Chromosomal localization and regulation of the longevity determinant genes in a selected strain of Drosophila melanogaster

Abstract

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 (ci) and second (c2) chromosomes interact, both positively (ci) and negatively (c2), respectively, such that ci represses c2 which in turn represses c3. The ELP is fully expressed in the mutual presence and mutual absence of ci 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.

Larval regulation of adult longevity in a genetically-selected long-lived strain of Drosophila

“…We had constructed 27 different isogenic lines, each of which had a unique combination of R-and L-type ci, c2, and/or c3 chromosomes. The construction and longevity characteristics of these isogenic lines have been described (Buck et a!., 1993). Replicates of a number of these isogenic lines in which the females were known to express the extended-longevity phenotype (222,202,002), as well as replicates of a number of lines known to express only a shorter than normal life span (010, 011, 020, 100, 110),aR-type life span (000,001,012,022,112,200,211) or an intermediate-type life span (101,102,111,201,220) were each raised under low larval density (LD) conditions.…”

“…Stock construction, measurement of life span, culture conditions, use of the paraquat test to test the presence or absence of the extended-longevity phenotype, and data analysis were carried out as described by Buck et al (1993) and Arking et a!. (1991).…”

“…¶Correspondence. and second (c2) chromosomes, such that c3 was repressed by c2 which was in turn repressed by ci, thus allowing the expression of the longevity-determinant genes on c3 (Buck et aL, 1993). That analysis allowed us to identify and characterize both the additive and non-additive genetic effects.…”

“…We determined that the recessive genes necessary and sufficient for the expression of the extended-longevity phenotype in our genetically-selected NDC-LA (L or 222, using the terminology described by Buck et aL 1993) strain of Drosophila melanogaster are on the third chromosome (c3). We also showed that the expression of the extended-longevity phenotype by these c3 genes was dependent on the composition of the animal's first (ci) *This paper is dedicated to the memory of Howard A. Schneiderman, an enthusiastic scholar, a creative administrator and a good human being.…”

“…Introduction Buck et al (1993) examined a number of isogenic lines to determine which chromosome(s) were responsible for the expression of the extended-longevity phenotype when the animals were reared under high larval density (HD, > 50 larvae/vial) conditions. We determined that the recessive genes necessary and sufficient for the expression of the extended-longevity phenotype in our genetically-selected NDC-LA (L or 222, using the terminology described by Buck et aL 1993) strain of Drosophila melanogaster are on the third chromosome (c3).…”