Fig. 4
Competitive hybridization using custom-glass array for comparison of −499-CpG methylation level between control and TCDD-treated mouse liver DNAs. a Glass array image of the merged Cy3 and Cy5 fluorescence. Three spots of Rat E-cadherin oligo and Mouse Cyp1a1 oligo were set on one block. Using the new method in this study, Cy3- and Cy5-labeled aRNAs were produced using control and TCDD-treated mouse liver DNAs, respectively. They were then competitively hybridized on the custom glass array. The picture represents three independent blocks. Image and each spot fluorescence was obtained by GenePix instrument. Note that the spots of Rat E-cadherin oligo spot showed yellow whereas the spots of Mouse Cyp1a1 oligo showed green, indicating −499-CpG methylation level of control mouse is higher than that of TCDD-treated mouse. b Comparison of fluorescence intensity between control (Cy3) and TCDD-treated mice (Cy5). Averages of relative spot fluorescence intensity of Mouse Cyp1a1 oligo of each dye were calculated as described in Materials and Methods. Relative fluorescence intensity representing −499-CpG methylation level was calculated to divide the mean of Mouse Cyp1a1 oligo spot intensity (arrowed 3 spots, in A) by the mean of Rat-E-cadherin spot intensity (arrowed 3 spots, in A) of each dye. Three data (Block1 to 3) were used in the statistical analysis (Student’s t-test)