Bisphenol A Exposure Disrupts Genomic Imprinting in the Mouse
Figure 5
Analysis in control and upper dose BPA exposed placentas indicated that exposure significantly reduced methylation.
The Snrpn ICR is depicted in (A), including the sequences analyzed in the (B) pyrosequencing and (C) bisulfite sequencing assays. A. 16 CpG sites (highlighted in red and bold) located in a 451 bp region of the Snrpn ICR were assayed by bisulfite sequencing. The underlined genomic sequence containing 7 CpGs represents the region analyzed by pyrosequencing. B. Pyrosequencing data in control, lower dose and upper dose BPA exposure are shown with samples exhibiting monoallelic (black circles) or biallelic expression of Snrpn (red circles). Y-axis represents percentage of total methylation. Black horizontal line in each exposure group indicates average methylation. Sample sizes analyzed in each exposure group are shown; a = P<0.05 when analyzed through ANOVA but not significant through Kruskal-Wallis. C. Three placentas from both control and upper dose BPA exposure groups were analyzed by bisulfite sequencing and shown here is the methylation status of maternal ICR. Each circle represents a CpG site with black = methylated and white = unmethylated. Percentages of methylation at all CpGs are indicated. Average CpG methylation levels are 82.0±4.3% in controls and 53.8±2.4% in upper dose (P<0.01).