The generation of reactive oxygen species (ROS) is an important mechanism of nanomaterial toxicity. We found that Prussian blue nanoparticles (PBNPs) can effectively scavenge ROS via multienzyme-like activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) activity. Instead of producing hydroxyl radicals (•OH) through the Fenton reaction, PBNPs were shown to be POD mimetics that can inhibit •OH generation. We theorized for the first time that the multienzyme-like activities of PBNPs were likely caused by the abundant redox potentials of their different forms, making them efficient electron transporters. To study the ROS scavenging ability of PBNPs, a series of in vitro ROS-generating models was established using chemicals, UV irradiation, oxidized low-density lipoprotein, high glucose contents, and oxygen glucose deprivation and reperfusion. To demonstrate the ROS scavenging ability of PBNPs, an in vivo inflammation model was established using lipoproteins in Institute for Cancer Research (ICR) mice. The results indicated that PBNPs hold great potential for inhibiting or relieving injury induced by ROS in these pathological processes.
Ten to twenty percent of newly diagnosed glioblastoma (GBM) patients initially present with multiple lesions, termed multifocal or multicentric GBM (M-GBM). The prognosis of these patients is poorer than is that of solitary GBM (S-GBM) patients. However, it is unknown whether multifocality has a genetic, epigenetic, or molecular basis. Here, we identified the genetic and epigenetic characteristics of M-GBM by performing a comprehensive analysis of multidimensional data, including imaging, genetic, epigenetic, and gene expression profiles, from 30 M-GBM cases in The Cancer Genome Atlas (TCGA) database and comparing the results with those of 173 S-GBM cases. We found that M-GBMs had no IDH1, ATRX, or PDGFRA mutations and were significantly associated with the mesenchymal subtype. We also identified the CYB5R2 gene to be hypo-methylated and overexpressed in M-GBMs. The expression level of CYB5R2 was significantly associated with patient survival in two major independent GBM cohorts, totaling 758 cases. The IDH1 mutation was markedly associated with CYB5R2 promoter methylation, but the survival influence of CYB5R2 was independent of IDH1 mutation status. CYB5R2 expression was significantly associated with collagen maturation and the catabolic process and immunoregulation pathways. These results reveal that M-GBMs have some underlying genetic and epigenetic characteristics that are associated with poor prognosis and that CYB5R2 is a new epigenetic marker for GBM prognosis.
Hydroxybenzoic acid esters (parabens) are used as preservatives in foods, cosmetics, and pharmaceuticals, which results in the exposure of humans to these compounds. Parabens and its metabolite, p-hydroxybenzoic acid (p-HB) are excreted from urine in free and conjugated forms. In this study, free and total forms (free plus conjugated) of parabens and their common metabolite, p-HB, were measured in urine samples collected from U.S. children (n = 40), Chinese children (n = 70), and Chinese adults (n = 26). The median concentrations of the sum of 6 parabens (Σparabens) in urine from U.S. and Chinese children were 54.6 and 10.1 ng/mL, respectively. The median concentration of urinary parabens measured for Chinese adults was 33.2 ng/mL, which was lower than that reported for U.S. adults. Elevated concentrations of parabens (1000-10,000 ng/mL) were found in urine from some Chinese adult females. Parabens were present predominantly (>90%) as conjugated species in urine. Among the six parabens analyzed, methyl paraben (MeP) and propyl paraben (PrP) were the predominant compounds, which accounted for 57-98% and 1.4-12%, respectively, of the total concentrations. A significant positive correlation was found between the concentrations of MeP and PrP. The geometric mean (GM) concentration of p-HB was 1380 and 2370 ng/mL for Chinese children and adults, respectively. The GM concentrations of p-HB in urine from U.S. children were 752 ng/mL for girls and 628 ng/mL for boys, which were 2-3 times lower than the concentrations determined for Chinese children. There was a significant difference in the ratios of concentrations of Σparabens and p-HB between demographic groups, which suggested the existence of various exposure routes to parabens. Based on the concentrations of urinary parabens and p-HB, the daily intake (DI) of MeP and PrP was estimated. The GM DI(MeP) estimated for Chinese children was 0.5-0.7 mg/day, which was similar to those determined for U.S. children. The GM DI(PrP) (0.2-0.5 mg/day) estimated for Chinese children was 20- to 50-fold higher than the value determined for U.S. children (0.01 mg/day). The highest exposure to parabens was found for Chinese adult females, with GM DI(MeP) and DI(PrP) of 5.9 and 1.2 mg/day, respectively. Elevated exposure to PrP was found in some Chinese adult females (27 mg/day) and children (11 mg/day).
Research funding is provided by the Ministry of Science and Technology of China [2012CB944704; 2012CB966702], the National Natural Science Foundation of China [Grant number: 31171429] and Beijing Advanced Innovation Center for Structural Biology. The authors declare no conflict of interest.
RNA editing is the post-transcriptional conversion from C to U before translation, providing a unique feature in the regulation of gene expression. Here, we used a robust and efficient method based on RNA-seq from non-ribosomal total RNA to simultaneously measure chloroplast-gene expression and RNA editing efficiency in the Greater Duckweed, Spirodela polyrhiza, a species that provides a new reference for the phylogenetic studies of monocotyledonous plants. We identified 66 editing sites at the genome-wide level, with an average editing efficiency of 76%. We found that the expression levels of chloroplast genes were relatively constant, but 11 RNA editing sites show significant changes in editing efficiency, when fronds turn into turions. Thus, RNA editing efficiency contributes more to the yield of translatable transcripts than steady state mRNA levels. Comparison of RNA editing sites in coconut, Spirodela, maize, and rice suggests that RNA editing originated from a common ancestor.
BACKGROUND Hydrogen sulfide (H2S) is a known signaling molecule in plants, which has the ability to delay fruit ripening. Our previous studies have shown that H2S treatment could delay the maturation of kiwifruits by inhibiting ethylene production, improving protective enzyme activities, and decreasing the accumulation of reactive oxygen species to protect the cell membrane during storage. The mechanism related to the way in which H2S affected kiwifruit maturation was still unclear. We performed transcriptome sequencing to explore the influences of H2S on the softening of kiwifruit. RESULTS The firmness and the soluble solids content (SSC) of the kiwifruit were significantly better maintained with H2S treatment compared to the control during the storage period (P < 0.05). Transmission electron microscopy (TEM) showed that degradation of the cell wall was inhibited after H2S treatment. Based on transcriptome data analysis and quantitative real‐time polymerase chain reaction (qRT‐PCR), expression levels of endo‐1,4‐β‐glucanase (β‐glu), β‐galactosidase (β‐gal) and pectinesterase (PME) decreased whereas pectinesterase inhibitor (PMEI) significantly increased in response to H2S. The members of the signal transduction pathway involved in ethylene were also identified. Hydrogen sulfide inhibited the expression of ethylene receptor 2 (ETR2), ERF003, ERF5, and ERF016, and increased the expression of ethylene‐responsive transcription factor 4 (ERF4) and ERF113. CONCLUSION Hydrogen sulfide could delay the ripening and senescence of kiwifruit by regulating the cell‐wall degrading enzyme genes and affecting ethylene signal transduction pathway genes. Our results revealed the effect of H2S treatment on the softening of kiwifruit at the transcription level, laying a foundation for further research. © 2020 Society of Chemical Industry
This work investigates the role of hydrogen sulfide (H2S) in the browning and regulating the antioxidant defensive system in fresh-cut Chinese water chestnuts. The samples were fumigated with 0, 10, and 15 μl L−1 of H2S and stored at 10°C for 8 days. The results indicated that the H2S treatment significantly inhibited the browning of fresh-cut Chinese water chestnuts, reduced superoxide anion (O2·-) production rate and H2O2 content accumulation, promoted the increase of total phenol content, and enhanced activities of catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) (P < 0.05). On the other hand, phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) activities remained at a low level in the H2S treatment (P < 0.05). This result suggested that H2S treatment might be a promising approach to inhibit browning and prolong the shelf life by enhancing oxidation resistance and inhibiting browning enzyme activity of fresh-cut Chinese water chestnuts during storage. Among them, the 15 μl L−1 H2S treatment had the best effect on fresh-cut Chinese water chestnuts.
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