Dissection of chromosome region 89A of Drosophila melanogaster by local transposition of P elements.

In the chromosome region 89A of Drosophila melanogaster, a few meiotic genes have been suggested to exist besides c3G and rec. We carried out local mutagenesis using a strain carrying a P element-insertion (plwB) at 89A, and obtained new genetic variants. Two are female sterile mutations, an allele of the homeless locus (hls167) and a new mutation tibi (tbi), and three are lethal mutations at the serpent locus. The tbi mutation is a paternally-rescuable maternal-effect-lethal. Destabilization of the P elements revealed that these mutations were caused by P element-insertions, and produced 12 deletion lines. These lines were then used for systematic complementation test. The results showed that: (1) hls, tbi and at least three lethal genes in addition to c3G, rec and l(3)89Aa are located within the deletion of Df(3R)c3G2(89A2-3; 89A4-5); (2) the gene order is rec, tbi, hls (from centromere to telomere), and both c3G and l(3)89Aa are possibly located proximally. We cloned 117 kb of DNA from this region by plasmid rescue and chromosome walking, and mapped several of the breakpoints of the deletions. These analyses delimited the rec gene to within 21 kb of the cloned DNA, although the c3G gene could not be located on the molecular map.