In Drosophila, a gradient of Bicoid protein (BCD) originates from prelocalized mRNA at the anterior pole of the egg and establishes developmental programs including those for the larval head and thorax in a concentration-dependent manner [1,2]. Orthologous proteins have been reported only from cyclorrhaphan flies [3,4]. However, a BCD-like determinant has been postulated for a large variety of ...
