The reticuloendothelial system plays a major role in iron metabolism. Despite this, the manner in which macrophages handle iron remains poorly understood. Mammalian cells utilize transferrin-dependent mechanisms to acquire iron via transferrin receptors 1 and 2 (TfR1 and TfR2) by receptor-mediated endocytosis. Here, we show for the first time that the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is localized on human and murine macrophage cell surface. The expression of this surface GAPDH is regulated by the availability of iron in the medium. We further demonstrate that this GAPDH interacts with transferrin and the GAPDHtransferrin complex is subsequently internalized into the early endosomes. Our work sheds new light on the mechanisms involved in regulation of iron, vital for controlling numerous diseases and maintaining normal immune function. Thus, we propose an entirely new avenue for investigation with respect to transferrin uptake and regulation mechanisms in macrophages.Iron is an essential nutrient for all organisms as a constituent of hemoproteins and iron-sulfur proteins. In addition it is also a critical component of functional groups of several proteins involved in vital housekeeping functions. Cells of the immune system require iron for their normal functions such as proliferation, activation, and maturation of lymphocytes (1-5). Iron is also essential for macrophage-mediated cytotoxicity by the production of highly toxic hydroxyl radicals (6, 7). The mononuclear phagocyte system is composed of monocytes, macrophages, and their precursor cells, which play a vital role in iron metabolism by removing effete erythrocytes and recycling iron. These cells also acquire iron via the receptor-mediated uptake of transferrin and the hemoglobin scavenger receptor (8). Practically all extracellular iron circulating in the plasma is bound to transferrin, an abundant protein with high affinity for iron. Two mammalian transferrin receptors TfR1 4 and TfR2 have so far been characterized. Both these receptors are cell surface transmembrane, glycoproteins (9). Unlike TfR1, TfR2 is not regulated by intracellular iron concentrations. This receptor also binds transferrin in manner similar to TfR1, but with a 25-fold lower affinity (10,11,12). Iron uptake from transferrin involves binding to its receptors followed by internalization to the early endosomes. (13, 14). Although TfR-mediated iron uptake is the major pathway for iron acquisition, several studies have indicated that additional mechanisms independent of known TfRs exist; however, these have not been well characterized (15-18). GAPDH was previously considered to be an abundantly present cytosolic protein with a key role in energy metabolism. However, recent evidence has proved that it functions as a moonlighting protein in both prokaryotic and eukaryotic cells, often differentially localized within the cell (19 -21). It is of interest to note that in Staphylococcus aureus, cell wall-associated GAPDH had previously been identified as a trans...
The controlled synthesis of highly crystalline MoS 2 atomic layers remains a challenge for practical applications of this emerging material. We demonstrate a facile method to synthesize crystalline mono-layer / few-layered MoS 2 thin films at liquid-liquid interface which can be suitably transferred on substrates. The films are characterized for its crystal structure by XRD and for the morphology by SEM and TEM. MoS 2 nanosheet-graphene nanosheet (MoS 2 -GNS) hybrid films have been developed by the application of layer-by-layer (LbL) technique. Cyclic voltametry and other electrochemical characterization techniques reveal that the hybrid film electrode shows 10 specific capacitance of 282 Fg -1 at a scan rate of 20 mVs -1 . The as-obtained hybrid electrode is robust and exhibits much improved cycle life (> 1000), retaining over 93 % of its initial capacitance as revealed by galvanostatic charge/discharge studies. The confirmation of better performance as a supercapacitor of the composite was studied by Electrochemical Impedance Spectroscopy. These results indicate that MoS 2 -GNS hybrid is a promising candidate for the electrode material in supercapacitor applications. 15 Chemicals 110All of the reagents used herein were of analytical grade and used as received without any further purification. Molybdenum disulfide (MoS 2 , 99.9%) and graphite rod (99.99 %) were purchased from Sigma-Aldrich Ltd. Conc. Sulfuric acid (H 2 SO 4 , 115 98%), Sodium Sulphate (Na 2 SO 4 ) and oleic acid (99% by GC)
Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 andn-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5–15 nm) as compared to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that of colloidal sulfur.
Co3O4, which crystallizes in the spinel phase at temperatures much higher than ambient temperatures, orders antiferromagnetically below its Neel temperature (∼40 K). However, in nanosize, it shows ferromagnetic ordering due to surface canting, disorder, imperfect oxygen atom coordination, etc. Here, for the first time, we report the synthesis of single-crystalline, ferromagnetic Co3O4 nanoparticles functionalized with proteins (size 5–7 nm) using cobalt acetate as precursor at room temperature in aqueous medium by a metal-tolerant marine bacterium isolated from the coast of the Arabian Sea. Energetically unfavorable change in the oxidation state of Co atoms from (+2 to +3) during synthesis by the bacterial strain was evidenced by X-ray photoelectron spectroscopy. The effect on the morphology of bacterial cells after exposure to the cobalt acetate was imaged by scanning electron microscopy showing cooperative, self-organized, structured colony formation, possibly due to the interbacterial communication under external stress.
Oriented attachment is a new way of crystal growth to transform preformed nanoparticles into hierarchical assemblies. Here, we demonstrate the use of liquid-liquid interfaces toward the formation of PbCrO 4 nanoparticles and their subsequent time-dependent self-assembly at the air-water interface into nanorods by oriented attachment. EDAX and XPS analysis indicate the formation of stoichiometric PbCrO 4 . TEM studies at different stages of aging reveal that the transformation from nanoparticles to nanorods is kinetically governed. HRTEM analysis indicates nanorod growth along the [110] plane. UV-visible spectra reveal the presence of peaks at 425 and 515 nm for nanorods, while for the nanoparticle sample, a single peak at 425 nm is evident. As formation of ultrathin films over a large area (typically equal to or greater than 1µm × 1µm) concomitantly accompanies this approach, it can be extended to other materials as well for nanostructured device applications.
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