In a bowl, combine cornmeal, flour, sugars, baking soda and salt. In another bowl, beat egg, buttermilk and oil; stir into dry ingredients just until moistened. Fill greased or paper-lined muffin cups three-fourths full. Bake at 425° for 12-15 minutes or until muffins test done. Cool in pan for 10 minutes before removing to a wire rack.