Search results for "sponge"
showing 10 items of 296 documents
Morphological Properties of Slender Ca ${\rm{II}}$ H Fibrils Observed by Sunrise II
2017
R. Gafeira et. al.
A little walk between Early Jurassic sponges and corals: a confusing morphological convergence.
2019
24 pages; International audience; Hispaniastraea Turnšek et Geyer, 1975 is a unique coral genus from the Early Jurassic Epoch (Liassic). Corals of this genus are characterised by a highly dominant major septum and a set of eleven minor septa that are very short or even abortive. Initially discovered in Spain, new samples of this genus were depicted from Morocco by Beauvais in 1980; however, this genus was interpreted as a synonym of Pseudoseptifer Fischer, 1970, a chaetetid sponge (i.e., a sponge with siliceous spicules embedded in a calcareous skeleton). The skeleton of Pseudoseptifer is composed of adjacent tubules that increase by fissiparity by means of a pseudoseptum. Based on the stud…
Oxygen microoptodes: a new tool for oxygen measurements in aquatic animal ecology
2002
We describe two applications of a recently introduced system for very precise, continuous measurement of water oxygen saturation. Oxygen microoptodes (based on the dynamic fluorescence quenching principle) with a tip diameter of similar to50 mum, an eight-channel optode array, an intermittent flow system, and online data registration were used to perform two types of experiments. The metabolic activity of Antarctic invertebrates (sponges and scallops) was estimated in respiration experiments, and, secondly, oxygen saturation inside living sponge tissue was determined in different flow regimes. Even in long-term experiments (several days) no drift was detectable in between calibrations. Data…
Mediterranean sponges from shallow subtidal rocky reefs: Cystoseira canopy vs barren grounds
2018
Abstract Porifera richness was investigated in Cystoseira canopies vs barren grounds considering different substrates at 6 areas in the Central-Western Mediterranean Sea. In total 31 sponge taxa were recorded at 2–7 m depth and the sponge community structure and composition were characterized by a notably low richness with 25 taxa in the Cystoseira forest and 15 in the barren area. As for the sponge habitus, the massive sponges were dominant in both facies, whereas encrusting, and cavity dwelling sponges were found in higher numbers in the Cystoseira forest. Results revealed that rocky substrata seem to play a key role in driving the sponge community composition and diversity in both facies…
New Acyclic Cytotoxic Jasplakinolide Derivative from the Marine Sponge Jaspis splendens
2019
A new acylic jasplakinolide congener (2), another acyclic derivative requiring revision (4), together with two jasplakinolide derivatives including the parent compound jasplakinolide (1) were isolated from the Indonesian marine sponge Jaspis splendens. The chemical structures of the new and known compounds were unambiguously elucidated based on HRESIMS and exhaustive 1D and 2D NMR spectral analysis as well as a comparison of their NMR data with those of jasplakinolide (1). The isolated jasplakinolides inhibited the growth of mouse lymphoma (L5178Y) cells in vitro with IC50 values in the low micromolar to nanomolar range.
Hierarchical architecture of sponge spicules: biocatalytic and structure-directing activity of silicatein proteins as model for bioinspired applicati…
2016
Since the first description of the silicateins, a group of enzymes that mediate the formation of the amorphous, hydrated biosilica of the skeleton of the siliceous sponges, much progress has been achieved in the understanding of this biomineralization process. These discoveries include, beside the proof of the enzymatic nature of the sponge biosilica formation, the dual property of the enzyme, to act both as a structure-forming and structure-guiding protein, and the demonstration that the initial product of silicatein is a soft, gel-like material that has to undergo a maturation process during which it achieves its favorable physical-chemical properties allowing the development of various t…
The swinholide biosynthesis gene cluster from a terrestrial cyanobacterium, Nostoc sp. strain UHCC 0450
2017
ABSTRACT Swinholides are 42-carbon ring polyketides with a 2-fold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be the product of a symbiotic heterotrophic proteobacterium. Here, we report the production of swinholide A by an axenic strain of the terrestrial cyanobacterium Nostoc sp. strain UHCC 0450. We located the 85-kb trans -AT polyketide synthase (PKS) swinholide biosynthesis gene cluster from a draft genome of Nostoc sp. UHCC 0450. The swinholide …
Bio-Sintering/Bio-Fusion of Silica in Sponge Spicules
2012
The synthesis of siliceous spicules in both demosponges and hexactinellids is enzymatically driven via silicatein. This enzyme exists both intra-spicularly and in the extra-spicular space. It catalyzes the formation of bio-silica constituting the silica lamellae that are formed during the appositional (layer-by-layer) growth of the spicules. The extent of (bio-silica forming) activity of silicatein from the demosponge Suberites domuncula measured in vitro reflects the amount of bio-silica required for the formation of spicules in vivo. It is shown that during growth and maturation of the spicules in demosponges a bio-fusion process occurs that results in an intra-spicular sintering of the s…
Flashing light in sponges through their siliceous fiber network: A new strategy of “neuronal transmission” in animals
2012
Sponges (phylum Porifera) represent a successful animal taxon that evolved prior to the Ediacaran-Cambrian boundary (542 million years ago). They have developed an almost complete array of cell- and tissue-based interaction systems necessary for the establishment of a functional, multicellular body. However, a network of neurons, one cell/tissue-communication system is missing in sponges. This fact is puzzling and enigmatic, because these animals possess receptors known to be involved in the nervous system in evolutionary younger animal phyla. As an example, the metabotropic glutamate/GABA-like receptor has been identified and cloned by us. Recently, we have identified a novel light transmi…
Genetic, biological and structural hierarchies during sponge spicule formation: from soft sol–gels to solid 3D silica composite structures
2012
Structural biomaterials are hierarchically organized and biofabricated. Although the structural complexity of most bioskeletons can be traced back from the millimeter-scale to the micrometer- or submicrometer-scale, the biological and/or genetic basis controlling the synthesis of these skeletons and their building blocks remained unknown. There is one distinguished example, the spicules of the siliceous sponges, for which the principle molecules and molecular-biological processes involved in their formation have been elucidated in the last few years. In this review, recent data on the different levels of molecular, biological and structural hierarchies controlling the synthesis of the pictu…