DNA methylation in folate deficiency: use of CpG methylase.

Folate deficiency produces a marked decrease in the ratio of S-adenosylmethionine to S-adenosylhomocysteine. This ratio regulates the activity of many cellular methylation reactions including that of DNA. We used bacterial CpG methylase to evaluate the effect of folate deficiency on methylation of DNA from livers of weanling rats fed an amino acid-defined folate deficient diet. After 4 weeks, liver DNA from deficient animals was undermethylated compared with DNA from pair-fed control animals.