diversity, followed by Dragmacidon reticulatum and Polymastia janeirensis. An antibiotic susceptibility profile of the 100 sponge-associated bacterial strains was determined by the disk diffusion method, and we observed a variable resistance profile, with 15 % of the bacteria being multiresistant. In addition, 71 of 100 strains were able to produce biofilm. These 71 strains were divided into 20 strong biofilm producers, 10 moderate biofilm producers, and 41 weak biofilm producers. The plasmid profile of the 100 bacterial strains was analyzed and 38 (38 %) of these samples possessed one or more plasmids. Studies like this are important to increase the information on these associated bacteria found off the coastline of Brazil, a place which has rich biodiversity that is still unknown.     

Mercury and methylmercury detoxification potential by sponge-associated bacteria

Ionic and organic forms of mercury (Hg) are powerful cytotoxic and neurotoxic agents in both humans and wild life. The aim of this study was to analyze the resistance profile and potential detoxification of inorganic and organic forms of Hg of bacteria isolated from marine sponges on the coast of Rio de Janeiro, Brazil. Out of the 1,236 colony forming units associated with eleven species of marine sponges, 100 morphologically different bacterial strains were analyzed in this study. Of these, 21 strains were resistant to Hg, 14 of which were classified as highly resistant because they grew despite exposure to 100 µM HgCl₂. Fifteen resistant strains reduced Hg and presented merA in their genomes. The remaining six strains produced biosurfactants, suggesting that they may tolerate Hg by sequestration. Eleven strains grew in the presence of methylmercury. Our results suggest a potential for mercury detoxification by marine sponge-associated resistant bacteria, either through reduction or sequestration, as well as the possibility of bioremediation of toxic waste containing mercury.     

Chemical variability within the marine sponge Aplysina fulva

Dibromotyrosine-derived metabolites are of common occurrence within marine sponges belonging to the order Verongida. However, previous chemical analysis of crude extracts obtained from samples of the verongid sponge Aplysina fulva collected in Brazil did not provide any dibromotyrosine-derived compounds. In this investigation, five samples of A. fulva from five different locations along the Brazilian coastline and one sample from a temperate reef in the South Atlantic Bight (SAB) (Georgia, USA) were investigated for the presence of bromotyrosine-derived compounds. All six samples collected yielded dibromotyrosine-derived compounds, including a new derivative, named aplysinafulvin, which has been identified by analysis of spectroscopic data. These results confirm previous assumptions that dibromotyrosine-derived metabolites can be considered as chemotaxonomic markers of verongid sponges. The isolation of aplysinafulvin provides additional support for a biogenetic pathway involving an arene oxide intermediate in the biosynthesis of Verongida metabolites. It cannot yet be established if the chemical variability observed among the six samples of A. fulva collected in Brazil and the SAB is the result of different environmental factors, distinct chemical extraction and isolation protocols, or a consequence of hidden genetic diversity within the postulated morphological plasticity of this species.     

In vivo study of microsclere formation in sponges of the genus <Emphasis Type="Italic">Mycale</Emphasis> (Demospongiae,Poecilosclerida)

The process of microsclere secretion was examined in vivo through glass coverslip implants in three species of the genus Mycale from São Sebastião channel, southeastern Brazil: Mycale (Aegogropila) angulosa, Mycale (Arenochalina) laxissima, and Mycale (Carmia) microsigmatosa. All three species adhered well to coverslips and developed normally through at least 2 weeks. Similar experiments with different species (Cinachyrella alloclada, Amphimedon viridis, Haliclona melana, and Aplysina caissara) were also successful with one exception (the cartilaginous Chondrilla nucula), indicating that the method can be applied to most demosponges. Microsclerocyte size varied according to the type of microsclere secreted, but all were elongated to fusiform and had small, anucleolated nuclei. Spicules were transported by microsclerocytes alone, without any other cell type ("helper cells") involved. Secretion of a microsclere was performed by a single sclerocyte. Although some axial filaments were found free in the mesohyl, all microsclere secretion in these animals was fully intracellular. Normal axial filaments were observed in most types of microscleres of the Mycale species (sigmas, toxas, and microxeas). Timed observations of sclerocytes suggest that immature spicules with the aspect of short straight rods with thick ends might be the precursors of the anisochelae. Observed differences in the size versus number of toxa secreted may indicate either the presence of two distinct subpopulations of toxa-producing microsclerocytes or that the initial number of axial filaments at the beginning of silica deposition may determine the final size of the spicules. Although other microscleres such as sigmas and chelae are secreted in a one cell-one spicule basis, several toxas and microxeas can be secreted simultaneously in a single cell.     

Frequency distribution of XbaIG > T and HaeIIIT > C <Emphasis Type="Italic">GLUT1</Emphasis> polymorphisms among different Brazilian ethnic groups

GLUT is the major glucose transporter in mammalian cells. Single nucleotide polymorphisms (SNP) at GLUT1 promoter and regulatory regions have been associated to the risk of developing nephropathy in different type 1 and type 2 diabetic populations. It has been demonstrated that differences in allelic and genotypic frequencies of GLUT1 gene (SLC2A1) polymorphisms occur among different populations. Therefore, ethnic differences in distribution of GLUT1 gene polymorphisms may be an important factor in determining gene-disease association. In this study, we investigated the XbaIG > T and HaeIIIT > C polymorphisms in six different Brazilian populations: 102 individuals from Salvador population (Northern Brazil), 56 European descendants from Joinville (South Brazil), 85 Indians from Tiryió tribe (North Brazil) and 127 samples from Southern Brazil: 44 from European descendants, 42 from African descendants and 41 from Japanese descendants. Genotype frequencies from both sites did not differ significantly from those expected under the Hardy–Weinberg equilibrium. We verified that the allele frequencies of both polymorphisms were heterogeneous in these six Brazilian ethnic groups.