Cytogenetic analysis of chromosome region 89A of Drosophila melanogaster: isolation of deficiencies and mapping of Po, Aldox-1 and transposon insertions

Summary We have initiated a cytogenetic analysis of chromosome region 89A of Drosophila melanogaster by isolating a set of radiation-induced mutations causing loss of function of P[(w)B]1-1, a transposon bearing the white locus inserted in 89A. Complementation tests and cytological examination of these chromosomes identified four new deficiencies (Df(3R)Po², Df(3R)Po³, Df(3R)Po⁴ and Df(3R)c(3)G²). The new deficiencies and three previously identified deficiencies (Df(3R)sbd²⁶, Df(3R)sbd⁴⁵ and Df(3R)sbd¹⁰⁵) were tested for the ability to complement mutations in the enzyme loci Po and Aldox-1, the indirect flight muscle genes Tm2 and act88F, the morphological mutations jvl, sbd² and Sb, the vital loci srp, pnr and mor, and a newly described vital locus l(3)89Aa. We also used linkage analysis to determine the order and relative positions of P[(w)B]1-1 and an independent transposon insertion, P[w⁺]21, with respect to cv-c, Po, Aldox-1 and sbd². Cytological examination of the deficiencies and analysis of the transformed lines by in situ hybridization permits the correlation of genetically defined regions with specific polytene chromosome bands. A revised cytogenetic map of the 8817–8913 region is presented.