In a large bowl, combine 1 cup all-purpose flour, 1 cup whole wheat flour, sugar, undissolved yeast, and salt.
Heat water, milk, and butter until very warm (120*F to 130*F). Gradually add to flour mixture. Beat 2 minutes at medium speed of electric mixer, scraping bowl occasionally. Add egg, vanilla, and 1 cup all-purpose flour; beat 2 minutes at high speed. Stir in remaining all-purpose flour to make a stiff batter.
Dredge blueberries in remaining 1/4 cup whole wheat flour; gently fold into muffin batter.
Fill 18 greased (2-inch) muffin cups 3/4 full. Cover; let rise in warm, draft-free place until doubled in size, about 1 hour.