Discovery and genetic definition of the Drosophila Antennapedia complex.

0 NE day in 1976 THOM KAUFMAN called me in great excitement. KAUFMAN and I shared an interest in Drosophila homeotic genes located near the third chre mosome centromere. He had recently arrived at Indiana University, and the results of his first set of crosses convinced him that these genes were part of a complex important to anterior developmental commitments (KAuFMAN et aL 1980), just as ED LEWIS’S bithorax complex controlled fate in more posterior regions. He invited me to Bloomington the next summer to join him in a genetic study of this Antennapedia complex (ANTC) . In the late 196Os, KAUFMAN and I had been graduate students together in BURKE JUDD’S lab at the University of Texas. Although my interest in segregation distortion was Ear from the focus of the lab, KAUFMAN worked at its very center: a mutational analysis of the restewhi& region. JUDD was and remains interested in genome organization, and in this pre-molecular era he wished to ascertain all zygotically active functions in this Xchromosome interval necessary for normal morphology and/or viability and to examine the distribution of these loci along the polytene chromosome map (JUDD et al. 1972). In addition to the genetic aspects of this “saturation mutagenesis” effort, KAUFMAN joined MARY SHANNON in a study of the develop mental consequences of the recessive-lethal variants isolated (SHANNON et al. 1972). I left Austin in 1970 for postdoctoral studies with DAN LINDSLEY at UCSD and arrived there at a particularly exciting time. LINDSLEY and long-time collaborator LARRY SANDER were also interested in functional aspects of genetic organization, and I joined their massive effort to systematically generate and study small deficiencies and duplications distributed throughout the genome (LINDSLEY et a,!. 1972). LINDSLEY has served as a repository and chronicler of Drosophila genetic knowledge and takes seriously his responsibility to impart his lore to his students. He pointed out to me an apparent enrichment of homeotic and sex-transforming genes near the third chromosome centromere. These genes were fascinating from a developmental standpoint, and it had been ar-