Genetics, Vol. 182, 631-639, July 2009, Copyright © 2009
doi:10.1534/genetics.109.104083

The Complex Tale of the achaete–scute Complex: A Paradigmatic Case in the Analysis of Gene Organization and Function During Development

Antonio García-Bellido1,2 and Jose F. de Celis1

Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientffícas and Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain

2 Corresponding Author: Antonio García-Bellido, Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain. Email: agbellido{at}cbm.uam.es

The achaete–scute gene complex (AS-C) contains four genes encoding transcription factors of the bHLH family, achaete, scute, lethal of scute, and asense located in 40 kb of DNA containing multiple cis-regulatory position-specific enhancers. These genes play a key role in the commitment of epidermal cells toward a neural fate, promoting the formation of both sensory organs in the peripheral nervous system (bristles) of the adult and of neuroblasts in the central nervous system of the embryo. The analysis of the AS-C initially focused on the variations in positional specificity of effects of achaete (ac) and scute (sc) alleles on macrochaete bristle pattern in the Drosophila adult epidermis, and from there it evolved as a key entry point into understanding the molecular bases of pattern formation and cell commitment. In this perspective, we describe how the study of the AS-C has contributed to the understanding of eukaryotic gene organization and the dissection of the developmental mechanisms underlying pattern formation.