Figure 1.

Cytogenetic and molecular characteristics of the approximately 2-megabase region at the base of the X chromosome of Drosophila melanogaster. Polytene subdivisions 19A through 19F and 20A through 20F are as shown. The 67-kb flightless region (in blue) is expanded to illustrate the 12 primary transcription units. The genomic transforming fragments used to rescue the mutant phenotypes are T1 through T8. The deficiencies used to uncover the mutant phenotypes are designated D1 through D8 (dotted lines represent the deficiency, and the approximate breakpoints are shown in orange). Deficiencies D1 through D8 correspond to deficiencies 17–257, GA104, GE263, 2/19B, JC77, 16–129, HM44, and Q539 (1–8).