A horizontal gene transfer supported the evolution of an early metazoan biomineralization strategy

Background: The synchronous and widespread adoption of the ability to biomineralize was a defining event for metazoan evolution during the late Precambrian/early Cambrian 545 million years ago. However our understanding on the molecular level of how animals first evolved this capacity is poor. Because sponges are the earliest branching phylum of biomineralizing metazoans, we have been studying how biocalcification occurs in the coralline demosponge Astrosclera willeyana. Results: We have isolated and characterized a novel protein directly from the calcified spherulites of A. willeyana. Using three independent lines of evidence (genomic architecture of the gene in A. willeyana, spatial expression of the gene product in A. willeyana and genomic architecture of the gene in the related demosponge Amphimedon queenslandica), we show that the gene that encodes this protein was horizontally acquired from a bacterium, and is now highly and exclusively expressed in spherulite forming cells. Conclusions: Our findings highlight the ancient and close association that exists between sponges and bacteria, and provide support for the notion that horizontal gene transfer may have been an important mechanism that supported the evolution of this early metazoan biomineralisation strategy

Miniaturized biosignature analysis reveals implications for the formation of cold seep carbonates at Hydrate Ridge (off Oregon, USA)

Methane-related carbonates from Hydrate Ridge typically show several macroscopically distinguishable mineral phases, namely whitish aragonite, lucent aragonite, and gray micrite. The relationship of these phases to particular microorganisms or biogeochemical processes is as yet unclear. We used a miniaturized biomarker technique on mg samples, combined with factor analysis and subsequent electron microprobe analysis, to study lipid biomarkers and chemical compositions of the individual phases. This allows us to identify particular mechanisms involved in the formation of the different carbonate precipitates. Our combined analysis of biomarkers and petrographic traits shows that most of the lipids related to the anaerobic oxidation of methane (>90% by weight) are concentrated within only a minor compartment (~20% by volume) of the Hydrate Ridge carbonates, the whitish aragonite. The patterns indicate that the whitish aragonite represents fossilized biofilms of methanotrophic consortia containing mainly archaea of the ANME-2 group and sulfate reducing bacteria, whereas the precipitation of the lucent aragonite may have lacked the immediate proximity of microorganisms during formation. By contrast, the gray micrite formed by incorporation of allochthonous organic and inorganic matter during carbonate precipitation induced by the anaerobic oxidation of methane involving ANME-1 archaea

Spatial patterns in the distribution of benthic assemblages across a large depth gradient in the Coral Sea, Australia

The Queensland Plateau in the Coral Sea off north-eastern Australia supports numerous submerged and emergent reefs. Osprey Reef is an emergent reef at the northern tip of the plateau ~1500 m in elevation. Over such a large depth gradient, a wide range of abiotic factors (e.g. light, temperature, substratum etc.) are likely to influence benthic zonation. Despite the importance of understanding the biodiversity of Australia's Coral Sea, there is a lack of biological information on deep-water habitats below diving depths. Here we used a deep-water ROV transect to capture video, still photos and live samples over a depth range spanning 92 to 787 m at North Horn on Osprey Reef. Video analysis, combined with bathymetry data, was used to identify the zones of geomorphology and the benthic assemblages along the depth gradient. There were marked changes in the geomorphology and the substrate along this depth gradient which likely influence the associated benthos. Cluster analysis indicated five benthic assemblage groups, which showed clear zonation patterns and were generally predictable based on the depth and sedimentary environment. These results are the first quantitative observations to such depths and confirm that the waters of the Coral Sea support diverse benthic assemblages, ranging from shallow-water coral reefs to mesophotic coral ecosystems, to deep-water azooxanthellate corals and sponge gardens. The knowledge provided by our study can inform management plans for the Coral Sea Commonwealth Marine Reserve that incorporate the deeper reef habitats and help to minimise future damage to these marine ecosystems

Estimating the Phanerozoic history of the Ascomycota lineages : Combining fossil and molecular data

Peer reviewe

The cuttlefish Sepia officinalis (Sepiidae, Cephalopoda) constructs cuttlebone from a liquid-crystal precursor

Cuttlebone, the sophisticated buoyancy device of cuttlefish, is made of extensive superposed chambers that have a complex internal arrangement of calcified pillars and organic membranes. It has not been clear how this structure is assembled. We find that the membranes result from a myriad of minor membranes initially filling the whole chamber, made of nanofibres evenly oriented within each membrane and slightly rotated with respect to those of adjacent membranes, producing a helical arrangement. We propose that the organism secretes a chitin-protein complex, which self-organizes layer-by-layer as a cholesteric liquid crystal, whereas the pillars are made by viscous fingering. The liquid crystallization mechanism permits us to homologize the elements of the cuttlebone with those of other coleoids and with the nacreous septa and the shells of nautiloids. These results challenge our view of this ultra-light natural material possessing desirable mechanical, structural and biological properties, suggesting that two self-organizing physical principles suffice to understand its formation.Spanish Ministerio de Ciencia e Innovacion [CGL2010-20748-CO2-01, CGL2013-48247-P, FIS2013-48444-C2-2-P]; Andalusian Consejeria de Innovacion Ciencia y Tecnologia [RNM6433]; (Sepiatech, PROMAR program) of the Portuguese Ministerio da Agricultura e do Mar, Portugal [31.03.05.FEP.002]; Junta de Andalucia [RNM363]; FP7 COST Action of the European Community. [TD0903]info:eu-repo/semantics/publishedVersio

Organomineralization

Encyclopedia of Geobiolog

A relict oasis of living deep-sea mussels Bathymodiolus and microbial-mediated seep carbonates at newly-discovered active cold seeps in the Gulf of Cádiz, NE Atlantic Ocean

Extensive beds of the deep-sea mussel Bathymodiolus mauritanicus (currently also known as Gigantidas mauritanicus) linked to active cold seeps related to fissure-like activity on Al Gacel mud volcano, Gulf of Cádiz, were filmed and sampled for the first time during the oceanographic expedition SUBVENT-2 aboard R/V Sarmiento de Gamboa. Al Gacel mud volcano is one of up to 80 fluid venting submarine structures (mud volcanoes and mud volcano/diapir complexes) identified in the Gulf of Cádiz as result of explosive venting of hydrocarbon-enriched fluids sourced from deep seated reservoirs. This mud volcano is a cone-shaped edifice, 107 m high, 944 m in diameter constituted by mud breccias and, partially covered by pavements of seep carbonates. Extensive beds of this deep-sea mussel were detected at the northern flank at 810–815 m water depth associated with bacterial mats around intermittent buoyant vertical bubble methane plumes. High methane concentrations were measured in the water column above living mussel beds. Other chemosymbiotic species (Siboglinum sp., Solemya elarraichensis, Isorropodon sp., Thyasira vulcolutre and Lucinoma asapheus) were also found in different parts of Al Gacel mud volcano. Al Gacel mud volcano may currently represent one of the most active mud volcanoes in the Gulf of Cádiz, delivering significant amounts of thermogenic hydrocarbon fluids which contribute to foster the extensive chemosynthesis-based communities detected. This finding is of paramount importance for linking extremophile bivalve populations along the North Atlantic, including cold seeps of the Gulf of México, hydrothermal vents of the Mid-Atlantic Ridge and now, detailed documented at the Gulf of Cádiz.Versión del edito

Enemies with benefits: parasitic endoliths protect mussels against heat stress

Positive and negative aspects of species interactions can be context dependant and strongly affected by environmental conditions. We tested the hypothesis that, during periods of intense heat stress, parasitic phototrophic endoliths that fatally degrade mollusc shells can benefit their mussel hosts. Endolithic infestation significantly reduced body temperatures of sun-exposed mussels and, during unusually extreme heat stress, parasitised individuals suffered lower mortality rates than nonparasitised hosts. This beneficial effect was related to the white discolouration caused by the excavation activity of endoliths. Under climate warming, species relationships may be drastically realigned and conditional benefits of phototrophic endolithic parasites may become more important than the costs of infestation

Magnetism, entropy, and the first nano-machines

The efficiency of bio-molecular motors stems from reversible interactions $\sim$ $k_B T$; weak bonds stabilizing intermediate states (enabling $direct$ conversion of chemical into mechanical energy). For their (unknown) origins, we suggest that a magnetically structured phase (MSP) formed via accretion of super-paramagnetic particles (S-PPs) by magnetic rocks on the Hadean Ocean floor had hosted motor-like diffusion of ligand-bound S-PPs through its template-layers; its ramifications range from optical activity to quantum coherence. A gentle flux gradient offers both detailed-balance breaking non-equilibrium and $asymmetry$ to a magnetic dipole, undergoing infinitesimal spin-alignment changes. Periodic perturbation of this background by local H-fields of template-partners can lead to periodic high and low-template affinity states, due to the dipole's magnetic degree of freedom. An accompanying magnetocaloric effect allows interchange between system-entropy and bath temperature. We speculate on a magnetic reproducer in a setting close to the mound-scenario of Russell and coworkers that could evolve bio- ratchets.Comment: 17 pages, 1 figur