Ferritins are the main iron storage proteins found in animals, plants, and bacteria. The capacity to store iron in ferritin is essential for life in mammals, but the mechanism by which cytosolic iron is delivered to ferritin is unknown. Human ferritins expressed in yeast contain little iron. Human Poly r(C)-Binding Protein 1 (PCBP1) increased the amount of iron loaded into ferritin when expressed in yeast. PCBP1 bound to ferritin in vivo, and bound iron and facilitated iron loading into ferritin in vitro. Depletion of PCBP1 in human cells inhibited ferritin iron loading and increased cytosolic iron pools. Thus, PCBP1 can function as a cytosolic iron chaperone in the delivery of iron to ferritin.Ferritins are iron storage proteins that are ubiquitously expressed in animals, plants, and bacteria. They serve both to sequester excess iron taken up by the cell and to release stored iron to meet the cell's metabolic needs during iron scarcity (1). In animals, ferritin is a cytosolic heteropolymer consisting of 24 subunits of H-and L-isoforms that assemble into a hollow sphere into which iron is deposited. Ferritin H-chains contain the iron-binding and ferroxidase activities that are required for mineralization of the ferritin core. Deletion of the H-ferritin gene is lethal in mice (2) and in flies (3).In cells, metallochaperones deliver metals to their cognate enzymes and transporters. Although cytosolic copper and nickel chaperones have been described (4-7), no cytosolic iron chaperones have been identified, despite the presence of numerous iron-dependent enzymes in the cytosol. Frataxin, the protein lacking in the neurological disease Friedreich's ataxia, functions as a mitochondrial iron chaperone for iron-sulfur cluster and heme biosynthesis (8,9).Fungi are anomalous among eukaryotes in that they do not express ferritins. We expressed human H-and L-ferritins in the yeast Saccharomyces cerevisiae. The peptides assembled into multimeric complexes with properties similar to native human ferritins, but contained only small amounts of iron ( fig. S1, A and B). We hypothesized that yeast might also lack the requisite iron chaperones needed for delivery of iron to ferritin and designed a genetic screen to identify human genes that, when expressed in yeast, could increase the amount of iron loaded into ferritin. We introduced an iron-regulated FeRE/HIS3 reporter construct (10) into a yeast strain expressing H-and L-ferritin (Fig. 1A). This construct confers histidine prototrophy to cells when the reporter is bound and transcriptionally activated by Aft1p, the major irondependent transcription factor in yeast. Aft1p is activated during periods of cytosolic iron depletion (11), which could occur if substantial amounts of cytosolic iron were diverted into ferritin. †To whom correspondence should be addressed.

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Data normalization is essential for reliable output of quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) assays, as the unsuitable choice of reference gene(s), whose expression might be influenced by exogenous treatments in plant tissues, could cause misinterpretation of results. To date, no systematic studies on reference genes have been performed in stressed Brassica napus. In this study, we investigated the expression variations of nine candidate reference genes in 40 samples of B. napus leaves subjected to various exogenous treatments. Parallel analyses by geNorm and NormFinder revealed that optimal reference genes differed across the different sets of samples. The best-ranked reference genes were PP2A and TIP41 for salt stress, TIP41 and ACT7 for heavy metal (Cr(6+)) stress, PP2A and UBC21 for drought stress, F-box and SAND for cold stress, F-box and ZNF for salicylic acid stress, TIP41, ACT7, and PP2A for methyl jasmonate stress, TIP41 and ACT7 for abscisic acid stress, and TIP41, UBC21, and PP2A for Sclerotinia sclerotiorum stress. Two newly employed reference genes, TIP41 and PP2A, showed better performances, suggesting their suitability in multiple conditions. To further validate the suitability of the reference genes, the expression patterns of BnWRKY40 and BnMKS1 were studied in parallel. This study is the first systematic analysis of reference gene selection for qRT-PCR normalization in B. napus, an agriculturally important crop, under different stress conditions. The results will contribute toward more accurate and widespread use of qRT-PCR in gene analysis of the genus Brassica.

A simple and low-energy-consuming approach to synthesize highly stable and dispersive silver nanoparticle-graphene (AgNP-GE) nanocomposites has been developed, in which the stability and dispersivity of the composites are varied greatly with the pH value and temperature of the reaction. The results demonstrate that the optimal reaction conditions are pH 11 at room temperature for 70 min. As-synthesized composites display excellent antimicrobial activity, and can completely inhibit the growth of Escherichia coli cells at a concentration of 20 mg L(-1) (20 ppm). After treatment with 10 ppm AgNP-GE composites, the cells are killed completely within 3 h. The unique structure imparts such good antimicrobial properties to the composites. Firstly, the sheetlike AgNP-GE tends to be adsorbed and accumulated onto the surface of cells, which can change the permeability and enhance the antimicrobial activity. Secondly, Ag(+) released from AgNPs can act on the cells effectively and fully, thereby resulting in cell death.

In recent years, researchers have proven the release of silver ions (Ag(+)) from silver nanoparticles (Ag NPs) significantly affects their toxicity to bacteria and other organisms. Due to the difficulty in maintaining a steady flux of a high concentration of Ag(+), it is still challenging to develop a highly efficient, stable, and biocompatible Ag NP-based antimicrobial material. To circumvent this issue, we developed a new Ag-based bactericide through the fabrication of sunlight-driven and ultrafine silver/silver chloride anchored on reduced graphene oxide (Ag/AgCl/rGO). This stable Ag/AgCl nanophotocatalyst with negligible release of Ag(+) generated a high amount of oxidative radicals, killing the bacteria, thus achieving both high bactericidal efficiency and stability. Moreover, functionalization of the nanomaterial with poly(diallyldimethylammonium chloride) (PDDA) gives it a highly adsorptive capacity, which allows it to capture the bacteria and possibly enhances the bactericidal activity. In vivo histopathological studies showed that the Ag/AgCl/rGO nanomaterial could obviously promote the regeneration of the epidermis, which indicated the good biomedical potential of Ag/AgCl/rGO nanomaterial in burn wound healing.

Proinflammatory cytokines play a key role in the pathophysiology of muscle atrophy. In addition, n3 polyunsaturated fatty acids (PUFAs) exert an inhibitory effect on proinflammatory cytokines affecting many inflammatory diseases. We hypothesized that dietary supplementation of fish oil could attenuate lipopolysaccharide (LPS)-induced muscle atrophy. Weanling pigs were used in a 2 × 2 factorial design and the main factors included diet (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline). After 21 d of treatment with either fish oil or corn oil, pigs received an i.p. injection of either saline or LPS. At 4 h postinjection, blood and muscle samples were obtained. Fish oil led to enrichment of eicosapentaenoic acid, docosahexaenoic acid, and total n3 PUFAs in muscles. Fish oil increased muscle protein mass, indicated by a higher protein:DNA ratio in gastrocnemius and longissimus dorsi (LD) muscles. In addition, fish oil increased Akt1 mRNA abundance and decreased Forkhead Box O (FOXO) 1 and FOXO4 mRNA abundance. Fish oil also increased phosphorylation of Akt and FOXO1 in gastrocnemius and LD muscles. Fish oil decreased the mRNA abundance of muscle atrophy F-box (MAFbx) and muscle RING finger 1 in gastrocnemius and LD muscles. Moreover, fish oil reduced the plasma tumor necrosis factor (TNF) α, muscle TNFα, and prostaglandin E2 concentrations, and muscle TNFα and cyclooxygenase 2 (COX2) mRNA abundance. Finally, fish oil downregulated the mRNA abundance of muscle toll-like receptor (TLR4) and its downstream signaling molecules [myeloid differentiation factor 88 (MyD88), TNFα receptor-associated factor 6 (TRAF6), and NF-κB p65], and nucleotide-binding oligomerization domain protein (NOD1), NOD2, and their adaptor molecule [receptor-interacting serine/threonine-protein kinase 2 (RIPK2)]. These results indicate fish oil may suppress muscle proinflammatory cytokine production via regulation of TLR and NOD signaling pathways and therefore improve muscle protein mass, possibly through maintenance of Akt/FOXO signaling.

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