Fig. 1

Global DNA methylation in placentas. DNA methylation determined by ELISA using a 5-mC-specific antibody (non-smoking group N = 15 and smoking group N = 12). Data represent the means of two experiments. The average DNA methylation percentage for b five consecutive AluYb8 CpG sites (non-smoking group N = 19 and smoking group N = 13) and c three consecutive LINE-1 CpG sites (non-smoking group N = 22 and smoking group N = 17) were determined by pyrosequencing bisulfite-converted DNA. Data represent the means of two runs, except for samples that differed more than 5% in methylation levels within the duplicates. For such samples, a third run was performed and the presented data represent the means of the three runs. Mean methylation percentages ± SD are shown. Unpaired t test was used to compare two groups. A p value < 0.05 was considered statistically significant