RESUMO
Developing quantification and characterization methodology for metallic nanoparticles (MNPs) and their ionic component in complex matrix are crucial for the evaluation of their environmental behavior and health risks to humans. In this study, reversed phase high performance liquid chromatography combined ICP-MS was established for the characterization of MNPs in complex matrix. The ionic component could be separated from NPs with the optimized parameters of aqueous mobile phase. Good linear relationship between average diameter and retention time of NPs was obtained using HPLC-ICP-MS and the size smaller than 40â¯nm could be determined with this method, the detected results were in accordance with TEM results. The low detection limit of AuNPs and Au(â ¢) (both in sub-µg/L level) showed that this method was promising for the characterization of AuNPs and Au(â ¢) in environmental water. The mass concentration of ionic Au(â ¢) in environmental water could be detected using the proposed HPLC-ICP-MS and the concentration of AuNPs was obtained by subtracting the Au(â ¢) concentration from the total Au (The concentration of total Au was detected by ICP-MS after microwave digestion). Furthermore this proposed HPLC-ICP-MS method and single particle-ICPMS (SP-ICP-MS) was used for the analysis of the Ag speciation in commercial antibacterial products.
Assuntos
Poluentes Ambientais/química , Ouro/isolamento & purificação , Nanopartículas Metálicas/análise , Platina/isolamento & purificação , Prata/isolamento & purificação , Cátions , Cromatografia de Fase Reversa/métodos , Água Potável/química , Água Doce/química , Humanos , Limite de Detecção , Espectrometria de Massas por Ionização por Electrospray/métodosRESUMO
piRNAs are critical for transposable element (TE) repression and germ cell survival during the early phases of spermatogenesis, however, their role in adult germ cells and the relative importance of piRNA methylation is poorly defined in mammals. Using a mouse model of HEN methyltransferase 1 (HENMT1) loss-of-function, RNA-Seq and a range of RNA assays we show that HENMT1 is required for the 2' O-methylation of mammalian piRNAs. HENMT1 loss leads to piRNA instability, reduced piRNA bulk and length, and ultimately male sterility characterized by a germ cell arrest at the elongating germ cell phase of spermatogenesis. HENMT1 loss-of-function, and the concomitant loss of piRNAs, resulted in TE de-repression in adult meiotic and haploid germ cells, and the precocious, and selective, expression of many haploid-transcripts in meiotic cells. Precocious expression was associated with a more active chromatin state in meiotic cells, elevated levels of DNA damage and a catastrophic deregulation of the haploid germ cell gene expression. Collectively these results define a critical role for HENMT1 and piRNAs in the maintenance of TE repression in adult germ cells and setting the spermatogenic program.
Assuntos
Infertilidade Masculina/genética , Metiltransferases/genética , Estabilidade de RNA/genética , RNA Interferente Pequeno/genética , Espermatogênese/genética , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/biossíntese , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Cromatina/genética , Elementos de DNA Transponíveis/genética , Regulação da Expressão Gênica no Desenvolvimento , Células Germinativas/crescimento & desenvolvimento , Humanos , Infertilidade Masculina/patologia , Masculino , CamundongosRESUMO
The hypersensitive response (HR) is one of the most efficient forms of plant defense against biotrophic pathogens and results in localized cell death and the formation of necrotic lesions. In this study, a novel putative hypersensitive induced reaction (HIR) gene from wheat leaves infected by incompatible stripe rust pathogen CY23, designated as Ta-hir1, was identified by using rapid amplification of cDNA ends (RACE). Ta-hir1 encodes 284 amino acids, with a predicted molecular mass of 31.31 KDa. A phylogenetic analysis showed that Ta-hir1 was highly homologous to Hv-hir1 from barley at both cDNA and deduced amino-acid levels. Amino-acid sequence analysis of the wheat HIR protein indicated the presence of the SPFH (Stomatins, Prohibitins, Flotillins and HflK/C) protein domain typical for stomatins which served as a negative regulator of univalent cation permeability, especially for potassium. The expression profile of the Ta-hir1 transcript detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time polymerase chain reaction (real time-PCR), respectively, showed that the highest expression occurred 48 h post inoculation (hpi), which is consistent with our previous histopathology observations during the stripe rust fungus-wheat incompatible reaction.
