The function ofbithorax genes in the abdominal central nervous system ofDrosophila.

We have analysed the influence of the bithorax gene complex (BX-C) on two segment-specific features of the central nervous system ofDrosophila larvae: the "presumptive leg neuromeres" (PLN), which are present only in the thoracic ganglia of the larva and develop into the leg neuromeres of the adult fly during metamorphosis; and the "lateral dots" (LD) which are found in the first abdominal as well as thoracic ganglia. We show in both cases that consecutive BX-C genes can suppress the development of these structures. We also show that each gene is expressed in several consecutive segments, leading to an apparent redundancy of the suppression in posterior segments.