In Drosophila, absence of Bicoid protein results in larvae missing anterior segments and absence of Nanos protein results in larvae missing posterior segments. Suppose you inject Bicoid protein into the posterior region of early embryos lacking Nanos protein. The expected result would be:

The maternal effect genes are involved in the development of anterior-posterior axis in Drosophila. There are 50 maternal effect genes but only four genes of these are involved in maintaining gradient along the axis. These are Hunchback, Bicoid, Caudal and Nanos.

The Hunchback and Bicoid regulates the development of anterior axis in Drosophila. The Caudal and Nanos regulates the Posterior axis development in Drosophila.

The products of hunchback and bicoid mRNA are required for development of head and thorax. The proteins coded by nanos and caudal are required for abdominal segments. The embryo that lacks nanos do not develop posterior axis. The early embryo injected with Bicoid protein into the posterior region will develop two anterior region.