Genomic insights into the marine sponge microbiome

Marine sponges (phylum Porifera) often contain dense and diverse microbial communities, which can constitute up to 35% of the sponge biomass. The genome of one sponge, Amphimedon queenslandica, was recently sequenced, and this has provided new insights into the origins of animal evolution. Complementary efforts to sequence the genomes of uncultivated sponge symbionts have yielded the first glimpse of how these intimate partnerships are formed. The remarkable microbial and chemical diversity of the sponge-microorganism association, coupled with its postulated antiquity, makes sponges important model systems for the study of metazoan host-microorganism interactions, and their evolution, as well as for enabling access to biotechnologically important symbiont-derived natural products. In this Review, we discuss our current understanding of the interactions between marine sponges and their microbial symbiotic consortia, and highlight recent insights into these relationships from genomic studies.     

Lipidomics of the sea sponge Amphimedon queenslandica and implication for biomarker geochemistry

Demosponges are a rich natural source of unusual lipids, some of which are of interest as geochemical biomarkers. Although demosponges are animals, they often host dense communities of microbial symbionts, and it is therefore unclear which lipids can be synthesized by the animal de novo, and which require input from the microbial community. To address this uncertainty, we analyzed the lipids of Amphimdeon queenslandica, the only demosponge with a published genome. We correlated the genetic and lipid repertoires of A. queenslandica to identify which biomarkers could potentially be synthesized and/or modified by the sponge. The fatty acid profile of A. queenslandica is dominated by an unusual Δ^5,9 fatty acid (cis‐5,9‐hexacosadienoic acid)—similar to what has been found in other members of the Amphimdeon genus—while the sterol profile is dominated by C₂₇‐C₂₉ derivatives of cholesterol. Based on our analysis of the A. queenslandica genome, we predict that this sponge can synthesize sterols de novo, but it lacks critical genes necessary to synthesize basic saturated and unsaturated fatty acids. However, it does appear to have the genes necessary to modify simpler products into a more complex “algal‐like” assemblage of unsaturated fatty acids. Ultimately, our results provide additional support for the poriferan affinity of 24‐isopropylcholestanes in Neoproterozoic‐age rocks (the “sponge biomarker” hypothesis) and suggest that some algal proxies in the geochemical record could also have animal contributions.     

Pathologic diagnosis of breast cancer patients: evolution of the traditional clinical-pathologic paradigm toward “precision” cancer therapy

We present an updated account of breast cancer treatment and of progress toward “precision” cancer therapy; we focus on new developments in diagnostic molecular pathology and breast cancer that have emerged during the past 2 years. Increasing awareness of new prognostic and predictive methodologies, and introduction of next generation sequencing has increased understanding of both tumor biology and clinical behavior, which offers the possibility of more appropriate therapeutic choices. It remains unclear which of these testing methodologies provides the most informative and cost-effective actionable results for predictive and prognostic pathology. It is likely, however, that an integrated “step-wise” approach that uses the traditional clinical-pathologic paradigms coordinated with molecular characterization of breast tumor tissue, will offer the most comprehensive and cost-effective options for individualized, “precision” therapy for patients with breast cancer.     

The stress responsive and morphologically regulated <Emphasis Type="Italic">hsp90</Emphasis> gene from <Emphasis Type="Italic">Paracoccidioides brasiliensis</Emphasis> is essential to cell viability

Background  

Paracoccidioides brasiliensis is a dimorphic fungus that causes the most prevalent systemic mycosis in Latin America. The response to heat shock is involved in pathogenesis, as this pathogen switches from mycelium to yeast forms in a temperature dependent fashion that is essential to establish infection. HSP90 is a molecular chaperone that helps in the folding and stabilization of selected polypeptides. HSP90 family members have been shown to present important roles in fungi, especially in the pathogenic species, as an immunodominant antigen and also as a potential antifungal therapeutic target.     

Evolutionary genetics of a defensive facultative symbiont of insects: exchange of toxin-encoding bacteriophage

The facultative endosymbiont of aphids, Hamiltonella defensa , kills parasitoid wasp larvae, allowing aphid hosts to survive and reproduce. This protection may depend on toxins that are encoded by the genomes of H. defensa and of its bacteriophage (APSE). Strains of H. defensa vary in degree of protection conferred upon Acyrthosiphon pisum (pea aphid). Although H. defensa is known to undergo some horizontal transmission among aphid maternal lineages, divergence, recombination, and population structure in H. defensa and APSE have not been characterized. We performed a multilocus sequence analysis of 10 bacterial and five phage loci for strains isolated from A. pisum and other aphid species. The H. defensa chromosome was found to be largely clonal, allowing us to generate a well-resolved H. defensa strain phylogeny. In contrast, APSE chromosomes undergo recombination and numerous H. defensa strains have probably lost the phage. Within a set of H. defensa strains that are indistinguishable on the basis of chromosomal genes or restriction digests of chromosomal fragments, loss of APSE is associated with decreased protection, strongly suggesting that APSE-encoded genes contribute to the defensive phenotype. Thus, homologous recombination of APSE genes and sexual transmission of symbionts and phage are likely factors influencing the exchange of ecologically important genes among symbionts. Although H. defensa has been lost, transferred and gained within A. pisum , one subclade of H. defensa appears to be universal within a subclade of the aphid genus Uroleucon , suggesting a transition from facultative, horizontal transmission to strictly vertical inheritance.     

Inhibition of settlement and metamorphosis of the ascidian Herdmania curvata by non-geniculate coralline algae

The surfaces of non-geniculate coralline algae (NCA) are known to induce the settlement and metamorphosis of disparate marine taxa. In this study we investigate the responsiveness of larvae of Herdmania curvata (Ascidiacea: Stolidobranchia) to three species of NCA (Neogoniolithon brassica-florida, Hydrolithon onkodes, and Lithothamnium prolifer) that cohabit the slope and crest of Heron Reef, Great Barrier Reef. H. curvata larvae were first exposed to these NCA at or within 2 h of hatching, which is 1 to 2 h prior to attaining competence, and then cultured continuously with the NCA for 12 to 14 h. Rates of settlement and metamorphosis of H. curvata cultured in laboratory chambers in the presence of the different NCA were significantly lower than spontaneous rates in seawater. The limited settlement in treatments containing NCA were confined entirely to the chamber periphery, and settlement never occurred on the surface of the NCA. The inhibitory effect was dose-dependent and was stronger in N. brassica-florida and H. onkodes than in L. prolifer. Larvae that did not settle in treatments with NCA had rounded anterior trunks and, in extreme cases, kinked tails with rounded and dissociated tail muscle cells. In some individuals, we observed the anterior chemosensory papillae being sloughed off the larval body. Morphological analysis of trunk ectodermal and mesenchymal nuclei of larvae cultured in the presence of the NCA revealed that general necrotic cell death was occurring. Importantly, H. curvata larvae that were exposed to NCA could not subsequently be induced to metamorphose in KCl-elevated seawater, whereas larvae not exposed to NCA metamorphosed at high rates in KCl-elevated seawater.