8500
Since DNA methylation is regulated by DNA methyltransferases and methyl cytosine - binding proteins , this study assessed the extent to which developmental Pb exposure might affect expression of these proteins in the hippocampus .
 Chemical: methyl cytosine; Chemical: Pb
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: methyl cytosine; Chemical: Pb