Figure 4

Methylation dynamics of short interspersed repeats. Short Interspersed Nuclear Elements (SINE) were investigated for their methylation level in the porcine germ line. A DNA pool from germ cells of 13-16 embryos of the stages E22, E25, E29-31 and E42 was bisulphite converted and used for the analysis after one PCR reaction and subsequent transformation and cloning. 11-24 clones were analysed from each group. Due to high mutagenic rate in this type of elements, single clones are not identical regarding number and position of CpGs. The mean methylation level was calculated as suggested by Yang et al. [52] and results shown in the diagram. The sequence of an example of the investigated fragments after bisulfite mutagenesis is shown. Bars on the columns indicate SEM. E: embryonic stage.