Search results for "Rite"
showing 10 items of 2726 documents
Isolation and characterization of two T-box genes from sponges, the phylogenetically oldest metazoan taxon
2003
It is now well established that all metazoan phyla derived from one common ancestor, the hypothetical Urmetazoa. Due to the basal position of Porifera (Demospongiae) in the phylogenetic tree of Metazoa, studies on the mechanisms controlling the development of these animals can provide clues on the understanding of the origin of multicellular animals and on how the first organization of the body plan evolved. In this report we describe the isolation and genomic characterization of two T-box genes from the siliceous sponge Suberites domuncula. The phylogenetic analysis classifies one into the subfamily of Brachyury, Sd-Bra, and the second into the Tbx2 subfamily, Sd-Tbx2. Analyses of the Sd-B…
Species-Specific Aggregation Factor in Sponges
1978
An aggregation receptor (AR) from the siliceous sponge Suberites domuncula has been isolated and purified by chromatography to about 55% purity. The AR consists primarily of neutral carbohydrate and is characterized by a buoyant density of 1.59 g/ml and by an apparent molecular weight of 42,500. The average density of the AR on Suberite cells is about 3.8 × 10 5 per μm 2 . The AR contains considerable amounts of hexuronic acid. The isolated AR can bind not only to receptor-depleted Suberites cells but also to receptor depleted cells from another siliceous species (Geodia cydontum) . After being charged with Suberites ARs, Geodia cells form aggregates in the presence of the species-specific …
Formation of silicones mediated by the sponge enzyme silicatein-α
2010
The sponge-restricted enzyme silicatein-α catalyzes in vivo silica formation from monomeric silicon compounds from sea water (i.e. silicic acid) and plays the pivotal role during synthesis of the siliceous sponge spicules. Recombinant silicatein-α, which was cloned from the demosponge Suberites domuncula (phylum Porifera), is shown to catalyze in vitro condensation of alkoxy silanes during a phase transfer reaction at neutral pH and ambient temperature to yield silicones like the straight-chained polydimethylsiloxane (PDMS). The reported condensation reaction is considered to be the first description of an enzymatically enhanced organometallic condensation reaction.
Molecular Mechanism of Spicule Formation in the Demosponge Suberites domuncula: Silicatein-Collagen-Myotrophin
2003
In living organisms four major groups of biominerals exist: (1) iron compounds, which are restricted primarily to Prokaryota; (2) calcium phosphates, found in Metazoa; (3) calcium carbonates, used by Prokaryota, Protozoa, Plantae, Fungi and Metazoa and (4) silica (opal) present in sponges and diatoms (reviewed in: Bengtson 1994; Baeuerlein 2000). It is surprising that the occurrence of silica as a major skeletal element is restricted to some Protozoa and to sponges (Porifera). The element silicon (Si) contributes to 28% of the earth crust and is - after oxygen - the second most abundant element on earth (Windholz 1983).
A cryptochrome-based photosensory system in the siliceous sponge Suberites domuncula (Demospongiae)
2010
Based on the light-reactive behavior of siliceous sponges, their intriguing quartz glass-based spicular system and the existence of a light-generating luciferase [Muller WEG et al. (2009) Cell Mol Life Sci 66, 537–552], a protein potentially involved in light reception has been identified, cloned and recombinantly expressed from the demosponge Suberites domuncula. Its sequence displays two domains characteristic of cryptochrome, the N-terminal photolyase-related region and the C-terminal FAD-binding domain. The expression level of S. domuncula cryptochrome depends on animal’s exposure to light and is highest in tissue regions rich in siliceous spicules; in the dark, no cryptochrome transcri…
Apposition of silica lamellae during growth of spicules in the demosponge Suberites domuncula: Biological/biochemical studies and chemical/biomimetic…
2006
Recently it has been discovered that the formation of the siliceous spicules of Demospongiae proceeds enzymatically (via silicatein) and occurs matrix guided (on galectin strings). In addition, it could be demonstrated that silicatein, if immobilized onto inorganic surfaces, provides the template for the synthesis of biosilica. In order to understand the formation of spicules in the intact organism, detailed studies with primmorphs from Suberites domuncula have been performed. The demosponge spicules are formed from several silica lamellae which are concentrically arranged around the axial canal, harboring the axial filament composed of silicatein. Now we show that the appositional growth o…
The adaptation of mechanically softened gutta-percha to the canal walls in the presence or absence of smear layer: a scanning electron microscopic st…
1995
Summary The objective of this study was to compare the adaptation of mechanically softened gutta-percha to the root canal wall in the presence and absence of smear layer. The root canals of 20 freshly extracted human maxillary incisors were cleaned and shaped. Prior to obturation, 10 root canals were irrigated with 20 ml of 50% citric acid followed by 20 ml of 5.25% sodium hypochlorite. All canals were obturated with mechanical compaction of gutta-percha and AH-26 sealer. After 72h, each tooth was fractured in half. Scanning electron microscopy demonstrated that the sealer had formed a continuous layer in contact with the canal walls, becoming progressively thinner towards the apex. The sea…
Biological Nutrient Removal Model No. 2 (BNRM2): a general model for wastewater treatment plants
2013
This paper presents the plant-wide model Biological Nutrient Removal Model No. 2 (BNRM2). Since nitrite was not considered in the BNRM1, and this previous model also failed to accurately simulate the anaerobic digestion because precipitation processes were not considered, an extension of BNRM1 has been developed. This extension comprises all the components and processes required to simulate nitrogen removal via nitrite and the formation of the solids most likely to precipitate in anaerobic digesters. The solids considered in BNRM2 are: struvite, amorphous calcium phosphate, hidroxyapatite, newberite, vivianite, strengite, variscite, and calcium carbonate. With regard to nitrogen removal via…
Iekšējās komunikācijas nodrošināšanas novērtējums Rīgas Valda Zālīša sākumskolā
2022
Latvijas Universitātes studentes Ilzes Dzirkales bakalaura darba “Iekšējās komunikācijas nodrošināšanas novērojums Rīgas Valda Zālīša sākumskolā” mērķis ir: pētīt iekšējo komunikāciju Rīgas Valda Zālīša sākumskolā. Bakalaura darbs sastāv no ievada, četrām daļām, secinājumiem un pielikuma. Bakalaura pirmajā daļa darba autore apraksta komunikācijas nozīmi, komunikācijas jēdziena skaidrojumu un komunikācijas mērķus. Bakalaura otrajā daļā apraksta komunikācijas nozīmi organizācijas darbā un starppersonu komunikācijas stilus organizācijas vadītāju darbā. Bakalaura trešajā daļā darba autore apraksta komunikāciju organizācijā un komunikācijas veidus. Veidojot bakalaura teorētisko daļu darba autore…