Comparison of methylation level of genomes among different animal species and various tissues.

The methylation levels of genomes were compared in swine, cattle, sheep, rat, chicken and duck, using the methylation-sensitive amplification polymorphism technique (MSAP). The results showed that the methylation levels in genomes of the species investigated were mostly about 40–50% (except cattle); the methylation level varied in different species; the methylation pattern in various tissues of each species was specific; for the same species, the methylation level of the tissue genome was mostly higher than that of the blood genome; the difference of methylation level between birds and mammals was not significant, however mammals appeared to have a lower hemi-methylation frequency and higher full methylation frequency than birds. [ABSTRACT FROM AUTHOR]