In a large bowl, combine both flours, bran, baking soda, baking powder, sugar and salt.
In a separate bowl, mix together egg, oil, and buttermilk.
Make well in the center of flour. Using a fork, gradually mix in liquid ingredients. When the dough leaves the sides of the bowl and can be shaped into a loaf, turn onto a lightly floured surface. Knead lightly for about 5 minutes.
Divide ball in half. Put each half into lightly greased 8 inch round pan. Cut an X across whole top of dough with a sharp knife.
Bake in preheated 400°F oven for 30 minutes until crust is light golden brown, and loaf sounds hollow when rapped with the knuckles. Cool on wire rack.