Search results for "rites"
showing 10 items of 427 documents
Toll-like receptors are part of the innate immune defense system of sponges (demospongiae: Porifera).
2006
During evolution and with the emergence of multicellular animals, the need arose to ward off foreign organisms that threaten the integrity of the animal body. Among many different receptors that participate in the recognition of microbial invaders, toll-like receptors (TLRs) play an essential role in mediating the innate immune response. After binding distinct microbial components, TLRs activate intracellular signaling cascades that result in an induced expression of diverse antimicrobial molecules. Because sponges (phylum Porifera) are filter feeders, they are abundantly exposed to microorganisms that represent a potential threat. Here, we describe the identification, cloning, and deduced …
The onset of the Messinian salinity crisis: Insights from Cyprus sections.
2009
International audience
Origin of the integrin-mediated signal transduction. Functional studies with cell cultures from the sponge Suberites domuncula
1999
Sponges (phylum Porifera) represent the phylogenetically oldest metazoan animals. Recently, from the marine sponge Geodia cydonium a first cDNA encoding a putative integrin receptor molecule was isolated. In the present study basic functional experiments have been conducted to test the hypothesis that in sponges integrin polypeptides also function as adhesion molecules and as outside-in signaling molecules. The sponge Suberites domuncula has been used for the experiments because from this sponge only has a cell culture been established. Here we report that aggregation factor (AF)-mediated cell-cell adhesion is blocked by the RGDS peptide which is known to interact with beta integrin. Both R…
Induction of DNA strand breaks and expression of HSP70 and GRP78 homolog by cadmium in the marine sponge Suberites domuncula
1998
The marine sponge Suberites domuncula was used as a bioindicator to study the effects of cadmium on the occurrence of DNA strand breakage and on the induction of the expression of the stress biomarkers, heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78) homolog. The cDNA encoding GRP78 homolog from S. domuncula was isolated and characterized. The GRP78 cDNA has a length of 2.1 kb and displays characteristic features of the HSP70 family ; it encodes an aa sequence of M-r 72, 000. Exposure of S. domuncula to 1 mg/L of cadmium chloride for 24 h caused a strong(16.6-fold) increase in cadmium content to 7.7 mu g/g wet weight of sponge tissue ; after an incubation period of 6 …
Oxygen-Controlled Bacterial Growth in the Sponge Suberites domuncula: toward a Molecular Understanding of the Symbiotic Relationships between Sponge …
2004
ABSTRACT Sponges (phylum Porifera), known to be the richest producers among the metazoans of bioactive secondary metabolites, are assumed to live in a symbiotic relationship with microorganisms, especially bacteria. Until now, the molecular basis of the mutual symbiosis, the exchange of metabolites for the benefit of the other partner, has not been understood. We show with the demosponge Suberites domuncula as a model that the sponge expresses under optimal aeration conditions the enzyme tyrosinase, which synthesizes diphenols from monophenolic compounds. The cDNA isolated was used as a probe to determine the steady-state level of gene expression. The gene expression level parallels the lev…
Quantification of a novel group of nitrate-reducing bacteria in the environment by real-time PCR
2004
Abstract Nitrate reduction is performed by phylogenetically diverse bacteria. Analysis of narG (alpha subunit of the membrane bound nitrate reductase) trees constructed using environmental sequences revealed a new cluster that is not related to narG gene from known nitrate-reducing bacteria. In this study, primers targeting this as yet uncultivated nitrate-reducing group were designed and used to develop a real-time SYBR® Green PCR assay. The assay was tested with clones from distinct nitrate-reducing groups and applied to various environmental samples. narG copy number was high ranging between 5.08×108 and 1.12×1011 copies per gram of dry weight of environmental sample. Environmental real-…
Arginine kinase in the demosponge Suberites domuncula:regulation of its expression and catalytic activity by silicic acid
2005
SUMMARY In Demospongiae (phylum Porifera) the formation of the siliceous skeleton,composed of spicules, is an energetically expensive reaction. The present study demonstrates that primmorphs from the demosponge Suberites domuncula express the gene for arginine kinase after exposure to exogenous silicic acid. The deduced sponge arginine kinase sequence displays the two characteristic domains of the ATP:guanido phosphotransferases; it can be grouped to the `usual' mono-domain 40 kDa guanidino kinases (arginine kinases). Phylogenetic studies indicate that the metazoan guanidino kinases evolved from this ancestral sponge enzyme; among them are also the `unusual'two-domain 80 kDa guanidino kinas…
Phylogenetic Position of the Hexactinellida Within the Phylum Porifera Based on the Amino Acid Sequence of the Protein Kinase C from Rhabdocalyptus d…
1998
Recent analyses of genes encoding proteins typical for multicellularity, especially adhesion molecules and receptors, favor the conclusion that all metazoan phyla, including the phylum Porifera (sponges), are of monophyletic origin. However, none of these data includes cDNA encoding a protein from the sponge class Hexactinellida. We have now isolated and characterized the cDNA encoding a protein kinase C, belonging to the C subfamily (cPKC), from the hexactinellid sponge Rhabdocalyptus dawsoni. The two conserved regions, the regulatory part with the pseudosubstrate site, the two zinc fingers, and the C2 domain, as well as the catalytic domain were used for phylogenetic analyses. Sequence al…
Acquisition of Structure-guiding and Structure-forming Properties during Maturation from the Pro-silicatein to the Silicatein Form
2012
Silicateins are the key enzymes involved in the enzymatic polycondensation of the inorganic scaffold of the skeletal elements of the siliceous sponges, the spicules. The gene encoding pro-silicatein is inserted into the pCold TF vector, comprising the gene for the bacterial trigger factor. This hybrid gene is expressed in Escherichia coli and the synthesized fusion protein is purified. The fusion protein is split into the single proteins with thrombin by cleavage of the linker sequence present between the two proteins. At 23 °C, the 87 kDa trigger factor-pro-silicatein fusion protein is cleaved to the 51 kDa trigger factor and the 35 kDa pro-silicatein. The cleavage process proceeds and res…
Retinoid X receptor and retinoic acid response in the marine sponge Suberites domuncula
2003
SUMMARY To date no nuclear receptors have been identified or cloned from the phylogenetically oldest metazoan phylum, the Porifera (sponges). We show that retinoic acid causes tissue regression in intact individuals of the demosponge Suberites domuncula and in primmorphs, special three-dimensional cell aggregates. Primmorphs were cultivated on a galectin/poly-L-lysine matrix in order to induce canal formation. In the presence of 1 or 50 μmol l–1 retinoic acid these canals undergo regression, a process that is reversible. We also cloned the cDNA from S. domunculaencoding the retinoid X receptor (RXR), which displays the two motifs of nuclear hormone receptors, the ligand-binding and the DNA-…