CHROMOSOMAL LOCALIZATION AND REGULATION OF THE LONGEVITY DETERMINANT GENES IN A SELECTED STRAIN OF DROSOPHILA-MELANOGASTER

A controlled chromosome substitution experiment was performed on a strain (NDC-L) selected for long life to determine if the genes responsible for the extended-longevity phenotype could be localized to any particular chromosome(s). All 27 different possible combinations of the three major chromosomes of Drosophila melanogaster were constructed and longevities were determined on 3875 individual animals of both sexes and analysed. The results are statistically significant and demonstrate that mean longevity is specified primarily by recessive genes on the third chromosome (c3). The extended longevity phenotype (ELP) is only expressed in those lines which are homozygous for the NDC-L type c3. Loci on the first (c1) and second (c2) chromosomes interact, both positively (cl) and negatively (c2), respectively, such that c1 represses c2 which in turn represses c3. The ELP is fully expressed in the mutual presence and mutual absence of cl and c2. The significance of these results is discussed in the context of broader categories of molecular genetic mechanisms suggested previously to be involved in the modulation of longevity in Drosophila.