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Objective: To investigate the possible role of miR-449a/b in the occurrence of gastric cancer., Methods: The expression of miR-449a/b and E2F1 mRNA in gastric cancer cells BGC-823 and gastric mucosal cells GES-1 were detected with qRT-PCR. miR-449a/b mimics or a negative control was transiently transfected into BGC-823 cells, and the changes in cell proliferation, apoptosis, and migration ability were assessed using CCK-8 assay, flow cytometry, and scratch wound healing assay, respectively. Western blotting was used to observe the effects of miR-449a/b upregulation on its target gene expression. The effects of transfection with an E2F1-over-expressing plasmid or an empty plasmid were analyzed on the expression level of miR-449a/b in BGC-823 cells using qRT-PCR and digital PCR., Results: The gastric cancer cell line BGC-823 showed significantly a lowered expression of miR-449a/b compared with the normal gastric mucosal cell line GES-1 ( P < 0.01). Overexpression of miR-449a/b obviously inhibited the proliferation and migration and promoted apoptosis of BGC-823 cells ( P < 0.05). Overexpression E2F1 in the cells resulted in significantly up-regulated expression of miR-449a/b ( P < 0.001). Upregulation of miR-449a/b caused significant down-regulation of its direct target genes CDK4 and CDK6 and also of the expression of E2F1 protein via the CDKs-pRb-E2F1 signaling pathway., Conclusions: The low expression of miR-449a/b and the high expression of E2F1 are both involved in the occurrence and progression of gastric cancer, and miR-449a/b negatively regulates E2F1 to inhibit the proliferation of gastric cancer cells.

Objective: To study the effects of cigarette smoke on the oxidative damage of mice oocytes and developmental potential., Methods: A total of 96 SPF grade 6-week-old ICR female mice were randomly divided into control group, low-dose group, middle-dose group and high-dose group according to the principle of similar body weight. Twenty-four mice in each group were placed in a cigarette-lighting containers with the volume of 60, 32 and 23 L respectively. The control group was fed normally twice a day for 1 hour for 4 weeks. Weight and record daily, draw weight change curve; use kit to detect the activity of superoxide dismutase(SOD) and glutathione peroxidase(GPX) in ovarian tissue; use tissue section, indirect immunofluorescence and in vitro maturation technology to detect the activity of each group. The ovarian organ index, the level of reactive oxygen species(ROS) in oocyte and the first polar body rate were measured. The t test was used to compare the mean values of the two groups, and one-way ANOVA was used to compare the mean values of the multiple groups., Results: Compared with the control group, the weight gain of mice in the treatment group was significantly slower(the weight gain in the high dose group was only 1. 05%±0. 41%). The ovarian organ index, SOD and GPX activity in the ovarian tissue and litter size(the high dose group was reduced to 5. 20%±1. 48%) were significantly decreased. The ROS level in oocyte was significantly increased, and oocyte maturation in vitro was the first. The polar body rate decreased(high dose group decreased to 49. 34%±5. 78%), and the difference was statistically significant(P<0. 05)., Conclusion: Cigarette smoke exposure in mice can cause the decrease of ovarian organ index, SOD and GPX activity, the increase of ROS content in oocyte, the decrease of first polar body rate and litter size.

Objective: To study the effect of cigarette smoke on chromatin configuration, DNA methylation and expression of related genes in mice oocytes., Methods: The clean grade ICR female mice were divided into 3 groups, control group, low dose group and high dose group. Animals were placed inside a perspex chamber( 18L) filled up with the smoke produced by 0, 1, 2 cigarettes, one hour a time, twice daily for 4weeks. Nuclear staining with Hoechst 33342, to observe the quality of oocyte and chromatin configuration. Analysis of the DNA methylation patterns by indirect immunofluorescence. The expressions of DNA methyltransferases( DNMT) 1, DNMT3a and DNMT3b mRNA were detected by quantitative real time PCR., Results: With the increase of smoke concentration, the diameter of oocytes was significantly decreased( P <0. 05), the percentage of non surrounded nucleolus( NSN) chromatin configuration was significantly increased( P < 0. 05). In high dose group, the level of DNA methylation wassignificantly lower than that of control group( P < 0. 05). The expression of DNMT1 decreased with the increase of smoke concentration, but the expression level of DNMT3b was significantly decreased( P < 0. 05)., Conclusion: Cigarette smoke exposure may alter oocyte chromatin configuration, decrease the expression level of DNMTs, resulted in oocytes DNA methylation decreased, so as to decrease the quality of oocytes.

Objective: To predict B cell epitopes of hemagglutinin (HA) of human-infecting H6N1 avian influenza virus and analyze their evolutionary characteristics., Methods: The dataset was downloaded from GISAID and GenBank databases. And the linear and conformational B cell epitopes of HA were predicted separately by various bioinformatic software. Furthermore, the conservation, adaptation and other evolutionary characteristics were also analyzed by some bioinformatic means., Results: Four linear epitopes (A, B, C and D) and two conformational epitopes (E and F) were obtained after consideration of multiple factors. And the C epitope and sites ( 41, 157, 186, 187) mutated easily, but the other epitopes were very conservative and the D epitope was the most conservative. Interestingly, the site 157 was identified under positive selection, suggesting that it may be a particularly important site to make the virus evade the attack from the host immune system., Conclusion: The HA of human-infecting H6N1 avian influenza virus has five conservative B cell epitopes (three linear and two conformational) and one site under positive selection. The findings would facilitate the vaccine development, virus control and pathogenesis understanding.