[Natural Water Chemistry Change in the Surface Water of Chengdu and Impact Factors].

To investigate the impact of megacities on the chemistry of surface waters, monthly sampling and monitoring were conducted in the Chengdu section of the Minjiang and Tuojiang River basin, corresponding to the upper reaches of the Yangtze River since the spring of 2019, including the influent and effluent water samples from 57 sewage treatment plants in Chengdu. All the samples were analyzed for major ions and other water chemistry parameters, and compared with the historical data of the Minjiang and Tuojiang River. The results showed that the Chengdu surface water still presented a natural chemistry with medium-low total dissolved solids(TDS), and calcium bicarbonate chemistry type, which is the natural consequence of the weathering of carbonate rocks in the basin effected by the weathering of silicates and evaporites.

[Changes in Water Chemistry and Driving Factors in the Middle and Lower Reaches of the Beijing-Hangzhou Grand Canal].

To reveal the Beijing-Hangzhou Grand Canal natural water chemistry characteristics and the influence of human activities, river samples from Xuzhou to Jiaxing were collected in 2019-2020. Simultaneously, the water chemistry data of the canal from 1959 to 1962 and 1975 to 1977 in the Suzhou, Wuxi, and Changzhou sections and the recent social and economic data of the major cities along the canal were collected and analyzed. The results showed that the type of hydrochemistry in the study area was mainly influenced by the weathering of carbonate rocks in the basin, but K+Na accounted for 40.

Regulation of hMSH2 and hMLH1 expression in the human colon cancer cell line SW1116 by DNA methyltransferase 1.

Aberrant DNA methylation is now recognized as an important epigenetic alteration occurring early in human cancer. To directly study the role of DNA methyltransferase 1 (DNMT1) in the regulation of expression of tumor-related genes in human colon cancer cells, we stably transfected expression constructs containing sense or antisense DNMT1 into the human colon cancer cell line, SW1116. The expression level of mismatch repair genes (MMR), human mut-L homologue 1 (hMLH1) and human Mut S homologue 2 (hMSH2), was monitored by real-time RT-PCR.

Expression of Dnmt1, demethylase, MeCP2 and methylation of tumor-related genes in human gastric cancer.

Aim: To explore the effect of DNA methyltransferase, demethylase and methyl-CpG binding protein MeCP2 on the expressions and methylation of hMSH2 and proto-oncogene in human gastric cancer.

Methods: Paired samples of primary gastric cancer and corresponding para-cancerous, non-cancerous gastric mucosae were obtained from surgically resected specimens of 28 patients. Transcription levels of Dnmt1, mbd2, MeCP2, p16(INK4A), hMSH2 and c-myc were detected by using real-time PCR or RT-PCR.

[Effect of eukaryotic expression plasmid DNA methyltransferase gene on methylation status and transcription level of DNA mismatch repair genes in human colon cancer cell line].

Objective: To analyze the effect of eukaryotic plasmids containing sense or antisense DNA methyltransferase (Dnmt1) genes on the methylation status and transcription level of DNA mismatch repair (MMR) genes and microsatellite instability (MSI) in human colon cancer cell line.

Methods: Human colorectal cells of the SW1116 line were cultured. Recombinant plasmids containing sense Dnmt1 (HMT) or antisense Dnmt1 (THM) gene, pCMV-HMT and pCMV-THM, were constructed.

Histone acetylation regulates p21WAF1 expression in human colon cancer cell lines.

Aim: To investigate the effect of histone acetylation on regulation of p21WAF1 gene expression in human colon cancer cell lines.

Methods: Two cell lines, Colo-320 and SW1116 were treated with either trichostatin or sodium butyrate. Expressions of p21WAF1 mRNA and protein were detected by real-time RT-PCR and Western blotting, respectively.

5-Aza-2'-deoxycitydine induces demethylation and up-regulates transcription of p16INK4A gene in human gastric cancer cell lines.

Background: To investigate the effects of DNA methylation on the expression of tumor-associated genes and the cell cycle in human gastric cancer cells.

Methods: Two gastric cancer cell lines (MKN-45 and HGC-27) were treated with DNA methyltransferase (DNMT) inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC). The expressions of p16INK4A, p21WAF1, p53, p73, c-Ha-ras and c-myc genes mRNA were detected by using reverse transcription PCR (RT-PCR).