Differences of genome-wide methylation level and methylated genes be-tween nasopharyngeal carcinoma cells in same genetic background but different radiation resistance / 中国病理生理杂志

[ ABSTRACT] AIM:To compare the differences of the genome-wide methylation levels and methylated regions be-tween nasopharyngeal carcinoma ( NPC) cells in the same genetic background but different radiation resistance ( CNE-2 cells and CNE-2R cells).METHODS:Using the method which was developed by Doctor Zhao Cun-you, based on using methyl-sensitive restriction enzyme to measure the genome-wide methylation levels.In addition, MeDIP-Seq was used to analyze the methylated regions in 6 gene functional elements, including the upstream 2k sequence, 5’ UTR, coding se-quence, intron, 3’UTR and downstream 2k sequence, between CNE-2 cells and CNE-2R cells.RESULTS:The genome-wide methylation level was approximately 30%lower in CNE-2R cells than that in CNE-2 cells.No obvious difference on the amount of genes and the coverage of the peak in the 6 gene functional elements was observed.However, the methylation pattern of plentiful genes had altered in the gene function elements.CONCLUSION:The genome-wide methylation levels and methylated regions between NPC cells in the same genetic background but different radiation resistance were quite dif-ferent, indicating that the DNA methylation may be associated with NPC radioresistance.

Sewage treatment plant serves as a hot-spot reservoir of integrons and gene cassettes.

This study investigated the occurrence and abundance of class 1 integrons and related antibiotic resistance genes (ARGs) in a sewage treatment plant (STP) of China. Totally, 189 bacterial strains were isolated from influent, activated sludge and effluent, and 40 isolates contained the integons with a complete structure. The intI1-carrying isolates were found to harbor two types of gene cassettes: dfr17-aadA5 and aadA2, conferring resistances to trimethoprim and streptomycin, which were further confirmed by antimicrobial susceptibility analysis. Many other gene cassettes were carried on integron, including qnrVC1, catB-8-blaoxa-10-aadA1-aac(6'), aadB-aacA29b, aadA2, aac(6')-1b, aadA6 and aadA12, which were detected using DNA cloning. Quantitative real time PCR showed that over 99% of the integrons was eliminated in activated sludge process, but average copy number of integrons in given bacterial cells was increased by 56% in treated sewage. Besides integrons, other mobile gene elements (MGEs) were present in the STP with high abundance. MGEs and the associated ARGs may be wide-spread in STPs, which constitute a potential hot spot for selection of antibiotic resistant bacteria and horizontal transfer of ARGs.