Deficiency mapping of quantitative trait loci affecting longevity in Drosophila melanogaster

In a previous study, sex-specific quantitative trait loci (QTL) affecting a dult longevity were mapped by linkage to polymorphic roo transposable eleme nt markers, in a population of recombinant inbred lines derived from the Or egon and 2b strains of Drosophila melanogaster. Two life span QTL were each located on chromosomes 2 and 3, within sections 33E-46C and 65D-85F on the cytological map, respectively. We used quantitative deficiency complementa tion mapping to further resolve the locations of life span QTL within these regions. The Oregon and 2b strains were each crossed to 47 deficiencies sp anning cytological regions 32F-44E and 64C-76B, and quantitative failure of the QTL alleles to complement the deficiencies was assessed. We initially detected a minimum of five and four QTL in the chromosome 2 and 3 regions, respectively, illustrating that multiple linked factors contribute to each QTL detected by recombination mapping. The QTL locations inferred from defi ciency mapping did not generally correspond to those of candidate genes aff ecting oxidative and thermal stress or glucose metabolism. The chromosome 2 QTL in the 35B-E region was further resolved to a minimum of three tightly linked QTL, containing six genetically defined loci, 24 genes, and predict ed genes that are positional candidates corresponding to life span QTL. Thi s region was also associated with quantitative variation in life span in a sample of 10 genotypes collected from nature. Quantitative deficiency compl ementation is an efficient method for fine-scale QTL mapping in Drosophila and can be further improved by controlling the background genotype of the s trains to be tested.