RNA-seq facilitates unbiased genome-wide gene-expression profiling. However, its concordance with the well-established microarray platform must be rigorously assessed for confident uses in clinical and regulatory application. Here we use a comprehensive study design to generate Illumina RNA-seq and Affymetrix microarray data from the same set of liver samples of rats under varying degrees of perturbation by 27 chemicals representing multiple modes of action (MOA). The cross-platform concordance in terms of differentially expressed genes (DEGs) or enriched pathways is highly correlated with treatment effect size, gene-expression abundance and the biological complexity of the MOA. RNA-seq outperforms microarray (90% versus 76%) in DEG verification by quantitative PCR and the main gain is its improved accuracy for low expressed genes. Nonetheless, predictive classifiers derived from both platforms performed similarly. Therefore, the endpoint studied and its biological complexity, transcript abundance, and intended application are important factors in transcriptomic research and for decision-making.
In thermodynamics, the one-electron reduction of O 2 by the conduction band electrons of Bi 2 WO 6 or WO 3 is not allowed. However, many studies have reported that Bi 2 WO 6 is photocatalytically active for organic degradation in aerated aqueous suspension. In this work, the photocatalytic activities of Bi 2 WO 6 and WO 3 under visible light have been compared by using phenol degradation as a model reaction. In aerated aqueous solution, Bi 2 WO 6 and WO 3 were indeed active and inactive, respectively, as reported. However, by using Pt as a catalyst for O 2 reduction, or by using H 2 O 2 as an electron scavenger, Bi 2 WO 6 became much less active than WO 3 . Similar results were also obtained in the production of H 2 O 2 under visible light, and in the generation of • OH radicals under UV light, measured by a spin-trapping electron paramagnetic resonance (EPR) spectroscopy. Moreover, in the presence of catalase to completely remove H 2 O 2 , the EPR signal due to • OH radical was reduced, but not disappeared. These observations indicate that the irradiated Bi 2 WO 6 is not only active for water oxidation to • OH but also active for the two-electron reduction of O 2 to H 2 O 2 , the latter of which hardly occurs with the irradiated WO 3 .
Mutations in genes involved in DNA replication such as FEN1, can cause single-stranded DNA breaks (SSBs) and subsequent collapse of DNA replication forks leading to DNA replication stresses. Persistent replication stresses normally induce p53-mediated senescence or apoptosis to prevent tumor progression. It is unclear how some mutant cells can overcome persistent replication stresses and bypass the p53-mediated pathways to develop malignancy. Here we show that formation of polyploidy, which is often observed in human cancers, leads to overexpression of BRCA1, p19arf and other DNA repair genes in FEN1 mutant cells. This overexpression triggers SSB repair and non-homologous end joining pathways to increase DNA repair activity, but at the cost of frequent chromosomal translocations. Meanwhile, DNA methylation silences p53 target genes, to bypass the p53-mediated senescence and apoptosis. These molecular changes rewire DNA damage response and repair gene networks in polyploid tumor cells, enabling them to escape replication stress-induced senescence barriers.
COHCAP (City of Hope CpG Island Analysis Pipeline) is an algorithm to analyze single-nucleotide resolution DNA methylation data produced by either an Illumina methylation array or targeted bisulfite sequencing. The goal of the COHCAP algorithm is to identify CpG islands that show a consistent pattern of methylation among CpG sites. COHCAP is currently the only DNA methylation package that provides integration with gene expression data to identify a subset of CpG islands that are most likely to regulate downstream gene expression, and it can generate lists of differentially methylated CpG islands with ∼50% concordance with gene expression from both cell line data and heterogeneous patient data. For example, this article describes known breast cancer biomarkers (such as estrogen receptor) with a negative correlation between DNA methylation and gene expression. COHCAP also provides visualization for quality control metrics, regions of differential methylation and correlation between methylation and gene expression. This software is freely available at https://sourceforge.net/projects/cohcap/.
The adulteration of herbal products is a threat to consumer safety. Here we surveyed the species composition of commercial Rhodiola products using DNA barcoding as a supervisory method. A Rhodiola dietary supplement DNA barcode database was successfully constructed using 82 voucher samples from 10 Rhodiola species. Based on the DNA barcoding standard operating procedure (SOP), we used this database to identify 100 Rhodiolae Crenulatae Radix et Rhizoma decoction piece samples that were purchased from drug stores and hospitals. The results showed that only 36 decoction piece sequences (40%) were authentic R. crenulata, which is recorded in Chinese Pharmacopeia, whereas the other samples were all adulterants and may indicate a potential safety issue. Among the adulterants, 35 sequences (38.9%) were authenticated as R. serrata, nine sequences (10%) were authenticated as R. rosea, which is documented in the United States Pharmacopeia, and the remaining samples were authenticated as other three Rhodiola species. This result indicates decoction pieces that are available in the market have complex origins and DNA barcoding is a convenient tool for market supervision.
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