Search results for "Transmembrane"
showing 9 items of 299 documents
In Vitro Cytotoxic Effect of Aqueous Extracts from Leaves and Rhizomes of the Seagrass Posidonia oceanica (L.) Delile on HepG2 Liver Cancer Cells: Fo…
2023
Aqueous extracts from Posidonia oceanica’s green and brown (beached) leaves and rhizomes were prepared, submitted to phenolic compound and proteomic analysis, and examined for their potential cytotoxic effect on HepG2 liver cancer cells in culture. The chosen endpoints related to survival and death were cell viability and locomotory behavior, cell-cycle analysis, apoptosis and autophagy, mitochondrial membrane polarization, and cell redox state. Here, we show that 24 h exposure to both green-leaf- and rhizome-derived extracts decreased tumor cell number in a dose–response manner, with a mean half maximal inhibitory concentration (IC50) estimated at 83 and 11.5 μg of dry extract/mL, respecti…
Biological and Proteomic Characterization of the Anti-Cancer Potency of Aqueous Extracts from Cell-Free Coelomic Fluid of Arbacia lixula Sea Urchin i…
2022
Echinoderms are an acknowledged source of bioactive compounds exerting various beneficial effects on human health. Here, we examined the potential in vitro anti-hepatocarcinoma effects of aqueous extracts of the cell-free coelomic fluid obtained from the sea urchin Arbacia lixula using the HepG2 cell line as a model system. This was accomplished by employing a combination of colorimetric, microscopic and flow cytometric assays to determine cell viability, cell cycle distribution, the possible onset of apoptosis, the accumulation rate of acidic vesicular organelles, mitochondrial polarization, cell redox state and cell locomotory ability. The obtained data show that exposed HepG2 cells under…
Mathematical modelling of Membrane Bioreactors
2015
Mathematical modelling of membrane bioreactors (MBRs) for wastewater treatment has targeted either the biological processes (treatment quality target) as well as various aspects of system management. However, the high number of interactions among the involved physical – chemical processes, hampers a straightforward mathematical modelling. This circumstance is much more emphasized for submerged MBR systems where the membrane is immersed in an aeration tank. One of the main crucial point that prevents a comprehensive understanding is the interpretation of the fouling phenomenon and its connections with the biological processes. An overall mathematical model for MBR has not been completely est…
Cytotoxic necrotizing factor type 2 produced by virulent Escherichia coli modifies the small GTP-binding proteins Rho involved in assembly of actin s…
1994
Cytotoxic necrotizing factor type 2 (CNF2) produced by Escherichia coli strains isolated from intestinal and extraintestinal infections is a dermonecrotic toxin of 110 kDa. We cloned the CNF2 gene from a large plasmid carried by an Escherichia coli strain isolated from a lamb with septicemia. Hydropathy analysis of the deduced amino acid sequence revealed a largely hydrophilic protein with two potential hydrophobic transmembrane domains. The N-terminal half of CNF2 showed striking homology (27% identity and 80% conserved residues) to the N-terminal portion of Pasteurella multocida toxin. Methylamine protection experiments and immunofluorescence studies suggested that CNF2 enters the cytosol…
Comparison of a MBR system start-up with and without inoculum: experimental and mathematical model application
2010
The performance of a membrane bioreactor (MBR) system and the extension and mechanisms that lead to the formation of the fouling may differ in relation to the start-up. As a consequence, the MBR start-up may constitute a crucial point that drastically influence the MBR performance in its lifespan. Indeed, the start-up influences the mechanisms of membrane fouling whose effects, in the case of irreversible cake deposition, can be modified only by a chemical membrane washing. In order to gain insights about the effect of the start-up on a MBR system, a MBR pilot plant was build-up and a mathematical model developed. The MBR system was constituted by a hollow fibre membrane module installed in…
A model for wastewater organic removal and fouling development in a SMBR pilot plant
2007
The paper presents the setting up of a mathematical model for membrane bioreactor able to simulate physical-biological wastewater organic removal. The model is basically divided into two sub-models: the first sub-model is basically devoted for the simulation of the biological features and the second one for the physical processes. In particular regarding the biological aspects, the ASM concept has been employed. On the other hand, the physical processes have been modelled considering the deep-bed theory taking into account not only the effect of the physical membrane filtration but also the cake layer effect. This latter operates as a biological membrane leading to a further reduction of th…
Properties of transmembrane helix TM1 of the DcuS sensor kinase of Escherichia coli, the stator for TM2 piston signaling
2021
Abstract The sensor kinase DcuS of Escherichia coli perceives extracellular fumarate by a periplasmic PASP sensor domain. Transmembrane (TM) helix TM2, present as TM2-TM2′ homo-dimer, transmits fumarate activation in a piston-slide across the membrane. The second TM helix of DcuS, TM1, is known to lack piston movement. Structural and functional properties of TM1 were analyzed. Oxidative Cys-crosslinking (CL) revealed homo-dimerization of TM1 over the complete membrane, but only the central part showed α-helical +3/+4 spacing of the CL maxima. The GALLEX bacterial two-hybrid system indicates TM1/TM1′ interaction, and the presence of a TM1-TM1′ homo-dimer is suggested. The peripheral TM1 regi…
Lipid Binding Controls Dimerization of the Coat Protein p24 Transmembrane Helix
2019
Abstract Coat protein (COP) I and COP II complexes are involved in the transport of proteins between the endoplasmic reticulum and the Golgi apparatus in eukaryotic cells. The formation of COP I/II complexes at membrane surfaces is an early step in vesicle formation and is mastered by p24, a type I transmembrane protein. Oligomerization of p24 monomers was suggested to be mediated and/or stabilized via interactions within the transmembrane domain, and the p24 transmembrane helix appears to selectively bind a single sphingomyelin C18:0 molecule. Furthermore, a potential cholesterol-binding sequence has also been predicted in the p24 transmembrane domain. Thus, sphingomyelin and/or cholestero…
The AQP2 mutation V71M causesnephrogenic diabetes insipidus in humans but does not impair the function of a bacterial homolog
2015
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